Copper(I) Cyanide Networks: Synthesis, Luminescence Behavior and Thermal Analysis. Part 1. Diimine Ligands

Reversible Cu-Nanoparticle Formation in Soft Hydrogel Composites: Towards Write-Erase Displays and Fluorescence Detection

In this study, we introduce a hydrogel-polymer microsphere (HPM) composite material constituted of PVA, glycerin, and polymer microspheres obtained from Pickering emulsions that are capable of adsorbing Cu2+ ions. The obtained HPM composite is soft, flexible, can be fully saturated with Cu2+ ions, and exhibits a reversible color transition from blue to black upon electrode contact or interaction with a reducing agent, due to in situ generation of copper nanoparticles (Cu-NPs). Because of the color contrast between the locally generated Cu-NPs and the background, the HPM can be used as substrate for stamping different shapes or writing text. Further, the surface can be erased by an acidic solution, which makes it interesting as flexible write-erase displays. A second feature of the HPM is that it can function as a fluorescence detector of cyanide ions. An HPM whose surface has been stamped with an electrode, upon contacting an aqueous solution containing cyanide ions, begins fluorescing a yellow-green light around the patterned area. The displayed luminescence is irreversible and is preserved even after HPM's drying or lyophilization. This work lays a foundational framework for future exploration of the HPM composites in various technological applications, for sensing, circuit printing, and flexible displays.

Hierarchical topological analysis of crystal structures: the skeletal net concept

Topological analysis of crystal structures faces the problem of the `correct' or the `best' assignment of bonds to atoms, which is often ambiguous. A hierarchical scheme is used where any crystal structure is described as a set of topological representations, each of which corresponds to a particular assignment of bonds encoded by a periodic net. In this set, two limiting nets are distinguished, complete and skeletal, which contain, respectively, all possible bonds and the minimal number of bonds required to keep the structure periodicity. Special attention is paid to the skeletal net since it describes the connectivity of a crystal structure in the simplest way, thus enabling one to find unobvious relations between crystalline substances of different composition and architecture. The tools for the automated hierarchical topological analysis have been implemented in the program package ToposPro. Examples, which illustrate the advantages of such analysis, are considered for a number of classes of crystalline substances: elements, intermetallics, ionic and coordination compounds, and molecular crystals. General provisions of the application of the skeletal net concept are also discussed.

Synthesis, decomposition studies and crystal structure of a three-dimensional CuCN network structure with protonated N-methylethanolamine as the guest cation

The compound poly[2-hydroxy-N-methylethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetragonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methylethanolamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N-H...O and O-H...O hydrogen bonds, and the cations interact with the 3D network via an unusual pair of N-H...N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130-250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.

1,3-Dithianes as Assembling Ligands for the Construction of Copper(I) Coordination Polymers. Investigation of the Impact of the RC(H)S2C3H6 Substituent and Reaction Conditions on the Architecture of the 0D-3D Networks

