Co-reporter:Yusuke Satta, Ryuhei Nishiyabu, Tony D. James, Yuji Kubo
Tetrahedron 2017 Volume 73, Issue 15(Issue 15) pp:
Publication Date(Web):13 April 2017
DOI:10.1016/j.tet.2017.02.050
Our interest in the functionalization of OH-substituted azaborines prompted us to synthesize a 1-hydroxy-2,3,1-benzodiazaborine conjugated with 1,8-naphthalimide 1. Its fluorescence was dramatically affected by the nature of the solvent. In particular, the use of DMSO, which has a relatively high donor number (DN = 29.8), led to a remarkable decrease in the fluorescence intensity (ΦF = 0.0014), possibly due to intermolecular hydrogen-bonding interactions (Me2SO⋯HOB). The presence of the hydroxyl group on boron led to a solvent-driven colorimetric response towards anions; high selectivity for F− over other anions in DMSO, and responded to AcO− and F− in THF, as shown by UV/vis titrations, NMR, and mass spectroscopic analysis. The nucleus-independent chemical shift (NICS) indices suggested that hydrogen bonding interactions between Me2SO and HOB reduced the aromaticity of the benzodiazaborine macrocycle, causing an increase in the negative character of the boron. The increase in the polarity of the BN bond may prevent acetate-binding of 1 in DMSO.Download high-res image (156KB)Download full-size image
Co-reporter:Meiko Kawai;Ayaka Hoshi;Ryuhei Nishiyabu
Chemical Communications 2017 vol. 53(Issue 73) pp:10144-10147
Publication Date(Web):2017/09/12
DOI:10.1039/C7CC05784A
Chiral ensembles were spontaneously formed in solution through boronate esterification of structurally defined di(boronic acid)-appended tetraphenylethylene (DB-TPE) and commercially available L- or D-tartaric acid, showing enantioselective aggregation behavior for chiral diamines as well as cinchona alkaloids enabling the fluorescent recognition of their chirality.
Co-reporter:Okta Suryani;Yuta Higashino;Jacob Yan Mulyana;Masayoshi Kaneko;Takayuki Hoshi;Koichiro Shigaki
Chemical Communications 2017 vol. 53(Issue 50) pp:6784-6787
Publication Date(Web):2017/06/20
DOI:10.1039/C7CC02730C
Dye-sensitized photoelectrochemical cells (DSPECs) composed of a new near-infrared BODIPY dye D1 that is co-deposited with a ruthenium water oxidation catalyst C1 have been fabricated. The devices at pH 7.2 showed an excellent Faradaic efficiency of H2 production (65.8%) that was 5.4 times larger than that of a triphenylamine photosensitizer D2 and C1-coadsorbed cell.
Co-reporter:Kaori Sakakibara;Yuki Takahashi;Ryuhei Nishiyabu
Journal of Materials Chemistry C 2017 vol. 5(Issue 15) pp:3684-3691
Publication Date(Web):2017/04/13
DOI:10.1039/C7TC00405B
Driven by our motivation to develop a chemodosimeter for the visual detection of hydrogen peroxide (H2O2), we synthesized for the first time a dipyrrin (1) with 4-pinacolborylbenzyloxy groups. An EtOH solution of Zn2+-coordinated 1 was reddish-violet in color, with a λmax value of 538 nm. However, the addition of H2O2 into the solution induced a remarkable color change from reddish-violet to blue. The time-dependent change in the absorption band showed two step kinetic processes in their kinetic profiles, where a new peak with λmax = 581 nm appeared within 13 min (k1 = 0.370 min−1), followed by a slower change in the spectra (k2 = 0.00371 min−1) concomitant with a further bathochromic shift of 18 nm. NMR and mass spectroscopic analyses indicated that the kinetically slower process may be responsible for a change in the coordination mode of the Zn2+ ion through a H2O2-triggered self-immolative reaction in the 4-pinacolborylbenzyloxy groups. Basic conditions achieved through the addition of tetrabutylammonium hydroxide (TBAOH) led to the acceleration of not only the H2O2-triggered colorimetric change but also the turn-on fluorescence, thus allowing dual-mode sensing of H2O2. For practical applications, the related drop-cast paper strips were fabricated to visually detect H2O2 vapor.
