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In the present study, cinnamaldehyde (CNAD) was loaded onto magnetic (Fe3O4) nanoparticles (NPs) that were functionalized with FITC and folic acid (FiCF NPs) for imaging and active drug targeting in breast cancer cells. The particle size of the NPs was ∼10 nm while TGA analysis revealed 20% loading of CNAD onto the NPs. Folic acid conjugation resulted in an increased uptake of NPs in breast cancer cells with their localization in both the cytoplasm and the nucleus. FiCF NPs induced apoptosis in the cells and increased the expression of generic caspases. Acute toxicity study demonstrated safety of the NPs in Swiss albino mice. Interestingly, FiCF NPs reduced the tumor burden in the mouse breast cancer model compared to those treated with free CNAD and FiC functionalized NPs. Furthermore, pharmacokinetic studies in Wistar rats revealed prolonged circulation time and slower plasma elimination of CNAD in animals treated with FiCF NPs. Thus, FiCF NPs exhibited promising potential against breast cancer and warrant further safety studies in the future before exploring their potential at the clinical level.

A non-noble metal-based bifunctional Fe–Ni/MMT nanocomposites exhibit excellent H2 generation capability from the methanolysis of NaBH4 at a rate of 16,200 mL min−1 g−1Fe–Ni with 10%Fe–Ni loading on MMT support. Moreover, the evolved H2 from this catalytic process is efficiently utilized for the one-pot step-wise synthesis of secondary amines from nitrobenzene and aldehydes using NaBH4 as a source of hydrogen at room temperature. Circumventing the reduction of aldehyde and triggering the formation of imine intermediate through sequential addition of reactants in a time dependent manner has resulted in the excellent yields for aliphatic, aromatic and heterocyclic amines (91–98%). The catalytic activity of Fe–Ni/MMT nanocomposite is ascribed to synergic association of Fe–Ni NPs, Lewis and Bronsted acidity as well as adsorptive nature of MMT. Thus, a simple, facile and greener route is developed for the synthesis of secondary amines with an efficient H2 generation non-noble metal catalyst and easily accessible H-donor at room temperature.

Nanoceria is considered to be a promising material for the modulation of its pro-and anti-oxidant activities due to its tuneable Ce3+/Ce4+ ratios under different physiological conditions. In the present study, we explored the feasibility of CeO2 NPs as a pro-drug and drug carrying vehicle towards receptor-mediated targeted delivery of doxorubicin (DOX) to MCF-7 cancer cells. The surface-engineered, substancilly smaller sized (3–4 nm) particles of CeO2-loaded DOX-nanoconjugates possess excellent dispersibility in water, with surface charges in the range of +17.03 to −7.68 mV. The functionalised nanoceria exhibits a quasi-reversible Ce3+/Ce4+ redox couple at a considerably lower redox potential, while the amount of DOX loaded on the nanoceria was found to be in the range of 2.3–12%. The DNA binding and cleavage activities of CeO2 NPs suggest their beneficial binding with phosphate linkages that induces DNA damage. Uncoated and PEGylated CeO2 NPs possess significant anticancer activity against MCF-7, with the latter exhibiting better activity at 2.5 μg mL−1 due to its interference in cellular redox reactions induced by reactive oxygen species (ROS). Moreover, the synergic conjugation of nanoceria with DOX resulted in excellent cytotoxicity of these nanoconjugates against MCF-7 cells at an extremely low concentration (57.5 ng mL−1) of DOX. This feature can be ascribed to the enhanced uptake of nanoceria as well as site targeting of DOX nanoconjugates facilitated by the folic acid (FA) via folate receptors. Thus, it may be concluded that nanoceria behaves in a dual manner both as a pro-drug and an efficient nanocarrier for delivery of DOX at a specific site.

The hydrazones of nonsteroidal anti-inflammatory drugs (NSAIDs) diclofenac and ibuprofen are synthesized with aldehydes of pyridine and imidazole and are characterized by 1H, 13C and mass spectroscopy. Cu(II) complexes of hydrazones constructed from these ligands possess square planar geometry for bidentate diclofenac-hydrazone and tridentate ibuprofen-hydrazone conjugates with [Cu(L)2] and [Cu(L)Cl] compositions, respectively. The observed irreversible Cu(II)/Cu(I) redox couple in the range of +0.20 to +0.61 V is due to the substantial distortion in the square-planar geometry. ESR studies indicate the appreciably covalent character within M–L bonding due to extensive delocalization of electron from dx2–-y2 orbital. The hydrazone–NSAID conjugates exhibit substantial cytotoxicity against A-549, HCT-116 and MDA-MB-231 cancer cell lines with ibuprofen-imidazole-hydrazone ligand possessing the lowest IC50 (2.26 µM) amongst the synthesized NSAID-conjugates. Interestingly, its Cu(II) complex also displays excellent anticancer activity against MDA-MB- 231 with IC50 value of 3.58 µM. Such a feature may be ascribed to the synergistic association of Cu(II)–NSAID–hydrazone linkage. Thus, conjugation of NSAID with hydrazone and its complexation with a bioactive metal ion may be regarded as a potential strategy for designing of non-platinum anticancer agents.

A simple, facile, and convenient route is adopted for the synthesis of 4,9-dimethoxynaphthalide (4,9-DMN); an analog of naturally occurring naphthalene lactone family. It is achieved without involving a tedious and hazardous lithiation step using 3-(bromomethyl)-1,4-dimethoxy-2-naphthaldehyde as key intermediate through base catalyzed oxidative cyclization resulting in a five-membered lactone ring. This compound exhibits significant anti-fungal activity against Candida albicans while it is found to be less toxic towards MCF-7 cancer cell line with IC50 value less than 250 µM.

