Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.
Department of Chemistry, University of Warsaw, Żwirki i Wigury 101, 02-089, Warsaw, Poland.
Chemistry. 2023 Jun 27;29(36):e202300680. doi: 10.1002/chem.202300680. Epub 2023 May 15.
A synthetic approach to two regioisomeric π-electron extended [1,4]thiaborins annulated with two benzothiophene units has been developed. The central thiaborin rings of the boracycles obtained exhibit different electronic properties; this is reflected in their different aromatic characters, boron Lewis acidity and UV-vis spectroscopic behavior. Thiaborins were converted to boron dipyrromethene (BODIPY) complexes. Their emission spectra exhibit two distinct bands resulting from LE and CT transitions. Strong near-infrared phosphorescence in Zeonex thin films at 77 K indicates efficient intersystem crossing and the formation of triplet states. Separation of HOMO and LUMO orbitals between boracyclic and BODIPY moieties facilitates electron transfer to a CT state followed by a transition to the LE triplet state located on the ligand. These unique properties of spiro thiaborin-BODIPY complexes were explored for their application as singlet-oxygen photosensitizers. They show excellent photocatalytic performance with singlet oxygen quantum yields reaching 77 % and full conversion of the model organic substrate achieved after 1.5 h with only 0.05 % mol catalyst load.
已经开发出了一种将两个苯并噻吩单元环化到两个区域异构的π-电子扩展[1,4]噻硼啉中的合成方法。所得到的硼杂环的中环噻硼啉环表现出不同的电子性质；这反映在它们不同的芳香性质、硼路易斯酸度和紫外可见光谱行为中。噻硼啉被转化为硼二吡咯甲川（BODIPY）配合物。它们的发射光谱表现出两个不同的带，这是由 LE 和 CT 跃迁引起的。在 77 K 的 Zeonex 薄膜中观察到强近红外磷光，表明有效的系间窜越和三重态的形成。硼杂环和 BODIPY 部分之间的 HOMO 和 LUMO 轨道的分离有利于电子向 CT 态转移，然后跃迁到位于配体上的 LE 三重态。这些螺环噻硼啉-BODIPY 配合物的独特性质被探索用于作为单线态氧光敏剂。它们表现出优异的光催化性能，单线态氧量子产率达到 77%，仅用 0.05%mol 的催化剂负载量，在 1.5 h 内即可完全转化模型有机底物。