Co-reporter:Sule Erten-Ela;Yoshihide Ueno;Takuro Asaba
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 18) pp:10367-10375
Publication Date(Web):2017/09/11
DOI:10.1039/C7NJ01735A
For the application of metal-free organic sensitizers in dye-sensitized solar cells (DSSCs), a boron dibenzopyrromethene (dibenzo-BODIPY)-conjugated phenothiazine dye with cyanoacrylic acid as an anchoring group 1 was synthesized and characterized. It showed an intense absorption band at 638 nm as the λmax value and a molar extinction coefficient (ε) of 1.23 × 105 M−1 cm−1. In addition, a relatively small but significant peak was observed at 440 nm (ε = 1.80 × 104 M−1 cm−1). Such panchromatic features allowed the fabrication of a DSSC with an excellent short-circuit current density (Jsc) of 19.09 mA cm−2 under 100 mW cm−2 AM1.5G simulated light. The corresponding external quantum efficiency (EQE) indicated that the cell converted the light to a photocurrent in a wide wavelength region up to 780 nm, resulting in a power conversion efficiency (PCE; η) of 7.69% in an I−/I3− redox couple electrolyte without the addition of any coadsorbents. When compared to the control cell loaded with a cycanoacrylic acid-appended phenothiazine 2, the PCE value of the 1-loaded cell was 1.5 times larger than that of the control cell because of significant enhancements in both Jsc and open-circuit voltage (Voc). Electrochemical impedance analysis (EIS) suggested attenuation of the charge recombination when using 1 as a sensitizer. In this way, the 1-loaded cell showed relatively good DSSC properties comparable to those of the cell with N719 (η = 7.15%) under the same conditions.
Co-reporter:Yuji Kubo, Ryuhei Nishiyabu
Polymer 2017 Volume 128(Volume 128) pp:
Publication Date(Web):16 October 2017
DOI:10.1016/j.polymer.2016.12.082
•Polymer-based materials with white-light emission have emerged as fascinating materials.•White luminescence is composed of comparative intensities of light throughout the whole visible region.•Supramolecular polymerization can tune the amount of color-emissive components in systems.•Dynamic covalent bond-based polymers are also suitable for the preparation of white-light emissive materials.•This review describes white-light emissive materials using a rational approach based on dynamic polymerization.Polymer-based materials with white-light emission have attracted much attention because of their potential applications as organic light-emitting diodes (OLEDs) and bright sensor materials. Synthesizing one polymer to cover the entire region of visible light is not easy. In addition, facile mixing of multiple kinds of emissive polymers can cause unfavorable interactions between them, making it difficult for chemists to prepare materials with this type of emission. Recently, much effort has been devoted to proposing efficient strategies toward this end, which involve multilayer systems with blends of different color-emitting polymers, single-layer polymer blends, and polymer hosts doped with fluorescent or phosphorescent dyes. By fine tuning the primary colors, i.e., red, green, and blue, or two complementary colors, e.g., cyan and orange, supramolecular polymerization can create one-dimensional assemblies with dynamic and reversible non-covalent bonds, such as hydrogen bonds, metal coordination, electrostatic interactions, hydrophobic interactions, and π‒π stacking interactions. Such adaptive and alterable features could control the amount of color-emissive components in systems where the management of energy transfer is possible. Furthermore, orthogonal polymerization provides well-defined three-dimensional assemblies. In this context, dynamic covalent bond-based polymers are also suitable to create white-light emissive materials that are relevant to supramolecular polymers. This review describes the preparation of white-light emissive materials using a rational approach based on dynamic polymerization in supramolecular chemistry.Download high-res image (113KB)Download full-size image
Co-reporter:Tsuyoshi Minami, Fereshteh Emami, Ryuhei Nishiyabu, Yuji Kubo and Pavel Anzenbacher
Chemical Communications 2016 vol. 52(Issue 50) pp:7838-7841
Publication Date(Web):16 May 2016
DOI:10.1039/C6CC02923J
Self-assembled colorimetric sensors have been prepared from ZnII–DPA-attached phenylboronic acid (1·Zn) and catechol-type dyes. The 1·Zn–dye sensors display selectivity towards oligophosphate over monophosphates. The colorimetric sensor assay (1·Zn–dye) is utilized to monitor a model of a metabolic reaction where ATP is hydrolyzed to pyrophosphate (PPi) and AMP.