Direct one-pot hydrogenation of furfural (FFR) to cyclopentanone (CPO) was investigated over different silica-supported Pd catalysts. Among these, 4% Pd on fumed silica (4%Pd/f-SiO2) showed remarkable results, achieving almost 98% furfural (FFR) conversion with ∼89% selectivity and 87% yield to cyclopentanone at 165 °C and 500 psig H2 pressure. More interestingly, the fumed-silica-supported catalyst tuned the selectivity toward the rearrangement product, i.e., cyclopentanone, whereas all of the other supports were found to give ring hydrogenation as well as side chain hydrogenation products due to their parent Brönsted acidity and specific support properties. X-ray diffraction data revealed the presence of different phases of the face-centered cubic lattice of metallic Pd along with lowest crystallite size of 15.6 nm in the case of the silica-supported Pd catalyst. However, Pd particle size was found to be in the range of 5–13 nm with even dispersion over the silica support, confirmed by high-resolution transmission electron microscopy analysis. While studying the effect of reaction parameters, it was observed that lower temperature gave low furfural conversion of 58% with only 51% CPO selectivity. Similarly, higher H2 pressure lowered CPO selectivity with subsequent increase in 2-methyl furan and ring hydrogenation product 2-methyl furan and 2-methyl tetrahydrofuran. Thus, as per the requirement, the product selectivity can be tuned by varying the type of support and/or the reaction parameters suitably. With the help of several control experiments and the characterization data, a plausible reaction pathway was proposed for the selective formation of cyclopentanone.

The acid functionality of montmorillonite clay K 10 (MMT-K 10) was found to play a key role to give 1,2-pentanediol (1,2-PeDO) in Pd catalysed furfural hydrogenation. Among various Pd loadings on MMT-K 10, 3% Pd/MMT-K 10 catalyst exhibited excellent performance giving almost complete conversion of FFR and the highest selectivity of 66% to 1,2-PeDO. Py-IR of the catalyst evidenced the presence of Bronsted acidity which was responsible in C5-O cleavage of furan ring after the formation of furfuryl alcohol which is the first step intermediate in FFR hydrogenation. At a lower temperature of 140 °C, highest selectivity of 56% was achieved for FAL while increase in temperature to 220 °C, enhanced the selectivity to 1,2-PeDO. Keeping the temperature constant at 220 °C, increase in H 2 pressure from 500 to 750 psig, resulted in decrease in 1,2-PeDO selectivity from 66 to 34% with proportionate increase in THFAL selectivity. Thus as per the requirement, the product selectivities can be tailored by varying the reaction parameters suitably. Several control experiments were also performed the results of which combined with the characterization data allowed to propose a plausible reaction pathway for the formation of 1,2-PeDO.

Dihydrobenzofuran as one of the active ingredients of the naturally occurring motif is synthesized by using in situ generation of ortho allyl phenols. Aryl allyl ethers on reacting with catalytic amounts of non noble metal iron (III) chloride supported on MCM-41 under moderate reaction conditions yield dihydrobenzofuran. First step via Claisen rearrangement gives ortho allyl phenol followed by its in situ cyclization to yield dihydrobenzofuran in very good yields. Both Lewis as well as Brønsted acidity of the catalyst as evidenced by Py-FTIR studies was found to catalyze the cascade synthesis of dihydrobenzofuran. The scope of the present strategy was successfully demonstrated for several substrates with varying electronic effects for the synthesis of corresponding dihydrobenzofuran with high yields in a range of 71–86%. Keywords: Claisen rearrangement, Dihydrobenzofuran, Aryl allyl ether, MCM-41, Ferric chloride

Various iridium supported carbon catalysts were prepared and screened for the direct hydrogenation of furfural (FFR) to 2-methyl furan (2-MF). Amongst these, 5% Ir/C showed excellent results with complete FFR conversion and highest selectivity of 95% to 2-MF at a very low H2 pressure of 100 psig. Metallic (Ir°) and oxide (IrO2) phases of Ir catalyzed the first step hydrogenation involving FFR to FAL and subsequent hydrogenation to 2-MF, respectively. This was confirmed by XPS analysis and some control experiments. At a low temperature of 140 °C, almost equal selectivities of FAL (42%) and 2-MF (43%) were observed, while the higher temperature (220 °C) favored selective hydrodeoxygenation. At optimized temperature, 2-MF was formed selectively while higher pressure and higher catalyst loading favored ring hydrogenation of furfural rather than side chain hydrogenation. With the combination of several control experimental results and detailed catalyst characterization, a plausible reaction pathway has been proposed for the selective formation of 2-MF. The selectivity to various other products in FFR hydrogenation can be manipulated by tailoring the reaction conditions over the same catalyst.

Present study illustrates the significant enhancement in the adsorption capacity of glutaraldehyde cross-linked chitosan (C) films through immobilization of 1,5-diphenyl carbazide (D) towards Cr(VI). TGA studies reveal incorporation of about 11% D within the pores of the film while FESEM analysis further confirm thread like nature containing hydrophobic voids. Contact angle measurements suggest the appropriate balance of hydrophilic/hydrophobic nature of film through successive modifications with glutaraldehyde (G) and D. It is observed that Cr(VI) uptake by films is substantially improved by about 25% at pH 2 that follows pseudo first order kinetics with a rate constant value of 0.085 h − 1 . Adsorption studies suggest that removal of Cr(VI) is a spontaneous process occurring mainly through pore diffusion process with removal capacity of 166 mg g − 1 . XPS analysis of Cr(VI) treated C + G + D film indicate formation of Cr-D complex on the surface of film as well as presence of predominantly adsorbed Cr(III) species. It is interesting to note that there exists strong binding of Cr(III) with D present within the pores of film in a quantitative manner. Thus, it can be argued that incorporation of a selective chelating agent like D has substantial effect on removal efficiency of C + G + D for Cr(VI); an approach possessing potential applications in membrane technology.

