Oxadiazole Schiff Base as Fe3+ Ion Chemosensor: "Turn-off" Fluorescent, Biological and Computational Studies.

Compound, (E)-5-(4-((thiophen-2-ylmethylene)amino)phenyl)-1,3,4-oxadiazole-2-thiol (3) was synthesized via condensation reaction of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol with thiophene-2-carbaldehyde in ethanol. For the synthesis and structural confirmation the FT-IR, 1H, 13C-NMR, UV-visible spectroscopy, and mass spectrometry were carried out. The long-term stability of the probe (3) was validated by the experimental as well as theoretical studies. The sensing behaviour of the compound 3 was monitored with various metal ions (Ca2+, Cr3+, Fe3+, Co2+, Mg2+, Na+, Ni2+, K+) using UV- Vis. and fluorescence spectroscopy techniques by various methods (effect of pH and density functional theory) which showing the most potent sensing behaviour with iron. Job's plot analysis confirmed the binding stoichiometry ratio 1:1 of Fe3+ ion and compound 3. The limit of detection (LOD), the limit of quantification (LOQ), and association constant (Ka) were calculated as 0.113 µM, 0.375 µM, and 5.226 × 105 respectively. The sensing behavior was further confirmed through spectroscopic techniques (FT-IR and 1H-NMR) and DFT calculations. The intercalative mode of binding of oxadiazole derivative 3 with Ct-DNA was supported through UV-Vis spectroscopy, fluorescence spectroscopy, viscosity, cyclic voltammetry, and circular dichroism measurements. The binding constant, Gibb's free energy, and stern-volmer constant were find out as 1.24 × 105, -29.057 kJ/mol, and 1.82 × 105 respectively. The cleavage activity of pBR322 plasmid DNA was also observed at 3 × 10-5 M concentration of compound 3. The computational binding score through molecular docking study was obtained as -7.4 kcal/mol. Additionally, the antifungal activity for compound 3 was also screened using broth dilution and disc diffusion method against C. albicans strain. The synthesized compound 3 showed good potential scavenging antioxidant activity against DPPH and H2O2 free radicals.

Biomediated synthesis, characterization, and biological applications of nickel oxide nanoparticles derived from Toona ciliata, Ficus carica and Pinus roxburghii.

Biomediated ecofriendly method for the synthesis of nickel oxide nanoparticles using plants extracts (Toona ciliata, Ficus carica and Pinus roxburghii) has been reported. The nanoparticles so obtained were characterized by various techniques such as ultraviolet-visible, powder X-ray diffraction, Fourier transform infrared spectroscopy, attenuated total reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis and fluorescence spectroscopy. Formation of nickel oxide nanoparticles was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction where the former technique ascertains the formation of bond between nickel and oxygen. The nickel oxide nanoparticles were found to be crystalline cubic face centered and show intense photoluminescence emission at 416, 414 and 413 nm, respectively. The antibacterial activity was studied against gram positive and gram negative bacterial species by agar well diffusion method. The nickel oxide nanoparticles show better activity against some bacterial strains with reference to the standard drugs Ciprofloxacin and Gentamicin. The anthelmintic activity against Pheretima posthuma of nanomaterials obtained from Pinus roxburghii was found to be greater than that derived from Toona ciliata and Ficus carica using the standard drug Albendazole. This method takes the advantage of the sustainable and economic approach for the synthesis of metal oxide nanoparticles.

Physicochemical and Pharmacokinetic Analysis of Anacardic Acid Derivatives.

Anacardic acid (AA) and its derivatives are well-known for their therapeutic applications ranging from antitumor, antibacterial, antioxidant, anticancer, and so forth. However, their poor pharmacokinetic and safety properties create significant hurdles in the formulation of the final drug molecule. As a part of our endeavor to enhance the potential and exploration of the anticancer activities, a detailed study on the properties of selected AA derivatives was performed in this work. A comprehensive analysis of the drug-like properties of 100 naturally occurring AA derivatives was performed, and the results were compared with certain marketed anticancer drugs. The work focused on the understanding of the interplay among eight physicochemical properties. The relationships between the physicochemical properties, absorption, distribution, metabolism, and excretion attributes, and the in silico toxicity profile for the set of AA derivatives were established. The ligand efficacy of the finally scrutinized 17 AA derivatives on the basis of pharmacokinetic properties and toxicity parameters was further subjected to dock against the potential anticancer target cyclin-dependent kinase 2 (PDB ID: 1W98). In the docked complex, the ligand molecules (AA derivatives) selectively bind with the target residues, and a high binding affinity of the ligand molecules was ensured by the full fitness score using the SwissDock Web server. The BOILED-Egg model shows that out of 17 scrutinized molecules, 3 molecules exhibit gastrointestinal absorption capability and 14 molecules exhibit permeability through the blood-brain barrier penetration. The analysis can also provide some useful insights to chemists to modify the existing natural scaffolds in designing new anacardic anticancer drugs. The increased probability of success may lead to the identification of drug-like candidates with favorable safety profiles after further clinical evaluation.

