Key Laboratory of Analytical Science for Food Safety and Biology (Ministry of Education and Fujian Province), State Key Laboratory of Photocatalysis on Energy and Environment, Department of Chemistry, Fuzhou University, Fuzhou, 350116, PR China.
Key Laboratory of Analytical Science for Food Safety and Biology (Ministry of Education and Fujian Province), State Key Laboratory of Photocatalysis on Energy and Environment, Department of Chemistry, Fuzhou University, Fuzhou, 350116, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Dec 15;263:120167. doi: 10.1016/j.saa.2021.120167. Epub 2021 Jul 10.
In this work, six iridium(III) complexes have been designed, synthesized and characterized. The molecular structures of complex 1 ([(pba)Ir(bpy-2N(CH))]PF), 2 ([(pba)Ir(bpy-2NH)]PF) and 3 ([(pba)Ir(bpy-2CH)]PF) were determined by single crystal X-ray diffraction. Upon addition of Hcy (homocysteine) to the solution of complex 1, a luminescent variation from orange red to green was observed by the naked eye, corresponding to a large blue shift from 604 nm to 498 nm (~106 nm). While the emission intensity of complex 1 was almost no change after addition of other common amino acids including Cys (cysteine) and GSH (glutathione). The aldehyde group of complex 1 formed a new thiazinane/thiazolidine ring with Hcy/Cys confirmed by H NMR and high-resolution mass spectrometry. And the new product 1-Hcy had a higher quantum yield than 1-Cys. Theoretical calculations showed that the HOMO (highest occupied molecular orbital) of 1-Hcy was located on the newly formed six-membered thiazinane ring, which was different from the HOMO of 1-Cys. Compared with the other iridium(III) complexes, we can speculate that the large blue shift and enhancement of the emission intensity of the complex 1 were related to the strong electron donating ability of the modified amino groups on bipyridine ligand. This will provide an idea for the design of ratio-based luminescence probes for Hcy in future.
在这项工作中，设计、合成并表征了六个铱（III）配合物。配合物 1([(pba)Ir(bpy-2N(CH))]PF)、2([(pba)Ir(bpy-2NH)]PF)和 3([(pba)Ir(bpy-2CH)]PF)的分子结构通过单晶 X 射线衍射确定。当向配合物 1 的溶液中加入 Hcy（同型半胱氨酸）时，通过肉眼观察到从橙红色到绿色的发光变化，对应于从 604nm 到 498nm（约 106nm）的大蓝移。而配合物 1 的发射强度在加入其他常见氨基酸（包括 Cys（半胱氨酸）和 GSH（谷胱甘肽））后几乎没有变化。配合物 1 的醛基与 Hcy/Cys 形成了新的噻嗪/噻唑啉环，这通过 1H NMR 和高分辨率质谱得到证实。并且新产物 1-Hcy 的量子产率高于 1-Cys。理论计算表明，1-Hcy 的 HOMO（最高占据分子轨道）位于新形成的六元噻嗪环上，这与 1-Cys 的 HOMO 不同。与其他铱（III）配合物相比，我们可以推测配合物 1 的大蓝移和发射强度增强与吡啶配体上修饰的氨基的强供电子能力有关。这将为未来设计基于比率的 Hcy 荧光探针提供思路。
