There are 3 main projects in the Starnes research group.

  1. The Development of Synthetic Hosts for Anion Recognition Applications
  2. The Development of Synthetic Hosts for Chiral Recognition Applications
  3. The Development of Molecular Switches

Project 1: The Development of Synthetic Hosts for Anion Recognition Applications.

One aspect of the Starnes research group is centered on the development of synthetic receptors for anions of environmental and biological significance. Environmentally, many anions (such as perchlorate, nitrate, nitrite, sulfate and pertechnetate) present themselves as toxic and problematic contaminants in lakes, rivers, aquifers, nuclear waste repositories etc. We aim to develop sensors and extraction agents for these anions. There are also many anions of biological importance such as DNA, RNA, proteins and peptides. The development of receptors for these analytes has diagnostic applications in the monitoring of cellular processes.

The research utilizes computational software to design the artificial receptor on a computer, analyze its conformational preferences computationally and then evaluate the receptors molecular recognition properties computationally. Receptors showing promise computationally are then synthesized in lab and studied for their anion recognition properties.

Diagram of anion recognition
Sensors and extraction agents are able to recognize specific anions.

Project 2: The Development of Synthetic Hosts for Chiral Recognition Applications.

The research group is working to modify hosts previously prepared in the research group that have been shown to function as stereoselective hosts for chiral guests in order to 1) improve on the selectivity of these types of hosts in their guest binding properties and 2) to learn more about the conformations of the hosts and host-guest complexes which will allow the group to improve on host design. One practical result from the work is that it will lead to a better understanding of biological chemistry. Chiral compounds are important, especially in biological chemistry. For example, one enantiomer of a chiral drug is useful whereas its enantiomer might be toxic or deadly. Many biological substrates and structures are chiral as well (such as proteins and what they act on or the product of an enzyme catalyzed reaction). By understanding chiral recognition better, we can understand biological chemistry better or biological recognition in general better. Understanding the structures of the hosts and their complexes will contribute to a better understanding of the requirements for selective chiral recognition. The research could also impact the design of sensors for chiral species, the development of catalysts for chiral synthesis and the separations industry (for the separation of chiral substances such as enantiomeric molecules, which would greatly impact the pharmaceutical industry since one enantiomeric of a chiral drug might be toxic and therefore must be isolated and removed from the drug mixture).

Project 3: The Development of Molecular Switches.

A molecular switch is a molecule or set of molecules that will undergo a pre-defined shift between two or more distinct states in response to a specific stimuli. A schematic illustrating the basic concept is below. There is interest in the development of molecular switches for a variety of applications such as in nanotechnology for application in molecular computers (the different states can represent the binary numerical system 0 and 1).

For this project, we will develop synthetic host compounds that contain a mechanism for a switching stimuli that arises from the stereochemistry (3D shape) of a guest which binds to the host. Depending on the absolute stereochemistry of the guest, the host will exist in one of two different conformations; if the host can exist in conformer A and conformer B, when one enantiomer of a guest binds to the porphyrin host, the host will adopt conformer A. When the opposite enantiomer of a guest binds to the host, the host will adopt conformer B. We aim to utilize 19F-NMR, Circular Dichroism (CD), and fluorescence spectroscopy to determine which conformer the host exists in (and hence determine which stereoisomer of guest is bound). If successful, we will be able to determine the absolute stereochemistry of a guest or the stereo composition of a mixture of enantiomers from the 19F-NMR, CD or fluorescence response. This will represent a major advance is chiral discrimination using spectroscopic methods. The knowledge gained from this study will contribute to a better understanding of the requirements for selective chiral recognition. This type of system could find use in the pharmaceutical industry for example for high-throughput enantiopurity determination of chiral pharmaceutical agents.

Diagram showing relationship between guest and host compounds
The stereochemistry of a guest determines the conformation of its host.

A student working on any of these projects will be trained in synthetic organic chemistry, including the synthesis, isolation, purification and identification of organic compounds. The student will use techniques such as computational chemistry, NMR, IR, circular dichroism, fluorescence and mass spectrometry to study the systems.

Contributing Faculty and Staff

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