Synthesis,Structural and Energetic Properties of Copper(II) Perchlorate Complex with Aminoguanidine

The complexation of copper(II) perchlorate with aminoguanidine hemesulfate (AGHS) yield related mononuclear complex bis(aminoguanidine)copper(II) perchlorate; [Cu(AG)₂](ClO₄)₂ ( I ). The characterization of complex I was done by elemental analysis, electronic spectra, IR studies, and X‐ray diffraction. From analytical data, a stoichiometry of 1:2 of metal to ligand was determined for the complex. The structure consists of centrosymmetric square planar [Cu(AG)₂]²⁺ cations and perchlorate counterions. The Cu^II atom is four‐coordinate by two imine N atoms and two amine N atoms from two aminoguanidine ligands, forming a slightly distorted square‐planar coordination. In the crystal structure, molecules are linked through intermolecular N–H ··· O hydrogen bonds, forming a network. The thermal decomposition process of this complex was investigated through differential scanning calorimetry (DSC) and the sensitivities toward impact and friction were assessed using a BAM drophammer and a BAM friction tester.     

Efficient Synthesis of Novel Thiazol‐2‐ylidene‐amides Using Carbonylthiourea Building Blocks

In this work, an efficient and versatile synthesis of novel thiazol‐2‐ylidene‐amides from various carbonylthiourea derivatives is described. A sequential alkylation–cyclization reaction between thioureas and propargyl bromide in the presence of DABCO in refluxing ethanol afforded 4‐methylthiazol‐2(3H)‐ylidene‐amide derivatives in good yields.     

Straightforward Approach Toward Dihydrothiazoles via Intramolecular Bromocyclization

An intramolecular bromonium ion–assisted cyclization with sulfur as an internal nucleophile is described. Starting from benzoyl chlorides, this method provides an easy procedure for the synthesis of dihydrothiazole derivatives in moderate to good yields.     

Synthesis, characterization and investigation of catalytic activity of a highly sulfonated carbon solid acid in the synthesis of dihydropyrimidinones under solvent-free conditions

A highly sulfonated carbon as an efficient, recyclable, nontoxic and green solid acid catalyst was synthesized readily by simultaneous sulfonation, dehydration and carbonization of sucrose C¹²H²²O¹¹ in sulfuric acid and was characterized with Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric and differential thermal gravimetric analysis (TG-DTG), X-ray diffraction (XRD), carbon-hydrogen-nitrogen-sulfur analysis (CHNS), neutralization potentiometric titration and scanning electron microscopy (SEM). This new catalyst was used in one pot three-component condensation reaction of various aromatic aldehydes with ??-ketoester and urea under solvent-free conditions to afford the corresponding dihydropyrimidinones (DHPMs). This catalyst can be reused several times without loss of its activity.     

Computational study of a latent heat thermal energy storage system enhanced by highly conductive metal foams and heat pipes

Numerical simulations are performed to analyze the thermal characteristics of a latent heat thermal energy storage system with phase change material embedded in highly conductive porous media. A network of finned heat pipes is also employed to enhance the heat transfer within the system. ANSYS-FLUENT 19.0 is used to create a transient multiphase computational model to simulate the thermal behavior of the storage unit. Copper foam is the porous medium used to enhance the heat transfer and is impregnated with the phase change material, potassium nitrate (KNO₃). The effects of the porosity of the metal foam and the quantity of heat pipes on the thermal characteristics of storage unit have been investigated. The results indicated that increasing the quantity of the embedded heat pipes leads to drastic acceleration of both charging and discharging process. Impregnating the copper foam with potassium nitrate phase change material significantly affects the total charging and discharging times of the storage unit. It was shown that the porosity of the metal foam plays a key role in the thermal behavior of the system during the charging and discharging processes.

     

Benzoylquinazolinone derivatives as new potential antidiabetic agents: α-Glucosidase inhibition,kinetic, and docking studies

Benzoylquinazolinone derivatives 3a–n were synthesized via a simple one-step reaction, and evaluated for in vitro α-glucosidase inhibitory activity. Compounds 3d , 3f–g , 3i , and 3m–n showed more inhibitory activity than standard drug acarbose (IC₅₀ = 750.0 ± 1.5 μM), and among them, compound 3d displayed the highest α-glucosidase inhibitory activity (IC₅₀ = 261.6 ± 0.1 μM). The kinetic analysis of the compound 3d revealed that this compound inhibited α-glucosidase in a competitive manner (K_i = 255 μM). The docking studies were applied to predict binding modes of the synthesized compounds in active site of α-glucosidase.     

Synthesis of β -Dihydroxysulfides by Cleavage of Epoxides Using Quaternized Amino-Functionalized Cross-Linked Polyacrylamide as a New Polymeric Phase Transfer Catalyst

Poly[N-(2-aminoethyl)acrylamido]trimethyl ammonium halide resin was developed as a new solid-liquid phase transfer catalyst. This quaternized polyacrylamide catalyzed regioselective ring opening of epoxide by Na ₂ S to obtain bis[β -hydroxy-alkyl]sulfide in high yield under mild conditions.     

Controlling size, shape and homogeneity of embryoid bodies using poly(ethylene glycol) microwells

Directed differentiation of embryonic stem (ES) cells is useful for creating models of human disease and could potentially generate a wide array of functional cell types for therapeutic applications. Methods to differentiate ES cells often involve the formation of cell aggregates called embryoid bodies (EBs), which recapitulate early stages of embryonic development. EBs are typically made from suspension cultures, resulting in heterogeneous structures with a wide range of sizes and shapes, which may influence differentiation. Here, we use microfabricated cell-repellant poly(ethylene glycol) (PEG) wells as templates to initiate the formation of homogenous EBs. ES cell aggregates were formed with controlled sizes and shapes defined by the geometry of the microwells. EBs generated in this manner remained viable and maintained their size and shape within the microwells relative to their suspension counterparts. Intact EBs could be easily retrieved from the microwells with high viability (>95%). These results suggest that the microwell technique could be a useful approach for in vitro studies involving ES cells and, more specifically, for initiating the differentiation of EBs of greater uniformity based on controlled microenvironments.     

Electropolymerization of N,N-dimethylaniline in presence of sodium dodecyl sulfate and its electrochemical properties

Poly(N,N-dimethylaniline) (PDMA) was formed by successive cyclic voltammetry in monomer solution in the presence of sodium dodecyl sulfate (SDS) on the surface of a carbon paste electrode. The polymerization behavior of N,N-dimethylaniline in the presence of SDS is quite different from that of N,N-dimethylaniline in the absence of SDS. The effect of varying amount of SDS on the rate of polymerization of N,N-dimethylaniline was investigated. The electrochemical behavior of the SDS-PDMA carbon paste electrode has been investigated by cyclic voltammetry in 0.5 M H₂SO₄ and 5 mM K₄[Fe(CN)₆]/0.1 M KCl solutions as the supporting electrolyte and model system, respectively. The synthesized PDMA was characterized by FT-IR and scanning electron microscopy (SEM). Ni(II) ions were incorporated into the electrode by immersion of the polymeric modified electrode having amine groups in 0.1 M Ni(II) ion solution. The electro catalytic oxidations of methanol at the surface of the Ni/SDS-PDMA electrode were studied in a 0.1 M NaOH solution. Compared to bare carbon paste and PDMA-modified carbon paste electrodes; the SDS-PDMA electrode significantly enhanced the catalytic efficiency of Ni ions for methanol oxidation.