Zinc-Chelating Compounds as Inhibitors of Human and Bacterial Zinc Metalloproteases

Inhibition of bacterial virulence is believed to be a new treatment option for bacterial infections. In the present study, we tested dipicolylamine (DPA), tripicolylamine (TPA), tris pyridine ethylene diamine (TPED), pyridine and thiophene derivatives as putative inhibitors of the bacterial virulence factors thermolysin (TLN), pseudolysin (PLN) and aureolysin (ALN) and the human zinc metalloproteases, matrix metalloprotease-9 (MMP-9) and matrix metalloprotease-14 (MMP-14). These compounds have nitrogen or sulfur as putative donor atoms for zinc chelation. In general, the compounds showed stronger inhibition of MMP-14 and PLN than of the other enzymes, with Ki values in the lower μM range. Except for DPA, none of the compounds showed significantly stronger inhibition of the virulence factors than of the human zinc metalloproteases. TPA and Zn230 were the only compounds that inhibited all five zinc metalloproteinases with a Ki value in the lower μM range. The thiophene compounds gave weak or no inhibition. Docking indicated that some of the compounds coordinated zinc by one oxygen atom from a hydroxyl or carbonyl group, or by oxygen atoms both from a hydroxyl group and a carbonyl group, and not by pyridine nitrogen as in DPA and TPA.

Cocrystallization of Febuxostat with Pyridine Coformers: Crystal Structural and Physicochemical Properties Analysis

Drug cocrystals and salts have promising applications for modulating the physicochemical properties and solubility of pharmaceuticals. In this study, a cocrystal and two salts of febuxostat (FEB) with pyridine nitrogen coformers, including 4, 4′-bipyridine (BIP), 3-aminopyridine (3AP) and 4-hydroxypyridine (4HP), were designed to improve the solubility of FEB. The single-crystal structures were elucidated, and their physical and chemical properties were investigated by IR, PXRD, and DSC. In addition, drug-related properties, including the solubility and powder dissolution rate were assessed. The solubility and powder dissolution studies showed that the FEB-BIP cocrystal and FEB-3AP salt have superior dissolution compared to FEB.

Carbon Composites From Iron-chelating Pyridine Nitrogen-rich Coordinated Nanosheets for Oxygen Reduction

The exploration of a noble-metal-free and nitrogen-doped carbon (M-N/C) composite electrocatalyst for the oxygen reduction reaction (ORR) remains a great challenge. The activities of the M-N/C composite electrocatalysts are mainly affected by the metal active sites, pyridinic nitrogen, and graphitic nitrogen. In the present work, the iron-coordinated self-assembly is proposed for the preparation of iron-chelating pyridine nitrogen-rich coordinated nanosheet (IPNCN) composites as an electrocatalyst. Due to the highly conjugated structure of the IPNCN precursor, the pyridine nitrogen elements at both ends of the tetrapyrido [3,2-a:2',3'-c:3'',2''-h:2''',3'''-j] phenazine (TP) provide the multiple ligands, and the coordination interactions between the irons and the pyridine nitrogen further improve the thermodynamic stability, where the metal active sites and nitrogen elements are uniformly distributed in the whole structure. The resultant IPNCN composites exhibit excellent ORR performance with an onset potential of 0.93 V and a half potential of 0.84 V. Furthermore, the IPNCN composite electrocatalysts show the higher methanol resistance and electrochemical durability than the commercial Pt/C catalysts. It could be convinced that the as-designed IPNCN composite catalysts would be a promising alternative to the noble metal Pt-based catalysts in the practical applications.

Awn Stem-Derived High-Activity Free-Metal Porous Carbon for Oxidation Reduction

Designing oxygen reduction reaction (ORR) catalysts with excellent performance has far-reaching significance. In this work, a high-activity biomass free-metal carbon catalyst with N and S co-doped was successfully prepared by using the KOH activated awn stem powder as the precursor with organic matter pore-forming doping technology, which is named TAAS. The content of pyridine nitrogen groups accounts for up to 36% of the total nitrogen content, and a rich pore structure is formed on the surface and inside, which are considered as the potential active centers of ORR. The results show that the specific surface area of TAAS reaches 191.04 m2/g, which effectively increases the active sites of the catalyst, and the initial potential and half slope potential are as high as 0.90 and 0.76 V vs. RHE, respectively. This study provides a low-cost, environmentally friendly and feasible strategy for the conversion of low-value agricultural and forestry wastes into high value-added products to promote sustainable development of energy and the environment.

