A C-terminal domain of the membrane copper pump Ctr1 exchanges copper(I) with the copper chaperone Atx1

A cloned C-terminal domain of the yeast high-affinity copper uptake pump Ctr1 exchanges Cu(I) rapidly with the yeast copper chaperone Atx1: 10(-2) < Kex < 10(+2).     

Transfer of copper between bis(thiosemicarbazone) ligands and intracellular copper-binding proteins. insights into mechanisms of copper uptake and hypoxia selectivity

Bis(thiosemicarbazonato) complexes Cu(II)(Btsc) have attracted interest as promising metallodrugs and, in particular, as copper radiopharmaceuticals. Prototypes Cu(Atsm) and Cu(Gtsm) are membrane-permeable, but their metabolisms in cells are distinctly different: copper that is delivered by Cu(Gtsm) is trapped nonselectively in all cells, whereas copper that is delivered by Cu(Atsm) is retained selectively in hypoxic cells but is "washed out" readily in normal cells. We have studied copper-transfer reactions of these two complexes under various conditions, aiming to model their cellular chemistry. In Me2SO, both complexes exhibited reversible one-electron-reduction processes with Cu(Atsm) being more difficult to reduce than Cu(Gtsm) (E(1/2)'=-0.60 and -0.44 V, respectively, vs AgCl/Ag). Upon introduction of an aqueous buffer into Me2SO, the electrochemical reduction remained chemically reversible for Cu(Atsm) but became irreversible for Cu(Gtsm). However, the estimated difference in their reduction potentials did not change. Chromophoric ligand anions bicinchonate (Bca) and bathocuproine disulfonate (Bcs) were used as Cu(I) indicators to trace the destinations of copper in the reactions and to mimic cellular Cu(I)-binding components ("sinks"). While both BtscH2 ligands have high affinities for Cu(I) (KD in the picomolar range), they cannot compete with Cu(I) sinks such as the copper-binding proteins Atx1 and Ctr1c (or a mimic such as Bcs). In the presence of these proteins, reduction of Cu(II)(Btsc) leads to irreversible transfer of copper to the protein ligands. Endogenous reductants ascorbate and glutathione can reduce Cu(II)(Gtsm) in the presence of such protein ligands but cannot reduce Cu(II)(Atsm). These properties establish a strong correlation between the contrasting cellular retention properties of these complexes and their different reduction potentials. The endogenous reductants in normal cells appear to be able to reduce Cu(II)(Gtsm) but not Cu(II)(Atsm), allowing the latter to be washed out. The more reducing environment of hypoxic cells leads to reduction of Cu(II)(Atsm) and retention of its copper.     

Model peptides provide new insights into the role of histidine residues as potential ligands in human cellular copper acquisition via Ctr1

Cellular acquisition of copper in eukaryotes is primarily accomplished through the Ctr family of copper transport proteins. In both humans and yeast, methionine-rich "Mets" motifs in the amino-terminal extracellular domain of Ctr1 are thought to be responsible for recruitment of copper at the cell surface. Unlike yeast, mammalian Ctr1 also contains extracellular histidine-rich motifs, although a role for these regions in copper uptake has not been explored in detail. Herein, synthetic model peptides containing the first 14 residues of the extracellular domain of human Ctr1 (MDHSHHMGMSYMDS) have been prepared and evaluated for their apparent binding affinity to both Cu(I) and Cu(II). These studies reveal a high affinity Cu(II) binding site (log K = 11.0 ± 0.3 at pH 7.4) at the amino-terminus of the peptide as well as a high affinity Cu(I) site (log K = 10.2 ± 0.2 at pH 7.4) that utilizes adjacent HH residues along with an additional His or Met ligand. These model studies suggest that the histidine domains may play a direct role in copper acquisition from serum copper-binding proteins and in facilitating the reduction of Cu(II) to the active Ctr1 substrate, Cu(I). We tested this hypothesis by expressing a Ctr1 mutant lacking only extracellular histidine residues in Ctr1-knockout mouse embryonic fibroblasts. Results from live cell studies support the hypothesis that extracellular amino-terminal His residues directly participate in the copper transport function of Ctr1.     

