TY - JOUR

T1 - Investigation of the N^C Ligand Effects on Emission Characteristics in a Series of Bis-Metalated [Ir(N^C) 2(N^N)] + Complexes.

AU - Hendi, Zohreh

AU - Kozina, Daria O.

AU - Porsev , Vitaly V.

AU - Kisel , Kristina S.

AU - Shakirova , Julia R.

AU - Tunik , Sergey P.

N1 - Hendi, Z.; Kozina, D.O.; Porsev, V.V.; Kisel, K.S.; Shakirova, J.R.; Tunik, S.P. Investigation of the N^C Ligand Effects on Emission Characteristics in a Series of Bis-Metalated [Ir(N^C)2(N^N)]+ Complexes. Molecules 2023, 28, 2740. https://doi.org/10.3390/molecules28062740

PY - 2023/3/17

Y1 - 2023/3/17

N2 - A series of bis-metalated phosphorescent [(N^C)2Ir(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 3LC 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.

AB - A series of bis-metalated phosphorescent [(N^C)2Ir(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 3LC 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.

KW - iridium complexes

KW - phosphorescence

KW - STRUCTURAL CHARACTERIZATION

KW - photophysical characteristics

KW - ligand effects

KW - structural characterization

UR - https://www.mendeley.com/catalogue/013d20b7-83c9-35a0-9efa-c722cab9ebcc/

U2 - 10.3390/molecules28062740

DO - 10.3390/molecules28062740

M3 - Article

C2 - 36985710

VL - 28

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 6

M1 - 2740

ER -