RUI: Molecular Topology Directed Molecular Assembly Using Crystalline Quasiracemates

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PART 1: NON-TECHNICAL SUMMARYMany functions of solid materials require particular molecules to selectively interact with each other. This specific interaction between molecules often arises from a blend of both strong and weak forces that control the orientation of the component building blocks. While strong interactions have achieved considerable attention, chemical features that produce less manageable motifs via less well defined or weak contacts are also important to the overall molecular recognition process. Molecular shape is one such feature. This program, directed by Professor Kraig Wheeler and anchored by a research team of undergraduate students at Whitworth University, creates target molecules that align to form crystals by using the structural feature of molecular shape. A central aim of the research, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, is to develop diverse families of materials that exploit the shape space of components that form predetermined assemblies. This basic research may open the door for the future design of functional solids via exploiting molecular properties of the building blocks. Through integration of the research with undergraduate research training in synthesis, crystal growth, structure determination, and video-assisted microscopy, students will be prepared as scientists for careers in STEM fields. PART 2: TECHNICAL SUMMARYUntangling the details of molecular recognition continues to hold intense interest to a wide range of science disciplines. The manner in which molecules organize into energetically favorable solids often relates to complementary electrostatic non-bonded contacts and best-fit scenarios. This research, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, focuses on understanding structural boundaries of molecular shape to the molecular recognition process by using the quasiracemate approach for constructing bimolecular solid compounds. Chiral building blocks formulated from known organic precursors will be synthesized via amino acid, carboxylamide, and naphthyl derivatives. While the study of quasiracemic materials has now progressed to an established science, the intimate details of assembling pairs of quasienantiomers remains relatively unknown. This proposal explores how increasing crystal lattice stabilization via charge-assisted non-bonded contacts and an increased size of molecular framework effectively allows for greater structural variation of the quasienantiomeric components. Lattice energy calculations combined with crystallographic, video-assisted thermomicroscopy, and calorimetric studies will be used to assess the ability of these materials to form quasiracemic assemblies. The research group seeks a systematic understanding of the definition of "isostructural" in the context of quasiracemate formation that may prove useful for probing the topological features responsible for molecular recognition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.