Modulation of Internuclear Communication in Multinuclear Ruthenium(II) Polypyridyl Complexes

Abstract

The syntheses and characterisation of a series of mononuclear and dinuclear ruthenium polypyridyl complexes based on the bridging ligands 1,3-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]benzene, 1,4-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]benzene, 2,5-bis-[5-(2-pyridyl)-1H-1,2,4-triazol-3-yl]thiophene, 2,5-bis-[5-pyrazinyl-1H-1,2,4-triazol-3-yl]thiophene are reported. Electrochemical studies indicate that in these systems, the ground state interaction is critically dependent on the nature of the bridging ligand and its protonation state, with strong and weak interactions being observed for thiophene- and phenylene-bridged complexes, respectively.

Synthesis and characterisation of ruthenium complexes containing a pendent catechol ring

“…The new bands have been assigned as ligand-to-metal charge transfer (LMCT) bands on the basis of their energy and intensity and by comparison with structurally related complexes. [34][35][36] The expected depletion of 1 MLCT absorption bands is masked by the concomitant growth of bands at 435, 478 and 1167 nm for the bipy complex (see Fig. 9) and 420 and 1166 nm for the phen complex.…”

“…The new bands have been assigned as ligand-to-metal charge transfer (LMCT) bands on the basis of their energy and intensity and by comparison with structurally related complexes. 35,36,37 The expected depletion of 1 MLCT absorption bands is masked by the concomitant growth of bands at 435, 478 and 1167 nm for the bipy complex (see Figure 9) and 420 and 1166 nm for the phen complex. A full recovery of the original spectrum was observed upon electrochemical reduction of the oxidised species, confirming the reversibility of the first oxidation process and allowing it to be attributed to a metal centred oxidation process.…”

Energy Transfer Pathways in Dinuclear Heteroleptic Polypyridyl Complexes: Through-Space vs Through-Bond Interaction Mechanisms

“…The absence of an intervalence band in the absorption spectrum of mRu(II)Ru(III) is in agreement with the expected reduced electronic coupling for meta-vs para-based systems. 12 Similarly, during the oxidation of pOsOs, a weak band at 9400 cm -1 appears and subsequently disappears during the course of the oxidation but no such bands are observed for the mOsOs or their protonated forms…”

“…1,2,4-Triazolato anion based ligands hold significant advantages over other bridging systems, due to the possibility of both the formation of coordination isomers and an accessible acid/base chemistry, which enable both synthetic and environmental manipulation of the photochemical and photophysical properties of Ru(II) and Os(II) homo-and heterometallic complexes incorporating these ligands. [10][11][12][13] Indeed it is clear from these studies that ground state interaction between metal centers in the dinuclear complexes is mediated by the bridge through a hole transfer HOMO assisted superexchange mechanism.…”

Dinuclear metal complexes: multifunctional properties and applications

“…Photoinduced electron and energy transfer processes commonly occur in dinuclear metal systems, such as Ru(II)−Rh(III), 120,121 Ru(II)−Os(II), [122][123][124][125][126][127][128] Ru(II)−Ni(II), 129 Ru(II)−Zn(II), 130 Ru(II)−Cu(II), 131 Ru(II)−Ru(II), 64,67 Ir(III)−Ru(II), 125,132,133 Ir(III)−Pt(II), 129 Ir(III)−Eu(III), 134 Ir(III)−Ir(III) 56 . Therefore, bimetallic complexes are popular choices as donor-bridge-acceptor (D-B-A) systems for investigations of photoinduced electron and energy transfer process.…”