Michael F. Mayer - US grants

As nanotechnology evolves, there will be a need in the future of nanoscopic plumbing or conduit, thus there will be a need for controlling bends within nanoscopic conduit. One method for constructing such conduit is by the controlled assembly of nanotubes. A few methods to joining inorganic nanotubes are known, however, no methods to form fittings for organic substances; this may present snags related to the lack of organic functionality. Organic nanoscopic conduit is well suited for incorporation into membranes for controlled transport or deposition of molecular substances and also for the separation of enantiomers. The specific aim of the research funded by this fellowship is to design and develop nanoscopic fittings in order to joint organic nanotubes at a 90 degree angle to form L and T-shape junctions. This will be achieved by forming molecular rods (composed of a porphyrin coordination polymer with a dendritic periphery) joined at a 90 degree angle, cross linking the periphery of the rod, and then coring out the center of the cylindrical structure-thus providing a unimolecular organic nanoscopic tube with controlled architecture.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The Organic and Macromolecular Chemistry Program in the Chemistry Division at the National Science Foundation supports Professor Michael F. Mayer at Texas Tech University whose
proposed research project is to establish new, controlled synthetic methods to access new compounds composed of interlocked molecular species and new polymeric materials with mobile slip-links (sliding crosslinks) and apply them to the study and advancement of the theory of rubber elasticity.
Materials composed of mechanically interlocked molecular-level species often possess novel and substantially different bulk physical properties than materials composed of identical but otherwise non-interlocked molecular-level species. Unfortunately, the current ability to controllably synthesize interlocked molecules is quite limited and synthetic control over the type of entanglement and degree of interlocking is virtually non-existent in macromolecular and polymeric species. This research will result in new processes for accessing classes of polymers known as polypseudorotaxanes, cyclic and acyclic polyrotaxanes, daisy-chain polymers as well as innovative polymeric materials with mobile slip-link crosslinks ? a novel type of polymer crosslink that has not been available in rubbery bulk materials but has been of great interest for several decades.

The new ability to produce polymeric materials with mobile slip-links (sliding crosslinks) will result in new materials which may be ideal candidates for experimental probing to aid development of theoretical models of polymer entanglements. This transformative methodology may, therefore, help advance the understanding of rubber-like elasticity in polymeric materials, a long-standing pursuit of polymer science. Furthermore, by virtue of the unique molecular structure of the proposed materials, the materials are expected to possess novel viscoelastic properties which may make them suitable for a variety of niche applications. The proposed educational activities center on digitally recording and uploading chemistry content to the internet. This will positively impact both the producers and the consumers of the content. The producers, for example chemistry majors, student affiliates of the ACS, undergraduate researchers and Welch Summer Scholars (high school students), will benefit from participating in a truly modern form of pedagogy. The farthest-reaching benefit will be for the consumers, identified as chemistry students, broadly defined, from local, national and international locations, who may freely participate in informal, cyber-enabled, inquiry-based chemistry education in both English and Spanish.

With this award from the Chemistry Research Instrumentation and Facilities: Multi-user (CRIF:MU) program, Professor Carol Korzeniewski and colleagues Christopher Bradley, Dominick Casadonte, Michael Mayer and William Nes from Texas Tech University will acquire a cyber-enabled premium-shielded 400 MHz NMR spectrometer. The proposal is aimed at enhancing research training and education at all levels, especially in areas of study such as (a) development of cobalt catalysts for hydrocarbon activation/functionalization, (b) photochemical studies of metal phenanthroline-based molecular assemblies, (c) synthetic, structural and reactivity studies on zwitterionic metal silanides, siloxides and silane dendrimers, (d) development of neuropeptide mimics and enantioselective synthesis using chiral N-phosphonyl imines, (e) preparation of mechanically interlocked polymeric materials, and (f) studies to unravel sterol biosynthesis.

Nuclear Magnetic Resonance (NMR) spectroscopy is one of the most powerful tools available to chemists for the elucidation of the structure of molecules. It is used to identify unknown substances, to follow the progress of chemical reactions, to characterize specific arrangements of atoms within molecules, and to study the dynamics of interactions between molecules in solids and in solution. Access to state-of-the-art NMR spectrometers is essential to carry out frontier chemistry related research and to train students in modern research techniques. The results from these NMR studies will have an impact on organic, materials, electronics and bioorganic chemistry research. The resources will be used not only for research activities but also for research training of undergraduate and graduate students including those from underrepresented groups.