Chemistry

Addressed herein, monodisperse platinum nanoparticles (Pt (0)/DPA@GO NPs), supported on graphene oxide (GO), have been prepared by sonochemical double solvent reduction method by the help of dipropylamine (DPA) as a stabilizer at room temperature and used as a catalyst for both C 1 to C 3 alcohol oxidation reaction and the dehydrogenation of dimethylamine-borane ((CH 3) 2 NHBH 3) at room temperature. Monodisperse Pt (0)/DPA@GO NPs were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), ICP-OES, and electrochemical measurements (CV). The catalytic performance of the monodisperse Pt NPs demonstrated that they were highly efficient and reusable catalysts even at low temperature for both methanol, ethanol and 2-propanol oxidations. The prepared nanoparticles can also catalyse the dehydrogenation of DMAB with very high activity (TOF ¼ 35.82 h À1) at room temperature. The prepared monodisperse Pt (0)/DPA@GO NPs have~11.6, 16.8 and 7.61 times higher catalytic activities than the commercially available Pt (ETEK) catalyst towards C 1 to C 3 alcohol oxidation reactions, respectively. The exceptional catalytic activity and stability of highly efficient monodisperse Pt nanoparticles towards agglomeration leaching and CO poisoning allow these particles to be recycled and reused in the catalysis of DMAB dehydrogenation and C 1 to C 3 alcohol oxidation. After fifth subsequent reaction and recovery cycles, the prepared nanocatalyst retained almost >80% activity towards the complete dehydrogenation of DMAB and C 1 to C 3 alcohol oxidation.

A series of novel urea and thiourea derivatives of valacyclovir were efficiently synthesized in high yields and evaluated their antiviral activity. 2-((6-Amino-4-oxo-4,5-dihydro-1H-imidazo[4,5-c]pyridin-1-yl)methoxy)ethyl-2-amino-3-ethylbutanoate (valacyclovir) 1 is reacted with various aromatic isocyanates/thiocyanates 2 in the presence of N, N-dimethyl piperazine as a base in THF: pyridine (4:1) to obtain valacyclovir urea/thiourea derivatives 3(a-j). The structures of the title compounds 3(a-j) were confirmed by IR, NMR ( 1 H, 13 C), mass spectral and elemental analysis. The newly synthesized compounds were screened for their antiviral activity against Tobacco mosaic virus (TMV) and antioxidant activity was evaluated by DPPH, SOD and GST methods. The title compounds exhibited potent antiviral and good antioxidant activities.

