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Solvatochromism of π-Extended Pyridinium-Thienylene-Phenolates
Matías Vidal1, Simone Morales1, Raúl Mera-Adasme2
1Facultad de Química y Biología Universidad de Santiago de Chile, Av. Bernardo O'Higgins 3363, Santiago 9170022, Chile.
Abstract:
The synthesis and solvatochromic behavior of two series of pyridinium-thienylene-phenolates, which differ in the relative orientation and length of their donor/acceptor pairs, are reported. Increasing the donor/acceptor distance significantly influences the spectral behavior of the dyes, transforming the negative solvatochromism exhibited by the shorter analogs into a highly symmetrical inverted solvatochromic response when the π-system is increased. Through the application of multiparametric analysis, 1H NMR spectroscopy, and density functional theory (DFT) calculations, it was determined that the transition from negative to inverted solvatochromism is the result of an enhanced sensitivity of the π-extended dyes to solvent polarizability, with the 2,4-thienylene ring present in the bridge playing a crucial role.
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