A 400 MHz NMR spectrometer to support chemistry at Sheffield

NMR spectroscopy is an essential technique for characterising new compounds and materials and is a core facility in any department undertaking synthetic chemistry. A recent series of new appointments in the chemistry department at Sheffield, and a range of new projects being undertaken, has resulted in a 100% increase in the demand on our elderly suite of machines in the last 5 years. This application is for a 400 MHz instrument which will be dedicated in particular to non-routine experiments (nuclei other than 1H or 13C; two-dimensional experiments, especially involving different nuclei such as 1H/19F; diffusion studies on macromolecules and polymers; variable-temperature analyses) for which the workhorse fast-turnaround service machine cannot be spared.Studies to be undertakne on the new instrument include(1) Examination of the host-guest chemistry of large positively-charged cage-like molecules which bind negatively charged species in their central cavities;(2) Examination of the solution structure of chiral organolithium reagents (essential intermediates in organic chemistry), and measurement of the rate at which the optical isomers interconvert;(3) Measurements of many properties of new polymeric materials, such as the rates at which their form; the composition of monomer components in them; the size distibution of the polymeric molecules in solution; the degree of swelling of micelles due to changes in acidity.(4) Measurements on the solution structures and rates of decomposition of metal carbonyl complexes which have pharmacetical applications associated with the slow release of CO 'in vivo'(5) Accurate determination of the strengths of weak interactions (hydrogen bonds, intermolecular F---F contacts) in solution at different temperatures(6) Measurement of very early events in the process of crystallisation, whereby molecules in solution begin to associate into oligomeric assemblies which act as 'nucleation points' for subsequent growth of crystals.(7) Examination of the solution structures, sizes, and rates of formation of large multi-porphyrin assemblies which have unusual photophysical properties.