Contamination of water and soil with Pharmaceutical and Personal Care Products (PPCP); although present at very lower concentrations, has raised alarming issues regarding their toxicity to ecosystem. Their mitigation through biological and chemical treatments have been a area of great interest in recent past. One such attempt is made wherein degradation of doxorubicin (DOX); a well known anticancer agent, is explored with Fe-Ni bimetallic nanoparticles (Fe-Ni NP’s). These nanoparticles degrade DOX through chemisorptive exothermic pseudo-multilayer film-diffusion mineralisation process as evident from adsorption and intra-particle mechanisms. The degradation mechanism is established from metabolites formed during its degradation by LC–MS analysis. It is observed that chemical degradation route closely resembles with that of metabolic pathway mediated by aldo-keto reductase (AKR); a family of oxido-reductase enzyme involving ROS and iron-sulphur clusters. The toxicity of degraded DOX solution evaluated against two breast cancer cell lines viz. MCF-7 and MDA-MB-231 and a normal cell line HEK-293 revealed that the metabolites are non-toxic in nature. These findings are further corroborated with chemo-informatics studies using Molinspiration Properties Calculator. Formation of oxide layer on the nanoparticle surface evident from XPS analysis that decreases their recycling capacity. Thus, Fe-Ni NP’s are exhibiting properties like a functional mimic of AKR that degrade DOX in an eco-friendly manner.

The present work describes the improved photocatalytic activity of cetyl trimethylammonium bromide (CTAB)-assisted Bi2WO6 (CBTH) toward the synthesis of bioactive benzazoles. X-ray diffraction analysis of CBTH suggests that crystal growth has occurred along the (200) plane, whereas field-emission scanning electron microscopy images confirm two-dimensional rose bud morphology and high-resolution transmission electron microscopy analysis suggests the formation of thin nanosheets possessing an orthorhombic structure. Temperature-programmed desorption of ammonia and Py-IR measurements indicate substantial acidity with the generation of Brønsted acid sites on the surface of CBTH. Raman spectra of CBTH also corroborate these observations with the formation of defects within [Bi2O2]2+ layers, resulting in decreased thickness and shapes of nanoplates. These beneficial properties are explored toward the photochemical synthesis of benzazoles using a 35 W tungsten lamp and a CBTH photocatalyst, resulting in better yields at lesser exposure time. It is observed that the catalytic activity is retained up to five consecutive cycles with marginal decrease in % yield. Such a feature can be ascribed to the photostability of the photocatalyst even after continuous exposure to light, implying that the surface active sites remained unaltered as evident from the X-ray photoelectron spectroscopy analysis of pre- and post-characterization of CBTH. Moreover, decrease in the surface hydroxyl groups after five catalytic cycles also accounts for the generation of enhanced Brønsted sites owing to the presence of Bi–O on the surface of CBTH. It exhibits better catalytic activity as compared to other photocatalysts employed for the synthesis of benzazoles. Thus, CBTH serves as a robust photocatalyst for the facile synthesis of these heterocycles in a sustainable manner.

Four Ru(II) complexes with tridentate ligands viz. (4-hydroxy-N′-(pyridin-2-yl-ethylene) benzohydrazide [Ru(L1)(PPh3)2(Cl)] (1), N′-(pyridin-2-yl-methylene) nicotinohydrazide [Ru(L2)(PPh3)2(Cl)] (2), N′-(1H-imidazol-2-yl-methylene)-4-hydroxybenzohydrazide [Ru(L3)(PPh3)2(Cl)] (3), and N′-(1H-imidazol-2-yl-methylene) nicotinohydrazide [Ru(L4)(PPh3)2(Cl)] (4) have been synthesized and characterized. The methoxy-derivative of L3H (abbreviated as L3H*) exists in E configuration with torsional angle of 179.4° around C7-N8-N9-C10 linkage. Single crystal structures of acetonitrile coordinated ruthenium complexes of 1 and 3 having compositins as [Ru(L1)(PPh3)2(CH3CN)]Cl (1a) and [Ru(L3)(PPh3)2(CH3CN)]Cl (3a) revealed coordination of tridentate ligands with significantly distorted octahedral geometry constructed by imine nitrogen, heterocyclic nitrogen, and enolate amide oxygen, forming a cis-planar ring with trans-placement of two PPh3 groups and a coordinated acetonitrile. Ligands (L1H-L4H) and their ruth...

Single step conversion of furfural to ring hydrogenation and decarbonylation products, 2-methyltetrahydrofuran (2-MeTHF) and tetrahydrofuran (THF) in high selectivity was achieved by controlling the particle size of Pd/C catalyst. The particle size variation of Pd/C catalysts in the range of 3.8 to 22 nm could be achieved by employing different reducing agents. Of particular interest was the NaBH4 reduced catalyst (Pd−B/C), which gave the lowest crystallite size of 4.8 nm due to incorporation of B into the inner lattices of Pd−Pd. This phase was evidenced by a characteristic XRD peak of Pd−B at 2θ=38.85 O as well as a shift of (111) peak (40.07 O) of Pd towards the lower value (39.8 O). As compared to formaldehyde reduced catalyst (Pd−F/C), Pd−B/C catalyst completely suppressed the formation of furfuryl alcohol to give > 65 % selectivity to 2-MeTHF and THF. At 180 OC, almost equal distribution of side chain hydrogenation and ring opening products, 2-MF (45 %) and PeDO (37 %), respectively, was observed while, higher temperature clearly favoured ring hydrogenation and decarbonylation reactions to give 2-MeTHF and THF.

