Supramolecular design of pi-electron functional materials

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Design and synthesis of new pi-electron functional materials allows answering fundamental physical chemistry questions, and play an enabling role in a wide spectrum of applications – from pigments and fluorescent labels, to semiconducting devices and electrochemical energy storage media. Our current understanding of optoelectronic properties of such materials is very advanced at the level of single molecules, but is rather limited in situations when the interaction of the molecules with each other and with interfaces are important. Our goal is to understand how electronic properties of organic matter arise and can be controlled at supramolecular level, and use this understanding to create novel types of semiconducting materials where an electronic conductivity arises as a result of programmable molecular self-assembly.***This discovery grant will continuously involve 5 graduate students and w undergraduates in research towards this goal through the following short-term 4 projects/objectives. We will:***1) Develop novel dynamic covalent chemistry suitable for self-assembly of ordered pi-conjugated polymers and covalent organic frameworks (COFs) under thermodynamic equilibrium. Our first target is aldol cyclization of cyclic ketones leading to rigid conjugated systems with dipole-dipole stabilization.***2) Develop omniconjugated building blocks that provide efficient electronic communication in several direction (no “cross-conjugation”). This will be accomplished by the use of (i) sexitopic and (ii) stable pi-radicals “nodes”, which will used as monomers for highly conjugated COFs and as cores for star-shaped molecular materials.***3) Gaining control of electronic properties in organic semiconductors via complementary hydrogen bonding. Coassembly of p- and n-type semiconductors and electronic polarization due to H-bonding will lead to strong band-gap modulation (giving rise to intrinsic semiconductors) and can lead to conducting channels that can be turned-on by interaction with H-bonding complementary pairs (including biomolecules).***4) Understanding the role of external factors (other than molecular or crystal structure) in controlling the charge transport through organic semiconductors. This will have an immediate impact on the current field of organic field effect transistors (FET), and is a critical step for the future development of self-assembled electronic devices.***The scientific impact of this work will be (a) new knowledge at the interface of organic chemistry and solid state physics, that will help stirring the current field of organic electronics along our long term vision and (b) novel electronically functional materials that will advance the current device technologies (FETs, solar cells), can enable novel applications, and will foster collaborations with materials physics and biochemistry groups.