[en] The template synthesis of copper(II) and nickel(II) complexes derived from 2,6-diformyl-4-methylphenol with diethylenetriamine or 1,2-bis(3-amino propylamino)ethane produce the 12-membered N₃O and 17-membered N₄O macrocyclic complexes, respectively. The geometry of the complexes has been determined with the help of electronic and EPR spectroscopic values and found to be five coordinated square pyramidal and, six coordinated distorted tetragonal for 12-membered and 17-membered macrocyclic complexes, respectively. Electrochemical studies of the mononuclear N₃O and N₄O copper(II) complexes show one irreversible one electron reduction wave at E^pc = .1.35 and .1.15 V respectively, and the corresponding nickel(II) complexes show irreversible one-electron reduction wave at E^pc = .1.25 and .1.22 V, respectively. The nickel(II) complexes show irreversible one-electron oxidation wave at Epa = +0.84 and +0.82 V, respectively. All the complexes were evaluated for in vitro antimicrobial activity against the human pathogenic bacteria and fungi

[en] Highlights: • The rinds of G. mangostana are discarded as wastes after fruit consumption can be effectively used for synthesizing nanoparticles. • The reduction potential of aqueous rind extract of G. mangostana was relatively higher with HAuCl₄ than AgNO₃ and H₂PtCl₆. • The gold nanoparticles were stable for over 6 months at 4C and this property can be exploited for fabrication of drugs. • Conjugation of antibiotics with nanoparticles has drastically enhanced the antibacterial activity when compared to bare nanoparticles. • Bacillus sp. which is inherently resistant to free streptomycin antibiotic, has become highly susceptible to nanoparticles conjugated with streptomycin. • These kinds of study can be extended to other drug resistant bacteria and with different antibiotic and nanoparticles combinations. -- Abstract: A facile one step green synthesis of silver (AgNP), gold (AuNP) and platinum (PtNP) nanoparticles has been attempted using the rind extract of the fruit of Garcinia mangostana L. The rind of the fruit is enriched with wide varieties of natural resources which could be conveniently exploited as alternative for synthesis of nanoparticles eliminating the need for hazardous chemical methods. The formation of gold nanoparticles occurred at room temperature within a few seconds while the formation of silver and platinum nanoparticles was obtained after heating the solution for 20 min at 80 °C. Parameters such as contact time, temperature and pH were optimized to obtain the precise nanoparticles. The green synthesized nanoparticles were characterized using several state-of-the-art techniques like UV–Vis spectroscopic, FT-IR, HR-SEM and HR-TEM, XRD analyses and zeta potential measurements. Attempt has also been made to evaluate the antibacterial activity of the metal nanoparticles before and after combining with commercially used antibiotics as well as free antibiotics against human pathogenic bacteria. The bare silver nanoparticles (AgNP) showed relatively higher antibacterial activity than AuNP and PtNP and this activity was found to be more pronounced against gram negative bacteria than gram positive ones. Interestingly, all the three metal nanoparticles combined with antibiotics showed enhanced antibacterial activity against the pathogenic bacteria which suggested synergism between the nanoparticles and antibiotics. The high point of the present investigation has been that the Bacillus sp. which is highly resistant to streptomycin becomes highly susceptible to the same antibiotic when combined with gold nanoparticles. This particular observation opens up windows for the treatment of antibiotic resistant bacteria after combining with different nanoparticles under clinical set up.

[en] The good quality of the nonlinear optical (4-nitrophenyl) methionine—4NM single organic crystal has been successfully grown using the slow evaporation technique. The lattice parameter, molecular structure and various functional groups of the 4NM grown crystal were confirmed by single-crystal XRD, nuclear magnetic resonance, and Fourier transform infrared spectral analysis, respectively. UV–Vis have identified the range of studies of the optical transmittance spectrum. The thermal stability and melting temperature of the grown crystal were assessed by DSC analysis. The mechanical behaviour of the 4NM crystal is measured by Vickers microhardness and thereby exhibits of reverse indentation effect. Second-harmonic generation using the powder sample Kurtz-Perry technique, the NLO material is effective, and the SHG performance is greater than KDP. The laser damage threshold energy has been measured using Nd: YAG laser (1064 nm). Density functional theory was used to study the natural bond orbital (NBO), Frontier molecular orbitals and molecular electrostatic potential using the B3LYP a method with the 6-311 + +G (d, p) basis set. Furthermore, the hydrogen bonding in the 4NM the molecule was investigated using NBO analysis and the hyper conjugative charge transfer interaction. (author)

[en] The highest proton conductivity value of 0.0802 Scm"−"1 is obtained at 6 wt% of protonated MMT added to the PVA/PEG blends. The polymer blend composite membranes are prepared with varied concentration of Poly vinyl alcohol (PVA), Poly ethylene glycol (PEG) and Montmorillonite (MMT) by solution casting method. The Na"+ MMT was modified (protonated) to H"+ MMT with ion exchange process. The prepared membranes were characterized by using TGA, FTIR, XRD, Ion Exchange Capacity, Water/Methanol uptake, swelling ratio and proton conductivity. The significant improvements in the hydrolytic stability were observed. In addition, thermal stability of the composite membranes were improved and controlled by the addition of MMT. All the prepared membranes are shown appreciable values of proton conductivity at room temperature with 100% relative humidity.

[en] Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV–Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443 nm. The emission spectrum of Ag NPs showed an emission band at 484 nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO_3 against Gram-positive and Gram-negative bacteria. - Highlights: • Microwave irradiation method is used to synthesize silver nanoparticles. • Highly stable silver nanoparticles are produced from serine. • A detailed study of antibacterial activities is discussed. • Formation mechanism of silver microspheres has been proposed