An investigation of the effect of bridging groups on the magnetic properties of high-spin organic molecules will be conducted. Emphasis will be placed on defining the structural parameters which are necessary to maximize coupling of multiple spin centers in organic molecules. A program of targeted synthesis of specifically defined high-spin precursors will be coupled with measurements of the magnetic properties of the resultant high-spin molecular species: this will establish the type of bridging groups which most effectively couple via an intramolecular process. A highlight of the research will be the development and subsequent evaluation of magneto-optical switches which are capable of rapid changes in magnetic properties when exposed to appropriate wavelengths of light. %%% This grant from the Organic Dynamics Program supports the continuing investigations of Professor D. A. Dougherty at the California Institute of Technology. These studies will be focused toward the synthesis and design of organic molecules which exhibit magnetic properties when exposed to heat or light. The target molecules, which are effectively known as organic magnetic switches, will be evaluated for their magnetic properties by utilization of specialized equipment designed to operate at liquid helium temperatures. Advances in this field will provide the basic information required to develop organic magnets with unique optical properties for utilization in electronics applications.