JP2004339070A - Thiophene derivatives, method for producing the same and organic electroluminescent element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a compound having not only excellent hole block ability as an organic electroluminescent element and sufficient emission luminance even under driving at a low voltage but also excellent film-forming properties in a vapor-deposited film for forming an electron transport layer or a luminescent layer and to provide the organic electroluminescent element using the compound as an electron transport material or a luminescent material. <P>SOLUTION: 3,4-Diphenylthiophene is reacted with n-butyllithium and the resultant reaction product is then reacted with trimethoxyborane. The obtained compound is subsequently subjected to a coupling reaction with 2,6-dichloropyrazine in the presence of a base and a palladium catalyst to provide 2,6-bis(3,4-diphenylthiophen-2-yl)pyrazine. The resultant 2,6-bis(3,4-diphenylthiophen-2-yl)pyrazine is used as the electron transport material or luminescent material in the organic electroluminescent element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

〔式中、Ｒ^１及びＲ^２は互いに同じか或いは異なってそれぞれ水素原子、アルキル基又はアルコキシ基を表し、Ｒ^３は水素原子、アルキル基、アラルキル基、アリール基または複素環基を示し、−Ａｒ−は下式（２）

（式中、Ｒ^４はアルキル基を示し、ｍは０〜３の整数である。）
または下式（３）

（式中、Ｒ^５はアルキル基を示し、ｎは０〜２の整数である。）
または下式（４）

（式中、Ｒ^６はアルキル基を示し、ｐは０〜２の整数である。）
または下式（５）

（式中、Ｒ^７はアルキル基を示し、ｑは０〜２の整数である。）
または下式（６）

（式中、Ｒ^８はアルキル基を表し、ｒは０〜２の整数である。）
のいずれかを示す。〕
で示されるチオフェン誘導体類を提供するものである。
【００１２】
また、本発明の第２は、下記一般式（７）

（式中、Ｒ^１、Ｒ^２およびＲ^３は前記と同じである。）
で示されるアリールチオフェン類をアルキルリチウムと反応させた後、得られた反応混合物に下記一般式（８）
Ｂ（ＯＲ^９）_３
（式中、Ｒ^９はアルキル基を表す。）
で示されるトリアルコキシボラン類を加えて反応させて下記一般式（９）

（式中、Ｒ^１、Ｒ^２、Ｒ^３およびＲ^９は前記と同じである。）
で示されるジアルコキシチエニルボラン類を得、次いで下記一般式（１０）
Ｘ−Ａｒ−Ｘ
〔式中、Ｘはハロゲン原子を表し、−Ａｒ−は前記式（２）〜式（６）と同じである。〕
で示されるジハロゲン置換アリール化合物もしくは複素環式化合物と、溶媒中、パラジウム触媒及び塩基の存在下に反応させることを特徴とする前記一般式（１）示されるチオフェン誘導体類の製造法を提供するものである。
【００１３】
更に、本発明の第３は、前記一般式（１）で示されるチオフェン誘導体類を含む有機層を有してなる有機電界発光素子を提供するものである。
【００１４】
【発明の実施の形態】
前記一般式（１）で示されるチオフェン誘導体類において、置換基Ｒ^１およびＲ^２は互いに同じか或いは異なってそれぞれ水素原子、アルキル基またはアルコキシ基であり、アルキル基としてはメチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基などの直鎖状又は分枝鎖状の好ましくは炭素数１〜４の低級アルキル基が、アルコキシ基としてはメトキシ基、エトキシ基、ｎ−プロポキシ基、ｎ−ブトキシ基などが挙げられるが、特に好ましくは水素原子である。
【００１５】
置換基Ｒ^３は水素原子、アルキル基、アラルキル基、アリール基または複素環基であり、ここでアルキル基としては前記と同様のアルキル基が例示され、アラルキル基とはこれらアルキル基が有する水素原子をアリール基に置換した基であって、具体的にはベンジル基、メチルベンジル基、フェネチル基、ナフチルメチル基、ジフェニルメチル基などが例示され、アリール基としては置換基を有していてもよい芳香族炭化水素基、たとえばフェニル基、トリル基、キシリル基、ナフチル基、メチルナフチル基などが例示され、複素環基としてはピリジル基、キノリル基、イソキノリル基などが例示される。
【００１６】
また、前記式（２）、（３）、（４）、（５）および（６）で示される置換基−Ａｒ−において、各式中のＲ^４，Ｒ^５，Ｒ^６、Ｒ^７およびＲ^８で示されるアルキル基は前記と同様である。
【００１７】
本発明のチオフェン誘導体類（１）としては、前記一般式（１）において置換基Ｒ^１およびＲ^２の全てが水素原子であって置換基Ｒ^３が水素原子または複素環基であり、かつ、置換基−Ａｒ−が前記式（２）〜（５）で示され、その置換基Ｒ^４，Ｒ^５，Ｒ^６またはＲ^７の数を示すｍ、ｎ、ｐおよびｑが０であるか、置換基−Ａｒ−が前記式（６）で示されるチオフェン誘導体類が好ましい。
【００１８】
このようなチオフェン誘導体類（１）としては、例えば２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジン、２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジン、４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジン、３，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリダジン、１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼン、１，４−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼン、２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−（２−キノリル）チオフェン−５−イル］ベンゼン等を具体的に挙げることができるが、これらの例示化合物に限定されるものではない。
【００１９】
このような一般式（１）で示される本発明のチオフェン誘導体類は、例えば、前記一般式（４）で示されるアリールチオフェン類をアルキルリチウムと反応させた後、前記一般式（５）で示されるトリアルコキシボランと反応させ、次いでパラジウム触媒の存在下に一般式（７）で示されるハロゲン置換アリール化合物もしくは複素環式化合物と反応させることにより製造することができる。
【００２０】
以下、この製造方法について詳細に説明する。
反応原料である一般式（４）で示されるアリールチオフェン類としては、目的とするチオフェン誘導体類に対応する化合物が選択使用され、例えば３，４−ジフェニルチオフェン、３，４−ジフェニル−２−｛２−ピリジル｝チオフェン等を挙げることができるがこれらに限定されない。
【００２１】
また、アルキルリチウムとしては、エチルリチウム、ｎ−プロピルリチウム、ｎ−ブチルリチウムなどが例示されるが、ｎ−ブチルリチウムが取扱い性や反応性の点で好ましく使用される。
【００２２】
一般式（４）で示されるアリールチオフェン類とアルキルリチウムとの反応は、通常、有機溶媒中で行われる。
有機溶媒としては、反応に不活性なものであれば特に限定されず、例えば、ジメトキシエタン、ジエチルエーテル、テトラヒドロフラン等のエーテル類、ヘキサン、ヘプタン、オクタン等の脂肪族炭化水素等が挙げられるが、反応にはこれらの１種以上を使用することができる。
【００２３】
この反応において、アルキルリチウムの使用量は一般式（４）で示されるアリールチオフェン類に対して通常０．８〜２モル倍、好ましくは１〜１．５モル倍の範囲である。
有機溶媒の使用量は特に限定はないが、一般的には一般式（４）で示されるアリールチオフェン類に対して１〜１００重量倍である。
反応温度は、通常、室温以下、好ましくは−８０℃〜０℃である。
【００２４】
かかる反応により、一般式（４）で示されるアリールチオフェン類のチオフェン核の５−位がリチウムで置換された下記式（１１）で示されるアリールチエノリチウム類が得られる。