Removal of the protecting allyl group from allyl aryl ethers in the presence of other oxygen protecting groups was successfully achieved using a solid acid supported on the high surface area material MCM-41. The catalyst showed excellent activity in the presence of various electron withdrawing, electron donating, and oxidizable functional groups. The methodology is also very useful for the removal of protecting allyl groups of various natural products such as vanillin, isovanillin, and other oxygen functionalized aldehydes and ketones.

Bimetallic nanoparticles have diverse applications in catalytic processes owing to the differences in individual properties that contribute to their increased catalytic activity. To further improve the efficiency, they are dispersed in an inert support that enhances the catalytic activity toward organic transformations. In this study, we report simple, facile, and cost-effective chemical route for the fabrication of nanocomposites with Fe–Ni bimetallic nanoparticles supported on montmorillonite (MMT) possessing variation in the Fe and Ni content. These composites are characterized with X-ray diffraction, transmission electron microscopy surface area, and NH3-TPD. Fe–Ni bimetallic nanoparticles are well-dispersed within MMT structure having particle sizes of about 30–40 nm. Among various compositions of Fe–Ni/MMT catalysts, composite with 25% Fe and 25% Ni exhibits >99% LA conversion with 98% selectivity to GVL within 1 h. IPA is found to be better solvent for levulinic acid (LA) to γ-valerolactone (GVL) c...

A facile, one-pot three component catalytic method is developed for the synthesis of N-substituted tetrazole using RuO2/MMT nanocomposite. It is characterized with low and wide angle XRD which suggests that RuO2 nanoparticles are evenly dispersed on the surface of MMT while FESEM images indicate a spherical morphology having size in the range of 40-50 nm. The catalytic efficiency is evaluated for three component one-pot synthesis of the tetrazole using various amine, sodium azide and triethyl-ortho-formate under solvent free condition. This strategy has resulted in good to excellent yields (84 – 97%) of N-substituted tetrazoles within moderate reaction time. Moreover, the catalyst possesses excellent reusability up to five cycles with only 5% decrease in the yield of tetrazole after 5th cycle. The beneficial catalytic activity of the bifunctional nanocomposite is attributed to the uniformly dispersed RuO2 nanoparticles on the surface of MMT where RuO2 site is responsible for coordination of isocyanide intermediate while strong acidic character of MMT induces condensation and cyclization steps in a synergic manner. Thus, it can be argued that RuO2/MMT nanocomposite possesses potential applications for Multi Component Reactions (MCR) in terms of efficient and sustainable manner.

The humidity sensing properties of Ni1−xMgxYyFe2−yO4 (x = 0, 0.1 and 0.3 when y = 0; and y = 0.1 and 0.3 when x = 0.3) thick films are investigated. The structural and morphological properties of the resulting materials were determined by XRD, TEM, SEM and BET techniques. These revealed materials of polycrystalline nature with a single phase spinel structure possessing porosity having cubic and spherical shape morphology. XPS analysis suggested that the presence of Y3+ on the surface enhances the humidity sensing properties. Thick films exhibit better sensing properties as compared to pellets at lower relative humidity with less hysteresis characteristics at a lower film thickness. Faster response and recovery time are observed for thick films due to the formation of a uniform layer of active sites on the film surface. The long-term stability is evaluated over a period of six months when it is noticed that the response remains almost constant at different ranges of humidity. This feature may be regarded as a significant facet towards their practical application as humidity sensors.

A sustainable process of catalytic transfer hydrogenation (CTH) of levulinic acid (LA) to γ-valerolactone (GVL) was investigated over Ni on various supports (Al2O3, ZnO, MMT and SiO2) in the presence of isopropanol (IPA) as the H-donor. Among these, the montmorillonite (MMT) supported Ni catalyst showed almost complete LA conversion (>99%) and selectivity (>99%) to GVL within 1 h. XRD and XPS results showed that the concentration of the metallic species significantly enhanced (two to four times) in the recovered sample as compared to the freshly prepared Ni/MMT. This was due to the in situ reduction of Ni2+ species present on the catalyst surface, through liberated H2 under the reaction conditions. The strong acid strength of MMT, evidenced by NH3-TPD and py-IR, facilitated the esterification of LA as well as cyclization to GVL. The conversion–selectivity pattern was found to decrease in the IPA–water mixture while, it remained unchanged in the IPA–acetone mixture. Our catalyst could be efficiently recycled up to five times with consistent CTH activity and selectivity to GVL. The plausible mechanism of LA to GVL conversion involves the formation of a levulinate ester with IPA that favours its simultaneous hydrogenation and cyclization in a spontaneous manner to give GVL and regenerating IPA for sustainability.

