Microscopes are very important tools for studying biological samples. However, most of the microscopes cannot measure the vibrational molecular imaging based on molecular information. At the moment, only two microscopes are measureable. One is the Raman microscope, and the other is IR microscope, those are complementary relations. But these are not perfect. Especially, the IR microscope has very low spatial resolution about 10 µm, because of the diffraction limit by the IR wavelength. This is a serious problem for a microscope. To solve this problem, we have developed IR super-resolution microscope with a sub-micrometer spatial resolution by using vibrational sum-frequency generation (VSFG) detection, and have reported the applications to various biological samples such as human hair, avian feather, living cells and so on. By using this microscope, we can observe not only the vibrational molecular image with high spatial resolution but also the molecular orientation and chirality images.

Salmon milt, defatted soybeans, crab and shrimp shells, and cowhide have been discarded as an industrial waste around the world. Therefore, DNA, soy protein, chitin/chitosan, and collagen, which are obtained from these materials, are sustainable resources. Our research using sustainable resources is as follows; 1) removal of harmful organic compounds; 2) selective accumulation of metal ion; 3) development of anhydrous proton conducting material; and 4) development of bioplastic with the biodegradable property.

Metal complexes can exhibit functions and physical properties not achieved by organic or inorganic compounds alone by appropriately selecting the central metal ion and designing the organic π-electron ligands surrounding it. The characteristics of these complexes enable effective sunlight harvesting and various catalytic reactions utilizing its energy. In our laboratory, we are developing visible light-driven redox catalysts for photocatalytic H₂ production and CO₂ reduction using metal-porphyrin complexes, which can harvest visible light and catalyze various reactions. In research on functions and physical properties, we are developing coordination polymers with unique magnetic and dielectric properties based on mixed-valence states using redox-active ligands. Furthermore, we are developing one-dimensional d-electroninc metals based on partially oxidized one-dimensional dinuclear platinum complexes that exhibit stable metallic states at low temperatures.

On the basis of FIA and LC in analytical methods using a liquid flow as much as possible to concern for the environment, we have studied to develop separation materials using carbon microparticles, analytical reagents specifically reacting with organic compounds, separation and analytical methods of dissolved organic compounds and bacteria in natural waters, a nano-LC which can separate and analyze an analyte in a sample volume of 1/1000000000 liters using a liquid flow volume of 1/1000000 liters, and separation and analytical methods using a self-reaction of sugars and amino acids.

Developing efficient organic photovoltaic cell devices have been increasingly important in the growing needs for inexpensive renewable energy. The molecular designs for organic photovoltaic materials required delocalized pi-electron systems and utility elements. To develop novel pi-electron systems for organic photovoltaic materials, we synthesized some novel donor/acceptor arrays with aromatic bisimide units, and measured their properties and self-assembly abilities. Recently, we also synthesized some N-atom containing pi-electron systems and revealed their photophysical properties and structures.

(Summary of our study)
The central goal of our group is to develop the new synthesis method of inorganic materials using water-soluble complexes and to search a new functional inorganic materials such as phosphors and transparent conducting materials, superconducting materials and so on.

(Main topics: Development of new phosphors)
Main topics of our study is development of new phosphors activated by blue and near-UV lights. Recently, we have reported new deep red-emitting oxide phosphors activated by blue light. We also investigate high functionalization of new host-excited phosphors based on functional oxides contained metal ions with s⁰ electron configuration.

Our research theme is development of new photoreaction using photoinduced electron transfer and its application to syntheses of functional materials. In present, we are working on (1) investigation of photochemical syntheses of indole derivatives which are considered to the important alkaloids widely found in nature, and (2) development of efficient photochemical synthetic methods for quinone imine dyes and their application. Because these target compounds indicate characteristic redox behavior, we also consider applying them to functional materials such as an OLED material while adopting their expected physical properties evaluated by quantum chemical calculation.

I’m working on migration behavior of elements in hydrosphere from a chemical view.

【Elucidation of mechanism of solid-liquid interfacial reaction】
One of the factors affecting migration behavior of elements in environment (especially in hydrosphere) is “adsorption of dissolved species on soil”. In recent years, it has been reported that various reactions to the adsorbed species occur. I’m trying to elucidate the mechanism of the reaction.

【Elucidation of nature of dissolved species in hydrosphere】
The dissolved species in hydrosphere is complex because several dissolved species coexists. I’m trying to elucidate the nature of the complicated dissolved species with theoretical calculation.

Transient absorption spectroscopy measures the changes in the absorbance of short-lived species generated by photo-irradiation, and gives us the information about dynamic processes in materials or chemical compounds. Rate constants are also determined by measuring time-profiles of the concentration of excited molecules.
By using this method, we can investigate molecular dynamics after photo-irradiation.