Solvation effect and aggregation of semipermanent spiro[indole-phenanthrolinoxazines] in CH3CN / H2O binary solvent

Abstract

For three 5-alkyloxyspiro[indolephenanthrolinoxazines], the open form possesses a low-polarity semi-quinoidal structure. In acetonitrile-water binary solvent, the merocyanine is stabilized by a specific interaction with a water molecule. At high water content, the hydrated open form gives rise to H-aggregates.

Diverse Self-Assembly in Soluble Oligoazaacenes: A Microscopy Study

“…The fluorescence spectrum of compound 3 in solution shows a maximum at 595 nm although in the solid state the fluorescence is completely quenched. These changes are consistent with the formation of π−π stacked aggregates possibly having an antiparallel dipole arrangement …”

“…Electronic spectroscopy reveals a small red shift in both absorption and emission in the solid state (Figure c), perhaps suggesting increasing interchromophore interactions but not indicating any specific intermolecular interactions. In the case of 3 , complete quenching of its fluorescence in the solid state leads us to propose a π−π stacking aggregation mode . This is supported to some extent by the increase in intensity of its electronic absorption bands at shorter wavelength in its solid-state UV/vis spectrum (Figure c), whereas fiberlike aggregates would be expected from such a mode as a result of the bundling of linear molecular stacks.…”