Search

The two series of ruthenium–indolizinone complexes prepared by Ru-mediated cyclization of pyridine-tethered alkynes represent the first examples of metalated indolizinone complexes. Joint experimental–theoretical investigation suggests an unconventional 5-endo-dig cyclization pathway as their formation mechanism. They also exhibit moderate cytotoxicity against several human cancer cell lines. [ABSTRACT FROM AUTHOR]

Copper(I) complexes with thermal activated delayed fluorescence (TADF) have attracted considerable attention for the development of emissive materials in organic light-emitting devices. However, many emissive CuI complexes are cationic emitters and cannot be vacuum-sublimed, a process used for device fabrication. This has limited their applications in devices. In this work we have developed a series of emissive charge-neutral CuI complexes with the general formula [Cu(2,9- Me2phen)(CNR){CNB(C6F5)3}] [R = 2,6-Me2C6H3, 2,6-iPr2C6H3, 2,4,6-Cl3C6H2, 2,4,6-Br3C6H2, 3,5-(CF3)2C6H3, 4-SF5C6H4] through the incorporation of a strong p-accepting anionic isocyanoborate ligand. All the complexes have been structurally characterized and their photophysical properties have been studied. [ABSTRACT FROM AUTHOR]

Water‐oxidation catalysts (WOCs) based on transition‐metal complexes often undergo oxidative degradation of the ligands, which leads to unidentifiable products. We report herein the use of a ruthenium(III) complex bearing a 2,2′‐bipyridyl (bpy)–bis(phenoxy) ligand, [Ru(L)(pic)2]+ [1, H2L=6,6′‐bis(2‐hydroxyphenyl)‐2,2′‐bipyridine, pic=4‐picoline] as a WOC. The phenoxy‐type ligand in 1 is readily oxidized by CeIV in aqueous acidic medium to give a ruthenium bpy–dicarboxylate complex ([Ru(bda)(pic)2]+, H2bda=2,2′‐bipyridine‐6,6′‐dicarboxylic acid) via ruthenium bpy–phenoxybenzoquinone (1′) and ruthenium bpy–bis(benzoquinone) (1′′) intermediates. All four ruthenium species can oxidize water; however, 1 and 1′ are rapidly oxidized to 1′′ by CeIV. On the other hand, 1′′ is robust enough that it is responsible for the initial phase of O2 evolution before it is finally oxidized to CO2 and [Ru(bda)(pic)2]+, which is a highly active WOC. [ABSTRACT FROM AUTHOR]

A new series of cyclometalated iridium(iii) complexes with isocyanoborate ligands [Ir(R2ppy)2(L)(CNBR′3)] (R = H or F; L = CNC6H4Cl-4 or PPh3; R′ = Ph, C6F5 or C6H4Cl-4), [Ir(biqb)(ppy)(CNBR′′3)] (R′′ = C6F5 or C6H4Cl-4) and {Ir(ppy)2(CN)n[CNB(C6F5)3]2−n}− (n = 0 or 1) have been synthesized and characterized. Three of these complexes have also been structurally characterized by X-ray crystallography. The photophysical and electrochemical properties of these complexes have been investigated. The effects of isocyanoborate ligands on the luminescence properties of these iridium(iii) complexes are also described. [ABSTRACT FROM AUTHOR]

The pyridine-containing ligands L1 and L2 react with Ni2+ ions to afford dinuclear triple-stranded helicate and tetrahedral cage supramolecular complexes, respectively; the two architectures exhibit contrasting reactivity towards electro- and photocatalytic proton reduction. [ABSTRACT FROM AUTHOR]

A new series of neutral isocyanoborato rhenium(I) diimine complexes [Re(CO)3(N^N)(CNBR3)], where N^N=bpy, 4,4′-Me2bpy, phen, 4,7-Me2phen, 2,9-Me2phen, 3,4,7,8-Me4phen; R=C6F5, C6H5, Cl, 4-ClC6H4, 3,5-(CF3)2C6H3, with various isocyanoborate and diimine ligands of diverse electronic and steric nature have been synthesized and characterized. The X-ray crystal structures of six complexes have also been determined. These complexes displayed intense bluish green to yellow phosphorescence at room temperature in dichloromethane solution. The photophysical and electrochemical properties of these complexes had been investigated. To elucidate the electronic structures and transitions of these complexes, DFT and TD-DFT calculations have been performed, which revealed that the lowest-energy electronic transition associated with these complexes originates from a mixture of MLCT [dπ(Re)→π*(N^N)] and LLCT [π(CNBR3)→π*(N^N)] transitions. [ABSTRACT FROM AUTHOR]

Polypyridyl and related ligands have been widely used for the development of water oxidation catalysts. Supposedly these ligands are oxidation-resistant and can stabilize high-oxidation-state intermediates. In this work a series of ruthenium(II) complexes [Ru(qpy)(L)2]2+ (qpy=2,2′:6′,2′′:6′′,2′′′-quaterpyridine; L=substituted pyridine) have been synthesized and found to catalyze CeIV-driven water oxidation, with turnover numbers of up to 2100. However, these ruthenium complexes are found to function only as precatalysts; first, they have to be oxidized to the qpy- N, N′′′-dioxide (ONNO) complexes [Ru(ONNO)(L)2]3+ which are the real catalysts for water oxidation. [ABSTRACT FROM AUTHOR]

