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在B3LYP/6-31G**水平下优化了几种B环间位取代异黄酮衍生物的几何构型,在B3LYP/6-311G**水平下计算了该类化合物的核磁共振谱。研究结果表明:在1E!1H和2E～2H中的分子内氢键,其键长为0.1668nm,使整个分子形成一个四环的交叉共轭体系。从9位羟基取代对异黄酮衍生物NMR数据的影响来看,相邻的碳和相邻的氢化学位移的减少是由于电子云密度的增加和屏蔽作用的加强。而相邻碳的化学位移增加更大。此外,从取代基对化学位移的影响进行了讨论。邻对位氢的化学位移与取代基使苯环电子云密度增大的趋势相一致。A环和C环上的氢基本不受取代基的影响。对位碳的化学位移则与取代基使苯环电子云密度增大的趋势相反,邻位碳的化学位移变化趋势不明显。
At B3LYP / 6-31G ** level, the geometries of several isocyclic substituted isoflavone derivatives of B ring were optimized. The NMR spectra of these compounds were calculated at the B3LYP / 6-311G ** level. The results show that the intramolecular hydrogen bond in 1E! 1H and 2E ~ 2H has a bond length of 0.1668 nm, which makes the entire molecule form a four-ring cross-conjugated system. From the effect of hydroxyl substitution at position 9 on NMR data of isoflavone derivatives, the reduction of chemical shifts of adjacent carbons and adjacent hydrogens is due to an increase in electron cloud density and enhancement of the shielding effect. While the chemical shifts of adjacent carbons increase even more. In addition, the effects of substituents on chemical shifts are discussed. The chemical shifts of ortho-para-hydrogen coincide with the tendency of substituents to increase the density of benzene ring electron clouds. Hydrogen on ring A and ring C is essentially free of substituents. The chemical shift of para carbon is opposite to the tendency of substituents to increase the electron density of benzene ring. The chemical shift of adjacent carbon is not obvious.