The main purpose of this project is to continue the development and testing of a new class of functional solid state materials based on structures that have a static, lattice-forming supramolecular or metalo-organic coordination frames, linked to dipolar molecular components capable of changing their orientation in response to external fields. The desired molecular components are structurally analogous to macroscopic compasses and gyroscopes, and their crystalline aggregates are expected to form dipolar rotary arrays with many interesting properties. It is predicted that changes in molecular and crystallographic symmetry will lead to materials with spontaneous dipolar order, either ferroelectric or antiferroelectric, with a number of states (orientations) that will depend on the rotational symmetry order. Recent advances in communication technologies have stimulated much interest in the field of photonics, including materials with tunable transmittance, refraction, polarization, and color. The students involved in aspects of this project include three women and two Hispanics. A post-doctoral NSF discovery corps fellow who participates in this project leads the research group in outreach activities, which involves interactions with teachers at Abraham Lincoln High School of the Los Angeles Unified School District, with a student body that is 85% Hispanic and 15% Asian.
Non-Techical:
Advances in communication technology continue to have a very strong impact in all aspects of our daily lives, including improvements in entertainment, education, and national security. In this context, one of the most promising areas for future development is the field of photonics, where light takes the place of electricity to help us read-write, store, process, and transmit information. While light has many interesting properties (color, polarization, brightness, does not produce heat, etc.), it is still quite difficult to handle and manipulate. The main purpose of this project is to develop and test a new class of functional solid state materials designed to help control the passage of light by using structures with molecules that change their state of motion and orientation in response to electric fields. The desired molecules are structurally analogous to macroscopic compasses and gyroscopes, and are able to orient themselves towards the strongest fields or to change their state of motion when an external force is applied. The students involved in various aspects of this project are trained in cutting-edge research techniques while developing some of the newest technologies. A post-doctoral NSF discovery corps fellow who participates in this project leads our research group in outreach activities, which currently involves interactions with teachers at Abraham Lincoln High School of the Los Angeles Unified School District, with a student body that is 85% Hispanic and 15% Asian.
Light plays a key role in many current and future technologies. Examples range from bar code readers, flat panel displays, and 3D television, to fiber optics communication and optical computers. The use of light in these and other technologies relies on, among other factors, our abilities to manipulate its intensity, color, polarization, direction, and velocity. With funds provided by this grant we have developed a new class of materials that are built with a collection of molecular machines that work together to accomplish these tasks. We have designed and constructed a series of molecules that emulate the properties of macroscopic compasses and gyroscopes, and we have devised a new strategy to manipulate the properties of incident light by controlling their mobility with external electric and magnetic fields. Like their macroscopic namesakes, molecular compasses and gyroscopes have a rigid box with a small rotating group inside that is connected at the center of the assembly. The rigid nature of the encapsulating box facilitates the formation of an orderly but static molecular array, and the rotating group acts like the needle of a macroscopic compass or the spinning disc of a gyroscope. Molecular compasses and gyroscopes are deliberately shaped to self-assemble in the solid state in a manner that all the rotors are parallel to each other, such that they are all able to point the same way. Using strong external fields we can control the direction of all the molecular needles, just as one can reorient the direction of a compass needle using a toy magnet. By changing the direction and intensity of the external field we can change the number of molecular compasses that point in a particular orientation, and with the proper components, we will be able to control the amount of light transmitted, its color, and some other properties. Some of the challenges addressed in the last few years of this project involve the design and optimization of these crystalline solids with moving parts, which we named "amphidynamic crystals". We have implemented methods to determine the rotation of the molecular rotators and we have shown that rotation can vary from zero to over a billion rotations per second. We have also studied the properties of some crystals as a function of external fields. Students involved in this project receive a rigorous training in the most current areas of materials science and future technologies. Students learn how to bridge the gap between molecular and materials design and their implementation in new devices. This project has attracted talented American women and men from all cultural and ethnic backgrounds, many of whom are now contributing to the economy of the country by joining top technology companies and educational institutions.
