Jun Terao

The University of Tokyo | Todai

Structural switching of [3]catenane was induced by fitting the puzzle pieces. In their Research Article (DOI: 10.1002/anie.202217002), Jun Terao et al. report a method for ligand‐controlled structural switching of [3]catenane, which was realized by the complexation of metal ions on [3]catenane with added complementarily fitted organic ligands, like...

Structural switching of [3]catenane was induced by fitting the puzzle pieces. In their Research Article (DOI: 10.1002/ange.202217002), Jun Terao et al. report a method for ligand‐controlled structural switching of [3]catenane, which was realized by the complexation of metal ions on [3]catenane with added complementarily fitted organic ligands, like...

Catenanes with multistate switchable properties are promising components for next‐generation molecular machines and supramolecular materials. Herein, we report a ligand‐controlled switching method, a novel method for the multistate switching of catenanes controlled by complexation with added amine ligands. To verify this method, a [3]catenane compr...

Catenanes with multistate switchable properties are promising components for next‐generation molecular machines and supramolecular materials. Herein, we report a ligand‐controlled switching method, a novel method for the multistate switching of catenanes controlled by complexation with added amine ligands. To verify this method, a [3]catenane compr...

A new synthetic strategy for macrocycles bearing multiple coordination moieties was developed. A self-assembled double helix structure, composed of two linear strands bearing 2,2'-bipyridine units and Cu(I) ions, provided access to macrocycles bearing a defined number of 2,2'-bipyridine moieties and a defined ring size, via an olefin-metathesis rea...

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...

A coumarin derivative bearing a [1]rotaxane structure with permethylated -cyclodextrins suppressed unwanted solvation-induced effects and increased luminescent quantum yields in medium- and high-polarity solvents. The non-radiative decay was suppressed by...

In this work, a real‐time precise electrical method to directly monitor the stochastic binding dynamics of a single supramolecule based on the host‐guest interaction between a cyclodextrin and an azo compound is reported. Different intermolecular binding states during the binding process are distinguished by conductance signals detected from graphe...

The high surface sensitivity of low-dimensional carbon nanomaterials renders them good candidates for noise detection. Herein, Mg-porphyrin-modified graphene field-effect transistors (FETs) were fabricated, and parts-per-billion concentrations of NO 2 were introduced to the devices. When the power spectrum density (PSD) of the Mg-porphyrin-modified...

The characterization of single-molecule structures could provide significant insights into the operation mechanisms of functional devices. Structural transformation via isomerization has been extensively employed to implement device functionalities. Although single-molecule identification has recently been achieved using near-field spectroscopy, di...

The restriction of local molecular motions is critical for improving the fluorescence quantum yields (FQYs) and the photostability of fluorescent dyes. Herein, we report a supramolecular approach to enhance the performance of fluorescent dyes by incorporating a linked rotaxane structure with permethylated α-cyclodextrins. Tetraphenylethylene (TPE)...

The Migita-Kosugi-Stille coupling reaction is a powerful method for the formation of carboncarbon bonds but often requires high temperatures that are not tolerated by all substrates. Herein, we report that irradiation with UV light accelerates this coupling reaction at room temperature in air in the presence of the commercially available PdCl2(PPh3...

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 atten...

The trace detection of NO2 through small sensors is essential for air quality measurement and the health field; however, small sensors based on electrical devices cannot detect NO2 with the desired selectivity and quantitativity in the parts per billion (ppb) concentration region. In this study, we fabricated metalloporphyrin-modified graphene fiel...

π-Conjugated molecules have been utilized to functionalize inorganic surfaces to form organic–inorganic hybrid materials. However, the intrinsically strong π–π interaction results in undesirable aggregations on the inorganic surface, thereby disturbing the charge transfer through the organic–inorganic interface. In this study, a new strategy was de...

Click reactions (e.g., Huisgen cycloaddition) on metal oxide nanostructures offer a versatile and robust surface molecular modification for various applications because they form strong covalent bonds in a wide range of molecular substrates. This study reports a rational strategy to maximize the conversion rate of surface click reactions on single-...

Seeded crystal growths of nanostructures within confined spaces offer an interesting approach to design chemical reaction spaces with tailored inner surface properties. However, such crystal growth within confined spaces tends to be inherently difficult as the length increases as a result of confinement effects. Here, we demonstrate a space-confine...

