No abstract

A new chiral hydrogen-bonded organic framework (HOF) denoted as ZIOC-1 based on a l-prolineamide substituted diarylacetylene dicarboxylic acid (3,3′-ethyne-1,2-diylbis­[6-(l-prolylamino)­benzoic acid]) has been synthesized and structurally characterized. Crystal structures of two forms of ZIOC-1, i.e., anhydrous and dihydrate phases, were identified by powder X-ray analysis. It was found that the novel HOF material demonstrated a framework flexibility: its crystalline phases transform reversibly into each other by a change in either humidity or ambient temperature. This fact in conjunction with the retention of crystal identity to the temperature as high as 265 °C indicates a robustness of the framework formed by a hydrogen bonding system. The catalytic performance of the synthesized HOF was probed in aldol condensation and Michael reaction.

The use of available renewable sources of raw materials for the production of various organic compounds has long been undoubted and recognized throughout the world. However, the development of efficient “green” catalytic technologies for the processing of bioavailable compounds, namely, the synthesis of catalysts and the selection of optimal process conditions, has become a real challenge for researchers nowadays. In this work, 2,5-bis­(hydroxymethyl)­furan, an intermediate for the production of a number of biobased polymer materials, was obtained by hydrogenation of 5-hydroxymethylfurfural in a yield close to quantitative at room temperature and atmospheric pressure in the presence of a catalytic system with 1% wt of platinum as an active phase supported on ceria–zirconia mixed oxide. On the low-loaded 0.25% Pt/CeO2–ZrO2 catalyst, the yield of the desired alcohol as high as 87% has been achieved after a slight increase of H2 pressure from 0.1 to 0.5 MPa.

Novel reactive materials for catalytic degradation of chlorinated organic compounds in water at ambient conditions have been prepared on the basis of silica-supported Pd-Fe nanoparticles. Nanoscale Fe-Pd particles were synthesized inside porous silica supports using (NH 4 ) 3 [Fe(C 2 O 4 ) 3 ] and [Pd(NH 3 ) 4 ]Cl 2 or Pd acetate as reaction precursors. According to temperature programmed reduction (TPR) studies, Pd introduction decreased the reduction temperature of the supported Fe n+ species and nearly complete reduction with H 2 was observed at 400 °C. The successful surface loading with Pd was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Characterization of the samples by X-ray diffraction (XRD) and X-ray absorption near-edge structure + extended X-ray absorption fine structure (XANES + EXAFS) verified the presence of highly dispersed Pd 0 , Pd x Fe 1-x and Fe 0 phases. Reduction of the supported precursors in hydrogen resulted in materials that were highly active in perchloroethene (PCE) degradation and 2-chlorobiphenyl (2-ClBP) dechlorination. It was found that highly dispersed amorphous Fe-Pd bimetallic nanoparticles on silica support showed superior catalytic activity against PCE dechlorination in comparison to the free-standing Fe-Pd nanoparticles. For the samples with the same Fe content, the conversion of chlorinated organics as well as the stability increased with the Pd loading, e.g., the most effective degradation of PCEs and 2-ClBP was achieved at a Pd loading of 2.3-3.2 wt. %.

Nowadays, there is a demand in the production of nontoxic multifunctional magnetic materials possessing both high colloidal stability in water solutions and high magnetization. In this work, a series of water-dispersible natural humate-polyanion coated superparamagnetic magnetite nanoparticles has been synthesized via microwave-assisted synthesis without the use of inert atmosphere. An impact of a biocompatible humate-anion as a coating agent on the structural and physical properties of nanoparticles has been established. The injection of humate-polyanion at various synthesis stages leads to differences in the physical properties of the obtained nanomaterials. Depending on the synthesis protocol, nanoparticles are characterized by improved monodispersity, smaller crystallite and grain size (up to 8.2 nm), a shift in the point of zero charge (6.4 pH), enhanced colloidal stability in model solutions, and enhanced magnetization (80 emu g−1).