Synthesis, Characterization, Investigation of DNA Interactions and Biological Evaluation of Co(II), Ni(II), Cu(II) and Zn(II) Complexes with Newly Synthesized 2-methoxy 5-trifluoromethyl benzenamine Schiff Base.

The biologically active and thermally stable bivalent Co(II), Ni(II), Cu(II), and Zn(II) complexes (C1, C2, C3, and C4) of novel Schiff base ligand [(5-trifluoromethyl-2-methoxyphenylamino)methyl)-4,6-diiodophenol (L)] have been synthesized. The structural analysis of these complexes have been carried out by elemental analysis, 1H-NMR, FTIR, ESI mass, UV-visible, ESR, TGA techniques and magnetic measurements. The obtained results were confirmed as square planar geometry for Ni(II) and Cu(II) complexes, whereas octahedral geometry for Co(II) and Zn(II) complexes. The geometry optimized structures were developed by employing CHEM 3D software. The DNA binding interaction studies such as UV-vis absorption, viscosity, and fluorescence studies have been confirmed that the mode of binding of complexes with DNA is an intercalative binding. The DNA cleavage studies revealed that all the complexes are found to be potent to cleave the DNA into Form I & II. The in-vitro pathological studies of all the complexes against various microbial strains (Gram + and Gram -), revealed that Cu(II) complexes are more potent compared to other complexes and Schiff base. The anti diabetic activity studies revealed that the Cu(II) complex exhibited slightly higher activity than Co(II), Ni(II), and Zn(II) complexes. The results of antioxidant activity by DPPH method, suggested that the Cu(II) complex has higher activity and comparable with the standard compounds.

Design, Synthesis, Structural Investigation and Photo Induced Biological Investigations of Co(II), Ni(II) and Cu(II) Complexes Derived from N,O Donor Schiff Bases.

A series of chelated metal complexes, [Co(LI)2] (1), [Ni(LI)2] (2), [Cu(LI)2] (3) [Co(LII)2] (4), [Ni(LII)2] (5) and [Cu(LII)2] (6) were designed and synthesized from newly synthesized Schiff bases, LI = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-5-methylphenol and LII = 2-((E)-(5-(4-fluorophenyl)isoxazol-3-ylimino)methyl)-4-chlorophenol. The synthesized compounds were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (NMR), electronic spectroscopy (UV-Vis), infrared spectroscopy (FT-IR), magnetic susceptibility (µeff), electron spin resonance spectroscopy (ESR), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and powder X-ray diffraction analysis (P-XRD). The spectral investigations have been clearly suggested 1:2 (metal: ligand) stoichiometric complexes with square planar geometrical arrangement around the metal ion. The thermal gravimmetric analysis (TGA) of these complexes indicates greater thermal stability and various steps involved in thermal decomposition of metal complexes. The binding ability between these metal complexes and calf thymus DNA (CT-DNA) was investigated by UV-Vis, fluorescence spectroscopy and viscometric experiments, which disclosed that, the complexes interacted to CT-DNA via an intercalation binding mode. The cleavage property of metal complexes against pBR322 DNA has been explored by gel electrophoresis technique mediated by UV-illumination and H2O2, showed momentous cleavage activity. Antioxidant activity of all complexes was determined by DPPH free radical scavenging experiment and showed prominent antioxidant activity. Further, the antibacterial and antifungal activities of all compounds were screened against bacterial and fungal strains via in-vitro disc diffusion method. These studies revealed that the complexes showed comparatively more antimicrobial activity than free ligands against tested microbial strains.

Hydrothermal Fabrication of Efficient Binary Pd/Ag2S Heterojunction Composites: Synthesis, Characterization, and Fluorometric Selective Sensing of Organophosphate Pesticides.