In this paper, we have developed an efficient electrostatic self-assembly strategy for the synthesis of a CdSe–CTAB–MMT composite that contains well-dispersed CdSe quantum dots (CdSe QDs) within the MMT structure. These nanocomposites are characterised by XRD, TEM, Raman, DRS and photoluminescence studies which indicate that 3–5 nm sized CdSe QDs are intercalated within lamellar sheets of MMT. Visible light induced photocatalytic activities of the composites exhibit decolourisation of Indigo Carmine (IC) solution (100 mg L−1) within 30 min. at 1.0 g L−1 catalyst loading. This feature is attributed to separation of photogenerated electron–hole pairs, enhanced interlayer spacing (7.2 A°), higher specific surface area and better adsorption capacity of the MMT. The involvement of reactive oxygen species (ROS) in the photodegradation process is ascertained by addition of selective quenchers such as NaN3 (for singlet oxygen), benzoquinone (for O2˙−), ascorbic acid (for OH˙) and KI (for h+). It is observed that singlet oxygen and photogenerated h+ do not contribute towards degradation; rather O2˙− is a prominent species that degrades ∼74% of IC while the remaining part is oxidized by OH˙. The photodegradation pathway involves desulphonation of IC followed by its oxidation to isatin, anthranilic acid, tryptanthrin and isatoic anhydride. The antibacterial studies of degraded IC solution as well as chemoinformatics studies suggest that these metabolites are non-toxic in nature. These catalysts remain active for up to 6 cycles with a marginal decrease in their removal capacity that can be ascribed to inhibition of photocorrosion even after successive exposure to light. Thus, nano-engineered CdSe-composites may be regarded as efficient photocatalysts that have potential applications in sustainable development towards continuous removal of organic dyes from aqueous streams.

The reductive removal of Cr(VI) is investigated with zero-valent iron, Fe–Ni bimetallic nanoparticles and Fe–Ni bimetallic-montmorillonite nanocomposites. XRD and TEM studies reveal generation of active sites on nanocomposites possessing increased surface area.The removal of Cr(VI) follows pseudo-second order rate model with 2 g L −1 composite loading with sorption capacity ( q e ) in the range of 30–50 mg g −1 for the composites. Employing adsorption isotherms like Langmuir, Freundlich, Redlich–Peterson, Dubinin–Radushkevich (D–R), Temkin and Flory–Huggins (F–H), it is observed that adsorption process essentially follows pseudo-multilayer exothermic chemisorption process with free energy of adsorption (DG°) in the range of −10 to −15 KJ mol −1 . Pore diffusion is predominant as compared to film diffusion process; evaluated from intra-particle diffusion models, augurs well for stronger ionic interactions between Cr(VI) ions and adsorbents. The improved efficiency of composites may be attributed to the large number of available surface Fe 0 atoms that significantly contributes towards reduction of adsorbed Cr(VI) on the surface. XPS measurements of composites after last cycle clearly establish the fact that formation of surface hydroxides mediates efficient flow of electron from bulk to Cr(VI) suggesting their potential usage for continuous removal capabilities.

The degradation of a basic magenta (BM) from aqueous streams is explored to ascertain the role of dissolve oxygen using Fe-Ni bimetallic nanocomposites as catalyst. XRD analysis of Fe-Ni bimetallic nanocomposites prepared with montmorillonite (MMT) clay suggested its intercalation with Fe-Ni bimetallic nanoparticles whereas TEM images indicated the spherical nature with 20–40 nm. Batch experiments containing 100 mg L−1 dye solution and 1 g L−1 catalyst exhibited complete decolorization of BM within 10 min following first order reaction kinetics. Amongst the nanocomposites, 10% loaded and 50% in situ compositions possess better activity with enhanced degradation capacity below pH 4 because of generation of reactive H• species. LC-MS analysis of decolorized solution revealed the formation of both reductive and oxidative metabolites with prominence of N-demethylated species mainly due to both H− ions and •OH radicals. Moreover, when the deaerated solution of BM (N2 purged dye solution) is subjected for catalytic treatment, only 17% decolorization is observed that further vouch for effectiveness of dissolved oxygen on the degradation process. To ascertain this hypothesis, sodium azide, a selective quencher for singlet oxygen, is added to the dye solution and the supernatant thus obtained is subjected for LC-MS analysis. This study clearly establishes the fact that reactive oxygenated species (ROS) indeed influence the course of degradation for organic pollutants and this technology may be regarded as aerobic degradation process mediated by zerovalent metal based nanocomposites as efficient catalyst. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 615–623, 2013

Removal of phenol employing ZnO–bentonite nanocomposite as photocatalyst with UV irradiations is evaluated under Continuous Stirred Tank Reactor (CSTR). XRD patterns of nanocomposites indicated modifications in the lattice structure of bentonite due to intercalation of ZnO nanospheres in the matrix with particles size of 20–30 nm as revealed from TEM. Thin film of composites coated on SS plate surface exhibited ∼70% removal of phenol from the simulated effluent under at lower flow rate (10 ml min−1) and higher pH (12) at a fixed nanocomposite loading. The effluent obtained after CSTR treatment is analyzed by LC–MS which suggested that photocatalytic degradation of phenol results in the formation of adipic acid and 2,4,6-triphenoxy phenol through radical mechanism.

The remediation of Cr(VI) from simulated water streams is investigated using Fe–Ni bimetallic nanoparticles (Fe–Ni NPs) and their nanocomposites prepared with montmorillonite (MMT) clay. These nanocomposites are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyses. XRD analysis revealed proper dispersion as well as intercalation of Fe–Ni NPs in the clay matrix. TEM of nanocomposites showed the presence of spherical particles having a size of 20–40 nm. Batch experiments with a 25 mg L−1 Cr(VI) solution and 2 g L−1 Fe–Ni NPs exhibited complete reduction of Cr(VI) within 10 min that follows first order reaction kinetics. Amongst 25%, 50%, 75% in situ and loaded nanocomposites, 75% compositions possess better activity with enhanced reduction capacity below pH 4 due to generation of reactive H species. XPS analysis of nanocomposites after Cr(VI) treatment suggested that reduction process occurs through Cr(III) formation followed by its subsequent reduction to Cr(0). Their potentiality towards reusage is established from the recycling experiments that revealed the order of efficiency as 75% in situ > Fe–Ni NPs > 75% loaded nanocomposites.