The parent compound 1,3-dithiane (L1) was reacted with CuI providing the 1D coordination polymer [{Cu(μ₂-I)₂Cu}(μ₂-L1)₂] _n (CP1), an isostructural compound [{Cu(μ₂-Br)₂Cu}(μ₂-L1)₂] _n (CP2) was isolated upon treatment of CuBr with L1. In contrast, treatment of L1 with CuCl results in the formation of 2D polymeric [{Cu(μ₂-Cl)₂Cu}(μ₂-L1)] _n (CP3), in which each sulfur atom acts as a 4-electron donor. The 1D compounds [{Cu(μ₂-X)₂Cu}(μ₂-L2)₂] _n (CP7, X = Br, and CP8, X = Cl) resulting from treatment of 2-methyl-1,3 dithiane (L2) with CuBr and CuCl are isostructural with their CuI homologue [{Cu(μ₂-I)₂Cu}(μ₂-L2)₂] _n (CP5), reported previously. Using CuCN, a 2D CP of composition [{Cu(μ₂-CN)₂Cu}(μ₂-L2)₂] _n (CP9) has been isolated. Complexation of 2-isobutyl-1,3-dithiane (L3) on CuI generates a 2D material [{Cu₃(μ₃-I)(μ₂-I)₂(μ₂-L3)₂}] _n (CP10), incorporating the usual trinuclear μ₃-I-capped Cu clusters as SBUs, whereas 2D-polymeric compounds [{Cu(μ₂-Br)₂Cu}(μ₂-L3)₂] _n (CP11) and [{Cu(μ₂-Cl)₂Cu}(μ₂-L3)₂] _n (CP12) were obtained with CuBr and CuCl. Treatment of 2-Me₃Si-1,3-dithiane (L4) with CuX yields the series [{Cu₂(μ₄-X)(μ₂-X)}(μ₂-L4)] _n (CP13-CP15). With 2-phenyl-1,3-dithiane (L5), the outcome of the reaction with CuI depends on the reaction conditions. Reaction with CuI in MeCN provides a 1D ribbon [{Cu(μ₂-I)₂Cu}(MeCN)₂(μ₂-L5)₂] _n (CP16), whereas treatment of CuI with L5 in hot EtCN yields 2D-polymeric[{Cu₃(μ₃-I)(μ₂-I)₂(μ₂-L5)₂}] _n (CP17). A reversible phase transition from triclinic P1̅ to monoclinic P2₁/ m is observed when recording the structure of CP16 at five different temperatures in the 100-300 K range. Ligand L6 containing a ferrocenyl function at the 2-position was also probed as organometallic dithioether ligand. Reaction of L6 with 1 equiv of CuI produces the 0D dinuclear complex [{Cu(μ₂-I)₂Cu}(η¹-L6)₂(MeCN)₂] (D1), whereas treatment with 2 equiv of CuI affords the novel 1D CP [{Cu(μ₃-I)₂Cu}(μ-L6)] _n (CP18), in which both S atoms of one L6 molecule span two copper centers of the infinite (CuI) _n ribbon. Some selected results of thermal analyses and luminescence measurements are also presented.

Self-assembly of supramolecular structure based on copper-lipopeptides isolated from e-waste bioleaching liquor

Supramolecular structures were produced by auto-assembling CuCN blocks derived from copper-lipopeptides (CuLps) isolated from bioleaching liquor. Lipopeptides produced by B. subtilis Hyhel1 have been previously related as responsible by bioleaching and intracellular copper crystal production. However, there were no records relating CuLps to extracellular copper crystal production. To study this process, CuLps were isolated from bioleaching liquor and kept at 8 °C to facilitate the CuLps aggregation. After three months, blue spheres (BS) were observed in the CuLp fraction. These spheres were then analyzed by SEM-EDS, MALDI-TOF-MS/MS, GC-MS and FTIR. SEM-EDS analysis showed that they were formed by polycrystalline structures mainly composed by Cu (46.5% m/m) and positioned concentrically. MALDI-TOF-MS/MS and GCMS showed that peptide bonds of CuLp were broken, producing lipid chains and amino acids free. The FTIR of BS showed three nitro groups: CN, NN and NO, which were not found in the control. These data suggest that the CuLp amino acid produced a CN group linked to copper, as CuCN blocks, that auto-assembled in supramolecular structures. This phenomenon could be explored as a method to recover copper and to obtain supramolecular CuCN structures, which in turn may be used as template for superconductor or computing devices.

Synthesis and Luminescence of Optical Memory Active Tetramethylammonium Cyanocuprate(I) 3D Networks

The structures of three tetramethylammonium cyanocuprate(I) 3D networks [NMe₄]₂[Cu(CN)₂]₂•0.25H₂O (1), [NMe₄][Cu₃(CN)₄] (2), and [NMe₄][Cu₂(CN)₃] (3), (Me₄N = tetramethylammonium), and the photophysics of 1 and 2 are reported. These complexes are prepared by combining aqueous solutions of the simple salts tetramethylammonium chloride and potassium dicyanocuprate. Single-crystal X-ray diffraction analysis of complex 1 reveals {Cu₂(CN)₂(μ₂-CN)₄} rhomboids crosslinked by cyano ligands and D_3h {Cu(CN)₃} metal clusters into a 3D coordination polymer, while 2 features independent 2D layers of fused hexagonal {Cu₈(CN)₈} rings where two Cu(I) centers reside in a linear C_∞v coordination sphere. Metallophilic interactions are observed in 1 as close Cu⋯Cu distances, but are noticeably absent in 2. Complex 3 is a simple honeycomb sheet composed of trigonal planar Cu(I) centers with no Cu^…Cu interactions. Temperature and time-dependent luminescence of 1 and 2 have been performed between 298 K and 78 K and demonstrate that 1 is a dual singlet/triplet emitter at low temperatures while 2 is a triplet-only emitter. DFT and TD-DFT calculations were used to help interpret the experimental findings. Optical memory experiments show that 1 and 2 are both optical memory active. These complexes undergo a reduction of emission intensity upon laser irradiation at 255 nm although this loss is much faster in 2. The loss of emission intensity is reversible in both cases by applying heat to the sample. We propose a light-induced electron transfer mechanism for the optical memory behavior observed.

