Professor Brock's research interests center on the structures and properties of molecular crystals. She is particularly interested in the systematics of packing in molecular crystals, and in the design, synthesis, and characterization of solid-state molecular complexes.

Systematics of Crystal Packing

Two types of questions are being investigated. First, to what extent does molecular recognition break down during crystal growth? How often are impurities incorporated into growing crystals? How often are solid solutions formed? We are studying this question by characterizing the crystals precipitated from solutions containing two similar solutes, e.g., two different para-substituted benzoic acids or two different members of the series C6(CH3)nCl6-n. The crystals may be formed exclusively of one solute or the other, the crystals may be solid solutions, or a solid-state compound may be formed. Second, we are using the Cambridge Structural Database to answer more general questions about crystal packing; e.g., how often is the symmetry of a molecule maintained in its crystals? If a molecule has a six-fold rotation axis in solution, what is the chance that its crystals are hexagonal?

Phase Relationships: Polymorphs and Solid-State Molecular Complexes

We are combining information from single-crystal and powder diffraction studies with the results of thermal measurements to construct schematic phase diagrams for molecular crystals. While studying trans-1,2-cyclohexanediol (CHD) in this way we discovered an unusual layered compound of the diol with triphenylphosphine oxide (TPPO).

• M. A. Siegler, Y. Fu, G. H. Simpson, D. P. King, S. Parkin & C. P. Brock, "An Unexpected Co-Crystal with a Variable Degree of Order: 1:1 rac-1,2-Cyclohexanediol/Triphenylphosphine Oxide", Acta Cryst., 2007, B63, 912-925. (view pdf)
• M. A. Lloyd, G. E. Patterson, G. H. Simpson, L. L. Duncan, D. P. King, Y. Fu, B. O. Patrick, S. Parkin & C. P. Brock, "Solid-State Compounds of Stereoisomers: cis and trans Isomers of 1,2-Cyclohexanediol and 2,3-Tetralindiol", Acta Cryst., 2007, B63, 433-447. (view pdf)
• B. O. Patrick & C. P. Brock, "S,S-1,2-Dicyclohexylethane-1,2-diol and Its Racemic Compound: A Striking Exception to Wallach's Rule", Acta Cryst., 2006, B62, 488-497. (view pdf)
• X. Hao, S. Parkin & C. P. Brock, "The Unusual Phases of Anhydrous and Hydrated Pinacol", Acta Cryst., 2005, B61, 689-699. (view pdf)
• X. Hao, M. A. Siegler, S. Parkin & C. P. Brock, "[M(H₂O)₂(15-crown-5)](NO₃)₂: A System Rich in Polymorphs and Modulated Phases", Cryst. Growth Des., 2005, 5, 2225-2232.
• X. Hao, S. Parkin & C. P. Brock, "Three Modulation Patterns in Four Related [M(15-crown-5)(H₂O)₂](NO₃)₂ Structures", ", Acta Cryst., 2005, B61, 675-688. (view pdf)
• X. Hao, J. Chen, A. Cammers, S. Parkin & C. P. Brock, "A Helical Structure with Z'=10", Acta Cryst., 2005, B61, 218-226. (view pdf)
• H.-J. Lehmler, S. Parkin & C. P. Brock, "Packing Conflicts in the Z'=5 Structure of CF₃(CF₂)₃(CH₂)₁₀COOH", Acta Cryst., 2004, B60, 325-332. (view pdf)
• S. Parkin, X. Hao & C. P. Brock, "2-Biphenylol Revisited", Acta Cryst., 2004, B60, 197-203. (view pdf)
• S. A. Bajue, C. Lewis, K. Clarke, F. B. Bramwell, B. O. Patrick & C. P. Brock, "Isostructural or Not? Adducts of Some Aryltin Halides with E-1,2-Bis(4-pyridyl)ethene", Acta Cryst., 2003, C59, m207-m211. (view pdf)
