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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.

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.

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.

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 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.

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.

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.

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.

To ascertain the contribution of adsorptive capacity of Montmorillonite (MMT) towards photocatalytic process, CdSe-MMT nanocomposites are explored for adsorptive removal of Indigo Carmine (IC). The nanocomposites are prepared via two approaches: (a) in-situ formation and (b) wet impregnation of CdSe onto MMT support. XRD analysis of composites suggested the proper dispersion of CdSe nanoparticles in MMT clay matrix with spherical morphology of 5–10 nm sized CdSe nanoparticles. These nanocomposites are employed for photocatalytic degradation of IC under visible light at various IC concentrations and different amount of catalyst. Kinetics of IC is found to be of pseudo-second order with 10% in-situ and 50% loaded nanocomposites exhibiting better photocatalytic activity at 1.0 g L−1 catalyst and 100 mg L−1of IC. Dynamics of its adsorptive removal on the composite surface evaluated by employing error estimation tools clearly suggest that Redlich–Peterson and Flory–Huggins adsorption isotherms effectively describe the multi-layer process. It is observed that spontaneous, exothermic chemisorption process occurring on the surface indeed enhances photocatalytic activity. Moreover, such a feature is also found to be associated with diffusion of IC within mesoporous structure of MMT that subsequently favors pore-diffusion controlled adsorption process. IR spectral analysis demonstrated that IC molecule is degraded on the catalyst surface. Light or oxygenated species induced photocorrosion of CdSe is suppressed due to its composite formation with MMT that results in 620 ppm removal of IC during successive cycles; a feature ascribed as improved photocatalytic activity for CdSe nanoparticles.

Octa-coordinated La( III), Ce( III), Pr( III), Nd( III), Sm( III), Gd( III) and Dy( III) complexes of 3-amino-2-hydroxy- 1,4_naphthoquinone (3A2HNQ) of general formula [ M( 3A2HNQ),( H20)J have been synthesized and characterized. The non-isothermal thermogravimetric profiles indicate the loss of one of the coordinated ligands along with one coordinated water molecule at a significantly higher energy of activation than that of the second step of decomposition with loss of two ligands and one water molecule. Such a difference in the energy of activation for the two steps can be correlated to the strong intermolecular hydrogen bonding interactions between quinone carbonyls and coordinated water molecules. These chelates exhibit slightly lowered magnetic moments probably due to their polymeric nature. IR and far-IR spectral data suggest that phenolic oxygen and amino nitrogen are the coordinating sites for 3A2HNQ, while coordinated water molecules are involved in the intermolecular hydrogen bonding interactions with free quinone carbonyls of 3A2HNQ molecules. The nephelauxetic ratio (fl), covalency factor (h ‘jr) and Sinha’s parameter (ci) evaluated from electronic spectral studies of Ce( III), Sm( III), Gd( III) and Dy( III) reveal a negligible amount of covalency in metallligand bonding.

Chromium (III) and cobalt (III) complexes derived from 2-ketobutyric acid thiosemicarbazone (H,Kbtsc) have been prepared and characterized. Crystal structure analyses have shown both products to be mixed ligand complexes of the type M(HKbtsc) (Kbtsc) in which the thiosemicarbazone ligand is present in singly deprotonated "thione" and doubly deprotonated "thiol" forms. In each complex, the metal ion is bound to two tridentate ligands in a distorted octahedral geometry with meridional stereochemistry. Small but consistent structural differences between the two types of ligands are observed. Spectroscopic and electrochemical data are consistent with the formulations of these com- pounds as derived from the crystallographic results. Transition metal complexes of thiosemicarbazones, R,R,C=N-N(H)-C(S)NH, have been exten- sively studied and have been the subject of several recent reviews.lm3 Thiosemicarbazones have been shown to exhibit a range of types of biological activity which in a number of cases is thought to be related to their ability to chelate trace metals. Also, transition metal complexes of thiosemicarbazones have been found in some instances to have enhanced or modified activity in comparison to the uncom- plexed ligands.3 Simple thiosemicarbazones (R, = H ; RZ = alkyl or aryl) normally bind to transition metals as neutral bidentate ligands, with a five- membered chelate ring formed by metal-sulphur and metal-imine nitrogen bonds. A few cases of monodentate S-binding are known, as are instances of coordination as an anion, formed by depro- tonation at the imide nitrogen atom. Tridentate thiosemicarbazone derivatives may be obtained by

