Micro-level Estimation of Mercaptoacetic Acid Using its Inhibitory Effect to Mercury Catalyzed Ligand Exchange Reaction of Hexacyanoruthenate(II)

The sulfur-containing bioactive molecules (soft base) tends to bind strongly with Hg(II) (soft acid), thereby inhibiting the mercury (II) catalyzed exchange rate of cyanide ligand from [Ru(CN)6]4- by pyrazine. This inhibitory effect of Mercaptoacetic acid (MAA) encourages us to establish a new kinetic method for its micro-level estimation. Optimized reaction condition viz. 6.25×10-5 M [Ru(CN)64-], pH = 4.0, 7.5×10-4 M [Pyrazine], 0.05 M KCl, 8.5 ×10-5 M [Hg+2] and 45 (±0.1) oC temperature were utilized for the kinetic spectrophotometric investigation at 370nm (λmax of [Ru(CN)5 Pz]3- complex). The modified mechanistic scheme for inhibition caused by sulfur donor ligand, MAA has been proposed. The proposed analytical method provides the detection of MAA up to 2.0 × 10-6 M, indicates that the methodology can be effectively and economically employed to analyze the biological samples having MAA. This method can also be convincingly adopted for the quality check of MAA containing industrial products.

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

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 novel one-dimensional metal–organic framework with a μ-cyanido-argentate group:catena-poly[[(5,5′-dimethyl-2,2′-bipyridyl-κ2N,N′)silver(I)]-μ-cyanido-κ2N:C]

The design and synthesis of metal coordination and supramolecular frameworks containingN-donor ligands and dicyanidoargentate units is of interest due to their potential applications in the fields of molecular magnetism, catalysis, nonlinear optics and luminescence. In the design and synthesis of extended frameworks, supramolecular interactions, such as hydrogen bonding, π–π stacking and van der Waals interactions, have been exploited for molecular recognition associated with biological activity and for the engineering of molecular solids.The title compound, [Ag(CN)(C12H12N2)]n, crystallizes with the AgIcation on a twofold axis, half a cyanide ligand disordered about a centre of inversion and half a twofold-symmetric 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbpy) ligand in the asymmetric unit. Each AgIcation exhibits a distorted tetrahedral geometry; the coordination environment comprises one C(N) atom and one N(C) atom from substitutionally disordered cyanide bridging ligands, and two N atoms from a bidentate chelating 5,5′-dmbpy ligand. The cyanide ligand links adjacent AgIcations to generate a one-dimensional zigzag chain. These chains are linked togetherviaweak nonclassical intermolecular interactions, generating a two-dimensional supramolecular network.

Advances in f-element cyanide chemistry

By using the cyanide ligand, actinide compounds with unprecedented structures, UIII–CN vs. CeIII–NC and UIII–CN vs. UIV–NC coordination modes, and novel high-valent uranium complexes were revealed.