Metal to Ligand Charge Transfer excitations

J Ru(bpy), the metal-to-ligand charge-transfer excited state... 

W. J. Vining, J. V. Caspar, and T. J. Meyer, Influence of environmental effects on excited state lifetimes. The effect of ion pairing on metal-to-ligand charge transfer excited states, J. Phys. Chem. 89, 1095-1099(1985). 

Figure 2. Schematic representation of some relevant ground and excited-state properties of Ru(bpy)j. MLCT and MLCT are the spin-allowed and spin-forbidden metal-to-ligand charge transfer excited states, responsible for the high intensity absorption band with = 450 nm and the luminescence band with = 615 nm, respectively. The other quantities shown are intersystem crossing efficiency energy (E°°) and lifetime (x) of the MLCT state luminescence quantum yield ( ) quantum yield for ligand detachment (O,). The reduction potentials of couples involving the ground and the MLCT excited states are also indicated.

The reaction mechanism was proposed to involve electron transfer from the d-7i metal to ligand charge transfer excited state (MLCT transition) to the chlorinated solvent,... 

With the exception of a few highly studied states, such as, for example, the redox active lowest metal-to-ligand charge transfer excited state (MLCT) in the [Ru(bipyridine)3]2t cation, or the ligand field active 2E state of Cr(IlI), we know relatively little about these excited states. An enormous body of knowledge is waiting to be explored. 

The photoluminescence of dipyridophenazine complexes of ruthenium ) in the presence and absence of DNA has been well-characterized (38-40, 46-52). Excitation of the dppz complexes with visible light (440 nm) leads to localized charge transfer from the metal center (39, 40). In aqueous solution, the emission resulting from the metal-to-ligand charge-transfer excited state is deactivated via nonradiative energy transfer... 

Three basic types of excited states need to be considered here (i) metal to ligand charge transfer excited states (MLCT) in which an electron is excited from a dn... 

A great deal of work on Ru-modified proteins has employed the Ru(bpy)2(im) (HisX) " (bpy = 2,2 -bipyridine im = imidazole) label [16, 21, 26] (Figure 2). In addition to favorable ET properties, these Ru-bpy complexes have long-lived, luminescent metal-to-ligand charge-transfer excited states that can be prepared with... 

Metal-to-ligand Charge Transfer Excited States... 

Damrauer, N. H. McCusker, J. K. Ultrafast dynamics in the metal-to-ligand charge transfer excited-state evolution of Ru(4,4 -diphenyl-2,2 - bipyridine)(3) (2+). J. Phys. Chem. A 1999, 103, 8440-8446. 

Vlcek, A. Mechanistic roles of metal-to-ligand charge-transfer excited states in organometallic photochemistry. Coord. Chem. Rev. 1998, 177, 219-256. 

METAL-TO-LIGAND CHARGE TRANSFER EXCITED STATES 553... 

Metal-to-ligand charge-transfer excitations (MLCT), which are observed in species with metals in relatively low oxidation states with ligands that have low lying empty orbitals (in general 7t -orbitals). 

Luminescent coordination compounds continue to attract considerable attention. Zink recently reported a new mixed-ligand copper(I) polymer that shows interesting photoluminescence (232). The complex [CuCl(L44)Ph3P] consists of a one-dimensional chain lattice of metal ions bridged by both Cl" ions and pyrazine molecules. The compound shows conductivity of less than 10-8 S cm 1. The absorption spectrum of the complex shows a band at 495 nm, which could be interpreted as the promotion of an electron from the valence band to the conduction band. On the basis of resonance Raman spectra, the lowest excited state in the polymer is assigned to the Cu(I)-to-pyrazine metal-to-ligand charge-transfer excited state. 

Metal-to-Ligand Charge Transfer Excited States.164... 

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