Encouraging pi-electron delocalization through boron-based heteroaromatic subunits

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In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor John D Tovar of the Department of Chemistry at Johns Hopkins University will develop new classes of boron-based molecular materials that have properties akin to traditional inorganic semiconductors. These organic molecules have emerged as attractive components for contemporary organic electronics, with applications spanning anion sensing, non-linear optics and light-emitting devices. Students in these areas will play critical roles in the future developments both on the commercial and academic fronts. One unusual and attractive element of this particular research program is the training environment it will offer to undergraduate and graduate students. Outside of the training in synthetic organic chemistry requisite for obtaining specific pi-conjugated materials, students will be exposed to optoelectronic characterization methods and will serve as intimate participants in collaborative efforts to make new devices. Under the umbrella of this project, the PI will help to increase participation of women and underrepresented minorities in advanced degree programs through continued support of research opportunities at the graduate and undergraduate level.Boron-based pi-electron materials have emerged as attractive components for contemporary organic electronics. Typical structural motifs through which pi-conjugated organoboranes can be included into organic electronic materials consist of triarylboranes as well as boron-containing annulenes with aromatic (such as formally charged azaborine and boratabenzene rings) and antiaromatic (such as borole rings) character. Lacking on this list are formally neutral boron aromatics such as those exemplified by the borepin ring. A primary scientific motivation for borepin inclusion into organic electronic scaffolds is to understand fundamental issues about how the weak borepin aromaticity would influence pi-electron delocalization and polarization given that these molecules would be expected to maintain high degrees of "cyclic polyene" character yet still provide some degree of aromatic resonance stabilization energy. To understand how these unique conjugation features might be exploited for new materials designs, new borepin architectures with varying degrees of intra- and inter-molecular electronic delocalization will be studied. These borepin scaffolds will be fully characterized electronically to understand their novel aromaticities and polarizabilities, and they will be transitioned into collaborative efforts to explore a variety of organic electronics applications.