Nanoscale Fe–Pd bimetallic particles were synthesized and used for degradation of lindane (γ-hexachlorocyclohexane) in aqueous solution. Batch studies showed that 5 mg/L of lindane was completely dechlorinated within 5 min at a catalyst loading of 0.5 g/L and the degradation process followed first-order kinetics. GC–MS analysis in corroboration with GC-ECD results showed the presence of cyclohexane as the final degradation product. The proposed mechanism for the reductive dechlorination of lindane involves Fe corrosion-induced hydrogen atom transfer from the Pd surface. The enhanced degradation efficiency of Fe–Pd nanoparticles is attributed to: (1) high specific surface area of the nanoscale metal particles (60 m 2 /g), manyfold greater that of commercial grade micro- or milli-scale iron particles (∼1.6 m 2 /g); and, (2) increased catalytic reactivity due to the presence of Pd on the surface. Recycling and column studies showed that these nanoparticles exhibit efficient and sustained catalytic activity.

The effects of acidity and variation in concentration of acid sites of dodecatungstophosphoric acid (DTP), supported DTP and montmorillonite-K catalysts were studied for various organic reactions such as the hydroxyalkylation of phenols to bisphenols, intramolecular rearrangement of benzyl phenyl ether (BPE) to 2-benzyl phenol (2-BP) and selective cleavage of tert-butyldimethylsilyl (TBDMS) ether into the corresponding alcohol. Both dodecatungstophosphoric acid (DTP) impregnated on silica (SiO2) and montmorillonite catalysts showed the highest catalyst activity with 90–95% selectivity to bisphenol for the hydroxyalkylation of phenols to give bisphenol. Temperature Programmed Desorption (TPD) of ammonia and activity results of various catalysts showed that an appropriate combination of both strong and weak acidic sites in the catalyst was highly desirable for high bisphenol selectivity. A 10% DTP/SiO2 catalyst was found to be highly selective for the cleavage of TBDMS ether into the corresponding alcohol at room temperature giving a high TON of 9.5 × 105 even after the 4th recycle. DTP was also found to be a promising solid acid catalyst for the intramolecular rearrangement of BPE giving 2-BP.

The synthesis of capped α-Fe 2 O 3 nanoparticles from thermal treatment of iron (III) hydroxy-oleate in boiling organic solvents around 250 °C with retention of the integrity of the oleate units during the reaction process is reported. The formation of capped iron oxide particles is accomplished under aerobic conditions while the solvents used in the synthesis have strong influence on the nature and morphology of nanoparticles. These nanoparticles are studied by means of X-ray powder diffraction, IR and XPS while the morphology and particle size of nanocrystals are evaluated using SEM and TEM analysis suggesting the formation of monocrystalline α-Fe 2 O 3 particles having cubical and spherical morphologies with sizes ranging from 20 to 30 nm. This organophilic material with oleate capping around the surfaces can be readily dispersed in organic solvents thus forming organosols. These organosols exhibit band-edge emission photoluminescence band both in toluene as well as in solid state while FT-IR analysis reveals formation oleate capped nanoparticles The XPS data indicate ferric state having doublet from Fe 2p 3/2 and Fe 2p 1/2 core-level electrons.

A simple chemical route is developed to generate maghemite (γ-Fe2O3) nano-particles, dispersed in organic solvents via a thermal decomposition of an iron–hydroxy oleate precursor. An iron–hydroxy oleate precursor was generated by chemical reaction of mixed iron nitrate and oleic acid in ethanol with 30% NH3 solution with continuous stirring at room temperature. The precursor thus obtained was suspended in hexadecane and then mixed with necessary quantity of oleic acid at room temperature with constant stirring and is further heated to 220 °C/2 h to convert it in to γ-Fe2O3 nano-particles. The mixture is allowed to cool slowly to room temperature. The γ-Fe2O3 nano-particles remained in dispersed state in hexadecane. The iron–hydroxy oleate molecular precursor and γ-Fe2O3 nano-particles are characterized using various physico-chemical characterization techniques like DTA/TGA, IR, XRD, vibrating sample magnetometer (VSM), TEM, and EDAX. The characterization results indicated that γ-Fe2O3 nano-particles (size 6–15 nm) are obtained by a thermal decomposition of an iron–hydroxy oleate precursor and possess spherical shape. These particles remained dispersed state in organic solvent due to capping action of oleate molecules. The results are quite reproducible and γ-Fe2O3 nano-particles can also be dispersed in another organic solvents like kerosene, 2-methyl naphthalene etc.

The degradation of Orange G, a monoazo dye, in aqueous solutions was investigated using as-synthesized and stored Fe-Ni bimetallic nanoparticles. Batch experiments with a nanocatalyst loading of 3 g/L showed complete dye degradation (150 mg/L) after 10 min of reaction time. HPLC-MS analysis of the degradation products showed that as-synthesized nanoparticles reductively cleaved the azo linkage to produce aniline as the major degradation product. However, 1-year-stored nanoparticles showed an oxidative degradation of Orange G through a hydroxyl-radical induced coupling of parent and/or product molecules. XPS analysis in corroboration with HPLC-MS data showed that the surface chemistry between Fe and Ni in as-synthesized and stored nanoparticles play a crucial role in directing the mode of degradation. Reductive dye degradation using as-synthesized nanoparticles proceeded through hydride transfer from nickel, whereas formation of a Fe2+ -Ni(0) galvanic cell in stored nanoparticles generated hydroxyl radicals from water in a nonFenton type reaction. The latter were responsible for the generation of radical centers on the dye molecule, which led to a coupling-mediated oxidative degradation of Orange G. The generation of hydroxyl radicals is further substantiated with radical quenching experiments using ascorbic acid indicating that stored nanoparticles degrade Orange G through a predominantly oxidative mechanism. HPLC-MS and XPS analysis of dye degradation using as-synthesized nanoparticles exposed to air and water confirmed that the reductive or oxidative degradation capability of Fe-Ni nanoparticles is decided by the time and type of catalyst aging process.

