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The invention of efficient systems for the photocatalytic reduction of CO 2 comprising earth-abundant metal catalysts is a promising approach for the production of solar fuels. One bottleneck is to design highly selective and robust molecular complexes that are able to transform the CO 2 gas. The Cu II quaterpyridine complex [Cu(qpy)] 2+ (1) is found to be a highly efficient and selective catalyst for visible-light driven CO 2 reduction in CH 3 CN using [Ru(bpy) 3 ] 2+ (bpy: bipyridine) as photosensitizer and BIH/TEOA (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole/triethanolamine) as sacrificial reductant. The photocatalytic reaction is greatly enhanced by the presence of H 2 O (1-4 % v/v), and a turnover number of >12 400 for CO production can be achieved with 97 % selectivity, which is among the highest of molecular 3d CO 2 reduction catalysts. Results from Hg poisoning and dynamic light scattering experiments suggest that this photocatalyst is homogenous. To the best of our knowledge, 1 is the first example of molecular Cu-based catalyst for the photoreduction of CO 2 ., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of a triazole ligand, 2-(1H-1,2,3-triazol-4-yl)pyridine (L1), with 2-bromopyridine afforded three new ligands, 2,2′-(1H-1,2,3-triazole-1,4-diyl)dipyridine (L2), 2,2′-(2H-1,2,3-triazole-2,4-diyl)dipyridine (L3) and 2,2′-(1H-1,2,3-triazole-1,5-diyl)dipyridine (L4). A series of luminescent mononuclear copper(I) complexes of these ligands [Cu(Ln)(P^P)](ClO4) [n = 1, P^P = (PPh3)2 (1); n = 1, P^P = POP (2); n = 2, P^P = (PPh3)2 (3); n = 2, P^P = POP (4); n = 3, P^P = (PPh3)2 (5); n = 3, P^P = POP (6); n = 4, P^P = (PPh3)2 (9); n = 4, P^P = POP (10)] have been obtained from the reaction of Ln with [Cu(MeCN)4]ClO4 in the presence of PPh3 and POP. L3 was also found to form dinuclear compounds [Cu2(L3)(PPh3)4](ClO4)2 (7) and [Cu2(L3)(POP)2](ClO4)2 (8). All of the Cu(I) compounds have been characterized by IR, UV/vis, CV, 1H NMR, and 31P{1H} NMR. The molecular structures of 1–3, 5, and 7 have been further determined by X-ray crystallography. In CH2Cl2 solutions, these Cu(I) complexes exhibit tunable green to orange emissions (563–621 nm) upon excitation at λex = 380 nm. In the solid state, these complexes show intense emissions and it is interesting to note that 1 and 3 are blue-light emitters. Density functional theory (DFT) calculations revealed that the lowest energy electronic transition associated with these complexes predominantly originates from metal-to-ligand charge transfer transitions (MLCT). [ABSTRACT FROM AUTHOR]

A new series of luminescent phosphine copper(I) complexes with cyano- and hydroxyl-substituted 2,2′-bipyridine ligands [CuI(bpy(CN)2)(P(PhX)3)2](ClO4) [X = H (1); Me (2); Cl (3)], [CuI(bpy(CN)2)(POP)](ClO4) (4), [CuI(bpy(OH)2)(PPh3)2](ClO4) (5) and [CuI(bpy(OH)2)(POP)](ClO4) (6) have been synthesized and characterized. Three of these complexes have been structurally characterized by using X-ray crystallography. The effect of the attaching –CN and –OH groups at the ortho-positions of bpy ligand was investigated. In CH2Cl2 solution, these complexes show yellow to orange phosphorescence, with the emission maxima not only sensitive to the electronic nature of the bipyridine ligands, but also considerably varied with the modification of phosphine ligands. In addition, these complexes show intense tunable green to yellow emissions in their solid state. To elucidate the electronic structures and transitions of these complexes, density functional theory (DFT) calculations on representative examples revealed that the lowest energy electronic transition associated with these complexes predominantly originates from metal-to-ligand charge transfer transitions (MLCT). [ABSTRACT FROM AUTHOR]

The invention of efficient systems for the photocatalytic reduction of CO2 comprising earth-abundant metal catalysts is a promising approach for the production of solar fuels. One bottleneck is to design highly selective and robust molecular complexes that are able to transform the CO2 gas. The CuII quaterpyridine complex [Cu(qpy)]2+ ( 1) is found to be a highly efficient and selective catalyst for visible-light driven CO2 reduction in CH3CN using [Ru(bpy)3]2+ (bpy: bipyridine) as photosensitizer and BIH/TEOA (1,3-dimethyl-2-phenyl-2,3-dihydro-1 H-benzo[ d]imidazole/triethanolamine) as sacrificial reductant. The photocatalytic reaction is greatly enhanced by the presence of H2O (1-4 % v/v), and a turnover number of >12 400 for CO production can be achieved with 97 % selectivity, which is among the highest of molecular 3d CO2 reduction catalysts. Results from Hg poisoning and dynamic light scattering experiments suggest that this photocatalyst is homogenous. To the best of our knowledge, 1 is the first example of molecular Cu-based catalyst for the photoreduction of CO2. [ABSTRACT FROM AUTHOR]

A series of triphenylphosphine Cu(I) complexes with various diimine ligands, [Cu(N–N)(PPh 3 ) 2 ](ClO 4 ) [N–N = dmp ( 2 ); Ph 2 Phen ( 3 ); Ph 2 dmp ( 4 ); dpq ( 5 ); dppz ( 6 ); phenCN ( 7 ); phenOH ( 8 )] are synthesized by the ligand substitution reactions of [Cu(MeCN) 4 ](ClO 4 ) with 2 mole equiv. of PPh 3 ligand and 1.2 mole equiv. of diimine ligand. {Cu( dpq )[P(XPh) 3 ] 2 }(ClO 4 ) [X = Me ( 5a ); OMe ( 5b ); Cl ( 5c )] and {Cu( phenOH )[P(XPh) 3 ] 2 }(ClO 4 ) [X = Me ( 8a ); OMe ( 8b )] are also obtained by using various substituted phosphine ligands. These mixed-ligand complexes have been characterized using 1 H and 31 P NMR spectroscopy, IR spectroscopy, mass spectrometry and elemental analysis. Three of these complexes have been structurally characterized by X-ray crystallography. The photophysical and electrochemical properties of these complexes have been studied. These complexes exhibit MLCT phosphorescence with emission energy, lifetimes and quantum yields showing strong dependence on the nature of diimine and phosphine ligands. In particular, both the electronic and steric effects of the substituting groups in phosphine ligands are also found to affect the emission properties of the complexes. Our study provides structural-properties information for the future design of luminescent Cu(I) complexes. [ABSTRACT FROM AUTHOR]