Sequence Programmable Triazine-Thymine Synthetic Ligands

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With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Christopher Alabi of Cornell University will design a chemical platform that can be programmed with multiple "sticky" side chains to create complementary pairs of chains similar to double-stranded DNA, that are able to assemble in the absence of water. A physical analogy is a beaded necklace with black and white beads that can bind to each other but not to themselves (i.e., black binds white but not black). Thus, the ability of a necklace with both black and white beads to stick to another beaded necklace will depend on the number of each type of beads in the necklace, the length of the necklace, and the positions of the black and white beads in each necklace. This work aims to design such a system on a molecular scale where the "sticky" black and white beads are molecules referred to as diaminotriazine and thymine, respectively. Mastering the design of these "sticky" chains that can undergo specific pairing in non-aqueous environment has the potential to open up new and exciting opportunities in the design and assembly of new functional materials. Educational and outreach activities will be integrated throughout this research project through a common theme that is focused on promoting peer-to-peer learning and empowering young aspiring scientists to take up leadership positions in communicating STEM (science, technology, engineering and mathematics) ideas to the broader public. Overall, the proposed project is expected to create new knowledge on how the composition and ordering of "sticky" building blocks along a polymer chain affects their ability to form selective molecular "velcros" that can be used in functional materials assembly. The central goal of this proposal is to design a programmable oligomer platform with molecular recognition motifs that can be used to encode information for hybridization in non-aqueous media. To design synthetic programmable ligands, the scalable sequence-defined oligocarbamate (SeDOC) platform will be exploited with diaminotriazine and thymine pendant binding motifs that dictate sequence, solubility, and hybridization strength. The proposed programmable SeDOC ligands will be designed to be soluble in organic solvents without the need for any additional reagents. Similar to DNA (2'-deoxyribonucleic acid), the number of interacting pendant motifs and length of the SeDOC backbone will define the coding space (i.e., sequence). However, unlike DNA, only a few binding motifs will be required for strong hybridization (as seen experimentally in a high Ka = high equilibrium association constant) due to the absence of a repulsive anionic backbone and the strong binding affinity of the diaminotriazine-thymine interaction in aprotic organic solvents. The proposal will investigate the effect of pendant group composition and sequence on hybridization strength toward the design of selective pairs of complementary SeDOC strands that can be used as ligands in various materials science applications.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.