13667-11-3Relevant articles and documents
Phenylvinylogously Extended Triphenylmethylium Systems
Hellwinkel, Dieter,Fritsch, Helmut
, p. 2351 - 2360 (2007/10/02)
As isoconjugated models for (phenylazo)tritylium ions of type A the tritylium systems containing one to three styryl or phenylethynyl substituents have been investigated.In accordance with simple theoretical model considerations these ions have VIS absorptions at considerably longer wavelengths than tritylium ion itself.They also show the expected bathochromic band shifts in going from the singly branched (1, 4) to the doubly and triply branched systems 2, 3 and 5, 6 as well as the predicted bathochromic shifts for 4-methoxystyryl (1b-3b) and hypsochromic shifts for 4-( dimethylammoniostyryl)- and 4-(nitrostyryl)tritylium ions 1c-3c and 1d, respectively.For most of the newly prepared tritylium systems fully resolved NMR spectra were obtained, whose signal positions correlate very well with the charge distributions derived from the elementary conjugation model.For the 4,4'-(1,2-ethenediyl)bistritylium system 12, whose color resembles that of 4-styryltritylium ion 1a, only the resonance lines of the inner protons 3,β-H and carbons C-4,β show significant deviations from the corresponding signal positions of the reference systems 1a and tritylium (13). - Key Words: Chromophores, combined / Ethene, diphenyl- / Ethyne, diphenyl- / Phenylmethylium
