The University of Tokyo · Chemistry
Professor Hiroshi Masai's research lab specializes in the design and synthesis of functional molecular materials for advanced electronic and optoelectronic applications. The lab focuses on insulated molecular wires, metallopolymers, and supramolecular architectures—particularly those incorporating transition metals like Ru(II) and Pt(II)—to achieve enhanced charge transport, phosphorescence, and stimuli-responsive behavior. Key research directions include the development of self-assembled, macrocycle-protected conjugated systems, rotaxane-based molecular machines, and stimuli-responsive polymers with tunable optical and electronic properties.
Figures are computed from collected data and may differ slightly.
We report, herein, the design, synthesis, and properties of new materials directed toward molecular electronics. A transition metal-containing insulated molecular wire was synthesized through the coordination polymerization of a Ru(II) porphyrin with an insulated bridging ligand of well-defined structure. The wire displayed not only high linearity and rigidity, but also high intramolecular charge mobility. Owing to the unique properties of the coordination bond, the interconversion between the m
Controlling the thermal fluctuations and molecular environment of a phosphorescent polymer backbone is vital to enhancing its phosphorescence intensity in the solid state. Here, we demonstrate enhanced phosphorescence control through a systematic investigation of cyclodextrin-based insulated platinum-acetylide polymers with well-defined coverage areas. Modification of the coverage areas revealed two unprecedented effects of macrocyclic insulation on phosphorescence behavior. First, the insulatio
Biological systems are known to spontaneously adjust the functioning of neurotransmitters, ion channels, and the immune system, being promoted or regulated through allosteric effects or inhibitors, affording non-linear responses to external stimuli. Here we report that an insulated conjugated bimetallopolymer, in which Ru(II) and Pt(II) complexes are mutually connected with insulated conjugations, exhibits phosphorescence in response to CO gas. The net profile corresponds to a sigmoidal response
We describe a new concept for rotaxane synthesis through intramolecular slippage using π-conjugated molecules as rigid axles linked with organic soluble and flexible permethylated α-cyclodextrins (PM α-CDs) as macrocycles. Through hydrophilic-hydrophobic interactions and flipping of PM α-CDs, successful quantitative conversion into rotaxanes was achieved without covalent bond formation. The rotaxanes had high activation barrier for their de-threading, so that they were kinetically isolated and d
Abstract Insulated molecular wires, π-conjugated molecules insulated by nonconductive macrocycles, have been regarded as key components in the field of single-molecule electronics. Their various functionalities were attributed to their π-conjugated systems and enhanced by their macrocyclic insulation. We have recently proposed that the linked-structures resulting from π-conjugation with cyclic molecules, especially with permethylated cyclodextrins, were effective for preparing various types of f
An insulated Pt-acetylide complex was incorporated into a polymer network as a crosslinker to afford a phosphorescent gel.
Interest in macromolecules has increased because of their functional properties, which can be tuned using precise organic synthetic methods. For example, desired functions have been imparted by controlling the nanoscale structures of such macromolecules. In particular, compounds with interlocked structures, including rotaxanes, have attracted attention because of their unique supramolecular structures. In such supramolecular structures, the mobility and freedom of the macrocycles are restricted
Photopolymerization and photoprocessing are core technologies for molding and tuning polymer materials. However, they are incompatible with single materials owing to their contradictory photoreactivity. Herein, an acid-induced photocleavable crosslinker, a platinum-acetylide complex covered by permethylated cyclodextrins, enables the fabrication of photoprocessable materials via photopolymerization with N-(2-hydroxyethyl)acrylamide. The polymer networks are molded by 365 nm irradiation as well a
Abstract Although photodegradability is promising for on‐demand tuning of material properties, phototuned materials cannot be utilized under ambient light irradiation owing to their photoinstability. Herein, a novel photostable gel that photodegrades only in the presence of an acid is fabricated. The unique reactivity of a supramolecular platinum‐acetylide complex is uncovered to incorporate into poly(methyl methacrylate) gel as the cross‐linker to exhibit softening and swelling under simultaneo
The development of new tuning methods for π-conjugated insulated molecular wires with strictly defined axle lengths as well as positions and degrees of macrocycle coverage would provide unprecedented insight into insulation effects in functionalized materials. Herein, iterative reactions of oligo(phenylene ethynylene) (OPE) linked with permethylated α-cyclodextrins were carried out to fabricate insulated molecular wires with a defined length and insulation in desired areas. Insulated OPEs were e
The modulation of molecular interaction with a [3]rotaxane structure enabled a luminescent thermoresponse with high sensitivity over a wide temperature range. Herein, a pyrene moiety was encapsulated by permethylated α-cyclodextrins and was introduced into a polymer network material of poly(vinyl alcohol) as a cross-linker. The luminescence nature associated with the pyrene moiety was continuously switched from a static pyrene-pyrene excimer emission mode at 193 K to a dynamic pyrene-dimethylani
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