Structural Chemistry and Spectroscopy
The Structural Chemistry and Spectroscopy Group aims to establish a
quantitative framework by which to understand and appreciate the static and
dynamical properties of molecular materials and of their chemical reactions.
These materials range from single multi-component molecules to intricate
layered architectures and to biologically-related catalytic residues.
Advanced synthetic chemistry is applied to construct rationally-designed supermolecules and supramolecular entities. Spectroscopic tools include X-ray diffraction, multi-nuclear NMR spectroscopy, laser-induced fluorescence, stopped-flow spectrophotometry and fast transient absorption measurements, supported by Stark-effect spectroscopy and electrochemistry. Much of this research seeks to examine how the absorption of a photon changes the geometry of a molecule or sets up the possibility for energy and/or electron transfer to suitable acceptors.
Other aspects of research cover fundamental understanding of Fe-S cluster reactivity, crystal polymorphism and rational design of molecular materials through crystal engineering. Prominent among the broad range of subdisciplines that provide outlet for this work are artificial photosynthesis, molecular opto-electronics and cluster science.
Computational and quantum chemistry is used routinely to aid understanding of the individual processes. The Structural Chemistry and Spectroscopy Group has made substantial contributions to the advancement of physical chemistry in terms of expressing reaction mechanisms, kinetics and pathways and providing sophisticated protocols for data analysis.
Staff
Dr U Baisch, Dr AC Benniston, Prof W Clegg, Dr JP Hagon, Prof A Harriman, Dr R Harrington, Prof RA Henderson, Dr CY Wills.
Further Information
Understanding the role of reactive oxyradicals in biology is of elementary interest, and necessitates real-time probes for monitoring purposes. Specifically designed molecular sensors have been synthesised for reversible fluorescence detection of reactive oxygen species (ACB) in vitro. Other projects include delving into the excited state deactivation mechanisms of closely-spaced donor-acceptor molecules and the role of exciplexes in deactivation processes. Of paramount interest is the use of NMR spectroscopy (CW) and high-level computational theory (JH) to map electron density distributions in molecular dyads. Highly fluorescence-sensitive nano-scale viscosity probes have been designed and synthesized for multifarious commercial applications.
The fundamental properties of a molecule can be changed substantially by excitation with light, leading to numerous applications based on energy and/or electron transfer. In many cases, such chemistry can be examined by way of time-resolved emission spectroscopy and transient absorption spectroscopy (AH). Current research aims to examine the validity of Förster theory for electronic energy transfer at short separations and to formulate new approaches for solar fuel production by way of bio-inspired molecular arrays that undergo directed electron transfer. Quantum chemical calculations (JH) play an important role in elucidating the underlying reaction mechanisms and intermediate species (JH).
Our research interests lie in crystal engineering (UB) and supramolecular chemistry (WC & RH): the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding in the construction of new crystalline materials or polymorphs. X-ray crystal structure determination, microscopy and synthetic chemistry are combined for this novel approach in materials science. Another important aspect is to explore and to explain the occurrence of polymorphism in metal-organic chemistry and to keep the production costs (energy, solvents, special equipment) of the new compounds as low as possible (Green Chemistry) by using solvent-free solid-solid preparation techniques, such as grinding and liquid-assisted ball-milling. Of particularly interest in this context is the development of new synthetic pathways for a solvent-free design of crystalline lanthanide containing 2D and 3D molecular materials with specific optical or magnetic properties (UB).
The major aim of our work on synthetic Fe-S-based clusters is to help understand the reactivity of proteins containing this type of cluster. Of particular interest are the nitrogenases which bind and transform N2 into NH3 using a Fe-Mo-S cluster as the active site. Although our understanding of the mechanism of nitrogenases is very sophisticated at the protein level, we do not know how N2 (or the so-called alternative substrates, such as CN-, N3-, MeNC, alkynes etc), bind and get transformed at the active site. Our current work on synthetic Fe-S-based clusters is focusing on these problems using a combination of synthetic chemistry and rapid reaction techniques (RAH).