4,4′-[1,n-亚烷基双[(E)-2-(4-氧苯基)乙烯基]]双吡啶的光化学性质

通过E-[4-[2-(4-羟基苯基)乙烯基]吡啶与1,n-二溴烷烃亲核取代反应合成了4,4′-[1,n-亚烷基双[(E)-2-(4-氧苯基)乙烯基]]双吡啶[n=2(Ia),3(Ib),4(Ic),6(Id)].用元素分析、红外、紫外和质子核磁共振谱鉴定了Ia～Id的结构.将Ia～Id的稀溶液用中压汞灯和低压汞灯交替照射,发现其分子内光环加成反应的存在,并且随着亚烷基碳链的延长,反应速度加快.研究还发现锌离子可以与吡啶环上氮原子发生螯合作用使分子内光环加成反应加快.本文化合物荧光很弱,在较高浓度下有较强分子间激基缔合物荧光.

Photochemical Properties of 4,4′ -[1,n-alkanediylbis[(E)-2-(4-oxyphenyl) ethenyl]]bispyridine

4,4′ -[1,n-alkanediylbis[(E)-2-(4-oxyphenyl)ethenyl]]bispyridine [n=2(Ia),3(Ib),4(Ic),6(Id)] were synthesized by the nucleophilic substitution of (E)-4-[2-(4-hydroxyphenyl)ethenyl]pyridine with 1,n-dibromoalkane.The structures of Ia～ Id were identified by elemental analysis,IR,UV and 1H NMR.The dilute solution of Ia～ Id was irradiated alternatively by medium pressure mercury lamp and low pressure mercury lamp.The intramolecular photocycloaddition was observed and this reaction speeds up with the extension of the alkanediyl chain.It was also found that the photocycloaddition was increased in the presence of zinc cation because of its chelation with the nitrogen atom of the pyridine group.The fluorescence of these compounds is weak and the intermolecular excimer fluorescence is detected at higher concentration.