Structure-behavior study of a family of "hybrid cyanine" dyes which exhibit inverted solvatochromismElectronic supplementary information (ESI) available: CCDC 1504720-1504724. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6cp06708e

The inverted solvatochromism of twenty dyes containing an electron-donor phenolate conjugated with an electron-withdrawing nitro-substituted phenyl ring was analyzed in terms of the dye structure and substituents. Structural factors that increased the difference between the electrophilicities of the donor and acceptor moieties, or the donor-acceptor strength of the phenolate dyes, also increased the sensitivity of the dyes to solvent-polarity changes and red-shifted their solvatochromic absorption bands. The reverse solvatochromism of twenty "hybrid cyanine" dyes reflects their different responses to some properties of the solvent.