摘要
采用密度泛函理论(DFT)方法,在B3LYP/6-31G*水平上对乙烯基噻吩共轭螺噁嗪化合物SO-SO3的几何构型、电子结构、前线分子轨道等进行了理论研究,计算结果表明:SO-SO3的开环过程会使得开环体的左右两个部分键长均等化,导致共轭体系变大,能隙明显减小;乙烯基噻吩基团共轭接入螺噁嗪母体后,导致体系的共轭作用变大,在激发态下电子流动增强,形成由乙烯基噻吩向萘并噁嗪的有效电荷转移与能量转移;结合前线分子轨道成分分析乙烯基噻吩单元在最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)中的轨道贡献率明显增加.含时密度泛函理论(TD-DFT)计算的电子吸收光谱结果显示:当接入的乙烯基噻吩单元达到2-3个时,影响SO2和SO3开环的最低能量激发态变为第一激发单重态S1,并且均源自电子从HOMO至LUMO的跃迁且为π-π*跃迁;其最大吸收波长λmax达到466-540nm,且红移十分明显,其对应开环体O-SO2与O-SO3的λmax达到605和647nm.
We carried out a theoretical study on the geometries, electronic structures, and frontier molecular orbitals of vinyl thiophene group conjugated spirooxazines （SO-SO3） using density functional theory （DFT） at the B3LYP/6-31G＊ level. The calculated results show that the equalization of bond lengths at the left and right parts of the open-forms occurred during the ring-opening process. A large conjugated system was formed and this significantly narrowed the energy gap. The conjugated system became larger and its electrons flowed easily because of the introduction of different lengths of vinyl thiophene conjugation moieties into the spirooxazine molecule. The electrons and energy efficiently transferred from the vinyl thiophene to naphthoxazine. The orbital contribution rate of the vinyl thiophene group in the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） increased obviously. Time-dependent DFT （TD-DFT） calculations showed that as the conjugated vinyl thiophene unit reached 2-3 the first singlet excited state of SO2 and SO3 resulted from the electron transition from the HOMO to the LUMO, which were also assigned to the π-π transition. Meanwhile,λmax was between 466 and 540 nm with an obvious red-shift while the λmax of O-SO2 and 0-SO3 reached 605 and 647 nm, respectively.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2011年第8期1847-1853,共7页
Acta Physico-Chimica Sinica
基金
国家高技术研究发展计划(0099AA03500)
上海市重点学科(B502)
上海市重点实验室(08DZ2230500,09JC1404300)资助项目~~
关键词
乙烯基噻吩
螺噁嗪
密度泛函理论
前线分子轨道
电子吸收光谱
Vinyl thiophene
Spirooxazine
Density functionaltheory
Frontier molecular orbitaElectronic absorption spectrum
