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Comparison of CC Triple and Double Bonds as Spacers in Push–Pull Chromophores
Author(s) -
Frank Brian B.,
Laporta Philip R.,
Breiten Benjamin,
Kuzyk Mark C.,
Jarowski Peter D.,
Schweizer W. Bernd,
Seiler Paul,
Biaggio Ivan,
Boudon Corinne,
Gisselbrecht JeanPaul,
Diederich François
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100378
Subject(s) - chemistry , chromophore , intramolecular force , triple bond , homo/lumo , crystallography , molecule , acceptor , double bond , homologous series , bond length , stereochemistry , photochemistry , polymer chemistry , crystal structure , organic chemistry , physics , condensed matter physics
We report the synthesis and properties of two series of homologous donor–acceptor (D–A) chromophores in which N , N ‐dimethylanilino (DMA) or N , N ‐dihexylanilino (DHA) donors and dicyanovinyl acceptors are separated by up to four C≡C triple‐bond spacers or up to three C=C double‐bond spacers. The intramolecular charge‐transfer (CT) interactions of the new D–A oligoynes and the known all‐ trans D–A oligoenes were investigated by X‐ray crystallography, electrochemistry, UV/Vis spectroscopy, and theoretical calculations. In both series, the optical and electrochemical HOMO–LUMO gaps decrease with increasing spacer length. The HOMO–LUMO gaps for the D–A oligoynes and oligoenes with a given spacer length are nearly identical. The effect of the spacer length was found to level‐off for spacers with more than six carbon atoms. The third‐order optical nonlinearity of both series of molecules was determined by measuring the rotational averages of the third‐order polarizabilities γ rot by degenerate four‐wave mixing.