• A. F. Kiely, M. S. Meier, B. O. Patrick, J. P. Selegue & C. P. Brock, "7,8-(Dichloromethano)homo[70]fullerene, an Unusual, but Unexceptional, Methanoannulene", Helv. Chim. Acta, 2003, 1140-1151.
• C. P. Brock, "Crystal Packing in vicinal Diols C_nH_m(OH)₂", Acta Cryst., 2002, B58, 1025-1031. (view pdf)
• C. P. Brock, "Phase Transitions During Crystal Growth?" Mol. Cryst. Liq. Cryst., 2002, 79-85.
• C. P. Brock, "Personal Opinion on the Past, Present and Future of Crystallography", Zeit. Krist., 2002, 217, 286. (view pdf)
• L. L. Duncan, B. O. Patrick & C. P. Brock, "Two Phases of C₉H₁₂O₄: Why Is the Structure at 295 K So Complicated?", Acta Cryst., 2002, B58, 502-511. (view pdf)
• H.-J. Lehmler, L. W. Robertson, S. Parkin & C. P. Brock, "Z'=4 Structure without Obvious Pseudosymmetry: Implications for the Formation of Solid-State Compounds", Acta Cryst., 2002, B58, 140-147. (view pdf)
• P. A. Koutentis, R. C. Haddon, R. T. Oakley, A. W Cordes & C. P. Brock, "Perchlorophenalenyl Radical, C₁₃Cl₉: A Modulated Structure with Nine Threefold-Symmetric Molecules in the Asymmetric Unit", Acta Cryst., 2001, B57, 680-691. (view pdf)
• A. Xia, J. P. Selegue, A. Carrillo, B. O. Patrick, S. Parkin & C. P. Brock, "Two Fluoradene Derivatives: Pseudosymmetry, Eccentric Ellipsoids, and a Phase Transition", Acta Cryst., 2001, B57, 507-516. (view pdf)
• P. A. Koutentis, Y. Chen, Y. Cao, T. P. Best, M. E. Itkis, L. Beer, R. T. Oakley, A. W. Cordes, C. P. Brock, and R. C. Haddon, "Perchlorophenalenyl Radical, J. Am. Chem. Soc., 2001, 123, 3864-3871.
• Xia, A.; Selegue, J. P.; Carrillo, A.; Brock, C. P. "Stereochemical Inversion of a Coordinated, Curved Hydrocarbon: Syntheses and Structures of exo- and endo-[Ru(h⁶-fluoradene)(h⁵-C₅Me₅)][CF₃SO₃]", J. Am. Chem. Soc. 2000, 122, 3973-3974.
• Brock, C. P. "Systematic Study of Crystal Packing"; Howard, J. A. K.; Allen, F. H.; Shields, G. P., Ed.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 1999; Vol. 360, pp 251-262.
• Kiely, A. F.; Haddon, R. C.; Meier, M. S.; Selegue, J. P.; Brock, C. P.; Patrick, B. O.; Wang, G.-W.; Chen, Y. "The First Structurally Characterized Homofullerene (Fulleroid)", J. Am. Chem. Soc. 1999, 121, 7971-7972.
• Fu, Y.; Brock, C. P. "Temperature Dependence of the Rigid-Body Motion of Anthraquinone", Acta Cryst. 1998, B54, 308-315.
• Lloyd, M. A.; Patterson, G. E.; Brock, C. P. "(S,S)-trans-2,3-Tetralindiol", Acta Cryst. 1998, C54, 1486-1488.
• Meier, M. S.; Wang, G.-W.; Haddon, R. C.; Brock, C. P.; Lloyd, M. A.; Selegue, J. P. "Benzyne Adds Across a Closed 5-6 Ring Fusion in C₇₀: Evidence for Bond Delocalization in Fullerenes", J. Am. Chem. Soc. 1998, 120, 2337-2342.
• Brock, C. P.; Fu, Y. "Rigid-Body Disorder Models for the High-Temperature Phase of Ferrocene", Acta Cryst. 1997, B53, 928-938.
• Lloyd, M. A.; Brock, C. P. "Retention of 4-bar Symmetry in Compounds Containing MAr₄ Molecules and Ions", Acta Cryst. 1997, B53, 780-786.
• Lloyd, M. A.; Brock, C. P. "[MPh₄][BPh₄], M = P, As and Sb", Acta Cryst. 1997, B53, 773-779.
• Brock, C. P.; Fu, Y. "Pentachlorotoluene: Rotational and Compositional Disorder", Acta Cryst. 1997, B53, 613-619.
• Brock, C. P.; DeLaLuz, P. J.; Golinski, M.; Lloyd, M. A.; Vanaman, T. C.; Watt, D. S. "Planarity of Nitro-Substituted Phenothiazines", Acta Cryst. 1996, B52, 713-719.
• Brock, C. P. "Investigations of the Systematics of Crystal Packing Using the Cambridge Structural Database", J. Res. Natl. Inst. Stand. Technol. 1996, 101, 321-325.