Co-reporter:Sho Yamazawa, Mika Nakashima, Yukie Suda, Ryuhei Nishiyabu, and Yuji Kubo
The Journal of Organic Chemistry 2016 Volume 81(Issue 3) pp:1310-1315
Publication Date(Web):January 6, 2016
DOI:10.1021/acs.joc.5b02720
2,3-Naphtho-fused boron-dipyrromethenes (BODIPYs) 1a and 1b, which absorb near-infrared light at 740–770 nm with molar extinction coefficients above 105 M–1 cm–1 in THF, have been synthesized through a palladium(II)-catalyzed direct acylation of N-BOC hydrazones and subsequent Paal–Knorr pyrrole synthesis. Simple benzo-annulation of dibenzo-BODIPY caused a significant red-shift in the absorption. Subsequent intramolecular B,O-cyclization of 1b gave 2, which exhibited an intense absorption band at 830 nm. The structure–optical property relationship has been investigated using theoretical calculations and cyclic voltammetry.
Co-reporter:Ayumi Ozawa, Ai Shimizu, Ryuhei Nishiyabu and Yuji Kubo
Chemical Communications 2015 vol. 51(Issue 1) pp:118-121
Publication Date(Web):03 Nov 2014
DOI:10.1039/C4CC07405J
Boronate nanoparticles with built-in tetraphenylethylene (TPE) have been prepared. Their emissive color tuning by altering the amount of rhodamine B grafted onto the surface gave white-light emissive nanoparticles. They showed reversible and thermo-responsive emission in the temperature range of 5–65 °C in water, which enabled them to serve as a bright nanothermometer.
Co-reporter:Yuji Kubo, Ryuhei Nishiyabu and Tony D. James
Chemical Communications 2015 vol. 51(Issue 11) pp:2005-2020
Publication Date(Web):24 Nov 2014
DOI:10.1039/C4CC07712A
Current progress on hierarchical supramolecules using boronic acids has been highlighted in this feature article. Boronic acids can participate in “click reactions” with diols and their congeners with dynamic covalent functionality. By comprehensively exploring versatile sequential boronate esterification linkages between plural boronic acid-appended molecules and multiple hydroxyl counterparts, not only versatile supramolecular polymers but also structurally well-defined network nanostructures have been developed. In addition orthogonal interactions such as dative bonds of the boron center with Lewis bases have led to the formation of hierarchical nano/microstructures. Boronate systems have the potential to be used as materials for smart gels, chemosensors, active architectures for electronics, heterogeneous catalysts, chemical-stimulus responsive systems for drug delivery, etc. Here, we fully discuss the feasibility of the structure-directing ability of boronic acids from the standpoint of the generation of new smart materials.
Co-reporter:Seika Fujiwara, Naoto Takanashi, Ryuhei Nishiyabu and Yuji Kubo
Green Chemistry 2014 vol. 16(Issue 6) pp:3230-3236
Publication Date(Web):17 Apr 2014
DOI:10.1039/C4GC00383G
Dispersible self-assembled boronate polymers can serve as support materials for metal nanoparticle catalysts. As a proof-of-concept, catalytic systems for the chemoselective hydrogenation of cinnamaldehyde (CA) were prepared by the NaBH4 reduction of PdCl42− and AuCl4− in methanol, in the presence of polyethyleneimine (PEI)-coated boronate particles (BPs) composed of polymeric 3-benzo-2,4,8,10-tetraoxa-3,9-diboraspiro[5.5]undecane. The Pd-deposited BP (Pd/BP) showed highly selective catalytic activity for the hydrogenation of CA to hydrocinnamaldehyde (HCA) under 0.1 MPa of H2 at 25 °C in environmentally preferable solvents such as water and methanol. Of particular note is the recyclability of the hydrogenation catalyst in methanol; repeated 4 h reactions afforded HCA in >90% selectivity with a reaction conversion of 100%. On another front, when the corresponding Au catalyst (Au/BP) was used in the hydrogenation in water, a favorable selective reduction of CO to cinnamyl alcohol (CAL) (selectivity ≈ 80%) was obtained with 78% reaction conversion under 0.8 MPa of H2 at 80 °C for 12 h. The potential use of BP-supported metal nanoparticles as green catalysts is discussed.
Co-reporter:Ryuhei Nishiyabu, Shiho Ushikubo, Yuka Kamiya and Yuji Kubo
Journal of Materials Chemistry A 2014 vol. 2(Issue 38) pp:15846-15852
Publication Date(Web):30 Jul 2014
DOI:10.1039/C4TA03268C
A multicolor fluorescent hydrogel sensor containing two types of fluorescent dyes with an amidoquinoline receptor unit and a rhodamine chromophore covalently incorporated into a polyvinyl alcohol–boronate matrix was prepared. Although the gel film exhibited red emission due to the rhodamine chromophore, the addition of a small amount of Zn2+ ions induced a multicolor fluorescence response, which included white-light emission, of the film in water. The change in emission color is ascribed to fluorescence enhancement of the amidoquinoline moiety upon binding to Zn2+ ions with an association constant of (3.5 ± 0.2) × 105 M−1. In contrast, a negligible change in the emission color of the gel film was observed in the presence of Na+, K+, Mg2+, Ca2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Hg2+, Al3+, and Pb2+ ions. The selectivity of the gel film enabled visual detection of Zn2+ ions in tap water. Moreover, the film could be reused as a sensor strip after treatment with ethylenediaminetetraacetic acid.
