CuII Cations Research Articles

Synthesis, Characterization and Identification of Mononuclear Transition Metals Complexes 1, 3-Bis-((5-methyl-1H-Imidazol-4-yl) Methyleneamino) Propan-2-ol Ligand

The ligand 1,3-bis-((5-methyl-1H-imidazol-4-yl)methyleneamino)propan-2-ol (H3L) derived from 1,3-diaminopropan-2-ol and 5-methyl-1H-imidazole-4-carbaldehyde has been synthetized and used to prepare five complexes in which the ligand acts in tetradentate fashion. Complexes formulated as [Mn(H3L)(H2O)2].2SCN (1), [(Co(H3L)].2SCN (2), [(Ni(H3L)].2SCN (3), [(Cu(H3L)(NO3)].(NO3).2H2O (4), and [(Zn(H3L)].2SCN (5) were synthesized by mixing an equimolar amount of an methanol solution containing the appropriate nitrate salt and KSCN, in 1:2 ratio, in the case of 1, 2, 3 and 5 and an ethanol solution containing the appropriate ligand H3L. The complex 4 has been synthetized in the absence of KSCN. In all the complexes the ligand acts in its neutral form and in tetradentate fashion, its hydroxy group remaining free and non-deprotonated. The ligand is coordinated to metal ion through two azomethine nitrogen atoms and two pyrazole sp2 nitrogen atoms. The complexes are characterized by elemental analysis, conductance and room temperature magnetic moments measurements, UV–Vis and IR spectroscopic studies. The structure of the copper(II) complex 4 is confirmed by X-ray diffraction. 4 crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 8.5459 (3) Å, b = 10.9177 (3) Å, c = 22.4562 (6) Å, b = 96.954 (3)°, V = 2079.79 (11) Å3, Z = 4, R1 = 0.050 and wR2 = 0.131. The CuII cation in N4O inner is situated in a distorted square pyramidal environment.

Poly[[[μ3-3-(2-carboxyl-atophen-yl)propionato][μ2-N,N'-(ethane-1,2-di-yl)bis-(pyridine-4-carbox-amide)]copper(II)] monohydrate], a layered coordination polymer with (4,4) topology.

In the title compound, {[Cu(C10H8O4)(C14H14N4O2)]·H2O}n, the CuII cations are coordinated in a square-pyramidal fashion, with trans pyridyl-N donor atoms from two N-(2-(pyridin-3-yl-amino)-eth-yl)isonicotinamide (pein) ligands in the basal plane. The other three coordination sites are taken up by carboxyl-ate O-atom donors from three different 3-(2-carb-oxy-phen-yl)propionate (cpp) ligands. The central ethyl-enedi-amine segments of the pein ligands are disordered equally over two sets of positions. {Cu2O2} rhomboid clusters are connected into [Cu(cpp)(pein)]n (4,4) coordination polymer grids by the full span of the cpp and pein ligands. Individual layer motifs stack in an AAA pattern along the a axis by means of inter-layer hydrogen-bonding inter-actions.

Poly[[bis-[μ4-3-(2-carboxyl-atophen-yl)propionato]{N-[2-(pyridine-3-amido)-eth-yl]nicotinamide}-dicopper(II)] penta-hydrate

In the title compound, {[Cu2(C10H8O4)2(C14H14N4O2)]·5H2O}n, the CuII cations are coordinated in a square-pyramidal fashion, with four 3-(2-carb-oxy-phen-yl)propionate (cpp) carboxyl-ate O-atom donors in the basal plane, along with an N-atom donor from a N-[2-(pyridin-3-yl-amino)-eth-yl]nicotinamide (pen) ligand in the apical position. [Cu2(cpp)2]n coordination polymer layer motifs with embedded {Cu2(OCO)4} paddlewheel clusters are thereby constructed. These layer motifs are connected into a three-dimensional [Cu2(cpp)2(pen)]n coordination polymer network by tethering pen ligands. Treating the {Cu2(OCO)4 paddelwheel clusters as 6-connected nodes reveals an underlying cross-pillared self-penetrated rob network with 48668 topology. The water mol-ecules of crystallization are held to the coordination polymer network by N-H⋯O and O-H⋯O hydrogen-bonding patterns.