An interesting series of iron (III) complexes with naphthoquinone-thiosemicarbazones are synthesized and physico-chemically characterized by elemental analysis, UV-vis, IR, EPR and magnetic susceptibility measurements. They possess a cationic octahedral [FeL2]+ species and a tetrahedral [FeCl4]- anion and exhibit unusual spin-mixed states involving high-spin and low-spin ferric centers as revealed from magnetic behavior with significant amount of exchange interactions mediated by intermolecular associations. The magnetic susceptibility data is fitted with S1=5/2 and S2=1/2 Heisengberg's exchange coupled model; H=-2JS1S2 and the magnetic exchange interactions are found to be of the order of -13.6 cm-1 indicating the moderate coupling between two paramagnetic centers present in different chemical and structural environment. The presence of spin-paired iron (III) cation having dxz2dxz2dxz1 ground state is revealed from the EPR spectra with three prominent peaks while the high-spin tetrahedral iron (III) anion exhibits characteristics g=4 signal whose intensity increases with lowering the temperature suggesting its influence on the magnetic properties of the complex molecule. FTIR measurements indicate tridentate ONS donor systems involving quinone/hydroxyl oxygen, imine/hydrazinic nitrogen and thione/thiol sulfur atoms as binding sites for naphthoquinone-thiosemicarbazones.

An heteropoly acid (phosphotungstic acid, PTA) was found to be a promising solid acid catalyst as an alternative to the conventional stoichiometric reagents for the rearrangement of benzyl phenyl ether giving 2-benzyl phenol as a major product and 4-benzyl phenol and dibenzylated phenols as side products. Catalyst was recovered from the reaction mixture and reused again without loss of activity. Based on the observed product distribution for various substrates a plausible catalytic reaction pathway has also been proposed.

LC-UV scan of lisinopril revealed the presence of an unknown impurity (approximately 0.14%) at a relative retention time of 3.26 employing phosphate buffer-acetonitrile as binary gradient system while LC-MS analysis with binary gradient system comprising of a ammonia-ammonium acetate buffer (pH 5.0) and acetonitrile indicated it to be C31H41N3O7. The impurity was isolated by preparative HPLC utilizing a linear gradient of water and acetonitrile. The structural analysis of the isolated product by 1H, 13C NMR, mass spectroscopy and FT-IR revealed it to be a 4-phenyl butanoic acid derivative (CL) of lisinopril.

The presence of unknown impurity of the order of 0.2% was identified in benazepril using liquid chromatographic technique employing binary gradient system comprising acetic acid and ammonia in water and acetonitrile as the mobile phase. LCMS data corresponds to hydroxylated benazepril (OHB) derivative possessing the molecular formula C(24)H(28)N(2)O(6). This impurity was isolated using isocratic system containing ammonium acetate and acetonitrile and the product was characterized using FT-IR, (1)H and (13)C NMR and mass spectroscopy to ascertain the structure of the impurity. The spectroscopic analysis revealed the presence of hydroxyl function on C(17) carbon atom of benazepril molecule. The plausible mechanism for the formation of OHB species is proposed.

The performance of Co catalysts supported on MgO at different Co loading (10%–75%) for the formation of carbon nanotubes through acetylene decomposition at 600 ∘ C with H 2 /C 2 H 2 mixture for 1 h is investigated. The yield of MWNTs increases with an increase in Co loading (up to 50%). Starting from 1 g of catalyst precursor, about 8 g of MWNTs was obtained. The XRD patterns of catalyst precursor indicate the presence of cobalt in oxidic phase that eventually transformed into the catalytically active Co nanoparticles (12–18 nm) under the influence of acetylene and was responsible for the growth of coiled-like multi-walled CNTs as revealed by SEM and HRTEM images. It is suggested that bending in coil shaped MWNTs has the potential for functionalization for its biomedical applications.

Reactions of 2-thiosemicarbazido-1,4-naphthoquinone (NQTSC) with iron (II), iron (III), cobalt (II) and copper (II) chloride yield different complexes depending on the synthetic conditions. Under acidic medium, thionato coordination is favored with the formation of cationic complexes (A-1 to A-4) while neutral (B-1, B-3 and B-4) and cationic (B-2) complexes are isolated with thiolato binding under basic conditions. IR spectral data indicates that NQTSC acts as both a neutral and a mono-anionic tridentate ligand, bonding through thione, thiol or both as observed in the case of iron (III) and cobalt (III) complexes. The magnetic and Mossbauer measurements of iron (II) complexes reveal the presence of an unusual (S = 1) spin state possessing small zero-field splitting (ZFS). Reaction of NQTSC with iron (III) chloride results in the stabilization of the spin-triplet state (S = 3/2) with negligible contribution from ZFS components while cobalt complexes exhibit different magnetic properties displaying diamagnetic (A-3) cobalt (III) and low-spin cobalt (II) states (B-3). Evaluation of ESR covalency parameters for A-4 and B-4 indicates considerable delocalization of the unpaired electron present in the d x 2 - y 2 ground state of the tetragonally distorted octahedral geometry over the entire chelate rings formed by the NQTSC ligands. Electrochemical behavior of the complexes exhibit mostly metal-centered redox changes with the iron (III) complexes having a reversible Fe(III)/Fe(II) couple at relatively positive potentials while the copper (II) compounds display quasi-reversible Cu(II)/Cu(I) as well as Cu(III)/Cu(II) redox processes. Thiolato binding probably exerts a pronounced effect on the oxidation processes while thionato coordination seems to influence reduction steps in these complexes.

