Chemical composition and antimicrobial activity of the inflorescence essential oil of Capillipedium parviflorum (R. Br.) Stapf. from India

Essential oil isolated from the inflorescences of Capillipedium parviflorum (R. Br.) Stapf., collected from Kumaon region of Western Himalaya, India, was investigated by GC and GC-MS. A total of 45 constituents representing 99.0% of the essential oil were identified. The major components of this oil were 4-undecanone (33.2%), 4-undecanol (29.7%), 4-nonanol (13.9%), α-muurolol (5.3%), 4-tridecanone (3.6%), methyl-2-oxo-nonanoate (3.1%), trans-2-hexenyl butanoate (1.1%) and 1-tetradecanol (1.0%). The antimicrobial activity of the essential oil was determined against eight Gram-positive and Gram-negative bacterial strains, as well as two fungal strains. The bioassay showed that the essential oil possessed good antibacterial activity.     

Interaction of naproxen with β-cyclodextrin and its derivatives/polymer: experimental and molecular modeling studies

The interaction of naproxen with β-cyclodextrin and its derivatives (hosts) as well as polymer has been studied using UV Visible (UV–Vis), Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy and Scanning electron microscopy (SEM). In this paper, the solid inclusion complexes were prepared by freeze drying method. The formation constants of the complexes were determined by UV–Vis method. The adsorption properties of naproxen with β-Cyclodextrin bonded silica stationary phase (CDS) were studied for an in-depth understanding of the host–guest interaction. The inclusion process involving naproxen and hosts was investigated by using the PM3 quantum–mechanical semiempirical method. The stabilization energy values obtained from the semiempirical calculation showed the same relation with the formation constant values determined by UV–Vis spectroscopy.     

Palladium complexes of P,P and P,S type bidentate ligands: Implication in Suzuki–Miyaura cross-coupling reaction

New palladium complexes of the type [PdCl₂(η²–P∩P)] (1a,1b) and [PdCl₂(η²–P∩S)] (1c,1d) have been synthesised by the reaction of PdCl₂ with P,P and P,S type bidentate ligands in 1:1 mol ratio, where, P∩P = 9,9–dimethyl-4,5-bis(diphenylphosphanyl) xanthene {Xantphos}(a) or bis(2-diphenylphosphanylphenyl)ether{DPEphos}(b); P∩S = 9,9-dimethyl-4,5-bis(diphenyl -phosphanyl) xanthenemonosulfide {Xantphos(S)}(c) or bis(2-diphenylphosphanyl phenyl) ether monosulfide {DPEphos(S)}(d). The complexes are characterized by elemental analyses, mass spectrometry, ¹H, ¹³C and ³¹P NMR spectroscopy together with the single crystal X-ray structure determination of 1a and 1d. The palladium atom in all the complexes occupies the centre of a slightly distorted square planar environment formed by a P atom, a P/S atom and two Cl atoms. The catalytic activities of 1a–1d investigated for Suzuki–Miyaura cross-coupling reactions at room temperature exhibit higher yield of the coupling products than catalysed by PdCl₂ itself. Among 1a–1d, the palladium complexes of bidentate phosphine (1a, 1b) show higher efficacy than their monosulfide analogues (1c, 1d). However, the recycling experiments with the catalysts for a selected coupling reaction between 4-bromobenzonitrile and phenylboronic acid exhibit that 1c and 1d are more efficient than 1a and 1b, which may be due to the donor effect of the P,S ligands during catalytic reaction.     

Catalyst-free Vicinal bromoazidation of olefins using TMSN3 and NBS

A rapid and efficient method has been developed for the synthesis of vicinal bromoazide directly from olefin using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN₃) as the bromine and azide sources, respectively, without any catalyst in acetonitrile as solvent. The rate of reaction is remarkably fast in acetonitrile without catalyst to produce bromoazides in high yield.     

Broad Dual Emission by Codoping Cr3+ (d→d) and Bi3+ (s→p) in Cs2Ag0.6Na0.4InCl6 Double Perovskite

A phosphor emitting both white light and broad near-infrared (NIR) radiation can simultaneously provide visual inspection and early signs of rotting of food products. The broad NIR emission is absorbed by the vibrational overtones of water molecules present in food items, providing the non-invasive image contrast to assess the food freshness. Here we design a phosphor, namely, Cr³⁺-Bi³⁺-codoped Cs₂Ag_0.6Na_0.4InCl₆, that simultaneously emit warm white light and broad NIR (1000 nm) radiation with quantum yield 27 %. This dual emitter is designed by combining the features of s²-electron (Bi³⁺) and d³-electron (Cr³⁺) doping in a weak crystal field of the halide perovskite host. excitation of Bi³⁺, using a commercial 370 nm ultraviolet light-emitting-diodes (UV-LED), yields both the emissions. A fraction of the excited Bi³⁺ dopants emit the warm white light, and the other fraction transfers its energy non-radiatively to Cr³⁺. Then the Cr³⁺ de-excites emitting broad NIR emission. Temperature dependent (6.4–300 K) photoluminescence in combination with Tanabe-Sugano diagram show that the Cr³⁺ experiences a weak crystal field ( =2.2), yielding the NIR emission. As a proof of concept, we fabricated a panel containing 122 phosphor-converted LEDs, demonstrating its capability to inspect food products.