Synthesis, crystal structure and thermal properties of di-μ-iodido-bis-[bis-(2-chloro-pyrazine-κN)copper(I)

Reaction of copper(I) iodide in pure 2-chloro-pyrazine leads to the formation of a few crystals of the title compound, [Cu2I2(C4H3ClN2)4] or (CuI)2(2-chloro-pyrazine)4, which was characterized by single-crystal X-ray diffraction. In its crystal structure, the CuI cations are each tetra-hedrally coordinated by two iodide anions and two 2-chloro-pyrazine ligands and are linked into binuclear complexes consisting of (CuI)2 rings located on centers of inversion. PXRD investigations of a few crystals obtained from the suspension indicate that the title compound is contaminated with a small amount of the 2-chloro-pyrazine-deficient compound CuI(2-chloro-pyrazine) already reported in the literature. PXRD investigations prove that the title compound immediately decomposes at room temperature into CuI(2-chloro-pyrazine) and this might be the reason why no pure samples can be obtained. TDA-TG-MS investigations shows two mass losses, the first of which corresponds to the formation of CuI(2-chloro-pyrazine), whereas in the second mass loss CuI is formed.

A Rigid Linker for Site-Selective Coordination of Transition Metal Cations: Combining an Acetylacetone with a Caged Phosphine

The combination of a soft phosphorus and a hard oxygen donor in the new ligand HacacTRIP leads to excellent site selectivity for the coordination of two different metal cations of matching Pearson character. The deprotonation step required for coordinating the acetylacetone oxygen donor further increases the selectivity. In contrast to most phosphines, the use of the caged phosphatriptycene motif enables a rigid and directional orientation of the phosphorus binding site which is required to form stable coordination network structures. In addition to the synthesis of HacacTRIP, we present its selective coordination. The deprotonated acetylacetone was selectively bound to CuII and FeIII. The solid state structure of the former displays a rare axial coordination of chloroform molecules. The phosphorus donor was selectively coordinated to the monovalent coinage metal cations CuI, AgI, and AuI. The CuI and AgI complexes represent the first examples in which a phosphatriptycene is bound to these metal cations. Heterometallic coordination compounds were characterized with combinations of these two groups. They comprise an oligonuclear CuI/CuII mixed-valence compound in which iodide binds to both CuI and CuII cations and a complex in which acacTRIP- bridges CuII and AuI. In addition to these discrete aggregates, the ligand has been used to link FeIII and AgI into a 2D coordination polymer with unprecedented trigonal planar coordination of three bulky phosphatriptycenes to a cation and resulting honeycomb topology. Its almost regular hexagons underline the desired rigidity of the ditopic acacTRIP- ligand.

Crystal structure of a copper–mefenamate complex solvated with diglyme and water

In the copper–mefenamate complex tetrakis[μ-2-(2,3-dimethylanilino)benzoato-κ2 O:O′]bis[aquacopper(II)]–1-methoxy-2-(2-methoxyethoxy)ethane (1/2), [Cu2(C15H14NO2)4(H2O)2]·2C6H14O3, the asymmetric unit comprises a CuII cation coordinated to two mefenamate ligands solvated with a water molecule and a diglyme molecule. The complex adopts a paddlewheel motif and is compared to structural analogues crystallized with dimethylformamide and dimethyl sulfoxide.

5‐Amino‐2‐isopropenyltetrazole and its Cupric Chloride Complex: Synthesis, Structure and Magnetism

AbstractA new tetrazole ligand, 5‐amino‐2‐isopropenyltetrazole, was prepared by regioselective alkylation of 5‐aminotetrazole with allyl bromide in sulfuric acid followed by dehydrobromination of intermediate 5‐amino‐2‐(1‐bromopropan‐2‐yl)tetrazole. 5‐Amino‐2‐isopropenyltetrazole (L) was found to react with copper(II) chloride to generate complex [CuL2Cl2]n. The ligand and its complex were characterized by single crystal X‐ray and thermal analyses. Complex [CuL2Cl2]n presents 1D coordination polymer, formed at the expense of double chlorido bridges between neighbouring octahedral coordinated CuII cations. Tetrazole ligand acts as monodentate ligand coordinated by CuII cations via the heteroring N4 atoms only. Magnetic studies revealed that the copper(II) ions were weakly antiferromagnetically coupled. Natural bond orbital analysis was performed to explain the structural peculiarities of the ligand. Its basicity and the relative stability of the protonated forms were investigated using MO calculations.