（式中、Ｒ^１、Ｒ^２およびＲ^３は前記と同じである。）
【００２５】
尚、この反応においては、アルキルリチウムおよび生成したアリールチエノリチウム類が水と容易に反応して分解するところから、反応系を実質的に無水の状態に保つことが好ましい。
【００２６】
次いで、かくして得られたアリールチエノリチウム類を前記一般式（８）で示されるトリアルコキシボラン類と反応させて、前記一般式（９）で示されるジアルコキシチエノボラン類を製造する。
反応方法としては前記反応混合物からアリールチエノリチウム類を単離したのち、上記したと同様の有機溶媒中でトリアルコキシボラン類と反応させてもよいが、通常は、アリールチエノリチウム類を含む反応混合物にトリアルコキシボラン類を加えて、アリールチエノリチウム類とトリアルコキシボラン類を反応させることにより行われる。
【００２７】
ここで、前記一般式（８）で示されるトリアルコキシボラン類において、置換基Ｒ^９のアルキル基としてはメチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、ｔ−ブチル基などの直鎖状又は分枝鎖状の好ましくは炭素数１〜３の低級アルキル基が挙げられ、トリアルコキシボラン類の具体例としてはトリメトキシボラン、トリエトキシボラン、トリ−ｎ−プロポキシボランなどが挙げられる。
【００２８】
この反応におけるトリアルコキシボラン類の使用量は、出発原料であるチオフェン類１モルに対して通常１〜３．５モルの範囲であり、反応温度は先の反応の場合と同様に、通常、室温以下、好ましくは−８０℃〜０℃である。
【００２９】
反応終了後、生成したジアルコキシチエノボラン類を含む反応混合物にアルコール類例えばメタノール、エタノールなどを加えたのち、減圧留去法などにより溶媒類を除去する。
【００３０】
溶媒留去後の残渣に、ジメチルホルムアミドなどの溶媒を加えてこれを溶解し、このジアルコキシチエノボラン類溶液に前記一般式（１０）で示されるジハロゲン置換アリール化合物もしくは複素環式化合物を加えてパラジウム触媒および塩基の存在下にカップリング反応を行い、目的とする一般式（１）で示されるチオフェン誘導体類を得る。
【００３１】
ここで、一般式（１０）で示されるジハロゲン置換アリール化合物もしくは複素環式化合物としては、ｐ−ジブロモベンゼン、ｍ−ジブロモベンゼン、２，６−ジクロロピリジン、２，６−ジブロモピリジン、２，６−ジクロロピペリジン、２，６−ジクロロピラジン、４，５−ジクロロピリミジン、４，６−ジクロロピリミジン、３，６−ジクロロピリダジン、１，４−ジブロモ−２，５−ジメトキシベンゼンなどが例示され、その使用量は出発原料であるアリールチオフェン類に対して０．１〜１モル倍である。
【００３２】
パラジウム触媒としては、テトラキス（トリフェニルホスフィン）パラジウム、ジクロロビス（トリフェニルホスフィン）パラジウム、ジクロロビス（トリフェニルホスフィン）パラジウム、ジクロロ［ビス（ジフェニルホスフィノ）エタン］パラジウム、ジクロロ［ビス（ジフェニルホスフィノ）ブタン］パラジウム、ジクロロ［ビス（ジフェニルホスフィノ）フェロセン］パラジウム等のパラジウム錯体を挙げることができるが、ジクロロ［ビス（ジフェニルホスフィノ）フェロセン］パラジウムが好ましく使用される。
【００３３】
かかるパラジウム触媒の使用量は、触媒に含まれる金属パラジウムが一般式（１０）で示されるジハロゲン置換アリール化合物もしくは複素環式化合物１モルに対して通常０．００５〜０．５モル、好ましくは０．０１〜０．１５モル倍である。
【００３４】
塩基としては、公知の無機塩基を広く使用でき、例えば、アルカリ金属炭酸塩、アルカリ金属炭酸水素塩、アルカリ金属水酸化物、アルカリ金属リン酸塩、アルカリ金属フッ化物、及びアルカリ土類金属の塩基性塩が挙げられ、これらは１種単独で又は２種以上混合して使用できる。
【００３５】
具体的には、アルカリ金属炭酸塩としては炭酸ナトリウム、炭酸リチウム、炭酸セシウムなどが、アルカリ金属炭酸水素塩としては炭酸水素ナトリウム、炭酸水素カリウム等が、アルカリ金属水酸化物としては水酸化ナトリウム、水酸化カリウム、水酸化リチウム、水酸化セシウムなどが、アルカリ金属リン酸塩としてはリン酸ナトリウム、リン酸カリウム、リン酸リチウム、リン酸セシウムなどが、アルカリ金属フッ化物としては、具体的にはフッ化ナトリウム、フッ化カリウム、フッ化セシウム等が例示される。
【００３６】
また、アルカリ土類金属の塩基性塩としては、例えばアルカリ土類金属の炭酸塩、炭酸水素塩、水酸化物等が挙げられ、これらの具体例としては炭酸マグネシウム、炭酸カルシウム、炭酸水素マグネシウム、炭酸水素カルシウム、水酸化マグネシウム、水酸化カルシウム等が挙げられる。
【００３７】
塩基の使用量は、通常ジハロゲン置換アリール化合物もしくは複素環式化合物１モルに対して２〜１０モル、好ましくは２〜５モル倍の範囲である。
【００３８】
反応温度は、通常、室温〜反応系の沸点温度の範囲、好ましくは室温〜１００℃の範囲である。
【００３９】
このような反応により、一般式（１）で示されるチオフェン誘導体類を得ることができ、該チオフェン誘導体類を含む反応混合物を、ろ過、中和、抽出、濃縮、消化、再結晶、カラムクロマトグラムなどの一般的な処理操作を適宜組み合わせることにより、目的とするチオフェン誘導体類を単離することができる。
【００４０】
次に、本発明のチオフェン誘導体類を用いた有機電界発光素子について説明する。
図１は、本発明の有機電界発光素子の一実施形態を示す概念図である。
この例で示す有機電界発光素子は、透明基板（１）、導電性材料からなる陽極（２ａ）、有機化合物からなる正孔輸送層（３）、有機化合物などからなる発光層（４）、有機化合物などからなる電子輸送層（５）および陰極（２ｂ）が順次積層された構造からなっている。
【００４１】
ここで、透明基板としては通常ガラス、透明プラスチックなどが使用される。
また、この例においては、陽極（２ａ）としては厚さ１１０ｎｍ程度に積層された導電性材料であるＩＴＯが使用されている。
また、陰極（２ｂ）としては、マグネシウムと銀の共蒸着により厚さ１１０ｎｍ程度に製幕して得られる半透明の仕事関数が小さな合金（代表的にはＭｇＡｇ／Ａｇ）が使用されている。
【００４２】
正孔輸送層（３）中に含まれる化合物としては、例えば次式

で示される４，４’−ビス−（α−ナフチルフェニルアミノ）ビフェニル（以下、α−ＮＰＤという）等が挙げられ、これらは通常５０ｎｍ程度の厚さに成膜して用いられる。
【００４３】
発光層（４）中に含まれる化合物としては、例えばリン光発光ホスト材料として次式

