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Teaching an Old Diffractometer New Tricks - RSC Twitter Posters 2021Using an older Rigaku Spider diffractometer for total scattering and PDF analysis.

Poster presented at the BCA Spring Meeting 2021.

The removal of organophosphorus (OP) herbicides fromwater hasbeen studied using adsorptive removal, chemical oxidation, electrooxidation,enzymatic degradation, and photodegradation. The OP herbicide glyphosate(GP) is one of the most used herbicides worldwide, leading to excessGP in wastewater and soil. GP is commonly broken down in environmentalconditions to compounds such as aminomethylphosphonic acid (AMPA)or sarcosine, with AMPA having a longer half-life and similar toxicityto GP. Metal-organic frameworks (MOFs) are excellent materialsfor purifying OP herbicides from water due to their ability to combineadsorption and photoactivity within one material. Herein, we reportthe use of a robust Zr-based MOF with a meta-carboranecarboxylate ligand ( mCB-MOF-2) to examinethe adsorption and photodegradation of GP. The maximum adsorptioncapacity of mCB-MOF-2 for GP was determinedto be 11.4 mmol/g. Non-covalent intermolecular forces between thecarborane-based ligand and GP within the micropores of mCB-MOF-2 are thought to be responsible for strongbinding affinity and capture of GP. After 24 h of irradiation withultraviolet-visible (UV-vis) light, mCB-MOF-2 selectively converts 69% of GP to sarcosine and orthophosphate,following the C-P lyase enzymatic pathway and biomimeticallyphotodegrading GP. Circumventing the production of AMPA is desirable,as it has a longer half-life and similar toxicity to GP. The exceptionaladsorption capacity of GP by mCB-MOF-2 and its biomimetic photodegradation to non-toxic sarcosine makeit a promising material for removing OP herbicides from water.

A new macrocyclic receptor incorporating a thiourea moiety has been synthesised. Crystal structures of the macrocycle showed that the receptor has a rigid backbone but the thiourea moiety can orientate itself to bind to a DMSO solvent molecule. Force-field (MMFFs) calculations were performed to model the macrocycle and its binding properties with respect to N-protected amino acids, which were measured experimentally by NMR titration. Binding free energies were calculated by using the mode integration algorithm (MINTA) or free-energy perturbation (FEP). Excellent qualitative agreement with experiment was obtained. To further exploit the accuracy of the free-energy predictions for this system, the faster free-energy algorithm MINTA was used as a prediction tool to test the binding affinity of the macrocycle towards a series of several other amino acid derivatives, which speeded up considerably the screening process and reduced laboratory costs.

In the present paper we report our latest efforts in pushing the boundaries of synergistic catalysis. We propose the use of 3 different catalytic cycles working in concert for the formation of cis cyclopropane derivatives of benzoxazoles with excellent stereoselectivities. This is the proof of concept that synergistic catalysis could be successfully used in cascade reactions.