Localized ³MLCT Transitions in [Ru(bpy)_3-x(bpy-6,6‘-d₂)_x]²⁺ (x = 0−3, bpy = 2,2‘-Bipyridine). Probing Minimally Perturbed Chromophores

Abstract

Luminescence and excitation spectra in the region of the lowest-energy 3 MLCT electronic origins of the specifically deuterated complexes [Ru(bpy) 3-x (bpy-6,6′-d 2 ) x ] 2+ (x ) 0-3) in [Zn(bpy) 3 ](ClO 4 ) 2 and in the neat [Ru(bpy) 3-x (bpy-6,6′-d 2 ) x ](PF 6 ) 2 (x ) 0-3) crystals are reported. The deuteration of the 6,6′ positions represents a minimal variation of the bpy ligand. The x ) 1, 2 systems show independent 3 MLCT transitions to the bpy-6,6′-d 2 and the bpy ligand. Intensity ratios of luminescence involving the bpy-6,6′-d 2 ligand or the bpy ligand in the x ) 1, 2 systems vary as a function of temperature in accord with expectations. Measurements are made providing an estimate of ∼(2.1 ( 0.8) × 10 9 s -1 for the intramolecular 3 MLCT excitation transfer from bpy-6,6′-d 2 to bpy. We also report a simple high-yield method to deuterate the 6,6′ positions of the bpy ligand.

Application of the Langmuir−Blodgett Technique to Prepare a Clay−Metal Complex Hybrid Film

“…The absorption band at 460-430 nm was assigned to be the metal-to-ligand charge transfer (MLCT) band. 16 The dichroic ratio at 450 nm, A ⊥ /A | , was obtained to be 0.75 ( 0.05. The MLCT band is the composite of three transitions from a central Ru(II) ion to three ligands.…”

The effect of deuteriation on the emission lifetime of inorganic compounds

“…One of the most common methods of deuteriation is that of acidic hydrogens, such as N-H [11], O-H [12,13], terminal acetylenes [14], α-methylenic protons [15][16][17], porphyrins [18,19] and heteroaromatic N-oxides such as 2,2'-bipyridyl-5 N,N-dioxide [20]. This H-D exchange method can be effected simply by dissolution in D 2 O (or in a binary protic solvent system using for example MeOD or d 6 -DMSO) with heat, pressure and/or acid/base [14].…”

“…Low temperature (< 5 K) high resolution emission studies on a series of platinum group complexes have been carried out by Yersin et al [60(a)] and Krausz et al [16,88].…”

2,2/-Bipyridyl Chelated Ru(II)-Annulated NHC Complex of 1-Methyl-2-Pyridin-2-Yl-2H-Imidazo[1,5-a]Pyridin-4-Ylidene: Synthesis, Structure, Optical Properties, and DFT Interpretation

“…It is of extreme importance to know that the distance between the donor hydrogen atoms and the acceptor fluorine atoms, lying in the range of 2.42 ~ 2.47 Å, is sufficiently short in comparison to the sum of the van der Waals radii of the participating atoms (the sum is 2.67 Å). [67] This maybe on account of the favorable electrostatic contributions that govern interactions between the negatively charged fluorine atoms, of the anionic moiety, and the positively charged metal-ligand complex, that induce the electropositive character on the H-atoms of the ligand 22) close ring motif, [68] which further propagates along the bc-plane (Fig. 3).…”

“…[13][14][15][16][17] Many groups have contributed to the improvement of the photophysical properties of such complexes, either by lowering the energy of the triplet metalligand charge transfer transitions (MLCT) excited state, or by increasing the MC state energy, the common objective being to place the two states as far as possible from one another. [18][19][20][21][22][23] Replacement of one or several pyridine ligand sites by Nheterocyclic carbenes (NHCs) has received surprisingly little attention. [24][25][26][27] To gain an insight into the photochemical reactions of carbene complexes, it is necessary to characterize the lowest-lying electronic excited states and their photophysical deactivation mechanisms.…”