Luminescence properties and spatial arrangement of lignin model molecules in the solid - II. Crystal structures of 2,2 '-dibenzyloxy-5,5 '-di(1-hydroxyethyl)3,3 '-dimethoxybiphenyl and 2,2 '-dibenzyloxy-5,5 '-dihydroxymethyl-3,3 '-dimethoxybiphenyl and their fluorescence emission

The X-ray structures of two benzyl alcohol type biphenyl lignin model molec ules 3 and 4 were determined and their fluorescence properties established in the crystalline state and in heptane and methanol solutions at 300 K. No phosphorescence emission was observed at 77 K in contrast to the conjugate d carbonyl biphenyl compounds 1 and 2, The torsion angle in the biphenyl fl uorophore appeared to be the main parameter governing the fluorescence emis sion in the solid and liquid states. (C) 1999 Elsevier Science B.V. All rig hts reserved.