Coordination of a Pyrazole Functionalized Acetylacetone to the Coinage Metal Cations: An Unexpected Packing Similarity and a Trinuclear CuII/AuI Complex

The heteroditopic molecule HacacMePz combines a Pearson hard acetylacetone donor site with a softer trimethylpyrazole and shows site selectivity towards the coinage metal cations. The coordination of the N donor function was achieved towards AgI and AuI, leading to the salt [Ag(HacacMePz)2]PF6 (1) and the neutral complex [AuCl(HacacMePz)] (2). In either case, linear coordination about the coinage metal cation is observed. Interestingly, both complexes crystallize in space group Pbca with similar cell parameters. The two solids do not qualify as isostructural, albeit being closely related in real and reciprocal space. To probe the ligand’s ability for the envisaged synthesis of bimetallic coordination polymers, the mixed-metal CuII/AuI complex [Cu(acacMePzAuCl)2] (3) was obtained. In this mixed-metal oligomer, the central CuII cation adopts a square planar coordination environment with two O,O′-coordinated acacMePz− ligands, whose softer N donor sites are saturated with a AuCl moiety.

Tetra-nuclear copper(II) complex of 2-hydroxy-N,N'-bis-[1-(2-hy-droxy-phen-yl)ethyl-idene]-propane-1,3-di-amine.

The title mol-ecular structure, namely, (μ3-acetato)(μ2-acetato)-bis-(μ3-1,3-bis-{[1-(2-oxidophen-yl)ethyl-idene]amino}-propan-2-olato)tetra-copper(II) monohydrate, [Cu4(C19H19N2O3)2(CH3CO2)2]·H2O, corresponds to a non-symmetric tetra-nuclear copper complex. The complex exhibits one ligand mol-ecule that connects two copper CuII metal centres via its ethano-lato oxygen anion acting in a μ2-mode and one ligand mol-ecule that connects three copper CuII metal centres via its ethano-lato oxygen anion acting in a μ3-mode. One bridging acetate group acting in an η1:η1-μ2-mode connects two copper(II) ions while another bridging acetate group connects three copper(II) ions in an η1:-η2-μ3-mode. A chair-like Cu3O3 structure is generated in which the two CuO4N units are connected by one μ2-O ethano-late oxygen atom. These two units are connected respectively to the CuO3N unit via one μ3-O ethano-late oxygen atom and one μ2-O atom from an acetate group. The μ3-O atom also connects one of the CuO4N units and the CuO3N unit to another CuO3N unit, which is out of the chair-like structure. Each of the two penta-coordinated CuII cations has a distorted NO4 square-pyramidal environment. The geometry of each of the two CuNO3 units is best described as a slightly square-planar environment. A series of intra-molecular O-H⋯O hydrogen bonds is observed. In the crystal, the units are connected by inter-molecular C-H⋯O and O-H⋯O hydrogen bonds, thus forming sheets parallel to the ac plane.

Self-association synthesis with ortho-vanillin to promote mono- and heptanuclear complexes and their evaluation as antioxidant agents

This study describes the synthesis, crystal structure, antioxidant activity, and molecular modeling calculations for two CuII complexes obtained from the condensation of ortho-vanillin with furfurylamine. Both complexes catalyzed superoxide dismutation and were evaluated and quantified by nitro blue tetrazolium photoreduction, efficiently demonstrating McCord-Fridovich constant values from 5.50 to 2.87 × 106 (M−1s−1) in the 1.3–1.4 µM range and an aqueous solution of pH 7.8. Despite an unusual arrangement containing seven CuII cations obtained by self-association processes, the heptamer, proportionally speaking, did not show multiplicative activity as initially expected. This situation was also evaluated using molecular docking.