で示される４，４’−ビスカルバゾリルビフェニル（以下、ＣＢＰという）などと次式

で示されるリン光発光ゲスト材料としてのトリストリ（２−フェニルピリジン）イリジウム錯体（以下、Ｉｒ（ｐｐｙ）_３という）等が挙げられ、これらは上記のＣＢＰに対して６重量％程度添加し、両化合物を２０ｎｍを程度の厚さに成膜して用いられる。
【００４４】
上記の基本構造において、電子輸送層に含まれる電子輸送材料としては、前記したような各種の電子輸送材料例えばＡｌｑ_３などが挙げられるが、本発明の有機電界素子の一実施態様においては、かかる電子輸送層の電子輸送材料として前記本発明の前記一般式（１）で示されるチオフェン誘導体類を用いることができ、これらは通常１０ｎｍ程度の厚さに製膜して用いられる。
【００４５】
あるいは、本発明の有機電界発光素子の第二の実施態様としては、図１の構成において、発光層（４）として本発明の前記一般式（１）で示されるチオフェン誘導体類を厚さ２０ｎｍ程度に製幕して使用し、電子輸送材料としてＡｌｑ_３などの従来公知の電子輸送材料を４０ｎｍ程度に製幕して用いることもできる。
【００４６】
あるいは、本発明の有機電界発光素子の第三の実施態様として、図２に示すように、本発明の前記一般式（１）で示されるチオフェン誘導体類を含む層を第一の電子輸送層（５−１）とし、これに従来のＡｌｑ_３などからなる電子輸送層（５−２）を第二の電子輸送層として両層が積層された構成であってもよい。
【００４７】
更に、本発明の有機電界発光素子のその他の実施態様として、図３に示すように、本発明の前記一般式（１）で示されるチオフェン誘導体類を発光層および電子輸送層を兼ねた発光・電子輸送層（６）とした構成とすることもできる。
【００４８】
尚、本発明の前記一般式（１）で示されるチオフェン誘導体類とともに使用される正孔輸送層、発光層および電子輸送層として使用される化合物は、前記例示化合物に限られず、従来から当該分野において使用されている各種の化合物が適宜使用され、また、各層にはそれぞれの目的に照らして当該化合物以外の他の有機化合物が含まれていてもよい。
同様に、上記各層の厚みについても上記に限定されず、最適の厚みとなるように適宜設定される。
【００４９】
【発明の効果】
本発明のチオフェン誘導体は、有機電界発光素子としてホールブロック能に優れるとともに低電圧駆動下においても十分な発光輝度を有するのみならず、電子輸送層を形成させるための真空蒸着膜における製膜性に優れ、該化合物を電子輸送材料として用いることにより上記性能を有する有機電界発光素子を得ることができる。
【００５０】
【実施例】
次に、実施例により本発明を詳細に説明するが、本発明は下記の実施例に限定されるものではない。
尚、以下の実施例において、発光能の測定にはアジレント・テクノロジー・インク社製のＡｇｉｌｅｎｔ ４１５５Ｃ ｓｅｍｉｃｏｎｄｕｃｔｏｒ ｐａｒａｍｅｔｅｒ ａｎａｌｙｚｅｒおよびニューポート社製のＭｕｌｔｉ−ｆｕｎｃｔｉｏｎ ｏｐｔｉｃａｌ ｍｅｔｅｒを使用した。
【００５１】
【実施例１】
２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンの合成
３，４−ジフェニルチオフェン２．０ｇ（８．４６ｍｍｏｌ）の無水テトラヒドロフラン（以下、ＴＨＦと略記する）３０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌ のノルマルブチルリチウムヘキサン溶液８．０ｍｌ（１２．７ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４ ｍｌ（１９．０ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール８ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去し、残渣をジメチルホルムアミド（以下、ＤＭＦと略記する）５０ｍｌに溶解した。ついで２，６−ジクロロピラジン０．３２ｇ（２．１１ｍｍｏｌ）、炭酸ナトリウム０．６７ｇ（６．３２ｍｍｏｌ）、イオン交換水１０ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．０８３ｇ（０．１０ｍｍｏｌ）を加え８０゜Ｃで１３時間攪拌した。反応終了後、反応液を０゜Ｃまで冷却し析出物を濾過した。濾残をクロロホルムに溶解させ、フロリジルカラムにより金属触媒を除去した。そのクロロホルム溶液をメタノール３００ｍｌ中へ滴下し析出した結晶を濾過し、２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンの白色固体を０．９１ｇ（収率７９％）得た。
得られた２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンは、空気中において安定であった。
この２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンのＰＬ（Ｐｈｏｔｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）を測定したところ、４２８ｎｍに極大吸収を示した。また、ＨＯＭＯおよびＬＵＭＯレベルはそれぞれ６．０ｅＶ，３．０ｅＶであった。
【００５２】
^１Ｈ−ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：７．６９（ｓ，２Ｈ）、７．５２（ｓ，２Ｈ）、７．３１（ｍ，６Ｈ）、７．２１（ｍ，６Ｈ）、７．１７（ｍ，４Ｈ）、７．１０（ｍ，４Ｈ）
^１３Ｃ−ＮＭＲ（１００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：１４７．８、１４４．４、１４０．１、１３９．５、１３８．３、１３６．３、１３５．９、１３０．２、１２８．９、１２８．８、１２８．０、１２７．９、１２６．９、１２６．２
ＤＩＭＳ（ＥＩ）ｍ／ｚ：５４８［Ｍ＋］
ＩＲ（ｃｍ^−１）λ：３４３４、３０５６、１６００、１５１３、１４５０、１１７６、１０７２、１０２７、８７７、７５２、６９８
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：２６４゜Ｃ
【００５３】
【実施例２】
２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジンの合成
３，４−ジフェニルチオフェン３．０ｇ（１２．７ｍｍｏｌ）の無水ＴＨＦ３０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌのノルマルブチルリチウムヘキサン溶液１２．０ｍｌ（１９．０ ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４５ｍｌ（１９．０ ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール１２ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去して、残渣をＤＭＦ６５ｍｌに溶解した。ついで、２，６−ジブロモピリジン１．３５ｇ（５．７１ｍｍｏｌ）、炭酸ナトリウム２．３ｇ（２１．４ｍｍｏｌ）、イオン交換水１０ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．１２５ｇ（０．１５ｍｍｏｌ）を加えて８０゜Ｃで１．５時間攪拌した。反応終了後、反応液を０゜Ｃまで冷却し、析出物を濾過した。濾残をクロロホルムに溶解させ、フロリジルカラムにより金属触媒を除去した。そのクロロホルム溶液をメタノール３００ｍｌ中へ滴下し、析出した結晶を濾過して２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジンの黄白色固体を２．５６ｇ（収率８２％）得た。
得られた２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジンは、空気中において安定であった。
この２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジンのＰＬ（Ｐｈｏｔｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）を測定したところ、３９６ｎｍに極大吸収を示した。
【００５４】
^１Ｈ−ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：７．４３（ｓ，２Ｈ）、７．２９（ｓ，６Ｈ）、７．１８（ｍ，１０Ｈ）、７．０９（ｍ、４Ｈ）、６．９９（ｔ、Ｊ＝８．０Ｈｚ、１Ｈ）、６．４８（ｄ、Ｊ＝８．０Ｈｚ、２Ｈ）^１３Ｃ−ＮＭＲ（１００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：１５２．２、１４４．２、１４１．４、１３８．７、１３６．７、１３６．６、１３５．９、１３０．４、１２８．９、１２８．６、１２７．９、１２７．４、１２６．６、１２５．０、１１９．３
ＬＣＭＳ（ＥＳＩ）ｍ／ｚ：５４８［Ｍ＋１］、５１４、３１２
ＩＲ（ｃｍ^−１）λ：３４３６、３０５４、１５６２、１４５７、１０７２、１０２７、９０６、８０４、７５４、６９８
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：２５７゜Ｃ
【００５５】
【実施例３】
４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジンの合成
３，４−ジフェニルチオフェン４．０ｇ（１６．９ｍｍｏｌ）の無水ＴＨＦ５０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌのノルマルブチルリチウムヘキサン溶液１５．９ｍＬ（２５．４ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４５ｍｌ（１９．０ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール１６ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去して、残渣をＤＭＦ７０ｍｌに溶解した。ついで、４，６−ジクロロピリミジン１．１３ｇ（７．６１ｍｍｏｌ）、炭酸ナトリウム２．４２ｇ（２２．８ｍｍｏｌ）、イオン交換水２０ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．１６７ｇ（０．２１ｍｍｏｌ）を加えて８０゜Ｃで１２時間攪拌した。反応終了後、反応液をクロロホルムで抽出し、有機層を無水硫酸ナトリウムで乾燥させ、その溶液をフロリジルカラムに通して触媒を除去した後、濃縮した。
得られた残渣にＤＭＦを加えてよくかき混ぜ、結晶を濾過した。濾残をメタノールで洗浄し、４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジンの黄色固体を１．７１ｇ （収率４６％）得た。
得られた４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジンは、空気中において安定であった。
この４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジンのＰＬ（Ｐｈｏｔｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）を測定したところ、４０５ｎｍに極大吸収を示した。また３００Ｋにおいて、５５０ｎｍの極大吸収波長を有するリン光が観測された。
【００５６】
^１Ｈ−ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：９．０５（ｄ，Ｊ＝１．８Ｈｚ，１Ｈ）、７．４３（ｓ，２Ｈ）、７．１２−７．２３（ｍ，１２Ｈ）、６．９４−６．９８（ｂｒｏａｄ ｄ，Ｊ＝８．０Ｈｚ，４Ｈ）、６．７８−６．８０（ｄｄ，Ｊ＝８．０，６．６Ｈｚ，４Ｈ）、６．４８（ｄ，Ｊ＝１．４Ｈｚ，１Ｈ）
^１３Ｃ−ＮＭＲ（１００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：１５９．４、１５８．５，１４４．６，１４１．４、１３８．３、１３６．１、１３５．０、１２９．９、１２８．８、１２８．７、１２７．９、１２７．４、１２６．９、１２６．５、１１５．６
ＬＣＭＳ（ＥＳＩ）ｍ／ｚ：５４９［Ｍ＋１］、５２２、５０４
ＩＲ（ｃｍ^−１）λ：３４３８、３０５４、１５６９、１５０４、１４６１、１０７２、１０２７、９１６、７５２、６９６
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：２６１−２６４゜Ｃ
【００５７】
【実施例４】
３，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリダジンの合成
３，４−ジフェニルチオフェン４．０ｇ （１６．９ｍｍｏｌ）の無水ＴＨＦ５０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌ のノルマルブチルリチウムヘキサン溶液１５．９ｍｌ（２５．４ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４５ｍｌ（１９．０ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール１６ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去して、残渣をＤＭＦ７０ｍｌに溶解した。ついで、３，６−ジクロロピリダジン１．１０ｇ（７．６１ｍｍｏｌ）、炭酸ナトリウム２．４２ｇ（２２．８ｍｍｏｌ）、イオン交換水２０ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．１６７ｇ（０．２１ｍｍｏｌ）を加えて８０℃で２時間攪拌した。
反応終了後、反応液を酢酸エチルで抽出し、有機層を無水硫酸ナトリウムで乾燥させて溶媒を減圧留去した。残渣をシリカゲルカラム（クロロホルム：ノルマルヘキサン＝１：１）により精製した。さらに得られた結晶にメタノール６０ｍｌとＤＭＦ６０ｍｌを加えて結晶を洗浄した。固体を濾取し、３，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリダジンの白色固体を０．６５９ｇ（収率１６％）得た。
得られた３，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリダジンは、空気中において安定であった。
【００５８】
^１Ｈ−ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：７．４７（ｓ，２Ｈ）、７．１６−７．２６（ｍ，１２Ｈ）、７．０５−７．０９（ｍ，８Ｈ）、６．４４（ｓ，２Ｈ）
^１３Ｃ−ＮＭＲ（１００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：１５４．１、１４４．０、１４０．３、１３７．１、１３６．２、１３５．６、１３０．３、１２８．９、１２８．７、１２８．０、１２７．８、１２６．９、１２６．２、１２３．７
ＤＩＭＳ ｍ／ｚ：５４８［Ｍ＋］、２７４
ＩＲ（ｃｍ^−１）λ：３４３０、３０５４、１６００、１５４４、１５４０、１３８６、１０７６、１０２７、９０８、８４４、７５２、７００
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：２７２゜Ｃ
【００５９】
【実施例５】
１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンの合成
３，４−ジフェニルチオフェン４．０ｇ（１６．９ｍｍｏｌ）の無水ＴＨＦ５０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌのノルマルブチルリチウムヘキサン溶液１．５９ｍｌ（２５．４ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４５ｍｌ（１９．０ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール１６ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去して、残渣ＤＭＦ７０ｍｌに溶解した。ついで、１，３−ジブロモベンゼン１．８ｇ（７．６１ｍｍｏｌ）、炭酸ナトリウム２．４２ｇ（２２．８ｍｍｏｌ）、イオン交換水２０ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．１６７ｇ（０．２１ｍｍｏｌ）を加えて８０゜Ｃで２時間攪拌した。
反応終了後、析出物を濾取し、イオン交換水１５０ｍｌを加えて超音波洗浄し、析出物中の無機塩を溶出させた。固体を濾取したのち、さらにノルマルヘキサン１５０ｍｌを加えて未反応の３，４−ジフェニルチオフェンを溶出させて固体を濾取し、１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンの白色固体を０．８１３ｇ（収率２０％）得た。
得られた１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンは、空気中において安定であった。
この１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンのＰＬ（Ｐｈｏｔｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）を測定したところ、３７０ｎｍに極大吸収を示した。
【００６０】
^１Ｈ−ＮＭＲ（４００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：７．２８（ｓ，２Ｈ）、７．１６−７．２３（ｍ，１３Ｈ）、７．０７−７．１３（ｍ，４Ｈ）、６．９５−７．００（ｍ，７Ｈ）
^１３Ｃ−ＮＭＲ（１００ＭＨｚ，ＣＤＣｌ_３，ｐｐｍ）δ：１４３．６、１４０．０、１３７．６、１３６．８、１３５．９、１３４．６、１３０．８、１３０．３、１２９．０、１２８．２、１２８．１、１２８．０、１２７．９、１２６．９、１２６．７、１２２．１
ＤＩＭＳ（ＥＩ）ｍ／ｚ：５４６［Ｍ＋］
ＩＲ（ｃｍ^−１）λ：３４３６、３０５４、１５９８、１５０９、１４７７、１４４０、１０７４、１０２６、９１２、８９４、７４８、６９６
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：２３４−２３６゜Ｃ
【００６１】
【実施例６】
２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンの合成
アルゴン雰囲気下に、３，４−ジフェニル−２−（２−キノリル）チオフェン０．５ｇ（１．４ｍｍｏｌ）を無水ＴＨＦ１５ｍｌに溶解させ、−６０゜Ｃに冷却した後１５％ノルマルブチルリチウムヘキサン溶液０．９ｍｌ（１．５ｍｍｏｌ）を滴下する。同温度下に１５分間攪拌後、トリメトキシボラン０．２ｍｌ（１．７ｍｍｏｌ）を滴下し、−６０゜Ｃに保持したまま更に１時間攪拌する。アルゴン雰囲気下にテトラキス（トリフェニルホスフィン）パラジウム（０）０．１６ｇ（０．１４ｍｍｏｌ）、１，４−ジブロモ−２，５−ジメトキシベンゼン０．２２ｇ（０．６９ｍｍｏｌ）、１，４−ジオキサン２０ｍｌ及び水２ｍｌをガラス製フラスコに仕込み、８２゜Ｃに昇温後、−６０゜ＣにてＴＨＦ溶液を注入し２．５時間還流させる。
室温まで冷却した後、水１５ｍｌを加え、析出した固体を濾別する。この固体をシリカゲルカラムクロマトグラフィーにより精製し、２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンを７０ｍｇ（収率１２％）を得た。
得られた２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンは、空気中において安定であった。この２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンのＰＬ（Ｐｈｏｔｏ Ｌｕｍｉｎｅｓｃｅｎｃｅ）を測定したところ、４８８ｎｍに極大吸収を示した。また、ＨＯＭＯおよびＬＵＭＯレベルはそれぞれ５．８ｅＶ，２．６ｅＶであった。
