Chemistry of naphthazarin derivatives 13. Conformational analysis of 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones by quantum chemistry methods
作者:V. P. Glazunov、D. V. Berdyshev、A. Ya. Yakubovskaya、N. D. Pokhilo
DOI:10.1007/s11172-006-0480-z
日期:2006.10
The molecular structures of various conformers of 2-hydroxy-1,4-naphthoquinone; 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones; 2,5,8-trihydroxy-1,4-naphthoquinone; and 3-(alk-1-enyl)-2,5,8-trihydroxy-1,4-naphthoquinones were studied by density functional theory (B3LYP/6-31(d), B3LYP/6-31(d, p)) and ab initio (MP2/6-31G, MP2/6-31(d)) methods. The strengths of the intramolecular hydrogen bonds formed by the β-hydroxy group with the O atom at C(1) and with the double bond π-electrons of the alkenyl substituents in the quinonoid rings were estimated. The compounds studied mainly exist as rotamers with the former-type hydrogen bonds. The splitting of the quinonoid bands of the stretching vibrations of the β-hydroxy group in the IR spectra of 3-(alk-1-enyl)-2-hydroxy-1,4-naphthoquinones and 3-(alk-1-enyl)-2,5,8-trihydroxy-1,4-naphthoquinones in hexane solutions is due to the existence of rotamers formed upon internal rotation of the alkenyl substituent.
通过密度泛函理论 (B3LYP/6-31(d), B3LYP/6-31(d, p)) 和从头算 (MP2/6-31G, MP2/6-31(d)) 方法研究了2-羟基-1,4-萘醌、3-(链烯-1-基)-2-羟基-1,4-萘醌、2,5,8-三羟基-1,4-萘醌和3-(链烯-1-基)-2,5,8-三羟基-1,4-萘醌的各种构象分子的分子结构。估算了β-羟基与C(1)位氧原子及与醌环上链烯基取代基双键π电子形成的分子内氢键的强度。所研究的化合物主要以形成前一种类型氢键的旋转异构体形式存在。3-(链烯-1-基)-2-羟基-1,4-萘醌和3-(链烯-1-基)-2,5,8-三羟基-1,4-萘醌在己烷溶液中的红外光谱中β-羟基伸缩振动的醌带分裂是由于链烯基取代基内旋转形成的旋转异构体存在所致。