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Structure-Property Relationships in Crystal Structures of Polar Molecules.

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Presentation on theme: "Structure-Property Relationships in Crystal Structures of Polar Molecules."— Presentation transcript:

1 Structure-Property Relationships in Crystal Structures of Polar Molecules

2 Aims Search for patterns in crystal structures of functionalised organic molecules Influence of electrostatic multi-polar interactions Part of overall group interest in crystal packing interactions Develop procedures for design of systems with electro-optical interactions

3 Background Nonlinear optical (NLO) materials have properties useful for photonic materials Primary requisite for NLO material is non- centrosymmetry Easy (relatively!) to design in at molecular level; hard to design in at macromolecular level H-bonding less prevalent for these materials (unlike pharmaceuticals) Thus electrostatic interactions assume relatively greater importance

4 E-Science Part of the E-science Comb-e-Chem project Database mining to search for patterns in structures e.g. CSD But - CSD not large enough to allow useful knowledge to be gained So – need to accumulate new data to provide detailed information to identify patterns in structures

5 Data Set for Project Data set of polymorphic clusters where at least one member is non-centrosymmetric Constructed from CSD v5.23 (April 2002) 835 hits grouped into 258 polymorphic clusters each comprising of 2-3 different polymorphs

6 Modelling of Electrostatic Potential Model electrostatic potential map and partial charge distribution Molecular modelling package – Spartan 02 for Windows Single point energy calculation using Hartree-Fock model with 3-21G (*) basis set Computationally cheap, but may not be sophisticated enough

7 Spartan Results

8 Further Computational Modelling Attempt to model solid state using coordination sphere failed – beyond limits of software A set of polymorphs compared using Synthon (Dr. T. Gelbrich) A subset of these polymorphs compared using Voron (Dr. S. Christensen) Synthon data has shown similarities between some polymorphs compared Voron data is still being analysed

9 Further Work Coordinate data missing from CSD, so need to synthesise / recrystallise compounds to fill in gaps Carry out further comparisons using Synthon and Voron in combination with electrostatic potential studies Recrystallise compounds from data set under strong D.C. fields

10 Acknowledgements Prof. Mike Hursthouse The Group – Prof. Chris Frampton, Dr. Simon Coles, Dr. Mark Light, Dr. Ann Bingham, Dr. Pete Horton, Dr. Thomas Gelbrich, Dr. Stefan Christensen, Dr. Yang Li, Dr. Ranko Vrlej, Dave Hughes, Suzanna Ward EPSRC E-Science project

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