Crystal structure, Hirshfeld surface analysis and DFT studies of tetra-kis-(μ-3-nitro-benzoato-κ2 O 1:O 1')bis-[(N,N-di-methyl-formamide-κO)copper(II)] di-methyl-formamide disolvate.

The title compound, [Cu2(C7H4NO4)4(C3H7NO)2]·(C3H7NO)2, is a binuclear copper(II) complex located on an inversion center midway between the two copper(II) cations. The asymmetric unit consists of one CuII cation, two 3-nitro-benzoato ligands, and two di-methyl-formamide (DMF) mol-ecules, one of which coordinates to the CuII cation and one is a solvate mol-ecule. The carboxyl-ate groups of the ligands bridge two CuII cations with a Cu-Cu distance of 2.6554 (6) Å, completing a distorted octa-hedral O5Cu coordination environment. The dihedral angles between the carboxyl-ate and the aromatic ring planes of the two independent ligands are different from one another, viz. 5.2 (3) and 23.9 (3)°. The three-dimensional structure is consolidated by weak C-H⋯O inter-actions and stabilized by π-π stacking inter-actions between the aromatic rings. The complex and the free ligand were further characterized by Fourier-transform infrared spectroscopy (FT-IR), and the energies of the frontier mol-ecular orbitals of the complex were determined by DFT calculations at the B3LYP/def2-TZVP level of theory.

Organic Long Persistent Luminescence Through In Situ Generation of Cuprous(I) Ion Pairs in Ionic Solids

Recent development of most organic long persistent luminescence (OLPL) systems employed binary or tertiary doping. However, the design strategies towards OLPL materials with hour-long afterglow duration are still quite limited. Here, we propose a novel OLPL system through melt-casting method with 0.1 mol % of CuI complexes: 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl BINAP-CuX (X=Cl, Br and I) doped into the triphenylphosphine (TPP) host. The charge separation was initiated prior to excitation through host coordination with CuI complexes, resulting in semi-free halogen ions and in situ generated CuI cations, which forms TPP + BINAP-CuX ionic pairs and subsequently ionic solids. The OLPL lifetime can be readily modulated by different halogen atoms and the afterglow can last up to more than 3 hours perceivable to human eyes. This is a rare example of OLPL initiated through host-guest coordination that could potentially expand the definition of OLPL systems and design strategies.

Organic Long Persistent Luminescence Through In Situ Generation of Cuprous(I) Ion Pairs in Ionic Solids

AbstractRecent development of most organic long persistent luminescence (OLPL) systems employed binary or tertiary doping. However, the design strategies towards OLPL materials with hour‐long afterglow duration are still quite limited. Here, we propose a novel OLPL system through melt‐casting method with 0.1 mol % of CuI complexes: 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl BINAP‐CuX (X=Cl, Br and I) doped into the triphenylphosphine (TPP) host. The charge separation was initiated prior to excitation through host coordination with CuI complexes, resulting in semi‐free halogen ions and in situ generated CuI cations, which forms TPP + BINAP‐CuX ionic pairs and subsequently ionic solids. The OLPL lifetime can be readily modulated by different halogen atoms and the afterglow can last up to more than 3 hours perceivable to human eyes. This is a rare example of OLPL initiated through host‐guest coordination that could potentially expand the definition of OLPL systems and design strategies.

Self-assembling of three rare structurally various homomultinuclear CuII complexes derived from a bis(salamo)-based multioxime ligand