• Brock, C. P.; Dunitz, J. D. "Towards a Grammar of Crystal Packing", Chem. Mater. 1994, 6, 1118-1127.
• Brock, C. P.; Duncan, L. L. "Anomalous Space-Group Frequencies for Monoalcohols C_nH_mOH", Chem. Mater. 1994, 6, 1307-1312.
• Brock, C. P.; Stoilov, I.; Watt, D. S. "A Steroid Derivative that Crystallizes with Three Molecules in the Asymmetric Unit", Acta Cryst. 1994, C50, 434-438.
• Brock, C. P.; Dunitz, J. D. "On the Prevalence of Polar and Chiral Space Groups", Mol. Cryst. Liq. Cryst. 1994, 242, 329-337.
• Brock, C. P.; Kwiatkowski, S.; Watt, D. S.; Sayed, A. "Two Closely Related Structures: (-)-(7aS)-2,3,7,7a-Tetrahydro-7a-phenylthio-1H-indene-1,5(6H)-dione and Its Racemic Compound", Acta Cryst. 1992, B48, 719-725.
• Brock, C. P.; Dunitz, J. D. "Space-Group Frequencies", Acta Cryst. 1991, A47, 854.
• Brock, C. P.; Schweizer, W. B.; Dunitz, J. D. "On the Validity of Wallach's Rule: On the Density and Stability of Racemic Crystals Compared with Their Chiral Counterparts", J. Am. Chem. Soc. 1991, 113, 9811-9820.
• Brock, C. P.; Dunitz, J. D.; Hirshfeld, F. L. "Transferability of Deformation Densities Among Related Molecules: Atomic Multipole Parameters from Perylene for Improved Estimation of Molecular Vibrations in Naphthalene and Anthracene", Acta Cryst. 1991, B47, 789-797.
• Brock, C. P.; Dunitz, J. D. "Temperature Dependence of Thermal Motion in Crystalline Anthracene", Acta Cryst. 1990, B46, 795-806.
• Brock, C. P.; Minton, R. P. "Systematic Effects of Crystal-Packing Forces: Biphenyl Fragments with Hydrogen Atoms in All Four Ortho Positions", J. Am. Chem. Soc. 1989, 111, 4586-4593.
• Brock, C. P.; Morelan, G. L. "Relationships Between Molecular Geometry, Crystal Packing, and Thermal Motion: Temperature-Dependent Studies of Three Crystal Forms of 4-Hydroxybiphenyl", J. Phys. Chem. 1986, 90, 5631-5640.
• Brock, C. P.; Schweizer, W. B.; Dunitz, J. D. "Internal Molecular Motion of Triphenylphosphine Oxide: Analysis of Atomic Displacement Parameters for Orthorhombic and Monoclinic Crystal Modifications at 100 and 150 K", J. Am. Chem. Soc. 1985, 107, 6964-6970.
• Brock, C. P.; Haller, K. L. "Redetermination of the Structure of the 3:1 Complex of 4,4'-Dinitrobiphenyl with 4-Hydroxybiphenyl, 3C₁₂H₈N₂O₄/C₁₂H₁₀O: Crystal Packing, Molecular Geometry and Thermal Motion", Acta Cryst. 1984, C40, 1387-1390.
• Brock, C. P.; Huckaby, J. L.; Attig, T. G. "Effect of Crystal Packing on Linkage Isomerism in the [Palladium(1,1,7,7-tetraethyldiethylenetriamine)(thiocyanato)]⁺ Cation: Structures of the Hexafluorophosphate Salt and of Four Crystal Forms of the Tetraphenylborate Salt", Acta Cryst. 1984, B40, 595-606.
• Brock, C. P.; Blackburn, J. R.; Haller, K. L. "Structure of 4-Biphenylcarboxylic acid, C₁₃H₁₀O₂: Comparison of the TLS Tensors Derived from Independent-Atom and Rigid-Group Refinements", Acta Cryst. 1984, B40, 493-498.
• Brock, C. P.; Haller, K. L. "Two Crystal Modifications of 4-Hydroxybiphenyl: The Biphenyl Structure Without an Inversion Center and a Fully Ordered Structure Containing Nearly Planar Molecules", J. Phys. Chem. 1984, 88, 3570-3574.
• Brock, C. P.; Dunitz, J. D. "Temperature Dependence of Thermal Motion in Crystalline Naphthalene", Acta Cryst. 1982, B38, 2218-2228.
• Brock, C. P.; Attig, T. G. "Influence of Crystal Packing on the h¹®h³ Rearrangement of an Allyl Ligand. Solution and Solid-State Structures of the Tetraphenylborate and Hexafluorophosphate Salts of a Platinum Allyl Cation", J. Am. Chem. Soc. 1980, 102, 1319-1326.