Tris-heteroleptic iridium complexes based on cyclometalated ligands with different cores

Cudré, Yanouk, Franco de Carvalho, Felipe, Burgess, Gregory R., Male, Louise, Pope, Simon J. A. ORCID: https://orcid.org/0000-0001-9110-9711, Tavernelli, Ivano and Baranoff, Etienne 2017. Tris-heteroleptic iridium complexes based on cyclometalated ligands with different cores. Inorganic Chemistry -American Chemical Society- 56 (19) , pp. 11565-11576. 10.1021/acs.inorgchem.7b01307

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Abstract

A series of tris-heteroleptic iridium complexes of the form [Ir(C^N1)(C^N2)(acac)] combining 2-phenylpyridine (ppy), 2-(2,4-difluorophenyl)pyridine (dFppy), 1-phenylpyrazole (ppz), and 1-(2,4-difluorophenyl)pyrazole (dFppz) as the C^N ligands have been synthesized and fully characterized by NMR, X-ray crystallography, UV–vis absorption and emission spectroscopy, and electrochemical methods. It is shown that “static properties” (e.g., absorption and emission spectra and redox potentials) are primarily dictated by the overall architecture of the complex, while “dynamic properties” (e.g., excited-state lifetime and radiative and nonradiative rate constants) are, in addition, sensitive to the specific positioning of the substituents. As a result, the two complexes [Ir(dFppy)(ppz)(acac)] and [Ir(ppy)(dFppz)(acac)] have the same emission maxima and redox potentials, but their radiative and nonradiative rate constants differ significantly by a factor ∼2. Then acetylacetonate (acac) was replaced by picolinate (pic), and two pairs of diastereoisomers were obtained. As expected, the use of pic as the ancillary ligand results in blue-shifted emission, stabilization of the oxidation potential, and improvement of the photoluminescence quantum yield, and only minor differences in the optoelectronic properties are found between the two diastereoisomers of each pair.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	American Chemical Society
ISSN:	0020-1669
Date of First Compliant Deposit:	27 September 2017
Date of Acceptance:	18 September 2017
Last Modified:	30 Nov 2024 08:15
URI:	https://orca.cardiff.ac.uk/id/eprint/105020

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