Nilesh V. Gandhare

Evaluation of kinetic parameters from TG/DTG data of chelate polymer compounds of isophthaoyl bis (paramethoxyphenylcarbamide)

The four divalent transition metal chelate polymer compounds such as {[Mn (ibpmpc)(H2O)2] 2H2O}n, {[Co (ibpmpc)(H2O)2] 2H2O}n, {[Ni (ibpmpc)(H2O)2] 3H2O}n and {[Cu (ibpmpc)(H2O)2] 2H2O}n (ibpmpc = isophthaoyl bis (paramethoxyphenylcarbamide) were characterized by thermal properties. The thermal properties like decomposing temperature, thermal stability and presence of hydration water were studied by thermogravimetry (TG), differential thermal gravimetry (DTG) and differential thermal analysis (DTA) and the decomposition steps of these four chelate polymer compounds were investigated. The kinetic and thermodynamic parameters such as the pre-exponential Arrhenius factor (A), order of reaction (n), activation energy (Ea), activation entropy (ΔS#), activation enthalpy (ΔH#) and activation free energy (ΔG#) were calculated using Chen–Liu method. On the basis of thermal analysis technique and thermodynamic kinetic parameter studies, the thermal stability of chelate polymer compounds follows the order Cu (II) > ...

Synthesis, characterization and thermal properties of phthaloyl bis (paramethoxyphenylcarbamide) chelate polymers of divalent transition metals

Seven novel divalent transition metal chelate polymer complexes commonly known as coordination polymers or chelate polymers or coordination complexes such as [Mn (pbpmpc) (H2O)2]n (1), {[Co(pbpmpc) (H2O)2] 4H2O}n (2), {[Ni (pbpmpc) (H2O)2] 2H2O}n (3), {[Cu (pbpmpc) (H2O)2] 1H2O}n (4), {[Zn (pbpmpc)]}n (5), {[Cd (pbpmpc)]}n (6) and {[Hg (pbpmpc)] 1H2O}n (7) were synthesized under an aprotic solvent with phthaloyl bis (paramethoxyphenylcarbamide) (pbpmpc) as a polydentate ligand. The authenticities of these chelate polymers were characterized by elemental analyses: diffuse reflectance spectroscopy, magnetic susceptibility measurements, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermal analyses and scanning electron microscope (SEM) techniques. SEM and XRD investigations significantly revealed a distinct morphology behavior of ligand and chelate polymers. The infrared spectroscopy supports the interaction of nitrogen and oxygen atoms of a polydentate ligand with a metal ion, while diffuse reflectance study is a powerful technique that suggests an octahedral geometry for all the chelate polymers except zinc, cadmium and mercury ions, which were further supported by other instrumental techniques. The decomposition steps and thermal stabilities of these chelate polymers were studied by thermal analysis techniques. The thermal stabilities of chelate polymers were identified on the basis of release of coordinated water and decomposition of backbone structure (ligand).

Copper nanoparticles catalysed an efficient one-pot multicomponents synthesis of chromenes derivatives and its antibacterial activity

ABSTRACT In this study, copper nanoparticles (Cu NPs) were synthesised by using diethylenetriamine as a protective agent in chemical reduction method. The obtained nanoparticles were characterised by various spectroscopic techniques like powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), UV–visible spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal analysis (TG/DTA). The structure and composition were estimated by PXRD, FTIR, EDS, UV–visible and TG/DTA techniques, while particles size and morphology behaviours were investigated by SEM and TEM instrumentation. A noteworthy, average particle size of nanoparticles was found around 40 nm with spherical shapes. Furthermore, the applications part of NPs were studied as a catalyst for one-pot solvent-free green synthesis of 3,4-dihydropyrano[c]chromenes from different aromatic aldehydes, malonitrile and 4-hydroxycoumarin by stirring at 80 °C. Moreover, the antibacterial properties of NPs were assessed in vitro against human bacterial pathogen such as Staphylococcus aureus, Escherichia coli, Klebsiella sp. and Pseudomonas aruginosa using agar well diffusion method. Gram positive bacteria S. aureus (18 mm) exhibited a maximum zone of inhibition at 60 µg/ml of Cu NPs. Nonetheless, antibacterial activities of Cu NPs (10–100 µg) were compared with four well-known antibiotics likes amikacin (30 mcg), ciprofloxacin (5 mcg), gentamicin (5 mcg) and norfloxacin (10 mcg). This study indicates that Cu NPs exhibited a strong antibacterial activity against all the test pathogens even at lower concentration.

An efficient and one-pot synthesis of 2,4,5-trisubstituted imidazole compounds catalyzed by copper nanoparticles

Copper nanoparticles (Cu NPs) were found to be an extremely efficient and effective catalyst for synthesis of 2,4,5-trisubstituted imidazole via three-component reactions of benzil, aldehydes, and ammonium acetate at room temperature. The products obtained were followed by thin-layer chromatography. After completion of the reaction, the reaction mixture was diluted with water (20 mL). The solid imidazole product was washed with water and recrystallized from ethanol to remove nanocopper to afford the pure imidazole compounds. The method provides several advantages such as simple operation, short reaction time, clean reaction profile, lower catalyst loading and high yield. The used catalyst in the reaction could be recovered conveniently and reused for several times. The high yields of reactions are attributed to the effect of Cu NPs due to high surface-to-volume ratio. Due to simple workup procedures, very short times and excellent product yields make this method an interesting alternative to other methodologies.

