Szłapa-Kula Agata, Palion-Gazda Joanna, Ledwon Przemyslaw, Erfurt Karol, Machura Barbara
Institute of Chemistry, Faculty of Science and Technology, University of Silesia in Katowice, Szkolna 9, Poland.
Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice, Poland.
Dalton Trans. 2022 Oct 4;51(38):14466-14481. doi: 10.1039/d2dt02439j.
A series of Re(I) carbonyl complexes with the 1-imidazo[4,5-][1,10]phenanthroline (imphen) ligand functionalized with electron-donating amine groups attached to the imidazole ring phenylene linkages were designed to investigate the impact of remote amine substituents on the ground- and excited-state properties of [ReCl(CO)(R-CH-imphen)]. The complexes [ReCl(CO)(R-CH-imphen)] belong to the family of [ReCl(CO)(diimine)] systems, but contrary to strongly related phenanthroline Re(I) carbonyl complexes with a rich history in coordination chemistry, they are really sparse. The effects of electron-rich N-donor groups in [ReCl(CO)(R-CH-imphen)] were fully studied with the use of cyclic voltammetry, absorbance and emission spectroscopy, and transient absorption spectroscopy, and they were simulated by density functional theory. The attachment of electron-rich amine groups to CH-imphen resulted in a decrease in oxidation potentials and a noticeable bathochromic shift of the longest absorption wavelength of [ReCl(CO)(R-CH-imphen)] compared with the parent compound [ReCl(CO)(CH-imphen)] due to a significant destabilization of the HOMO energy level. Regarding the excited-state properties, the triplet emission red-shift of [ReCl(CO)(R-CH-imphen)] induced by appended electron-rich N-donor groups was accompanied by a significant increase in excited state lifetimes, up to a 12-fold enhancement compared with the parent chromophore. The lifetime prolongation of [ReCl(CO)(R-CH-imphen)] bearing amine substituents was rationalized by the population of the ligand-localized triplet state, while the solvent-dependent photoluminescence characteristics of [ReCl(CO)(R-CH-imphen)] were correlated with strong hydrogen bonding interactions between the acidic imidazole NH proton and highly polar solvents. The present findings are of high importance for understanding and controlling the excited-state nature of transition metal complexes.
设计了一系列含有1-咪唑并[4,5 - ][1,10]菲咯啉（imphen）配体的铼（I）羰基配合物，该配体通过连接在咪唑环亚苯基键上的供电子胺基进行功能化，以研究远程胺取代基对[ReCl(CO)(R-CH-imphen)]基态和激发态性质的影响。配合物[ReCl(CO)(R-CH-imphen)]属于[ReCl(CO)(二亚胺)]体系，但与在配位化学方面有着丰富历史的密切相关的菲咯啉铼（I）羰基配合物不同，它们的研究非常少。通过循环伏安法、吸收光谱和发射光谱以及瞬态吸收光谱对[ReCl(CO)(R-CH-imphen)]中富电子氮供体基团的影响进行了全面研究，并通过密度泛函理论进行了模拟。与母体化合物[ReCl(CO)(CH-imphen)]相比，富电子胺基连接到CH-imphen上导致氧化电位降低，并且[ReCl(CO)(R-CH-imphen)]最长吸收波长出现明显的红移，这是由于最高占据分子轨道（HOMO）能级的显著不稳定。关于激发态性质，由附加的富电子氮供体基团引起的[ReCl(CO)(R-CH-imphen)]的三重态发射红移伴随着激发态寿命的显著增加，与母体发色团相比增强了12倍。带有胺取代基的[ReCl(CO)(R-CH-imphen)]的寿命延长是由配体局部三重态的占据来解释的，而[ReCl(CO)(R-CH-imphen)]的溶剂依赖性光致发光特性与酸性咪唑NH质子和高极性溶剂之间的强氢键相互作用相关。本研究结果对于理解和控制过渡金属配合物的激发态性质具有重要意义。
