My research is focused on the understanding of intermolecular effects in ordered media. In particular we are investigating the effect different media impart upon chemical reactivity with the goal of designing organic systems with specific functional control.
Self-Assembled Monolayers
The first research area is designing monolayers with specific intermolecular interactions within the monolayer structure. We are studying monolayers grown on transparent glass surfaces because we are initially probing the intermolecular interactions on the surface through optical studies of a photochromic spiropyran that is attached. Upon ultraviolet irradiation this spiropyran converts into a photomerocyanine structure with an absorbance in the visible region. This chromophore can be detected and the decay rate of the photomerocyanine to the spiropyran form in the dark is directly related to the specific intermolecular interactions within the monolayer.
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| Two component SAM is synthesized and attached to transparent glass surface | Upon photolysis of slide the photomerocyanine absorbance is observed, and the decay rate of the photomerocyanine in dark is dependent upon the interactions within the monolayer |
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The photochromic SAM slide is placed in light path of photodiode array UV-Vis machine. The slide can be photolyzed in air as shown or immersed in appropriate solvent. |
Photochromic Sensors and Switches
A second research area is studying the effect of "hard" and "soft" cages upon the stability of included organic compounds. Once again organic photochromic materials are used to probe these effects by studying the photogeneration and lifetime of the photogenerated species within the caged environment compared to fluid studies. The type of cages employed are host/guest single crystals like cyclodextrins (hard cages) which form channel inclusion voids where appropriately sized guests may reside and organogels (soft cages) where guests can be included within the optically clear viscoelastic environment where fluid flow has been prevented. Each system offers different types of intermolecular stabilization interactions which can increase the lifetime of the photogenerated photomerocyanines.
| Bromo Substituted Spiropyran Included in gamma-CD Host |  |
Synthesis of Carbon Nanotubes of One Type
In collaboration with the NanoTech Institute at UTD we are attempting to prepare single walled carbon nanotubes through an organic synthesis approach. Instead of trying to purify a mixture of carbon nanotubes produced by current methods, we are attempting to prepare one type of carbon nanotube. Our approach is to prepare carbon rings with diacetylene groups at specified positions. In the solid-state these rings will pack to allow a topochemical polymerization of the diactylene units. This reaction will produce a tubular carbon framework of a certain dimension. Thermal annealing will then be applied with appropriate catalysts to remove remaining hydrogen and form the single walled carbon nanotube.