Application of FTIR-ATR spectroscopy to confirm the microwave assisted synthesis and curing of Cashew nut shell liquid derived nanostructured materials.

The present work reports the development of nanostructured material from Cashew nut shell liquid (CNSL, an agro byproduct of cashew industry, 87% cardanol) to evaluate their potential in antibacterial applications as a substitute of petroleum feedstock via an energy-efficient method. The nanostructured material was synthesized by coordination polymerization reaction of cardanol and divalent Mn(II) salt with the aid of microwave irradiations. FTIR spectroscopy was used to confirm the proposed structure of the synthesized materials. FTIR-ATR spectroscopy was employed to verify the curing of material by comparing the spectra of the cured samples with the frequencies of uncured samples. Magnetic moment and UV-visible spectroscopy were used to confirm the proposed structure of the material further. Morphology of the synthesized material was investigated by XRD, optical microscopy, SEM and TEM and thermal behaviour by TGA/DTG/DSC technique. Agar diffusion method was utilized to investigate the antibacterial activity of the synthesized material against bacterial strains E. coli, K. pneumoniae, B. subtilis and S. aureus. N2 adsorption-desorption was investigated to check BET specific surface area and BJH pore size distribution of the same. The results revealed that the synthesized materials were obtained as semicrystalline, porous, thermally stable and nanostructured film forming materials with moderate to good antibacterial activity against different nosocomial bacteria. They can be used as thermally stable antibacterial agents in the field of films/coatings for health care applications.

Copper Oxide Nanomaterials Derived from Zanthoxylum armatum DC. and Berberis lycium Royle Plant Species: Characterization, Assessment of Free Radical Scavenging and Antibacterial Activity.

Copper oxide nanomaterials were synthesized by a facile sustainable biological method using two plant species (Zanthoxylum armatum DC. and Berberis lycium Royle). The formation of materials was confirmed by FT-IR, ATR, UV-visible, XRD, TEM, SEM, EDX, TGA and PL. The antibacterial activity was evaluated by agar well diffusion method to ascertain the efficacy of plant species extract and extract derived copper oxide nanomaterials against six Gram-positive bacteria namely Staphylococcus aureus, Streptococcus mutans, Streptococcus pyogenes, Corynebacterium diphtheriae, Corynebacterium xerosis, Bacillus cereus and four Gram-negative bacteria such as Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris against the standard drug, Ciprofloxacin for Gram-positive and Gentamicin for Gram-negative bacteria, respectively. In both cases, copper oxide nanomaterials were found to be sensitive in all the bacterial species. Sensitivity of copper oxide nanomaterials shows an be higher as compared to plant species extract against different bacteria. Scavenging activity of plant extracts along with nanomaterials have been accessed using previously reported protocols employing ascorbic acid as standard. Scavenging activity of copper oxide nanomaterials shows an increase with increase in concentration. The biological activity (bactericidal and scavenging efficiency) of plant derived copper oxide nanomaterials revealed that these materials can be used as potent antimicrobial agent and DPPH scavengers in industrial as well as pharmacological fields.

Development of coordination polyureas derived from amine terminated polyurea and metal ions having 'd5', 'd7', 'd8' and 'd10' orbitals: From synthesis to applications.

