几种B环间位取代异黄酮衍生物的核磁共振谱理论研究(英文)

Theoretical study on nuclear magneticresonance spectra of eight kinds of isoflavone derivatives with meta-substituents on B ring

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。

Eight kinds of isoflavone derivatives with rneta-substituent on B ring have been optimized at B3LYP/6-31G＊＊ level. At B3LYP/6-311 G＊＊ level and by GIAO method, NMR spectra of the title compounds have been studied. The results show that the In- tramolecular hydrogen bonding has been formed in 1E -1H and 2E - 2H compounds whose bond length is about 0.2773nm. NMR spectra characteristics of the compounds with 9-hydroxyl substituting hydrogen have been discussed. The chemical shifts of adjacent carbon and adjacent hydrogen decrease owing to increase of electron cloud density and strengthening of shielding effect. However, the chemical shift of the conjoint carbon has more increase. In addition ,the effects of substituents on the chemical shift have been discussed. The chemical shifts of ortho-and para-hydrogens increase along with strengthening of substituent groups＇supplying electron to benzene. Substituent groups have little effect on hydrogens of A and C rings. The chemical shift of para-carbon increases as sub- stituent groups＇supplying electron to benzene increases. The chemical shift of ortho-carbon hasn＇t a distinet change rule.