A novel three-dimensional copper(I) cyanide coordination polymer constructed from various bridging ligands: synthesis, crystal structure and characterization

Abstract

The cyanide ligand can act as a strong σ-donor and an effective π-electron acceptor that exhibits versatile bridging abilities, such as terminal, μ2-C:N, μ3-C:C:N and μ4-C:C:N:N modes. These ligands play a key role in the formation of various copper(I) cyanide systems, including one-dimensional (1D) chains, two-dimensional (2D) layers and three-dimensional (3D) frameworks. According to the literature, numerous coordination polymers based on terminal, μ2-C:N and μ3-C,C,N bridging modes have been documented so far. However, systems based on the μ4-C:C:N:N bridging mode are relatively rare. In this work, a novel cyanide-bridged 3D CuI coordination framework, namely poly[(μ2-2,2′-biimidazole-κ2 N 3:N 3′)(μ4-cyanido-κ4 C:C:N:N)(μ2-cyanido-κ2 C:N)dicopper(I)], [Cu2(CN)2(C6H6N4)] n , (I), was synthesized hydrothermally by reaction of environmentally friendly K3[Fe(CN)6], CuCl2·2H2O and 2,2′-biimidazole (H2biim). It should be noted that cyanide ligands may act as reducing agents to reduce CuII to CuI under hydrothermal conditions. Compound (I) contains diverse types of bridging ligands, such as μ4-C:C:N:N-cyanide, μ2-C:N-cyanide and μ2-biimidazole. Interestingly, the [Cu2] dimers are bridged by rare μ4-C:C:N:N-mode cyanide ligands giving rise to the first example of a 1D dimeric {[Cu2(μ4-C:C:N:N)] n+} n infinite chain. Furthermore, adjacent dimer-based chains are linked by μ2-C:N bridging cyanide ligands, generating a neutral 2D wave-like (4,4) layer structure. Finally, the 2D layers are joined together via bidentate bridging H2biim to create a 3D cuprous cyanide network. This arrangement leads to a systematic variation in dimensionality from 1D chain→2D sheet→3D framework by different types of bridging ligands. Compound (I) was further characterized by thermal analysis, solid-state UV–Vis diffuse-reflectance and photoluminescence studies. The solid-state UV–Vis diffuse-reflectance spectra show that compound (I) is a wide-gap semiconductor with band gaps of 3.18 eV. The photoluminescence study shows a strong blue–green photoluminescence at room temperature, which may be associated with metal-to-ligand charge transfer.

A two-dimensional semiconducting Cu(i)-MOF for binder and conductive additive-free supercapattery

“…Further, the bond angles between Cu and μ 2 -C:N: Cu2–C9–N5 and Cu1–N5–C9 are 174.5(6) and 177.4(6)° suggesting a linear arrangement. The C–N bond lengths of 1.153(9) and 1.161(8) Å for C8–N6 and C9–N5 are close to the reported C–N bond length in CuCN-MOF s. 60 The bond length of Cu1 1 –C8 is 2.281(8) whereas the Cu2–C9 bond length is 1.874(6) Å. The Cu–Cu distances between each rectangular face are shown in Fig.…”

“…The Cu1-Cu1 1 bond distance is 2.447(17) Å, shorter than the sum of van der Waals radii, and is close to the previously reported for Cu2-m 2 C:N units. 58,59 The bond lengths of Cu1-N4 and Cu1-N5 are 2.070(5) and 1.930 (5), and those of Cu2-N1 2 , Cu2-N3 2 , and Cu2-N6 3 60 The bond length of Cu1 1 -C8 is 2.281(8) whereas the Cu2-C9 bond length is 1.874(6) Å. The Cu-Cu distances between each rectangular face are shown in Fig.…”

Hofmann‐Type Cyanide Bridged Coordination Polymers for Advanced Functional Nanomaterials

“…A number of compounds were prepared in the same context by introducing rigid and flexible ligands such as the 1D chain [{Cu(CN)} 3 (phen)] n (18), [87] 2D layer 19), [88] [{Cu(CN)} 2 (4,4′-bipy)] n ( 19), [87] [{Cu(CN)} 4 (bpp) 2 n (20), [87] and a 3D [Cu 2 (CN) 2 (C 6 H 6 N 4 )] n (21). [5] Four ternary CN-CPs; 24), Hdptrz = 3,5-dipropyl-1H-1,2,4-triazole ( 25)) were reported by Ling et a. [89] The CN-groups are all in situ generated from C-C cleavage reaction of acetonitrile.…”

“…The cyanide anions can thus bridge between terminal and linker locations with a variety of methods (Scheme 1). [5] The functional characteristics of this class of materials are extremely intriguing in relation to their shape and composition, and include storage, [2b] supercapacitors, [6] switching, [7,8] catalysis, [9,10] biocompatibility, [11,12] electrochemistry, [13] adsorption, [14] separation, [2a] and magnetism, [15,16] and optical and calorimetric properties. [17] In addition to the successful preparation of their powders and solids in various forms, many researchers have successfully reported the controlled growth and deposition of thin films anchored on substrates through a variety of processes, such as the sequential deposition process, [18] epitaxial and oriented crystal growth, [19,20] step-by-step growth, [21,22] in situ crystallization, [23,24] multiple sequential adsorption, [25,26] electrochemical deposition, [27][28][29][30][31] spin coating, and grafting on surfaces or matrix.…”

“…Metal-cyanide complexes' cyanide bridging modes. [5] stituting M' by a metal ion with tetrahedral coordination (i.e., Cd, Hg). [39] One of the simple bridges that is essential to the physical and chemical characteristics of metal cyanometallate is the cyanide group.…”