CAREER: Tubularenes: A Novel Class of Conjugated Molecular Nanotubes

William Marsh Rice University, Houston TX

Investigators

Abstract

Dr. Raúl Hernández Sánchez of the University of Pittsburgh is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry at the NSF to design, synthesize, and characterize nanomaterials composed of cylindrical conjugated organic molecules. These molecules form well-defined wire-like nanosystems with diameters around one nanometer, which is about 100,000 times smaller than a human hair. The project goals are to gain fundamental understanding of the chemistry involved and to enable the development of critical nanocomponents, with potential long term practical applications, for example, in electronic device miniaturization and membrane technology for liquid or gas separations. Students working on the project will gain technical skills across many disciplines from macromolecular chemical synthesis and product characterization to basic computational analysis. In addition, Prof. Hernández Sánchez and his students are actively involved through the Alliance for Diversity in Science and Engineering at Pittsburgh in inspiring members of underrepresented minorities to pursue STEM careers and in increasing general public awareness of science through symposia, local fairs and conventions. Prof. Hernández Sánchez is also active as faculty in Eureka Street Corporation dedicated to mentor applicants from underrepresented minorities and in Clubes de Ciencia México (Science Clubs Mexico) to conduct STEM Workshops for high school and undergraduate students from Chihuahua City, México. In this project, Professor Hernández Sánchez and his research team are supported to develop synthetic protocols to construct molecular wire-like systems termed tubularenes. The project will follow bottom-up template-assisted approaches to build conjugated nanotubes using select aromatic building blocks and macrocycles end-caps. The selected templates would ideally hold the precursor aromatic building blocks close in space to limit their degrees of freedom and orient them in a geometry that best promotes the desired reactivity. The first aim of the project seeks to validate the scaffolding approach by testing a range of aromatic building blocks and macrocycles. The second aim will focus on the promotion of axial conjugation. Strain energies of intermediates and expected products will be assessed to inform the design of viable synthetic routes for radially and axially extended conjugated surfaces. The third aim involves the incorporation of heteroatoms into the aromatic framework as dopants to tune electronic structure. Computational chemistry will be used throughout to guide the project and allow for better informed design/modification/tuning decisions. 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.