Affiliations 

  • 1 Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
  • 2 Institute of Research Management and Services, Research and Innovation Management Complex, University of Malaya, Kuala Lumpur 50603, Malaysia
Inorg Chem, 2023 Feb 06;62(5):1942-1949.
PMID: 35925781 DOI: 10.1021/acs.inorgchem.2c01707

Abstract

A tetranuclear copper(I) complex, [Cu4{μ-(Ph2P)2NH}4(μ4-S)](PF6)2 (1), was synthesized. It was found to display intense and long-lived phosphorescence in the solid and solution states. The lowest-energy excited state was assigned as ligand-to-metal charge transfer (LMCT) [S2- → Cu4] mixed with some metal-centered (ds/dp) character. In addition, the phosphorescent state of this complex was found to be quenched by pyridinium acceptors via an oxidative electron-transfer quenching process. An excited-state reduction potential of -1.74 V versus saturated salt calomel electrode was estimated through oxidative quenching studies with a series of structurally related pyridinium acceptors, indicative of its strong reducing power in the excited state. From the transient absorption difference spectrum of the tetranuclear copper(I) sulfido complex and 4-(methoxycarbonyl)-N-methylpyridinium hexafluorophosphate, in addition to the characteristic absorption of the pyridinyl radical at ca. 395 nm, two absorption bands at ca. 500 and 660 nm were also observed. The former was assigned as an LMCT absorption [S2- → Cu4] and the latter as an intervalence charge-transfer transition, associated with the mixed-valence species CuI/CuI/CuI/CuII.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.