ObjectivesTwo new metal complexes, diaquabis(4-benzoyl-1,5-diphenyl-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3-carboxamide)cobalt(II) dihydrate (2) and diaquabis(ethyl-1-(3-nitrophenyl)-5-phenyl-3-(5-sulfamoyl-1,3,4-thiadiazol-2-ylcarbamoyl)-1H-pyrazole-4-carboxylate)cobalt(II) monohydrate (4), containing sulfonamide have been synthesized by the reaction of Co(II) with 4-benzoyl-1,5-diphenyl-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3-carboxamide (1) and ethyl-1-(3-nitrophenyl)-5-phenyl-3-(5-sulfamoyl-1,3,4-thiadiazol-2-ylcarbamoyl)-1H-pyrazole-4-carboxylate (3), respectively.Two new metal complexes, diaquabis(4-benzoyl-1,5-diphenyl-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3-carboxamide)cobalt(II) dihydrate (2) and diaquabis(ethyl-1-(3-nitrophenyl)-5-phenyl-3-(5-sulfamoyl-1,3,4-thiadiazol-2-ylcarbamoyl)-1H-pyrazole-4-carboxylate)cobalt(II) monohydrate (4), containing sulfonamide have been synthesized by the reaction of Co(II) with 4-benzoyl-1,5-diphenyl-N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3-carboxamide (1) and ethyl-1-(3-nitrophenyl)-5-phenyl-3-(5-sulfamoyl-1,3,4-thiadiazol-2-ylcarbamoyl)-1H-pyrazole-4-carboxylate (3), respectively.MethodsThe structures of Co(II) complexes 2 and 4 have been characterised by spectroscopic methods and elemental analyses. Human carbonic anhydrase isoenzymes (hCA-I and hCA-II) were purified from erythrocyte cells by affinity chromatography. The inhibitory effects of ligands 3 and 4, acetazolamide as a control compound and the newly synthesized complexes on the activity of hydratase and esterase of these isoenzymes have been studied in vitro.The structures of Co(II) complexes 2 and 4 have been characterised by spectroscopic methods and elemental analyses. Human carbonic anhydrase isoenzymes (hCA-I and hCA-II) were purified from erythrocyte cells by affinity chromatography. The inhibitory effects of ligands 3 and 4, acetazolamide as a control compound and the newly synthesized complexes on the activity of hydratase and esterase of these isoenzymes have been studied in vitro.Key findingsThe concentration of compounds 2 and 4 producing a 50% inhibition of hydratase activity (IC50 values) were 0.473 ± 0.025 and 0.065 ± 0.002 μm for hCA-I and 0.213 ± 0.015 and 0.833 ± 0.021 μm for hCA-II, respectively. The IC50 values of synthesized compounds 2 and 4 for esterase activity were, 0.058 ± 0.006 and 0.297 ± 0.015 μm for hCA-I and 0.110 ± 0.010 and 0.052 ± 0.002 μm for hCA-II, respectively. In relation to esterase activity, the inhibition equilibrium constants (Ki) were determined as 0.039 ± 0.004 and 0.247 ± 0.035 μm on hCA-I and 0.078 ± 0.002 and 0.363 ± 0.015 μm on hCA-II for 2 and 4, respectively.The concentration of compounds 2 and 4 producing a 50% inhibition of hydratase activity (IC50 values) were 0.473 ± 0.025 and 0.065 ± 0.002 μm for hCA-I and 0.213 ± 0.015 and 0.833 ± 0.021 μm for hCA-II, respectively. The IC50 values of synthesized compounds 2 and 4 for esterase activity were, 0.058 ± 0.006 and 0.297 ± 0.015 μm for hCA-I and 0.110 ± 0.010 and 0.052 ± 0.002 μm for hCA-II, respectively. In relation to esterase activity, the inhibition equilibrium constants (Ki) were determined as 0.039 ± 0.004 and 0.247 ± 0.035 μm on hCA-I and 0.078 ± 0.002 and 0.363 ± 0.015 μm on hCA-II for 2 and 4, respectively.ConclusionsThe synthesized compounds 2 and 4 had effective inhibitory activity (P < 0.0001) on hCA-I and hCA-II than the corresponding free ligands, 1 and 3, and acetazolamide. Compounds 2 and 4 might be considered as potential inhibitors.The synthesized compounds 2 and 4 had effective inhibitory activity (P < 0.0001) on hCA-I and hCA-II than the corresponding free ligands, 1 and 3, and acetazolamide. Compounds 2 and 4 might be considered as potential inhibitors.

Pyrazole is a heterocyclic organic compound having a 5-membered ring structure with three carbon atoms and two neighbor nitrogen atoms. There are several applications of pyrazole core based organic molecules in various areas including pharmacy and agro-chemical industries. There is an increase in the interest of synthesizing, analyzing different properties, and seeking possible applications of pyrazole derivatives. Our research efforts have been focusing on different aspects of pyrazoles including facile synthesis, their behavior in biodegradable polymers, and investigating their bioactivity. In this short review article, the aim is to show the trend in the research on pyrazole derivatives.

Silver nanoparticles were synthesized by a simple, non-toxic, eco-friendly biological reduction method using colocasia extract as reducing agent. A variety of nanoparticles were formed when the concentration of the reducing agent was increased with respect to the silver nitrate solution. The reaction mixtures displayed variation in colours and characteristic UV-VIS spectra of silver nanoparticles with the increasing concentration of colocasia extract. A single SPR band in between 419 to 438 nm in UV-VIS spectroscopy revealed the formation of silver nanoparticles. TEM analysis of the silver nanoparticles confirmed the spherical shape and size distribution of the nanoparticles found in the range of 10-30nm. Antibacterial activity of the Ag-NPs was confirmed by disk diffusion method against Bacillus flexus, Escherichia coli, Serratia marcescens and Staphylococcus aureus.