|Title:||Professor of Chemistry|
B.S., 1965, Hobart College.
Ph.D., Pennsylvania State University.
Postdoctoral Fellow, 1970-71, University of Illinois, Urbana-Champaign
The goal of our research is to design, synthesize and use novel ligand systems that show unusual properties or selectivity toward specific metal ions. Chelate systems based on pendent arm macrocycles, crown ethers and substituted bisphosphonic acids are employed in our work. Potential applications for these ligands include use as reagents for the determination, separation, or immobilization of metal ions. Alkyl-substituted bisphosphonic acids, for example, are effective solvent extraction reagents which are used to prepare extraction chromatographic exchange resins.
Recently, supercritical fluid carbon dioxide modified by the addition of complexing agents has been utilized in the extraction of metal ions from various matrices. It has been observed that the introduction of fluorine- and silicone- substituted groups to the ligands can enhance the efficiencies of extraction using supercritical fluids. Our current research is focused on novel bisphosphonic acid ligands that could be used for supercritical carbon dioxide extraction. Specifically, selected gem-bisphosphonic acids are being rendered carbon dioxide-soluble by the introduction of appropriate "CO2-philic" substituents. Partial esterification of a bisphosphonic acid can enhance its solubility in non-aqueous solvents while leaving the remaining acidic hydrogen atoms available for charge neutralization. Thus, our target ligands are the partial ester derivatives in which silicon- or fluoro- containing groups serve as the ester functionality.
A highly efficient method for selectively forming P,P´-dialkyl partial esters of methylenebisphosphonic acid from the corresponding acid chloride was recently developed. This method uses tetrazole to catalyze the selective coupling of methylenebis(phosphonic dichloride) with two equivalents of alcohol under mild, anhydrous conditions. Preliminary results indicate that the fluoro-containing partial esters and silicone-containing tetraesters that can be formed by the reactions shown in Scheme 1 show enhanced supercritical carbon dioxide solubility. The aggregation, solvent extraction and metal ion complexation chemistry of these "CO2-philic ligands is currently under investigation.
"Alkaline Phosphatase Inhibition by Vanadyl-β-Diketone Complexes: Electron Density Effects", Amanda J. Ziegler, Jan Florián, Miguel A. Ballicora and Albert W. Herlinger, J. Enzy. Inhib. Med. Chem., 24(1), 1-7 (2009).
"Bis[3(trimethylsilyl)propyl] ethylenebisphosphonate, H2DTMSP[EBP]", C. C. McLauchlan, A. J. Ziegler, C. R. Sosnowski and A. W. Herlinger, Acta Crystallographica, C63, 132-134, (2007).
"Metal Extraction by Sulfur-Containing Symmetrically-Substituted Bisphosphonic Acids. Part I. P,P'-Di(2-ethylhexyl) Methylenebisthiophosphonic Acid", P. R. Zalupski, R. Chiarizia, M. P. Jensen and A. W. Herlinger, Solvent Extr. Ion Exch., 24, 331-346 (2006).
"Acid-Base Equilibria and Organic-Water Distribution for Symmetrically Substituted P,P'-Dialkyl Partial Esters of Bisphosphonic Acids", P. R. Zalupski, M. P. Jensen, R. Chiarizia, M. P. Chiarelli and A. W. Herlinger, Solvent Extr. Ion Exch., 24, 177-195 (2006).
"Investigation of Acid-Base Equilibria for Symmetrically Substituted P,P'-Dialkyl Partial Esters of Bisphosphonic Acids", P. R. Zalupski, M. P. Jensen and A. W. Herlinger, J. Solution Chem., 34, 869-880 (2005).
"Application of Molecular Connectivity Indices to the Design of Supercritical Carbon Dioxide-Soluble Metal Ion Extractants: SC-CO2 Solubilities of Symmetrically-Substituted Alkylenediphosphonic Acids", D. R. McAlister, M. L. Dietz, D. C. Stepinski, P. R. Zalupski, J. A. Dzielawa, R. E. Barrans, Jr., J. N. Hess and A. W. Herlinger, Separation Sci. Technol., 39, 761-780 (2004).