In order to ascertain the effect of ring strain on the electronic spectra of cyclic acetylenes, a series of p,p′-bridged cyclic tolans (Vn, n=11, 12, 13, 14, and 18) has been synthesized. It was found that the increasing ring strain exerted an appreciable hypochromic effect and also caused a slight bathochromic shift of the absorption band. The bathochromic shift observed in the p,p′-bridged cyclic tolans (Vn) forms a contrast with the hypsochromic shift observed in the strained o,o′-bridged cyclic diphenyldiacetylene (VI, n=3).
为了确定环张力对环状
炔烃电子光谱的影响,合成了一系列p,p′-桥接的环状托烯(Vn,n=11、12、13、14和18)。结果发现,增加的环张力产生了显著的淡色效应,并导致了吸收带的轻微红移。在p,p′-桥接的环状托烯(Vn)中观察到的红移与在受张力的o,o′-桥接环状二苯二炔(VI,n=3)中观察到的蓝移形成了对比。