Investigation of Three Diasteromeric Chalcone Epoxides Derivatives by NMR Spectroscopy and X-ray Crystallography

Abstract

Structures of diasteromeric chalcone epoxides derivatives [3-(4-nitrophenyl)oxiran-2-yl)(phenyl)]-methanone (C15H11NO4), compound 1; (3,4-dimethoxy phenyl)-(3-(4-nitrophenyl)-oxiran-2-yl)methanone (C17H15NO6) compound 2 and [(3-(4-nitrophenyl)-oxiran-2-yl) phenyl-methanol] (C15H13NO4) compound 3 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the monoclinic space group P21/c with unit cell parameters a = 10.3127(10), b = 10.45331(10), c = 12.9227(13) A, β = 113.769(2)°, Z = 4. Compound 2 crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.977(1), b = 8.259(1), c = 13.964(2) A, α = 103.889(2), β = 91.151(2), γ = 100.780(2)°, Z = 2. Compound 3 crystallizes in the monoclinic space group P21 with unit cell parameters a = 6.708(1), b = 8.388(1), c = 12.407(2) A, β = 103.322(3)°, Z = 2. The absolute configurations of 3 for the chiral centers are 1S, 2R, and 3R. In structures 1 and 2, the molecules in the crystal are linked by C–H···O interactions and van der Waals forces. Molecules 2 in the crystal are stacked in an anti-parallel fashion along the a-axis by π···π interactions which gives additional support to molecular packing stability. In structure 3, the molecules in the crystal are linked by both intra- and intermolecular hydrogen bonds O1–H···O2 and O1–H···O4, respectively. Adjacent molecules are interconnected by intermolecular weak C–H···O interactions. Structures of three diasteromeric chalcone epoxides derivatives [3-(4-nitrophenyl)oxiran-2-yl)(phenyl)]-methanone 1; (3,4-dimethoxyphenyl)-(3-(4-nitrophenyl)-oxiran-2-yl)methanone 2 and [(3-(4-nitro phenyl)-oxiran-2-yl) phenyl-methanol] 3 were established by spectral and X-ray diffraction studies. The geometric parameters of the oxirane ring are in good agreement with those found in the literature and exist as trans isomer. The crystal packing in all three structures is stabilized by weak intermolecular C–H···O interactions. In structure 3, the molecules in the crystal are internally stabilized by both intra- and intermolecular O–H···O hydrogen bonds.