有机紫外半导体PMTC的制备及理论计算研究

进行了有机紫外半导体N-5-甲基-1,3,4-噻二唑-2-取代]二硫代氨基甲酸钾(PMTC)的制备及FT-IR、Raman、UV-Vis及PL光谱实验表征。对实验测试FT-IR及Raman光谱的振动峰进行了归属,Raman光谱测试发现S-K在152 cm-1有v(S-K-S)伸缩振动。UV-Vis实验光谱表明PMTC在200～350nm波段有紫外吸收,PL实验光谱表明PMTC在340～400 nm波段有明显的紫外发光峰,峰值波长为373 nm,PL谱相对于吸收光谱有Stokes频移。采用密度泛函理论(DFT)方法对PMTC进行了B3LYP/6-31G水平上的分子结构优化、UV-Vis光谱、分子前线轨道、分子电子密度、Mulliken电荷等理论计算。理论研究结果表明:PMTC在UV-Vis波段有三个电子跃迁吸收。前线轨道计算表明PMTC的HOMO的电子主要分布在与K原子相连的两个S原子上,而LUMO轨道的电子主要集中在K原子上,PMTC吸收光子后,产生电子由HOMO至LUMO跃迁的实质是电子由配体(主要是配位S原子)向金属原子K的转移。

The Study of Preparation and Theoretical Calculation on Organic UV Semiconductor PMTC

Organic UV semiconductor Potassium (5-methyl-1,3,4-thiadiazol-2-yl) carbamodithioate (PMTC) has been prepared and experimentally characterized by FT-IR, Raman, UV-Vis and PL spectra. The vibrational peaks in FT-IR and Raman experimental spectra have been assigned. Raman spectrum shows that S-K has a stretching vibration v(S-K-S) at 152.3cm-1. The experimental UV-Vis spectrum indicates that PMTC has an UV absorption in 200-350nm range, the experimental PL shows an obvious UV emission peak in 340-400 range centered at 373nm, the Stokes shift has been observed. The geometry optimization, UV-Vis spectrum, frontier molecular orbitals, electron density as well as Mulliken charges calculations on PMTC have been carried out by using Density Functional Theory (DFT) at B3LYP/6-31G level. Theoretical research results show that PMTC has three electron transition absorptions in UV-Vis band. The frontier molecular orbital calculation on PMTC indicates that for HOMO, electron mainly locates at S atoms which bonded with K atom, as for LUMO, electron mainly locates at K atom. When PMTC absorbs photon, the essence of electron transition from HOMO to LUMO is the electron transfer from ligand(mainly is coordination S atom) to metal atom K.