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Effect of crystal packing

Effect of crystal packing. Packing refers to arrangement of individual molecules in the crystal. The “packing forces” to simply fill the space if no significant intermolecular interactions. Examples of possible intermolecular interactions: Electrostatic interactions in ionic crystals

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Effect of crystal packing

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  1. Effect of crystal packing • Packing refers to arrangement of individual molecules in the crystal. • The “packing forces” to simply fill the space if no significant intermolecular interactions. • Examples of possible intermolecular interactions: • Electrostatic interactions in ionic crystals • Dipole-dipole interactions in salts and polar molecules. • H-bonding(may be considered a sub-type of dipole-dipole interactions) • Closed-shell M-M interactions “metallophilic bonding” • Good understanding of packing may allow us the understanding of what leads to certain interesting physical properties that may be important for a variety of applications.

  2. * Just packing forces even without specific intermolecular forces may lead to various interesting properties when certain crystallographic point or space groups are obtained • We illustrated this last time (piezoelectricity, pyroelectricity, ferroelectricity, optical activity, enantiomorphism, ) * Certain types of intermolecular interactions may lead to other interesting properties.  H-bonding and protein structure, electrostatic stacking and magnets or conductors, metallophilic stacking and luminescent materials, etc. * We shall illustrate some specific cases studies from the literature.

  3. Literature case studies TRIBOLUMINESCENCE: Non-centric space groups Conducting materials Segregated 1-D stacks Magnetic materials Integrated 1-D stacks Photoluminescent materials Packing by closed-shell metal-metal interactions

  4. Case study# 1: TRIBOLUMINESCENCE: DISCUSSED IT LAST TIME: • Related to piezoelectricity. • Non-centric space groups (Zink’s rule). • Exceptions might occur if: • Compound is ionic • Presence of iezoelectric impurities • Papers discussed (responsible for): • B. P. Chandra, J. I. Zink, Inorg. Chem., 1980, 19, 3098. • Cotton, F. A.; Daniels, L. M.; Huang, P. Inorg. Chem. Comm., 2001, 4, 319.

  5. Case study# 2: Conducting materials • Crystal packing: infinite 1-D chains, but segregated stacks: …D-D-D-D-….//…A-A-A-A-…. D= electron donor A= electron acceptor • Electrostatic interactions between the two segregated chains • Conducting materials (Metals)

  6. Case study# 3: Magnets • Crystal packing: infinite 1-D chains with alternating D/A molecules (integrated stacks): …D-A-D-A-D-A-D-A-…. D= electron donor A= electron acceptor • Electrostatic interactions WITHIN the chain  Molecular Magnets (strong ferromagnetic coupling)

  7. Organic example… • TTF-based “Organic Metals” • Donor (D)/Acceptor(A) adducts of TTF with organic acceptors like TCNQ. • TTF = tetrathiafulvalene • TCNQ = 7,7,8,8-tetracyanoquinodimethane • Draw structures

  8. Crystal structure shows segregated stacks (draw structure) • “ORGANIC METALS”!!! * Papers to read: • Shaik, S. S. J. Am. Chem. Soc. 1982, 104, 5328. • Ferraris, J.; Cowan, D. O.; Walatka, V. J.; Perlstein, J. H., J. Am. Chem. Soc. 1973, 95, 948. • Coleman, L. B.; Cohen, M. J.; Sandmand D. J.; Yamagishi, F. G.; Garito, A. F.; Heeger, A. J.*Solid State Commun 1973, 12, 1135. *: Noble Laureate, 2001

  9. Inorganic example… • Dithiolene complexes of d8 metals • [M(SS)2]2+[M’(SS’)2]2- • Stack in two ways: • (1) …D-A-D-A-D-A-D-A-…. • Produce “ion pair charge transfer” (IPCT) absorptions and lead to electrical conductivity (conductors) • (2) …D-D-A-D-D-A-…. • Don’t have IPCT but can be paramagnetic (usually TIP) and semiconducting

  10. Papers to read: • Robertson, N.; Cronin, L. Coord. Chem. Rev. 2002, 227, 93. • Kisch, H.; Eisen, B.; Dinnebier, R.; Shankland, K.; David, W. I. F.; Knoch, F. Chem. Eur. J. 2001, 7, 738. • Kisch, H. Comments Inorg. Chem. 1994, 16, 113. • Bigoli, F.; Deplano, P.; Mercuri, M. L.; Pellinghelli, M. A.; Pilia, L.; Pintus, G.; Serpe, A.; Trogu, E. F. Inorg. Chem. 2002, 41, 5241. • Tanaka, H.; Okano, Y.; Kobayashi, H.; Suzuki, W.; Kobayashi, A. Science 2001, 291, 285. • Coomber, A. T.; Beljonne, D.; Friend, R. H.; Brédas, J. K.; Charlton, A.; Robertson, N.; Underhill, A. E.; Kurmoo, M.; Day, P. Nature 1996, 380, 144.

  11. P 1 R1 = 0.040 { [(dbbpy)Pd(dmid)]2 [TCNQ] } 3.48 3.40 Smucker, B. W.; Hudson, J. M.;Omary, M. A.; Dunbar, K. R. “Structural, Magnetic, and Optoelectronic Properties of Diimine-dithiolato Pt(II) and Pd(II) Complexes and their Charge-Transfer Adducts with Nitrile Acceptors”,Inorg. Chem. 2003, 42, in press.