Oxovanadium (IV) complexes of 2-aryl/heteroaryl-3-hydroxy-4H-chromones: synthesis, spectral and thermal degradation studies

The clinically active functionalized flavonols (2-aryl/heteroaryl-3-hydroxy-4H-chromones) (4a-l) have been synthesized from Algar–Flynn–Oyamada transformation of chalcones (1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-ones). Their oxovanadium metal complexes (5a-l) have been prepared and characterized by physical, spectral, thermal and analytical data. The functionalized flavonol acts as bidentate ligand and coordinates with vanadium metal atom through hydroxyl and carbonyl groups. The complexes have general formula [MOL2], where M = vanadium, O = oxygen and L = ligand. The chelation process reduces the polarity of metal ion by coordinating with ligands, which increase the lipophilic nature of the metals. This lipophilic nature of the metal enhanced its penetration through the lipoid layer of cell membrane of the micro-organism. This constitutes a new group of compounds that can be used as potential metal-derived drugs.

Oxovanadium (IV) complexes with O-O donors ligands: efficient synthesis, spectral characterization, antimicrobial activity and thermal degradation

The clinically active functionalized flavonols (2-aryl/heteroaryl-3-acetoxy-4H-chromones) 5(a-g) were synthesized from Algar–Flynn–Oyamada transformation of chalcones (1-(2-hydroxyphenyl)-3-phenylprop-2-en-1-ones) 4(a-g). Furthermore, oxovanadium metal complexes 6(a-g) of ligands 5(a-g) were synthesized and characterized by physical, Fourier transform infrared (FT-IR) spectroscopy, 1H NMR, mass, UV-reflectance spectroscopy, magnetic moment susceptibility, thermal and analytical data. The functionalized flavonol acts as bidentate chelating ligand and coordinate with vanadium metal atom through hydroxyl and carbonyl groups. The complexes have general formula [MOL2] where M = vanadium, O = oxygen and L = ligand. The chelation process reduces the polarity of metal ion by coordinating with ligands, which increase the lipophilic nature of the metals. This lipophilic nature of the metal enhanced its penetration through the lipoid layer of cell membrane of the micro-organism. This constitutes a new group of compounds that can be used as potential metal derived drugs. Therefore, the synthesized compounds were screen for their antifungal activity against A. niger and C. albicans using the cup plate diffusion method, however antibacterial activities screen against pathogenic bacteria such as E. coli, S. aureus, B. subtilis and P. aeruginosa.

Silica-coated nickel oxide a core-shell nanostructure: synthesis, characterization and its catalytic property in one-pot synthesis of malononitrile derivative

ABSTRACTWe describe herein a unique approach to fabricate the silica-coated nickel oxide a core-shell nanostructure by using a different concentration of surfactant and characterized in terms of shape, size, and phase structure by means of various standard spectroscopic techniques like powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), while chemical composition identified by Fourier transform infrared (FTIR), UV–visible, and thermogravimetry/differential thermal analysis (TG/DTA). The effects of surfactant were authenticated in synthesis of nickel oxide nanoparticles. Furthermore, a simple and straightforward method was employed to synthesis of 2‐oxoindolin‐3‐ylidene malononitrile and their derivatives through Knoevenagel condensation in solvent-free condition using nanoparticle as a nanocatalyst. The derivatives were synthesized with an excellent yield and an eco-friendly. Remarkably, the catalyst was recovered ...

Synthesis, spectral and thermal aspect of transition metal coordination polymers with bis-hydrazone ligand

A few coordination polymeric assemblies of the type {[M(dddinh)(H2O)2].xH2O}n (where M = Mn(II), Ni(II), and Cu(II), x = 2; and Co(II), x = 0, with (N′,N″E,N′,N″E)-N′,N″-(1,2-diphenylethane-1,2diylidene) diisonicotino-hydrazide (dddinh)) have been synthesized and characterized by using various spectroscopic techniques such as elemental analysis, Fourier transform infrared (FTIR), diffuse reflectance spectra, magnetic measurements and thermo gravimetric analysis. Magnetic moment and reflectance spectral studies reveal that an octahedral geometry was assigned to all the prepared coordination polymers. Each metal ion is coordinated by a bis (bidentate) manner through oxygen atom of carbonyl group and the nitrogen atom of amide group of ligand and two aqua ligands by coordinated bond which formed five-member heterocyclic ring. The decomposition steps and thermal stability of these coordination polymers were studied by using thermal analysis techniques. The thermal stabilities of coordination polymers are explained on the basis of release of coordinated water and decomposition of backbone structure (ligand). The thermal studies inferred the presence of crystallized water in all coordination polymers except Co(II), whereas coordinated water was found in all polymers.