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The report concerns expansion of the previously developed M-[O,N,C] [pyridine-2-phenolate-6-(σ-aryl)] catalyst system into rigid, coplanar bimetallic assemblies, which afford metal–metal distances that are predetermined yet amenable for cooperativity, as well as locked-in "syn" orientation of binding sites that offer the same direction of access for substrates. The binuclear complexes are generated in a regioselective manner to yield para hydrogen atoms (not ortho) at the central μ-aryl moiety, and have been characterised by multinuclear NMR spectroscopy. The "anti" (showing opposite directions of access) and mononuclear analogues have also been prepared for comparison purposes. Six syn-type bimetallic derivatives of Ti, Zr and Hf have been characterised by X-ray crystallography, to reveal metal–metal separations of 6.3–6.7 Å. For ethylene and ethylene/1-octene polymerisation reactions in conjunction with trityl borate, the syn-Ti2 catalysts display superior efficiencies and produced polymers with higher Mw values than for the anti and mono-Ti congeners, thus indicating the possibility of favourable enchainment interactions and cooperative reactivity. [ABSTRACT FROM AUTHOR]

Although multitargeted PtIV anticancer prodrugs have shown significant activities in reducing drug resistance, the types of bioactive ligands and drugs that can be conjugated to the Pt center remain limited to O‐donors. Herein, we report the synthesis of PtIV complexes bearing axial pyridines via ligand exchange reactions. Unexpectedly, the axial pyridines are quickly released after reduction, indicating their potential to be utilized as axial leaving groups. We further expand our synthetic approach to obtaining two multitargeted PtIV prodrugs containing bioactive pyridinyl ligands: a PARP inhibitor and an EGFR tyrosine kinase inhibitor; these conjugates exhibit great potential for overcoming drug resistance, and the latter conjugate inhibits the growth of Pt‐resistant tumor in vivo. This research adds to the array of synthetic methods for accessing PtIV prodrugs and significantly increases the types of bioactive axial ligands that can be conjugated to a PtIV center. [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]

M8L12 cubic cages (M = MnII, ZnII or CdII), with all eight metal ions having all facial Δ or facial Λ configurations and having an encapsulated anion, were prepared by the self-assembly of m-xylene-bridged imidazolyl-imine ligands and MX2 (X = PF6−, SbF6−, TfO−) salts; the encapsulated anion exchange with different anions (SbF6−, Tf2N−, NO3−, TsO−) was studied and the results with NO3− and TsO− indicate that anions on the cage surfaces affect the encapsulated anion exchange and the occupancy of the cage. [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]

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 newclass of neutral bis(isocyanoborato) bis(bipyridyl)Os(II) complexes with the general formula of [Os(N–N)2(CNBR3)2] (N–N = bpy, 4,4′-Me2bpy; R = C6F5, C6H5) were prepared with simple synthetic methodologies. One of thesecomplexes was structurally characterized by X-ray crystallography.Unlike most of the neutral bis(bipyridyl) Os(II) complexes, whichare very weakly emissive or nonemissive, these isocyanoborato complexesdisplayed intense orange to red phosphorescence with a luminescentquantum yield up to 0.09 in CH2Cl2solutionat room temperature. The photophysical and electrochemical propertiesof these complexes were also investigated. Detailed photophysicalstudy showed that these complexes exhibited significantly enhancedemission properties over other reported neutral bis(bipyridyl) Os(II)complexes. In addition, it also revealed that the photophysics, electrochemistry,and excited state properties can be fine-tuned or modified throughthe functionalization of isocyanoborate ligands. [ABSTRACT FROM AUTHOR]

To improve the emission and excited-state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR3)2(CN)2( $\widehat{NN}$)] and K[Ru(PR3)(CN)3( $\widehat{NN}$)], respectively, were developed. These complexes could be readily synthesized through the ligand-substitution reaction of K2[Ru(CN)4(PR3)2] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well-studied tetracyanoruthenate systems. [ABSTRACT FROM AUTHOR]

