Elucidating the Organic-OMS Interface and Its Implications for Solid Enantioselective Catalysts

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

Abstract Proposal Title: Elucidating the Organic-OMS Interface and Its Implications for Solid Enantioselective Catalysts Proposal Number: CTS-0624813 Principal Investigator: Daniel Shantz Institution: Texas Engineering Experiment Station Analysis (rationale for decision): Ordered Mesoporous Silica (OMS) organic hybrids have attracted great interest as potential heterogeneous analogues of homogeneous catalysts. This project will lead to a rigorous description of the inorganic-organic interface by using solid-state nuclear magnetic resonance (NMR) spectroscopy to determine: (1) the rotational mobility of groups attached to OMS surfaces, and (2) the local structure and conformation of the organic group with respect to the OMS surface. When coupled with catalytic testing, this work will show how structure and dynamics at the nanometer length scale influence reactivity, leading to new design paradigms for hybrid materials and their use in catalysis. This work will investigate chemically simple functional groups such as alkylamine groups attached to surfaces, surface tethered homogeneous catalysts such as Schiff bases (e.g. Al-salen), and short peptides which are of interest for enantioselective organocatalysis. The intellectual merit of this work is fourfold. A molecular description of the local structure (first) and dynamics (second) of organic groups covalently attached to ordered mesoporous silica surfaces and how they are affected by surface hydrophobicity, loading, and solvation is lacking. This type of information is essential to designing organic-inorganic interfaces in materials that are catalytically relevant. Third, how reactivity is modified by these local structural phenomena is not understood. Fourth, this knowledge will provide new paradigms for rationally designing organic-inorganic interfaces in general, and organic layers on ordered mesoporous silica for catalysis in particular. The broader impact of this work is also fourfold. First, the ability to relate local structure and dynamics to function will lead to more efficient design of organic-inorganic hybrids. The work proposed here relates specifically to organocatalysis and enantioselective reactions but will also be generally relevant to researchers in catalysis as well as impact fields including molecular recognition and separations. Second, the ability to design enantioselective solid catalysts, particularly those without a metal center, will have implications for both the fine chemicals and pharmaceutical industries. Third, the curriculum development will introduce Chemical Engineers to solid-state NMR methods. Fourth, this research will involve undergraduate students through existing programs on the Texas A&M campus and the results of this work will also be disseminated through a K-12 program.