Madhvesh Pathak

An efficient and green La(OTf)3 catalyzed Petasis borono–Mannich reaction for the synthesis of tertiary amines

A variety of tertiary amine derivatives have been prepared by a one-pot three-component Petasis borono–Mannich reaction of two different salicylaldehydes and 2-formylpyridine, substituted morpholine/piperidines and aryl boronic acids. These reactions were carried out under microwave irradiation using a catalytic amount of La(OTf)3 in a short reaction time. This procedure has the advantages of high conversions with excellent chemoselectivity.Graphical AbstractThe attractive features of this methodology are simple procedure, green reaction, reusability and high efficiency of the catalyst and easy workability.

Synthesis, structural, and ε-caprolactone polymerization studies of heteroleptic derivatives of aluminum(III)

A series of metallo-organic complexes of Al(III), [(CH3COCHCOCH3)2Al(OR)]2 [where R = o-MeC6H4 (1), m-MeC6H4 (2), p-MeC6H4 (3), C6H5CH2 (4), o-ClC6H4CH2 (5), m-ClC6H4CH2 (6), and p-ClC6H4CH2 (7), were synthesized quantitatively by treating Al(OPri)3 with CH3COCH2COCH3 and the phenols (o-MeC6H4OH, m-MeC6H4OH, and p-MeC6H4OH) concerned as well as phenylmethanols (C6H5CH2OH, o-ClC6H4CH2OH, m-ClC6H4CH2OH, and p-ClC6H4CH2OH) in suitable stoichiometry using benzene as solvent. All these complexes were soluble in common organic solvents, having sharp melting points, and they were characterized by elemental analysis, IR, and NMR (1H and 13C) spectral studies. Single-crystal XRD followed by ORTEP diagram of solvated complex (1a) revealed its dimeric nature and the existence of six-coordinate aluminum. The complexes were studied in ring-opening polymerization of ε-caprolactone. The molecular weight and polydispersity index values of polycaprolactone were obtained by gel permeation chromatography analysis. Graphical abstract

Spin-Coating Temperature Induced Changes in Ferroelectric Crystallinity in Polyvinylidene Fluoride Ultrathin Films

In the present study, calculated amount of polyvinylidene fluoride (PVDF) was added to a mixture of two different polar solvents and maintained under continuous stirring for overnight. The PVDF solution thus obtained was spin-coated over divergent substrates like KBr and gold coated glass substrates at 80 oC. The spin-coated samples were further exposed to varying thermal conditions such as as-cast (AC), annealed at 130 °C (AN) and melt (200 °C)-slow cooled (MSC) for a period of time. FTIR spectroscopic data obtained from this study was found to be quite useful in analyzing the changes in absorption intensity of crystalline phase changes as a function of varying substrate and heat treatment conditions. Aβ,γ,α/A1073 ratio was observed to be favorable for AN samples when compared to that of AC and MSC samples, and among the substrates, gold is more preferable due to its real-time usage as a substrate in electronic device applications.

Sol-gel combustion synthesis of Ag doped CaSiO3: in vitro bioactivity, antibacterial activity and cytocompatibility studies for biomedical applications

Abstract CaSiO3 is one of the bioactive calcium silicate materials and known as wollastonite. Herewith, for the first time, we have employed sol–gel combustion method to synthesize Ag-doped CaSiO3 using glycine as a fuel. The sintered powders were characterized by ATR-FTIR, XRD and SEM analysis which proved the existence of characteristic functional groups, pure phase formation and flakes, dense morphology with agglomeration, respectively. TEM-SAED analysis confirms that particles are in nano regime with crystalline nature. SBF immersion reveals that pure and Ag-doped CaSiO3 exhibit the good apatite layer formation for 7 and 14 days. Pure and Ag-doped CaSiO3 were evaluated for their antibacterial behaviour against E. coli and S. aureus which reflects the excellent inhibition of microorganisms. MTT assay proves that the prepared 5 wt-% of Ag-doped CaSiO3 exhibits the excellent cellular metabolic activity with MG-63 cells at different concentrations (50–250 μg ml−1) for 24–48 h.

Fluorescent aluminum chelate complexes as modified precursors for nano-structured alumina

Abstract A series of new mononuclear heteroleptic derivatives of aluminum(III), {[(CH3COCHCOCH3)AlL] (1 and 4)}, {[(C6H5COCHCOC6H5)AlL] (2, 5, and 7)}, and {[(C9H6NO)AlL] (3 and 6)}, have been synthesized by reacting Al(OPri)3 with tridentate Schiff base H2Lx (H2L1 = C13H10BrNO2; H2L2 = C14H13NO3; H2L3 = C17H13NO2) and β-diketone/8-hydroxyquinoline (β-diketone = acetylacetone/dibenzoylmethane) in 1 : 1 : 1 stoichiometry using anhydrous benzene and ethanol. All the complexes were characterized by elemental analysis, FTIR, and NMR (1H and 13C) spectral studies. Molecular structures obtained from single-crystal XRD of aqua 1 (1a) and DMSO coordinated 2 (2a) authenticate their existence. Further, nanostructured α-alumina was synthesized from 1 by well-established sol–gel method and was characterized by powder XRD, TEM, and EDX analyses.

Synthetic Studies and Structural Aspects of some Metallacyclic Derivatives of Titanium (IV) - Better Precursors for Titania

Titanium(IV) complexes of the type [(acac)2Ti(O-G-O] and [(acac)2Ti(OCH2CH2SH)2] {where G = (CH2)2, CH2CH(CH3), CH2CH(C2H5), CH(CH3)CH(CH3) have been synthesized in high yield by the interaction of the precursor [(acac)2Ti( OR)2] {where R = Pri , Et} with a variety of glycols and thioglycols in 1:1 and 1:2 molar ratios in refluxing benzene under anhydrous condition yield heteroleptic derivatives. On the basis of physico-chemical analyses, a cis-octahedral environment around Ti (IV) is proposed.