Green Synthesis of Metal-Organic Framework Bacterial Cellulose Nanocomposites for Separation Applications.

Metal organic frameworks (MOFs) are porous crystalline materials that can be designed to act as selective adsorbents. Due to their high porosity they can possess very high adsorption capacities. However, overcoming the brittleness of these crystalline materials is a challenge for many industrial applications. In order to make use of MOFs for large-scale liquid phase separation processes they can be immobilized on solid supports. For this purpose, nanocellulose can be considered as a promising supporting material due to its high flexibility and biocompatibility. In this study a novel flexible nanocellulose MOF composite material was synthesised in aqueous media by a novel and straightforward in situ one-pot green method. The material consisted of MOF particles of the type MIL-100(Fe) (from Material Institute de Lavoisier, containing Fe(III) 1,3,5-benzenetricarboxylate) immobilized onto bacterial cellulose (BC) nanofibers. The novel nanocomposite material was applied to efficiently separate arsenic and Rhodamine B from aqueous solution, achieving adsorption capacities of 4.81, and 2.77 mg g‒1, respectively. The adsorption process could be well modelled by the nonlinear pseudo-second-order fitting.

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters - diastereomeric control of enantioselectivity.

Twenty clusters of the general formula [(µ-H)2Ru3(µ3-S)(CO)7(µ-P-P*)] (P-P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(µ-H)2Ru3(µ3-S)(CO)7(µ-P-P*)] has been investigated by DFT calculations.

Incorporation of strontium and europium in crystals of α-calcium isosaccharinate.

The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5-13.5) and low temperature (< 7 °C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in α-calcium isosaccharinate (ISA) under alkaline conditions (pH ∼10) at 5 °C and 50 °C have been studied. The results show that strontium and europium are incorporated into α-Ca(ISA)2 when crystallized both at 5 °C and 50 °C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 °C rendered the phase compositions Ca0.986Eu0.014(ISA)2 (2.4% of Eu(ISA)3 by mass) and Ca0.98Sr0.02(ISA)2 (2.2% of Sr(ISA)2 by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)2 crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)2 is expected to contribute to a decreased mobility of these ions in the repository.

Chemical and Photochemical Water Oxidation Mediated by an Efficient Single-Site Ruthenium Catalyst.

Water oxidation is a fundamental step in artificial photosynthesis for solar fuels production. In this study, we report a single-site Ru-based water oxidation catalyst, housing a dicarboxylate-benzimidazole ligand, that mediates both chemical and light-driven oxidation of water efficiently under neutral conditions. The importance of the incorporation of the negatively charged ligand framework is manifested in the low redox potentials of the developed complex, which allows water oxidation to be driven by the mild one-electron oxidant [Ru(bpy)3 ]3+ (bpy=2,2'-bipyridine). Furthermore, combined experimental and DFT studies provide insight into the mechanistic details of the catalytic cycle.

Catalyst-solvent interactions in a dinuclear Ru-based water oxidation catalyst.

Photocatalytic water oxidation represents a key process in conversion of solar energy into fuels and can be facilitated by the use of molecular transition metal-based catalysts. A novel straightforward approach for covalent linking of the catalytic units to other moieties is demonstrated by preparation of a dinuclear complex containing two [Ru(pdc)(pic)3]-derived units (pdc = 2,6-pyridinedicarboxylate, pic = 4-picoline). The activity of this complex towards chemical and photochemical oxidation of water was evaluated and a detailed insight is given into the interactions between the catalyst and acetonitrile, a common co-solvent employed to increase solubility of water oxidation catalysts. The solvent-induced transformations were studied by electrochemical and spectroscopic techniques and the relevant quantitative parameters were extracted.

Water oxidation catalyzed by molecular di- and nonanuclear Fe complexes: importance of a proper ligand framework.

The synthesis of two molecular iron complexes, a dinuclear iron(iii,iii) complex and a nonanuclear iron complex, based on the dinucleating ligand 2,2'-(2-hydroxy-5-methyl-1,3-phenylene)bis(1H-benzo[d]imidazole-4-carboxylic acid) is described. The two iron complexes were found to drive the oxidation of water by the one-electron oxidant [Ru(bpy)3](3+).

Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis.

Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(µ-H)2Ru3(µ3-S)(CO)7(µ-P-P*)] (P-P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations.

[µ-Bis(diphenyl-phosphan-yl-κP)methane]-deca-carbonyl-tri-µ-hydrido-trirhenium(I)(3 Re-Re) dichloromethane solvate.

In the title compound, [Re(3)(µ-H)(3)(C(25)H(22)P(2))(CO)(10)]·CH(2)Cl(2), the three Re atoms form a triangle bearing ten terminal carbonyl groups and three edge-bridging hydrides. The bis-(diphenyl-phosphan-yl)methane ligand bridges two Re atoms. Neglecting the Re-Re inter-actions, each Re atom is in a slightly distorted octa-hedral coordination environment. The dichloro-methane solvent mol-ecule is disordered over two sets of sites with fixed occupancies of 0.6 and 0.4.