GROUND-STATE DIMERS IN EXCIMER-FORMING BICHROMOPHORIC MOLECULES .1. BIS(PYRENYLCARBOXY)ALKANES

被引:103
作者
REYNDERS, P [1 ]
KUHNLE, W [1 ]
ZACHARIASSE, KA [1 ]
机构
[1] MAX PLANCK INST BIOPHYS CHEM,SPEKTROSKOPIE ABT,POSTFACH 2841,AM FASSBERG,W-3400 GOTTINGEN,GERMANY
关键词
D O I
10.1021/ja00166a032
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
1H NMR spectra of the l,n-bis(l-pyrenylcarboxy)alkanes (lPC(n)lPC) and 1,n-bis(2-pyrenylcarboxy)alkanes (2PC(n)2PC) with n= 1-16, 22, and 32 were measured in chloroform-d at room temperature. From the changes in chemical shift of the aromatic protons in 2PC(n)2PC, as compared to the hexyl ester of 2-pyrenecarboxylic acid, it is concluded that an intramolecular ground-state dimer is present for n = 3-16, 22, and 32, a sandwich dimer for n > 8, and a shifted symmetric dimer for n = 3-8. With lPC(n)lPC, dimer formation is found for n = 3-16: predominantly an asymmetric dimer, next to a symmetric one (especially for n = 3-7). The solvent dependence of the dimer formation (2PC(5)2PC) can be correlated with the Hildebrand solubility parameter. Variation of temperature has practically no influence (1PC(5)1PC). The conclusions based on the NMR data are confirmed by time-resolved excimer fluorescence measurements. In the case of 2PC(3)2PC, the presence of a ground-state dimer is seen from the dependence of its fluorescence spectrum on the excitation wavelength. In the series of 1PC(n)1PC and 2PC(n)2PC as well as with the dipyrenylalkanes lPy(n)lPy and 2Py(n)2Py mutual through-bond interactions of the aromatic end groups are detected up ton = 8. © 1990, American Chemical Society. All rights reserved.
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页码:3929 / 3939
页数:11
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