Hydrogen bond effect of the photoswitching of a spiropyran dyad

Abstract

A new molecular dyad including a spiropyran and a fluorescein fragment linked by the azomethine spacer was prepared. The chromogenic properties of the molecular dyad are due to the presence of spiropyran moiety showing positive photochromism. The azomethine fragment in the side chain is generally stabilized by an intramolecular hydrogen bond. The existence of two photochromic units allows the control of the chromogenic properties of the molecular dyad through intermolecular H-bond with the solvent. The main conclusions were supported by quantum chemical DFT calculations.