玫红酸钡分子结构及荧光光谱的PM7半经验分子轨道法研究

Study on molecular structure and fluorescence spectra of barium rhodizonate precipitate by PM7 method

以mopac2013量化计算软件包中PM7量子化学半经验分子轨道方法计算了玫红酸钡相关分子的热力学参数和分子轨道及其能量。利用热力学原理分析获得的数据表明,玫红酸与氯化钡生成玫红酸钡和玫红酸钡交叉二聚体都能自发生成,交叉二聚体是其中更稳定形态。对获得的前线分子轨道及其能量分析表明,只有交叉二聚体具有较大荧光光谱,属于二光子激发过程,与实验结果一致。此结果为常用有色沉淀剂玫红酸二钠在荧光分析钡等金属离子的应用提供理论依据。

In order to explain and understand the unusual experimental fluorenseent spectrum of barium rhodizonate complex in aqueous solution theoretically, we build up the hydraded molecular cluster models of barium rhodizonate complex by ACDFreel2 sol, ware, and calculate the molecular structural parameters and frontier molecular orbitals and its energies of barium rhodizonate precipitate related molecular clusters models by PM7 of semi-empirical molecular orbital method of quantum chemistry using MOPAC2013 software package. The analysis of the obtained thermodynamic parameters shows the formations of barium rhodizonate and cross mixed dimmer of barium rhodizonate were both stable and spontaneously formed, the later one is more stable. The frontier orbital analysis indicated that the cross mixed dimmer of barium rhodizonate may give out fluorescence spectrrum, which belongs to two-photo excitation process and is accord with the experimental results. The calculation results help us understand the unusual fluorescent spectrum well, and it may offers a good evidence for disodium rhodizonate of a color precipitant for Barium and other metal ions being used as a useful fluorescent reagent.