One of the ultimate goals of analytic chemistry is to efficiently discriminate between amino acids. Here we demonstrate this ability using a single-molecule electrical methodology based on molecular nanocircuits formed from stable graphene-molecule-graphene single-molecule junctions. These molecular junctions are fabricated by covalently bonding a...

Herein, we report the kinetics of pseudo[1]rotaxane formation from permethyl α-cyclodextrin attached to a flexible-chain-substituted diphenylethynylene. When the chain is an alkyl group, the rate of formation shows different trends over three regions of chain length: deceleration (chain length = 1–3), acceleration (4–8), and re-deceleration (> 12)....

For luminescent materials, the isomerization and intermolecular reactions of their double bonds are often undesirable because they cause a reduction in the luminescence properties of the p‐system. Herein, we report a new methodology to simultaneously prevent isomerization and intermolecular reactions by utilizing the steric effect of a linked rotax...

The electrical properties of a single-molecule junction of spiropyran are investigated through the break junction (BJ) method, and the current-voltage (I-V) characteristics are switched from rectified to symmetric through mechanical...

Phosphorescence colors of cyclodextrin-based insulated Pt–acetylide complexes were tuned by molecular engineering of the chromophores. A series of Pt-complexes bearing various acetylide ligands, including heteroaromatics, was prepared via self-inclusion of the linked-macrocycles with the complexes. The decline in inclusion efficiency derived from t...

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 a...

An insulated metallopolymer that undergoes phosphorescence-to-fluorescence conversion between complementary colors by an acid-stimulus is proposed as a color-tunable material. A Pt-based phosphorescent metallopolymer, where the conjugated polymeric backbone is insulated by a cyclodextrin, is depolymerized by HCl via acidic cleavage of Pt-acetylide...

In article number 1900464 by Jun Terao, Jinlong Yang, Xuefeng Guo, and co‐workers, charge‐ and temperature‐dependent movement dynamics and mechanism of molecular machines at the single‐event level are revealed by using stable graphene‐molecule‐graphene single–molecule junctions. These investigations conceptualize the capability of single‐molecule e...

Systematic investigation of rotaxane structures revealed a rational design for thermally driven switching of their macroscopic properties. At low temperature, the luminophore is insulated by a cyclic molecule and displays monomer emission, while at high temperature, the luminophore is exposed due to a change in the macrocyclic location distribution...

An insulated Pt-acetylide complex was incorporated into a polymer network as a crosslinker to afford a hydrogel. Because of the insulation effect, the formed hydrogel exhibited strong phosphorescence and enhanced...

Single‐molecule detection is able to reveal rich spatial/temporal information and elucidate intrinsic mechanisms of inter or intramolecular interactions that are not accessible in ensemble experiments, which is of fundamental importance to solve the key issues in physical, chemical, and biological sciences. Here, a robust, label‐free single‐molecul...

π-Conjugated porphyrin-containing hollow structures with defined axis-length were successfully synthesized by a two-step template method, i.e., template-assisted cyclization and oligomerization. During the oligomerization, templates played important roles in controlling the...

A π-conjugated polymer containing spiropyrans (SPs), which could be almost completely converted to protonated merocyanines (MCH+) and back to the SP form by adding an acid and a base, respectively, was developed. The insulation of the π-conjugated polymer, referred to as insulated spiropyran-containing poly(p-phenylene ethynylene) (ins-SP-PPE), usi...

Metal oxide nanowires have demonstrated excellent capability in the electrical detection of various molecules, based on their material robustness in liquid and air environments. Although the surface structure of the nanowires essentially determines their interaction with adsorbed molecules, understanding the correlation between an oxide nanowire su...

An oxygen-sensitive gel material containing platinum-acetylide was successfully synthesized using covalent linkages between the isocyanate groups on the platinum-acetylide crosslinker and the hydroxyl groups on commodity polymers. It was shown that the elasticity of the gel could be tailored by changing the amount of the crosslinker. Under nitrogen...

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 res...

Unidirectional insulated molecular wires (IMWs) were precisely synthesized via iterative cross‐coupling reactions in organic solvents and subsequent intramolecular slippage transformation in aqueous solvents. This programmable synthetic procedure selectively afforded both insulated and uninsulated molecular wires bearing oligo (phenylene ethynylene...

Copper–catalyzed [4+2] cycloaddition of N‐(2‐pyridyl)ketimines and terminal alkynes has been achieved. Ketimines bearing a trifluoromethyl group reacted with various terminal alkynes to produce pyrido[1,2‐a]pyrimidines in good to high yields. This reaction proceeded through a propargylamine intermediate and the corresponding product was obtained vi...