Bis(pyridine-2-carboxylato-κ2 N,O)copper(II)]–benzene-1,3,5-tricarboxylic acid–water (1/2/2)

In the title complex, [Cu(C6H4O2N)2]·2C9H6O6·2H2O, the Cu2+ ion lies on a center of inversion and coordinates with symmetry related pyridine nitrogen and carboxyl oxygen atoms from two pyridine-2-carboxylic acid anions, giving rise to a square-planar coordination geometry. There are weak axial bonds between Cu and an O atom of a symmetry-related trimesic acid moieties [Cu...O = 2.837 (2) Å] The Cu...O weak interactions and hydrogen bonds stabilize the whole structure.

Crystal structures of bis-{N-[1-(pyridin-2-yl-κN)ethylidene]nicotine hydrazide-κ2N’,O}cobalt(II)bis(perchlorate) dihydrate and bis-{N'-[1-(pyridin-2-yl-κN)ethylidene]nicotinohydrazide-κ2N',O}copper(II) perchlorate

Complexes of Co(II), [Co(C26H24N8O2)]·(ClO4)2·(H2O)2 (1), and Cu(II), [Cu(C26H23N8O2)]·(ClO4) (2), have been synthesized. The prepared two compounds were characterized by elemental analysis, infrared and their structures were determined by single-crystal X-ray diffraction. The compound 1 crystallizes in the triclinic space group P-1 with the following unit cell parameters: a = 8.880 (5) Å, b = 10.529 (5) Å, c = 18.430 (5) Å, α = 99.407 (5)°, β = 102.174 (5)°, γ = 100.652 (5)°, V = 1618.2 (13) Å3, Z = 2, T = 293(2), μ(MoKα) = 0.77 mm-1, Dcalc = 1.582 g/cm3, 16135 reflections measured (5.050° ≤ 2q ≤ 59.152°), 7648 unique, Rint = 0.034 which were used in all calculations. The final R1 was 0.066 (I ≥ 2σ(I)) and wR2 was 0.22 (all data). The compound 2 crystallizes in the monoclinic space group P21/c with the following unit cell parameters : a = 11.652 (5) Å, b = 16.540 (5) Å, c = 14.512 (5) Å, β = 93.495 (5)°, V = 2791.6 (18) Å3, Z = 4, T = 293(2), μ(MoKα) = 1.05 mm-1, Dcalc = 1.768 g/cm3, 15592 reflections measured (5.624° ≤ 2θ ≤ 58.804°), 6630 unique, Rint = 0.025 which were used in all calculations. The final R1 was 0.050 (I ≥ 2σ(I)) and wR2 was 0.144 (all data). In both complexes, the ligand acts in a tridentate fashion. In the structure of the mononuclear complex 1, the Co(II) cation is coordinated by two ligand molecules. The basal plane around the Co(II) cation is occupied by two pyridine nitrogen atoms and two carbonyl oxygen atoms. Two imino nitrogen atoms occupy the apical positions of the distorted square-pyramidal geometry. The mononuclear 2 consists of a Cu(II) coordinated by one ligand and one monodeprotonated ligand molecule. The metal center lies in a distorted square bipyramidal environment. The basal plane around the Cu(II) is occupied by two pyridine nitrogen atoms and two carbonyl oxygen atoms, the apical position being occupied by the two imino nitrogen atoms.

Spectroscopic Study of Metal (II) Complex of Sulphamethazine with 1,10 Phenanthroline

As part of the current research for more effective antimalarial drug, Cu (II) complex of sulphamethazine with 1,10 phenanthroline was synthesized. The novel complex was characterized by Elemental analysis, FT-IR and electronic spectroscopy. The novel complex is insoluble in water, which is an indication of covalent and non- electrolyte character. The elemental analysis result of the complex correspond with the proposed formula [Cu(SUF)(phen)(SCN)2]. The electronic spectrum of sulfamethazine and 1, 10- phen showed absorption bands at 212 nm (47169 cm−1) and 306 nm (32679 cm–1). These bands were assigned to the n – δ* and π – δ* transitions. The infrared bands were seen at 3443 – 3344 cm −1which were attributed to the presence of v(NH2), v(NH) and v (OH) vibrations experience bathochromic shift in the metal complex. The parent ligands acted as a bidentate chelating agent showing coordination through the pyridine nitrogen and the nitrogen of the NH moiety in this case.

Design of Ni3N/Co2N heterojunctions for boosting electrocatalytic alkaline overall water splitting

The heterojunction structure accelerates the overall water splitting for transition metal nitrides. Pyridine nitrogen and metal ions that act as catalytic sites synergistically promote the electrocatalytic process.