A family of rare structurally different homometal multinuclear CuII bis(salamo)-based complexes, [Cu4(L)2(MeOH)2](ClO4)2·2MeOH (1), [Cu4(L)2(EtOH)2](NO3)2·2EtOH (2) and [Cu2(HL)(EtOH)Br2]·CHCl3 (3), has been successfully synthesized by the reactions of cupric salts with a bis(salamo)-based multidentate chelate ligand (H3 L). The salamo-based ligand [R-CH=N—O—(CH2) n —O—N=CH—R] is a new type of salen-based analog. Complexes (1) and (2) are isostructural structures, and crystallize in monoclinic space group P21/n with centrosymmetric spiral structures, where the main structures contain two fully deprotonated ligand (L)3− units, a charged tetranuclear CuII folding center and two coordinated solvent molecules. Complex (3) crystallizes in monoclinic space group Cc and consists of two CuII cations, one incompletely deprotonated ligand (HL)2− unit and one coordinated ethanol molecule, and forms a novel homo-binuclear CuII complex structure due to Br− counter anions. Complexes (1)–(3) have zero-dimensional cluster-based structures and are further assembled into three-dimensional frameworks via intermolecular interactions. Because of the different solvents and counter anions which have a significant influence on the structures of complexes (1)–(3), the interactions were quantitatively evaluated by Hirshfeld surfaces analyses. Complexes (1)–(3) have been characterized by elemental analyses, IR spectra, UV–vis spectra and X-ray crystallography analyses. In addition, fluorescence properties are evaluated and DFT calculations are performed.

Hexanuclear copper(II) complex of 2-hy-droxy-N,N'-bis-[1-(2-hy-droxy-phen-yl)ethyl-idene]propane-1,3-di-amine incorporating an open-cubane core.

The title mol-ecular structure, namely, di-aqua-tris-(μ3-1,3-bis-{[1-(2-oxidophen-yl)ethyl-idene]amino}-propan-2-olato)-μ3-hydroxido-dinitrato-hexa-copper(II) ethanol tris-olvate, [Cu6(C19H19N2O3)3(NO3)2(OH)(H2O)2]·3C2H5OH, corres-ponds to a non-symmetric hexa-nuclear copper complex. The complex exhibits one core in which three CuII metal centres are mutually inter-connected, two by two, via three phenolato oxygen anions acting in a μ2-mode. These three copper cations are inter-connected in a μ3-mode by one hydroxyl group. An open-cube structure is generated in which each of the CuII cations of the three CuO4N units is connected by two μ2-O anions from phenolate groups and one μ3-O atom from a hy-droxy anion. Each of the three penta-coordinated CuII cations situated in the open-cube unit has a distorted NO4 square-pyramidal environment. Each of these three CuII centres is inter-connected with another CuII cation via one enolate O atom in μ2-mode, yielding one CuNO4 unit and two CuNO3 units. The penta-coordinated CuII atom has a distorted square-pyramidal environment while the two tetra-coordinated copper(II) cations are situated in a square-planar environment. A series of intra-molecular O-H⋯O hydrogen bonds are observed. In the crystal, the units are connected two by two by inter-molecular C-H⋯O and O-H⋯O hydrogen bonds, thus forming sheets parallel to the ac plane.

Metal-Organic Nanocapsules with Functionalized s-Heptazine Ligands.

A metalloorganic capsule was synthesized where the ligand is a derivative of heptazine with three carboxylic groups that are coordinated to CuII cations, forming paddle-wheel motifs. Each nanocapsule is neutral, with 12 CuII centers and 8 ligands adopting a rhombicuboctahedron shape. It has almost 3 nm diameter, and the main intermolecular interactions in the solid are π··· π stacking between the C6N7 heptazine moieties. The nanocapsules can form monolayers deposited on graphite as observed by atomic force microscopy, which confirms their stability in solution.

Microwave synthesis conditions dependent catalytic performance of hydrothermally aged CuII-SSZ-13 for NH3-SCR of NO

To simplify the complicated synthetic techniques so that getting CuII-SSZ-13 zeolites with ideal structures and CuII cations distribution, and to interrogate CuII cations dynamics dependent NH3 mediated performance of selective catalytic reduction (NH3-SCR) of NO and hydrothermal stability, a microwave-assisted hydrothermal synthesis route was performed to prepare CuII exchanged SSZ-13 zeolite catalysts. The effects of synthetic temperature and time on the structure of SSZ-13 zeolite and NH3-SCR performance are clarified. The types and numbers of CuII species of fresh and hydrothermal aged samples were precisely explored. The NH3-SCR activity, N2 selectivity of fresh and aged CuII-SSZ-13 zeolites synthesized by different conditions are evaluated, respectively. Experimental characterizations demonstrate that the CuII-SSZ-13 zeolites can be synthesized with short crystallization time assisted with microwave treatment. The microwave synthesis temperature and time can affect the nucleation and growth process of SSZ-13 and thus resulting in SSZ-13 with different framework structures and various affinity to CuII ions. When the temperature and time are 175 °C and 9 h, the as-synthesized CuII-SSZ-13 sample shows a stable framework structure, large specific surface area, and more [Z2CuII] speciation. This sample also shows excellent catalytic activity and hydrothermal stability. Characterization results also show that the microwave treatment can strengthen the Al-O-Si bonds in the zeolite framework. Our work provides a facile strategy to synthesize CuII-SSZ-13 zeolite and atomic-level understanding of catalytic property and hydrothermal stability.

