2,4-二硫代尿嘧啶的紫外吸收光谱和共振拉曼光谱

发布时间：2018-08-05 13:44

【摘要】：硫代嘧啶碱基是光动力疗法潜在的重要光敏剂,其最低单重激发态的光物理研究已有广泛报道。然而,其较高激发态的跃迁性质和反应动力学研究较为稀少。因此,本文采用共振拉曼光谱和密度泛函理论计算方法研究2,4-二硫代尿嘧啶的紫外光谱和几个较高单重激发态的短时结构动力学。首先,基于共振拉曼光谱强度与电子吸收带振子强度f的关系,将紫外光谱去卷积成四个吸收带,分别为358 nm(f=0.0336)中等强度吸收带(A带),338 nm(f=0.1491)、301 nm(f=0.1795)和278 nm(f=0.3532)强而宽的吸收带(B、C和D带)。这一结果既吻合密度泛函理论计算结果,又符合共振拉曼光谱强度模式对紫外光谱带的预期。据此,去卷积得到的四个吸收带被分别指认为S0→S2跃迁、S0→S6跃迁、S0→S7跃迁和S_0→S_8跃迁。同时,分别对B,C和D带共振拉曼光谱进行了详细的指认,获得了短时动力学信息。结果表明,S_8态短时动力学的显著特征是在Franck-Condon区域或附近发生了S8(ππ~*)/S(nπ~*)势能面交叉引发的、伴随超快结构扭转的非绝热过程。S7和S6态短时动力学的主要特征是反应坐标的多维性,它们分别沿C_5C_6/C_2S_8/C_4S_(10)/N_2C_3+C_4N_3H_9/N_1C_2N_3/C_2N_1C_6/C_6N_1H_7/C_5C_6H_(12)和C_5C_6/N_3C_2/C_4S_(10)/C_2S_8+C_6N_1H_7/C_5C_6H_(12)/C_5C_6N_1/C_5C_6H_(12)/C_2N_1C_6/N_1C_2N_3/C_4N_3H_9/N_1C_2N_3等内坐标演化。
[Abstract]:Thiouracil bases are potential important Guang Min agents for photodynamic therapy, and the photophysical studies of their lowest single excited states have been widely reported. However, there are few studies on the transition properties and reaction kinetics of the higher excited states. In this paper, resonance Raman spectroscopy and density functional theory are used to study the UV spectra of 2O4-dithiouracil and the short-time structural kinetics of several higher singlet excited states. Firstly, based on the relationship between the resonance Raman spectrum intensity and the intensity f of the electron absorption band, the UV spectrum is deconvolution into four absorption bands, which are 358 nm (f0. 0336) medium intensity absorption band (A band), 338 nm (ft0. 1491), 301 nm (fU 0. 1795) and 278 nm (f0. 3532) strong and wide absorption bands (BU C and D bands). The results not only agree with the results of density functional theory, but also accord with the expectation of the intensity mode of the resonance Raman spectrum for the ultraviolet band. On this basis, the four absorption bands obtained by deconvolution are identified as S0 / S2 transition, S0 / S6 transition, S0 / S7 transition and S0 / S-1 / S8 transition respectively. At the same time, the resonance Raman spectra of BFC and D bands were identified in detail, and the short time kinetic information was obtained. The results show that the short term dynamics of S 8 states is characterized by the cross initiation of S 8 (蟺 O *) / S (n 蟺 O *) potential energy surfaces in or near the Franck-Condon region. The main feature of the short term dynamics of S 8 states is the multidimension of the reaction coordinates in the non adiabatic process S7 and S 6 states with the torsion of ultrafast structures. 瀹冧滑鍒嗗埆娌緾_5C_6/C_2S_8/C_4S_(10)/N_2C_3 C_4N_3H_9/N_1C_2N_3/C_2N_1C_6/C_6N_1H_7/C_5C_6H_(12)鍜孋_5C_6/N_3C_2/C_4S_(10)/C_2S_8 C_6N_1H_7/C_5C_6H_(12)/C_5C_6N_1/C_5C_6H_(12)/C_2N_1C_6/N_1C_2N_3/C_4N_3H_9/N_1C_2N_3绛夊唴鍧愭爣婕斿寲.
【作者单位】：浙江理工大学化学系;
【基金】：国家自然科学基金(21473163) 国家重点基础研究发展规划项目(973)(2013CB834607)资助~~
【分类号】：O626.41;O657.3

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