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On Excited States of Alkyl Bridged [14] Annulenes
Author(s) -
SpangetLarsen Jens,
Gleiter Rolf
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610825
Subject(s) - chemistry , excited state , annulene , cndo/2 , dichroic glass , singlet state , anthracene , alkyl , atomic physics , molecular physics , photochemistry , stereochemistry , molecule , physics , optoelectronics , organic chemistry
The linear dichroic absorption spectrum of 1,3,6,8‐trans‐15, 16‐hexamethyl‐dihydropyrene has been measured in stretched polyethylene at 77K, and CNDO‐CI calculations with inclusion of singly and doubly excited configurations have been carried out on a series of alkyl bridged [14] annulenes with pyrene‐ and anthracene‐shaped perimeters. Transitions to e 3g → e 4u type 1 B states are well described, and the results indicate that additional low‐energy excited states originate from e 3g → e 5g and e 2u → e 4u type configurations interacting strongly with doubly excited configurations of the e 3g , e 3g → e 4u , e 4u type. The second excited singlet state responsible for the weak transition observed between the 1 L bands may be assigned to one of these additional states, but it is probably of complex nature, similar to the ‘phantom’ state in linear polyenes.