Specific Structural Features and Photochemical Properties of Three Benzo-Annulated 2,2-Diphenyl[2H]chromenes

The crystal structures of 3,3-diphenylbenzo[f]chromene, C₂₅H₁₈O, 1,3,3-triphenylbenzo[f]chromene, C₃₁H₂₂O, and 2,2-diphenylbenzofuro[2,3-g]chromene, C₂₇H₁₈O₂, have been determined. Annulated 2,2-diphenylchromenes are of interest because of the influence of steric strain energy in the pyran ring on the photochromic properties of these compounds.

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