Effects of turn-structure on folding and entanglement in artificial molecular overhand knots.

From Europe PMC via Jisc Publications RouterHistory: ppub 2020-12-01, epub 2020-12-08Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; Grant(s): EP/P027067/1, EP/P001386/1Funder: European Research Council; Grant(s): 786630The length and constitution of spacers linking three 2,6-pyridinedicarboxamide units in a molecular strand influence the tightness of the resulting overhand (open-trefoil) knot that the strand folds into in the presence of lanthanide(iii) ions. The use of β-hairpin forming motifs as linkers enables a metal-coordinated pseudopeptide with a knotted tertiary structure to be generated. The resulting pseudopeptide knot has one of the highest backbone-to-crossing ratios (BCR)-a measure of knot tightness (a high value corresponding to looseness)-for a synthetic molecular knot to date. Preorganization in the crossing-free turn section of the knot affects aromatic stacking interactions close to the crossing region. The metal-coordinated pseudopeptide knot is compared to overhand knots with other linkers of varying tightness and turn preorganization, and the entangled architectures characterized by NMR spectroscopy, ESI-MS, CD spectroscopy and, in one case, X-ray crystallography. The results show how it is possible to program specific conformational properties into different key regions of synthetic molecular knots, opening the way to systems where knotting can be systematically incorporated into peptide-like chains through design

Examining the origin of selectivity in the reaction of racemic alcohols with chiral N-phosphoryl oxazolidinones

A range of known and novel N-phosphoryl oxazolidinones and imidazolidinones were prepared and screened in the kinetic resolution of a range of racemic magnesium chloroalkoxides. Models are proposed to account for the enantioselectivity achieved based on a combination of chiral relay effects, generation of transient stereochemistry and the structure of the intermediate magnesium alkoxide

I Cook, Therefore I Am a Chemist

Though I didn’t realize it at the time, my love of chemistry began very early in life by cooking and baking with my family. We will discuss how what takes place in the kitchen is simply a chemical process or reaction to make food more edible, nutritious and enjoyable. Some of the changes that occur to different foods upon heating, mixing or cooling will be explored using the scientific method

Asymmetric phosphorylation through catalytic P(III) phosphoramidite transfer: Enantioselective synthesis of d-myo-inositol-6-phosphate

Despite the ubiquitous use of phosphoramidite chemistry in the synthesis of biophosphates, catalytic asymmetric phosphoramidite transfer remains largely unexplored for phosphate ester synthesis. We have discovered that a tetrazole-functionalized peptide, in the presence of 10-Å molecular sieves, functions as an enantioselective catalyst for phosphite transfer. This chemistry in turn has been used as the key step in a streamlined synthesis of myo-inositol-6-phosphate. Mechanistic insights implicate phosphate as a directing group for a highly selective kinetic resolution of a protected inositol monophosphate. This work represents a distinct and efficient method for the selective catalytic phosphorylation of natural products