Photocatalytic conversion of sugars to 5-hydroxymethylfurfural using aluminium(III) and fulvic acid.

5-hydroxymethylfurfural (HMF) is a valuable and essential platform chemical for establishing a sustainable, eco-friendly fine-chemical and pharmaceutical industry based on biomass. The cost-effective production of HMF from abundant C6 sugars requires mild reaction temperatures and efficient catalysts from naturally abundant materials. Herein, we report how fulvic acid forms complexes with Al ions that exhibit solar absorption and photocatalytic activity for glucose conversion to HMF in one-pot reaction, in good yield (~60%) and at moderate temperatures (80 °C).

Reactions of sulfoxides with reactive oxygen species to reveal the radical chemistry of pollution-derived particulate matter.

The radical reactions of dimethylsulfoxide (DMSO) and tetrahydrothiophene-1-oxide (THTO) with reactive oxygen species (ROS) in the presence of a nitroxide radical scavenger have been evaluated both synthetically and in analytical practice. Fenton-mediated generation of oxygen-centred radicals produced several unusual products that reflect the fragmentation and ring-opening radical mechanisms of DMSO and THTO respectively. Addition of pollution-derived ROS to DMSO/THTO nitroxide solutions produced LC-MS detectable amounts of the same products isolated from the larger-scaled Fenton reactions.

Competition of Hydrogen Bonds and Coordinate Bonds Induces a Reversible Crystal Transformation.

Achieving reversible molecular crystal transformation between coordinate aggregates and hydrogen bonded assemblies has been a challenging task because coordinate bonds are generally much stronger than hydrogen bonds. Recently, we have reported the incorporation of silver ions into the cyanuric acid-melamine (CAM) network, resulting in the formation of a 1D coordination polymer (crystal ) through forming the κN-Ag-κN coordination bonds. In this work, we find crystal will undergo reversible transformation to hydrogen bonded coordinate units (crystal ) through the breaking of coordinate chains and then the addition of CAM hydrogen bonding motifs into the framework.

Unconventional, Gram-Scale Synthesis of a Molecular Dimer Organic Luminogen with Aggregation-Induced Emission.

Organic luminogens have been widely used in optoelectronic devices, bioimaging, and sensing. Conventionally, the synthesis of organic luminogens requires sophisticated, multistep design, reaction, and isolation procedures. Herein, the products of the melt-phase condensation of benzoguanamine (BG; 2,4-diamino-6-phenyl-1,3,5-triazine) at 370-410 °C display interesting reaction-condition-dependent luminescence properties, including photoluminescence (PL) at a variety of wavelengths in the visible spectrum and quantum efficiencies (PLQE) of up to 58% in the powder form.

Nanostructure Shape-Effects in ZnO heterogeneous photocatalysis.

Selective oxidation of alcohols is an essential reaction for fine chemical production. Here, the photocatalytic oxidation of benzyl alcohol by zinc oxide (ZnO) nanocrystals was investigated to clarify the mechanism of selective oxidation with this process. Reactivity when in contact with three distinct ZnO nanocrystal shapes: nanocones, nanorods and nanoplates, was studied in order to compare crystal facet-specific effects in the reaction system.

Charge Neutral [CuL] and [PdL] Metallocycles: Self-Assembly, Aggregation, and Catalysis.

A range of morphologically distinct metallosupramolecular Cu(II) and Pd(II) complexes has been constructed, based on the tritopic ligand 1,1',1″-(benzene-1,3,5-triyl)tris(4,4-dimethylpentane-1,3-dione) (H). By control of the reaction conditions, it is possible to generate distinct coordination assemblies possessing either macrocyclic or polymeric structures and more importantly distinct activity in catalysis of the Suzuki-Miyaura cross-coupling.

The kinetics and mechanism of interconversion within a system of [FeL] helicates and [FeL] cages.

Nature builds simple molecules into highly complex assemblies, which are involved in all fundamental processes of life. Some of the most intriguing biological assemblies are those that can be precisely reconfigured to achieve different functions using the same building blocks. Understanding the reconfiguration of synthetic self-assembled systems will allow us to better understand the complexity of proteins and design useful artificial chemical systems.

Comment on "Trimorphs of 4-bromophenyl 4-bromobenzoate. Elastic, brittle, plastic" by S. Saha and G. R. Desiraju, , 2018, , 6348.

