密度泛函研究荧光染料对氟离子的识别机理

Density Functional Theory Study on Recognition Mechanism of Fluorescent Dyes for Fluoride

硝基取代的苯基蒽咪哒唑二酮分子PADH可很好地识别氟离子并呈现比率荧光变化.本文运用密度泛函理论研究了染料分子PADH的识别机理.基态和激发态几何优化显示在氢键形成的位置基态和激发态结构参数变化明显;光谱计算和轨道分析得出氟离子复合物PAD-HF的HOMO和LUMO轨道能隙介于PADH和阴离子PAD^-之间;势能曲线计算可知,染料PAD-HF随着N—H键长的增长,PAD-HF有着极低的跨越能垒.以上结果解释了染料分子PADH识别氟离子机理以及比率荧光现象.

Nitro substituted p hibit ratiometric fluorescence henyl anthra imidazole dione molecule （PADH） can well identify fluorine ions and ex- changes. The recognition mechanism of PADH is studied by density functional theory method. The geometry optimizations of the ground state and the excited state reveal the structural parameters of ground state and excited state change obviously at the position of hydrogen bond formation. Spectral analysis and or- bital analysis show that the energy gap between the HOMO and LUMO of PAD-HF is between that of PADH and an- ion PAD-. The excited state potential energy curves show that PAD-HF has very low rotational energy barrier with the increase of the bond length of N--H. The above theoretical results explain the recognition mechanism of fluores- cent dyes for fluoride and the ratio of fluorescence.