A new tetradentate mixed aza-thioether macrocyclic ligand 2,6-dithia[7](2,9)-1,10-phenanthrolinophane ([13]ane(phenN2)S2) was successfully synthesized. Reacting metal precursors [Fe(CH3CN)2(OTf)2], Ni(ClO4)2·6H2O, and Cu(ClO4)2·6H2O with one equivalent of [13]ane(phenN2)S2 afforded [Fe([13]ane(phenN2)S2)(OTf)2] (1), [Ni([13]ane(phenN2)S2)](ClO4)2 (2(ClO4)2), and [Cu([13]ane(phenN2)S2)(OH2)](ClO4)2 (3(ClO4)2), respectively. The structures of [13]ane(phenN2)S2 and all of its metal complexes were investigated by X-ray crystallography. The [13]ane(phenN2)S2 was found to behave as a tetradentate ligand via its donor atoms N and S. [ABSTRACT FROM AUTHOR]

With a series of chiral pyridine-based tetradentate pyridyl-thiazole ligands L , three types of binuclear helical metal complexes were synthesized. They were the Re(I) single-stranded complexes of formula [Re 2 ( L )(CO) 6 Br 2 ], the Ag(I) double-stranded complexes of formula [Ag 2 ( L ) 2 ](ClO 4 ) 2 and the Cu(II) triple-stranded complex of formula [Cu 2 ( L ) 3 ](ClO 4 ) 4 . Each type of them has been characterized using CD spectroscopy and if possible 1 H NMR spectroscopy. Three single crystal structures, one from each type, have been determined. [ABSTRACT FROM AUTHOR]

A series of luminescent rhenium(I) phenanthroline complexescontaining benzoxazol-2-ylidene ligands with the general formula {Re(CO)3(phen)[CN(X)C6H4-2-O]}+and cis,trans-{Re(CO)2(phen)(L)[CN(H)C6H4-2-O]}+(X = H, methyl; phen = 1,10-phenanthroline; L = PPh3, PPh2Me, P(OEt)3) have been synthesized andcharacterized. The X-ray crystal structures of most of the carbenecomplexes and some of their synthetic precursors have also been determined.A new synthetic methodology for the preparation of dicarbonyl rheniumdiimine synthetic precursors with a labile acetonitrile ligand, [Re(CO)2(phen)(PR3)(MeCN)]+, was developed.Photophysical study shows that these carbene complexes display a greento red 3MLLCT [dπ(Re) → π*(N–N)]phosphorescence at room temperature. The N-deprotonations of the benzoxazol-2-ylideneligand in these complexes were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Pyridylindole ligand and its chloro substituted derivatives have been synthesized and incorporated into the square planar bis(phenylisocyano) rhodium(I) complexes to give a series of neutral rhodium(I) complexes with general formula of [Rh(X-pyind)(CNR)2] (R=2,6-(CH3)2-4-BrC6H2, 2,4-Cl2-6-(CH3O)C6H2, 2,4,6-Br3C6H2, 2,4,6-Cl3C6H2; L=2-(2′-pyridyl)indole, 5-chloro-2-(2′-pyridyl)indole, 4,6-dichloro-2-(2′-pyridyl)indole). The structures of two complex precursors [Rh(cod)(Cl-pyind)] and [Rh(cod)(Cl2pyind)], and the target complex [Rh(pyind)(CNC6H2-2,4-Cl2-6-(OCH3))2] were determined by X-ray crystallography. The UV–vis absorption properties of these complexes and their responses towards the change of temperature were also investigated. [Copyright &y& Elsevier]

Abstract: The cobalt(III) macrocyclic Schiff-base complex, [CoIII(CR)Cl]ClO4 (CR = 2,12-dimethyl-3,7,11,17-tetra-azabicyclo[11.3.1]-heptadeca-1(17),2,11,13,15-pentaene), is an active catalyst for the electrocatalytic proton reduction to generate dihydrogen in both acetonitrile and 100% aqueous solution (at −0.57 and −0.85 V vs SCE, respectively), using p-cyanoanilinium tetrafluoroborate and acetic acid as proton sources, respectively. Bulk electrolysis confirmed that dihydrogen is produced with >90% Faradaic yields and >50 TON in both solvents. [CoIII(CR)Cl2]ClO4 also catalyzes photo-driven (λ > 390 nm) hydrogen production in aqueous acetonitrile at TON of 180 (not optimized), using [IrIII(ppy)2(bpy)]PF6 as the photosensitizer, triethanolamine (TEOA) as the sacrificial donor and acetic acid as the proton source. [Copyright &y& Elsevier]

Abstract: New chiral dipyridine ligands with an axially unfixed 1,1′-biphenyl bridge were prepared via homocoupling of bromophenyl pyridines. The conformeric ratios of the free ligands in solution and their coordination properties towards metal ions were studied by NMR spectroscopy. X-Ray crystallography of the silver(I) and copper(I) complexes showed 1:1 metal to ligand complexes and S planar chirality. Interestingly, the biphenyl ligands show a 1:2 stepwise binding towards most ammonium ions tested with strong fluorescence enhancement, but a selectively 1:1 binding towards l-ornithine methyl ester hydrochloride with no fluorescence enhancement. [Copyright &y& Elsevier]