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Cross-Conjugated Systems Based On An (E)‑Hexa-3-en-1,5-diyne-3,4-diyl Skeleton: Spectroscopic and Spectroelectrochemical Investigations

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posted on 20.11.2015, 00:00 by Josef B. G. Gluyas, Valentina Manici, Simon Gückel, Kevin B. Vincent, Dmitry S. Yufit, Judith A. K. Howard, Brian W. Skelton, Andrew Beeby, Martin Kaupp, Paul J. Low
A series of cross-conjugated compounds based on an (E)-4,4′-(hexa-3-en-1,5-diyne-3,4-diyl)­bis­(N,N-bis­(4-methoxyphenyl)­aniline) skeleton (16) have been synthesized. The linear optical absorption properties can be tuned by modification of the substituents at the 1 and 5 positions of the hexa-3-en-1,5-diynyl backbone (1: Si­(CH­(CH3)2)3, 2: C6H4CCSi­(CH3)3, 3: C6H4COOCH3, 4: C6H4CF3, 5: C6H4CN, 6: C6H4CCC5H4N), although attempts to introduce electron-donating (C6H4CH3, C6H4OCH3, C6H4Si­(CH3)3) substituents at these positions were hampered by the ensuing decreased stability of the compounds. Spectroelectrochemical investigations of selected examples, supported by DFT-based computational studies, have shown that one- and two-electron oxidation of the 1,2-bis­(triarylamine)­ethene fragment also results in electronic changes to the perpendicular π-system in the hexa-3-en-1,5-diynyl branch of the molecule. These properties suggest that (E)-hexa-3-en-1,5-diynyl-based compounds could have applications in molecular sensing and molecular electronics.