Faiz Rabbani

Binding Strength of Porphyrin−Gold Nanoparticle Hybrids Based on Number and Type of Linker Moieties and a Simple Method To Calculate Inner Filter Effects of Gold Nanoparticles Using Fluorescence Spectroscopy

Gold nanoparticle-porphyrin assemblies were formed by binding functionalized porphyrins to gold nanoparticles (Au-NPs). Spectroscopic properties of hybrids and binding strength of porphyrins to Au-NPs were observed based on number and type of linker moieties using fluorescence spectroscopy. Binding appears to be dependent on number rather than type of linker moieties present on the porphyrin molecules, as tetraaminophenyl porphyrin shows the highest binding among the molecules we studied and causes agglomeration of nanoparticles due to presence of four linker groups. The inner filter effects of Au-NPs are considerably high due to their high extinction coefficient and cause large errors in the evaluation of quenching efficiencies. We have described a very simple method to calculate the inner filter effects of Au-NPs by first loading them with porphyrins and then replacing them with nonfluorescent ligands. The difference in the fluorescence of unbound porphyrins in the presence and absence of Au-NPs describes their inner filter effects.

Cobalt selenium oxohalides: catalysts for water oxidation.

Two new oxohalides Co4Se3O9Cl2 and Co3Se4O10Cl2 have been synthesized by solid state reactions. They crystallize in the orthorhombic space group Pnma and the monoclinic space group C2/m respectively. The crystal structure of the two compounds are made up of similar building blocks; Co4Se3O9Cl2 is made up of [CoO4Cl2], [CoO5Cl] and [SeO3] polyhedra and Co3Se4O10Cl2 is made up of [CoO4Cl2] and [SeO3] polyhedra. As several Co-containing compounds have proved to be good catalysts for water oxidation, the activities of the two new compounds were compared with the previously found oxohalide Co5Se4O12Cl2 in reference to CoO and CoCl2. The one electron oxidant Ru(bpy)3(3+) was used as oxidizing species in a phosphate buffer and it was found that the activities of the oxohalide species were in between CoO and CoCl2. The roles of Cl(-) and PO4(3-) ions are discussed.

A Review on Synthesis, Characterization and Applications of Copper Nanoparticles Using Green Method

To address accosts of this modern age, the synthesis of metal nanoparticles is more important than ever. Copper has been recognized as a nontoxic, safe inorganic material, cheaper antibacterial/ant...

Phase identification and structure determination from multiphase crystalline powder samples by rotation electron diffraction

Phase identification and structure characterization are important in synthetic and materials science. It is difficult to characterize the individual phases from multiphase crystalline powder samples, especially if some of the phases are unknown. This problem can be solved by combining rotation electron diffraction (RED) and powder X-ray diffraction (PXRD). Four phases were identified on the same transmission electron microscopy grid from a multiphase sample in the Ni–Se–O–Cl system, and their structures were solved from the RED data. Phase 1 (NiSeO3) was found in the Inorganic Crystal Structure Database using the information from RED. Phase 2 (Ni3Se4O10Cl2) is an unknown compound, but it is isostructural to Co3Se4O10Cl2, which was recently solved by single-crystal X-ray diffraction. Phase 3 (Ni5Se6O16Cl4H2) and Phase 4 (Ni5Se4O12Cl2) are new compounds. The fact that there are at least four different compounds in the as-synthesized material explains why the phase identification and structure determination could not be done by PXRD alone. The RED method makes phase identification from such multiphase powder samples much easier than would be the case using powder X-ray diffraction. The RED method also makes structure determination of submicrometre-sized crystals from multiphase samples possible.

Synthesis, Crystal Structure and Thermal Decomposition of the New Cadmium Selenite Chloride, Cd4(SeO3)2OCl2

A synthetic study in the Cd-Se-O-Cl system led to formation of the new oxochloride compound Cd4(SeO3)2OCl2 via solid state reactions. The compound crystallizes in the orthorhombic space group Fmmm with cell parameters a = 7.3610(3) Å, b = 15.4936(2) Å, c = 17.5603(3) Å, Z = 8, S = 0.969, F(000) = 2800, R = 0.0185, Rw = 0.0384. Single crystal X-ray data were collected at 293 K. The crystal structure can be considered as layered and the building units are distorted [Cd(1)O6] octahedra, distorted [Cd(2)O8] cubes, irregular [Cd(3)O4Cl2] polyhedra and SeO3E trigonal pyramids. There are two crystallographically unique Cl atoms that both are half occupied. Thermogravimetric studies show that the compound starts to decompose at 500°C. The crystal structure of the new compound is closely related to the previously described compound Cd4(SeO3)2Cl4(H2O).

Synthesis and Crystal Structure of Indium Tellurium Trioxide Bromide

The pale yellow air-stable compound InTeO3Br could be obtained by the reaction of In, TeO2, Te and Br2. The compound crystallizes in the monoclinic crystal system (a=8.2596 (4) Å, b = 6.8752(3) Å, c = 7.1394 (3) Å, β = 103.121 (2)ˆ, Z = 4, space group = P21/c),[1] isotypic to the corresponding chloride compound, InTeO3Cl.[2] The compound forms a layered structure and these layers are separated by van der Waals gaps. InO4Br2 octahedra linked with the TeO3 by sharing common corners are the typical structural building blocks for the title compound.

