Self-Assebling Propargylic Alcohols
The project involves the preparation of a series of chiral propargylic alcohols with one fluorinated and one non-fluorinated aromatic ring (1-3 step synthesis), and colloidal study in various environments. This is done in an effort to make supramolecular fibers – colloidal structures with a very high aspect ratio. We have analyzed the gelation ability of a series racemates and one homochiral derivative; all of the racemates form gels in alkane solvents and/or silicone oil. We have studied the thermal stability of successfully prepared gels using differential scanning calorimetry (DSC) and the ball-drop technique. Furthermore, we have done a detailed structural study of the parent gelator utilizing techniques including scanning electron microscopy (SEM), light microscopy, powder X-ray diffraction (XRD), and attenuated total reflectance infrared (ATR-IR) spectroscopy, from which we have developed a molecular-level model for gelation. This work is detailed in our recently published paper in the ACS journal Langmuir. This project represents a collaborative effort between our lab and the labs of Dr. Michal Sabat and Dr. Lin Pu at the University of Virginia (Department of Chemistry).
Biscationic Bicephalic (Double-Headed) Amphiphiles
An amphiphile is a compound possessing a polar, water-soluble group attached to a water-insoluble group. The introduction of amphiphilic molecules to water or organic solvents can result in the formation of a variety interesting aggregates (or association colloids). This general phenomenon has been utilized for a great variety of applications in fields ranging from industry (detergents, thickeners) to medicine (drug delivery, controlled release). The morphology of these aggregates is dependent on and often highly sensitive to the structure of the individual amphiphiles. In this project, we have prepared a series of novel amphiphilic molecules, each containing a two cationic head groups and a hydrophobic unit, connected via a rigid spacer. We study the self-assembly of these new molecules using a range of techniques including conductivity, surface tensiometry and nuclear magnetic resonance (NMR) spectroscopy. Currently, we have teamed up with the Minbiole (JMU Chemistry a Biochemistry) and Seifert (JMU Biology) groups to study the antimicrobial properties of these compounds. This project is funded by the Research Corporation for Scientific Advancement.
Chemical Demonstration Development
The chemistry student organizations at JMU [the Student Affiliates of the American Chemical Society and Alpha Chi Sigma (the professional chemistry fraternity)] have a long-standing tradition of outreach projects to local and regional schools. Both of these organizations regularly provide chemical demonstration presentations for K-12 students and others. Since the Spring semester of 2010, we have expanded and improved upon these foundations for both classroom and outreach activities.
Click here to learn more about our outreach activities. [ChemDemo website!]
Development of Novel Colloid Chemistry Labs
We have successfully developed a series of teaching labs that have subsequently been integrated into several courses at JMU (221L, 346L, 438L and 440P). The labs involve the synthesis and colloidal examination of gemini (“twin”) surfactants, utilizing techniques including organic synthesis, purification, conductivity, fluorescence, surface tensiometry, and DOSY NMR. Recent work has focused on the preparation and study of gemini surfactants with chiral counterions, including NMR and SEM studies. Students in the next iteration of CHEM 440P (Science of the Small – An Introduction to the Nanoworld) will perform these modified experiments. This work is sponsored by the National Science Foundation (Nanoscience in Undergraduate Education award).
Catenanes are molecules with two or more interlocked rings that cannot be separated without breaking a covalent bond. This project lies at the intersection of colloid chemistry (described above) and catenane chemistry. Catenation will introduce novel dynamic processes at the interfacial region of aggregates formed by such molecules. These processes, namely rocking, rattling and rotation of the macrocycles within each other may give rise to unique and interesting colloidal properties. This work is sponsored by the American Chemical Society - Petroleum Research Fund.
Molecular scaffolds are molecules that provide multiple functional groups that act as points of attachment to a variety of groups or biologically significant moieties. A rigid scaffold can serve as a molecular core that holds its substituents in defined orientations in space. The relative positioning of these substituents can have a profound effect on the aggregation, self-assembly, binding ability, and other characteristics of these molecules. Functionalized scaffolds have been widely utilized towards a diversity of ends. We are in the process of synthesizing two stereoisomeric scaffolds which will hold substitutents in defined three-dimensional positions. Once the synthesis has been accomplished and the target scaffolds have been prepared, they will be functionalized to a variety of ends. Firstly, derivatives bearing small peptides may be utilized as enzyme mimics. The enforced juxtaposition of amino acid chains provides a potential binding pocket that mimics the active site of an enzyme. Variation of the order and identity of the amino acids will allow these molecules to be fine-tuned for various substrates. Alternatively, these novel scaffolds will be used to prepare novel gemini surfactants by attachment of amphiphilic moieties. Gemini surfactants contain multiple polar head groups (covalently attached) and multiple non-polar tails. Interest and research concerning geminis has exploded in recent years, both in academia and industry. This is, in part, due to their anomalous characteristics among surfactants including extraordinarily high surface activity and remarkably low critical micelle concentrations (CMC). This is a collaborative project with Dr. Kevin P. C. Minbiole. This work is sponsored by Research Corporation.
To see which students are working on each of these projects, click on our group members page.
Caran group homepage