Linear Copper Complex Arrays as Versatile Molecular Strings: Syntheses, Structures, Luminescence, and Magnetism

The defined linear arrangement of metal atoms in discrete coordination complexes or polymers is still one of the most intriguing challenges in synthetic chemistry. These chain arrangements are of fundamental importance, because of their potential applications as molecular wires and single molecule magnets (SMM) in microelectronic devices on a molecular scale. Oligonuclear Group 11 metal complexes with suitable bridging ligands, specifically those that are based on copper as the first choice of a cheap precursor coinage metal, are of particular interest in this regard. This is due to the superior luminescence properties of these linear clusters that often show d¹⁰ ⋅⋅⋅d¹⁰ interactions in their molecular structures. The combination of Cu^I with heavier coinage metal ions results in tunable emissive arrays that are also stimuli-responsive. Thus, both linear multinuclear Cu^I and linear heteropolymetallic Cu^I /Ag^I as well as Cu^I /Au^I clusters are excellent candidates for applications in molecular/organic light-emitting devices (OLEDs). Alternatively, paramagnetic multinuclear cupric arrays are prominent as potential molecular wires with enhanced magnetic properties through multiple coupled d⁹ centers. This Review covers the whole range of linear multinuclear assemblies of cuprous and cupric ions in complexes and coordination polymers, their syntheses, photophysical behavior, and magnetic properties. Moreover, recent advances in the rapidly progressing field of hetero-Cu^I /Ag^I and Cu^I /Au^I molecular strings are also discussed.

New Au(i)–Cu(i) heterometallic complexes: the role of bridging pyridazine ligands in the presence of unsupported metallophilic interactions

The use of N-donor pyridazine ligands in different amounts in the reaction with a Au(i)/Cu(i) precursor allows the control of metallophilic interactions in the solid state.

Strong luminescent copper(i) halide coordination polymers and dinuclear complexes with thioacetamide and N,N′-donor ligands

Ternary compounds based on copper(i) halides with thioacetamide and 4,4′-bipyridine or pyrazine have been prepared and characterized showing luminescence and semiconductivity.

Two copper(i) cyanide coordination polymers modified by semi-rigid bis(benzimidazole) ligands: syntheses, crystal structures, and electrochemical and photocatalytic properties

Two Cu(i) cyanide complexes with semi-rigid bis(benzimidazole) ligands were synthesized and characterized. Both complexes manifest photocatalytic activities for the degradation of methylene blue.

Electronic, bonding, and optical properties of 1d [CuCN]n (n = 1-10) chains, 2d [CuCN]n (n = 2-10) nanorings, and 3d [Cun (CN)n ]m (n = 4, m = 2, 3; n = 10, m = 2) tubes studied by DFT/TD-DFT methods

The electronic, bonding, and photophysical properties of one-dimensional [CuCN](n) (n = 1-10) chains, 2-D [CuCN](n) (n = 2-10) nanorings, and 3-D [Cu(n)(CN)(n)](m) (n = 4, m = 2, 3; n = 10, m = 2) tubes are investigated by means of a multitude of computational methodologies using density functional theory (DFT) and time-dependent-density-functional theory (TD-DFT) methods. The calculations revealed that the 2-D [CuCN](n) (n = 2-10) nanorings are more stable than the respective 1-D [CuCN](n) (n = 2-10) linear chains. The 2-D [CuCN](n) (n = 2-10) nanorings are predicted to form 3-D [Cun (CN)(n)](m) (n = 4, m = 2, 3; n = 10, m = 2) tubes supported by weak stacking interactions, which are clearly visualized as broad regions in real space by the 3D plots of the reduced density gradient. The bonding mechanism in the 1-D [CuCN](n) (n = 1-10) chains, 2-D [CuCN](n) (n = 2-10) nanorings, and 3-D [Cu(n)(CN)(n)](m) (n = 4, m = 2, 3; n = 10, m = 2) tubes are easily recognized by a multitude of electronic structure calculation approaches. Particular emphasis was given on the photophysical properties (absorption and emission spectra) of the [CuCN](n) chains, nanorings, and tubes which were simulated by TD-DFT calculations. The absorption and emission bands in the simulated TD-DFT absorption and emission spectra have thoroughly been analyzed and assignments of the contributing principal electronic transitions associated to individual excitations have been made.