A three-dimensionally insulated Pt(II) bis(dithiobenzoate) complex with a [1]rotaxane structure was synthesized using permethylated cyclodextrins. We have confirmed macrocyclic insulation is necessary to yield the Pt(II) bis(dithiobenzoate) complex with high selectivity. Furthermore, the formed Pt(II) complex showed highly stable and reversible two...

Herein, we describe the synthesis of a Ni(II) bis(dithiobenzoate)-type complex three-dimensionally insulated by a [1]rotaxane structure, revealing the importance of ligand insulation. Under cyclic voltammetry conditions, the complex showed stable...

Carboxylic acids 1a and 1b bearing three poly(ethylene glycol) (PEG) chains and carboxylic acid 1c bearing one PEG chain were designed and synthesized. The carboxylic acids 1a–c were fully characterized by NMR and ESI-HRMS analyses. In a Pd-catalyzed aerobic oxidation of 1-phenylethanol, 1a and 1b worked well as carboxylate ligands.

Insertion of interfacial molecules in bulk heterojunction and dye sensitized solar cells is effective to retard charge recombination reactions, and thus to improve solar cell performance. So far, to extend charge separated state lifetime, the molecule was designed to increase distance between an n-type and a p-type semiconductors to reduce their el...

Diverse functionalized insulated conjugated polymers (ICPs) were synthesized via co-polymerization between insulated conjugated monomers and various functional units. Such polymers possessed well-defined, linked-rotaxane structures with target-specific insulations through a fine-synthetic technique. The functional moieties on the polymer backbones...

Mother and child play toy trains, they freely arrange the sequences of containers. This image describes a new synthetic method of insulated molecular wires with strictly defined axle lengths and macrocyclic covering positions/degrees. A completely insulated molecular wire (up to a linked-[11]rotaxane) was afforded through an iterative synthetic tec...

A new method for the synthesis of an insulated π-conjugated molecule as a powerful building block for the construction of a insulated molecular wire (IMW) was developed via the sequential self-inclusion of π-conjugated guest-branched permethylated α-cyclodextrin followed by the elongation of the π-conjugated unit. Covering a single π-conjugated wi...

Magnesium chloride (MgCl2), a stable and cheap salt, works as an active catalyst for the synthesis of cyclic carbonates from epoxides and atmospheric-pressure carbon dioxide (CO2). Various epoxides are converted to the corresponding cyclic carbonates in good to high yields.

The development of new tuning methods for π-conjugated insulated molecular wires with strictly defined axle lengths and macrocyclic covering positions/degrees, would provide unprecedented insight into insulation effects in functionalized materials. Herein, iterative reactions of oligo(phenylene ethynylene) (OPE) linked with permethylated α-cyclodex...

We successfully synthesized a hetero face-to-face porphyrin array composed of ZnTPP and RuTPP(DABCO)₂ (TPP: 5,10,15,20-tetraphenylporphyrin, DABCO: 1,4-diazabi-cyclo[2.2.2]octane) in 2:1 molar ratio. A cyclic Zn porphyrin dimer (ZnCP) was also used as the host molecule for the Ru porphyrin. In the latter, the Ru-DABCO bonding in RuTPP(DABCO)₂ was s...

Buy Article Permissions and Reprints Abstract Macrocyclic dinuclear complexes have been gaining popularity in the design of homogeneous catalysts. Herein, we report the design of such a complex featuring catalytically active sites fixed inside the ring and its synthesis using a cross-coupling reaction. Keywords macrocycle - N-heterocyclic carbene...

The hydroallylation of allenes is developed employing a hydrosilanes and allyl chlorides in the presence of a copper catalyst. The reactions provided (E)-1,5-dienes mainly in good to high yields.

Triarylalkene-capped conjugated rotaxanes were synthesized via a palladium-catalyzed tandem Sonogashira/hydroaryl reaction between aryl halides and terminal alkynes bearing two permethylated α-cyclodextrins (PM α-CDs) with high regioselectivity because of the insulation effect of the PM α-CDs. Moreover, sequential Sonogashira coupling and hydroaryl...

Kupfer …… wird für die Legierung der japanischen 10-Yen-Münze, auf der der Byodo-in-Tempel zu sehen ist, verwendet und ist ein effizienter Katalysator der Boraformylierungen und Silaformylierungen von Allenen mit Formiatestern, die T. Fujihara, Y. Tsuji et al. in der Zuschrift auf S. 1561 ff. beschreiben. In Gegenwart von B2(pin)2 oder PhMe2SiB(pin...