  12. Stacking in the supramolecular chains of {[(dbbpy)Pt(dmid)]2[TCNQ]} --DDADDADDADDA– infinite stacks

  13. [(dbbpy)Pt(dmid)]2[TCNQ] TIP = 0.0023 emu/mol Magnetic Measurements of [(dbbpy)Pt(dmid)]2[TCNQ] Simple Paramagnet cT (emu cgs K/mol) T (K) Predicted to be Pauli Paramagnetism exhibited by conductors or semiconductors due to unusually large TIP magnitude

  14. Clear SEM images were obtained for crystals that were not coated with a conducting film, suggesting a non-insulator behavior for these solid crystals (conductors or semiconductors).

  15. Case study# 4: Photoluminescent materials • Crystal packing:by virtue of closed-shell metal-metal interactions • e.g., d10 complexes of Au(I), Ag(I), and Cu(I) • D10-d10 bonding is counterintuitive but takes place due to correlation/relativistic/hybridization effects • “Aurophilic; argentophilic; cuprophilic; argentoaurophilic” attractions often lead to photoluminescence

  16. Scheme 1. Versatility of the reported supramolecular structures of Au(RNC)X compounds.

  17. White-Morris, R. L.; Olmstead, M. M.; Balch, A. L.; Elbjeirami, O.; Omary, M. A. “Orange Luminescence and Structural Properties of Three Isostructural Halocyclohexylisonitrilegold(I) Complexes”, Submitted to Inorg. Chem. on February 19, 2003.

  18. The structural organization of (CyNC)AuIBr

  19. Luminescence emission and excitation spectra for single crystals of (CyNC)AuICl, (CyNC)AuIBr, and (CyNC)AuII.

  20. GLOWING Chains Burini; Fackler; Omary, et al. Inorg. Chem.2000, 39, 3158.

  21. LUMINESCENCE THERMOCHROMISM Burini; Fackler; Omary; Staples, et al. Inorg. Chem.2000, 39, 3158.

  22. SUPRAMOLECULAR CHAIN ASSEMBLIES Burini; Fackler; Omary; Staples et al. J. Am. Chem. Soc. 2000, 122, 11264-11265.

  23. [TR(carb)] [TRHg] 2 Intensity, arb. units TR(carb) Average spacing -1 ~ 1420 cm 15 17 19 21 23 25 27 3 -1 Wavenumber/10 cm Luminescence spectraof TR(carb) and [TR(carb)]2[TRHg] in the solid state at 77 K. t = 10ms Raman spectrum of a solution of TR(carb) in CH2Cl2 at RT

  24. Au3(bzim)3.TCNQ, 2:1 stacks Au3(carb)3.C6F6 , 1:1 stacks 3.152 Å 3.152 Å Omary; Fackler; Burini; et al. J. Am. Chem. Soc. 2001,123, 9689-9691.

  25. Emission spectra of TR(carb) versus exposure time to C6F6 vapor at ambient temperature and pressure • Exposure to C6F6VAPOR leads to the quenching of the luminescence of TR(carb)…. • Luminescence re-generated when crystals immersed in non-dissolving solvent.

  26. Photoluminescence properties of Au3(carb)3.octafluoronaphthalene • The bright yellow luminescence is assigned to emission of the organic component. • The emission is strong at ambient temperature in the adduct while the octafluoronaphthalene is luminescent only at cryogenic temperatures. • The structured emission at 77K has a similar profile to that in the organic compound, with a modest red shift. • The Au-based emission is quenched because it is related to a dimer of the Au3 unit while the structure of the adduct does not show this dimerization.

  27. Do acidic trinukes have similar exciting luminescence properties?

  28. Omary; Kassab; Haneline; Elbjeirami; GabbaiInorg. Chem. 2003, 42, 2176-2178.

  29. Luminescence spectra of Hg3.pyrene at RT and 77 K • = 568 ± 8 ms (RT) 423 ± 8 ms (77K) Omary; Kassab; Haneline; Elbjeirami; GabbaiInorg. Chem. 2003, 42, 2176-2178.

  30. Copper and silver trimers…Do you always get what you pay for???

  31. FIGURE 1 lexc=290nm lexc=330nm

  32. FIGURE 2 IR spectrum Raman spectrum 1138 cm-1 1147 cm-1 The indicated vibrational peaks are in good agreement with the vibronic spacing in the emission spectra of Ag1, Cu1, and Cu2. 9

  33. FIGURE 3 lexc=330nm lexc=290nm lexc=325nm

  34. FIGURE 4 lexc=290nm lexc=260nm lexc=265nm

  35. CompoundLifetime (at lmax) Cu1 168 ms Ag1 118 ms Cu2 73 ms Cu3 52 ms Ag2 1.5 ms Ag3 1.0 ms Tunable phosphorescence lifetimes! Example of curve fitting • Ligand based emissions: Nice illustration of the heavy-atom effect!…note the decrease in t on going from Cu1 to the heavier Ag1 and from Cu1 to Cu2. • As the metal contribution increases, the lifetime decreases…. note the decrease in t on going from Ag2Ag3.

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