A new CuII-dinuclear paddlewheel complex. Structural and electronic properties

A new paddlewheel dinuclear CuII complex [Cu2(HL)4(MeOH)2](MeOH)4, Cu2-PW was obtained using the 3,5-di‑tert‑butyl‑salicylic acid as a ligand (H2L). The Cu2-PW crystallizes in the monoclinic P2/c space group having a Cu…Cu distance of 2.5727(17) Å. The hydrogen bonds between coordinated and solvate methanol molecules link the structure into a pseudo-one-dimensional array with a Cu…Cu interdimer distance of 9.180(5) Å. Temperature dependence of magnetic susceptibilities revealed a strong antiferromagnetic interaction between the two CuII ions (J = −323 cm−1). DFT calculations showed that the strong antiferromagnetic behavior is originated from magnetic orbital centered only on CuII cations and carboxy oxygen atoms, with a calculated exchange magnetic coupling constant of J12= -311 cm−1. Time-dependent calculations were also performed to characterize the main electronic transition involved in the two well-defined maxima observed in solid-state. The results show that the maximum at 695 nm corresponds to d-d and carboxylate intraligand transitions, while the maximum centered at 320 nm was assigned to phenyl to carboxylate ILCT transition. The shoulder located around 400 nm corresponds to MLCT transition from HL− ligand to CuII center. In our knowledge, this is the first time that a copper paddlewheel complex with the salicylic ligand is studied using the hole-electron method to give a univocal assignment for the UV–vis spectrum.

Halido‐bridged Copper(II) Complexes with 1‐tert‐Butyl‐1H‐tetrazole: Crystal Structure and Magnetic Properties

Complex [Cu(tbt)Cl2]n (tbt = 1‐tert‐butyl‐1H‐tetrazole) was prepared by reaction of tbt with copper(II) chloride in solution. According to single‐crystal X‐ray analysis, this complex presents 1D coordination polymer, formed at the expense of double chlorido bridges between neighboring pentacoordinate copper(II) cations. 1‐tert‐Butyl‐1H‐tetrazole acts as monodentate ligand coordinated by CuII cations via the heteroring N4 atoms. The temperature‐dependent magnetic susceptibility measurements of novel complex [Cu(tbt)Cl2]n as well as described previously 1D coordination polymer [Cu(tbt)2Cl2]n, and linear trinuclear complex [Cu3(tbt)6Br6], were carried out. Magnetic studies revealed that the copper(II) ions were weakly ferromagnetically coupled in polymeric copper(II) chloride complexes, whereas complex [Cu3(tbt)6Br6] showed antiferromagnetic coupling.

Synthesis of optically active 3,3’-disubstituted biphenyl derivatives using palladium-catalyzed amination and their evaluation as enantioselective fluorescent detectors for amino alcohols and metal cations

The palladium-catalyzed amination was used to synthesize optically active 3,3’-diaminosubstituted biphenyl derivatives (in particular, macrocyclic derivatives) decorated with additional fluorophore groups (dansyl and 7-methoxycoumarin). The synthesized compounds were studied by spectroscopic methods (UV spectroscopy, fluorescence) in the presence of individual enantiomers of amino alcohols and metal salts. One of the synthesized compounds was demonstrated to serve as an enantioselective fluorescent detector for enantiomers of 2-amino-1-propanol because of different changes in the fluorescence spectra. Certain compounds can be used as molecular probes for the detection of CuII, AlIII, CrIII, and InIII cations due to characteristic changes in the fluorescence spectra upon the addition of metal perchlorates.