Co-reporter:Yuji Kubo, Daichi Eguchi, Asaki Matsumoto, Ryuhei Nishiyabu, Hidenori Yakushiji, Koichiro Shigaki and Masayoshi Kaneko
Journal of Materials Chemistry A 2014 vol. 2(Issue 15) pp:5204-5211
Publication Date(Web):24 Jan 2014
DOI:10.1039/C3TA15340A
Novel boron–dibenzopyrromethene dyes with thienyl-cyanoacrylic acid units were synthesized and characterized for application in dye-sensitized solar cells (DSSCs); the dyes feature intense absorption bands in the longer wavelength region with λmax values of 647 nm (ε = 1.57 × 105 M−1 cm−1) for 1, which has two anchoring units, 660 nm (ε = 1.09 × 105 M−1 cm−1) for regioisomer 2, and 644 nm (ε = 1.39 × 105 M−1 cm−1) for 3, which has a single anchoring unit. Density functional theory (DFT) analysis revealed that these absorption properties are mainly characterized by intramolecular charge transfer from the dibenzopyrromethene core to the thienyl-cyanoacrylic acid unit that depend on both the number of anchoring groups and the position of the thienyl-cyanoacrylic acid unit on the isoindole ring. The relationship between the chemical structures and cell properties of these dyes was investigated. Although the short circuit photocurrent density (Jsc) value of a 1-loaded cell is larger than that of a 3-loaded cell, which reflects the results of the incident photon-to-charge carrier efficiency (IPCE) spectra, the 1-loaded cell has a lower open circuit voltage (Voc) and fill factor (FF). Accordingly, overall power-to-current conversion efficiencies of 5.24 and 5.48% were obtained for a 1-loaded cell and 3-loaded cell, respectively, under 100 mW cm−2 AM1.5G simulated light. On the other hand, the cell containing butterfly-shaped regioisomer 2, which showed improved intramolecular charge transfer, has an overall power-to-current conversion efficiency of 6.06%; this value is the highest published for BODIPY dyes even though the sensitizer does not contain any strong donor units, such as arylamines.
Co-reporter:Asaki Matsumoto, Ryuhei Nishiyabu and Yuji Kubo
RSC Advances 2014 vol. 4(Issue 72) pp:37973-37978
Publication Date(Web):13 Aug 2014
DOI:10.1039/C4RA06061J
Given our interest in the development of reaction-based chemosensors, we developed a novel boron–dibenzopyrromethene dye with a pinacolboryl group (1), blue in color (λmax = 621 nm, ε = 8.74 × 104 M−1 cm−1) with red emission (λmax = 643 nm, λex = 550 nm) in THF. H2O2-mediated oxidation of the pinacolboryl group was found to induce a significant fluorescence decrease at 642 nm (λex = 550 nm) in EtOH/H2O (1:1 v/v) at 25 °C, enabling us to detect trace levels of H2O2 visually. The time-dependent response was investigated to evaluate the pseudo-first-order rate constant of 1.69 min−1 under basic conditions, meaning that its fluorescence was decreased by 80% in 2 min. Such a remarkable response capability motivated us to test the suitability of 1 for the detection of H2O2 vapor. For these experiments, a 1-coated TLC plate was fabricated by a spin-coating method and then placed in sealed bottles with H2O2 vapor. It was found that the increasing vapor concentration of H2O2 could be visually monitored by a change in red emission (ΔR value). Based on this, we estimated the detection limit of this method to be 8.43 ppb. We also found that the 1-coated TLC plate could selectively detect H2O2 vapor over common solvents tested.
Co-reporter:Ryuhei Nishiyabu, Yasuyuki Sugino and Yuji Kubo
Chemical Communications 2013 vol. 49(Issue 84) pp:9869-9871
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3CC45739G
The facile surface functionalization of surfactant-free organic microparticles composed of polymeric 2,4,8,10-tetraoxa-3,9-diboraspiro[5.5]undecane allowed us to develop white-light emissive chemosensors for the real-time visual detection of Cu2+ in HEPES buffer (pH 7.0) due to a synergistic response of fluorophores grafted onto the particles. A detection limit of 15.4 ppb for Cu2+ in aqueous media and excellent recyclability were also observed.