CopC protein from Pseudomonas syringae: intermolecular transfer of copper from both the copper(I) and copper(II) sites

The CopC protein from Pseudomonas syringae pathovar tomato is expressed as one of four proteins encoded by the operon CopABCD that is responsible for copper resistance. It is a small soluble molecule (10.5 kDa) with a beta-barrel structure and features two distinct copper binding sites, which are highly specific for Cu(I) (K(D) > or = 10(-)(13)) and Cu(II) (K(D) approximately 10(-)(15)). These dissociation constants were estimated via ligand competition experiments monitored by electronic spectral and fluorescence probes. The chemistries of the two copper sites are interdependent. When the Cu(II) site is empty, the Cu(I) ion is oxidized by air, but when both sites are occupied, the molecule is stable in air. The availability of an unoccupied site of higher affinity induces intermolecular transfer of either Cu(I) or Cu(II) while maintaining free copper ion concentrations in solution at sub-picomolar levels. This intriguing copper chemistry is consistent with the proposed role of CopC as a copper carrier in the oxidizing periplasmic space. These properties would allow it to exchange either Cu(I) or Cu(II) with its putative partners CopA, CopB, and CopD, contrasting with the role of the Cu(I) (only) chaperones found in the reducing cytoplasm.     

A Mets motif peptide found in copper transport proteins selectively binds Cu(I) with methionine-only coordination

Mets motifs, which refer to methionine-rich sequences found in the high-affinity copper transporter Ctr1, also appear in other proteins involved in copper trafficking and homeostasis, including other Ctrs as well as Pco and Cop proteins isolated from copper-resistant bacteria. To understand the coordination chemistry utilized by these proteins, we studied the copper binding properties of a peptide labeled Mets7-PcoC with the sequence Met-Thr-Gly-Met-Lys-Gly-Met-Ser. By comparing this sequence to a series of mutants containing noncoordinating norleucine in place of methionine, we confirm that all three methionine residues are involved in a thioether-only binding site that is selective for Cu(I). Two independent methods, one based on mass spectrometry and one based on rate differences for the copper-catalyzed oxidation of ascorbic acid, provide an effective K(D) of approximately 2.5 microM at pH 4.5 for the 1:1 complex of Mets7-PcoC with Cu(I). These results establish that a relatively simple peptide containing an MX(2)MX(2)M motif is sufficient to bind Cu(I) with an affinity that corresponds well with its proposed biological function of extracellular copper acquisition.     

Hydrothermal syntheses,crystal structures,and properties of two-dimensional homo- and heterometallic cyanide-bridged complexes: [Cu2(CN)2(bpym)] and [Fe(bipy)2(CN)4Cu2] (bpym = 2,2'-bipyrimidine,bipy = 2,2'-bipyridine)

The hydrothermal reaction of K(3)[Fe(CN)(6)], CuCl(2), and 2,2'-bipyridine (bipy) resulted in the formation of a 2D cyanide-bridged heterobimetallic Fe(II)-Cu(I) complex, [Fe(bipy)(2)(CN)(4)Cu(2)], 1. Working in the same conditions, but using 2,2'-bipyrimidine (bpym) instead of bipy and methanol as solvent, we obtained the homometallic Cu(I) complex [Cu(2)(CN)(2)(bpym)](2), 2. The structure of 1 consists of cyanide-bridged Fe(II)-Cu(I) layers, constructed from alternately fused 6 (Fe(2)Cu(4)) and 10 (Fe(2)Cu(8)) metal-membered centrosymmetric rings, in which copper(I) and iron(II) ions exhibit distorted trigonal planar and octahedral cooordination environments, respectively. The formation of 1 can be explained by assuming that, under high pressure and temperature, iron(III) and copper(II) ions are reduced with the simultaneous and/or subsequent substitution of four cyanide ligands by two bipy molecules in the ferricyanide anions. It is interesting to note that 1 is the first cyanide-bridged heterobimetallic complex prepared by solvothermal methods. The structure of 2 consists of neutral 2D honeycomb layers constructed from fused Cu(6)(CN)(4)(bpym)(2) rings, in which copper(I) atoms exhibit distorted tetrahedral geometry. The isolation of 1 and 2, by using K(3)[Fe(CN)(6)] as starting material, demonstrates that hydrothermal chemistry can be used not only to prepare homometallic materials but also to prepare cyanide-bridged bimetallic materials. The temperature dependence of chi(M)T and M?ssbauer measurements for 1 reveal the existence of a high spin <--> low spin equilibrium involving the Fe(II) ions.     