【００６２】
^１Ｈ−ＮＭＲ（ＣＤＣｌ_３，ｐｐｍ）δ：８．０９（ｄ，Ｊ＝８．７Ｈｚ，２Ｈ）、７．７７（ｄ，Ｊ＝８．７Ｈｚ，２Ｈ）、７．６８（ｄｄ，Ｊ＝８．０，１．３Ｈｚ，２Ｈ）、７．６８（ｄｄ，Ｊ＝８．０，１．３Ｈｚ，２Ｈ）、７．４６（ｄｄ，Ｊ＝７．５，６．８Ｈｚ，２Ｈ）、７．２２（ｍ，６Ｈ）、７．１４（ｄｄ，Ｊ＝８．０，１．６Ｈｚ，４Ｈ）、７．０８（ｍ，６Ｈ）、６．９１（ｍ，４Ｈ）、６．８６（ｄ，Ｊ＝８．７Ｈｚ，２Ｈ）、６．６０（ｓ，２Ｈ）３．２６（ｓ，６Ｈ）
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：３４５゜Ｃ
ＤＩ／ＭＳ（ＥＩ）：８６１
極大吸収波長：３７７，２７７ｎｍ
【００６３】
【実施例７】
１，４−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンの合成
３，４−ジフェニルチオフェン２．０ｇ（８．４６ｍｍｏｌ）の無水ＴＨＦ３０ｍｌ溶液を−３０゜Ｃに冷却し、１．５９ｍｏｌ／Ｌのノルマルブチルリチウムヘキサン溶液８．０ｍｌ（１２．７ｍｍｏｌ）を加えた。２時間攪拌した後、トリメトキシボラン１．４５ｍｌ（１９．０ｍｍｏｌ）を加え、さらに−３０゜Ｃで２時間攪拌した。反応液にメタノール８ｍｌを同温で加え、その後室温まで昇温した。反応液中のＴＨＦ及びメタノールを減圧留去して、残渣をＤＭＦ６５ｍｌに溶解した。ついで、１，４−ジブロモベンゼン０．８２０ｇ（３．４６ｍｍｏｌ）、炭酸ナトリウム２．２０ｇ（２０．８ｍｍｏｌ）、イオン交換水１６ｍｌおよびジシクロ［１，１′−ビス（ジフェニルフォスフィノ）フェロセン］パラジウム（ＩＩ）−ジクロロメタン０．１４１ｇ（０．１７ｍｍｏｌ）を加えて８０゜Ｃで２時間攪拌した。
反応終了後析出物を濾取し、イオン交換水１５０ｍｌを加えて超音波洗浄し、析出物中の無機塩を溶出させた。固体を濾取したのち、さらにノルマルヘキサン を１５０ｍｌを加えて未反応の３，４−ジフェニルチオフェンを溶出させて固体を濾取し、白色固体である１，４−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼン０．６３８ｇ（収率１５％）を得た。
得られた１，４−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンは、空気中において安定であった。
【００６４】
ＤＩＭＳ（ＥＩ）ｍ／ｚ：５４６［Ｍ＋］
ＩＲ（ｃｍ^−１）λ：３３９２、３０５４、１６００、１５４２、１５０２、１４４０、１０７４、１０２０、９０２、８３８、７５０、６９８
Ｍｅｌｔｉｎｇ Ｐｏｉｎｔ：測定不能（３００ ℃以上）
【００６５】
【実施例８】
ＩＴＯ薄膜（陽極）がコートされているガラス基板（三容真空工業株式会社製）の上に、真空蒸着法により正孔輸送層としてα−ＮＰＤを４０ｎｍ、Ｉｒ（ｐｐｙ）_３を６重量％ドーピングした発光ホスト材料ＣＢＰの層を２０ｎｍ積層し、電子輸送層として、実施例１で得られた２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジン層を２０ｎｍ、さらにＡｌｑ_３層を４０ｎｍ蒸着した。最後にこの有機層の上に陰極として１２０ｎｍのマグネシウムと銀の合金電極（以下、ＭｇＡｇ／Ａｇと略記する）層を蒸着して素子を完成させた。
この素子に電圧を印加したところ、電流密度１ｍＡ／ｃｍ^２において、６．０ｌｍ／Ｗ以上の発光効率、４．６％以上の外部量子効率が観測された。
【００６６】
【実施例９】
実施例８における２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンに代えて実施例２で得た２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリジンを使用する以外は実施例８に準ずる方法で有機ＥＬ素子を作成した。
電流密度０．７ｍＡ／ｃｍ^２において、５．５ｌｍ／Ｗ以上の発光効率、４．０％以上の外部量子効率が観測された。
【００６７】
【実施例１０】
実施例８における２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンに代えて実施例３で得た４，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリミジンを使用する以外は実施例８に準ずる方法で有機発光素子を作成した。
電流密度０．３ｍＡ／ｃｍ^２において、６．５ｌｍ／Ｗ以上の発光効率、４．５％以上の外部量子効率が観測された。
【００６８】
【実施例１１】
実施例８における２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンに代えて実施例４で得た３，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピリダジンを使用する以外は実施例８に準ずる方法で有機発光素子を作成した。
電流密度１ｍＡ／ｃｍ^２において、３．２ｌｍ／Ｗ以上の発光効率、２．４％以上の外部量子効率が観測された。
【００６９】
【実施例１２】
実施例８における２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンに代えて実施例５で得た１，３−ビス（３，４−ジフェニルチオフェン−２−イル）ベンゼンを使用する以外は実施例８に準ずる方法で有機発光素子を作成した。
電流密７ｍＡ／ｃｍ^２において、２．５ｌｍ／Ｗ以上の発光効率、２．５％以上の外部量子効率が観測された。
【００７０】
【実施例１３】
実施例８における２，６−ビス（３，４−ジフェニルチオフェン−２−イル）ピラジンに代えて実施例６で得た２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンを使用する以外は実施例８に準ずる方法で有機発光素子を作成した。
電流密度２ｍＡ／ｃｍ^２において、３．０ｌｍ／Ｗ以上の発光効率、３．２％以上の外部量子効率が観測された。
【００７１】
【実施例１４】
ＩＴＯ薄膜（陽極）がコートされているガラス基板（三容真空工業株式会社製）の上に、真空蒸着法により正孔輸送層としてα−ＮＰＤを５０ｎｍ、発光層として実施例６で得た２，５−ジメトキシ−１，４−ビス［３，４−ジフェニル−５−（２−キノリル）チオフェン−５−イル］ベンゼンを２０ｎｍ、電子輸送層としてＡｌｑ_３を４０ｎｍそれぞれ蒸着した。最後にこの有機層の上に、陰極として、マグネシウムと同時に銀を共蒸着し、１１０ｎｍのＭｇＡｇ／Ａｇ層を蒸着して素子を完成させた。
この素子に電圧を印加したところ、電流密度１ｍＡ／ｃｍ^２において、１．０ｌｍ／Ｗ以上の発光効率、０．８％以上の外部量子効率が観測された。
【００７２】
【発明の効果】
本発明のチオフェン誘導体類は、有機電界発光素子としてホールブロック能に優れるとともに低電圧駆動下においても十分な発光輝度を有するのみならず、電子輸送層あるいは発光層を形成させるための真空蒸着膜における製膜性に優れ、電子輸送材料あるいは発光材料として用いることにより優れた有機電界発光素子を得ることができる。
【図面の簡単な説明】
【図１】本発明の有機電界発光素子の一実施態様を示す概念図である。
【図２】本発明の有機電界発光素子の第二の実施態様を示す概念図である。
【図３】本発明の有機電界発光素子の他の実施態様を示す概念図である。
【符号の説明】
１：透明基板
２Ａ：陽極
２Ｂ：陰極
３：正孔輸送層
４：発光層
５：電子輸送層
５−１：電子輸送層
５−２：電子輸送層
６：発光電子輸送層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel thiophene derivative, a method for producing the same, and an organic electroluminescent device using the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the diversification of information devices, there has been an increasing need for a flat display element having a smaller power consumption and a smaller space occupation area than a Cathode Ray Tube (so-called CRT). Attention has been focused on organic electroluminescent devices (organic EL devices) having high conversion efficiency, and various materials and organic electroluminescent devices have been proposed.
[0003]
As a basic structure of an organic electroluminescent element, particularly an organic EL element, for example, an anode is provided on a transparent substrate such as glass or plastic, and a hole transport layer and a light-emitting electron transport layer that combines light emission and electron transport are provided thereon. The layers are sequentially laminated and a cathode is provided thereon. Alternatively, a light-emitting layer and an electron transport (electron injection) layer are provided as different compound layers, and holes are provided on an anode provided on a transparent substrate. A transport layer, a light-emitting layer, and an electron transport (electron injection) layer are sequentially laminated, and a cathode is provided thereon.
[0004]
In such an organic electroluminescent device, a transparent electrode made of, for example, conductive Indium-Tin-Oxide (hereinafter abbreviated as ITO) is used as an anode, and the ITO or an alloy electrode of magnesium and silver is used as a cathode. (Hereinafter, referred to as MgAg / Ag) is often used.
[0005]
When a voltage is applied between both electrodes of such an organic electroluminescent device, a current flows through each layer of hole transport, light emission, and electron transport, and a light-emitting phenomenon occurs due to recombination of holes and electrons in the light-emitting layer. Light transmitted through the transparent electrode and the transparent substrate in the thickness direction is irradiated to the outside, and 100 to 10,000 candela / m by applying a voltage of about 10V.²Because it can emit light with extremely high brightness, it is attracting attention as a promising candidate for next-generation display elements.
[0006]
In such an organic electroluminescent device, a tris (8-quinolinolato) aluminum complex (so-called Alq) is used as an electron transporting material for forming an electron transporting layer.₃), Oxadiazole zinc complex (so-called Zn (ODZ)₂), Benzothiazole zinc complex (so-called Zn (BTZ)₂), Benzoxazole zinc complex (so-called Zn (BOX)₂), 5-hydroxyflavone beryllium complex (so-called Be (5Fla)₂), Tris (8-quinolinolato) bismuth complex (so-called Biq), biphenylbis (8-quinolinolato) aluminum complex (so-called BAlq), and other various metal complexes that are also used as light-emitting materials are known (for example, Patent Documents). However, these methods have a problem that the organic EL device can be driven at a relatively low voltage, but the hole blocking ability is low.
[0007]
Compounds other than the metal complex include 1,3-bis (phenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (so-called OXD-7) and 2- ( 4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (so-called PBD), 1-phenyl-2-biphenyl-5-t-butylphenyltriazole (so-called TAZ) Such heterocyclic compounds are known. (See, for example, Non-Patent Document 1, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6), but these have a problem that the driving voltage is high, and they do not have sufficient performance for practical use. I couldn't say it.
[0008]
[Patent Document 1]
JP-A-59-194393
[Patent Document 2]
JP-A-11-307260
[Patent Document 3]
JP-A-5-152027
[Patent Document 4]
JP-A-5-202011
[Patent Document 5]
JP-A-6-92947
[Patent Document 6]
JP-A-6-145658
[Non-patent document 1]
Journal of the Chemical Society of Japan, 11, 1540 (1991)
[0009]
As described above, the electron transporting material or the luminescent electron transporting material used in the conventional organic electroluminescent device as described above has a problem in a hole blocking layer, a driving voltage, and the like. The development of an electron transporting material or a luminescent material which is not only excellent in performance but also has sufficient emission luminance even under low voltage driving, and also has excellent curtain-making properties in a vacuum evaporation curtain for forming an electron transporting layer or a luminescent layer. Wanted.
[0010]
[Problems to be solved by the invention]
From these facts, the present inventors have solved the problem of the organic electroluminescent device which has been conventionally known, and have excellent hole blocking ability as an organic electroluminescent device and have sufficient light emission luminance even under low voltage driving. In addition to having a compound having excellent film forming properties in a vacuum deposited film for forming an electron transporting layer or a light emitting electron transporting layer, an organic electroluminescent device using the compound as an electron transporting material or a light emitting material As a result of studying to develop the present invention, the present invention has been reached.
[0011]
[Means for Solving the Problems]
A first aspect of the present invention is the following general formula (1)

