Fundamental research in the field of materials chemistry plays a critical role in the discovery and application of new and better performing materials. This is achieved in three steps i) synthesis of novel materials with better properties, ii) study their structural, physical, and chemical characteristics, and 3) investigation of their potential applications. Our research program has strong emphasis on synthesis of new inorganic materials, determination of their crystal structure, and study of their physical and chemical properties. The design of new materials from specific modules is the unifying theme between the main two research projects in our laboratory. For more information on these projects see the following web site: http://www.wfu.edu/~lachgar

Hydrothermal Synthesis of Open-frameworks Metal Phosphates and Arsenates

Some metal phosphates and arsenates exhibit interesting physical and chemical properties that are related to their open-framework structures. The existence of interlayer spaces, interconnected tunnels, and different size cavities give these compounds potential applications as absorbents, catalysts, ion exchangers, solid state electrolytes, and non-linear optical materials. Our research in this field aims at low temperature hydrothermal synthesis of novel metal phosphates and arsenates, and their structural characterization. Three types of compounds, binary indium phosphates (In-PO₄), ternary indium phosphates (A-In-PO₄, A = cation), and mixed indium-transition metal phosphates are investigated. Examples of compounds recently discovered in our group include the layered compound Ca₂In(PO₄)(HPO₄)₂·H₂O, and the 3D framework compound Ba₃In₂(HPO₄)₆.

Synthesis and characterization of cluster-based low-dimensional materials

The aim of this project is to prepare and characterize low-dimensional or open-framework materials containing octahedral metal clusters. The project involves the systematic study of niobium oxychlorides containing octahedral Nb₆L₁₈ (L = Cl, O) clusters to reach a fundamental understanding of the correlation between the cluster configuration and the framework dimensionality. The work's broad benefit is in identifying and understanding the structure determining factors that will ultimately lead to making these materials by design. Our strategy is to use a combination of ligands to make compounds with new structure types, and perhaps interesting magnetic or conductivity properties. This approach has led to the successful synthesis of novel compounds with 3D, 2D, and 1D frameworks. Our studies point to the existence of a wealth of compounds with novel frameworks accessible via solid-state high temperature synthesis.

Two examples of layered cluster-based niobium oxychloride recently made in our laboratory

Publications

1. Ekaterina V. Anokhina, Cynthia S. Day, and Abdessadek Lachgar, “A new quasi-one-dimensional niobium oxychloride cluster compound CS₂Ti₄Nb₆Cl₁₈O₆: Structural effects of ligand combination”, Inorg. Chem. 2001, 40 (20): 5072-5076.
2. Strobele M, Glaser J, Lachgar A, Meyer HJ, “Structure and electrochemical study of Nb₃Cl₈”, Z. Anorg. Allg. Chem. 2001, 627 (8): 2002-2004.
3. Tang XJ, Gentiletti MJ, Morozov VA, Lazoryak BI, Lachgar A, “ The pillared layered framework of Ba₃(In_1-xM_x)₂(HXO₄)₆ (0 ≤ x ≤ 1; M = Fe, Cr; X = P, As): synthesis, crystal structure, thermal stability and Mossbauer spectroscopy”, Solid State Sciences, 2001, 3 (1-2): 143-153.
4. Ekaterina V. Anokhina, Cynthia S. Day, and Abdessadek Lachgar, “A new layered niobium oxochloride cluster compound with novel framework topology", Chem. Comm. 2000, 16 1491-1492
5. Ekaterina V. Anokhina, Michael W. Essig, Cynthia S. Day, and Abdessadek Lachgar “Structural studies of indium and thallium insertion into the framework of the cluster compound Ti₂Nb₆Cl₁₄O₄", Inorg. Chem. 2000, 39: (10) 2185-2188
6. Ekaterina V. Anokhina, Cynthia S. Day, and Abdessadek Lachgar, "Towards the Design of Open-Framework Cluster materials: A New Layered Niobium Oxochloride Related to Hexagonal Bronzes", Angew. Chem. 2000, 39: (6) 1047
7. Ekaterina V. Anokhina, Michael W. Essig, Cynthia S. Day, and Abdessadek Lachgar "Ti₂Nb₆O₁₂: A Novel Niobium Oxide Cluster Compound with "Chevrel Phase" Intercluster Connectivity Type", J. Am. Chem. Soc. 1999, 121, 6827-6833
8. Nagele A, Gibson K, Lachgar A, Meyer HJ “Synthesis, structure, and decomposition of (NH₄)₂[Mo₆Cl₁₄]•H₂O", Z. Anorg Allgem Chem. 1999, 625: (5) 799-802
9. X. Tang, A. Jones, B.J. Gross, J.L. Yarger, and A. Lachgar, “Synthesis, Crystal Structure, NMR Studies, and Thermal Stability of Mixed Iron-Indium Phosphates with Quasi One-dimensional Frameworks" Inorg. Chem., 1999, 38(26), 6032-6038
A. Nägele, E. Anokhina, J. Sitar, H.-J. Meyer, and A. Lachgar "Synthesis and Crystal Structures of ATi[Nb₆Cl₁₈] Compounds (A = K, Rb, Cs, In, Tl), Z. Naturforsch. Accepted, Oct. 1999
11. E.V.Anokhina, M.W.Essig, A.Lachgar, “Ti₂Nb₆Cl₁₄O₄: A Unique 2D-1D Network Combination in Niobium Cluster Chemistry" Angew. Chem. Int. Ed. Engl. 1998, 37, 522-525.