Co-reporter:Kaoru Otsuka, Takuya Kondo, Ryuhei Nishiyabu, and Yuji Kubo
The Journal of Organic Chemistry 2013 Volume 78(Issue 11) pp:5782-5787
Publication Date(Web):May 13, 2013
DOI:10.1021/jo4006238
The conformation of resorcin[4]arene cavitand system 1 was controlled by DMSO through a hydrogen bonding network between benzodiazaborole NHs of the cavitand flaps and DMSO molecules to stabilize the vase form. Subsequently, a guest-binding cavity of 1 was formed to accommodate tetraalkylammonium guest 3, permitting the monitoring of the guest by the unaided eye as a result of a CH−π interaction between the benzodiazaborole π-donor group and the guest.
Co-reporter:Ryuhei Nishiyabu, Hiroyasu Kobayashi and Yuji Kubo
RSC Advances 2012 vol. 2(Issue 16) pp:6555-6561
Publication Date(Web):14 May 2012
DOI:10.1039/C2RA20516E
A new type of boronate hydrogel with covalently bound dansyldiethylenetriamine as an indicator has been developed; the gel networks are based on boronate esterification of poly(vinylalcohol) with benzene-1,4-diboronic acid. In this approach, phenylboronic acid-appended N-dansyldiethylenetriamine 1 was newly synthesized to be incorporated into the gel matrix. The resulting gel film showed an absorption band at 336 nm and fluorescence at 511 nm when excited at 340 nm in water. The fluorescence measurements indicated that at neutral conditions using a HEPES buffer, the gel film was selectively quenched after immersion in an aqueous solution of Cu2+ for 30 min. The response had minimal interference from other metal ions such as Na+, K+, Mg2+, Ca2+, Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, Al3+, and Pb2+, which was noteworthy because dansyldiethylenetriamine alone responds to Hg2+ and Ni2+ in addition to Cu2+ in water. The reversible sensing capability was also evaluated by rinsing the film with an aqueous solution of ethylenediaminetetraacetic acid (EDTA). The gel was found to be a reusable and free-standing film capable of visually detecting Cu2+, providing a simple and expedient tool for on-site monitoring of Cu2+ in environmental applications such as water analysis.
Co-reporter:Dr. Ryuhei Nishiyabu;Shiori Teraoka;Yusuke Matsushima ; Yuji Kubo
ChemPlusChem 2012 Volume 77( Issue 3) pp:201-209
Publication Date(Web):
DOI:10.1002/cplu.201100008
Abstract
Pyridine-assisted sequential boronate esterification of benzene-1,4-diboronic acid and 1,2,4,5-tetrahydroxybenzene has induced hierarchical molecular self-assembly, and in turn producing well-defined submicrospheres. Spectroscopic analyses such as FE-SEM, TEM, DLS, NMR, XRD, and IR absorption spectroscopy indicates that the particles are composed of lamellar structures of sp2-hybridized trigonal planar poly(dioxaborole). The spontaneous self-organization is ascribable to reactive layer-by-layer assembly through sequential boronate esterification of the diboronic acid and the tetrahydroxybenzene whereby initially formed oligo(dioxaborole) may provide a platform for further reactions, thus resulting in the production of submicrospheres. It is interesting to note that the dynamic covalent functionality as a result of the dioxaborole linkage induced a stimuli-responsive change in morphology by not only a pH switch but also the exchange reaction with pentaerythritol. Further, a selective saccharide-induced change in the submicrosphere morphology was observed through a simple exchange reaction of dynamic covalent boronate esters with saccharides in THF; the selective change in morphology is visually detected through the color change in the solution. These findings can provide a useful insight into the design of stimuli-responsive hierarchical architectures based on boron-containing dynamic covalent bond.
Co-reporter:Ryuhei Nishiyabu, Yuji Kubo, Tony D. James and John S. Fossey
Chemical Communications 2011 vol. 47(Issue 4) pp:1124-1150
Publication Date(Web):29 Nov 2010
DOI:10.1039/C0CC02921A
Dynamic covalent functionality has been acknowledged as a powerful tool for the construction of organised architectures, the reversible nature thermodynamically facilitates self-control and self-correction. The use of boronic acids complexation with diols and their congeners has already shown great promise in realising and developing reversible boron-containing multicomponent systems with dynamic covalent functionality. The structure-directing potential has lead to the development of a variety of self-organisation involving not only macrocycles, cages and capsules, but also porous covalent organic frameworks and polymers. Structure controls as well as remarkable synthesis are highlighted in this feature article.
