摘要
通过硝酸铁和水杨酸甲酯的硝基化反应,合成了3-硝基水杨酸甲酯和5-硝基水杨酸甲酯.并用红外光谱、核磁共振光谱、紫外-可见吸收光谱和荧光光谱对产物进行了表征.用量子化学计算结果对其红外光谱、核磁共振光谱、紫外-可见吸收光谱和荧光光谱的性质差异进行了解释.B3LYP/6-31G**和自然价键轨道方法计算结果表明,由于3-硝基水杨酸甲酯具有更强的分子内氢键,其羟基和羰基的红外吸收比5-硝基水杨酸甲酯的红移了,酚羟基的氢谱移向了高位移,紫外吸收产生了增色效应.基于CIS/6-31G**方法,计算了水杨酸甲酯和3-硝基水杨酸甲酯基态和激发态下的分子内质子转移的势能曲线,由势能曲线进一步得到它们的Stokes位移分别为8.4×103和8.9×103cm-1.所有结果表明,由于分子内氢键强弱不同,导致水杨酸甲酯、3-硝基水杨酸甲酯和5-硝基水杨酸甲酯的光谱性质不一样.
Methyl 3-nitrosalicylate (3-MNS) and methyl 5-nitrosalicylate (5-MNS) were synthesized by a nitration reaction between methyl salicylate (MS) and iron (Ⅲ) nitrate under reflux. 3-MNS and 5-MNS were characterized by infrared spectra (IR), proton nuclear magnetic resonance spectra QH-NMR), electronic absorption spectra (UV-Vis), and photoluminescence (PL). The structures of 3-MNS and 5-MNS were fully optimized at the B3LYP/6-31G^** level. The optimized results and nature bond orbital (NBO) analysis results were used to illustrate the red-shift of the O-H and C=O stretching vibrations in the IR, the lower field shift of the phenol hydroxyl proton chemical shift in ^1H-NMR, and the bathochromic shift in the UV-Vis spectra of 3-MNS. Potential energy surfaces for the intramolecular proton transfer of ground (GSIPT) and excited (ESIPT) states of MS and 3-MNS were obtained and the Stokes-shift values for MS and 3-MNS were computed to be 8.4 ×10^3 and 8.9×10^3 cm^-1 using CIS/6-31G^**, respectively. All these results demonstrate that differences in intramolecular hydrogen bonding in MS, 3-MNS, and 5-MNS give rise to large differences in their spectral properties.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2009年第10期2118-2122,共5页
Acta Physico-Chimica Sinica
基金
supported by the Program for Innovative Research Team of Nanchang University, China
Open Foundation of CAS Key Laboratory ofOrganic Solid of China
the Natural Science Foundation of Education Department of Jiangxi Province, China
the Foundation of TrainingAcademic and Technical Header for Main Majors of Jiangxi Province, China~~