The goal of this project is to address synthesis, characterizaton, and theory of a class of nonpolar electro-optic materials important to applications in image-plane electro-optic devices. The emphasis on synthesis includes several important systems. Noncyclic Terminated Lambda-shaped Molecules and Chromophores as new chromophores in the Crystal Violet family are being prepared so as to elucidate the origins of the large beta 2mm component already observed in these molecules. These chromophores are required for subsequent polymer synthesis. Macroheterocyclic Ring Chromophore are composed of large fully conjugated rings comprised of six or more individual heterocyclic rings. The size and symmetry of the macroheterocycle will dictate its nonlinear properties. Discotic Chromophores with Macroheterocycle or Longitudinally Twisted Chromophore Cores as discotic liquid crystals which having functional groups arrayed to provide the desired symmetry will be synthesized. A variety of discotic cores are will be examined including the truxones or the macroheterocycles described above. The longitudinally twisted discotic systems will be emphasized as a starting point. Helical Polymers will be created that incorporate as subunits the chromophores created as described above, especially the noncyclic terminated lambda-shaped molecules, by covalently linking them in the appropriate positions to create a polymer. The foldamers are one class of polymers that have the desired symmetry. The production of helical polymers requires first that the lambda-shaped components are available and so initial emphasis will be on the monomers and once they are in hand then the polymers will be prepared and evaluated. Where possible new and enhanced synthesis methods will be explored using using organometallic approaches. In the area of theory and design, chromophore design will be carried out using heuristic chemistry and quantum chemical calculations. Many of these calculations will be done using AMPAC and the GAMESS general atomic and molecular electronic structure system, and also using a program that can do semi-empirical calculations such as ZINDO which are better optimized for optical properties. These programs will be used to model the electro-optic response of the materials. Also, to address larger molecules and issues of molecular orientation heuristic chemical arguments will be adapted and used. Analytical, crude Monte Carlo and quantum chemical techniques will be used to study how chromophores align according to their molecular structure, and to analyze methods for achieving optimal alignment. Nonlinear optical characterization studies will be aimed at evaluating the nonlinear optical response and to verify models and mechanisms. Molecular level, bulk level and device-related studies will be carried out and will be used to guide further synthetic and theoretical work. Hyper-Rayleigh measurements will be employed to study molecular response for characterization as well as comparison to theory. Second harmonic generation and linear electro-optic measurements will be carried out on films.
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Research into these potential device materials, methods and concepts will contribute to new electro-optic technologies for optical data and image processing, and also to the knowledge required to promote electro-optics in general. This project integrates education and research in preparing graduate students and post-doctoral researchers for careers in optoelectonics or related critical workforce areas. Overall, the project will enhance development of scientists trained in interdisciplinary efforts in organic chemistry, physics, and optics. This project is co-funded by the Chemistry Division and the Division of Materials Research.