Copper is a raw material for the Japanese 10 Yen coin, on which the Byodo-in Temple is shown, and an efficient catalyst for the boraformylation and silaformylation reactions of allenes with formate esters that are reported by T. Fujihara, Y. Tsuji, and co-workers in their Communication on page 1539 ff. With B2(pin)2 or PhMe2Si−B(pin), these reactio...

The boraformylation of allenes with B2(pin)2 and a formate ester as boron and formyl source, respectively, proceeds in the presence of a copper catalyst. The reaction selectively affords the corresponding β-boryl β,γ-unsaturated aldehydes in good to high yields. Furthermore, the silaformylation of allenes was achieved with a formate ester and PhMe2...

The boraformylation of allenes with B2(pin)2 and a formate ester as boron and formyl source, respectively, proceeds in the presence of a copper catalyst. The reaction selectively affords the corresponding β‐boryl β,γ‐unsaturated aldehydes in good to high yields. Furthermore, the silaformylation of allenes was achieved with a formate ester and PhMe2...

We used first-principles calculations to investigate the hole mobility of metal-containing poly(phenylene ethynylene) insulated molecular wires. The metal–organic bond effects were considered using ruthenium(II) porphyrin–pyridyl and platinum(II) acetylide as the organometallic moieties. We found that high hole mobility can be achieved even when th...

A chameleon polymer could be color-tuned easily, directly, and reversibly by metal coordination without changes to the main-chain skeleton. In their Communication (DOI: 10.1002/anie.201603160), J. Terao et al. describe the efficient emission of the metalated polymer which is due to the permethylated α-cyclodextrin-based insulation structure of the...

Ein Chamäleonpolymer konnte einfach, direkt und reversibel durch Metallkoordination farblich modifiziert werden, ohne dass es zu Änderungen am Hauptkettengerüst kam. In ihrer Zuschrift (DOI: 10.1002/ange.201603160) beschreiben J. Terao et al. die effiziente Emission des metallierten Polymers aufgrund der Isolation des Chamäleonpolymers durch die pe...

Regio- and stereoselective carboxyzincation reactions of alkynes provide (Z)-?-zincated acrylates.

We report the synthesis of an insulated π-conjugated polymer containing 2,2'-bipyridine moieties as metal coordination sites. Metal coordination to the polymer enabled easy and reversible tuning of the luminescent color without changes to the main chain skeleton. The permethylated α-cyclodextrin (PM α-CD)-based insulation structure allowed the meta...

We report the synthesis of an insulated π-conjugated polymer containing 2,2′-bipyridine moieties as metal coordination sites. Metal coordination to the polymer enabled easy and reversible tuning of the luminescent color without changes to the main chain skeleton. The permethylated α-cyclodextrin (PM α-CD)-based insulation structure allowed the meta...

Various carboxylic acids with different substitution patterns were used as ligands in intra- and intermolecular Pd-catalyzed C–H activation reactions to investigate steric effect of the ligands. Bulky carboxylic acids suppress deactivation of Pd catalysts.

Insulated conductive molecules, in which the π-conjugated compounds are covered by a cyclic protective sheath, have attracted considerable attention because of their potential applicability in next-generation molecular electronic devices. New methods of synthesizing three-dimensionally insulated π-conjugated molecules through the polymerization of...

A bridging monomer with terpyridine moieties on both ends of the insulated conjugated chain was successfully synthesized. The synthesis necessitated a new synthetic strategy, in which FeII was employed as a removable water-solubilizing substituent. The monomer was able to coordinate with FeII, CoII, NiII, or RuII to give highly insulated conjugated...

Cobalt-catalyzed carboxyzincation reactions employing carbon dioxide (CO2) and Zn metal powder are developed. By using alkynes as substrates, regio- and stereodefined (Z)-β-zincated acrylates are provided. The corresponding alkenylzinc moiety can be converted to various substituents affording multi-substituted acrylic acids. Furthermore, by adding...

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 ac...

A highly efficient cobalt-catalyzed reductive carboxylation reaction of alkenyl trifluoromethanesulfonates (triflates) has been developed. Employing Mn powder as a reducing reagent under 1 atm pressure of CO2 at room temperature, diverse alkenyl triflates can be converted to the corresponding alpha,beta-unsaturated carboxylic acids. Moreover, the c...

