Issue 10, 2011

Switching of excited states in cyclometalated platinum complexes incorporating pyridyl-acetylide ligands (Pt–C[triple bond, length as m-dash]C–py): a combined experimental and theoretical study

Abstract

This article presents the design of cyclometalated platinum(II) complexes incorporating pyridyl-appended acetylide ligands of the form Pt–C[triple bond, length as m-dash]C–py, acting either as sites for protonation or methylation reactions or as a host receptor for binding metal cations. The complexes studied are Pt(t-Bu2phbpy)(–C[triple bond, length as m-dash]C–py), 2, which can undergo protonation at the pyridyl N; its cationic N-methylated derivative [Pt(t-Bu2phbpy)(–C[triple bond, length as m-dash]C–pyMe)]+, 4, which serves as a model of the N-protonated species; and a derivative in which the pyridyl ring is incorporated into a macrocyclic diamide-crown ether ligand (3). The co-ligand t-Bu2phbpy is a cyclometalated, N⁁N⁁C-coordinated phenylbipyridine ligand carrying tert-butyl groups at the 4-positions of the pyridyl rings. The photophysical properties of the neutral compounds 2 and 3 have been compared to those of the pyridinium, methyl-pyridinium or metal-complexed species (namely 2-H++, 4 and 3-Pb2+2+). Detailed TD-DFT calculations provide a theoretical basis to account for the experimentally-observed changes upon protonation/methylation/complexation. The joint TD-DFT and experimental studies provide evidence for an unprecedented molecular switch in the nature of the excited state (from mixed L′LCT/MLCT to ML′CT) in which the acceptor ligand in the CT process switches from being the N⁁N⁁C ligand to the pyridyl acetylide.

Graphical abstract: Switching of excited states in cyclometalated platinum complexes incorporating pyridyl-acetylide ligands (Pt–C [[triple bond, length as m-dash]] C–py): a combined experimental and theoretical study

Supplementary files

Article information

Article type
Paper
Submitted
10 Mar 2011
Accepted
31 May 2011
First published
27 Jun 2011

New J. Chem., 2011,35, 2196-2202

Switching of excited states in cyclometalated platinum complexes incorporating pyridyl-acetylide ligands (Pt–C[triple bond, length as m-dash]C–py): a combined experimental and theoretical study

C. Latouche, P. Lanoë, J. A. G. Williams, V. Guerchais, A. Boucekkine and J. Fillaut, New J. Chem., 2011, 35, 2196 DOI: 10.1039/C1NJ20225A

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