Intermolecular transfer of copper ions from the CopC protein of Pseudomonas syringae. Crystal structures of fully loaded Cu(I)Cu(II) forms

CopC is a small soluble protein expressed in the periplasm of Pseudomonas syringae pathovar tomato as part of its copper resistance response (cop operon). Equilibrium competition reactions confirmed two separated binding sites with high affinities for Cu(I) (10(-7) > or = K(D) > or = 10(-13) M) and Cu(II) (K(D) = 10(-13(1)) M), respectively. While Cu(I)-CopC was converted cleanly by O2 to Cu(II)-CopC, the fully loaded form Cu(I)Cu(II)-CopC was stable in air. Variant forms H1F and H91F exhibited a lower affinity for Cu(II) than does the wild-type protein while variant E27G exhibited a higher affinity. Cation exchange chromatography detected each of the four different types of intermolecular copper transfer reactions possible between wild type and variant forms: Cu(I) site to Cu(II) site; Cu(II) site to Cu(I) site; Cu(I) site to Cu(I) site; Cu(II) site to Cu(II) site. The availability of an unoccupied site of higher affinity induced intermolecular transfer of either Cu(I) or Cu(II) in the presence of O2 while buffering concentrations of cupric ion at sub-picomolar levels. Crystal structures of two crystal forms of wild-type Cu(I)Cu(II)-CopC and of the apo-H91F variant demonstrate that the core structures of the molecules in the three crystal forms are conserved. However, the conformations of the amino terminus (a Cu(II) ligand) and the two copper-binding loops (at each end of the molecule) differ significantly, providing the structural lability needed to allow transfer of copper between partners, with or without change of oxidation state. CopC has the potential to interact directly with each of the four cop proteins coexpressed to the periplasm.     

Multinuclear copper(I) guanidinate complexes

A series of multinuclear Copper(I) guanidinate complexes have been synthesized in a succession of reactions between CuCl and the lithium guanidinate systems Li{L} (L = Me(2)NC((i)PrN)(2) (1a), Me(2)NC(CyN)(2) (1b), Me(2)NC((t)BuN)(2)(1c), and Me(2)NC(DipN)(2) (2d) ((i)Pr = iso-propyl, Cy = cyclohexyl, (t)Bu = tert-butyl, and Dip = 2,6-disopropylphenyl) made in situ, and structurally characterized. The di-copper guanidinates systems with the general formula [Cu(2){L}(2)] (L = {Me(2)NC((i)PrN)(2)} (2a), {Me(2)NC(CyN)(2)} (2b), and {Me(2)NC(DipN)(2)} (2d) differed significantly from related amidinate complexes because of a large torsion of the dimer ring, which in turn is a result of transannular repulsion between adjacent guanidinate substituents. Attempts to synthesis the tert-butyl derivative [Cu(2){Me(2)NC((t)BuN)(2)}(2)] result in the separate formation and isolation of the tri-copper complexes [Cu(3){Me(2)NC((t)BuN)(2)}(2)(μ-NMe(2))] (3c) and [Cu(3){Me(2)NC((t)BuN)(2)}(2)(μ-Cl)] (4c), both of which have been unambiguously characterized by single crystal X-ray diffraction. Closer inspection of the solution state behavior of the lithium salt 1c reveals a previously unobserved equilibrium between 1c and its starting materials, LiNMe(2) and N,N'-di-tert-butyl-carbodiimide, for which activation enthalpy and entropy values of ΔH(?) = 48.2 ± 18 kJ mol(-1) and ΔS(?) = 70.6 ± 6 J/K mol have been calculated using 1D-EXSY NMR spectroscopy to establish temperature dependent rates of exchange between the species in solution. The molecular structures of the lithium complexes 1c and 1d have also been determined and shown to form tetrameric and dimeric complexes respectively held together by Li-N and agostic Li···H-C interactions. The thermal chemistry of the copper complexes have also been assessed by thermogravimetric analysis.     

