Papamichalis Eleftherios, Petsalakis Ioannis D, Tzeli Demeter
Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens 157 84, Greece.
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, Athens 116 35, Greece.
J Phys Chem A. 2025 Jul 10;129(27):5942-5952. doi: 10.1021/acs.jpca.5c02035. Epub 2025 Jun 25.
Porphyrins are detected in many biological systems and have significant roles in some important artificial systems, while the N-confused porphyrins present very interesting photophysical and chemical properties, which differ from those observed in porphyrins. In the present study, metal (M) complexes of tetraphenylporphyrin (TPP), N-confused TPP (NCTPP), and the ethenyl-pyrazine derivative of NCTPP (NCTPP-p), i.e., M-TPP, M-NCTPP, and M-NCTPP-p, where M = Zn and Ni, were studied via density functional theory (DFT) and TD-DFT calculations. The photophysical properties of molecules and their absorption spectra are studied. It has been found that the M affects the relative stability of the M-NCTPP and M-NCTPP-p tautomers, resulting in different tautomers having the lowest energy structure, while for the M-NCTPP-p molecule, there are cis isomers, which are lower in energy than the corresponding trans isomers due to the van der Waals interactions. The global minima of the nickel complexes have the H atom of a reversed pyrrole attached to C (), while the zinc complexes have the H atom outside of the porphyrin core attached to N (). For M-NCTPP-p, the global minimums are (Ni) and (Zn). The absorption main peaks of M-NCTPP-p are red-shifted compared to M-NCTPP up to 80(135) nm for the Soret(Q) bands. The different isomers present shifts of their main absorption peaks up to 50(180) nm. Additionally, the vertical de-excitation energies from selected excited states are also investigated. Overall, the selection of the metal and the peripheral group lead to different lowest values in the energy structure, affect its UV-vis absorption spectrum, and thus they tune the photophysical properties of the M-NCTPP complexes.
卟啉在许多生物体系中都能被检测到，并且在一些重要的人工体系中发挥着重要作用，而N-杂卟啉具有非常有趣的光物理和化学性质，与卟啉中观察到的性质不同。在本研究中，通过密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）计算研究了四苯基卟啉（TPP）、N-杂四苯基卟啉（NCTPP）以及NCTPP的乙烯基吡嗪衍生物（NCTPP-p）的金属（M）配合物，即M-TPP、M-NCTPP和M-NCTPP-p，其中M = Zn和Ni。研究了分子的光物理性质及其吸收光谱。研究发现，M影响M-NCTPP和M-NCTPP-p互变异构体的相对稳定性，导致不同的互变异构体具有能量最低的结构，而对于M-NCTPP-p分子，存在顺式异构体，由于范德华相互作用，其能量低于相应的反式异构体。镍配合物的全局最小值中，反转吡咯的H原子连接在C（）上，而锌配合物中，卟啉核外的H原子连接在N（）上。对于M-NCTPP-p，全局最小值分别为（Ni）和（Zn）。与M-NCTPP相比，M-NCTPP-p吸收主峰的Soret（Q）带红移高达80（135）nm。不同异构体的主要吸收峰位移高达50（180）nm。此外，还研究了选定激发态的垂直去激发能。总体而言，金属和外围基团的选择导致能量结构中出现不同的最低值，影响其紫外可见吸收光谱，从而调节了M-NCTPP配合物的光物理性质。
