The synthesis and characterization of copper-based metal–organic framework/graphite oxide composites

Photocatalytic hydrogen peroxide (H2O2) production from water and molecular oxygen (O2) by sunlight is a promising strategy for green, safe, and sustainable H2O2 synthesis. We prepared graphitic carbon nitride (g-C3N4) doped with electron-deficient biphenyl diimide (BDI) units by a simple calcination procedure. The g-C3N4/BDI catalyst, when photoirradiated by visible light (λ >420 nm) in pure water with O2, successfully promotes water oxidation by the photogenerated valence band holes and selective two-electron reduction of O2 by the conduction band electrons, resulting in successful production of millimolar levels of H2O2. Electrochemical analysis, Raman spectroscopy, and ab initio calculation results revealed that, upon photoexcitation of the catalyst, the photogenerated positive holes are localized on the BDI unit while the conduction band electrons are localized on the melem unit. This spatial charge separation suppresses rapid recombination of the hole–electron pairs and facilitates efficient H2O2 pr...

Graphitic Carbon Nitride Doped with Biphenyl Diimide: Efficient Photocatalyst for Hydrogen Peroxide Production from Water and Molecular Oxygen by Sunlight

Metal–organic frameworks (MOFs), besides being porous materials exhibit a very rich chemistry, which can be used for the synthesis of composites and/or the reactive adsorption of toxic gases. In this study, composites of MOFs (MOF-5, HKUST-1 or MIL-100(Fe)) and a graphitic compound (graphite or graphite oxide, GO) were synthesized and tested for the removal of NH3, H2S and NO2 under ambient conditions. The materials were characterized before and after exposure to the target gases by X-ray diffraction, thermogravimetric analysis, N2 sorption measurement and FT-IR spectroscopy. The results indicate that strong chemical bonds exist between the MOF and GO as a result of the coordination between the GO oxygen groups and the MOFs’ metallic centers. Depending on the structure of the MOF, such interactions induce the formation of a new pore space in the interface between the carbon layers and the MOF units, which enhances the physical adsorption capacity of the toxic gases. When unsaturated metallic sites are present in the MOFs, the target gases are also adsorbed via coordination to these centers. Further reaction with the framework leads to the formation of complexes. This is accompanied by the collapse of the MOF structure.

Exploring the coordination chemistry of MOF-graphite oxide composites and their applications as adsorbents.

A novel solution-based approach is presented to process earth-abundant Cu(2)ZnSn(S,Se)(4) absorbers using fully dissolved CZTS precursors in which each of the elemental constituents intermix on a molecular scale This method enables the low-temperature processing of chemically clean kesterite films with excellent homogeneity The high performance of resulting optoelectronic devices represents a chance to extend the impact of CZTS into the next chapter of thin-film solar cells

Novel solution processing of high-efficiency Earth-abundant Cu2 ZnSn(S,Se)4 solar cells.

Electrochemical activation is an effective and simple method to obtain in-situ surface modification of MOF materials away from thermal decomposition However, the impact of the rate and related pha

Expediting in-Situ Electrochemical Activation of Two-DimensionalMetal–Organic Frameworks for Enhanced OER Intrinsic Activityby Iron Incorporation

Some new hydrazinium salts of 2-pyrazinecarboxylate, 2,3-pyrazinedicarboxylate, 3,5-pyrazoledicarboxylate and 4,5-imidazoledicarboxylate have been prepared. The in vitro antibacterial screening of the free acids and their hydrazinium salts has been carried out against Escherichia coli, Salmonella typhiiand Vibrio cholerae. The antibacterial activities of the prepared hydrazinium salts show more promising activity than the corresponding free acids and the standard positive control antibiotic, Co-trimoxazole.

Antimicrobial study of pyrazine, pyrazole and imidazole carboxylic acids and their hydrazinium salts

New hydrazinium salts of benzene tricarboxylic and tetracarboxylic acids: preparation and their thermal studies

Preparation, characterisation and thermal reactivity of transition metal complexes of hydrazine with citric acid

The hydrazinium(1+) metal acetates and malonate dihydrates of the molecular formula [(N2H5)2M(CH3COO)4] and (N2H5)2[M(OOCCH2COO)2(H2O)2] respectively, whereM=Co, Ni or Zn, have been prepared and characterized by chemical analyses, conductance, magnetic, spectral, thermal and X-ray powder diffraction studies. The magnetic moments and electronic spectra indicate that these complexes are of high-spin octahedral variety. The infrared spectra show that the hydrazinium ions are coordinated in the case of acetate complexes, whereas in the malonate complexes the hydrazinium ions are out side the coordination sphere. These complexes undergo exothermic decomposition in the temperature range 150–450°C to give the respective metal oxide as the final residue. The X-ray powder diffraction patterns of the malonate complexes indicate isomorphism among them.

Acetate and malonate complexes of cobalt(II), nickel(II) and zinc(II) with hydrazinium cation

The hydrazinium lanthanide metal complexes of 2-pyrazinecarboxylic acid (HpyzCOO) of the formulae (N2H5)2[Ln(pyzCOO)5]·2H2O, where Ln=La or Ce and (N2H5)3[Ln(pyzCOO)4(H2O)]·2NO3, where Ln=Pr, Nd, Sm or Dy have been synthesized by the addition of an aqueous solution of the corresponding metal nitrate hydrates to an aqueous mixture of the respective carboxylic acids and hydrazine hydrate. The in vitro antibacterial screening of the free acid and its metal complexes has been carried out against Escherichia coli, Salmonella typhi and Vibrio cholerae. Antifungal activities of all the synthesized compounds were screened for in vitro growth inhibitory activity against Aspergillus fumigatus and Aspergillus niger by using the disc diffusion method. The antimicrobial activities of the prepared metal complexes show more promising activity than the corresponding free acid, its hydrazinium salts, and the standard control antibiotics, Co-trimoxazole and Carbendazim.

S. Govindarajan

Papers

Antimicrobial study of pyrazine, pyrazole and imidazole carboxylic acids and their hydrazinium salts

New hydrazinium salts of benzene tricarboxylic and tetracarboxylic acids: preparation and their thermal studies

Preparation, characterisation and thermal reactivity of transition metal complexes of hydrazine with citric acid

Acetate and malonate complexes of cobalt(II), nickel(II) and zinc(II) with hydrazinium cation

Antimicrobial study on trivalent lighter rare-earth complexesof 2-pyrazinecarboxylate with hydrazinium cation