Synthesis and Characterization of Phosphorescent Cyclometalated Iridium Complexes
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- 1 March 2001
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 40 (7) , 1704-1711
- https://doi.org/10.1021/ic0008969
Abstract
The preparation, photophysics, and solid state structures of octahedral organometallic Ir complexes with several different cyclometalated ligands are reported. IrCl3·nH2O cleanly cyclometalates a number of different compounds (i.e., 2-phenylpyridine, 2-(p-tolyl)pyridine, benzoquinoline, 2-phenylbenzothiazole, 2-(1-naphthyl)benzothiazole, and 2-phenylquinoline), forming the corresponding chloride-bridged dimers, C∧N2Ir(μ-Cl)2IrC∧N2 (C∧Nis a cyclometalated ligand) in good yield. These chloride-bridged dimers react with acetyl acetone (acacH) and other bidentate, monoanionic ligands such as picolinic acid (picH) and N-methylsalicylimine (salH), to give monomeric C∧N2Ir(LX) complexes (LX = acac, pic, sal). The emission spectra of these complexes are largely governed by the nature of the cyclometalating ligand, leading to λmax values from 510 to 606 nm for the complexes reported here. The strong spin−orbit coupling of iridium mixes the formally forbidden 3MLCT and 3π−π* transitions with the allowed 1MLCT, leading to a strong phosphorescence with good quantum efficiencies (0.1−0.4) and room temperature lifetimes in the microsecond regime. The emission spectra of the C∧N2Ir(LX) complexes are surprisingly similar to the fac-IrC∧N3 complex of the same ligand, even though the structures of the two complexes are markedly different. The crystal structures of two of the C∧N2Ir(acac) complexes (i.e., C∧N = ppy and tpy) have been determined. Both complexes show cis-C,C‘, trans-N,N‘ disposition of the two cyclometalated ligands, similar to the structures reported for other complexes with a “C∧N2Ir” fragment. NMR data (1H and 13C) support a similar structure for all of the C∧N2Ir(LX) complexes. Close intermolecular contacts in both (ppy)2Ir(acac) and (tpy)2Ir(acac) lead to significantly red shifted emission spectra for crystalline samples of the ppy and tpy complexes relative to their solution spectra.Keywords
This publication has 34 references indexed in Scilit:
- Red and blue luminescent metallo-supramolecular coordination polymers assembled through π–π interactions †J. Chem. Soc., Dalton Trans., 2000
- Synthesis, Characterization, and Molecular Structure of Bis(tetraphenylcyclopentdienyl)rhodium(II)Organometallics, 1995
- Solvent effect on the photoinduced electron-transfer reactions between dicyanobis(polypyridine)ruthenium(II) complexes and tris(β-diketonato)ruthenium(III) complexesJournal of the Chemical Society, Faraday Transactions, 1995
- Studies on carbon-hydrogen activation. 9. Phosphine- and pyridine-assisted rearrangement of (ethene)iridium to hydrido(vinyl)iridium complexesOrganometallics, 1993
- Widely varying photophysical properties of ligand-nitrated bis(.mu.-chloro)tetrakis(2-phenylpyridinato)diiridium(III)Inorganic Chemistry, 1993
- The development of versions 3 and 4 of the Cambridge Structural Database SystemJournal of Chemical Information and Computer Sciences, 1991
- A new synthetic route to the preparation of a series of strong photoreducing agents: fac-tris-ortho-metalated complexes of iridium(III) with substituted 2-phenylpyridinesInorganic Chemistry, 1991
- Vibrational spectroscopic study of the temperature- and pressure-induced phase transition of norbornyleneThe Journal of Physical Chemistry, 1991
- The nature of .pi.-.pi. interactionsJournal of the American Chemical Society, 1990
- 2-Pyridyl complexes derived directly from pyridine and dodecacarbonyl-triangulo-triosmiumJ. Chem. Soc., Dalton Trans., 1975