采用DFT/B3LYP方法对3种母环氨基修饰的罗丹明类衍生物的结构进行了全优化,得到此3种化合物的基态和激发态的结构参数、振动光谱、前线分子轨道能量等相关数据,并在基态和激发态几何构型优化的基础上,用TD-DFT方法计算了其气相吸收光谱及发射光谱,全面分析了结构特征对热稳定性、前线分子轨道及光谱性质的影响。结果表明:化合物a末端氨基的扭转运动程度最低,化合物b相对于化合物a,分子共轭及平面程度提高,末端氨基的扭转运动程度增大,气相最大吸收波长及最大发射波长红移,且计算分子中最大发射波长最长,热稳定性最低。化合物c在计算分子中共轭及平面程度、热稳定性、HOMO能量最高,能隙最低,气相最大吸收波长最长。但相对于化合物b末端氨基的扭转运动程度增大,最大发射波长蓝移。
The structures of three rhodamine derivatives were optimized by means of DFT/B3LYP method, and the data of the structural parameters and thermodynamic parameters of the excited state and ground state of the three rhodamine derivatives and their vibrational spectra and frontier molecular orbital energy level were obtained. On the basis of fully optimized structures of excited state and ground state, their gas absorption and emission spectra were studied by time-dependent density functional theory (TD-DFT), while the effects of their structural features on thermal stability, frontier molecular orbital and spectra properties were fully analyzed. The results indicate that the compound a has the lowest reverse movement degree of terminal amino among these molecules, and in contrast, the compound b was better conjugated and planar, the reverse movement degree of terminal amino improved, the gas absorption and emission spectra were red shifted, and it has the longest maximum emission wavelength and the lowest thermal stability among these molecules. The compound c was best conjugated and planar, its thermal stability and energy of HOMO were the highest, its HOMO-LUMO gap was most narrow, and it has the longest maximum absorption wavelength. It was found that the reverse movement degree of terminal amino of compound c improved compared to b, so its maximum emission wavelength was blue shifted.