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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The Optical Spectra of NiP, NiPz, NiTBP, and NiPc: Electronic Effects of Meso-tetraaza Substiution and Tetrabenzo Annulation
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The Optical Spectra of NiP, NiPz, NiTBP, and NiPc: Electronic Effects of Meso-tetraaza Substiution and Tetrabenzo Annulation

机译：NiP，NiPz，NiTBP和NiPc的光谱：中四方氮取代和四苄基环的电子效应

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摘要

Time-dependent density functional calculations have been performed on the symmetry and spin-allowed Eu excited states of the nickel tetrapyrrole series, NiP, NiPz, NiTEP, and NiPc. Optical spectra collected in noncoordinating solvents are presented for NiTEI>, for the newly synthesized octaethyl nickel porphyrazine, NiOEPz, and for MgOEPz. The theoretical results prove to agree very well with the experimental data, providing an accurate description of the UV -vis spectra. The effects on the optical spectra of introducing in the basic porphyrinic ring, aza bridges, benzo rings, both aza bridges and benzo rings, and a transition metal are highlighted and interpreted on the basis of the electronic structure changes occurring along the series. The following results were found: (i) The near-degeneracy of the configurations (alueg) and (a2ueg) of the four- orbital model leads to strong mixing in NiP. The resulting low-energy state corresponds to the Q band with low intensity due to opposing transition dipoles of the contributing transitions. In NiTEP, NiPz, and NiPc, the degeneracy is lifted, and the lowest transition becomes increasingly purely (atueg) with concomitant larger intensities in the Q band, which is most intense in NiPc. (ii) The E band is calculated to correspond in NiP to a strong mixture of the degenerate (alueg) and (a2ueg) configurations with parallel transition dipoles, hence a large intensity. In NiPz and NiPc, the E band can no longer be described in terms of the four-orbital model, it has considerable MLCT character in NiPz and corresponds to a more complicated configuration mixing in NiPc. (iii) Transitions involving metal 3d states, either MLCT or LMCT, influence notably the spectrum to ~ the blue of the E band.
机译：对四吡咯镍系列，NiP，NiPz，NiTEP和NiPc的对称性和自旋允许的Eu激发态进行了随时间变化的密度泛函计算。给出了在非配位溶剂中收集的光谱，用于NiTEI>，新合成的八乙基镍卟啉NiOEPz和MgOEPz。理论结果证明与实验数据非常吻合，可提供对UV-vis光谱的准确描述。基于沿着该系列发生的电子结构变化，突出并解释了引入基本的卟啉环，氮杂桥，苯并环，氮杂桥和苯并环以及过渡金属对光谱的影响。发现以下结果：（i）四轨道模型的构型（alueg）和（a2ueg）接近简并导致NiP中的强烈混合。由于贡献跃迁的相反跃迁偶极子，所产生的低能态对应于具有低强度的Q波段。在NiTEP，NiPz和NiPc中，简并性提高了，最低的跃迁变得越来越纯净（atueg），同时在Q带中强度也变大，而在QP中强度最大。 （ii）计算出的E带在NiP中对应于简并（alueg）和（a2ueg）构型与平行跃迁偶极子的强混合物，因此强度大。在NiPz和NiPc中，不能再用四轨道模型来描述E带，它在NiPz中具有相当大的MLCT特性，并且对应于NiPc中更复杂的构型混合。 （iii）涉及金属3d态的跃迁，无论是MLCT还是LMCT，都会显着影响E波段蓝色的光谱。

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