The crystal structure is reported of ammonium bis(pyruvic acid thiosemicarbazone)cobalt(III)·benzene, CoS 2 O 4 N 6 C 16 H 16 , which forms dark red triclinic crystals with unit cell parameters: a =9.307(2), b =9.555(2), c =14.729(3) A, α=67.04(1), β=118.89(2), γ=79.09(1)°, V =932.9(2) A 3 , space group P 1 . The final R factor for 3948 observed reflections is 3.1%. The distorted octahedral complex is held together by a hydrogen bonding system involving the ammonium and amine protons and the carboxylate oxygen and imine nitrogen atoms. The coordination polyhedron around the cobalt atom in the complex anion [Co(PVATSCH) 2 ] − is highly distorted from regular octahedral geometry as evidenced by the fact that the bond angles about the cobalt atom range from 83.40(6) to 96.75(5)°. The isolated meridional isomer contains a cis placement of the sulfur donor atoms with puckered ligand moieties arising from the non-planar hydrazinic chain with a folding angle of ca . 4° across the sulfur-nitrogen and oxygen-nitrogen atoms. The ligand H 2 PVATSC provides a strong ligand field and thus results in a low spin cobalt(III) complex. The complex undergoes a reversible one-electron reduction at the metal center.

A. Introduction (i) Biological importance of copper(H) complexes (ii) Historical interest in copper thiosemicarbazone complexes (iii) Synthesis (iv) Bonding types B. Crystal structures of copper thiosemicarbazones C. Magnetic studies (i) Magnetic moments (ii) Electron spin resonance spectra (a) Bis(thiosemicarbazones), Cu(SNNS) (b) Tridentate thiosemicarbazones, Cu(ONS) (c) Tridentate thiosemicarbazones, Cu(NNS) (d) Pentadentate thiosemicarbazones, Cu(SNNNS) D.Spectralstudies.. (i) Infrared spectra (ii) Electronic spectra E. Thermal studies F. Electrochemical studies G. Recent biological studies of thiosemicarbazones H. Conclusion References 50 50 51 52 52 53 56 56 57 57 58 59 60 60 60 61 63 64 65 66 67

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.

