Fe3+-bis-ethylenediamine complex bridged periodic mesoporous organosilica for the efficient removal of arsenate and chromate

The direct removal of arsenate (AsO43−) and chromate (CrO42−) from water were achieved using a Fe3+-bis-ethylenediamine complex-bridged periodic mesoporous organosilica with a 20% organosilane content (Fe-EDPMO-20). The bridged Fe3+-bis-ethylenediamine complex was introduced to the pore wall of the PMO by combining the pre-complexation and co-condensation processes. N,N′-bis[3-(triethoxysilyl)propyl]ethylenediamine (TESEN) and tetramethyl orthosilicate (TMOS) as silica precursors were used with cetyltrimethylammonium bromide (CTABr) as a surfactant under basic conditions for the preparation of highly ordered Fe-EDPMO-20. Transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurements confirmed that the Fe-EDPMO-20 had an ordered hexagonal p6mm mesostructure. The material had a Brunauer-Emmett-Teller surface area of 734 m2 g−1, pore diameter of 2.6 nm, and pore volume of 0.61 cm3 g−1. UV-vis and X-ray photoelectron spectroscopy confirmed that Fe3+ was embedded in the coordination site by the nitrogen atoms from ethylenediamine. The adsorption efficiencies of arsenate and chromate ions by Fe-EDPMO-20 were examined as a function of pH, stirring time, amount of adsorbent, and initial concentration of metal ion solution. The maximum adsorption for arsenate and chromate were 156 and 102 mg g−1 within 6 and 24 h, respectively, at pH 4.

Ecofriendly preparation of graphene sheets decorated with an ethylenediamine copper(ii) complex composite modified electrode for the selective detection of hydroquinone in water

A reduced graphene oxide decorated copper(ii) ethylenediamine complex composite modified electrode was applied for the electrochemical determination of hydroquinone.

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

The search for copper catalysts able to perform effectively click reactions in water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II)–EDA (EDA = ethylenediamine) complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer, has been synthesized and characterized by different techniques including single crystal X-ray diffraction. Highly efficient photoreduction was demonstrated when solutions of 1 in hydrogen atom donating solvents, such as THF or MeOH, were exposed to UVA radiation (350–400 nm) provided by a low pressure mercury lamp (type TLC = thin-layer chromatography, 365 nm), or by a 23 W fluorescent bulb, or by ambient/sunlight. In water, a much poorer hydrogen atom donating solvent, the photoreduction of 1 proved inefficient. Interestingly, EPR studies revealed that complex 1 could nonetheless be effectively photoreduced in water when alkynes were present in solution. The catalytic activity of 1 for click reactions involving a range of water-soluble alkynes and azides, in particular saccharides, was tested under various illumination conditions. Complex 1 was found to exhibit a photolatent character, the photogenerated copper(I) being very reactive. On irradiating aqueous reaction mixtures containing 1 mol % of 1 at 365 nm (TLC lamp) for 1 h, click reactions were shown to proceed to full conversion.

Biosynthesized Ag/α-Al2O3 catalyst for ethylene epoxidation: the influence of silver precursors

The catalytic performance of biosynthesized Ag/α-Al2O3 catalysts was strongly affected by silver precursors. Ag catalyst prepared from silver–ethylenediamine complex showed a better activity for ethylene epoxidation than catalysts from AgNO3 and silver–ammonia complex. The influence of silver precursors on the structure, surface state, oxidation property of the catalysts was investigated.