Dual fluorescence of 2-(4′-N,N-dimethylaminophenyl)pyrido[3,4-d]imidazole: effect of solvents
Dual fluorescence of 2-(4′-N,N-dimethylaminophenyl)pyrido[3,4-d]imidazole: effect of solvents
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2-(4′-N,N-二甲基氨基苯基)吡啶并[3,4-d]咪唑的双荧光：溶剂的影响
DOI：
10.1016/s1386-1425(99)00059-1
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
S. Dogra
中科院分区：
文献类型：
--
作者：
G. Krishnamoorthy;S. Dogra
研究了2-(4‘-N，N-二甲氨基苯基)吡啶并[3，4-d]咪唑(DMAPPI)在不同溶剂中的光谱特性。在极性/非质子性和极性/质子性溶剂中观察到双重荧光。短波长(SW)发射带被指定为局部激发(B*)态，而长波长(LW)发射带是由于扭曲的分子内电荷转移(TICT，A*)态。在Sw和LW发射处记录的荧光激发光谱表明，这两个发射都来自相同的基态物种。时间相关的荧光研究表明，在激发态下这些发射之间不存在平衡。TICT态对B*态的反向反应比B*态对A*态的正向反应慢得多。对分离和溶剂化的DMAPPI分子进行了AM1计算。这些研究表明，氢键使吡哆咪唑(PI)环与苯环更加平坦，这有利于电荷从N，N-二甲氨基苯基(DMAP)环流向电子吸引基(PI)。
Spectral characteristics of 2-(4′-N,N-dimethylaminophenyl)pyrido[3,4-d]imidazole (DMAPPI) have been studied in different solvents. Dual fluorescence is observed in polar/aprotic and polar/protic solvents. Short wavelength (SW) emission band is assigned to the locally excited (B*) state, whereas the long wavelength (LW) emission band is due to the twisted intramolecular charge transfer (TICT, A*) state. Fluorescence excitation spectra recorded at SW and LW emissions suggest that both these emission originate from the same ground state species. Time correlated fluorescence studies have suggested that there is no equilibrium between these emissions in the excited state. The reverse reaction of TICT state to the B* state is much slower than the forward reaction of B* state to A* state. AM1 calculations were carried out on the isolated and solvated DMAPPI molecules. These studies have shown that the hydrogen bonding made the pyridoimidazole (PI) ring more planar with benzene ring and this facilitates the flow of charge from the N,N-dimethylaminophenyl (DMAP) ring to the electron withdrawing group (PI).