Bio-inspired sustainable synthesis of silver chloride nanoparticles and their prominent applications

Advanced nanotechnology is an enormously growing area due to its massive scope of applications for diverse domains of applied science and engineering. Numerous types of synthetic procedures are utilized for the creation of nanoparticles (NPs) due to their myriad application scenarios. However, known conventional physical and chemical strategies have a number of shortcomings. Consequently, the designs of facile, clean, safer, non-noxious, reliable, inexpensive and eco-friendly processes for manufacturing of NPs are being explored actively to circumvent these barriers. The phytogenic fabrication of NPs is much safer, one-pot, facile, and a sustainable methodology. Hence, divergent biological means like the use of plants, biopolymers, fungi, fibres, bacteria, enzymes, etc., are pursued the procurable biogenic fabrication of metallic NPs. In this review paper, current findings on the bio-inspired fabrication of silver chloride nanoparticles (AgCl-NPs) are deliberated, which have with their useful appliances in assorted sectors. The experimental protocols, advanced characterization techniques along with diverse applications of biogenically synthesized AgCl-NPs have been highlighted.     

On the control of n-dimensional thermoelastic system

In this article, we consider n-dimensional thermoelastic system with a nonlinear weak frictional damping. We establish an explicit and general decay rate result, using some properties of the convex functions. Our result is obtained without imposing any restrictive growth assumption on the damping term.     

Crystal Structure of a Trinuclear Mercury(II) Cyanide Complex of Tetramethylthiourea, [{(Tetramethylthiourea)2Hg(CN)2}2·Hg(CN)2]

Abstract  

The title compound was prepared by reacting mercury(II) cyanide and tetramethylthiourea (Tmtu) in the molar ratio of 1:1.75. It was characterized by IR and NMR (¹H and ¹³C) spectroscopy, and X-ray crystallography. The appearance of a band around 2,200 cm⁻¹ in IR and a resonance around 145 ppm in ¹³C NMR indicated the binding of cyanide to mercury(II). The crystal structure of the title complex, [{(tetramethylthiourea)₂Hg(CN)₂}₂·Hg(CN)₂] (1) consists of two independent [(Tmtu)₂Hg(CN)₂] moieties bridged by a Hg(CN)₂ unit. The mercury atom in [(Tmtu)₂Hg(CN)₂] unit is coordinated to two thione sulfur atoms of Tmtu and to two cyanide carbon atoms in a distorted tetrahedral mode.     

Syrian hamster embryo (SHE) assay (pH 6.7) coupled with infrared spectroscopy and chemometrics towards toxicological assessment

The Syrian hamster embryo (SHE) assay (pH 6.7) is an in vitro candidate to replace in vivo carcinogenicity tests. However, the conventional method of visual scoring of foci (non-transformed vs. transformed colonies) can be time-consuming and is open to subjectivity. Infrared (IR) spectroscopy has the potential to provide objective assessment of such SHE colonies with the added advantage of potentially providing mechanistic information. In this study, SHE cells were treated with one of eight different chemical regimens, allowed in culture to attach and form foci on IR-reflective glass slides; these were subsequently interrogated by attenuated total reflection (ATR) Fourier-transform IR (FTIR) spectroscopy. Derived mid-IR spectra (n = 13,406) were subjected to chemometric analysis focusing primarily on the extraction of biochemical information related to test agent treatment and/or morphological transformation. The use of ATR-FTIR spectroscopy with chemometrics to analyze the SHE assay is a novel approach to toxicological assessment.     