Perturbation of the Electronic Structure of a Copper(II) ion by a Cu(I)Cl Moiety in a Class I Mixed Valence Copper Complex, Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl)

A new mixed valence copper complex Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl) (2) was obtained from the reaction of CuCl with Cu(II)(Me(5)dien)Cl(2) (1) in acetonitrile. The structures of 1 and 2 have been determined by single-crystal X-ray diffraction analyses. Compound 1 crystallizes in the monoclinic space group P2(1)/n with a = 8.374(5) ?, b = 17.155(3) ?, c = 23.806(5) ?, beta = 94.40(4) degrees, Z = 8, and V = 3398(1) ?(3) while compound 2 crystallizes in orthorhombic space group Pbcn with a = 14.71(1) ?, b = 16.06(2) ?, c = 13.38(1) ?, Z = 8, and V = 3159(5) ?. The Cu(II)(Me(5)dien)Cl(2) unit in both compounds has a similar distorted square-pyramidal geometry. The Cu(I)Cl moiety in 2 is attached to the Cu(II) unit via two bridging chlorine atoms and has a distorted trigonal planar geometry. UV-vis and EPR spectroscopic studies and molecular orbital calculations established the presence of significant perturbation of the Cu(I)Cl unit to the electronic structure of the Cu(II) ion in compound 2.     

Crystal structure and carrier transport properties of a new 3D mixed-valence Cu(I)-Cu(II) coordination polymer including pyrrolidine dithiocarbamate ligand

A novel mixed-valence Cu(i)-Cu(ii) coordination polymer having an infinite three-dimensional (3D) structure, {[Cu(I)(4)Cu(II)(2)Br(4)(Pyr-dtc)(4)]·CHCl(3)}(n) (1) (Pyr-dtc(-) = pyrrolidine dithiocarbamate), has been prepared and structurally characterized via X-ray diffraction. This complex consists of 1D Cu(i)-Br chains and bridging mononuclear copper(ii) units of Cu(II)(Pyr-dtc)(2), which form an infinite 3D network. A magnetic study indicates that this complex includes copper(ii) ions exhibiting a weak antiferromagnetic interaction (θ = -0.086 K) between the unpaired electrons of the copper(ii) ions present in the diamagnetic Cu(i)-Br chains. The carrier transport properties of 1 are investigated using an impedance spectroscopy technique and flash-photolysis time-resolved microwave conductivity measurement (FP-TRMC). The impedance spectroscopy reveals that this complex exhibits intriguing semiconducting properties at a small activation energy (E(a) = 0.29 eV (bulk)). The sum of the mobilities of the negative and positive carriers estimated via FP-TRMC is Σμ～ 0.4 cm(2) V(-1) s(-1).     

Architecture dependence on the steric constrains of the ligand in cyano-bridged copper(I) and copper(II)-copper(I) mixed-valence polymer compounds containing diamines: crystal structures and spectroscopic and magnetic properties

