Kumar GD, Liao YC, Nazir R, Banasiewicz M, Chou PT, Gryko DT. Strongly emitting, centrosymmetric, ladder-type bis-coumarins with crankshaft architecture.
Phys Chem Chem Phys 2023;
25:28824-28828. [PMID:
37853830 DOI:
10.1039/d3cp04121b]
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Abstract
Quadrupolar bis-coumarins bearing dialkylamino groups, prepared by a double Pechmann reaction and subsequent oxidation, strongly emit yellow-orange light. Comparison with non-substituted analogs reveals that, the photophysical properties of the conjugated bis-coumarins are controlled both by the dialkylamino substituents and by the π-system. Analogous but non-conjugated bis-coumarins emit blue light both in solution and in crystalline state. Unusually fast oxidation process in the crystalline state is responsible for the presence of two bands in their solid-state emission. Two-center, charge-transfer transition from an orbital delocalized on the entire molecule to the central benzene ring is responsible for photophysical properties.
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