Ultrasound‐Assisted Facile Synthesis and Antimicrobial Studies of Alkanediyl‐bis‐thiazolidin‐4‐ones and Alkanediyl‐bis‐thiazinan‐4‐ones

Alkanediyl‐bis‐2‐aryl‐thiazolidin‐4‐one and alkanediyl‐bis‐2‐aryl‐1,3‐thiazinan‐4‐one derivatives have been congregated in a single step reaction of diaminoalkanes, aryl aldehydes, and sulfanyl acids in the presence of coupling agent N,N′‐dicyclohexylcarbodiimide under ultrasonic conditions. This method of constructing 4‐keto derivatives of thiazolidine and thiazinane is quick and clean besides yielding the products in quantitative yields. The spectral techniques corroborated the structures of the isolated products. Biological assay of the synthesized products has also been reported.     

Green chemistry-assisted synthesis of biocompatible Ag,Cu, and Fe2O3 nanoparticles

Green chemistry-assisted biocompatible copper (Cu), silver (Ag), and iron oxide (Fe₂O₃) nanoparticles (NPs) synthesis along with surface modification using Koelreuteria apiculata is demonstrated in this research, for the first time. Appropriate analytical techniques were utilized to confirm the preparation, spherical morphology, and crystalline structure of each of the NPs. The antioxidant nature of synthesized NPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Besides, the antimicrobial activity was also performed using bacterial strains of Staphylococcus aureus, Escherichia coli, and Salmonella typhi. Aspergillus sp. was designed as marker specie for the antifungal studies. The outcomes of NPs exposure, analyzed with reference to Chlorella sp. of the algal family exhibit the numerical values around 833% for AgNPs, 497% of CuNPs, and 456% for Fe₂O₃NPs. Phytotoxicity assay performed on the seeds of Vigna radiata and Cicer arietinum further validate the accordant nature of NPs towards vivacity. Allium cepa was also used as a test model to ascertain the genotoxic effects of the NPs wherein the mitotic index (MI) was calculated for AgNPs, CuNPs, and Fe₂O₃NPs as 42.1, 51.7, and 54.2% respectively. The outcomes of this research proved the suitability and affordability of our NPs developed using green synthesis for new industrial applications of in-situ reduction of carcinogenic compounds from water and soil.     

Structural elucidation of propargylated products of 3-substituted-1,2,4-triazole-5-thiols by NMR techniques

Propargylation of 3-substituted-1,2,4-triazole-5-thiols, which predominantly exist as their thione tautomers, was carried out with the view to synthesize different heterocycles and study their biological activity. Three different products namely, a mono S-propargyl and two S,N-dipropargyl regioisomers, arising from N1/N2 substitution, were isolated and characterized. Unambiguous structural elucidation of the regioisomers of S,N-dipropargyl derivatives was achieved by means of (13)C-(1)H HMBC technique. The proportion of the regioisomers was found to vary with the substituent on the 1,2,4-triazole thiols. No product corresponding to N4 substitution was isolated from any of the reactions carried out.     

Thermodynamic studies on lithium ferrites

Thermodynamic studies on ternary oxides of Li-Fe-O systems were carried out using differential scanning calorimetry, Knudsen effusion mass spectrometry, and solid-state electrochemical technique based on fluoride electrolyte. Heat capacities of LiFe₅O₈(s) and LiFeO₂(s) were determined in the temperature range 127-861 K using differential scanning calorimetry. Gibbs energies of formation of LiFe₅O₈(s) and LiFeO₂(s) were determined using Knudsen effusion mass spectrometry and solid-state galvanic cell technique. The combined least squares fits can be represented as

Δ_fG_m^o(LiFe₅O₈,s,T)/kJ mol⁻¹ (±6)=−2341+0.6764(T/K) (588≤T/K≤971)     

Synthesis and characterization of some bis(cyclopentadienyl)titanium(IV) complexes with internally functionalized oximes(LH): sol–gel transformations of Cp2TiCl2, Cp2TiClL and Cp2TiL2 to nano‐sized anatase titania

Some bis(cyclopentadienyl)titanium(IV) complexes of the type [Cp₂TiCl_2?n{L}_n] {where, n = 1 or 2; L = ONC(R)Ar; R = H or CH₃ and Ar = C₅H₄N‐2, C₄H₃O‐2 or C₄H₃S‐2} have been synthesized by the metathetical reactions of Cp₂TiCl₂ with the sodium salt of internally functionalized oximes in 1:1 and 1:2 stoichiometry in anhydrous THF. All these red to brown colored solid derivatives have been characterized by elemental analyses, FT‐IR and NMR (¹H and ¹³C{¹H}) spectral studies. The FAB mass spectra of some representative derivatives indicate their monomeric nature. Oximato ligands in all the complexes appear to bind the titanium via N and O in a dihapto ( ‐N, O) manner in the solid state. Thermogravimetric curves of [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] suggest the formation of hybrid materials CpTiO(Cl) and Cp₂TiO, respectively, as the final products at 900 °C under nitrogen atmosphere. Sol–gel transformations of Cp₂TiCl₂, [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] yielded titania a–c, respectively, at low sintering temperature (600 °C). The powder XRD patterns, IR as well as Raman spectra of all these oxides indicate the formation of nano‐sized anatase phase. The SEM images of titania a–c indicate agglomers like surface morphologies. The absorption spectra of a–c exhibit an energy band gap in the range of 3.47–3.71 eV. Copyright © 2011 John Wiley & Sons, Ltd.     