A family of cyano-bridged copper(II)-copper(I) mixed-valence polymers containing diamine ligands of formula [Cu(pn)(2)][Cu(2)(CN)(4)] (1, pn = 1,2-propanediamine), [Cu(2)(CN)(3)(dmen)] (2, dmen = N,N-dimethylethylenediamine), and [Cu(3)(CN)(4)(tmen)] (3, tmen = N,N,N',N'-tetramethylethylenediamine) have been prepared with the aim of analyzing how their architecture may be affected by steric constraints imposed by the diamine ligands. In the absence of diamine and with use of the voluminous NEt(4)(+) cation, the copper(I) polymer [NEt(4)][Cu(2)(CN)(3)] (4) forms. The structure of 1 consists of a three-dimensional diamond-related anionic framework host, [Cu(2)(CN)(4)](2-), and enclathrated [Cu(pn)(2)](2+) cations. The structure of 2 is made of neutral corrugated sheets constructed from fused 18-member nonplanar rings, which contain three equivalent copper(I) and three equivalent copper(II) centers bridged by cyanide groups in an alternative form. The 3D structure of 3 consists of interconnected stair-like double chains built from fused 18-member rings, which adopt a chairlike conformation. Each ring is constructed from two distorted trigonal planar Cu(I) centers, two bent seemingly two-coordinated Cu(I) centers, and two pentacoordinated Cu(II) atoms. The structure 4 is made of planar anionic layers [Cu(2)(CN)(3)](n)(n-) lying on mirror planes and NEt(4)(+) cations intercalated between the anionic layers. From the X-ray structural results and calculations based upon DFT theory some conclusions are drawn on the structure-steric factors correlation in these compounds. Compound 1 exhibits very weak luminescence at 77 K with a maximum in the emission spectrum at 520 nm, whereas compound 4 shows an intense luminescence at room temperature with a maximum in the emission spectrum at 371 nm. Polymers 2 and 3 exhibit weak antiferromagnetic magnetic exchange interactions with J = -0.065(3) and -2.739(5) cm(-1), respectively. This behavior have been justified on the basis of the sum of two contributions: one arising from the pure ground-state configuration and the other one from the charge-transfer configuration Cu(I)-CN-Cu(II)-CN-Cu(II) that mixes with the ground-state configuration.     

Binuclear copper(II) oxidation products from copper(I) complexes with tridentate ligands. Magnetostructural characterization

The bis-pyridine tridentate ligands (6-R-2-pyridylmethyl)-(2-pyridylmethyl) benzylamine (RDPMA, where R = CH(3), CF(3)), (6-R-2-pyridylmethyl)-(2-pyridylethyl) benzylamine (RPMPEA, where R = CH(3), CF(3)), and the bidentate ligand di-benzyl-(6-methyl-2-pyridylmethyl)amine (BiBzMePMA) have been synthesized and their copper(I) complexes oxidized in a methanol solution to afford self-assembled bis-micro-methoxo-binuclear copper(II) complexes (1, 2, 4, 6) or hydroxo- binuclear copper(II) complexes (3). Oxidation of the nonsubstituted DPMA (R = H) in dichloromethane gives a chloride-bridged complex (5). The crystal structures for [Cu(MeDPMA)(MeO)](2)(ClO(4))(2) (1), [Cu(RPMPEA)(MeO)](2)(ClO(4))(2) (for 2, R= Me, and for 4, R = CF(3)), [Cu(BiBzMePMA)(MeO)](2)(ClO(4))(2) (6), [Cu(FDPMA)(OH)](2)(ClO(4))(2) (3), and [Cu(DPMA)(Cl)](2)(ClO(4))(2) (5) have been determined, and their variable-temperature magnetic susceptibility has been measured in the temperature range of 10-300 K. The copper coordination geometries are best described as square pyramidal, except for 6, which is square planar, because of the lack of one pyridine ring in the bidentate ligand. In 1-4 and 6, the basal plane is formed by two pyridine N atoms and two O atoms from the bridging methoxo or hydroxo groups, whereas in 5, the bridging Cl atoms occupy axial-equatorial sites. Magnetic susceptibility measurements show that the Cu atoms are strongly coupled antiferromagnetically in the bis-methoxo complexes 1, 2, 4, and 6, with -2J > 600 cm(-)(1), whereas for the hydroxo complex 3, -2J = 195 cm(-)(1) and the chloride-bridged complex 5 shows a weak ferromagnetic coupling, with 2J = 21 cm(-)(1) (2J is an indicator of the magnetic interaction between the Cu centers).     

Crystal structure of the copper(I) complex Cu(py-Clan)(PPh3)I

Journal of Structural Chemistry - A mixed ligand copper(I) Schiff base complex [Cu(py-Clan)(PPh3)I], where py-Clan = = 4-chlorophenylpyridine-2-ylmethyleneamine, is synthesized and structurally...     

