摘要
采用B3LYP/6-310*方法,对1-吡啶-3-[4-(苯基偶氮)苯基]-三氮烯(PYPAPT)各异构体进行优化,同时用ab initio HF单激发组态相互作用(CIS)法在6-31G*基组上优化各异构体最低激发单重态几何结构,并探讨了其分子结构与能量的关系,计算结果表明:(1)所有基态异构体基本保持Cs对称性,各原子基本处在同一平面中,而激发态各异构体分子的共轭性不如基态分子,在激发态分子中与偶氮相连的另一苯环与三氮烯及与其相连的苯和吡啶环都不在一个平面;(2)无论在气相中还是在二氯甲烷(DCM,ε=8.93),乙醇(EtOH,ε=24.55)和乙腈(ACN,ε=36.64)溶剂中,基态时PYPAPT主要以M11存在,激发态时为J11较稳定。运用含时密度泛函理论(TD-DFT)计算了PYPAPT基态和激发态各异构体在溶剂中的吸收与发射光谱,研究了溶剂模型对理论光谱的影响。计算结果表明,PYPAPT各异构体基态和激发态的HOMO和LUMO都是离域π键,随着溶剂极性的增强,HOMO和LUMO轨道能量都逐渐下降。理论电子光谱证实,PYPAPT各异构体的吸收光谱随溶剂极性的增强略微红移,吸收强度也有微弱升高;最大吸收源自于HOMO→LUMO的π→π(?)电子跃迁,最强发射光谱主要来自于具有π→π(?)跃迁特征的局域激发态S_3。
The ground state on the isomerization of 1-pyridine-3-[4-phenylazopheny]-Triazene （PYPAPT） （Mxy（x=l-5,）,y=1-2）） was studied by density functional theory at B3LYP/6-31G＊ level, at the same time, the molecular structure of the first singlet excited state for the isomerization of PYPAPT （jxy（x=l-5, y= 1-2）） and was optimized by CIS/6-31G＊. The energies of their frontier molecular orbitals or relative energies ER and the molecular structures were investigated theoretically. The calculated results show that （1） PYPAPT complexes in the ground state were found to be practically planar and have a Cs symmetry, however, diazoamino, benzene ring,pyridine ring and azobenzol of complexes in the excited state are not in the plane. （2） the M11 structure in the ground state is always dominant both in the gas phase and aqueous solution and the J11 structure in the excited state is the smallest energy. The theoretical electronic spectra and the emission spectra were calculated with PCM-TD-B3LYP/6-31＋G（d） in the dichloromethane （DCM, e=8.93）, ethanol （EtOH, e=24.55）, aeetonitrile （CAN, e=36.64） solution. The influences of solvent model on the electronic absorption spectra and emission spectra were also probed. The calculated results show that delocalized π bonds exist in the isomerization of Mxy and Jxy, as the solvent polarity increases, the energy levels of the highestoccupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） of Mxy and Jxy exhibit a progressively reducing pattern. Theoretical spectra achieved prove that their absorptions are red-shifted and the absorption intensity increased with an increasing the solvent polarity. The maximum aborption peaks of Mxy and emission peakes of d^y complexes originate from π （HOMO）→π＊ （LUMO） transition.
出处
《计算机与应用化学》
CAS
CSCD
北大核心
2011年第9期1179-1184,共6页
Computers and Applied Chemistry
基金
湖南省高校创新平台开放基金项目(09K099)
湖南省科技厅项目(2010JT4041)
湖南省重点学科资助
衡阳市科技局项目(2010KJ27)
关键词
密度泛函理论
含时密度泛函理论
PYPAPT:CIS
光谱
density functional theory, time-dependent density functional theory, PYPAPT, configuration interaction with single excitationmethod
spectra