Amine terminated polyureas [ATPUa] were synthesized by 'in situ' condensation polymerization of toluene diisocyanate (TDI) with equimolar ratio of ethylene diamine (ED) and water. Incorporating the completely half-filled {Mn(II) d5}, partially filled {Co(II) d7, Ni(II) d8} and fulfilled {Zn(II) d10} divalent metal ions in APTUa generated the coordination polyureas (CPa). The structure and geometry of resulting CPa was ascertained by spectral techniques, the Fourier transform (FTIR), UV-Visible and nuclear magnetic resonance (1H NMR) spectroscopy. Amorphous/semi-crystalline and rough/layered surface morphology was analyzed by X-ray diffraction analysis (XRD) and field emission scanning electron microscopy along with energy dispersive X-ray spectroscopy (FESEM/EDX). Good thermal stability was observed having the trend, ATPUa-Zn(II) > ATPUa-Mn(II) > ATPUa-Co(II) > ATPUa-Ni(II) > ATPUa [with IPDT values, 712 °C of ATPUa-Zn(II), 673 °C of ATPUa-Mn(II), 582 °C of ATPUa-Co(II), 563 °C of ATPUa-Ni(II), 488 °C of ATPUa] respectively. It was analyzed by thermo-gravimetric, differential thermal, differential scanning calorimetry and integral procedure decomposition temperature analysis (TGA/DTA/DSC/IPDT). Good adsorption/desorption behavior of CPa was analyzed with the help of batch adsorption techniques, and it was found that CPa {in order; ATPUa-Ni(II) > ATPUa-Mn(II)}can be used as effective dye adsorbent (up to 97%) for the waste water treatment. The CPa were screened for their in-vitro antimicrobial activity against six gram positive and three gram negative bacterial strains as compared to standard drug (Ciprofloxacin and Gentamicin) and moderate antimicrobial activity was observed.

Malus pumila and Juglen regia plant species mediated zinc oxide nanoparticles: Synthesis, spectral characterization, antioxidant and antibacterial studies.

Zinc oxide nanoparticles derived from Malus pumila (apple) and Juglen regia (walnut) plant is an attractive area of research because of their widespread use. The use of plant material to synthesize zinc oxide nanoparticles has been considered as one of the best environmentally friendly approach. This method appears to be low-cost as compare to other conventional method of synthesis. The biosynthesized nanoparticles were characterized by Ultraviolet-visible spectroscopy (UV-visible), Fourier transform infrared spectroscopy (FT-IR), Attenuated total reflectance spectroscopy (ATR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron Microscopy (TEM) and Dynamic light scattering (DLS). The antioxidant potential has been evaluated by 2, 2-diphenyl-1-picrylhydrazyl free radical (DPPH) assay using L-ascorbic acid as a standard. The antibacterial activity was measured by agar well diffusion method to measure the efficacy of plant species extract and extract mediated zinc oxide nanoparticles against 5 g positive bacteria namely Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), Streptococcus pyrogenes (S. pyrogenes), Corynebacterium diphtheriae (C. diphtheriae) and Corynebacterium xerosis (C. xerosis) and 3 g negative bacteria such as Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae) and Pseudomonas aeruginosa (P. aeruginosa) bacteria with standard antibiotic for gram positive (Ciprofloxacin) and gram negative bacteria (Gentamicin).

Biogenic synthesis of iron oxide nanoparticles using Agrewia optiva and Prunus persica phyto species: Characterization, antibacterial and antioxidant activity.

A phytoextract mediated synthesis of iron oxide nanoparticles using Agrewia optiva (Dhaman or Biul) and Prunus persica (Peach) leaf extract as capping and stabilizing agent without using hazardous toxic chemicals via biogenic route has been studied. The biogenic method of synthesis is convenient, rapid, cost effective and ecofriendly. The green synthesized nanoparticles were characterized by Ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Attenuated total reflectance spectroscopy, X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and dynamic light scattering measurements. The antibacterial study was determined by agar well diffusion method to measure the efficiency of both phyto species extract and its mediated iron oxide nanoparticles against five gram positive bacterial stains such as Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), Streptococcus pyrogenes (S. pyrogenes), Corynebacterium diphtheriae (C. diphtheriae) and Corynebacterium xerosis (C. xerosis) and three gram negative bacterial stains such as Escherichia coli (E. coli), Klebsiella pneuomoniae (K. pneuomoniae) and Pseudomonas aeruginosa (P. aeruginosa). The antibiotic Ciprofloxacin and Gentamicin have been used as reference standard drugs for gram positive and gram negative bacterial stains, respectively. The antioxidant activity of the phyto extracts and prepared nanoparticles have been performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay employing l-ascorbic acid as a standard.