2-Benzoylpyridine thiosemicarbazone as a novel reagent for the single pot synthesis of dinuclear Cu(I)-Cu(II) complexes: formation of stable copper(II)-iodide bonds

2-Benzoylpyridine thiosemicarbazone {R(1)R(2)C(2)=N(2)·N(3)H-C(1)(=S)-N(4)H(2), R(1) = py-N(1), R(2) = Ph; Hbpytsc} with copper(I) iodide in acetonitrile-dichloromethane mixture has formed stable Cu(II)-I bonds in a dark green Cu(II) iodo-bridged dimer, [Cu(2)(II)(μ-I)(2)(η(3)-N(1),N(2),S-bpytsc)(2)] 1. Copper(I) bromide also formed similar Cu(II)-Br bonds in a dark green Cu(II) bromo-bridged dimer, [Cu(2)(II)(μ-Br)(2)(η(3)-N(1),N(2),S-bpytsc)(2)] 3. The formation of dimers 1 and 3 appears to be due to a proton coupled electron transfer (PCET) process wherein copper(I) loses an electron to form copper(II), and this is accompanied by a loss of -N(3)H proton of Hbpytsc ligand resulting in the formation of anionic bpytsc(-). When copper(I) iodide was reacted with triphenylphosphine (PPh(3)) in acetonitrile followed by the addition of 2-benzoylpyridine thiosemicarbazone in dichloromethane (Cu?:?PPh(3)?:?Hbpytsc in the molar ratio 1:1:1), both Cu(II) dimer 1 and an orange Cu(I) sulfur-bridged dimer, [Cu(2)(I)I(2)(μ-S-Hbpytsc)(2)(PPh(3))(2)] 2 were formed. Copper(I) bromide with PPh(3) and Hbpytsc also formed Cu(II) dimer 3 and an orange Cu(I) sulfur-bridged dimer, [Cu(2)(I)Br(2)(μ-S-Hbpytsc)(2)(PPh(3))(2)] 4. While complexes 2 and 4 exist as sulfur-bridged Cu(I) dimers, 1 and 3 are halogen-bridged. The central Cu(2)S(2) cores of 2 and 4 as well as Cu(2)X(2) of 1 (X = I) and 3 (X = Br) are parallelograms. One set of Cu(II)-I and Cu(II)-Br bonds are short, while the second set is very long {1, Cu-I, 2.565(1), 3.313(1) ?; 3, Cu-Br, 2.391(1), 3.111(1) ?}. The Cu···Cu separations are long in all four complexes {1, 4.126(1); 2, 3.857(1); 3, 3.227(1); 4, 3.285(1) ?}, more than twice the van der Waals radius of a Cu atom, 2.80 ?. The pyridyl group appears to be necessary for stabilizing the Cu(II)-I bond, as this group can accept π-electrons from the metal.     

Hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyanions and polymeric copper(I) complexes

Four hybrid inorganic-metalorganic compounds containing copper(II)-monosubstituted Keggin polyoxotungstates, K3[Cu(I)(4,4'-bpy)]3[SiW11Cu(II)O39].11H2O (1), (paraquat)3[SiW11Cu(II)O39].6H2O (2; paraquat = N,N'-dimethyl-4,4'-bipyridinium), K3[Cu(I)(4,4'-bpy)]3[GeW11Cu(II)O39].11H2O (3), and Na2[Cu(I)(4,4'-bpy)]3[PW11Cu(II)O39(H2O)].4H2O (4), have been synthesized under autogenous pressure hydrothermal conditions and characterized by elemental analysis and infrared spectroscopy (FT-IR). The crystal structures of 1, 2, and 4 have been established by single-crystal X-ray diffraction. The crystal packings are characterized by the presence of monodimensional extended entities: either the polymeric polyanion [SiW11CuO39]n(6n-) (2), the cationic [Cu(4,4'-bpy)]n(n+) chain (4), or both simultaneously as in compound 1, where the inorganic and metalorganic sublattices are mutually perpendicular. To asses the influence of packing in the copper(I) complex structural diversity found in compounds 1 and 4, a search in the CSD database has been performed and the resulting geometrical features have been analyzed and compared with experimental crystallographic data and DFT calculations.     

