Synthesis, Crystal Structure and Thermal Property of Dimethyl Phenanthrene-9,10-dicarboxylate

The target compound (C18H14O4) was synthesized and structurally determined by single-crystal X-ray diffraction. The crystal is of monoclinic system, space group P2(1)/n with a = 7.9383(6), b = 19.5083(13), c = 9.4189(7) angstrom, beta = 98.981(2)degrees, C18H14O4, M-r = 294.29, D-c = 1.357 g/cm(3), V = 1440.75(18) angstrom(3), Z = 4, F(000) = 616, mu(MoKa) = 0.096 mm(-1), T = 293(2) K, 3320 independent reflections with 1845 observed ones (I > 2 sigma(I)), R = 0.0529 and wR = 0.1082 with GOF = 1.015 (R = 0.1202 and wR = 0.1278 for all data). The phenanthrene skeleton is coplanar. The overall crystal packing revealed that it has reverse staggered parallel and stratified arrangement. And a one-dimensional interaction model was formed by two kinds of pi-pi interactions between the two adjacent molecules at upper and lower levels. The decomposition mechanism of compound 3 is complex.