Tuning the electrochemiluminescent properties of iridium complexes of N-heterocyclic carbene ligands. Issue 2 (13th December 2018)

• Record Type: Journal Article
• Authors: Quan, Linh M.; Stringer, Bradley D.; Haghighatbin, Mohammad A.; Agugiaro, Johnny; Barbante, Gregory J.; Wilson, David J. D.; Hogan, Conor F.; Barnard, Peter J.
• Is Part Of: Dalton transactions. Volume 48:Issue 2(2018)
• Page Start: 653
• Page End: 663
• Publication Date: 2018-12-13
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt04433c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A series of electrochemiluminescent iridium(iii ) N-heterocyclic carbene complexes have been prepared to tune electrochemical and spectroscopic behaviour. Abstract : A series of five heteroleptic Ir(iii ) complexes of the general form Ir(dfppy)2 (C^C) have been prepared (where dfppy represents 2-(2, 4-difluorophenyl)pyridine and C^C represents a bidentate cyclometalated phenyl substituted imidazolylidene ligand). The cyclometalated phenyl ring of the imidazolylidene ligand was either unsubstituted or substituted with electron donating (OMe and Me) or electron withdrawing (Cl and F) groups in the 2 and 4 positions. The synthesised Ir(iii ) complexes have been characterised by elemental analysis, NMR spectroscopy, cyclic voltammetry and electronic absorption and emission spectroscopy. The molecular structures for four Ir(iii ) complexes were determined by single crystal X-ray diffraction. Each of the Ir(iii ) complexes exhibited intense photoluminescence in acetonitrile solution at room temperature with quantum yields ( Φ PL ) ranging from 58% to 86%. Cyclic voltammetry experiments revealed one oxidation process (formally ascribed to the metal centre), and two ligand-based reductions for each complex. Complexes1–5 gave moderate to intense annihilation and co-reactant electrochemiluminescence (ECL). Consideration of the electrochemical, spectroscopic and theoretical investigations provide insights into the electrochemiluminescence behaviour.