H NMR spectroscopic characterisation of HepG2 cells as a model metabolic system for toxicology studies.

The immortalised human hepatocellular HepG2 cell line is commonly used for toxicology studies as an alternative to animal testing due to its characteristic liver-distinctive functions. However, little is known about the baseline metabolic changes within these cells upon toxin exposure. We have applied H Nuclear Magnetic Resonance (NMR) spectroscopy to characterise the biochemical composition of HepG2 cells at baseline and post-exposure to hydrogen peroxide (HO).

Visible-Light Driven Control Over Triply and Quadruply Hydrogen-Bonded Supramolecular Assemblies.

Supramolecular polymers offer tremendous potential to produce new "smart" materials, however, there remains a need to develop systems that are responsive to external stimuli. In this work, visible-light responsive hydrogen-bonded supramolecular polymers comprising photoresponsive supramolecular synthons (I-III) consisting of two hydrogen bonding motifs (HBMs) connected by a central ortho-tetrafluorinated azobenzene have been characterized by DOSY NMR and viscometry. Comparison of different hydrogen-bonding motifs reveals that assembly in the low and high concentration regimes is strongly influenced by the strength of association between the HBMs.

Direct Detection of Hydrogen Bonds in Supramolecular Systems Using H-N Heteronuclear Multiple Quantum Coherence Spectroscopy.

Hydrogen-bonded supramolecular systems are usually characterized in solution through analysis of NMR data such as complexation-induced shifts and nuclear Overhauser effects (nOe). Routine direct detection of hydrogen bonding particularly in multicomponent mixtures, even with the aid of 2D NMR experiments for full assignment, is more challenging. We describe an elementary rapid H-N HMQC NMR experiment which addresses these challenges without the need for complex pulse sequences.

A chiral interlocking auxiliary strategy for the synthesis of mechanically planar chiral rotaxanes.

Rotaxanes can display molecular chirality solely due to the mechanical bond between the axle and encircling macrocycle without the presence of covalent stereogenic units. However, the synthesis of such molecules remains challenging. We have discovered a combination of reaction partners that function as a chiral interlocking auxiliary to both orientate a macrocycle and, effectively, load it onto a new axle.