Monitoring structural transformations in crystals. Part 4. Monitoring structural changes in crystals of pyridine analogs of chalcone during [2+2]-photodimerization and possibilities of the reaction in hydroxy derivatives

We studied the [2 + 2]-photodimerization in crystals of pyridine analogs and hydroxy derivatives of chalcone using the X-ray structure analysis. The mutual orientation of adjacent molecules in the crystals was analyzed in a quantitative way and the results were compared with data for known photoactive crystals undergoing the [2 + 2]-photodimerization. In the case of one pyridine analog, we processed the single-crystal-to-single-crystal photodimerization and determined the structure for the mixed crystal containing both the substrate and the product. We also explained a role of hydrogen bonds in the [2 + 2]-photodimerization in the case of the hydroxy derivatives of chalcone. C5H4N-CO-CH = CH-C6H5: a = 6.0885(7) Angstrom, b = 13.1022(14) Angstrom c = 13.7197(17)Angstrom, beta = 91.318(10)degrees, Tonoclinic, P2(1)/n, Z = 4. The irradiated crystal of the above analog: a = 6.1502(7) Angstrom, b = 12.9740(13)Angstrom, c = 13.7964(15) Angstrom, beta = 91.870(10)degrees, monoclinic, P2(1)/n, Z = 4. C6H5-CO-CH = CH-C5H4N: a = 23.907(6) Angstrom, b = 4.6709(10) Angstrom, c = 21.199(6) Angstrom, beta = 110.01 (3)degrees, monoclinic, C2/c, Z = 8. C6H5-CO-CH = CH-C6H4(o-OH): a = 13.295(6) Angstrom, b = 5.659(2) Angstrom, c = 16.144(8) Angstrom, beta = 109.73(5)degrees, monoclinic, P2(1)/n Z = 4. C6H5-CO-CH = CH-C6H4(p-OH): a = 5.3446(7) Angstrom, b = 12.9304(18) Angstrom, c 17.134(2) Angstrom, orthorhombic, P2(1)2(1)2(1), Z = 4. (C) 2003 Elsevier Inc. All rights reserved.