Article pubs.acs.org/IC
Iridium(III) Complexes with Phenyl-tetrazoles as Cyclometalating Ligands Filippo Monti,† Andrea Baschieri,‡ Isacco Gualandi,‡ Juan J. Serrano-Pérez,§ José M. Junquera-Hernández,§ Domenica Tonelli,‡ Andrea Mazzanti,‡ Sara Muzzioli,‡ Stefano Stagni,‡ Cristina Roldan-Carmona,§ Antonio Pertegás,§ Henk J. Bolink,§ Enrique Ortí,*,§ Letizia Sambri,*,‡ and Nicola Armaroli*,† †
Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, Via P. Gobetti, 101, I-40129, Bologna, Italy Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, Viale Risorgimento 4, I-40136, Bologna, Italy § Instituto de Ciencia Molecular, Universidad de Valencia, Catedrático José Beltrán 2, E-46980, Paterna, Spain ‡
S Supporting Information *
ABSTRACT: Ir(III) cationic complexes with cyclometalating tetrazolate ligands were prepared for the first time, following a two-step strategy based on (i) a silver-assisted cyclometalation reaction of a tetrazole derivative with IrCl3 affording a biscyclometalated solvato-complex P ([Ir(ptrz)2(CH3CN)2]+, Hptrz = 2-methyl-5-phenyl-2H-tetrazole); (ii) a substitution reaction with five neutral ancillary ligands to get [Ir(ptrz)2L]+, with L = 2,2′-bypiridine (1), 4,4′-di-tert-butyl-2,2′-bipyridine (2), 1,10-phenanthroline (3), and 2-(1-phenyl-1H-1,2,3triazol-4-yl)pyridine (4), and [Ir(ptrz)2L2]+, with L = tertbutyl isocyanide (5). X-ray crystal structures of P, 2, and 3 were solved. Electrochemical and photophysical studies, along with density functional theory calculations, allowed a comprehensive rationalization of the electronic properties of 1−5. In acetonitrile at 298 K, complexes equipped with bipyridine or phenanthroline ancillary ligands (1−3) exhibit intense and structureless emission bands centered at around 540 nm, with metal-to-ligand and ligand-to-ligand charge transfer (MLCT/LLCT) character; their photoluminescence quantum yields (PLQYs) are in the range of 55−70%. By contrast, the luminescence band of 5 is weak, structured, and blue-shifted and is attributed to a ligand-centered (LC) triplet state of the tetrazolate cyclometalated ligand. The PLQY of 4 is extremely low (
