Recent years have witnessed truly remarkable achievements in many fields of science and technology. Theoreticians are now seriously proposing the cognizant design and unidirectional fabrication of atomic and molecular assemblies on the nanometer scale with atomic precision. The design and construction of large-scale molecular arrays is clearly the enabling science for developing the true potential of nanotechnology. Along the way, however, many of the smaller molecules and assemblies which are intermediate in the fabrication of larger structures are fully expected to provide significant advances in a variety of areas, including optoelectronic applications, medicine and new advanced materials. This talk with focus upon the design, synthesis and proposed assembly of new architectural molecular synthons for nanostructural fabrication and the application of related synthons as new generations of nonlinear optical materials.
Most of the work thus far in nanoscale design has employed carbon as the primary structural element. Diamondoid and other bucky-based structures are receiving a great deal of attention due to their chemical and physical properties. Boron-based materials, however, have been comparatively neglected in this aspect. Of special interest are the polyhedral boron cluster systems, such as that shown in the figure (upper left). The design and fabrication of new three dimensional nanoscale molecular architectures may, however, best be accomplished through the use of these polyhedral and related building blocks, shown in the figure (lower left). When viewed from a nanoscale macrostructural perspective, these polyhedral cluster compounds and assemblies provide extraordinary structures with an unique array of critical nanostructural properties.
A new class of nonlinear optical (NLO) materials with potentially very high second-order responses and significantly improved chemical and physical properties has arisen from our investigations into polyhedral-based nanosystems. Calculated first hyperpolarizabilities (b) range from 34 x 10-30 esu to over 16,000 x 10-30 esu, with a variety of adjustable intermolecular parameters available. The calculational and experimental synthetic work on these and closely related new NLO systems will be presented in detail.