[Wherein, R¹And R²Represents the same or different and each represents a hydrogen atom, an alkyl group or an alkoxy group;³Represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a heterocyclic group, and -Ar- represents the following formula (2)

(Where R⁴Represents an alkyl group, and m is an integer of 0 to 3. )
Or the following formula (3)

(Where R⁵Represents an alkyl group, and n is an integer of 0 to 2. )
Or the following formula (4)

(Where R⁶Represents an alkyl group, and p is an integer of 0 to 2. )
Or the following formula (5)

(Where R⁷Represents an alkyl group, and q is an integer of 0 to 2. )
Or the following formula (6)

(Where R⁸Represents an alkyl group, and r is an integer of 0 to 2. )
Indicates one of ]
And thiophene derivatives represented by the formula:
[0012]
A second aspect of the present invention is to provide the following general formula (7)

(Where R¹, R²And R³Is the same as above. )
Is reacted with an alkyl lithium, and the resulting reaction mixture is added to the following general formula (8)
B (OR⁹)₃
(Where R⁹Represents an alkyl group. )
And reacting with the addition of a trialkoxyborane represented by the following general formula (9)

(Where R¹, R², R³And R⁹Is the same as above. )
To obtain a dialkoxythienylborane represented by the following general formula (10)
X-Ar-X
[In the formula, X represents a halogen atom, and -Ar- is the same as the formulas (2) to (6). ]
Characterized by reacting the compound with a dihalogen-substituted aryl compound or heterocyclic compound represented by the formula (I) in a solvent in the presence of a palladium catalyst and a base. It is.
[0013]
Further, a third aspect of the present invention is to provide an organic electroluminescent device having an organic layer containing a thiophene derivative represented by the general formula (1).
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In the thiophene derivatives represented by the general formula (1), the substituent R¹And R²Are the same or different and each is a hydrogen atom, an alkyl group or an alkoxy group, and the alkyl group is a linear group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group. A branched or branched lower alkyl group having 1 to 4 carbon atoms, and an alkoxy group includes a methoxy group, an ethoxy group, an n-propoxy group and an n-butoxy group, and a hydrogen atom is particularly preferable. It is.
[0015]
Substituent R³Is a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a heterocyclic group, wherein the alkyl group is exemplified by the same alkyl groups as described above, and the aralkyl group refers to a hydrogen atom of these alkyl groups as an aryl group. A substituted group, specifically, a benzyl group, a methylbenzyl group, a phenethyl group, a naphthylmethyl group, a diphenylmethyl group, etc., and an aryl group may be an aromatic hydrocarbon which may have a substituent Examples of the group include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a methylnaphthyl group, and examples of the heterocyclic group include a pyridyl group, a quinolyl group, and an isoquinolyl group.
[0016]
In the substituents -Ar- represented by the formulas (2), (3), (4), (5) and (6), R in each formula⁴, R⁵, R⁶, R⁷And R⁸The alkyl group represented by is the same as described above.
[0017]
The thiophene derivatives (1) of the present invention include the substituent R in the general formula (1).¹And R²Are all hydrogen atoms and the substituent R³Is a hydrogen atom or a heterocyclic group, and the substituent -Ar- is represented by the above formulas (2) to (5);⁴, R⁵, R⁶Or R⁷M, n, p and q indicating the number of are 0, or a thiophene derivative in which the substituent -Ar- is represented by the formula (6) is preferable.
[0018]
Examples of such thiophene derivatives (1) include 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine and 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine 4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine, 3,6-bis (3,4-diphenylthiophen-2-yl) pyridazine, 1,3-bis (3,4-diphenyl) Thiophene-2-yl) benzene, 1,4-bis (3,4-diphenylthiophen-2-yl) benzene, 2,5-dimethoxy-1,4-bis [3,4-diphenyl- (2-quinolyl) Thiophene-5-yl] benzene and the like can be specifically mentioned, but it is not limited to these exemplified compounds.
[0019]
Such a thiophene derivative of the present invention represented by the general formula (1) is obtained by, for example, reacting an arylthiophene represented by the general formula (4) with an alkyllithium, and then reacting the arylthiophene represented by the general formula (5). And then reacting with a halogen-substituted aryl compound or heterocyclic compound represented by the general formula (7) in the presence of a palladium catalyst.
[0020]
Hereinafter, this manufacturing method will be described in detail.
As the arylthiophene represented by the general formula (4), which is a reaction raw material, a compound corresponding to a target thiophene derivative is selectively used. For example, 3,4-diphenylthiophene, 3,4-diphenyl-2- ｛ Examples include, but are not limited to, 2-pyridyldithiophene.
[0021]
Examples of the alkyl lithium include ethyl lithium, n-propyl lithium, n-butyl lithium and the like, and n-butyl lithium is preferably used in terms of handleability and reactivity.
[0022]
The reaction between the arylthiophene represented by the general formula (4) and the alkyl lithium is usually performed in an organic solvent.
The organic solvent is not particularly limited as long as it is inert to the reaction, and examples thereof include dimethoxyethane, diethyl ether, ethers such as tetrahydrofuran, hexane, heptane, and aliphatic hydrocarbons such as octane. One or more of these can be used in the reaction.
[0023]
In this reaction, the amount of the lithium alkyl used is usually 0.8 to 2 times, preferably 1 to 1.5 times the molar amount of the arylthiophenes represented by the general formula (4).
The amount of the organic solvent used is not particularly limited, but is generally 1 to 100 times by weight the arylthiophene represented by the general formula (4).
The reaction temperature is usually lower than or equal to room temperature, preferably -80 ° C to 0 ° C.
[0024]
By this reaction, an arylthienolithium represented by the following formula (11) is obtained, in which the 5-position of the thiophene nucleus of the arylthiophene represented by the general formula (4) is substituted with lithium.