G. ALZUET, S. F E R R E R , J. BORR/i,S A N D X. SOLANS A comparison of the crystal structure of Acm reported by Mathew & Palenik (1974) with that of MAcm, shows the following remarkable facts: (1) The N(3)--N(4) distance [1.374(3)A in MAcm, 1.372 (3) A in Acm] does not change despite the presence of a methyl group bonded to N(4) in MAcm. (2) The S(6)--N(8) bond len~gth is significantly shorter in MAcm [1-575(2) A] than in Acm [1 594 (3)/k]. (3) The C(2)--N(3)--N(4), N(3)--N(4)--C(5) and C(5)--N(11)--C(12) angles are modified in MAcm compared to Acm probably due to differences in the C(5)--N(4) and C(5)--N(11) bonds. (4) The hydrogen-bond system is clearly different in both structures, as could be expected since, on the one hand, there is one less H atom available and on the other, the methyl substituent on N(4) prevents the formation of hydrogen bonds by the N(3) and N(4) ring atoms. Thus, only one significant hydrogen bond is observed from MAcm in contrast to the three (involving the N-thiadiazole atoms as well) exhibited by Acm. We greatly appreciate C I C Y T ( F A R 88-502). financial support from References ALLEN, F. H., KENNARD, O., WATSON, D. G., BRAMMER, L., ORPEN, A. G. & TAYLOR, R. (1987). J. Chem. Soc. Perkin Trans 2, pp. SI-Sl9. ALZUET, G., FERRER, S. & BORR~,S, J. (1991). J. Inorg. Biochem. CHATTERJEE, C., DATTAGUPTA, J. K. & SAHA, N. N. (1981). Acta Cryst. B37, 1835-1838. CRUICKSHANK, D. W. J. (1961). J. Chem. Soc. pp. 5486-5504. JOHNSON, C. K. (1965). ORTEP. Report ORNL-3794. Oak Ridge National Laboratory, Tennessee, USA. MATHEW, M. & PALENIK, G. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 532-536. SHELDRICK, G. M. (1976). SHELX76. Program for crystal struc- ture determination. Univ. of Cambridge, England. SHELDRICK, G. M. (1990). Acta Cryst. A46, 467-473. YOUNG, R. W., WOOD, K. H., EICHLER, J. A., VAUGHAN, J. R. & ANDERSON, G. W. (1956). J. Am. Chem. Soc. 78, 4649-4654. Acta Cryst. (1991). C47, 2379-2381 Hydrogen-Bonding Interactions in Thiosemicarbazones of Carboxylic Acids: Structure of 2-Ketobutyric Acid Thiosemicarbazone Hemihydrate BY PRAMILA SONAWANE, RAJEEV CHIKATE, AVINASH KUMBHAR AND SUBHASH PADHYE Department of Chemistry, University of Poona, Pune 411 007, India AND ROBERT J. DOEDENS Department of Chemistry, University of California, Irvine, California 92717, USA (Received 3 December 1990; accepted 3 May 1991) Abstract. 2-Thiosemicarbazonobutanoic acid hemi- hydrate, CsH9N302S.0 5H20, Mr = 184.22, triclinic, P1, a = 8.163 (2), b = 8.868 (2), c = 12.438 (2) A, a = 72 99 (2), /3 = 79 47 (2), y = 84 06 (2) °, V= 845 3 (3) A 3, Z = 4, Dx = 1 447 Mg m -3, A(Mo Kce) = 0.71073 A, /.1. = 0.332 mm-1, F(000) = 392, T = 296 K, R = 0-038 for 3830 independent reflections with I > 3~r(/). Three hydrogen bonds link the two crystallographically independent molecules in a pair- wise fashion. The two molecules both have E con- figurations about each C - - N and N - - N bond, but differ by nearly 180 ° in the orientation of the - - C O O H group. Introduction. The structure of the title compound was determined in order to provide a point of com- parison with a series of complexes of trivalent transi- tion metal ions in which it is present as a ligand in its singly and doubly deprotonated forms. One such metal complex of a closely related ligand has already been reported (Timken, Wilson & Hendrickson, Experimental. The compound was prepared as described by Sah & Daniels (1950). Large rhombic- shaped plates were grown by slow evaporation of a saturated solution in boiling water. Data were col- lected on a Nicolet/Siemens R3m/V diffractometer from a fragment of dimensions 0 . 6 0 x 0 . 5 0 x 0.33 mm that had been cut from a larger crystal. Unit-cell parameters were obtained from the setting angles of 32 reflections with 30--- 20___ 40 ° . 0/20 scans. Data collected for 4 __ 20 ___ 60 ° with 0 _< h - < l l , - 1 2 - < k - - - 1 2 , - 1 6 - < l - - - 1 7 . No absorption © 1991 International Union of Crystallography

Coordinately unsaturated Cu(II) and Fe(III) complexes of the stoichiometry [Cu(L)Cl] and [Fe(L)Cl2], where L = tridentate anion of 2-hydroxy-1,4-naphthoquinone 1-thiosemicarbazone (2HNQTSC) and its 3-methyl derivative (3M2HNQTSC), were screened in vitro against P388 lymphocytic leukemia cells. Copper complexes were found to be more effective inhibitors of DNA synthesis than analogous Fe(III) compounds. The inhibitory activities are suggested to be related to Cu(II)-Cu(I) redox couple or nitrogen adduct formation.

Three complexes, [MnII2L1(CH3CO2)2(CH3OH)]2 (1), (MnII2L2(CH3CO2)2 (CH3OH))2 (2), and (MnII2HL3(CH3CO2)2(CH3OH))2 (3), wherein H2L1 = 3-[(((2‘-pyridyl)methyl)imino)methyl]benzene-1,2-diol, H2L2 = 3-[((2-(2‘-pyridyl)ethyl)imino)methyl]benzene-1,2-diol, and H3L3 = 3-[((2-(4‘-imidazolyl)ethyl)imino)methyl]benzene-1,2-diol, have been synthesized and studied. 1 crystallizes in the monoclinic system, space group P21/c, Z = 2, a = 11.396(1) A, b = 18.583(2) A, c = 9.888(1) A, and β = 103.51(1)°. The structure was solved by direct methods and refined to conventional agreement indices R = 0.028 and Rw = 0.029. The molecular structure of 1 consists of discrete [MnII2L1(CH3CO2)2(CH3OH)]2 molecules. 1 is a chainlike bis-dinuclear Mn(II) complex involving an unprecedented arrangement of pentacoordinated (N2O3) and hexacoordinated (O6) manganese ions as the outer and inner pairs of metal centers, respectively. The different Mn···Mn distances result from significant differences in bridging moieties, two catecholato brid...