1 / 15

Structure-Property Relationships in Crystal Structures of Polar Molecules

Structure-Property Relationships in Crystal Structures of Polar Molecules. Graham Tizzard Supervisor: Mike Hursthouse. Background. No. of different attractive forces determine packing in molecular crystals London forces, multipolar forces, H- bonding, CT forces

kalea
Download Presentation

Structure-Property Relationships in Crystal Structures of Polar Molecules

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Structure-Property Relationships in Crystal Structures of Polar Molecules Graham Tizzard Supervisor: Mike Hursthouse

  2. Background • No. of different attractive forces determine packing in molecular crystals • London forces, multipolar forces, H- bonding, CT forces • Complex interplay of these + repulsion E → many local minima in crystal lattice E • → Polymorphism - the existence of more than one crystalline form in a substance

  3. Polymorphism & H-bonding • H-bonds: • Highest E interactions in molecular crystals  most important attractive force • Multiple H-bonding sites → different H-bonding topologies → polymorphism • However: • Polymorphism also in systems w.out strong H-bonds (D – H ∙∙∙ A; D = N, O, S; A = N, O, S, Hal) • Weak H-bonds may exist (C – H ∙∙∙ A, C – H ∙∙∙ π) • Importance of H-bonding in defining polymorphism greatly reduced

  4. Aims • Detailed study of weak or non H-bonding systems • Especially those w. non-centrosymmetric polymorphs • V. important for development of materials w. NLO properties • Electrostatic interactions expected to exert greater influence on xtal structure

  5. Dataset • Constructed from Cambridge Structural Database1 (CSD) v5.25 (November 2003) • CSD mined for polymorphic clusters with ≥ one non-centrosymmetric member • 835 ‘hits’ made up of 258 polymorphic clusters each comprising of 2-3 different polymorphs [1] F. H. Allen, Acta Crystallogr., B58, 380-388, 2002..

  6. Analyses • XPac2: • Many polymorphic families of a compound show no similarity when analysed • For those that do ‘structure-forming’ motif may be able to be elucidated from results • Short contact analysis (Mercury v1.2.13) + modelling of electrostatic charges (Spartan’04 for windows4) • Correlation between short contact distances & matching of potentials would suggest these are important in a crystal structure [2] XPac; T. Gelbrich; 2002; University of Southampton, UK. [3] Mercury v1.2.1; CCDC, Cambridge, UK. [4] Spartan’04; Wavefunction, Inc.; Irvine, CA, USA.

  7. 4’-Bromo-trans-1,4-dihydro-4-tritylbiphenyl (BAWSAT) CSD code BAWSAT BAWSAT01 Crystal System orthorhombic monoclinic Space Group (No.) Pnam (62) Pc (7) a / Å 13.012 9.011 b / Å 17.264 16.187 c / Å 10.431 8.463 α / º 90 90 β / º 90 108.98 γ / º 90 90 Cell Volume / Å3 2343.211 1167.309 Z 4 2 Z’ 0.5 1.0 • 2 polymorphs identified from CSD: BAWSAT & BAWSAT01 • BAWSAT01 is non-centrosymmetric Reference [5] [5] [5] A. K. Cheetham, M. C. Grossel, J. M. Newsam; J. Am. Chem. Soc.; 103; 5363; 1981.

  8. XPac Analysis of BAWSAT • Views of BAWSAT along the c-axis (top) & BAWSAT01 between the a and c axes (bottom) • XPac reveals 1d chain along these respective axes common to both crystal structures (green) • In both structures the same chain motif is interspaced (in different ways) between the original (dark green) • Is this a ‘structure-forming’ motif?...

  9. Short Contact & Electrostatic Charge Analyses of BAWSAT BAWSAT01 • Each molecule in BAWSAT01 (top) & BAWSAT (bottom) has short contacts w. 8 neighbours • None of these is particularly strong • ESC & SC data correlation: 4/10 wrt. BAWSAT01; 0 wrt. BAWSAT • Suggests electrostatic interactions unimportant in crystal formation • Other interactions e.g. simple space-filling may dictate these structures. Atom1 Electrostatic charge 1 Atom2 Electrostatic charge 2 Length / Å Length-VdW / Å H8 0.130679 H24 :1 0.136779 2.314 -0.086 H24 0.136779 H8 :2 0.130679 2.314 -0.086 H3 0.097207 Br1 :3 -0.117756 2.97 -0.08 Br1 -0.117756 H3 :4 0.097207 2.97 -0.08 H13 0.104592 H19 :5 0.120092 2.342 -0.058 H19 0.120092 H13 :6 0.104592 2.342 -0.058 H4 0.155091 C28 :7 -0.191035 2.844 -0.056 C28 -0.191035 H4 :8 0.155091 2.844 -0.056 H22 0.136788 H4 :8 0.155091 2.359 -0.041 H4 0.155091 H22 :7 0.136788 2.359 -0.041 BAWSAT Atom1 Electrostatic charge 1 Atom2 Electrostatic charge 2 Length / Å Length-VdW / Å H13 0.104592 H4 :1 0.155091 2.28 -0.12 H4 0.155091 H18 :2 0.104591 2.28 -0.12 H4 0.155091 H13 :3 0.104592 2.28 -0.12 H18 0.104591 H4 :4 0.155091 2.28 -0.12 H3 0.097207 H5 :5 0.097216 2.298 -0.102 H5 0.097216 H3 :6 0.097207 2.298 -0.102 H13 0.104592 H18 :7 0.104591 2.37 -0.03 H18 0.104591 H13 :8 0.104592 2.37 -0.03 H5 0.097216 C3 :5 0.078511 2.898 -0.002 C5 0.078478 H3 :5 0.097207 2.898 -0.002 C3 0.078511 H5 :4 0.097216 2.898 -0.002 H3 0.097207 C5 :4 0.078478 2.898 -0.002

