ZnO nanoparticles favours heterogeneous nucleation in PET–ZnO nanocomposites

The structural and chemical properties with non-isothermal crystallization kinetics of PET–ZnO nanocomposites have been reported in this article. ZnO nanoparticles have been synthesized via chemical route with average diameter 19 nm which made confirm by transmission electron microscopy and X-ray diffractometer (XRD) techniques. PET–ZnO nanocomposites have been prepared by solution casting method. The structural and chemical changes occurred in poly (ethylene terephthalate) after inclusion of ZnO nanoparticles have been studied with the help of XRD and Fourier transform infrared spectroscopy, respectively. It was observed from differential scanning calorimeter that ZnO nanoparticles work as nucleating agent for heterogeneous nucleation in PET matrix under non-isothermal crystallization process. The combined Avrami and Ozawa models have been proved adequate to explain non-isothermal crystallization kinetics of PET–ZnO nanocomposites, and also, ZnO nanoparticles have been caused to reduce crystallization activation energy in pristine PET as per the applied Kissinger model.     

Anion‐ and Spacer‐Directed Host–Guest Complexes of Bipyridine with Pyrogallol[4]arene

New oval‐shaped capsular and bilayer‐type hydrogen‐bonded arrangements of C‐propyl‐ol‐pyrogallol[4]arene (PgC3‐OH) with bipyridine‐type spacer complexes are reported here. These complexes are engineered by virtue of derivatization of C‐alkyl tails of pyrogallol[4]arene and the use of divergent spacer ligands. Complexes of PgC3‐OH, PgC3‐OH with bpy (4,4′‐bipyridine) and PgC3‐OH with bpa (1,2‐bis(4‐pyridyl)acetylene) have bilayer type arrangements; however, the use of hydrogen chloride causes protonation of bpy molecule, which is then entrapped flat within an offset oval‐shaped dimeric hydrogen‐bonded PgC3‐OH nanocapsule. The presence of chloride anion in the crystal lattice controls the geometry of the resultant nanoassembly.     

Urea derivatives of piperazine doped with pyrazole-4-carboxylic acids: Synthesis and antimicrobial evaluation

A series of novel N-cycloalkyl/aryl-4-(1,3-diphenyl-1H-pyrazole-4-carbonyl)piperazine-1-carboxamides 9a-g has been synthesized for biological interest by simple base catalyzed reaction of various N-cycloalkyl/aryl isocyanates with (1,3-diphenyl-1H-pyrazol-4-yl)(piperazin-1-yl)methanone hydrochloride 8 . The compound 8 was synthesized in excellent yield by the reaction of 1,3-diphenyl-1H-pyrazole-4-carbonyl chloride with boc-piperazine followed by deprotection of boc group with dioxane-HCl. All the novel intermediates and urea derivatives have been screened for antimicrobial activity. The compound 9a was found an excellent compound to be active against all Gram (−ve) and Gram (+ve) bacterial strains E. coli, Y. enterocolitica, B. cereus, and S. aureus. It also showed comparable antifungal activity against C. albicans with MIC 78.1 μg/ml as compared to reference standard miconazole.     

Exploring the ellipsoidal and core-shell geometries of copper-seamed C-alkylpyrogallol[4]arene nanocapsules in solution

Small-angle neutron scattering (SANS) studies were used to probe the stability and geometry of copper-seamed C-alkylpyrogallol[4]arene (PgC(n)Cu; n = 11, 13, 17) hexamers in solution. Novel structural features are observed at chain lengths greater than 10 in both solid and solution phase. Scattering data for the PgC(11)Cu and PgC(13)Cu in chloroform fitted as core-shell spheres with a total spherical radius of about 22.7 and 22.9 ? respectively. On the other hand, the scattering curve for the PgC(17)Cu hexamer at both 1% and 5% mass fractions in o-xylene did not fit as a discrete sphere but rather as a uniform ellipsoid. The geometric dimensions of the ellipsoid radii are 24 ? along the minor axis and 115 ? along the major axis. It is expected that an individual hexamer with heptadecyl chains would exhibit a uniform radius of ca. 24 ?. However, an approximate ratio of 1:5 between radii lengths for the minor axis and major axis is consistent with interpenetration of the heptadceyl chains of adjacent hexamers to form a single ellipsoidal assembly.     

Room-Temperature Dialkylamination of Chloroheteroarenes Using a Cu(II)/PTABS Catalytic System

The dimethylamino functionality has significant importance in industrially relevant molecules and methodologies to install these efficiently are highly desirable. We report herein a highly efficient, room-temperature dimethylamination of chloroheteroarenes performed via the in-situ generation of dimethylamine using N,N-dimethylformamide (DMF) as precursor wiith a large substrate scope that includes various heteroarenes, purines as well as commercially relevant drugs such as altretamine, ampyzine and puromycin precursor.