On the origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) aqueous solutions. A combined theoretical and experimental study.
On the origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) aqueous solutions. A combined theoretical and experimental study.
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DOI：
10.1016/j.saa.2014.03.022
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发表时间：
2014-08
期刊：
影响因子：
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通讯作者：
E. Wolcan
中科院分区：
文献类型：
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作者：
E. Wolcan
采用6-311++G(d，p)和LanL2TZ(F)基组，用B3LYP和PBE0混合泛函方法研究了蝶呤与Re(CO)3(Pterin)(H2O)络合物的吸收光谱随pH变化的来源。对所研究化合物的电子跃迁涉及的主要分子轨道进行了自然键分析。蝶呤的低能带被描述为H-→-L电子跃迁，可解释为π→π*，n→π*和n→n电子跃迁的混合物，涉及π(C2-N1，C6-N5，C9-C10)和n(C2)轨道，以及LUMO的π*(C6-N5，C7-N8)和n(C4)轨道。Re(CO)3(Pterin)(H2O)的低能带可以描述为不同MLLCT跃迁的组合，其中位于不同π轨道上的电子密度和孤对Re转移到了Pterin部分。除了MLLCT跃迁外，IL、LLCT和LLMCT跃迁对Re(I)配合物在高能带对应的波长区域的吸收也有贡献。用理论计算结果模拟了蝶呤和Re(CO)3(Pterin)(H2O)的酸碱形式的电子光谱，并与实验吸收光谱进行了比较，在吸收带的位置和相对强度上都有很高的精度。
The origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) complex as a function of pH is studied using the hybrid functional B3LYP and PBE0 in combination with 6-311++G(d,p) and LanL2TZ(f) basis sets. A natural bond analysis was performed to the principal molecular orbitals involved in the electronic transitions of the studied compounds. The low energy band of pterin, which is described as a H → L electronic transition, can be interpreted as an admixture ofπ→π*,n→π*andn→nelectronic transitions involvingπ(C2–N1, C6–N5, C9–C10) andn(C2) orbitals of the HOMO andπ*(C6–N5, C7–N8) andn(C4) orbitals of the LUMO. The low energy band of Re(CO)3(pterin)(H2O) can be described as a combination of different MLLCT transitions where electron density residing on differentπorbitals of carbonyl-Re bonds and lone pairs of Re is transferred to pterin moiety. Besides MLLCT transitions, IL, LLCT and LLMCT transitions contribute the absorptions of the Re(I) complex in the wavelength region corresponding to the high energy bands. The calculated electronic spectra of the acid and base forms of pterin and Re(CO)3(pterin)(H2O) were simulated from the theoretical results and compared to the experimental absorption spectra with great accuracy both in position and relative intensities of the absorption bands.