Inorganic and Solid State Chemistry
Brian H. Ward
Assistant Professor
(256) 824 - 6365
Email: bward@chemistry.uah.edu	Homepage: The Ward Group
Biographical Information
Brian Ward was born and raised in Orlando, FL. He graduated from Florida State University with a B. S. in chemistry in 1992, and he returned to the chemistry department as adjunct faculty in 2001. Dr. Ward received his Ph.D. in inorganic chemistry from the University of Florida in 1997. As a member of Professor Daniel R. Talham’s research lab, he was involved in the development of novel inorganic and organic solid-state materials with interesting electrical and magnetic properties. After leaving UF, Dr. Ward conducted postdoctoral research at Argonne National Laboratory in the molecular materials group where his work included design, synthesis, crystallization and characterization of molecular based solids with novel electronic or magnetic properties.  After two years at ANL, Dr. Ward went back to Tallahassee, FL where he was a postdoctoral associate in Professor James S. Brooks’ research group at the National High Magnetic Field Laboratory.  Here he investigated the role anisotropy in the electronic and magnetic properties of molecular crystals.  In the fall of 2004, Dr. Ward joined the UAH chemistry department as an assistant professor.
Research Interests
The fabrication of novel magnetic and electronic nanomaterials is imperative. The miniaturization of electronic devices is advancing at a rapid pace, but current technologies will need to be replaced as the dimensions approach those of molecules, or rather the nanoscale. Chemists have recognized that controlling matter at the nanometer scale can be used to make new materials with unique and, potentially, commercially useful properties. Before molecular devices can be built and tested, chemists need to synthesize the molecules that drive them. Solid-state chemistry and materials chemistry will have an integral role in the discovery of new materials with novel structures, magnetic, and conducting properties. Our research efforts are aimed at the synthesis of molecule-based inorganic and organic solid-state compounds for systematic structure-property correlation studies to investigate the nature of unusual magnetic, optical, and conducting phenomena. These research efforts can be classified into three areas.
Low-Dimensional Inorganic Coordination Polymers
Solid-state chemistry relies heavily on the relationship between a compound’s crystal structure and physical properties. The interplay between experiment and theory is the motivational factor, which stimulates the quest for new materials. Many inorganic coordination compounds have been synthesized and their physical properties (i.e. electrical, magnetic, and structural) compared and contrasted to the theoretical models. These materials range from conducting solids to magnetic insulators. Specifically, low-dimensional molecule-based inorganic magnetic insulators provide a veritable bonanza of effects that can be studied. Low-dimensional inorganic coordination polymers have received considerable attention lately, because several examples of ferromagnets have resulted. These magnetic systems display a variety of unique solid-state structures; for example, 1D chains, zigzag chains, and 2D ladders. Our goal is to synthetically explore these systems using transition metal and lanthanide-metal ions with interesting organic bridging ligands, followed by investigation of the crystal structures of the compounds, and studies on their magnetic and optical properties.
Conducting Organic Cation-Radical Salts Incorporating Magnetic Anions
Electrical conduction spans over 24 orders of magnitude, from metals like Cu and Au with conductivities of 105 to 106 Ω-1cm-1, to semiconductors such as GaAs and Si with conductivities of 10-3 to 102 Ω-1cm-1, and electrical insulators such as Teflon and sulfur with room temperature conductivities of 10-9 to 10-18 Ω-1cm-1.  There is a class of materials referred to as organic conductors, which may seem contradictory, because most pure organic materials are electrical insulators with room temperature conductivities of 10-10 Ω-1cm-1.  However, by executing specific chemical reaction sequences using this class of compounds, electrically conducting materials can be made.  Some organic conductors can have conductivity values that rival those of copper and gold.  A subset of organic conductors is the organic superconductors, which are cation-radical salts composed of an organic p-electron donor cations combined with a charge-compensating anions.  The most common route to pure crystalline samples of conducting cation-radical salts is through electrochemical oxidation of the donor in the presence of an appropriate counterion.  Single crystal molecule-based conductors can be used to gather many types of data from a variety of physical measurement techniques.  For example, single crystal X-ray structure determination, 4-point resistivity, DC and AC magnetic susceptibility, EPR, heat capacity, optical reflectance, and Raman spectroscopy measurements can all be performed.  The most fruitful class of organic superconductors is the BEDT-TTF or ET, bis(ethylenedithiotetrathiafulvalene) class of conductors.  The X-ray crystal structures of BEDT-TTF conductors and superconductors show the layered nature of the materials.  To date, the BEDT-TTF family of cation-radical molecular solids has resulted in over 50 superconductors, which is the largest number for any of the organic cation-radical salt families.  Recently a class of BEDT-TTF salts has been synthesized containing organic counterions of the type SF5XSO3, where X = CH2CF2, CHFCF2, CH2, CHF, and CF2.  The salt β’’-(BEDT-TTF)2SF5CH2CF2SO3 is the first purely organic superconductor, with Tc = 5 K.  The crystal structure β’’-(BEDT-TTF)2SF5CH2CF2SO3 is shown in the figure below.  The structure contains conducting layers of BEDT-TTF radical cations alternating with SF5CH2CF2SO3- anion layers.  The β’’ refers to the packing motif adopted by the BEDT-TTF donor molecules.  The solid lines between BEDT-TTF cations point out short intermolecular contacts representative of the orbital overlaps responsible for the delocalization of the valence electrons into a conduction band.  Most of these contacts are primarily between molecules located on adjacent stacks, forming 2D sheets of BEDT-TTF radical cations.
