Luminescent 2-phenylbenzothiazole cyclometalated Pt II and Ir III complexes with chelating P^O ligands

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 51; no. 1; pp. 274 - 285
• Main Authors: Gómez de Segura, David, Lara, Rebeca, Martínez-Junquera, Mónica, Lalinde, Elena, Moreno, M Teresa
• Format: Journal Article
• Language: English
• Published: England 20.12.2021
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/D1DT03531B

Two series of cyclometalated Pt and Ir complexes with general formulas [Pt(pbt){PPh (R)-κ , }] (2a-2c) and [Ir(pbt) {PPh (R)-κ , }] (3a-3c), where Hpbt is 2-phenylbenzothiazol and PPh (R) is a diphenylphosphino donor functionalized deprotonated acid (R = -C H CO a, -C H SO b, CH CH CO c) are presented. The structures of 1, 2a-2c, 3a and 3b were confirmed by single X-ray diffraction analyses, and the intermolecular interactions in 2a were studied using Hirshfeld surface analysis and non-covalent interaction (NCI) methods on its X-ray structure. Their photophysical properties were investigated by absorption and emission analyses [CH Cl , solid (298, 77 K) and doped polystyrene (PS) films], supported by TD-DFT calculations on 1, 2a-2c and 3a. The Pt complexes exhibit bright phosphorescence in the region 525-542 nm, ascribed to a mixed IL/ MLCT excited state with a predominant IL contribution. The Ir derivatives (3a-3c) show orange photoluminescence (535-584 nm, 298 K), blue shifted at 77 K (527-560 nm), originated from the admixture of IL/ MLCT/ LLCT excited states. Interestingly, the photoluminescence quantum yields of the Pt complexes 2a-2c ( = 46.5-66.5%) in PS films are remarkably higher than those of the corresponding iridium complexes ( = 17.3-32%) and the precursor 1 ( = 17%). The calculated MC- IL/ MLCT energy gap for 2a and 3a accounts for the higher quantum yield of the Pt in relation to the Ir complex.