Synthesis, vibrational spectrometry and thermal characterizations of coordination polymers derived from divalent metal ions and hydroxyl terminated polyurethane as ligand.

A series of novel coordination polyurethanes [HTPU-M, where M=Mn(II) 'd5', Ni(II) 'd8', and Zn(II) 'd10'] have been synthesized to investigate the effect of divalent metal ions coordination on structure, thermal and adsorption properties of low molecular weight hydroxyl terminated polyurethane (HTPU). HTPU-M have been synthesized in situ where, OH group of HTPU (synthesized by the condensation polymerization reaction of ethylene glycol (EG) and toluene diisocyanate (TDI) in presence of catalyst) on condensation polymerization with metal acetate in presence of acid catalyst synthesized HTPU-M followed by coordination of metal ions with hetero atoms. The structure, composition and geometry of HTPU-M have been confirmed by vibrational spectrometry (FTIR), 1H NMR, elemental analysis and UV-Visible spectroscopy. Morphological structures of HTPU-M were analyzed by X-Ray Diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray spectroscopy (EDX) and High Resolution Transmission Electron Microscope (HR-TEM) techniques. The thermal degradation pattern and thermal stability of HTPU-M in comparison to HTPU was investigated by thermal-gravimetric (TG)/differential thermal (DT), analyses along with Integral procedure decomposition temperature (IPDT) by Doyle method. The molecular weight of HTPU was determined by gel permeation chromatography (GPC). The preliminary adsorption/desorption studies of HTPU-M for Congo red (CR) was studied by batch adsorption techniques. The results indicated that HTPU-M have amorphous, layered morphology with higher number of nano-sized grooves in comparison to HTPU. Coordination of metal to HTPU plays a key role in enhancing the thermal stability [HTPU-Ni(II)>HTPU-Mn(II)>HTPU-Zn(II)>HTPU]. The HTPU-M can be utilized for industrial waste water treatment by removing environmental pollutants.

Synthesis, characterization and antimicrobial study of polymeric transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II).

Salen ligands comprising of o-phenylenediamine (salop) and p-phenylenediamine (salpp) have been synthesized. The salen ligand, salop undergo Schiff base reaction with Formaldehyde and Barbituric acid to generate novel polymeric Schiff base, SBOPA in one instance while the second salen ligand, salpp on Schiff base reaction with formaldehyde and piperazine gives another novel polymeric Schiff base, SBPBA. These polymeric Schiff base ligands, SBOPA and SBPBA generates polymeric metal complexes in high yields on reaction with transition metal acetates, M(CH3COO)2.xH2O where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The polymeric Schiff bases, SBOPA and SBPBA and their transition metal complexes were systematically characterized, using various spectroscopic techniques. The structure, composition and geometry of SBOPA and SBPBA and their metal complexes were confirmed by spectral techniques (FT-IR, and 1H NMR), elemental analysis, and electronic spectra magnetic moment. On the basis of FT-IR, 1HNMR, electronic spectra and magnetic moment values Mn(II), Co(II) and Ni(II) ion were found to have octahedral geometry while Cu(II) and Zn(II) were found to be square-planar in nature. Thermogravimetric analysis (TGA) was used to evaluate their thermal behaviour and Cu(II)-SBOPA and Cu(II)-SBPBA were found to be thermally most stable. The polymeric Schiff base ligands, SBOPA and SBPBA and their metal complexes have also been screened for their plausible antimicrobial activity. Tetracyclin and Miconazole were used as standard drug to study the antibacterial and antifungal activity respectively. The Cu(II)-SBOPA and Cu(II)-SBPBA were found to be most potent antimicrobial agents.

Herbo-mineral based Schiff base ligand and its metal complexes: Synthesis, characterization, catalytic potential and biological applications.

