Rodrigues Ana Clara B, Lopes Susana M M, Cunha Carla, Braz João, Pinho E Melo Teresa M V D, Seixas de Melo J Sérgio, Pineiro Marta
University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10263-10277. doi: 10.1039/d2cp05941j.
A comprehensive study on the electronic spectral, photophysical and acid-base properties of phenyl- and methyl-oxime corrole derivatives and of triphenylcorrole (model corrole) has been performed, aiming to shed light on the existing species in the ground and excited states. Solvents and corrole concentration are found to govern the properties of the studied compounds and are determinants of their applicability in studies. In THF, the neutral corrole has two tautomeric forms (T1 and T2). In DMSO, the deprotonated form shows a characteristic long-wavelength Q band slightly shifted to blue when compared with the T1 tautomer and a higher fluorescence quantum yield. In ACN, with the increase of the corrole concentration formation of an aggregate due to homoconjugation (with dimer characteristics) is observed, and pioneeringly reported using UV-Vis and fluorescence studies and confirmed by carrying out titrations with TFA. The effect of the oxime group on the p values of a corrole is found to influence the formation of a homoconjugate, namely by precluding its formation (at higher concentrations) when compared with the model corrole. TDDFT electronic quantum calculations support the experimental observations, namely the existence of tautomers and deprotonated species, with their respective electronic spectral features, further allowed proposing a structure for the homoconjugate complex in ACN. The characteristics of the oxime-corroles, namely a p of ∼ 5, absorption and emission at 650 nm and solvent dependent properties, make them good candidates for their use in biological systems either as probes, sensors, or as new sensitizers for photodynamic therapy.
对苯基肟和甲基肟卟啉衍生物以及三苯基卟啉（模型卟啉）的电子光谱、光物理和酸碱性质进行了全面研究，旨在阐明基态和激发态中存在的物种。发现溶剂和卟啉浓度决定了所研究化合物的性质，并且是其在研究中适用性的决定因素。在四氢呋喃中，中性卟啉有两种互变异构形式（T1和T2）。在二甲基亚砜中，去质子化形式显示出特征性的长波长Q带，与T1互变异构体相比略微向蓝色移动，并且荧光量子产率更高。在乙腈中，随着卟啉浓度的增加，观察到由于同共轭作用（具有二聚体特征）形成聚集体，首次通过紫外可见光谱和荧光研究报道，并通过用三氟乙酸进行滴定得到证实。发现肟基对卟啉p值的影响会影响同共轭物的形成，即与模型卟啉相比，在较高浓度下会阻止其形成。含时密度泛函理论电子量子计算支持了实验观察结果，即互变异构体和去质子化物种的存在及其各自的电子光谱特征，进一步有助于提出乙腈中同共轭复合物的结构。肟基卟啉的特性，即p值约为5、在650nm处有吸收和发射以及溶剂依赖性性质，使其成为在生物系统中用作探针、传感器或作为光动力疗法新敏化剂的良好候选物。
