LUMINESCENCE PROPERTIES AND SPATIAL ARRANGEMENT OF LIGNIN MODEL MOLECULES IN THE SOLID .1. CRYSTAL STRUCTURES OF 5,5'-DIACETYL-2,2'-DIBENZYLOXY-3,3'-DIMETHOXYBIPHENYL AND 2,2'-DIBENZYLOXY-5,5'-DIFORMYL-3,3'-DIMETHOXYBIPHENYL AND THEIR PHOSPHORESCENCE

摘要

The X-ray structures of two alpha-carbonyl biphenyl lignin model molecules (1 and 2) were determined and their luminescence properties established in the crystalline state and in methylcyclohexane solutions at 300 and 77 K. The spatial arrangement in the solid of both compounds was found to be very similar; it explains the similarity of the phosphorescence spectra of the crystals at 77 K. In contrast, the phosphorescence emission of the solutions (approximate to 10(-5) mol l(-1)) at 77 K revealed differences attributed to electronic and conformational effects which perturb the interactions between the biphenyl and benzyl moieties. No detectable fluorescence emission was detected for both compounds at 300 K in methylcyclohexane and in the crystalline state. (C) 1997 Elsevier Science B.V. [References: 26]