Azine bridged silver coordination polymers: Powder X-ray diffraction route to crystal structure determination of silver benzotriazole

In continuation of our interest in solid-state structures of silver complexes of photographic importance, the structure for silver benzotriazole (AgBZT), has now been obtained. The preferred method for solving crystal structures is via single-crystal X-ray diffraction (XRD). However, for some materials, growing single crystals of appropriate size and quality is often difficult or even impossible. AgBZT is an example of such a silver complex with poor solubility. The usual routes to preparing single crystals using recrystallization from a cooperating solvent resulted in polycrystalline powder samples. We propose a crystal structure for AgBZT, solved from synchrotron X-ray powder diffraction data, using a direct-space Monte Carlo simulated annealing approach. AgBZT crystals are monoclinic, (P2₁/c), with unit cell dimensions, a=14.8052(3) Å, b=3.7498(4) Å, c=12.3495(12) Å, and β=114.200(6)°. The AgBZT complex is constructed from all three of the Benzotriazole (BZT) nitrogens bonding to a separate silver atom. As a consequence of this bonding mode, the structure is a highly cross-linked, coordination polymer.     

Enhanced ethanol sensing properties of WO3 modified TiO2 nanorods

Pristine and WO₃ decorated TiO₂ nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO₂ NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO₂ NRs and thermally oxidised to obtain WO₃ nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO₂ NRs with WO₃.     

Phenolic compounds,essential oil composition,and antioxidant activity of Angelica purpurascens (Avé-Lall.) Gill

In this study, methanol extracts (MEs) and essential oil (EO) of Angelica purpurascens (Avé-Lall.) Gill obtained from different parts (root, stem, leaf, and seed) were evaluated in terms of antioxidant activity, total phenolics, compositions of phenolic compound, and essential oil with the methods of 2,2-azino-bis(3ethylbenzo-thiazoline-6-sulfonic acid (ABTS•⁺), 2,2-diphenyl-1-picrylhydrazil (DPPH•) radical scavenging activities, and ferric reducing/antioxidant power (FRAP), the Folin–Ciocalteu, liquid chromatography−tandem mass spectrometry (LC−MS/MS), and gas chromatography-mass spectrometry (GC−MS), respectively. The root extract of A. purpurascens exhibited the highest ABTS•⁺, DPPH•, and FRAP activities (IC₅₀: 0.05 ± 0.0001 mg/mL, IC₅₀: 0.06 ± 0.002 mg/mL, 821.04 ± 15.96 µM TEAC (Trolox equivalent antioxidant capacity), respectively). Moreover, EO of A. purpurascens root displayed DPPH• scavenging activity (IC₅₀: 2.95 ± 0.084 mg/mL). The root extract had the highest total phenolic content (438.75 ± 16.39 GAE (gallic acid equivalent), µg/mL)). Twenty compounds were identified by LC−MS/MS. The most abundant phenolics were ferulic acid (244.39 ± 15.64 μg/g extract), benzoic acid (138.18 ± 8.84 μg/g extract), oleuropein (78.04 ± 4.99 μg/g extract), and rutin (31.21 ± 2.00 μg/g extract) in seed, stem, root, and leaf extracts, respectively. According to the GC−MS analysis, the major components were determined as α-bisabolol (22.93%), cubebol (14.39%), α-pinene (11.63%), and α-limonene (9.41%) among 29 compounds. Consequently, the MEs and EO of A. purpurascens can be used as a natural antioxidant source.     

Arm cavity resonant sideband control for laser interferometric gravitational wave detectors

We present a new optical control scheme for a laser interferometric gravitational wave detector that has a high degree of tolerance to interferometer spatial distortions and noise on the input light. The scheme involves resonating the rf sidebands in an interferometer arm cavity.     

A novel approach for solid-liquid extraction laser-excited time-resolved Shpol'skii spectrometry

A new procedure is presented for the analysis of polycyclic aromatic hydrocarbons by solid–liquid extraction (SLE) and laser-excited time-resolved Shpol'skii spectrometry (LETRSS). Microliters of Shpol'skii solvent are spiked on the surface of the extraction membrane and LETRSS is directly performed on the organic layer above the surface of the solid substrate. Fluorescence measurements are easily performed with a fiber-optic cell specifically designed for cryogenic measurements at 77 and 4.2 K. In comparison to the SLE–LETRSS procedure previously reported (Environ. Sci. Technol. 35 (2001) 2566), the spiking procedure eliminates the eluting step, reduces solvent consumption and improves limits of detection for at least one order of magnitude.     

Variable Ag—O bonding patterns in silver cyclic amide tri-aryl-phosphine complexes

The solid-state structures of five new tri-arylphosphine silver cyclic amide complexes having a systematic variation in the ring structures have been resolved. Normal Ag—N bonding and variable, weaker Ag—O bonding interactions, which can be attributed to the ring modifications, form the basis of the bonding patterns. Reported here are the solid-state structures of silver complexes of tri-arylphosphine derivatives of silver 1(2H)-phthalazinone, silver phthalimide, silver 1,2,3-benzotriazin-4(3H)-one, silver 2H-1,3-benzoxazine-2,4(3H)-dione and silver 2,3-dihydro-1,4-phthalazine- dione. The unit cell parameters are: P-1, a = 11.179(2) ?, b = 15.508(3) ?, c = 22.636(5) ?, α = 104.30(3)°, β = 95.39(3)°, γ = 94.62(3)°; C2/c, a = 17.3600(8) ?, b = 15.4930(8) ?, c = 15.0760(7) ?, β = 113.911(2)°; P-1, a = 11.0656(2) ?, b = 11.9447(2) ?, c = 17.4764(3) ?, α = 79.5254(9)°, β = 80.2877(9)°, γ = 68.9136(7)°; P-1, a = 10.5743(4) ?, b = 11.8439(4) ?, c = 19.0110(8) ?, α = 102.4280(13)°, β = 104.0330(12)°, γ = 100.2520(18)°, P-1, a = 13.6908(3) ?, b = 16.2230(4) ?, c = 18.3678(7) ?, α = 86.8920(10)°, β = 69.5290(10)°, γ = 70.7840(10)°, respectively. Four of the complexes include ligand chelation by Ag—O bonding to the adjacent carbonyl in addition to the main Ag—N connection.