Schiff base ligand, (L), derived from condensation reaction of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, (curcumin), with pyridine-3-carboxamide, (nicotinamide), and its complexes of Co(II), Ni(II) and Cu(II) ions, containing 1,10-phenanthroline as auxiliary ligand were synthesized and characterized by various physico-chemical techniques. From the micro analytical data, the stoichiometry of the complexes 1:1 (metal: ligand) was ascertained. The Co(II) and Cu(II) forms octahedral complexes, while the geometric structure around Ni(II) atom can be described as square planar. The catalytic potential of the metal complexes have been evaluated by recording the rate of decomposition of hydrogen peroxide. The results reveal that the percent decomposition of H2O2increases with time and the highest value (50.50%) was recorded for Co(II) complex. The ligand and its complexes were also screened for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes and Pseudomonas aeruginosa. The relative order of antibacterial activity against S. Pyogenes, S. aureus and E. coli is Cu(II)>Ni(II)>Co(II)>(L); while with P. aeruginosa, K. pneumoniae the order of activity is Cu(II)>Co(II)>Ni(II)>(L). The anthelmintic screening was performed using Pheretima posthuma. The order of anthelmintic activity of ligand and its complexes is [(Phen)CuLCl2]>[(Phen)CoLCl2]>[(Phen)NiL]Cl2>(L).

Synthesis, characterization and biocidal activities of Schiff base polychelates containing polyurethane links in the main chain.

The concept of combining metallo-polymers with urethanes offers a versatile approach for the synthesis of new polymeric materials. Polyurethane containing transition metals was synthesized by the reaction of Schiff base metal complex with toluene 2,4 diisocyanate. The proposed structures were confirmed by elemental analysis, (1)H NMR, (13)C NMR and FT-IR. The geometry is determined by UV-Visible spectra and magnetic moment measurements, which reveals that the Mn(II), Co(II) and Ni(II) complexes have octahedral geometry while square planer geometry is reported for Cu(II) and tetrahedral for Zn(II) complex. The antimicrobial activities are determined using the agar well diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans and Aspergillus flavus (yeast). All the polymeric metal complexes show comparatively good biocidal activity, which is further enhanced after polymerization.

Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes.

A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, (1)H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand.

Coordination polymer: synthesis, spectral characterization and thermal behaviour of starch-urea based biodegradable polymer and its polymer metal complexes.

A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), (1)H-NMR spectroscopy, (13)C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry, while Cu(II) and Zn(II) complexes show square planar and tetrahedral geometry, respectively. The thermogravimetric analysis revealed that all the polymeric metal complexes are more thermally stable than the parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM standards of biodegradable polymers by CO(2) evolution method.

Synthesis, characterization, and biocide properties of semicarbazide-formaldehyde resin and its polymer metal complexes.

Semicarbazide-formaldehyde resin (SFRs) was prepared by the condensation of semicarbazide with formaldehyde in an acidic medium and its polymer metal complexes were prepared with transition metal ions. All the synthesized polymers were characterized by elemental analysis, FTIR, (1)H NMR, (13)C NMR, electronic spectroscopy, magnetic moment measurement and thermogravimetric analyses. The percentage of metal in all the polymer metal complexes was found to be consistent with 2:1 (resin: metal) stoichiometry. The magnetic susceptibility measurement and electronic spectra of all the polymer metal complexes confirmed the geometry of the complexes. All the synthesized polymeric compounds have been screened in vitro against Bacillus subtilis, Staphylococcus aureus (Gram-positive) and Escherichia coli, Salmonella typhi (Gram-negative) using shaking flask method. The entire polymer metal complexes showed excellent anti-bacterial activity and low toxicity when compared with their parental polymeric resin. The anti-bacterial activity and toxicity of the entire synthesized compound is significant and they can be used as antimicrobial as well as anticancer agents for mammals in future.

New class of anti-microbial agents: synthesis, characterization, and anti-microbial activities of metal chelated polyurea.

A new class of metal chelated polyurea have been synthesized by the reaction of toluene 2,4-diisocyanate (TDI) with chelated Schiff base diamines. The synthesized polyurea have been characterized by analytical, spectral, and thermal analysis. The results of TGA ascribed that [Cu(II)-PoU(A)] show better heat resistant properties than other metals chelated polyurea. The antibacterial activities of all the synthesized polymers were determined using the shaking flask method, where 30 mg/mL concentrations of each compound were tested against 10(5) CFU/mL solutions of S. aureus, E. coli, B. subtillis, S. typhi. The number of viable bacteria was calculated by using the spread plate method on agar plates and the number of viable bacteria was counted after 24 h of incubation period at 37 degrees C. All the polymers showed good antibacterial activity. The Cu(II) chelated polyurea show higher zone of inhibition then other due to higher stability constant and may be used in biomedical applications.