Coordination programming: science of molecular superstructures towards chemical devices

“Coordination programming” is a new chemical term invented recently in Japan. This new concept was the inspiration for a 5-year project entitled “Coordination Programming: Science of Molecular Superstructures towards Chemical Devices” which began in September 2009 and was funded by a Grant in-Aid for Scientific Research on a Priority Area from MEXT, Japan. The project is headed by Professor Hiroshi Nishihara, University of Tokyo, and involves more than 100 researchers.

Sophisticated biological phenomena such as photosynthesis or enzymatic reactions rely upon a series of high efficiency systems whose functions combine light harvesting, redox reactions, transport, and molecular conversions. Such molecular functions have excited chemists for a long time. On the other hand, electronic and photo-switchable devices are usually constructed from simple molecular systems such as low nuclearity complexes, liquid crystals or conductive polymers. Such systems can, however, be extended to increase their size or vary their electronic state through, for instance, macromolecular, integrated molecular, supramolecular and molecular organization, thus allowing the functional interconnection of molecular components to occur in expanded fields. However, we are still unable to effectively tune the functionality of an extended molecular system by coordination chemistry. At the same time, technology for characterizing and patterning sub-nano, nano, and meso structures has been established using lithography and scanning probe microscopy. The realization of artificial neural networks based on molecular components, one of the most important research goals of this century, is attainable by the downstream integration of complex molecular systems and surface-addressing technologies. However, there remains a gap between the molecular functionalities and their device integration. We created a new area, Coordination Programming, through the incorporation and collaboration of active researchers with top-level skills in broad areas in order to bridge this gap.

“Coordination Programming: Science of Molecular Superstructures towards Chemical Devices” comprises various areas of research. Fundamental scientific studies for the generation of materials (molecular superstructures) with precisely determined structures in the nano- and meso-scopic regions are being developed through the application of coordination chemistry in conjunction with material science, surface chemistry and peripheral fields such as future electronic devices. At its core, “programming” entails the molecular design of materials in which the interplay between transition metal ions is mediated by both direct interactions and through the chemical superstructure, thus coordination programming is an essential approach to the construction of systems with targeted physical and chemical functionalities. Coordination programming includes four primary research areas:

(i) Interface programming: surface-immobilized multi-component molecular systems prepared by coordination programming, which exhibit unique device-applicable functionalities based on the combination of physical, chemical and biological functions of the components.

(ii) Cluster programming: multinuclear transition metal cluster systems, which display bistable physical properties, switchable through the application of various external stimuli, such as temperature, light, electric field, and magnetic field among others.

(iii) Supramolecular programming: molecular superstructures based on supramolecular systems for advanced energy and/or chemical conversion, amplifying electron and/or energy transfer without any loss.

(iv) Biochemical programming: bio-inspired multiple molecular systems in which electronic communications between molecular components generate new reactivities or physical characteristics as emergent properties.

The project on “Coordination Programming” will end in March 2014. However, we believe that this project is just the beginning of a new field of coordination chemistry, which will be developed by linking coordination chemistry to various other fields of chemistry, as well as to the fields of physics, biology, and material science in research centers across the world.

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