Effect of the type of linkage between phenyl groups on the structure and photochemical properties of 2,2-diaryl-substituted pyridoannelated [2H]-chromenes
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Three 2,2-diaryl-substituted pyridoannelated [2H]-chromenes have been studied by X-ray diffraction analysis. Bonding of the benzene rings through bridges of different nature and with different length affects substantially the orientation of the benzene rings, steric interactions at the C center, the conformation of the molecule, and the C−O bond length. A correlation between the photocolorability of chromenes under study and the orientation of the benzene rings with respect to the C−O bond, which provides different prerequisites to stabilization of the C(1)-centered, cation formed upon cleavage of the C−O bond, was established. The effect of the orientation of the benzene rings on the dark reaction of ring closure was found.
Key wordschromenes X-ray diffraction analysis photochemistry in solutions structure-property relationship
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