Chemistry of a family of semiquinone monochelates of carbonyl ruthenium(II) generated by reacting quinones with hydridic species

The reactions of [Ru(H)(Cl)(CO)(PPh₃)₃] with 3,5-di-tert-butyl-o-benzoquinone (dbq) and 3,4,5,6-tetrachloro-o-benzoquinone (tcq) have afforded the corresponding semiquinone complexes [Ru^II(dbsq)(Cl)(CO)(PPh₃)₂] and [Ru^II(tcsq)(Cl)(CO)(PPh₃)₂], respectively. The reaction of [Ru(H)₂(CO)(PPh₃)₃] with tcq has furnished [Ru^II(tcsq)(H)(CO)(PPh₃)₂]. Structure determination of [Ru(dbsq)(Cl)(CO)(PPh₃)₂] has revealed that it is a model semiquinonoid chelate with two equal C---O lengths ( 1.291(6) and 1.296(6) Å). The complexes are one-electron paramagnetic (1.85μ_B) and their EPR spectra in fluid media display a triplet structure (g2.00) due to superhyperfine coupling with two trans-³¹P atoms (A_iso17 G). The stretching frequency of the CO ligand increases by 20 cm⁻¹ in going from [Ru(dbsq)(Cl)(CO)(PPh₃)₂] to [Ru(tcsq)(Cl)(CO)(PPh₃)₂] consistent with electron withdrawal by chloro substituents. For the same reason the E_1/2 values of the cyclic voltammetric quinone/semiquinone and semiquinone/catechol couples undergo a shift of 500 mV to higher potentials between [Ru(dbsq)(Cl)(CO)(PPh₃)₂] and [Ru(tcsq)(Cl)(CO)(PPh₃)₂].     

Phytosynthesis of Silver Nanoparticle (AgNPs) Using Aqueous Leaf Extract of Knoxia sumatrensis (Retz.) DC. and Their Multi-Potent Biological Activity: An Eco-Friendly Approach

Green synthesis of silver nanoparticles (AgNPs) has gained greater interest among chemists and researchers in this current scenario. The present research investigates the larvicidal and anti-proliferation activity of AgNPs derived from Knoxia sumatrensis aqueous leaf extract (K. sumatrensis-ALE) as a potential capping and reducing candidate. The synthesized AgNPs were characterized through-UV-spectra absorption peak at 425 nm. The XRD and FT-IR studied displayed the crystalline nature and presence of functional groups in prepared samples. FE-SEM showed the hexagonal shape of NPs with the size of 7.73 to 32.84 nm. The synthesized AgNPs displayed superior antioxidant and anti-proliferative activity (IC₅₀ 53.29 µg/mL) of breast cancer cell line (MCF-7). Additionally, larvicidal activity against mosquito vector Culex quinquefasciatus larvae delivered (LC₅₀-0.40, mg/L, and LC₉₀-15.83) significant mortality rate post treatment with synthesized AgNPs. Overall, the present research illustrates that the synthesized AgNPs have high biological potential and present a perfect contender in the pharmacological and mosquitocidal arena.     

Photoconductivity and photo-detecting properties of vacuum deposited ZnSe thin films

The paper reports the detailed analysis of photoconductivity and photo-detecting properties of vacuum deposited zinc selenide (ZnSe) thin films. The vacuum deposited ZnSe films were found to have high absorption coefficient and showed peak photo-response at 460 nm. The photocurrent and photo-response time of the films were measured as a function of substrate temperature and annealing conditions. Considerable increase in photocurrent and much faster photo-response was observed in films deposited at high substrate temperatures. Annealing at moderate temperatures also improved the photoconductivity and response time of the films.     

Formulation and Evaluation of Chitosan‐Gellan Based Methotrexate Implants

An implant controlled‐release system for methotrexate delivery based on a polyion complex composed of chitosan and gellan was investigated. Multi‐layered implant was prepared by using poly(vinyl alcohol), gellan and chitosan. Two chitosan layers sandwiched the poly(vinyl alcohol)‐gellan layer, which acted as a methotrexate reservoir. The prepared implant was evaluated for swellability, in vitro and in vivo release and biodegradation studies. The equilibrium swelling and methotrexate release was found to depend on a concentration of calcium chloride, which was used as a crosslinking agent for gellan. Drug‐loaded implants were subcutaneously implanted in the back of Wistar rats. The in vivo studies showed that methotrexate was released slowly for a period over 30 days and also there was no fibrous capsule formation around the implant indicating the biocompatibility of the implant.     

Compatibility Study of Blends of Acrylic Rubber (ACM), Poly(ethyleneterephalate) (PET), and Liquid Crystalline Polymer (LCP)

The ternary blends of acrylate rubber (ACM), poly(ethyleneterephalate) (PET), and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP, but fixing the ratio of ACM and PET using melt mixing procedure. The compatibility behavior of these blends was investigated with infrared spectroscopy (IR), differential scanning calorimetry (DSC), and dynamic mechanical analyzer (DMA). The IR results revealed the significant interaction between the blend components. Glass transition temperature (T_g) and melting temperature (T_m) of the blends were affected depending on the LCP weight percent in the ACM/PET, respectively. This further suggests the strong interfacial interactions between the blend components. In the presence of ACM, the nucleating effect of LCP was more pronounced for the PET. The thermogravimetric (TGA) study shows the improved thermal stability of the blends.     

Scaling function, anisotropy and the size of RVE in elastic random polycrystals

This article is focused on the identification of the size of the representative volume element (RVE) in linear elastic randomly structured polycrystals made up of cubic single crystals. The RVE is approached by setting up stochastic Dirichlet and Neumann boundary value problems consistent with the Hill(-Mandel) macrohomogeneity condition. Within this framework we introduce a scaling function that relates the single crystal anisotropy to the scale of observation. We derive certain exact characteristics of the scaling function and postulate others based on detailed calculations on copper, lithium, tantalum, magnesium oxide and antimony-yttrium. In deriving the above, we make use of the fact that cubic crystals and polycrystals have a uniquely determined scale-independent bulk modulus. It turns out that the scaling function is exact in the single crystal anisotropy. A methodology to develop a material selection diagram that clearly separates the microscale from the macroscale is proposed. The proposed scaling function not only bridges the length scales but also unifies the treatment of a wide spectrum of cubic crystals. Although the scope of this article is restricted to aggregates made up of cubic-shaped and cubic-symmetry single crystals, the concept of the scaling function can be generalized to other crystal shapes and classes as well as to scaling of other elastic/inelastic properties.