Grid-based dynamic electronic publication: A case study using combined experiment and simulation studies of crown ethers at the air/water interface.
Esther R Rousay, Hongchen Fu, Jamie M Robinson, Jeremy G Frey, Jonathan W Essex
School of Chemistry, University of Southampton,
Highfield, Southampton, SO17 1BJ, UK

Abstract The Publication@Source Paradigm and Challenges Body Molecular Dynamics Simulations Comparisons and Conclusions Acknowledgements Appendix:The TriScapeRDF browser References Glossary Search
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The difference between the concentration dependence of surface excess obtained from the surface tension experiments and the adsorption isotherm obtained from the SHG work is surprising. Initially we suspected that the difference was due to changing conformations of the crown with concentration, this is not indicated by the polarisation dependence. However, as indicated above the SHG polarisation results suggest that the crown ether is only weakly aligned and it is therefore possible that the degree of alignment is changing with concentration, as in the weak limit these changes would not be reflected in the shape of the polarisation curves only the magnitude of the SHG responce. The simulations suggest that the weak limit is not fully obtained but also suggest that the crown ether is present in two distinct conformations, which may lie in different regions of the interface. Further simulations are underway to predict the surface tension at different surface concentrations of the crown ether. Further analysis of the simulation will be able to demonstrate if any correlation between the ?tilt? and ?twist? angles of the benzene unit relative to the interface exist. The incorporation of improved ab initio calculations of the molecular hyperpolarisibilities and then averaging them using the simulation results will also provide a better comparison between experiment and theory.

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