(Where R¹, R²And R³Is the same as above. )
[0025]
In this reaction, the alkyllithium and the generated arylthienolithium easily react with water and decompose, so that it is preferable to keep the reaction system substantially anhydrous.
[0026]
Next, the arylthienolithium thus obtained is reacted with a trialkoxyborane represented by the general formula (8) to produce a dialkoxythienoborane represented by the general formula (9).
As a reaction method, after isolating the arylthienolithiums from the reaction mixture, the reaction may be carried out with a trialkoxyborane in the same organic solvent as described above, but usually, the reaction mixture containing the arylthienolithiums is used. The reaction is carried out by adding a trialkoxyborane to the reaction mixture and reacting the arylthienolithium with the trialkoxyborane.
[0027]
Here, in the trialkoxyborane represented by the general formula (8), the substituent R⁹Examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group. And specific examples of trialkoxyboranes include trimethoxyborane, triethoxyborane, and tri-n-propoxyborane.
[0028]
The amount of trialkoxyborane used in this reaction is usually in the range of 1 to 3.5 mol per 1 mol of thiophene as a starting material, and the reaction temperature is usually room temperature, as in the previous reaction. Hereinafter, it is preferably -80 ° C to 0 ° C.
[0029]
After completion of the reaction, an alcohol such as methanol or ethanol is added to the reaction mixture containing the dialkoxythienoborane thus produced, and then the solvent is removed by distillation under reduced pressure.
[0030]
A solvent such as dimethylformamide is added to the residue after distilling off the solvent to dissolve the residue, and the dialkoxythienoborane solution is added with the dihalogen-substituted aryl compound or heterocyclic compound represented by the general formula (10). The coupling reaction is carried out in the presence of a palladium catalyst and a base to obtain the desired thiophene derivative represented by the general formula (1).
[0031]
Here, as the dihalogen-substituted aryl compound or heterocyclic compound represented by the general formula (10), p-dibromobenzene, m-dibromobenzene, 2,6-dichloropyridine, 2,6-dibromopyridine, 2,6 -Dichloropiperidine, 2,6-dichloropyrazine, 4,5-dichloropyrimidine, 4,6-dichloropyrimidine, 3,6-dichloropyridazine, 1,4-dibromo-2,5-dimethoxybenzene, and the like. The amount used is 0.1 to 1 mol times based on the arylthiophenes which are the starting materials.
[0032]
As the palladium catalyst, tetrakis (triphenylphosphine) palladium, dichlorobis (triphenylphosphine) palladium, dichlorobis (triphenylphosphine) palladium, dichloro [bis (diphenylphosphino) ethane] palladium, dichloro [bis (diphenylphosphino) butane Palladium and palladium complexes such as dichloro [bis (diphenylphosphino) ferrocene] palladium can be mentioned, but dichloro [bis (diphenylphosphino) ferrocene] palladium is preferably used.
[0033]
The amount of the palladium catalyst used is such that the metal palladium contained in the catalyst is usually 0.005 to 0.5 mol, preferably 0 to 5 mol per mol of the dihalogen-substituted aryl compound or heterocyclic compound represented by the general formula (10). 0.01 to 0.15 mole times.
[0034]
As the base, known inorganic bases can be widely used, and examples thereof include bases of alkali metal carbonate, alkali metal bicarbonate, alkali metal hydroxide, alkali metal phosphate, alkali metal fluoride, and alkaline earth metal. And these can be used alone or in combination of two or more.
[0035]
Specifically, sodium carbonate, lithium carbonate, cesium carbonate and the like as alkali metal carbonates, sodium hydrogen carbonate, potassium hydrogen carbonate and the like as alkali metal hydrogen carbonate, sodium hydroxide as alkali metal hydroxide, Potassium hydroxide, lithium hydroxide, cesium hydroxide and the like, alkali metal phosphates such as sodium phosphate, potassium phosphate, lithium phosphate, cesium phosphate, etc. Examples thereof include sodium fluoride, potassium fluoride, and cesium fluoride.
[0036]
Examples of the alkaline earth metal basic salts include alkaline earth metal carbonates, hydrogen carbonates, and hydroxides, and specific examples thereof include magnesium carbonate, calcium carbonate, magnesium hydrogen carbonate, and the like. Examples thereof include calcium hydrogen carbonate, magnesium hydroxide, and calcium hydroxide.
[0037]
The amount of the base to be used is generally 2 to 10 mol, preferably 2 to 5 mol, per 1 mol of the dihalogen-substituted aryl compound or heterocyclic compound.
[0038]
The reaction temperature is usually in the range of room temperature to the boiling point of the reaction system, preferably in the range of room temperature to 100 ° C.
[0039]
By such a reaction, a thiophene derivative represented by the general formula (1) can be obtained, and the reaction mixture containing the thiophene derivative is filtered, neutralized, extracted, concentrated, digested, recrystallized, and column chromatogram. The desired thiophene derivatives can be isolated by appropriately combining general processing operations such as the above.
[0040]
Next, an organic electroluminescent device using the thiophene derivative of the present invention will be described.
FIG. 1 is a conceptual diagram showing one embodiment of the organic electroluminescent device of the present invention.
The organic electroluminescent device shown in this example includes a transparent substrate (1), an anode (2a) made of a conductive material, a hole transport layer (3) made of an organic compound, a light emitting layer (4) made of an organic compound, and the like. It has a structure in which an electron transport layer (5) made of a compound or the like and a cathode (2b) are sequentially laminated.
[0041]
Here, glass, transparent plastic or the like is usually used as the transparent substrate.
In this example, as the anode (2a), ITO, which is a conductive material laminated to a thickness of about 110 nm, is used.
Further, as the cathode (2b), an alloy (typically, MgAg / Ag) which is obtained by curtaining to a thickness of about 110 nm by co-evaporation of magnesium and silver and has a small work function is used.
[0042]
As the compound contained in the hole transport layer (3), for example, the following formula

4,4'-bis-([alpha] -naphthylphenylamino) biphenyl (hereinafter referred to as [alpha] -NPD) and the like, which are usually used after being formed into a film having a thickness of about 50 nm.
[0043]
The compound contained in the light emitting layer (4) is, for example, a phosphorescent host material represented by the following formula:

4,4'-biscarbazolylbiphenyl (hereinafter referred to as CBP) represented by the following formula:

Tris (2-phenylpyridine) iridium complex (hereinafter Ir (ppy)) as a phosphorescent guest material represented by₃These are added in an amount of about 6% by weight to the above-mentioned CBP, and both compounds are used after being formed into a film having a thickness of about 20 nm.
[0044]
In the above basic structure, as the electron transporting material contained in the electron transporting layer, various electron transporting materials as described above, for example, Alq₃And the like, but in one embodiment of the organic electric field device of the present invention, a thiophene derivative represented by the general formula (1) of the present invention can be used as the electron transport material of the electron transport layer, These are usually used after forming a film to a thickness of about 10 nm.
[0045]
Alternatively, as a second embodiment of the organic electroluminescent device of the present invention, in the configuration of FIG. 1, a thiophene derivative represented by the above general formula (1) of the present invention having a thickness of about 20 nm is used as a light emitting layer (4). Alq as electron transport material₃It is also possible to use a conventionally known electron-transporting material such as the one produced in about 40 nm.
[0046]
Alternatively, as a third embodiment of the organic electroluminescent device of the present invention, as shown in FIG. 2, a layer containing a thiophene derivative represented by the general formula (1) of the present invention may be a first electron transport layer ( 5-1) and the conventional Alq₃A configuration in which both layers are laminated as an electron transporting layer (5-2) made of the same as a second electron transporting layer may be used.
[0047]
Further, as another embodiment of the organic electroluminescent device of the present invention, as shown in FIG. 3, a thiophene derivative represented by the general formula (1) of the present invention is used as a light emitting layer which also serves as a light emitting layer and an electron transport layer. It can also be configured as an electron transport layer (6).
[0048]
The compounds used as the hole transporting layer, the light emitting layer and the electron transporting layer used together with the thiophene derivative represented by the general formula (1) of the present invention are not limited to the above-mentioned compounds, but have been used in the art. The various compounds used in the above are appropriately used, and each layer may contain other organic compounds other than the compound in view of the purpose.
Similarly, the thickness of each of the above layers is not limited to the above, and is appropriately set so as to have an optimum thickness.
[0049]
【The invention's effect】
The thiophene derivative of the present invention not only has excellent hole blocking ability as an organic electroluminescent device and also has a sufficient emission luminance even under low voltage driving, and also has a good film forming property in a vacuum deposited film for forming an electron transport layer. Excellent, an organic electroluminescent device having the above performance can be obtained by using the compound as an electron transporting material.
[0050]
【Example】
Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.
In the following Examples, the measurement of the luminous ability was performed using an Agilent 4155C semiconductor parameter analyzer and a Multi-function optical meter manufactured by Newport.
[0051]
Embodiment 1
Synthesis of 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine
A solution of 2.0 g (8.46 mmol) of 3,4-diphenylthiophene in 30 ml of anhydrous tetrahydrofuran (hereinafter abbreviated as THF) was cooled to −30 ° C., and 8.0 ml of a 1.59 mol / L normal butyl lithium hexane solution was added. (12.7 mmol) was added. After stirring for 2 hours, 1.4 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 8 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure, and the residue was dissolved in 50 ml of dimethylformamide (hereinafter abbreviated as DMF). Then, 0.32 g (2.11 mmol) of 2,6-dichloropyrazine, 0.67 g (6.32 mmol) of sodium carbonate, 10 ml of ion-exchanged water and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) ) -Dichloromethane (0.083 g, 0.10 mmol) was added, and the mixture was stirred at 80 ° C for 13 hours. After completion of the reaction, the reaction solution was cooled to 0 ° C., and the precipitate was filtered. The residue from the filtration was dissolved in chloroform, and the metal catalyst was removed using a Florisil column. The chloroform solution was dropped into 300 ml of methanol, and the precipitated crystals were filtered to obtain 0.91 g (yield 79%) of 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine as a white solid. .
The obtained 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine was stable in the air.
When the PL (Photo Luminescence) of the 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine was measured, it showed a maximum absorption at 428 nm. The HOMO and LUMO levels were 6.0 eV and 3.0 eV, respectively.
[0052]
¹H-NMR (400 MHz, CDCl₃, Ppm) δ: 7.69 (s, 2H), 7.52 (s, 2H), 7.31 (m, 6H), 7.21 (m, 6H), 7.17 (m, 4H), 7.10 (m, 4H)
^ThirteenC-NMR (100 MHz, CDCl₃, Ppm) δ: 147.8, 144.4, 140.1, 139.5, 138.3, 136.3, 135.9, 130.2, 128.9, 128.8, 128.0, 127 .9, 126.9, 126.2
DIMS (EI) m / z: 548 [M +]
IR (cm^-1) Λ: 3434, 3056, 1600, 1513, 1450, 1176, 1072, 1027, 877, 752, 698
Melting Point: 264 ° C
[0053]
Embodiment 2
Synthesis of 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine
A solution of 3.0 g (12.7 mmol) of 3,4-diphenylthiophene in 30 ml of anhydrous THF was cooled to −30 ° C., and 12.0 ml (19.0 mmol) of a 1.59 mol / L normal butyl lithium hexane solution was added. . After stirring for 2 hours, 1.45 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 12 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure, and the residue was dissolved in 65 ml of DMF. Then, 1.35 g (5.71 mmol) of 2,6-dibromopyridine, 2.3 g (21.4 mmol) of sodium carbonate, 10 ml of ion-exchanged water and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium ( II)-0.125 g (0.15 mmol) of dichloromethane was added, and the mixture was stirred at 80 ° C for 1.5 hours. After the completion of the reaction, the reaction solution was cooled to 0 ° C., and the precipitate was filtered. The residue from the filtration was dissolved in chloroform, and the metal catalyst was removed using a Florisil column. The chloroform solution was dropped into 300 ml of methanol, and the precipitated crystals were filtered to obtain 2.56 g of a yellowish white solid of 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine (yield: 82%). Obtained.
The obtained 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine was stable in the air.
When the PL (Photo Luminescence) of the 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine was measured, it showed a maximum absorption at 396 nm.
[0054]
¹H-NMR (400 MHz, CDCl₃, Ppm) δ: 7.43 (s, 2H), 7.29 (s, 6H), 7.18 (m, 10H), 7.09 (m, 4H), 6.99 (t, J = 8) .0 Hz, 1H), 6.48 (d, J = 8.0 Hz, 2H)^ThirteenC-NMR (100 MHz, CDCl₃, 152.2, 144.2, 141.4, 138.7, 136.7, 136.6, 135.9, 130.4, 128.9, 128.6, 127.9, 127 .4, 126.6, 125.0, 119.3
LCMS (ESI) m / z: 548 [M + 1], 514, 312
IR (cm^-1) Λ: 3436, 3054, 1562, 1457, 1072, 1027, 906, 804, 754, 698
Melting Point: 257 ° C
[0055]
Embodiment 3
Synthesis of 4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine
A solution of 4.0 g (16.9 mmol) of 3,4-diphenylthiophene in 50 ml of anhydrous THF was cooled to −30 ° C., and 15.9 mL (25.4 mmol) of a 1.59 mol / L hexane solution of normal butyllithium was added. After stirring for 2 hours, 1.45 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 16 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure, and the residue was dissolved in 70 ml of DMF. Then, 1.13 g (7.61 mmol) of 4,6-dichloropyrimidine, 2.42 g (22.8 mmol) of sodium carbonate, 20 ml of ion-exchanged water and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium ( II)-0.167 g (0.21 mmol) of dichloromethane was added and the mixture was stirred at 80 ° C for 12 hours. After completion of the reaction, the reaction solution was extracted with chloroform, the organic layer was dried over anhydrous sodium sulfate, and the solution was passed through a Florisil column to remove the catalyst, and then concentrated.
DMF was added to the obtained residue, mixed well, and the crystals were filtered. The residue obtained by filtration was washed with methanol to obtain 1.71 g (yield: 46%) of 4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine as a yellow solid.
The obtained 4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine was stable in the air.
When the PL (Photo Luminescence) of this 4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine was measured, it showed a maximum absorption at 405 nm. At 300 K, phosphorescence having a maximum absorption wavelength of 550 nm was observed.
[0056]
¹H-NMR (400 MHz, CDCl₃, Ppm) δ: 9.05 (d, J = 1.8 Hz, 1H), 7.43 (s, 2H), 7.12-7.23 (m, 12H), 6.94-6.98 ( broad d, J = 8.0 Hz, 4H), 6.78-6.80 (dd, J = 8.0, 6.6 Hz, 4H), 6.48 (d, J = 1.4 Hz, 1H)
^ThirteenC-NMR (100 MHz, CDCl₃, 15), 158.5, 144.6, 141.4, 138.3, 136.1, 135.0, 129.9, 128.8, 128.7, 127.9, 127. .4, 126.9, 126.5, 115.6
LCMS (ESI) m / z: 549 [M + 1], 522, 504
IR (cm^-1) Λ: 3438, 3054, 1569, 1504, 1461, 1072, 1027, 916, 752, 696
Melting Point: 261-264 ° C
[0057]
Embodiment 4
Synthesis of 3,6-bis (3,4-diphenylthiophen-2-yl) pyridazine
A solution of 4.0 g (16.9 mmol) of 3,4-diphenylthiophene in 50 ml of anhydrous THF was cooled to −30 ° C., and 15.9 ml (25.4 mmol) of a 1.59 mol / L normal butyl lithium hexane solution was added. After stirring for 2 hours, 1.45 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 16 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure, and the residue was dissolved in 70 ml of DMF. Then, 1.10 g (7.61 mmol) of 3,6-dichloropyridazine, 2.42 g (22.8 mmol) of sodium carbonate, 20 ml of ion-exchanged water and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium ( II)-0.167 g (0.21 mmol) of dichloromethane was added, and the mixture was stirred at 80 ° C for 2 hours.
After completion of the reaction, the reaction solution was extracted with ethyl acetate, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by a silica gel column (chloroform: normal hexane = 1: 1). Further, 60 ml of methanol and 60 ml of DMF were added to the obtained crystals to wash the crystals. The solid was collected by filtration to obtain 0.659 g (yield: 16%) of 3,6-bis (3,4-diphenylthiophen-2-yl) pyridazine as a white solid.
The obtained 3,6-bis (3,4-diphenylthiophen-2-yl) pyridazine was stable in the air.
[0058]
¹H-NMR (400 MHz, CDCl₃, Ppm) δ: 7.47 (s, 2H), 7.16 to 7.26 (m, 12H), 7.05 to 7.09 (m, 8H), 6.44 (s, 2H).
^ThirteenC-NMR (100 MHz, CDCl₃, 154.1, 144.0, 140.3, 137.1, 136.2, 135.6, 130.3, 128.9, 128.7, 128.0, 127.8, 126 .9, 126.2, 123.7
DIMS m / z: 548 [M +], 274
IR (cm^-1) Λ: 3430, 3054, 1600, 1544, 1540, 1386, 1076, 1027, 908, 844, 752, 700
Melting Point: 272 ° C
[0059]
Embodiment 5
Synthesis of 1,3-bis (3,4-diphenylthiophen-2-yl) benzene
A solution of 4.0 g (16.9 mmol) of 3,4-diphenylthiophene in 50 ml of anhydrous THF was cooled to −30 ° C., and 1.59 ml (25.4 mmol) of a 1.59 mol / L normal butyl lithium hexane solution was added. After stirring for 2 hours, 1.45 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 16 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure and dissolved in 70 ml of residual DMF. Next, 1.8 g (7.61 mmol) of 1,3-dibromobenzene, 2.42 g (22.8 mmol) of sodium carbonate, 20 ml of ion-exchanged water, and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium ( II)-0.167 g (0.21 mmol) of dichloromethane was added, and the mixture was stirred at 80 ° C for 2 hours.
After the completion of the reaction, the precipitate was collected by filtration, 150 ml of ion-exchanged water was added thereto, and the mixture was subjected to ultrasonic washing to elute inorganic salts in the precipitate. After the solid was collected by filtration, 150 ml of normal hexane was further added to elute unreacted 3,4-diphenylthiophene, and the solid was collected by filtration to obtain 1,3-bis (3,4-diphenylthiophen-2-yl). 0.813 g (20% yield) of a white solid of benzene was obtained.
The obtained 1,3-bis (3,4-diphenylthiophen-2-yl) benzene was stable in the air.
When PL (Photo Luminescence) of the 1,3-bis (3,4-diphenylthiophen-2-yl) benzene was measured, it showed a maximum absorption at 370 nm.
[0060]
¹H-NMR (400 MHz, CDCl₃, Ppm) δ: 7.28 (s, 2H), 7.16 to 7.23 (m, 13H), 7.07 to 7.13 (m, 4H), 6.95 to 7.00 (m, 13H) 7H)
^ThirteenC-NMR (100 MHz, CDCl₃, 143.6, 140.0, 137.6, 136.8, 135.9, 134.6, 130.8, 130.3, 129.0, 128.2, 128.1, 128 0.0, 127.9, 126.9, 126.7, 122.1
DIMS (EI) m / z: 546 [M +]
IR (cm^-1) Λ: 3436, 3054, 1598, 1509, 1477, 1440, 1074, 1026, 912, 894, 748, 696
Melting Point: 234-236 ° C
[0061]
Embodiment 6
Synthesis of 2,5-dimethoxy-1,4-bis [3,4-diphenyl-5- (2-quinolyl) thiophen-5-yl] benzene
Under an argon atmosphere, 0.5 g (1.4 mmol) of 3,4-diphenyl-2- (2-quinolyl) thiophene was dissolved in 15 ml of anhydrous THF, cooled to -60 ° C, and then cooled to a 15% normal butyllithium hexane solution 0. 0.9 ml (1.5 mmol) are added dropwise. After stirring at the same temperature for 15 minutes, 0.2 ml (1.7 mmol) of trimethoxyborane was added dropwise, and the mixture was further stirred for 1 hour while maintaining the temperature at -60 ° C. Under an argon atmosphere, 0.16 g (0.14 mmol) of tetrakis (triphenylphosphine) palladium (0), 0.22 g (0.69 mmol) of 1,4-dibromo-2,5-dimethoxybenzene, 20 ml of 1,4-dioxane Then, 2 ml of water and 2 ml of water were charged into a glass flask, heated to 82 ° C., and then a THF solution was injected at −60 ° C. and refluxed for 2.5 hours.
After cooling to room temperature, 15 ml of water is added, and the precipitated solid is separated by filtration. This solid was purified by silica gel column chromatography to obtain 70 mg of 2,5-dimethoxy-1,4-bis [3,4-diphenyl-5- (2-quinolyl) thiophen-5-yl] benzene (yield: 12%). ) Got.
The obtained 2,5-dimethoxy-1,4-bis [3,4-diphenyl-5- (2-quinolyl) thiophen-5-yl] benzene was stable in the air. When the PL (Photo Luminescence) of this 2,5-dimethoxy-1,4-bis [3,4-diphenyl-5- (2-quinolyl) thiophen-5-yl] benzene was measured, it showed a maximum absorption at 488 nm. Was. The HOMO and LUMO levels were 5.8 eV and 2.6 eV, respectively.
[0062]
¹H-NMR (CDCl₃, Ppm) δ: 8.09 (d, J = 8.7 Hz, 2H), 7.77 (d, J = 8.7 Hz, 2H), 7.68 (dd, J = 8.0, 1.3 Hz) , 2H), 7.68 (dd, J = 8.0, 1.3 Hz, 2H), 7.46 (dd, J = 7.5, 6.8 Hz, 2H), 7.22 (m, 6H). , 7.14 (dd, J = 8.0, 1.6 Hz, 4H), 7.08 (m, 6H), 6.91 (m, 4H), 6.86 (d, J = 8.7 Hz, 2H), 6.60 (s, 2H) 3.26 (s, 6H)
Melting Point: 345 ° C
DI / MS (EI): 861
Maximum absorption wavelength: 377, 277 nm
[0063]
Embodiment 7
Synthesis of 1,4-bis (3,4-diphenylthiophen-2-yl) benzene
A solution of 2.0 g (8.46 mmol) of 3,4-diphenylthiophene in 30 ml of anhydrous THF was cooled to −30 ° C., and 8.0 ml (12.7 mmol) of a 1.59 mol / L solution of normal butyllithium in hexane was added. After stirring for 2 hours, 1.45 ml (19.0 mmol) of trimethoxyborane was added, and the mixture was further stirred at −30 ° C. for 2 hours. 8 ml of methanol was added to the reaction solution at the same temperature, and then the temperature was raised to room temperature. THF and methanol in the reaction solution were distilled off under reduced pressure, and the residue was dissolved in 65 ml of DMF. Subsequently, 0.820 g (3.46 mmol) of 1,4-dibromobenzene, 2.20 g (20.8 mmol) of sodium carbonate, 16 ml of ion-exchanged water and dicyclo [1,1′-bis (diphenylphosphino) ferrocene] palladium ( II)-0.141 g (0.17 mmol) of dichloromethane was added, and the mixture was stirred at 80 ° C for 2 hours.
After the completion of the reaction, the precipitate was collected by filtration, 150 ml of ion-exchanged water was added thereto, and the mixture was subjected to ultrasonic washing to elute inorganic salts in the precipitate. After the solid was collected by filtration, 150 ml of normal hexane was further added to elute unreacted 3,4-diphenylthiophene, and the solid was collected by filtration. White solid 1,4-bis (3,4-diphenylthiophene) was collected. 0.638 g (yield 15%) of -2-yl) benzene was obtained.
The obtained 1,4-bis (3,4-diphenylthiophen-2-yl) benzene was stable in the air.
[0064]
DIMS (EI) m / z: 546 [M +]
IR (cm^-1) Λ: 3392, 3054, 1600, 1542, 1502, 1440, 1074, 1020, 902, 838, 750, 698
Melting Point: Measurement not possible (300 ° C or higher)
[0065]
Embodiment 8
On a glass substrate (manufactured by Sanyo Vacuum Industry Co., Ltd.) coated with an ITO thin film (anode), α-NPD was used as a hole transport layer at a thickness of 40 nm by a vacuum evaporation method, and Ir (ppy) was used.₃And a 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine layer obtained in Example 1 was deposited to a thickness of 20 nm as an electron transporting layer. And also Alq₃The layer was evaporated to 40 nm. Finally, a 120 nm magnesium-silver alloy electrode (hereinafter abbreviated as MgAg / Ag) layer was deposited as a cathode on the organic layer to complete the device.
When a voltage was applied to this device, a current density of 1 mA / cm², A luminous efficiency of 6.0 lm / W or more and an external quantum efficiency of 4.6% or more were observed.
[0066]
Embodiment 9
The 2,6-bis (3,4-diphenylthiophen-2-yl) pyridine obtained in Example 2 was replaced with 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine in Example 8. An organic EL device was prepared in the same manner as in Example 8 except that the device was used.
Current density 0.7 mA / cm², A luminous efficiency of 5.5 lm / W or more and an external quantum efficiency of 4.0% or more were observed.
[0067]
Embodiment 10
4,6-bis (3,4-diphenylthiophen-2-yl) pyrimidine obtained in Example 3 was replaced with 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine in Example 8. An organic light-emitting device was prepared in the same manner as in Example 8 except that it was used.
Current density 0.3 mA / cm², A luminous efficiency of 6.5 lm / W or more and an external quantum efficiency of 4.5% or more were observed.
[0068]
Embodiment 11
3,6-bis (3,4-diphenylthiophen-2-yl) pyridazine obtained in Example 4 was replaced with 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine in Example 8. An organic light-emitting device was prepared in the same manner as in Example 8 except that it was used.
Current density 1mA / cm², A luminous efficiency of 3.2 lm / W or more and an external quantum efficiency of 2.4% or more were observed.
[0069]
Embodiment 12
1,3-bis (3,4-diphenylthiophen-2-yl) benzene obtained in Example 5 was replaced with 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine in Example 8 An organic light-emitting device was prepared in the same manner as in Example 8 except that it was used.
Current density 7mA / cm², A luminous efficiency of 2.5 lm / W or more and an external quantum efficiency of 2.5% or more were observed.
[0070]
Embodiment 13
2,5-Dimethoxy-1,4-bis [3,4-diphenyl-5) obtained in Example 6 in place of 2,6-bis (3,4-diphenylthiophen-2-yl) pyrazine in Example 8 An organic light-emitting device was prepared in the same manner as in Example 8, except that-(2-quinolyl) thiophen-5-yl] benzene was used.
Current density 2mA / cm², An emission efficiency of 3.0 lm / W or more and an external quantum efficiency of 3.2% or more were observed.
[0071]
Embodiment 14
On a glass substrate (manufactured by Sanyo Vacuum Industry Co., Ltd.) coated with an ITO thin film (anode), α-NPD was used as a hole transport layer in a thickness of 50 nm as a hole transport layer and a light emitting layer obtained in Example 6 was obtained by vacuum evaporation. , 5-Dimethoxy-1,4-bis [3,4-diphenyl-5- (2-quinolyl) thiophen-5-yl] benzene at 20 nm and Alq as an electron transport layer₃Was deposited by 40 nm each. Finally, silver was co-evaporated simultaneously with magnesium on the organic layer as a cathode, and a 110 nm MgAg / Ag layer was evaporated to complete the device.
When a voltage was applied to this device, a current density of 1 mA / cm², A luminous efficiency of 1.0 lm / W or more and an external quantum efficiency of 0.8% or more were observed.
[0072]
【The invention's effect】
The thiophene derivatives of the present invention have excellent hole blocking ability as an organic electroluminescent device and have not only sufficient emission luminance even under low voltage driving, but also a vacuum deposited film for forming an electron transport layer or a light emitting layer. An organic electroluminescent device having excellent film-forming properties and being excellent as an electron transporting material or a luminescent material can be obtained.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing one embodiment of the organic electroluminescent device of the present invention.
FIG. 2 is a conceptual diagram showing a second embodiment of the organic electroluminescent device of the present invention.
FIG. 3 is a conceptual diagram showing another embodiment of the organic electroluminescent device of the present invention.
[Explanation of symbols]
1: Transparent substrate
2A: anode
2B: cathode
3: Hole transport layer
4: Light emitting layer
5: electron transport layer
5-1: electron transport layer
5-2: Electron transport layer
6: Light-emitting electron transport layer