Two novel topological structures of [Cu(CN)] coordination polymers modified by flexible triazole ligands

Triazole ligands have been introduced into the {Cu(CN)} skeleton to produce appealing polymers, which exhibit certain thermal stability and fluorescence properties.

Theoretical insights into the effect of amine and phosphine decoration on the photoluminescence of copper(i) and silver(i) coordination polymers

Ligand decoration shifts the excitation and emission spectra of coinage metal cyanides. DFT and TD-DFT calculations are used to identify the MOs involved the transitions that contribute to photoluminescence.

A cyano-bridged copper(ii)–copper(i) mixed-valence coordination polymer as a source of copper oxide nanoparticles with catalytic activity in C–N, C–O and C–S cross-coupling reactions

A cyano-bridged Cu(ii)–Cu(i) complex was synthesized and transformed into CuO nanoparticles. Their catalytic activity in C–N, C–O, and C–S cross-coupling reactions was explored.

A cyano and end-to-end azido bridged 3D copper(ii)–copper(i) mixed-valence coordination polymer and its transformation to copper nitride nanoparticles

Syntheses and characterization of a CN and end-to-end N₃ bridged three-dimensional Cu(II)–Cu(I) mixed valence polymer (1), with Cu-N₃ system without CN (2) and a CN-bridged Cu analogue without N₃ (3) are reported and solid-state transformation of the 1 to copper nitride nanoparticles performed.

Structure and applications of metal-organic framework based on cyanide and 3,5-dichloropyridine

The reaction of the aqueous/acetonitrile solutions of K3[Cu(CN)4] and 3,5-dichloropyridine (3,5-dClpy), in the presence of Me3SnCl affords a new metal-organic framework (MOF), (3)∞[(CuCN)2·(3,5-dClpy)2], 1. The structure of the MOF 1 was characterized by IR, UV-visible, TGA and X-ray single crystal analysis. The structure of MOF 1 consists of CuCN building blocks which are connected by CN group forming 1D-zig-zag chains. Each chain is bridged to another chain by hydrogen bonding organizing 2D-sheets. The structure of 1 is further close packed by hydrogen bonds, π-π stacking and lp-π interactions creating 3D-network. The emission spectra and the thermodynamic parameters from TGA of the MOF 1 were discussed. The MOF 1 was used as heterogeneous catalyst for the oxidative discoloration of methylene blue dye (MB) by dilute solution of hydrogen peroxide as oxidant. The in vitro cytotoxic activity has been evaluated against the human breast cancer cell lines MCF-7. The cytotoxic effect of the MOF 1 on the viability of MCF-7 cells was determined by MTT assay.

Poly[tetraamminecopper(II) bis[tris(μ2-cyanido-κ2C,N)dicuprate(I)]]: a unique Cu(I)-Cu(II) mixed-valence complex containing anionic cuprous cyanide layers and [Cu(NH3)4]2+ cations

The title compound, {[Cu(NH(3))(4)][Cu(CN)(3)](2)}(n), features a Cu(I)-Cu(II) mixed-valence CuCN framework based on {[Cu(2)(CN)(3)](-)}(n) anionic layers and [Cu(NH(3))(4)](2+) cations. The asymmetric unit contains two different Cu(I) ions and one Cu(II) ion which lies on a centre of inversion. Each Cu(I) ion is coordinated to three cyanide ligands with a distorted trigonal-planar geometry, while the Cu(II) ion is ligated by four ammine ligands, with a distorted square-planar coordination geometry. The interlinkage between Cu(I) ions and cyanide bridges produces a honeycomb-like {[Cu(2)(CN)(3)](-)}(n) anionic layer containing 18-membered planar [Cu(CN)](6) metallocycles. A [Cu(NH(3))(4)](2+) cation fills each metallocyclic cavity within pairs of exactly superimposed {[Cu(2)(CN)(3)](-)}(n) anionic layers, but there are no cations between the layers of adjacent pairs, which are offset. Pairs of N-H···N hydrogen-bonding interactions link the N-H groups of the ammine ligands to the N atoms of cyanide ligands.