Preiß Julia, Herrmann-Westendorf Felix, Ngo Thien H, Martínez Todd, Dietzek Benjamin, Hill Jonathan P, Ariga Katsuhiko, Kruk Mikalai M, Maes Wouter, Presselt Martin
Institute of Physical Chemistry, Friedrich Schiller University Jena , Helmholtzweg 4, 07743 Jena, Germany.
Leibniz Institute of Photonic Technology (IPHT) , Albert-Einstein-Str. 9, 07745 Jena, Germany.
J Phys Chem A. 2017 Nov 16;121(45):8614-8624. doi: 10.1021/acs.jpca.7b08910. Epub 2017 Nov 8.
Corroles are emerging as an important class of macrocycles with numerous applications because of their peculiar photophysical and metal chelating properties. meso-Pyrimidinylcorroles are easily deprotonated in certain solvents, which changes their absorption and emission spectra as well as their accessible supramolecular structures. To enable control over the formation of supramolecular structures, the dominant corrole species, i.e., the deprotonated form or one of the two NH-tautomers, needs to be identified. Therefore, we focus in the present article on the determination of the UV-vis spectroscopic properties of the free-base NH-tautomers and the deprotonated form of a new amphiphilic meso-pyrimidinylcorrole that can assemble to supramolecular structures at heterointerfaces as utilized in the Langmuir-Blodgett and liquid-liquid interface precipitation techniques. After quantification of the polarities of the free-base NH-tautomers and the deprotonated form by means of quantum chemically derived electrostatic potential distributions at the corroles' van der Waals surfaces, the preferential stabilization of (some of) the considered species in solvents of different polarity is identified by means of absorption spectroscopy. For the solutions with complex mixtures of species, we applied fluorescence excitation spectroscopy to estimate the relative weights of the individual corrole species. This technique might also be applied to identify dominating species in molecularly thin films directly on the subphase' surface of Langmuir-Blodgett troughs. Supported by quantum chemical calculations we were able to differentiate between the spectral signatures of the individual NH-tautomers by means of fluorescence excitation spectroscopy.
由于具有独特的光物理和金属螯合特性，咕啉正成为一类具有众多应用的重要大环化合物。中位嘧啶基咕啉在某些溶剂中很容易去质子化，这会改变它们的吸收和发射光谱以及可及的超分子结构。为了能够控制超分子结构的形成，需要确定主要的咕啉物种，即去质子化形式或两种NH-互变异构体之一。因此，在本文中，我们重点研究了一种新型两亲性中位嘧啶基咕啉的游离碱NH-互变异构体和去质子化形式的紫外-可见光谱性质的测定，该咕啉可以在异质界面组装成超分子结构，如在朗缪尔-布洛杰特和液-液界面沉淀技术中所使用的那样。通过量子化学推导的咕啉范德华表面的静电势分布对游离碱NH-互变异构体和去质子化形式的极性进行量化后，通过吸收光谱确定了（部分）所考虑的物种在不同极性溶剂中的优先稳定性。对于具有复杂物种混合物的溶液，我们应用荧光激发光谱来估计各个咕啉物种的相对含量。该技术也可用于直接识别朗缪尔-布洛杰特槽亚相表面上分子薄膜中的主要物种。在量子化学计算的支持下，我们能够通过荧光激发光谱区分各个NH-互变异构体的光谱特征。
