A quantum chemical study of the spectral and luminescent properties of the BPA + 2H2O complex was carried out. Calculations were performed by the semi-empirical method of intermediate neglect of differential overlap using a program complex and a special parameterization. The spectral behavior of BPA in water was modeled by a complex with water molecules in the ratio 1: 2 forming the hydrogen bond. The calculated data were compared with the results of investigation of the isolated BPA molecule. The nonplanar BPA structure leads to the strong mixing of the π- and σ-type atomic wave functions. The main reason for the low quantum yield of the BPA fluorescence is the efficient process of singlet-triplet conversion in the S1(ππ*) ≳ Tn(πσ*) channel of the BPA molecule and its complex with water. A study of the photolysis of the isolated BPA molecule upon exposure to solar radiation, the short-wavelength boundary of which on the Earth’s surface is located at ~290 nm (~34480 cm–1), showed that the energy of the photodissociative state localized on the O–H bond is much higher than this value for BPA. The binding curve is characteristic of the S1(ππ*) state, while the singlet and triplet states of the πσ* type, localized on the single C–C bonds of the central fragment of the molecule, are repulsion curves with a barrier. From our point of view, the low efficiency of the BPA degradation under the influence of solar radiation is due to the presence of a significant potential barrier to the photolysis in the singlet or triplet state. The mechanisms of bond breaking in the BPA + 2H2O complex are different for the singlet and triplet states, namely, for the S3(πσ*) state, the break occurs by the predissociation mechanism, and for the Tn(πσ*) state, due to its population through the singlet-triplet conversion in the S1(ππ*) → Тn(πσ*) channel.

中文翻译：

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双酚A在水中的电子光谱和光解

对 BPA + 2H2O 复合物的光谱和发光特性进行了量子化学研究。计算是通过使用复杂程序和特殊参数化的中间忽略微分重叠的半经验方法进行的。BPA 在水中的光谱行为通过与水分子的复合物以 1:2 的比例形成氢键来模拟。将计算数据与分离的 BPA 分子的研究结果进行比较。非平面 BPA 结构导致 π 型和 σ 型原子波函数的强烈混合。BPA 荧光量子产率低的主要原因是 BPA 分子及其与水的复合物的 S1(ππ*) ≳ Tn(πσ*) 通道中单线态-三线态转换的有效过程。对分离的 BPA 分子在暴露于太阳辐射时光解的研究，其在地球表面的短波长边界位于 ~290 nm (~34480 cm-1)，表明光解离态的能量局部化O-H 键上的值远高于 BPA 的这个值。结合曲线是 S1(ππ*) 态的特征，而 πσ* 型的单线态和三线态，位于分子中心片段的单个 C-C 键上，是具有屏障的排斥曲线。从我们的角度来看，BPA 在太阳辐射影响下的降解效率低是由于在单线态或三线态下存在显着的光解势垒。BPA + 2H2O 复合物中的键断裂机制对于单线态和三线态是不同的，