  10. 2-(α-p-Bromophenyl-β-nitroethyl)-cyclohexanone (BPNECH) CSD code BPNECH BPNECH01 Crystal System monoclinic orthorhombic Space Group (No.) P21/c (14) P212121 (19) a / Å 5.630 5.539 b / Å 8.560 8.495 c / Å 30.570 30.777 α / º 90 90 β / º 90.30 90 γ / º 90 90 Cell Volume / Å3 1473.234 1448.175 Z 4 4 Z’ 1.0 1.0 • 2 polymorphs identified from CSD: BPNECH & BPNECH01 • BPNECH01 is non-centrosymmetric Reference [6] [7] [6] M. Calligaris, F. Giordano, L. Randaccio; Ric. Sci., Parte 1; 36; 1333; 1966. [7] D. Seebach, I. M. Lyapkalo, R. Dahinden; Helv Chim Acta; 82; 1829; 1999.

  11. XPac Analysis of BPNECH • Views of BPNECH (top) and BPNECH01 (bottom) along the b-axis • XPac reveals 2d sheet along these respective axes common to both crystal structures (green) • In BPNECH both highlighted sheets (green & dark green) are identical • In BPNECH01 second sheet highlighted (red) is same sheet structure after a 21 screw operation

  12. Short Contact & Electrostatic Charge Analyses of BPNECH BPNECH01 Atom1 Electrostatic charge 1 Atom2 Electrostatic charge 2 Length Length-VdW • Each molecule in BPNECH01 (top) and BPNECH (bottom) has short contacts w. 8 / 9 neighbours respectively • Short contacts are stronger on the whole than in BAWSAT & BAWSAT01 • ESC & SC data correlate in both polymorphs • Suggests that electrostatic interactions may be significant in formation of both crystal systems O2 -0.434661 H13 :1 0.166816 2.498 -0.222 H13 0.166816 O2 :2 -0.434661 2.498 -0.222 H12 0.203696 O2 :2 -0.434661 2.508 -0.212 O2 -0.434661 H12 :1 0.203696 2.508 -0.212 O2 -0.434661 H1 :3 0.130828 2.596 -0.124 H1 0.130828 O2 :4 -0.434661 2.596 -0.124 O1 -0.447545 H7 :5 0.106818 2.636 -0.084 H7 0.106818 O1 :6 -0.447545 2.636 -0.084 H5 0.093177 Br1 :7 -0.05641 2.987 -0.063 Br1 -0.05641 H5 :8 0.093177 2.987 -0.063 O3 -0.451598 H2 :1 0.12995 2.661 -0.059 H2 0.12995 O3 :2 -0.451598 2.661 -0.059 BPNECH Atom1 Electrostatic charge 1 Atom2 Electrostatic charge 2 Length Length-VdW H1 0.130828 O2 :1 -0.434661 2.394 -0.326 O2 -0.434661 H1 :2 0.130828 2.394 -0.326 O2 -0.434661 H13 :3 0.1308283 2.45 -0.27 H13 0.1308283 O2 :4 -0.434661 2.45 -0.27 H12 0.1308282 O2 :4 -0.434661 2.496 -0.224 O2 -0.434661 H12 :3 0.1308282 2.496 -0.224 H2 0.12995 O3 :4 -0.451598 2.575 -0.145 O3 -0.451598 H2 :3 0.12995 2.575 -0.145 H7 0.106818 O1 :5 -0.447545 2.624 -0.096 O1 -0.447545 H7 :6 0.106818 2.624 -0.096 O1 -0.447545 Br1 :7 -0.05641 3.313 -0.057 Br1 -0.05641 O1 :7 -0.447545 3.313 -0.057 H9 0.06238 O2 :4 -0.434661 2.672 -0.048 O2 -0.434661 H9 :3 0.06238 2.672 -0.048 O3 -0.451598 H3 :8 0.062736 2.691 -0.029 H3 0.062736 O3 :9 -0.451598 2.691 -0.029

  13. Comments I • Several points worth noting: • Overall analysis involves several techniques - hard to draw conclusions using them in isolation • XPac analysis uses ’top-down’ approach - data derived from polymorph crystal structures • Modelling of electrostatic charges is ‘bottom-up’ approach - data derived from molecule • One goal of Comb-e-Chem project - combine data from different analyses to derive novel data & develop it into meaningful knowledge

  14. Comments II • Major ‘bottlenecks’ throughout project have been workflow related: • Data transfer from one application to another • ‘Driving’ applications to obtain the data • Methods of automation investigated: • perl to write data-transfer scripts • Spreadsheets to automate calculations • Ultimate aim of providing complete analysis of electrostatic interactions of a molecule in context of its crystal packing as a single ‘callable’ process

  15. Acknowledgements • Prof. Mike Hursthouse • The Group – Dr. Simon Coles, Dr. Mark Light, Dr. Peter Horton, Dr. Ann Bingham, Dr. Thomas Gelbrich, Dr. Stefan Christensen, Dr. Yang Li, Dr. David Hughes, Suzanna Ward • EPSRC E-Science project (GR/R67729, Comb-e-Chem)

More Related