Adsorption of traces of hafnium on manganese dioxide from acid solutions

Adsorption of hafnium on manganese dioxide from nitric and perchloric acid solutions has been studied and optimized with respect to shaking time, concentration of acid, oxide and metal. Maximum adsorption has been noticed from 0.1 mol · dm^–3 acid solutions in 20 minutes around 10^–5 mol · dm^–3 hafnium concentration. The adsorption of hafnium follows a Freundlich adsorption isotherm. Oxalate, thiosulfate, Na(I) and Al(III) from nitric acid and K(I) and Zn(II) from perchloric acid increase the adsorption, whereas all other anions and cations tested reduce the adsorption from both media Fe(III) and Sn(IV) significantly. Zn(II) and Co(II) show low adsorption affinity.     

Development and validation of a high‐performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano‐particulate systems

Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer‐based nanoparticles. Thus, a rapid, highly sensitive method of high‐performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide‐co‐glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed‐phase C₁₈ column using a photodiode array detector at wavelengths of 233 nm (salicylic acid) and 277 nm (folic acid). The mobile phase consisted of acetonitrile–0.1% trifluoroacetic acid mixture programmed for a 30 min gradient elution analysis. In the range of 0.1–100 μg/mL, the assay showed good linearity for salicylic acid (R² = 0.9996) and folic acid (R² = 0.9998). The method demonstrated good reproducibility, intra‐ and inter‐day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01 μg/mL) and quantitation (0.1 and 0.05 μg/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,characterization, and photovoltaic properties of dithienylbenzobisazole‐dithienylsilole copolymers

Three conjugated polymers comprised of dioctyl‐dithieno‐[2,3‐b:2',3'‐d]silole and a donor‐acceptor‐donor triad of either cis‐benzbisoxazole, trans‐benzobisoxazole or trans‐benzobisthiazole were synthesized via the Stille cross‐coupling reaction. The impact of varying the heteroatoms and/or the location within the benzobisazole moiety on the optical and electronic properties of the resulting polymers was evaluated via cyclic voltammetry and UV‐Visible spectroscopy. All of the polymers have similar optical band‐gaps of ～1.9 eV and highest occupied molecular orbital levels of ? 5.2 eV. However, the lowest unoccupied molecular orbitals (LUMO) ranged from ? 3.0 to ? 3.2 eV. Interestingly, when the polymers were used as donor materials in bulk‐heterojunction photovoltaic cells with PC₇₁BM as the electron‐acceptor, the benzobisoxazole‐based polymers gave slightly better results than the benzobisthiazole‐containing polymers with power conversion efficiencies up to 3.5%. These results indicate that benzobisoxazoles are promising materials for use in OPVs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1533–1540     

Photo-switchable azobenzene-functionalized block copolymers from atom transfer radical polymerizations

Diblock copolymers composed of monomers of tert-butyl acrylate and a side-chain azobenzenecontaining monomer, 4-[(E)-(4-nitrophenyl)diazenyl]phenyl prop-2-enoate were synthesized using atom transfer radical polymerization technique. Experimental strategy involved synthesis of block of tert-butyl acrylate macroinitiator followed by addition of second block of azobenzene-containing monomer to prepare desired block-copolymer. GPC analysis indicated narrow molecular weight distributions with degree of polymerization found in good agreement with targeted value. Prepared block copolymers of varying chain lengths can potentially be used to obtain morphologies that can find useful applications for biomedical applications including intriguing photo-switchable drug delivery systems.     

Synthesis and biological evaluation of some new substituted benzoxazepine and benzothiazepine as antipsychotic as well as anticonvulsant agents

Various 2-((2-((5-benzylideneamino)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl) methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (4a–4l), 2-((2-((5-(4-oxo-2-substitutedphenyl thiazolidin-3-yl)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl)methyl)benzo [b] [1,4]oxa/thiazepin-4(5H)-ones (5a–5l) and 2-((2-((5-(3-chloro-2-(substitutedphenyl)-4-oxoazetidin-1-yl)-1,3,4-oxa/thia diazol-2-yl)methyl)hydrazinyl)methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (6a–6l) have been synthesized. The structures of these compounds have been established by elemental (C, H, N) and spectral (IR, ¹H-NMR and Mass) analysis. The synthesized compounds were screened for their antipsychotic and anticonvulsant activities. Compound 5l was found to be the most active compound of this series.