Although many plasmonic nanosensors have been established for the detection of analytes, few of them are feasible for analyzing natural samples with very complex matrices because of insufficient method selectivity. To address this challenge, we propose an epitaxial and lattice-mismatch approach to the synthesis of a unique Pd/Ag2S nanostructure, which consists of a Pd segment with excellent plasmonic characteristics, and a highly stable Ag2S portion with minimum solubility product (Ksp(Ag2S) = 6.3 × 10- 50). Hence, Ag2S nanoparticles (NPs) and optimized (10.05 mmol/L) Pd/Ag2S composite were prepared using a hydrothermal method. The fabricated samples were characterized using different tools including UV-vis DRS, PL, powder XRD, TEM, and BET surface area measurements. Furthermore, the fluorometric sensing performance of the Ag2S and Pd/Ag2S samples was examined in the detection of organophosphate pesticides such as MLT, PRT, DZN, FNT, DCL, MCP, and CPS pesticides at room temperature. The quantitative detection of MLT, PRT, DZN, FNT, DCL, MCP, and CPS pesticides was achieved based on the Pd/Ag2S composite and organophosphate group-specific interaction. The optimized sensor exhibited a lower limit of detection (3.08 µM), excellent reproducibility, selectivity, and stability with an enhanced sensitivity of - 207.1 µA/µM cm2 (R2 = 0.98) in the range of 10 µM-100 µM for the detection of CPS pesticide. In addition, the fluorometric sensor has excellent selectivity, reproducibility, and stability, providing a feasible method for not only the detection of CPS pesticides but also other analytes in the future.

Fabrication of CuNPs Using Schiff Base Ligand and Their Catalytic Reduction of Pharmaceutical Drugs, Fluorescence Selective Detection of Cd2+, Antimicrobial, and Antioxidant Activities.

Here, we have approached the synthesis of copper nanoparticles (CuNPs) Schiff base (5-trifluoromethoxy-2-(((2chloro-5-(methyl)phenyl)imino)methyl)phenol)). The synthesized CuNPs were characterized by UV-vis spectroscopy, PL, FTIR, powder XRD, and TEM analysis. From the UV-vis absorption spectroscopy, an absorption peak was observed at 585 nm. As a result of the powder XRD and TEM studies, spherical particle sizes ranged between 4 and 10 nm. FT-IR analysis confirmed the presence of functional groups ‒OH, C=C, -C=N-, and C‒H triggers the synthesis of CuNPs. Further, the catalytic property of the CuNPs were revealed by the degradation of pharmaceutical drugs such as Capecitabine (CAP) and Ciprofloxacin (CIP) in 90 min of reaction time in the presence of NaBH4. The reaction kinetics followed pseudo-first-order with k-values (rate constant) 0.248 min-1 and 0.307 min-1. In addition, the synthesized CuNPs have exhibited selective sensing detection of Cd2+ metal ions in different range of concentration (10-100 µM) by spectrofluorometrically with the limit of detection (LOD) is 0.0284 nM and limit of quantification (LOQ) is 0.0586 nM. The CuNPs revealed significant antioxidant activities against DPPH as a common free radical at 50 µg/mL with 71.24% of scavenging activity. The maximum antimicrobial potential and zone of inhibition of P. Aeruginosa is 17.25±0.8 mm and A. niger is 12.1 mm by using CuNPs.

Biogenic Synthesis of Carboxymethyl Cashew Gum Modified Gold Nanoparticles and its Sensitive and Selective Calorimetric Detection of Hg2+ Ions and Catalytic Reduction of Methyl Red.

In the present study, we have successfully synthesized and characterized carboxy methyl cashew gum modified gold nanoparticles (CMCG-AuNPs) via a microwave-assisted method and used as a calorimetric probe for selective detection of Hg2+ ions as well as catalytic reduction of methyl red in an aqueous medium. The effect of different parameters including concentration and irradiation time on the formation of CMCG-AuNPs was also investigated. The presence of strong surface plasmon resonance (SPR) peak in the visible region indicated the formation of AuNPs. The characterization techniques were identified the interaction between the CMCG and AuNPs with estimation of size and morphology. The face centred cubic (FCC) crystal structure was identified by using XRD and supporting with SAED pattern. TEM images of CMCG-AuNPs were exhibited as polydispersed with spherical in shape and the average particle size was 12 ± 3 nm. The synthesized CMCG-AuNPs were utilized to sensing Hg2+ ions in an aqueous medium, the presence of Hg2+ ions selectively among other metal ions, the CMCG-AuNPs were aggregated by changing the color from wine red to purple blue accompanied by change in the position of SPR peak and intensity. It was observed as a strong linear relationship based on the change in intensity, the limit of detection was determined to be 0.277 nM. The catalytic activity was also examined for the reduction of methyl red (MR) in the presence of CMCG-AuNPs was completed within 12 min and followed pseudo-first order kinetics with a rate constant of 0.261 min-1. From the obtained results, the synthesized CMCG-AuNPs were useful for detection of heavy metal ions as well as toxic pollutants degradation via a green method, and utilized sensing, environmental, and biomedical application in future.

