Xu H.,Japan Institute for Molecular Science
Nature Materials | Year: 2016
Progress over the past decades in proton-conducting materials has generated a variety of polyelectrolytes and microporous polymers. However, most studies are still based on a preconception that large pores eventually cause simply flow of proton carriers rather than efficient conduction of proton ions, which precludes the exploration of large-pore polymers for proton transport. Here, we demonstrate proton conduction across mesoporous channels in a crystalline covalent organic framework. The frameworks are designed to constitute hexagonally aligned, dense, mesoporous channels that allow for loading of N-heterocyclic proton carriers. The frameworks achieve proton conductivities that are 2–4 orders of magnitude higher than those of microporous and non-porous polymers. Temperature-dependent and isotopic experiments revealed that the proton transport in these channels is controlled by a low-energy-barrier hopping mechanism. Our results reveal a platform platform based on porous covalent organic frameworks for proton conduction. © 2016 Nature Publishing Group
Abe M.,Hiroshima University |
Abe M.,Japan Institute for Molecular Science |
Abe M.,Japan Science and Technology Agency
Chemical Reviews | Year: 2013
Recent development in diradical chemistry are summarized in detail. Diradicals are long-known chemical species, but they continue to be fascinating molecules because of their inherently high reactivity and their potential molecular functions, which are mainly derived from their small HOMO-LUMO energy gaps. Kinetic stabilization and thermodynamic stabilization have made it possible to isolate diradical species. The terminology of singlet and triplet states in diradicals is derived from the number of energy level in diradicals under an external magnetic field. The triplet state is the ground-state spin multiplicity for diradicals in which a large overlap integral exists between the two energetically degenerate molecular orbitals that are occupied by two electrons. Localized diradicals are key intermediates in processes involving the homolytic bond-cleavage and -formation reactions of cyclic compounds.
Taira T.,Japan Institute for Molecular Science
Optical Materials Express | Year: 2011
Transparent laser ceramics have been demonstrated to offer tremendous processing and design advantages in the diode-pumped solidstate laser field. Successfully developed composite Nd:YAG/Cr:YAG ceramics realized a multi-megawatt three-beam output microchip laser for efficient engine ignition. After a progress review for Giant Micro-photonics, including their wavelength extension with micro-domain controlling, we'd like to discuss the next generation of high-brightness lasers based on anisotropic ceramics. The capability of transparent anisotropic ceramics, by using a new crystal orientation process based on large magnetic anisotropy induced by 4f electrons, offers extremely high-power laser materials such as RE:FAP and patterning process for multi-function integrated monolithic solid-state lasers. © 2011 Optical Society of America.
Kurashige Y.,Japan Institute for Molecular Science
Molecular Physics | Year: 2014
Recent advances in quantum chemical density matrix renormalisation group (DMRG) theory are presented. The DMRG, originally devised as an alternative to the exact diagonalisation in condensed matter physics, has become a powerful quantum chemical method for molecular systems that exhibit a multireference character, e.g., excited states, π-conjugated systems, transition metal complexes, and in particular for large systems by combining it with conventional multireference electron correlation methods. The capability of the current quantum chemical DMRG is demonstrated for an application involving the potential energy curve of the chromium dimer, which is one of the most demanding multireference systems and thus requires the best electronic structure treatment for non-dynamical and dynamical correlation as well as large basis sets. © 2013 Taylor & Francis.
Aono S.,Japan Institute for Molecular Science
Advances in Microbial Physiology | Year: 2013
Sensor proteins play crucial roles in maintaining homeostasis of cells by sensing changes in extra- and intracellular chemical and physical conditions to trigger biological responses. It has recently become clear that gas molecules function as signalling molecules in these biological regulatory systems responsible for transcription, chemotaxis, synthesis/hydrolysis of nucleotide second messengers, and other complex physiological processes. Haem-containing sensor proteins are widely used to sense gas molecules because haem can bind gas molecules reversibly. Ligand binding to the haem in the sensor proteins triggers conformational changes around the haem, which results in their functional regulation. Spectroscopic and crystallographic studies are essential to understand how these sensor proteins function in these biological regulatory systems. In this chapter, I discuss structural and functional relationships of haem-containing PAS and PAS-related families of the sensor proteins. © 2013 Elsevier Ltd.