Synthesis,characterization and antibacterial activity of palladium(II) bromide complexes of thioamides; X-ray structure of [Pd(tetramethylthiourea)<Subscript>4</Subscript>]Br<Subscript>2</Subscript>

Palladium(II) bromide complexes of thioamides having the general formulae [PdL₂Br₂] and [PdL₄]Br₂ where L = Thiourea (Tu), Methylthiourea (Metu), Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), Imidazolidine-2-thione (Imt), Mercaptopyridine (Mpy), Mercaptopyrimidine (Mpm) and Thionicotinamide (Tna) were prepared by reacting K₂[PdCl₄] with KBr and the corresponding thioamides. The complexes were characterized by elemental analysis, IR and NMR spectroscopy, and one of them, [Pd(Tmtu)₄]Br₂ (1) by X-ray crystallography. The crystal structure of 1 shows a square-planar coordination environment around the Pd(II) atoms with the average cis and trans S–Pd–S bond angles of 90.0° and 180.0°, respectively. The synthesized complexes were screened for antibacterial effects, and the results showed that the complexes exhibit significant activities against both gram positive and gram negative bacteria.     

Voltammetric and spectroscopic investigations of 4-nitrophenylferrocene interacting with DNA

Cyclic voltammetry (CV) coupled with UV–vis and fluorescence spectroscopy were used to probe the interaction of potential anticancer drug, 4-nitrophenylferrocene (NFC) with DNA. The electrostatic interaction of the positively charged NFC with the anionic phosphate of DNA was evidenced by the findings like negative formal potential shift in CV, ionic strength effect, smaller bathochromic shift in UV–vis spectroscopy, incomplete quenching in the emission spectra and decrease in viscosity. The diffusion coefficients of the free and DNA bound forms of the drug were evaluated from Randles–Sevcik equation. The binding parameters like binding constant, ratio of binding constants (K_red/K_ox), binding site size and binding free energy were determined from voltammetric data. The binding constant was also determined from UV–vis and fluorescence spectroscopy with a value quite close to that obtained from CV.     

Electrochemical Investigation of Na‐Salt of 2‐Methyl‐3‐(4‐nitrophenyl)acrylate on Glassy Carbon Electrode

The electrochemical behavior of Na‐salt of 2‐methyl‐3‐(4‐nitrophenyl)acrylate (NPA) and its reduction product was studied by cyclic (CV), differential pulse(DPV) and square wave voltammetry (SWV) using a glassy carbon electrode (GCE). The results revealed that NPA is irreversibly reduced leading to the formation of a reduction product (P_NPA). For pH<9.0 the peak potential was linearly dependent on pH. For pH>9.0 the peak potential was pH‐independent and the value of pK_b≈9.0 was determined. The adsorbed P_NPA exhibited reversible redox reaction. The reduction of P_NPA was pH dependent. To ensure that the electrochemical behavior of NPA is due to the reducible moiety, NO₂, closely related compounds to NPA were also studied, and a redox mechanism was proposed for NPA.     

Dimeric supramolecular motifs of two carboxylate–guanidinium compounds

The structures of N‐benzyl‐N′‐{6‐[(4‐carboxylatobenzyl)aminocarbonyl]‐2‐pyridylmethyl}guanidinium, C₂₃H₂₃N₅O₃, (I), and N‐[2‐(benzylaminocarbonyl)ethyl]‐N′‐{6‐[(4‐carboxylatobenzyl)aminocarbonyl]‐2‐pyridylmethyl}guanidinium monohydrate, C₂₆H₂₈N₆O₄·H₂O, (II), both form three‐dimensional supramolecular hydrogen‐bonded networks based on a dimeric primary synthon involving carboxylate–guanidinium linkages. The differences in the geometries and hydrogen‐bonding connectivities are driven by the additional methylpropionamide group and water of crystallization of (II).     

Titanium-doped sputter-deposited AlN infrared whispering gallery mode microlaser on optical fibers

Optical fibers of 12 μm diameter were coated with a sputter-deposited layer (4 μm thick) of titanium (1 at. %)-doped amorphous aluminum nitride. When optically pumped by an Nd:YAG green laser at 532 nm, laser action was observed in whispering gallery modes around the fiber (in a ring shape) at 780.5 nm with a quality factor Q > 1500. Other modes were also observed between 775 and 800 nm. The primary and secondary modes give a mode separation of 4.6 nm. No waveguide modes were observed in the cavity.