Complexes of N-thiophosphorylthioureas (HL) with copper(I). Crystal structures of [Cu3L3] and [Cu(PPh3)2L] chelates

Reaction of the potassium salts of N-thiophosphorylated thioureas of common formula RC(S)NHP(S)(OiPr)(2) [R = morpholin-N-yl (HL(a)), piperidin-N-yl (HL(b)), NH(2) (HL(c)), PhCH(2)NH (HL(d))] with Cu(PPh(3))(3)I in aqueous EtOH/CH(2)Cl(2) leads to mononuclear [Cu(PPh(3))(2)L-S,S'] complexes. Using copper(i) iodide instead of Cu(PPh(3))(3)I, polynuclear complexes [Cu(n)(L-S,S')(n)] were obtained. The structures of these compounds were investigated by ES-MS, elemental analyses, 1H and 31P NMR in solution, IR and 31P solid-state MAS NMR spectroscopy. The crystal structures of [Cu(3)L(3)(a)] and [Cu(PPh(3))(2)L(b)] were determined by single-crystal X-ray diffraction.     

Synthesis,structure and characterization of binuclear copper(I) complexes

Binuclear copper(I) complexes [Cu(dppm)(NO3)]2 (1), dppm=Ph2PCH2PPh2, [Cu(dppm)(2,9-Me2Phen)]2(NO3)2 (2), [Cu(dppm)(I)]2 (3) and [Cu(dppm)(py)]2(NO3)2 (4), (py=pyridine) have been synthesized by ligand reduction of cupric nitrate with dppm in EtOH and characterized by elemental analyses, molecular weight determination, t.g.a., 31P-n.m.r spectra; their electronic conductivities and c.v. waves have also been measured. The results show that dppm coordinates as a bridging bidentate ligand to the CuI atoms, and that NO3 behaves as a monodentate ligand or free ion in the newly prepared complexes.     

Photoluminescent copper(I) complexes with amido-triazolato ligands

A series of heteroleptic copper(I) complexes incorporating amido-triazole and diphosphine ligands, [Cu(I)(N-phenyl-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (1), [Cu(I)(N-(4-methylphenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (2), [Cu(I)(N-(4-methoxyphenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (3), [Cu(I)(N-(4-chlorophenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (4), [Cu(I)(2,6-dimethyl-N-[2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl]aniline)(dppb)] (5), [Cu(I)(2,6-dimethyl-N-[2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl]aniline)(dppb)] (6), (dppb = 1,2-bis(diphenylphosphino)benzene), have been prepared. The complexes adopt a distorted tetrahedral geometry in the solid state with the amido-triazole ligand forming a six-member ring with the Cu(I) ion. The complexes exhibit long-lived photoluminescence with colors ranging from yellow to red-orange in the solid state, in frozen glass at 77 K, and in fluid solution with modest quantum yields of up to 0.022. Electrochemically, complexes 1-4 show irreversible oxidation waves while 5 and 6 are characterized by quasi-reversible oxidations as determined by cyclic voltammetry. For 1-4, the emission energy and oxidation potential are found to vary linearly with the Hammett parameter σ(p) of the substituent in the para position of the amido ligand, while in 5 and 6, large differences in emission are observed because of the nature of N3 substitution in the triazole ring. Density functional theory calculations have been performed on the singlet ground states (S(o)) of all complexes at the BP86/6-31G(d) level to assist in assignment of the excited states. On the basis of both experimental and computational results, we have assigned the excited states as intraligand + metal-to-ligand charge transfer (3)(ILCT+MLCT) or ligand-to-ligand charge transfer mixed with MLCT (3)(MLCT +LLCT) in these complexes.     

Syntheses and structures of copper(I) complexes based on Cu(n)X(n) (X = Br and I; n = 1, 2 and 4) units and bis(pyridyl) ligands with longer flexible spacer

