Our group has pioneered an increasingly general synthesis platform for a range of functional molecules including molecular nanocarbons, π-conjugated organic materials, pharmaceuticals, and small molecules for plant biology and chronobiology. The uniqueness of our approach can be seen from the fact that most of the game-changing functional molecules that we have created were rapidly synthesized or discovered by our unique and powerful C-H activation catalysts and reactions.
During the last 10 years in Nagoya, the Itami group has focused on addressing some of the grand challenges in the chemistry of arene-assembled molecules. Our endeavors have led to (i) the development of new catalysts for C-H activation/coupling; (ii) the rapid synthesis of pharmaceuticals and natural products; (iii) the discovery of new synthetic bio-molecules particularly for plant biology and chronobiology; (iv) the development of optoelectronic π-materials; and (v) the controlled bottom-up synthesis of nanocarbons such as carbon nanotubes, graphene nanoribbons, and three-dimensional nanocarbons.
C-H Activation/Coupling for Ideal Chemical Synthesis
The activation and transformation of ubiquitous but inert carbon-hydrogen (C-H) bonds in organic molecules not only represents an important and long-standing goal in chemistry, but also has far-reaching practical implications. The Itami group has developed a number of unique and efficient catalysts for C-H activation/coupling making biaryls and heterobiaryls from unfunctionalized aromatic molecules. We have also developed a catalyst toolbox that can directly arylate almost all types of C-H bonds in heterocycles by catalyst control. Based on these catalysts, we successfully established general synthetic schemes for accessing privileged multiply arylated thiophenes, pyrroles, thiazoles, benzenes, and pyridines in a programmable manner.
These direct activation-transformation methods not only contribute to the realization of greener chemistry, but also unlock opportunities for markedly different strategies in synthesis and accelerates discovery of a range of functional molecules (which we actually demonstrated by ourselves). So far, six catalysts, ligands, and reagents for rapid chemical synthesis have become commercially available.
Synthesis of Bio-functional Molecules
The C-H coupling technologies and catalysts developed in the Itami lab allow the rapid synthesis of a number of biologically active compounds and pharmaceutically relevant molecules. In particular, some of the most recent results from the Itami group on the discovery of novel potent inhibitors of important enzymes make it clear that a truly efficient catalyst can have a huge impact in biology. Currently, a number of pharmaceutical and agricultural companies as well as chemical industries have already started to use our catalysts on a daily basis.
In the Institute of Transformative Bio-Molecules (ITbM), we are applying our catalysts and reactions to synthesize/develop key molecules that precisely control or visualize biological systems. Our representative targets include (i) molecules that control plant growth, (ii) molecules that modulate biological clocks of animals and plants, and (iii) molecules that realize innovative bio-imaging.
Synthesis of Organic Materials
The development of novel optoelectronic materials is another important field of our research. We planned and executed an efficient synthesis of a series of fascinating π-electron systems using catalysts (mostly by C-H coupling). Representative molecules include tri- and tetraarylethene-based conjugated molecules, heteroarene-core starburst π-systems, hexaarylbenzenes, and highly functionalized fullerenes. Our group not only constructed chemical libraries of extended π-systems, but also succeeded in discovering a number of interesting materials (full-color fluorescent materials, fluorescent nanoparticles, and solvatofluorochromic materials) as well as interesting photophysical phenomena such as aggregation-induced enhanced emission, polymer-induced emission, and generation effect in dendrimer photophysics.
The design and synthesis of as-yet largely unexplored nanocarbons as structurally well-defined molecules are another core project in the Itami group. For example, we accomplished the modular, size-selective, and scalable synthesis of short sidewall segments of armchair and chiral carbon nanotubes (CNTs) such as cycloparaphenylenes (CPPs), and uncovered unprecedented physical properties of these carbon nanoring molecules. The synthetic route was so effective, that several CPPs are now commercially available from Tokyo Chemical Industry Co. and Kanto Chemical Co. Moreover, we have succeeded in the diameter-selective synthesis of CNTs using CPPs as seeds. By choosing the diameter of the CPPs used as the seed, CNTs of the same diameter can be selectively synthesized.
Our group has also contributed to the bottom-up, controlled synthesis of structurally uniform nanographenes. Our simple yet powerful palladium catalyst [Pd(OAc)2/o-chloranil] can catalyze the regioselective aromatic π-extension (APEX) of polycyclic aromatic hydrocarbon. This methodology can be applied to various planar and geodesic PAHs and the controlled synthesis of nanographenes is becoming realistic.
In addition to the controlled synthesis of CNTs (1D nanocarbons) and graphene nanoribbons (1D/2D nanocarbons), we created completely novel, 3D curved nanocarbons. We accomplished the synthesis of a novel warped nanographene that contains both positive and negative curvatures on its π-surface. These warped nanographenes have an uneven structure that is unique and clearly distinct from any other nanocarbon synthesized so far, and are expected to possess unprecedented functions.
In the JST-ERATO Itami Molecular Nanocarbon Project, we combine chemical and physical methods to achieve the controlled synthesis of well-defined uniquely structured nanocarbon materials, and conduct interdisciplinary research encompassing the control of molecular arrangement and orientation, structural and functional analysis, and applications in devices. Our goal is to design, synthesize, utilize, and understand nanocarbons as molecules.