SYNTHESES AND PHOTO-FUNCTIONALITY DESIGN OF UNSYMMETRICALLY SUBSTITUTED BIPYRIDINES

有机荧光颜料因其在各个领域的潜在应用前景而引起了人们的广泛关注。本课题重点研究具有不对称取代基的2,2′-联吡啶结构的新型有机荧光颜料。初步结果表明，6,6′-二氨基-2,2′-联吡啶（dabp）具有较强的荧光。合成了一系列氨基和氯取代联吡啶，发现在溶液和固体中，6个氨基取代基是强蓝色荧光所必需的。其中，不对称取代的6-氨基-6′-氯-2,2′-联吡啶（acbp）的发光最强（phi=0.8）， Stokes位移大（约90 nm），在三层EL器件中制备dabp和acbp时，电致发光较弱。在每个吡啶单元上都有供电子和吸电子取代基的acbp荧光最强，Stokes位移大，推测激发态下两个吡啶单元之间的分子内电荷转移可能起作用。在此基础上，合成了具有大Stokes位移的扭曲分子内电荷转移（TICT）发射的新型芳香酰胺型宿主分子，并表明通过调节TICT发射可以直接监测具有三氢键的尿嘧啶衍生物的分子识别。在质子溶剂中长波长侧观察到的dabp弱发射归因于亚胺互变异构体。在此基础上，合成了dabp的烷基衍生物，该衍生物通过多重氢键相互作用识别脂肪酸，并通过酰胺-亚胺互变异构改变其发射来监测相互作用。

Organic fluorescent pigment has been attracting considerable interest because of its potential application in variety of fields. In this project, we focused on developing new organic fluorescent pigment that has the 2,2'-bipyridine structure with unsymmetrical substituent(s). Preliminary results revealed that 6,6'-diamino-2,2'-bipyridine(dabp) showed strong fluorescence. A series of amino and chloro substituted bipyridines was synthesized, and it was found that 6-amino substituent was essential for strong blue fluorescence in solution and in solid. Among them, unsymmetrically substituted 6-amino-6'-chloro-2,2'-bipyridine(acbp) showed strongest emission (phi=0.8) with large Stokes shift(ca 90 nm), and weak electroluminescence was observed when dabp and acbp were fabricated in three layr-type EL device.As acbp that has electron-donating and electron-withdrawing substituents on each pyridine unit showed strongest fluorescence with a large Stokes shift, possible role of intramolecular charge transfer between the two pyridine units at excited state was suggested. On the basis of these results, new aromatic amide-type host molecule that showed a twisted intramolecular charge transfer(TICT) emission with a large Stokes shift was synthesized, and it was shown that molecular recognition of the uracil derivatives with triple hydrogen bonding was directly monitored by modulation of the TICT emission.Weak emission of dabp observed in protonic solvent at longer wavelength side was ascribed to the imide tautomer. Based on this observation, alkyl derivatives of dabp were synthesized, and the derivative demonstrated the ability to recognize fatty acids by multiple hydrogen bonding interaction and to monitor the interaction by alteration of its emission due to the amide-imide tautomerization.