Fumitaka Ishiwari

When employing self-assembled monolayers (SAMs) for tuning surface and interface properties, organic molecules that enable strong binding to the substrate, large-area structural uniformity, precise alignment of functional groups, and control of their density are highly desirable. To achieve these goals, tripod systems bearing multiple bonding sites have been developed as an alternative to conventional monodentate systems. Bonding of all three sites has, however, hardly been achieved, with the co

Although the role of extracellular Ca(2+) draws increasing attention as a messenger in intercellular communications, there is currently no tool available for imaging Ca(2+) dynamics in extracellular regions. Here we report the first solid-state fluorescent Ca(2+) sensor that fulfills the essential requirements for realizing extracellular Ca(2+) imaging. Inspired by natural extracellular Ca(2+)-sensing receptors, we designed a particular type of chemically-crosslinked polyacrylic acid gel, which

A free-standing membrane consisting of a spirobiindane-based microporous polymer carrying trimethylammonium hydroxide groups exhibited good OH⁻ conductivity under vapour conditions.

A surprising terminal-group effect on the structural and physical properties of an amorphous polymer is reported. We recently demonstrated that triptycene derivatives with substituents at the 1,8,13-positions show specific self-assembly behavior, enabling the formation of a well-defined "2D + 1D" structure based on nested hexagonal packing of the triptycenes. Upon terminal functionalization with a 1,8-substituted triptycene (1,8-Trip), a liquid polymer, polydimethylsiloxane (PDMS, M_n

The synthesis of ladder polymers is still a big challenge in polymer chemistry, and in particular, there are few examples of conformationally flexible well-defined ladder polymers. Here we report an efficient and convenient route to conformationally flexible ladder polymers, which is based on a postpolymerization reaction of a rigid ladder polymer containing Tröger's base in its main chain. The postpolymerization reaction involves sequential <i>N</i>-methylation and hydrolysis for the Tröger's b

Abstract Effective induction of preferred‐handed helicity of polyacetylenes by pendant mechanically chiral rotaxanes is discussed. Polyacetylenes possessing optically active mechanically chiral rotaxanes in the side chains were synthesized by the polymerization of the corresponding enantiopure [2]rotaxane‐type ethynyl monomers prepared by the chiral‐phase HPLC separations. The CD Cotton effects revealed that the polyacetylenes took preferred‐handed helical conformations depending on the rotaxane

Abstract Triptycene, a rigid propeller-shaped molecule, was first synthesized in the early 1940s. More recently, many triptycene-containing polymers and molecular assemblies have been developed for a wide range of applications, including guest recognition, material transport, separation, catalysis, and as device components. The advantages of triptycenes lie in their ability to introduce a variety of functional groups on their three-dimensional backbone, with changes in substitution patterns as w

Although a large number of polymers that contain triptycene units in the main chains have been developed, no polymer design using 1,8-substituted triptycene has been reported to date. In this study, we investigated the properties of linear homo- and copolymers obtained by ring-opening polymerization of a triptycene monomer bearing a macrocyclic olefin linked at its 1,8-position and its copolymerization with cyclooctene, respectively. We found that the introduction of triptycene with this substit

Due to its unique physical and chemical properties, polydimethylsiloxane (PDMS) is widely used in many applications, in which covalent cross-linking is commonly used to cure the fluidic polymer. The formation of a non-covalent network achieved through the incorporation of terminal groups that exhibit strong intermolecular interactions has also been reported to improve the mechanical properties of PDMS. Through the design of a terminal group capable of two-dimensional (2D) assembly, rather than t

We recently reported that tetraphenylethene-appended poly(acrylic acid) derivatives (e.g., PAA-TPE_0.02) can serve as fluorescent Ca²⁺ sensors in the presence of physiological concentrations of biologically relevant ions, amino acids, and sugars. However, in the presence of basic proteins such as albumins, the Ca²⁺-sensing property of the polymer is significantly impaired due to the nonspecific adsorption of protein molecules, which competes with binding to Ca<sup

Surface passivation is key to the power conversion efficiency (PCE) of organic-inorganic lead halide perovskite solar cells (PSCs). Herein, we report a novel molecular concept of a <i>C</i>₂-symmetric <i>syn</i>-type bifacial donor-π-donor (D-π-D) passivation molecule (a racemic mixture of enantiomers) with hydrophobic phenyls and hydrophilic tetraethylene glycol-substituted phenyls on each face of the indeno-[1,2-<i>b</i>]fluorene π-core. In addition to this bifacial amphiphilic π-co

The chemical structure of a branch point of star-shaped polymers has been considered to have a small influence on the physical properties of the entire polymer. Contrary to this general notion, here we show that a 3-arm star polymer, composed of three poly(δ-valerolactone) arms extended from one side of a triptycene branch point, exhibits a remarkably high complex viscosity, compared to the analogous star-shaped polymers with a branch point of a triptycene isomer or triphenylethane.