Microwave-assisted fabrication of g-C3N4 nanosheets sustained Bi2S3 heterojunction composites for the catalytic reduction of 4-nitrophenol.

In this work, we report a stable g-C3N4, Bi2S3, and g-C3N4/Bi2S3 composite catalysts were prepared via a facile one-pot microwave-assisted method and characterized. The orthorhombic phase and nearly spherical shape of the particles with an average diameter of 5-25 nm of g-C3N4/Bi2S3 composite were obtained from XRD and TEM. The composite also exhibits a high surface area (32.15 m2/g), which may provide convenient transportation and diffusion for substrate molecule. The optical studies were displayed the g-C3N4/Bi2S3 composite has a sharp absorption band in the visible region, higher charge separation, and reduced recombination rate. These results show that the Bi2S3 NPs have good crystallinity and are uniformly deposited on the surface of the g-C3N4 sheet. The catalytic performance of the g-C3N4/Bi2S3 composite for the reduction of 4-NP to 4-AP was exhibited approximately 100%, which is 1.48 and 2.34 times higher than the Bi2S3 and g-C3N4 catalysts, respectively. The pseudo-first-order rate constant was estimated as 1.648 × 10 -2 min-1 for the reduction of 4-NP using g-C3N4/Bi2S3 composite in 1 h reaction time. The effect of catalyst dosage (0-30 mg) was also investigated for the reduction of 4-NP using g-C3N4/Bi2S3 composite catalyst. Moreover, the reusability of the g-C3N4/Bi2S3 composite was exhibited a better reduction of the 4-NP even after 5 cycles and it was found that 8% reduction in the initial reduction rate. The obtained results from this study show that g-C3N4/Bi2S3 composite has the potential efficiency and stability to make it an ideal catalyst for the reduction of toxic effluents and wastewater treatment.

Facile synthesis, characterization and enhanced catalytic reduction of 4-nitrophenol using NaBH4 by undoped and Sm3+, Gd3+, Hf3+ doped La2O3 nanoparticles.

This work focuses on the synthesis of undoped and doped lanthanum oxide nanoparticles (La2O3 NPs) by a simple co-precipitation method for the catalytic reduction of 4-nitrophenol (4-NP) using NaBH4 as a reducing agent. Their optical properties, morphologies, structure, chemical compositions and electronic properties were carefully characterized by XRD, FTIR, SEM, TEM, PL and UV-visible absorption spectroscopy. The SEM and TEM images showed various shape morphologies and sizes of the particles. The XRD pattern revealed a polycrystalline nature with the hexagonal structure of the La2O3 NPs. The synthesized undoped and doped La2O3 NPs were also employed as catalysts for the reduction of 4-nitrophenol, it shows that the doped (Sm3+, Gd3+ and Hf3+) La2O3 NPs provided better catalytic activity than the undoped La2O3 NPs. Moreover, Hf3+ doped La2O3 NPs exhibited an enhanced catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in 90 min. The catalytic conversion was studied by UV-vis spectroscopy with high reduction rate (k = 2.048 min-1). The applications of the present study may utilize in the removal of toxic pollutants in a cleaning of environmental pollution as well as in industrial applications.

Ternary semiconductor ZnxAg1-xS nanocomposites for efficient photocatalytic degradation of organophosphorus pesticides.

The construction of ternary semiconductor nanostructures has attracted much attention in photocatalysis by virtue of their tunable elemental composition and band structure. Here, ternary semiconductor ZnxAg1-xS (0 ≤ x ≤ 1) composites were successfully prepared by a simple and low-cost hydrothermal method without using any surfactant. Combined analyses using XRD, N2 sorption, SEM, TEM and UV-vis DRS revealed that the ternary composite semiconductor materials exhibited well-developed crystalline frameworks, large surface areas of 15-70 m2 g-1, sizes of 10-30 nm, and outstanding UV light absorption properties. Data from XRD and TEM indicate that photocatalysis might contribute to the formation of the strong interfacial interaction between ZnS and Ag2S nanoparticles. The photocatalytic activities were investigated via the degradation of organophosphorus pesticides, including malathion (MLT), monocrotophos (MCP) and chlorpyrifos (CPS), using the ZnxAg1-xS composites under UV light irradiation. The toxicity of MLT, MCP, and CPS was reduced by photocatalysis and photolysis; however, photocatalysis had a greater impact. Superior photocatalytic performance was exhibited by the Zn0.5Ag0.5S catalyst owing to its large surface area and the presence of Ag0 with improved charge transfer in comparison with that of bare ZnS and Ag2S. Assays of stability and reusability indicated that the Zn0.5Ag0.5S composite retained more than 85% of its activity after five cycles of use. On the basis of the results, a possible photocatalytic mechanism of the prepared samples was proposed. This study indicates a potential application of the ternary semiconductor materials in the efficient UV light-driven photocatalytic degradation of other pollutants that may cause environmental pollution.