N-Heterocyclic carbenes bearing poly(ethylene glycol) chains of different lengths have been designed and employed as ligands in palladium-catalyzed coupling reactions. The catalyst system having longer chains was found to be highly efficient for Suzuki-Miyaura coupling and borylation reactions employing aryl chlorides under mild reaction conditions...

Insulated conductive molecules, in which the g-conjugated compounds are covered by a cyclic protective sheath, have attracted considerable attention because of their potential applicability in next-generation molecular electronic devices. We have developed new methods of synthesizing insulated pi-conjugated molecules involving the self-inclusion of...

In this study, pi-conjugated molecular wires strapped by cyclic pi-conjugated side chains were efficiently synthesized by the integration of dehydrobenzo[20]annulene units by intramolecular Glaser-type cyclization under high dilution conditions.

Electromechanical properties of single molecular junctions are investigated using scanning tunneling microscopy based break junction method. Two types of molecular junctions consisting of π-conjugated backbones with and without coordinative bonding (i.e., Co((4-aniline)-terpyridine)2 complex and oligo(phenylene-ethynylene) derivative) are prepared...

A highly selective carbon–carbon bond-forming transformation of carbon dioxide (CO2) to the alcohol oxidation level has been disclosed. By employing a copper/bisphosphine catalyst system and hydrosilanes as the mild and easy-to-handle reducing agents, various allenes react with CO2 to give homoallylic alcohols regioselectively. Esters and other red...

The copper-catalyzed silylative allylation of ketones with allenes and silylboranes via an in situ generated β-silylallylcopper intermediate has been developed. Various ketones and allenes were converted to the homoallylic tertiary alcohols bearing internal (E)-vinylsilane moieties regio- and stereoselectively in good to high yields. Aldehydes were...

Copper-catalyzed borylative transformations of non-polar carbon-carbon unsaturated compounds using borylcopper as an active catalyst species are described in this review. First, the importance of developing synthetic methods for preparation of organoboronic acids and their derivatives in modern organic synthesis is addressed and the background of t...

The formal hydroacylation reaction of allenes has been developed employing carboxylic anhydrides as acyl sources and hydrosilanes as reducing reagents in the presence of a commercially available palladium complex as a catalyst. The reaction affords α,β-unsaturated ketones regio- and stereoselectively. The similar catalyst system is also effective f...

The regiodivergent silacarboxylation of allenes is developed under carbon dioxide atmosphere with PhMe2Si-B(pin) as a silicon source in the presence of a copper catalyst at 70 °C. The regioselectivity of the reaction is successfully reversed by the proper choice of ligand; carbox-ylated vinylsilanes are obtained with rac-Me-DuPhos as the ligand, wh...

A new method for the synthesis of an insulated π-conjugated molecule was developed via the sequential self-inclusion of π-conjugated guest branched permethylated α-cyclodextrin followed by the elongation of the π-conjugated unit. Covering a single π-conjugated wire by an α-cyclodextrin derivatives can suppress conductance fluctuation. The insulated...

We synthesized symmetrically insulated oligo(para-phenylene) and oligothiophene with a pseudo-linked [3]rotaxane structure by full rotation of glucopyranose units via a flipping (tumbling) mechanism in the π-conjugated guest having two permethylated β-cyclodextrin units at both ends. We also succeeded in the synthesis of an organic-soluble fixed [3...

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 ar...

The nickel-catalyzed double carboxylation of internal alkynes employing carbon dioxide (CO2) has been developed. The reactions proceed under CO2 (1 atm) at room temperature in the presence of a nickel catalyst, Zn powder as a reducing reagent, and MgBr2 as an indispensable additive. Various internal alkynes could be converted to the corresponding m...

Borylative allyl–allyl coupling using allenes, bis(pinacolato)diboron, and allyl phosphates has been developed in the presence of a copper catalyst bearing an N-heterocyclic carbene ligand. The reaction affords boryl-substituted 1,5-diene derivatives in good to high yields with high regioselectivity and Z selectivity.

Borylative allyl-allyl coupling using allenes, bis(pinacolato)diboron, and allyl phosphates has been developed in the presence of a copper catalyst bearing an N-heterocyclic carbene ligand. The reaction affords boryl-substituted 1,5-diene derivatives in good to high yields with high regioselectivity and Z selectivity.

A new type of molecular wiring method was developed based on the polymerization or copolymerization of an insulated pi-conjugated monomer between nanosized electrodes.