4-羟甲基吡啶－水红移氢键的密度泛函理论研究

使用密度泛函理论B3LYP方法和6-311++G**基函数对4-羟甲基吡啶与水形成的1:1和1:2（摩尔比）氢键复合物进行了理论计算研究,分别得到稳定的4-羟甲基吡啶－H₂O和4-羟甲基吡啶－(H₂O)₂氢键复合物3个和8个。经基组重叠误差和零点振动能校正后,最稳定的1:1和1:2氢键复合物的相互作用能分别为-20.536和-44.246 kJ/mol。振动分析显示O-H···N(O)氢键的形成使复合物中O-H键对称伸缩振动频率红移(减小)。自然键轨道分析表明,4-羟甲基吡啶与水形成最稳定的1:1和1:2氢键复合物时,分子间电荷转移分别为0.02642 e 和0.03813 e 。含时密度泛函理论TD-B3LYP/ 6-311++G**计算显示,相对于4-羟甲基吡啶单体分子,氢键H-OH···N和H-OH···OH的形成分别使最大吸收光谱波长兰移8~16纳米和红移4~11纳米。

Density Functional Theory Study of Red‐shifted Hydrogen Bonds of 4‐Pyridinemethanol with Water

The hydrogen bonds of 1:1 and 1:2 complexes formed between 4‐pyridinemethanol and water have been investigated using a density functional theory (DFT) method and 6‐311++G?? ?? basis set, and three and eight stable geometries have been obtained for 1:1 and 1:2 complexes, respectively. The interaction energy is ?20.536 and ?44.256 kJ/mol for the most stable 1:1 and 1:2 complexes, respectively, after the basis set superposition error and zero‐point corrections. The formation of O? H···N(O) hydrogen bonds makes O? H symmetric stretching modes in the complexes red‐shifted relative to those of the monomer. The natural bond orbit analysis indicates that the intermolecular charge transfer between 4‐pyridinemethanol and water is 0.02642 e and 0.03813 e for the most stable 1:1 and 1:2 complexes, respectively. In addition, TD‐B3LYP/6‐311++G?? ?? calculations show that formation of water‐OH···N and water‐OH···OH hydrogen bonds makes maximum absorbance wavelength λ_max blue‐shifted 8–16 nm and red‐shifted 4–11 nm compared to that of 4‐pyridinemethanol monomer molecule, respectively.