Green Synthesis, Optical, Structural, Photocatalytic, Fluorescence Quenching and Degradation Studies of ZnS Nanoparticles.

The study describes a simple hydrothermal method for the synthesis of zinc sulfide nanoparticles (ZnS NPs) using bovine serum albumin (BSA). The synthesized NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), fluorescence, UV-visible diffuse reflectance spectra (DRS) and zeta potential techniques. The morphologies and sizes were characterized by SEM and TEM. The size of ZnS NPs was observed with an effective diameter size of 20 nm. The photocatalytic activity of ZnS NPs was evaluated by the degradation of rhodamine B (RB) dye under sunlight irradiation. The degradation reaction follows the pseudo-first order kinetics. In addition, the fluorescence quenching and binding of ZnS NPs with crystal violet (CV) molecules have been studied. The binding constant (Ka) between ZnS NPs and CV is calculated using modified Stern-Volmer equation. The photocatalytic degradation and kinetics of CV dye by ZnS NPs in the presence of UV light has been investigated using spectrofluorometer.

Green synthesis, characterization, photocatalytic, fluorescence and antimicrobial activities of Cochlospermum gossypium capped Ag2S nanoparticles.

The study describes a simple and green method for the synthesis of silver sulfide nanoparticles (Ag2S NPs) using gum kondagogu (Cochlospermum gossypium) (GK). The synthesized NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), fluorescence, UV-vis absorption, zeta potential and thermogravimetric analysis (TGA) techniques. The optical properties and quantum confinement effect of the products were confirmed by means of spectroscopic measurements. The morphologies and sizes were characterized by SEM and TEM. The Ag2S NPs were spherical in shape with an effective diameter size of 25 nm. The photocatalytic property of Ag2S NPs was evaluated by the degradation of fluorescein (FL) dye under solar light. The effect of Ag2SNPs on the photocatalytic degradation of FL dye and influence of other parameters such as Ag2S loading, H2O2, temperature and under solar light irradiation was also evaluated. The degradation reaction follows the pseudo-first order kinetics. The apparent reaction rate was used to calculate the apparent activation energy (Ea=13.95 kJ/mol) of the degradation process. The activation thermodynamic parameters (ΔG*, ΔH* and ΔS*) were obtained from variable temperature kinetic studies. The interaction between Ag2S NPs and bovine serum albumin (BSA) was studied by using fluorescence spectroscopic measurements. The synthesized Ag2S NPs were showing good antimicrobial activity.

Synthesis, Characterization, Fluorescence, Photocatalytic and Antibacterial Activity of CdS Nanoparticles Using Schiff Base.

Cadmium sulfide nanoparticles (CdS NPs) were successfully prepared using sonochemical method by employing Schiff-base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a complexing agent. Here, SB is used as a ligand to control the morphology of NPs. XRD patterns and TEM images show that the synthesized CdS NPs have cubic structures with a diameter of about 2-10 nm. The formation of CdS NPs and their optical, structure, thermal and morphologies were studied by means of UV-vis DRS, fluorescence, FTIR, zeta potential, XRD, SEM and TEM. The interactions between CdS NPs and SB were investigated in an aqueous solution using fluorescence spectroscopy. The fluorescence quenching studies suggest that SB quenches the fluorescence of CdS NPs effectively. The degradation kinetics of methyl red (MR) by the photocatalyst was followed by Langmuir-Hinshelwood model. The results revealed that photocatalytic degradation of MR by SB capped CdS NPs could be considered as a practical and reliable technique for the removal of environmental pollutants. The antibacterial activity of samples was evaluated against E. coli, S. aureus and P. aeruginosa and the results were compared. SB and SB capped CdS NPs could be a potential antibacterial compounds after further investigation.