EPR, optical and redox studies have been carried out on six copper(II) complexes of naphthoquinone–thiosemicarbazones having [CuLCl] stoichiometry to elucidate the electronic structure, nature of metal–ligand bonding and electrochemical features. EPR spectra, simulated with an axial spin-Hamiltonian, exhibit a four-line pattern with nitrogen super-hyperfine couplings originating from imine/hydrazinic nitrogen atoms. These planar complexes possess a significant amount of tetrahedral distortion leading to a pseudo-square-planar geometry as evidenced from EPR and optical properties. The evaluation of covalency parameters suggest that the unpaired electron, present in the d x 2 - y 2 orbital, spends about 42–45% of its time on the nitrogen donor site of the coordinated thiosemicarbazones, reflecting the π-acceptor property of the sulfur center as well as the charge accumulating character of the quinone molecules. The presence of a strong π-interaction leads to extensive delocalization thorough the entire chelate rings formed by the tridentate ligands. Moderate covalency is observed in σ-bonding while in plane π-bonding possess appreciable covalent character. IR spectral data indicate a tridentate ONS donor set for these ligands. A quasi-reversible Cu(II)/Cu(I) redox couple is observed at relatively higher potential (ΔEp = −0.45 to −0.66 V) as a consequence of structural reorganizations, while these complexes exhibit lower redox potentials for the Cu(II)/Cu(III) oxidation process. There exists a linear relationship between the degree of tetrahedral distortion f(α) with spectroscopic and redox parameters.

Nanocrystalline indium particles are prepared by direct reaction of sodium metal with anhydrous indium trichloride in N,NVdimethylformamide (In-1 )o rn-trioctylphosphine (In-2 and In-3) as a solvent at a temperature between 120 and 360 8C under the atmosphere of argon. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Visible spectroscopy and thermogravimetric analysis (TGA). XRD patterns of In-1 exhibit broad peaks with particle diameter of about 15 nm while In-2 and In-3 particles have bigger particle size of about 50 nm reflecting the effect of solvents and reaction temperatures. Absorption spectroscopy measurements reveal the solvent dependence of surface plasmon resonance with the sharp absorption peaks at about 290 nm for In-1 in toluene and 260 nm for In-3 in dichloromethane. D 2004 Elsevier B.V. All rights reserved.

Binuclear octa-coordinated lanthanide(III) complexes of 2,3-dihydroxy-1,4-naphthoquinone (isnphth) possessing [M2L3(H2O)4] composition are synthesized and characterized by infrared spectroscopy, 1H and 13C NMR spectroscopy and thermal studies. The thermal decomposition revealed two stage patterns, 1st step corresponding to loss of four coordinated water molecules while the bonded isnphth molecules are decomposed during 2nd step. During the 2nd stage, the structure of these complexes is reorganized forming two distinct monomeric species implying that the ligand bridges as well as intermolecular associations are essential for thermal stability. Energy of activation (Ea) for 2nd stage exhibits linear increase with decrease in the size of lanthanide ion. 1H and 13C NMR spectrum of isnphth and its lanthanide chelate signifies strong hydroxyl oxygen and quinone binding. IR absorption spectral data indicate bonding through both hydroxyl oxygen with quinone carbonyls acting as bridge between lanthanide ions and there exists intensive network of intermolecular hydrogen bonding involving coordinated water and quinone carbonyls. The absorption spectrum of Nd(III) complex suggests a weak covalent character in metal–ligand bonding as revealed from nephelauxetic ratio (β = 0.973), covalent factor (b1/2 = 0.0641) and Sinha's factor (δ = 1.705).

Ho(III), Er(III) and Yb(III) complexes of 2-hydroxy-1,4-naphthoquinone-1-oxime derivatives having [ML3(H2O)2] are characterized using spectral and thermal decomposition studies. The thermolytic patterns suggested that they are decomposed in three distinct stages; 1ststage is related to the loss of two coordinated water molecules while one of the coordinated ligands and remaining two ligands are lost during subsequent 2nd and 3rd stages of degradation. After the 2nd stage, the structure of these complexes is reorganized reflecting that the structural associations through intermolecular hydrogen bonding network is essential for thermal stability. The kinetic parameters computed for 2nd step using the non-isothermal procedures of Coats-Redfern are applied to the respective differential thermogravimetric plots to ascertain the thermal degradation mechanism in air. The order of thermal decomposition reaction is found to be between 1-2 indicating that more than one intermediate might have simultaneously been formed. It also reveals the intermixing of 1st and 3rd stages of decomposition with the predominant 2nd stage leading to more gradual degradation. Energy of activation for 2nd stage of decomposition for these complexes is comparatively lower than those observed earlier for similar types of complexes. Other spectral data indicate oximino nitrogen and phenolato oxygen as coordination sites of 2-hydroxy-1,4-naphthoquinone monoximates.

Fe-Ni nanoparticles are used as catalyst for the selective hydrogenation of nitroarenes (I) to anilines (II) as well as cinnamic ester (III) to 3-phenylpropanoate (IV).

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼ 20 nm. TGA data revealed the drug payload of ∼ 18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6 °C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.