A series of rhenium complexes with acetylamino- and trifluoroacetylamino-containing 1,10-phenanthroline ligands have been synthesized, characterized and their photophysical and electrochemical properties studied. These complexes were found to show significant UV-vis and emission changes on addition of CN−, F−and AcO−anions. Their reactivity towards CN−, F−and AcO−anions, was also investigated by UV-vis, emission and 1H NMR spectroscopy. The reaction product between the trifluoroacetylamino-containing 1,10-phenanthroline ligand and the CN−anion has also been structurally characterized by X-ray crystallography. [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]

Reaction of [RuII(PR3)3Cl2] with 2-methyl-8-quinolinolate (MeQ)in thepresence of Et3N in MeOH produced the neutral carbonylhydrido complexes [RuII(MeQ)(PR3)2(CO)(H)] (R = Ph (1), MeC6H4(2), MeOC6H4(3)). An analogousreaction occurs between [RuII(PPh3)3Cl2] and MeQH in ethanol to give [RuII(MeQ)(PPh3)2(CO)(CH3)] (4). The carbonyl,hydride, and methyl ligands of these complexes are most likely derivedfrom the decarbonylation of ROH. Reaction of [RuII(PPh3)3(CO)(H)2] with 5-substituted quinolinolatoligands (XQ, X = H, Cl, Ph) produced the neutral complexes [RuII(XQ)(PPh3)2(CO)(H)] (XQ = Q (5), ClQ (6), PhQ (7)). Treatmentof 1and 5–7with excessKCN in MeOH following by metathesis with PPh4Cl affordedPPh4+salts of the anionic carbonyl dicyanocomplexes [RuII(XQ)(CO)(CN)2(PPh3)]−(XQ = MeQ (8), Q (9) ClQ (10), PhQ (11)). Under similar conditions,reaction of 1with excess CyNC in the presence of NH4PF6afforded [RuII(MeQ)(CyNC)2(CO)(PPh3)]+(12). All complexeshave been characterized by IR, ESI/MS, 1H NMR and elementalanalysis. The crystal structures of complexes 3, 4, 8, and 12have been determinedby X-ray crystallography. The UV and emission spectra of these complexeshave also been investigated. All complexes exhibit short-lived quinolinolate-basedLC fluorescence in solution at room temperature and dual emissionsderived from LC fluorescence and phosphorescence at 77 K glassy medium.These emissions are relatively insensitive to the nature of the ancillaryligands but are readily tunable by varying the substituents on thequinolinolato ligand. [ABSTRACT FROM AUTHOR]

Abstract: The rich excited state properties associated with the long-lived triplet metal-to-ligand charge transfer excited state of rhenium(I) tricarbonyl diimine complexes have been investigated for many years. Through judicious design and functionalization of the ligands with various functional moieties, these complexes can be used for different applications. However, further modification of the physical and excited state properties with their functions being maintained are challenging. In view of this, we have designed several new classes of isocyano rhenium(I) diimine complexes with readily tunable structural features. In this review article, our recent work on the syntheses, characterizations and photophysical properties of these tunable rhenium(I) diimine luminophores are discussed. [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]

Abstract: Three new optically pure C 1-terpyridine ligands (L1–3) were prepared and the copper(II) complexes, of formula [Cu(L)Cl2], the rhodium(III) complexes, of formula [Rh(L)Cl3], and the ruthenium(II) complexes, of formula cis- or trans-[Ru(L)(X)Cl2] (X=DMSO or CO), were synthesized. Structures of a chiral C 1-ligand, a copper complex, a rhodium complex and a ruthenium DMSO complex were analysed using X-ray crystal structure analysis. The copper, rhodium and ruthenium complexes were shown to be precursors of catalysts for cyclopropanation. Reaction of [Cu(L)Cl2], [Rh(L)Cl3] or cis- or trans-[Ru(L)(X)Cl2] with AgOTf converted the complex to catalyst, which in the case of trans-[Ru(L)(CO)Cl2] gave enantioselectivities of up to 67% ee for the cis-isomers of styrene cyclopropanes with t-butyl diazoacetate. Comparisons with C 2-analog of copper, rhodium and ruthenium catalysts were made. [Copyright &y& Elsevier]