Biocompatible biodegradable polymeric antibacterial nanoparticles for enhancing the effects of a third-generation cephalosporin against resistant bacteria

Purpose. In the present study, enhancement of the the antibacterial activity of ceftriaxone against Gram‐positive (meticillin‐resistant Staphylococcus aureus; MRSA) and Gram‐negative (Escherichia coli) bacteria with a biodegradable polymer was attempted. Methodology. MRSA and E. coli were collected and identified by biochemical and molecular tests. Blank and ceftriaxone‐loaded chitosan nanoparticles (CNPs) were prepared by the ionic gelation method. In vitro antibiotic‐susceptibility studies were performed by disc diffusion, agar well plate method, Etest and time‐kill assay. In vivo activity was assessed using the neutropenic mouse thigh model and cytotoxicity was estimated by MTT (methylthiazolyldiphenyl tetrazolium bromide) assay with the MCF‐7 cancer cell line. Results. MRSA showed 97% and E. coli 83% resistance against ceftriaxone in the disc diffusion test. The isolates showing a ≥1024 mg l−1 MIC value for ceftriaxone were selected for further evaluation. In the agar well plate method, the mean zones of inhibition for blank and ceftriaxone‐loaded CNPs were 17 and 23 mm, respectively, for MRSA isolates and 15 and 25 mm, respectively, for E. coli isolates. In the time‐kill assay, ˜1 log10 to ˜2.5 log10 reduction in viability was seen with both isolates when treated with ceftriaxone‐loaded CNPs over 24 h. The in vivo studies also showed the enhanced antibacterial activity of ceftriaxone‐loaded CNPs, with a 41% reduction in MRSA and a 27% reduction in E. coli burden. A low cytotoxicity of blank and ceftriaxone‐loaded CNPs was seen, with a slight reduction in the percentage viability of cells from 87 to 83% and from 88 to 81%, respectively. Conclusion. The synergistic effect of ceftriaxone‐loaded CNPs is a useful finding for the treatment of MRSA and E. coli infections.

The synthetic cobalt vanadium selenite, Co2V2Se2O11

The crystal structure of dicobalt(II) divanadium(V) diselenium(IV) undecaoxide, Co2V2Se2O11, exhibits a three-dimensional framework, the building units being distorted CoO6 octahedra and VO5 square pyramids arranged so as to form alternate chains along [010]. The framework has channels along [100] and [010] in which the two Ψ-SeO3 E (site symmetries m; E being the 4s 2 lone electron pair of SeIV) tetrahedra reside and connect to the other building blocks. The structure contains corner- and edge-sharing CoO6 octahedra, corner- and edge-sharing VO5 square pyramids and edge-sharing Ψ-SeO3 E tetrahedra. Co2V2Se2O11 is the first oxide containing all the cations CoII, VV and SeIV.

Biosorption potential of natural, pyrolysed and acid-assisted pyrolysed sugarcane bagasse for the removal of lead from contaminated water

Lead (Pb) is a ubiquitous pollutant which poses serious threats to plants, animals and humans once entered into the food chain via contaminated industrial effluents on their discharge into the surface of water bodies and/or geological materials. This study aimed to examine and compare the biosorption potential of natural sugarcane bagasse (NB), pyrolysed sugarcane bagasse (PB) and acid assisted pyrolysed sugarcane bagasse (APB) for the removal of Pb from contaminated water. To explore this objective, a series of batch experiments were conducted at various adsorbent mass (0.25, 0.5, 0.75, 1.0 g per 100 ml contaminated water), initial Pb concentration (7, 15, 30, 60 and 120 ppm), and contact time (7, 15, 30, 60 and 120 min). Results revealed that all the tested bio-sorbents have potential to adsorb and remove Pb ions from the contaminated water. In this regard, APB proved more effective since it removed 98% of Pb from aqueous solution at initial Pb concentration of 7 ppm and mass of 0.25 g per 100 ml of aqueous solution. The respective values in case of NB and PB were 90 and 95%. For a given adsorbent type, Pb adsorption decreased by increasing the mass from 0.25 to 1.0 g per 100 ml of aqueous solution. However, the greatest Pb removal occurred at adsorbent mass of 1.0 g per 100 ml of aqueous solution. Initial Pb concentration had a great impact on Pb adsorption and removal by adsorbent. The former increased and the latter decreased with the increase in initial Pb concentration from seven to 120 ppm. At seven ppm Pb concentration, maximum Pb removal took place irrespective to the adsorbent type. Out of the total Pb adsorption and removal, maximum contribution occurred within 15 min of contact time between the adsorbate and adsorbent, which slightly increased till 30 min, thereafter, it reached to equilibrium. Application of equilibrium isotherm models revealed that our results were better fitted with Freundlich adsorption isotherm model. Overall, and for the reasons detailed above, it is concluded that sugarcane bagasse has capabilities to adsorb and remove Pb ions from contaminated water. Its bio-sorption potential was considerably increased after pyrolysis and acid treatment.

Synthesis, structural and antibacterial study of new silver complex with 3-acetyl-2H chromene-2-one

A new silver complex [Ag(C 11 H 8 O 3 ) 2 ]NO 3 was synthesized by the reaction of silver nitrateand coumarin based ligand (3-acetyl- 2H- chromene-2-one) through solution method. The product was characterized using different analytical techniques like melting point, Infrared spectroscopy, Raman spectroscopy, powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, atomic absorption spectroscopy and mass spectrometry. An antibacterial study of the complex was also studied for its possible use in medical treatment. KEY WORDS : Silver complex, Acetyl coumarin, Vibrational analysis, Antibacterial study Bull. Chem. Soc. Ethiop. 2016 , 30(3), 403-411 DOI: http://dx.doi.org/10.4314/bcse.v30i3.8