With support from the Organic and Macromolecular Chemistry Program in the Chemistry Division at the National Science Foundation, Professor V. Ramamurthy of the University of Miami will focus on the supramolecular photochemistry of a special class of supermolecules namely guest@host complexes. In the context of excited state chemistry, of the various organic hosts thus far examined, the octa acid (OA), a synthetic cavitand host, which forms a capsular structure that shields the hydrophobic guest organic molecule from the aqueous exterior, shows considerable potential. To establish OA as a useful reaction medium, the PI proposes to carry out experiments that seek answers to questions on the following topics: (a) Features controlling the stoichiometry of guest-to-OA complexes in water, (b) The dynamics of the OA capsule, (c) Controlled opening of the capsule, (d) The intra-capsular dynamics of the guest molecules, (e) Possible communication (electron, energy, and spin transfer) between encapsulated guest and free molecules present in water, (f) Selective orientation and conformational pre-organization of the guest within the OA capsule, (g) Influence products distribution through controlling the free space within the capsule. Topics (a) to (g) relate to the understanding of OA as a reaction medium and associated dynamics of the guest@host complex while (h) and (i) deal directly with the PI's primary interest of controlling photoreactions in restricted spaces. The long-range scientific goal is to develop, on the basis of well-established rules of molecular organic photochemistry and supramolecular chemistry, a model to predict the photobehavior of organic molecules in restricted spaces.
The research proposed by Professor Ramamurthy will help train graduate students on several aspects of modern organic chemistry, physical organic chemistry and photochemistry. In addition to providing excellent training for the students associated with the project, Professor Ramamurthy has long been involved in fostering international collaborations, disseminating scientific information through edited books and guest edited journal special issues (in addition to refereed publications), giving invited talks at national, international conferences and universities and organizing national and international scientific conferences. He also serves the scientific community as a Senior Editor of Langmuir, an ACS journal. The PI has used his expertise in photochemistry to collaborate on writing two textbooks, (1) Principles of Modern Photochemistry: An Introduction and (2) Modern Molecular Organic Photochemistry with N. J. Turro, and J. C. Scaiano. In addition, the PI is currently developing a course titled "Being a Scientist" that includes topics such as scientific temper, ethics in science, mentor-student relationship, choosing scientific problems, writing, submitting and reviewing journal articles and grant proposals, developing oral and written communication skills, quality and quantity in scientific research, influence of citation index and impact factor, and the role of a scientist in society.
Photochemistry (chemistry activated with light) plays an important role in every day life beginning with our survival (photosynthesis), vision (rhodopsin), circadian rhythm etc. An understanding of the fundamentals of ‘Photochemistry’ is crucial to make progress in capture and storage of solar energy, cure deceases such as jaundice, cancer, etc. and to use light in everyday applications such as lithographic printing, writing and reading of CDs and bar codes, Lasik surgery etc. Organic chemistry that generally interprets the molecular behavior in terms of individual molecular structures is not sufficient to understand and predict molecular behavior in biological systems and in solid assemblies related to materials applications. In such systems one needs to focus on more than one interacting molecular structures and such chemistry is known as ‘Supramolecular Chemistry’. This project focused on combining the principles of supramolecular chemistry and photochemistry to mimic the bioactive supramolecular structures like enzymes on membrane surfaces. In the long run the knowledge accumulated from this study would help efficient utilization of light for beneficial purposes and find ways to control the harmful effects of light on the earth. By carrying out photochemical studies of molecules enclosed in small organic containers known as hosts, (specifically octa acid, cyclodextrins, cucurbiturils and crystals) and by combining the well-established concepts of molecular organic photochemistry and supramolecular chemistry, V. Ramamurthy of University of Miami has developed a model to predict the photobehavior of organic molecules in restricted spaces such as crystals, porous solids, and guest-host systems in water. The investigation comprised of synthesis of hosts, guests and photoproducts, identification of the photoproducts by modern spectral techniques, separation of photoproducts by modern analytical tools, measurements of excited state properties by steady state and time resolved spectroscopic techniques, characterization of guest@host complexes by sophisticated NMR techniques. Thus the research helped the PI to train graduate students on several aspects of modern organic chemistry, physical organic chemistry and photochemistry. Results of this project have been published in the form of referred articles in scientific journals. During the life of this project the PI co-wrote a textbook on Photochemistry that has critically summarized the existing knowledge in this area. In addition, the PI has given lectures on his ongoing research at national and international conferences and at universities. In addition he has given general lectures titled (1) Science and scientists, (2) Fame and shame, (3) Light and life and (4) Functional knowledge from life as a scientist at various university campuses within and outside USA both independently and as a part of the ‘American Chemical Society on Campus’ program designed towards fostering better scientists both within and outside USA. In addition he serves the scientific community by acting as a Senior Editor for Langmuir, a well-respected journal in the area of chemistry at interfaces.
