We are privileged to launch this new research area entitled “Condensed Conjugation Molecular Physics and Chemistry: Revisiting “Electronic Conjugation” Leading to Innovative Physical Properties of Molecular Materials” as a memorable first group of Grant-in-Aid for Transformative Research Area (A) in 2020 supported by MEXT, Japan. We are also pleased to work together to cause a paradigm shift of electronic conjugation in molecular science, as we all stepped into sciences by the time of “Paradigms in Science” defined clearly by Kuhn and accepted widely by scientists. The concept of electronic conjugation: this is our target paradigm which we would like to transform herein. To date, well-sophisticated formulations have been established to represent and interpret electronic conjugation in molecular materials, and we might have no debt on the representations as energy gain of electron delocalization over molecular skeletons. In contrast to the long-lasting concepts of electronic conjugation defined explicitly based on the potentials from point charges of nuclei and non-point charges of electrons, we are now seeking a clear explanation of electron delocalization over molecular aggregates and intermolecular spaces. We will challenge the conventional concept of electronic conjugation by establishing the new class of electronic conjugation referred to as “X”-conjugation in the present research project. How surprising physical properties turn out in molecular systems with “X”-conjugation; all we look forward to. We will provide a simple and explicit formulation for the clear explanation of “X”-conjugation. Since the first concept of electronic conjugation was suggested by Thiele in 1899, “X”-conjugation must be proposed not only as a simple extension of the concept but also as a distinctly new one lasting until the next century.
Head Investigator Kyoto University Shu SEKI
About Condensed Conjugation
Diamond exhibits higher charge carrier mobility than that in crystalline silicon. This unique electronic property of diamond reminds us the intrinsic predominance of “short” σ-bonds between carbon atoms and hence the potential of further shorter multiple bonds in achieving high electronic density of states (DOS). The use of designed electronic conjugation is rather natural to realize the future materials with exceptional electronic properties, where “condensation of electronic states” (condensed conjugation) will play a key role via an ultimate shrinkage of intermolecular spaces and filling the spaces with electrons as well as electronic states. This Research Area will establish a novel concept of intermolecular electronic conjugation, referred to as “X”-conjugation, by revisiting thoroughly the longitude and latitude in the development of “conjugation” in chemistry. Starting from the precise design of organic molecules with minimum intermolecular spaces, thermal fluctuations in the condensed phases of molecular systems will be controlled perfectly by the wide-range/spatial alignment of intermolecular interactions as well as the leading-edge energy dissipation theory. A series of unique assessment techniques of opto- and magneto-electronic properties is the central complex of the current research project, pioneering the unprecedented properties of molecular systems with “X”-conjugation. We will address this final target through the following strategies: (1) shrinking the intermolecular spaces to the limit (0.3 nm) by design of molecules, (2) aligning programmatically the wide dynamic-ranging intermolecular interactions that control the thermal fluctuations of molecules, and (3) loading electrons/spins onto molecules and realizing new electronic states that contribute to the overall high DOS. We believe the transformative research toward “X”-conjugation is achievable only by mutual translational research between the scientists in organic chemistry and solid-state physics.
A01 “X”-Conjugation beyond π-conjugation
We establish a novel concept of intermolecular electronic conjugation, “X”-conjugation, via precise design and synthesis of novel molecular skeletons with well-confined intermolecular spaces and electronic structures.
A02 Embodiment of “X”-conjugation by designed intermolecular interactions
We realize molecular systems with the perfectly controlled wide-range/spatial alignment of intermolecular interactions to overcome thermal fluctuations in closely packed molecular systems.
A03 Precise analysis of “X”-conjugation in condensed phases
We serve as the central complex of cutting edge assessment techniques of opto- and magneto-electronic properties of molecular materials with “X”-conjugation in condensed phases.
A04 Toward unprecedented properties of “X”-conjugation
We achieve extraordinarily high density-of-states (DOS) in the molecular substances by the implementation of “X”-conjugation into low dimensional structures as well as interfacial states.