Claims (6)

The following general formula (1)

Wherein R ¹ and R ² are the same or different and each represent a hydrogen atom, an alkyl group or an alkoxy group, and R ³ represents a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a heterocyclic group; Ar- is represented by the following formula (2)

(In the formula, R ⁴ represents an alkyl group, and m is an integer of 0 to 3.)
Or the following formula (3)

(In the formula, R ⁵ represents an alkyl group, and n is an integer of 0 to 2.)
Or the following formula (4)

(In the formula, R ⁶ represents an alkyl group, and p is an integer of 0 to 2.)
Or the following formula (5)

(In the formula, R ⁷ represents an alkyl group, and q is an integer of 0 to 2.)
Or the following formula (6)

(In the formula, R ⁸ represents an alkyl group, and r is an integer of 0 to 2.)
Indicates one of ]
Thiophene derivatives represented by the formula: The following general formula (7)

(Wherein, R ¹ and R ² are the same or different and each represents a hydrogen atom, an alkyl group or an alkoxy group, and R ³ represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group). After reacting thiophenes with alkyllithium, the resulting reaction mixture is added to the following general formula (8)
B (OR ⁹ ) ₃
(In the formula, R ⁹ represents an alkyl group.)
And reacting with the addition of a trialkoxyborane represented by the following general formula (9)

(In the formula, R ¹ , R ² , R ³ and R ⁹ are the same as described above.)
To obtain a dialkoxythienylborane represented by the following general formula (10)
X-Ar-X
[Wherein, X represents a halogen atom, and -Ar- represents the following formula (2)

(In the formula, R ⁴ represents an alkyl group, and m is an integer of 0 to 3.)
Or the following formula (3)

(In the formula, R ⁵ represents an alkyl group, and n is an integer of 0 to 2.)
Or the following formula (4)

(In the formula, R ⁶ represents an alkyl group, and p is an integer of 0 to 2.)
Or the following formula (5)

(In the formula, R ⁷ represents an alkyl group, and q is an integer of 0 to 2.)
Or the following formula (6)

(In the formula, R ⁸ represents an alkyl group, and r is an integer of 0 to 2.)
Indicates one of ]
Wherein the compound is reacted with a dihalogen-substituted aryl compound or heterocyclic compound represented by the formula (1) in a solvent in the presence of a palladium catalyst and a base:

(Wherein R ¹ , R ² , R ³ and —Ar— are the same as described above). An organic electroluminescent device comprising an organic layer containing a thiophene derivative represented by the general formula (1) according to claim 1. 2. An organic electroluminescent device comprising a transparent substrate on which an anode, a hole transport layer, an electron transport layer, a light emitting layer, and a cathode are stacked, wherein the electron transport layer is a thiophene derivative represented by the general formula (1) according to claim 1. The organic electroluminescent device according to claim 3, comprising an organic layer containing: The organic electroluminescent device according to claim 4, wherein the light emitting layer contains an iridium complex. The organic electroluminescent device according to claim 4, wherein the thiophene derivative represented by the general formula (1) according to claim 1 is contained in both the electron transport layer and the light emitting layer.

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