Self-assembly of four bis(pyridyl) ligands with longer flexible spacer: 1,4-bis(3-pyridylaminomethyl)benzene (L1), 1,4-bis(2-pyridylaminomethyl)benzene (L2), 1,3-bis(3-pyridylaminomethyl)benzene (L3) and 1,3-bis(2-pyridylaminomethyl)benzene (L4), and CuX (X = Br and I) leads to the formation of eight [Cu(n)X(n)]-based (X = Br and I; n = 1, 2, and 4) complexes, [Cu(2)I(2)L1(PPh(3))(4)] (1), [Cu(4)Cl(2)Br(2)(L4)(2)(PPh(3))(6)]·(CH(3)CN)(2) (2), [Cu(2)I(2)(L3)(2)] (3), {[Cu(2)Br(2)L2(PPh(3))(2)]·(CH(2)Cl(2))(2)}(n) (4), [CuIL1](n)·nCH(2)Cl(2) (5), [CuIL1](n) (6), [CuIL4](n) (7) and [Cu(2)I(2)L4](n) (8), which have been synthesized and characterized by elemental analysis, IR, TG, powder and single-crystal X-ray diffraction. Structural analyses show that the eight complexes possess an increasing dimensionality from 0D (1-3) to 1D (4) to 2D (5-8), in which 1 and 2 contain a CuX unit, 2-7 contain a Cu(2)X(2) unit and 8 contains a Cu(4)X(4) unit. Such evolvement indicates that the conformation of flexible bis(pyridyl) ligands and the participation of triphenylphosphine (PPh(3)) as a second ligand take an essential role in the framework formation of the Cu(i) complexes. Moreover, a pair of symmetry-related L3 ligands in complex 3 coordinate to the rhomboid Cu(2)I(2) dimer to form "handcuff-shaped" dinuclear structures, which are further joined together through intermolecular N-HI hydrogen bonds to furnish a 2D (4,4) layer. Although complexes 5 and 6 exhibit a similar 2D (4,4) layer constructed from L1 ligand bridging [Cu(2)I(2)](n) units, the different packing fashion of the layers leads to the formation of 3D porous frameworks of 5 and dense 3D frameworks of 6. The "twisted-boat" conformation of the Cu(4)I(4) tetramer unit in complex 8 has not been reported so far.     

Construction of a novel copper(I) chain polymer of hexanuclear Cu6(2-SC5H4NH)6I6 cores with a new (mu 3-S) mode of bonding of pyridine-2-thione and of an unusual triangular Cu3I3(dppe)3(2-SC5H4NH) cluster

The reactions of copper(I) iodide with pyridine-2-thione (2-SC(5)H(4)NH) in the presence of a series of diphosphane ligands, Ph(2)P[bond]X[bond]Ph(2)P [X = [bond](CH(2))(m)[bond], m = 1(dppm), 2 (dppe), 3 (dppp), 4 (dppb); [bond]CH[double bond]CH[bond] (dppen)], yielded an iodo-bridged hexanuclear Cu(I) linear polymer, [Cu(6)(mu(3)-SC(5)H(4)NH)(4)(mu(2)-SC(5)H(4)NH)(2)(I(4))(mu-I)(2)-](n).2nCH(3)CN (1). A similar reaction with 1,2-bis(diphenylphosphino)ethane (dppe) and 2-SC(5)H(4)NH yielded a triangular cluster, Cu(3)I(3)(dppe)(3)(2-SC(5)H(4)NH), 2. In the chain polymer 1, three Cu(I) iodide and three 2-SC(5)H(4)NH ligands combined via bridging S donor atoms to form a boat-shaped trinuclear Cu(3)S(3)I(3) core, and two such cores combined in an inverse manner via four S-donor atoms (mu(3)-S) to form a centrosymmetric hexanuclear repeat unit, Cu(6)S(6)I(4)(mu-I)(2-), which finally formed the iodo-bridged infinite linear chain polymer 1. Linear chains are separated by the nonbonded acetonitrile molecules. Polymer 1 is the first such example of a linear chain formed by the hexanuclear Cu(6)S(6)I(6) core in copper chemistry as well as in metal-heterocyclic thioamide chemistry. In addition, it has the first mu(3)-S mode of neutral pyridine-2-thione ever reported. In the moiety Cu(3)I(3)(dppe)(3) of 2, two copper(I) centers are bridged by the iodide ligands forming a Cu(mu-I)(2)Cu core, while a third copper(I) center is terminally bonded to another iodide ligand. Polymer 2 is also rare, and the first triangular cluster of Cu(I) with an heterocyclic thioamide.