A re-refinement of the published but chemically implausible, crystal structure of "Form III" of 4-bromophenyl 4-bromobenzoate shows that it is not a polymorph, but instead a co-crystal containing both 4-bromophenyl 4-bromobenzoate (≈25%) and likely 4-bromophenyl 4-nitrobenzoate (≈75%).

Wavelength-Gated Photochemical Synthesis of Phenalene Diimides.

Herein, we pioneer a wavelength-gated synthesis route to phenalene diimides. Consecutive Diels-Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro-phenalene-1,6-diol diimides via 5-formyl-hexahydro-benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82-99 % yield) and exhibit excellent diastereoselectivity (62-98 % d.

Crystal Transformation from the Incorporation of Coordinate Bonds into a Hydrogen-Bonded Network Yields Robust Free-Standing Supramolecular Membranes.

In this work, we report on the synthesis of a free-standing, macroscopic robust supramolecular membrane by introducing silver-nitrogen coordinate bonding into preorganized, supramolecular hydrogen-bonded cyanuric acid-melamine (CAM) crystals. With the assistance of ammonia, silver ions competitively replace two of the three hydrogen atoms from cyanuric acid resulting in the transformation from short CAM nanorods to long CAM-Ag nanofibers (length over 1000 μm), accompanied by tautomerization of cyanuric acid. The single crystal structure of the CAM-Ag nanofibers is solved in the space group 1, with the asymmetric unit containing eight silver atoms, four melamine and four cyanuric acid molecules, which generate 1D coordination polymer chains consisting of alternating melamine and dianionic cyanurate ligands linked via silver-nitrogen bonds.

Selective hydroxylation of 1,8- and 1,4-cineole using bacterial P450 variants.

This study has evaluated the use of the P450 metalloenzymes CYP176A1, CYP101A1 and CYP102A1, together with engineered protein variants of CYP101A1 and CYP102A1, to alter the regioselectivity of 1,8- and 1,4-cineole hydroxylation. CYP176A1 was less selective for 1,4-cineole oxidation when compared to its preferred substrate, 1,8-cineole. The CYP102A1 variants significantly improved the activity over the WT enzyme for oxidation of 1,4- and 1,8-cineole.

Elastically Flexible Crystals have Disparate Mechanisms of Molecular Movement Induced by Strain and Heat.

Elastically flexible crystals form an emerging class of materials that exhibit a range of notable properties. The mechanism of thermal expansion in flexible crystals of bis(acetylacetonato)copper(II) is compared with the mechanism of molecular motion induced by bending and it is demonstrated that the two mechanisms are distinct. Upon bending, individual molecules within the crystal structure reversibly rotate, while thermal expansion results predominantly in an increase in intermolecular separations with only minor changes to molecular orientation through rotation.

A three-dimensional cubic halogen-bonded network.

The rational, deliberate design of supramolecular architectures is of great importance for the discovery of complex materials. A three-dimensional cubic halogen-bonded network has been prepared by combination of an octahedral metal-containing halogen bond acceptor and a linear ditopic donor. This material displays α-Po pcu topology and is seven-fold interpenetrated.

Reversible Pressure-Controlled Depolymerization of a Copper(II)-Containing Coordination Polymer.

A unique pressure-induced Cu-N bond breaking/bond forming reaction is reported. The variation of pressure on a single crystal of a one-dimensional copper- (II)-containing coordination polymer (Cu L (1-methylpiperazine) ] , where H L is 1,1'-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione)), was monitored using single crystal X-ray diffraction with the aid of a diamond anvil cell. At a very low elevated pressure (≈0.

Interactions between Chitosan and Alginate Dialdehyde Biopolymers and Their Layer-by-Layer Assemblies.

Biopolymers are researched extensively for their applications in biomaterials science and drug delivery including structures and complexes of more than one polymer. Chemical characterization of complexes formed between chitosan (CHI) and alginate dialdehyde (ADA) biopolymers established that while electrostatic interactions dominate (as determined from X-ray photoelectron spectroscopy (XPS)) covalent cross-linking between these biopolymers also contribute to their stability (evidenced from immersion in salt solution). It was furthermore found that imine bond formation could not be directly detected by any of the techniques XPS, FTIR, (1)H NMR, or fluorescence.