John D. Lamb
1971 B.S. Chemistry, Brigham Young University; University Scholar; graduated "with high honors"
1978 Ph.D. Inorganic Physical Chemistry, Brigham Young University
Research interests include:
- Macrocyclic chemistry,
- Ion chromatography, and
- Liquid membranes
Our research involves the design and synthesis of novel macrocyclic compounds and their inclusion in separation systems such as ion chromatography and liquid membranes. We focus primarily on the separation of ions, both cations and anions, in aqueous solution. We have focused our most recent work on a class of macrocycles called resorcinarenes which can be substituted on the upper rim with secondary ligand structures such as cyclen units for interesting ion selectivities.
The common theme running through all the research projects in our group is separations of chemical species, both for analytical and preparative purposes. Most of our projects take advantage of the unusual selectivities of chemical binding by macrocyclic ligands, such crown ethers, calixarenes, and resorcinarenes. Currently, the projects can be grouped into the following categories:
(1) Macrocycle-Based Ion Chromatography. These projects combine the unusual selectivities of macrocyclic ligands with the separation efficiencies of ion chromatography. Anion exchange and cation exchange columns can be formed by the adsorption or bonding of macrocyclic ligands to reversed phase columns. Capacity gradient separations of anions are achieved by changing the eluent cation from one with high macrocycle affinity to one with low macrocycle affinity during the course of the separation. Capacity gradients exhibit excellent separation characteristics coupled with better baseline stability than conventional gradient systems. Gradient separations of both anions and cations are also possible by changing column temperature during the course of the separation. These kinds of columns have now reached the commercialization phase. The variety of macrocyclic ligands, substrates, and separation conditions offers a wide potential for novel research.
(2) Macrocycle-Based Membrane Separations. These projects involve the synthesis, characterization, and application of new macrocyclic ligands to the separation of metal cations and anions. New ligands are synthesized and subsequently characterized in our laboratory through various methods, including the determination of K, ΔH, and ΔS for macrocycle-ion interaction by calorimetry. The ligands are evaluated for their applicability to cation separations by solvent extraction or by liquid membranes. Recently we have focused our attention on the separation of anions from nuclear waste.
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