Synthesis, structures, and phototransformations of 3-acyl-2-hetarylchromones with nitroxide substituents
摘要
Methods were developed for the synthesis of hybrid products responsive to both UV irradiation and magnetic stimuli. 2-Furyl-3-acylchromones containing paramagnetic groups (piperidine-N-oxyl and 2-imidazoline-3-oxide-1-oxyl) in the acyl and furanyl moieties of the molecules were prepared. The molecular and crystal structure of the paramagnetic derivative containing the 2-imidazoline-3-oxide-1-oxyl substituent was determined by X-ray diffraction. Short intermolecular contacts between the oxygen and C(2) atoms of the nitronyl nitroxide moieties, at which the spin density of opposite signs is accumulated, were revealed. It was demonstrated that UV irradiation of chromone, containing a paramagnetic moiety isolated from the conjugated benzopyran system, leads to its rearrangement giving a fluorescent product.