Novel Materials for Energy Conservation and Sensors

1. Novel Materials for Energy Conservation and Sensors Samantha D. Hastings, Qun Zhao, Jason L. Freeman, Justin T. Sheff, Samuel B. Owens Jr., Yuanli Zhang, Jianwei Wang, Christopher M. Lawson, and Gary M. Gray Department of Chemistry, University of Alabama at Birmingham, 901 14th St S, Birmingham, AL, 35294 Introduction Our group has been involved in a collaborative effort to develop new materials that can be useful in two areas, energy conservation and sensors. The element that unites these diverse topics of research is the study of the linear and non linear optical properties of novel materials. Specifically, we have developed a series of fluorescent molecules that fall into two classes, phosphorus-substituted bithiophenes and metallacrown ethers. This effort is headed up by University of Alabama at Birmingham (UAB) Chemistry and Physics researchers, and the work involves collaborative work with several NSF EPSCoR RII research thrusts. Other collaborators include research groups from the Chemistry Department of the University of Mississippi, the Chemistry Department of the University of Montevallo, and Redstone Arsenal. LEDs Sensor Protection • Light emitting Diodes (LEDs) are increasingly being incorporated into electronic devices including lights sources and electronic displays, as they are more energy efficient than the current technology. Phosphorus-substituted bithiophenes synthesized by our group have been shown to have high quantum yields in the blue region of visible light, making them candidates to be used in light-emitting diodes. • Optical Power Limiters are materials that can prevent eye and optical sensor damage. • All systems have a light intensity threshold for damage, therefore lasers and other sources of high energy light sources can render sensors permanently or temporarily ineffective. The criteria for OPLs are that most of the low intensity incident light passes through the material yet most of the high intensity incident light is absorbed by the material. F L U O R E S C E N C E Catalysis Sensing Element • AlkeneHydroformylation is an important industrial reaction that is responsible for the production of 15 billion pounds of aldehydes per year. The use of catalysts in these reactions greatly reduces the energy spent and waste produced. Our group has synthesized a remarkably versatile bimetallic catalyst that displays unprecedented tunability of the regioselectivity in the hydroformylation of styrene while maintaining high reaction rates. Decreasing the syn gas pressure greatly increases the selectivity for the linear aldehyde while increasing the syn gas pressure and adding an alkali metal salt greatly increases the selectivity for the iso aldehyde. • Molecular Sensors are molecules with a signature spectroscopic signal that can bind ions and small molecules. Once bound, the spectroscopic signal changes, resulting in a highly sensitive, quantitative method that can detect a variety of chemical species. 31P NMR, IR, and fluorescence spectroscopy can be used to monitor the binding event. Our group has rigorously studied the binding of alkali metal salts to a model metallacrown ether compound via 31P NMR. Our new approach to analyzing the binding allows both the number of solvent molecules displaced and the intrinsic binding constant to be calculated. These provided insight into the binding mechanism and may allow improved molecular sensors to be developed. Acknowledgments The authors would like to thank UAB-Chemistry and Physics Department, Nathan Hammer at the University of Mississippi, Houston Byrd at the University of Montevallo, Henry Everitt at the Redstone Arsenal, JunpengGuo at UAH, Army Research Laboratories Cooperate Research Agreement, GRSP NSF-EPSCoR Fellowship and NSF-EPSCoR UAB Center for Optical Sciences and Spectroscopies for funding and support.