PHOTOINDUCED ELECTRON-TRANSFER IN POLYCHROMOPHORIC SYSTEMS .2. PROTONATION DIRECTED SWITCHING BETWEEN TRICHROMOPHORIC AND BICHROMOPHORIC INTERACTION
PHOTOINDUCED ELECTRON-TRANSFER IN POLYCHROMOPHORIC SYSTEMS .2. PROTONATION DIRECTED SWITCHING BETWEEN TRICHROMOPHORIC AND BICHROMOPHORIC INTERACTION
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DOI：
10.1021/ja00317a028
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发表时间：
1984-01-01
影响因子：
15
通讯作者：
VERHOEVEN, JW
中科院分区：
文献类型：
--
作者：
MES, GF;VANRAMESDONK, HJ;VERHOEVEN, JW
合成了一系列分子D2-D1-A，其中2个电子供体生色团(D_1，三烷基氨基和D_2，取代的苯胺基)和一个电子受体生色团(A，(氰基)萘基)通过一个构象良好的饱和烷基骨架相连，在A和D_1和D_2之间分别保持了2.4和4.7°的最近原子-原子距离。与没有苯胺基供体的双色分子D1-A相比，三色分子的荧光光谱显示出分子内的电荷转移发射，能量明显较低。再加上电荷转移荧光对苯胺基取代基的响应，这意味着在发射激发态，在D2处产生大量的正电荷。双色分子D_1-A在酸性极性介质中选择性质子化后，光致电子转移被有效地抵消。然而，在这些条件下，三色系转变为电子模式，涉及从D2到A的直接长程电子转移。
The synthesis of a series of molecules D2-D1-A is described in which 2 electron donor chromophores (D1, a trialkylamino group, and D2, a (substituted) anilino group) and an electron acceptor chromophore (A, a (cyano)naphthyl group) are linked by a saturated paraffinic skeleton of well-defined conformation, which maintains closest atom-atom distances of 2.4 and 4.7 .ANG. between A and D1, and D2, respectively. The fluorescence spectra of the trichromophoric molecules display an intramolecular charge-transfer emission at significantly lower energy than bichromorphoric molecules D1-A lacking the anilino donor. Together with the response of the charge-transfer fluorescence to substituents in the anilino group, this implies that in the emissive excited state a substantial positive charge develops at D2. Photoinduced electron transfer in bichromophoric molecules D1-A is effectively canceled upon selective protonation of D1 in acidified polar media. Under these conditions, the trichromorphoric systems, however, switch to a mode of electron involving direct long-range electron transfer from D2 to A.