Our goal is to prepare new examples of conducting organic cation-radical salts with inorganic magnetic counterions. The aim here is to combine electrical conduction with magnetism in a molecule-based material to obtain long-range magnetic coupling between isolated localized spins on the inorganic anions through the mobile p-electrons of the organic networks. Also, it would be interesting to see if the superconducting state is destroyed by an antiferromagnetic-to-ferromagnetic transition in the inorganic anion layer.
Bi-functional Hybrid Organic/Inorganic Materials
One of the current challenges in solid-state chemistry is the search for molecule-based materials which are multi-functional. Great interest is currently devoted to obtain organic/inorganic hybrid materials which combine the electrical conducting properties of the organosulfur donors with the magnetic effects of transition-metal ions. It is expected that there is long-range magnetic coupling between the localized spins on d-orbitals of the paramagnetic transition metal ions of the inorganic part through the mobile electrons of the organic conducting networks (p-electrons). Our strategy involves the synthesis of TTF derivatives which have metal-ion binding groups covalently attached at the periphery. Combination with appropriate metal ions would lead to complexes with multiple physical properties such as electrical conductivity or superconductivity, coupled with optical and magnetic properties.
Selected Publications
E. Cizmar, J.-H. Park, S.J. Gamble, B.H. Ward, D.R. Talham, J. van Tol, L.-C. Brunel, M. Orendac, A. Feher, J. Sebek, and M.W. Meisel “Experimental Study of [MnCl3(C12H8N2)]n: An S = 2 Heisenberg Antiferromagnetic Chain” Journal of Magnetism and Magnetic Materials, 2004, 272, 874-875. [PDF] I.B. Rutel, S.A. Zvyagin, J.S. Brooks, J. Krzystek, P. Kuhns, A.P. Reyes, E. Jobiliong, B.H. Ward, J.A. Schlueter, R.W. Winter, and G.L. Gard “High-Field Magnetic Resonant Properties of β’-(ET)2SF5 CF2SO3” Physical Review B, 2003, 67, 214417. [PDF]  J.A. Schlueter, U. Geiser, H.H. Wang, A.M. Kini, B.H. Ward, J.P. Parakka, R.G. Dougherty, M.E. Kelly, P.G. Nixon, G.L. Gard, L.K. Montgomery, H. -J. Koo, and M. -H. Whangbo “Trifluoromethylsulfonyl-Based Salts of BEDT-TTF: Crystal and Electronic Structures and Physical Properties” Journal of Solid State Chemistry, 2002, 168, 524-534. [PDF]  O Fuentes, H.H. Wang, B.H. Ward, J.H. Zhang, D.M. Proserpio, F. Calvagna, C.E. Check, K.C. Lobring, and C. Zheng “Synthesis, Structural Analysis, and Superconductivity of BaxV6S8” Chemistry of Materials, 2001, 13(9), 3051-3056. [PDF]  J.A. Schlueter, B.H. Ward, U. Geiser, H.H. Wang, E. Morales, P.G. Nixon, R.W. Winter, G.L. Gard, H. -J. Koo, and M. -H. Whangbo “Crystal Structure, Physical Properties, and Electronic Structure of a New Organic Conductor β''-(BEDT-TTF)2SF5CHFCF2SO3” Journal of Materials Chemistry, 2001, 11(8), 2008-2013. [PDF]  B.H. Ward, I.B. Rutel, J.S. Brooks, J.A. Schlueter, R.W. Winter, and G.L. Gard “Millimeter-Wave Spectroscopy of the Organic spin-Peierls System β’-(ET)2SF5 CF2SO3” The Journal of Physical Chemistry B, 2001, 105(9) 1750-1755. [PDF]  B.H. Ward, J.A. Schlueter, U. Geiser, H.H. Wang, E. Morales, J.P. Parakka, S.Y. Thomas, J.M. Williams, P.G. Nixon, R.W. Winter, G.L. Gard, H. -J. Koo, and M. -H. Whangbo “Comparison of the Crystal and Electronic Structures of Three 2:1 Salts of the Organic Donor Molecule BEDT-TTF with Pentafluorothiomethylsulfonate Anions SF5CH2SO3¯, SF5CHFSO3¯, and SF5CF2SO3¯” Chemistry of Materials, 2000, 12(2), 343-351. [PDF]  B.H. Ward, G.E. Granroth, J.B. Walden, K.A. Abboud, M.W. Meisel, P.G. Rasmussen, and D.R. Talham “Synthesis, Structure, and Physical Properties of a New Organic Metal, (BEDO-TTF)4[C4N6]·H2O” Journal of Materials Chemistry, 1998, 8(6), 1373-1378. [PDF]  B.H. Ward, G.E. Granroth, K.A. Abboud, M.W. Meisel, and D.R. Talham “New BEDT-TTF Salts Incorporating the Hydrogen Dichloride (HCl2¯) Anion” Chemistry of Materials, 1998, 10(4), 1102-1108. [PDF] B.H. Ward, G.E. Granroth, D.R. Talham, and M.W. Meisel “Magnetic Properties of the Antiferromagnetic S = 1 Spin Chain System [Ni(C4H12N2)2(µ-N3)]n(ClO4)n” Journal of Magnetism and Magnetic Materials, 1998, 177-181, 661-662. [PDF]
Department of Chemistry College of Science University of Alabama in Huntsville