Investigation of the N^C Ligand Effects on Emission Characteristics in a Series of Bis-Metalated [Ir(N^C) 2 (N^N)] + Complexes.

Autor: Hendi Z; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia.; Department of Chemistry, Sharif University of Technology, Tehran P.O. Box 11155-3516, Iran., Kozina DO; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia., Porsev VV; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia., Kisel KS; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia., Shakirova JR; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia., Tunik SP; Institute of Chemistry, Saint-Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russia.
Jazyk: angličtina
Zdroj: Molecules (Basel, Switzerland) [Molecules] 2023 Mar 17; Vol. 28 (6). Date of Electronic Publication: 2023 Mar 17.
DOI: 10.3390/molecules28062740
Abstrakt: A series of bis-metalated phosphorescent [(N^C) 2 Ir(bipyridine)] + complexes with systematic variations in the structure and electronic characteristics of the N^C ligands were synthesized and characterized by using elemental analysis, mass spectrometry, NMR spectroscopy and X-ray crystallography. Investigation of the complexes' spectroscopic properties together with DFT and TD DFT calculations revealed that metal-to-ligand charge transfer (MLCT) and intraligand (LC) transition play key roles in the generation of emissive triplet states. According to the results of theoretical studies, the 3 LC excited state is more accurate to consider as an intraligand charge transfer process (ILCT) between N- and C-coordinated moieties of the N^C chelate. This hypothesis is completely in line with the trends observed in the experimental absorption and emission spectra, which display systematic bathochromic shifts upon insertion of electron-withdrawing substituents into the N-coordinated fragment. An analogous shift is induced by expansion of the aromatic system of the C-coordinated fragment and insertion of polarizable sulfur atoms into the aromatic rings. These experimental and theoretical findings extend the knowledge of the nature of photophysical processes in complexes of this type and provide useful instruments for fine-tuning of their emissive characteristics.
Databáze: MEDLINE
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