Co-reporter:Ken-ichi Saitou, Ryuhei Nishiyabu, Masahiko Iyoda, Yuji Kubo
Tetrahedron 2011 67(50) pp: 9685-9689
Publication Date(Web):
DOI:10.1016/j.tet.2011.10.032
Co-reporter:Yuji Kubo, Kazusa Tsuruzoe, Sachiko Okuyama, Ryuhei Nishiyabu and Takashi Fujihara
Chemical Communications 2010 vol. 46(Issue 20) pp:3604-3606
Publication Date(Web):09 Apr 2010
DOI:10.1039/C0CC00259C
Resorcin[4]arene cavitand 1 with 1,3,2-benzodiazaborolyl walls was newly synthesized. It showed a large blue shift in the fluorescence spectra upon selective complexation with alkyltrimethylammonium salts in CH2Cl2–DMSO (9:1 v/v); this shift was detectable with the naked eye.
Co-reporter:Tsuyoshi Minami, Ryuhei Nishiyabu, Masahiko Iyoda and Yuji Kubo
Chemical Communications 2010 vol. 46(Issue 45) pp:8603-8605
Publication Date(Web):04 Oct 2010
DOI:10.1039/C0CC03179H
Fine shape-control of gold nanoparticles was achieved in the presence of an amphiphilic polythiophene with an isothiouronium pendant, by varying the experimental conditions for the crystallization; we succeeded to prepare π-conjugated polythiophene-capped Au nanoplates, Au nanocubes and Au nanoparticles with an average spherical diameter of (7.7 ± 1.6) nm.
Co-reporter:Yuji Kubo, Yu Minowa, Takayuki Shoda, Kimiya Takeshita
Tetrahedron Letters 2010 Volume 51(Issue 12) pp:1600-1602
Publication Date(Web):24 March 2010
DOI:10.1016/j.tetlet.2010.01.070
A new type of π-extended 4-bora-3a,4a-diaza-s-indacene (BODIPY dye), bis(isoindole)-derived benzo[1,3,2]oxazaborinine 1, has been synthesized by seven-step procedure from 2-methoxybenzoic acid methyl ester. The benzannulation of the pyrrole ring and the formation of a structurally strained intramolecular B–O ring enable the dye to absorb near-infrared light at ca. 750 nm with a molecular extinction coefficient (ε) of ca 8.3 × 104 M−1 cm−1 in THF. The absorption properties are discussed on the basis of DFT calculations. Interestingly, a film of 5,5-dihexyloxy derivative 1b, which was fabricated by a spin-coating procedure on a glass plate, exhibited a dramatic bathochromic shift of absorbance as compared to the solution, with λmax of 922 nm.
Co-reporter:Tsuyoshi Minami Dr.
Chemistry – An Asian Journal 2010 Volume 5( Issue 3) pp:605-611
Publication Date(Web):
DOI:10.1002/asia.200900444
Abstract
A water-soluble isothiouronium-attached polythiophene (1poly) is prepared for the first time by the oxidative polymerization of 3-(3-(N-(2-methoxyethoxy)ethyl-N-methyl-S-isothiouronio)propoxy-4-methylthiophene (1) with FeCl3. The gel-permeation chromatography analysis allows us to estimate the number average molecular weight (Mn) and the polydispersity index (PDI) to be 5.68×105 and 1.4, respectively. The polymers (excited at 438 nm) show an absorption band at 438 nm and fluorescence at 546 nm, with 1.2 % fluorescence quantum yield when fluorescein was used as a reference. The pH-dependent absorption spectra at varying pH, indicates that aggregation starts at neutral conditions. At pH 5.5, 1poly exhibits a significant quenching in the fluorescence upon the addition of phytate (IP6), as a plausible analyte. This response is higher than that in the case of other anions such as adenosine 5-triphosphate (ATP), pyrophosphate (PPi), cis,cis-1,3,5-cyclohexanetriol triphosphate (CTP3), and H2PO4−. As inferred from the SEM measurement, the phytate-induced spectral change has been explained on the basis of the π-stacked aggregation of the polymer.
Co-reporter:Kenichi Kataoka, Sachiko Okuyama, Tsuyoshi Minami, Tony D. James and Yuji Kubo
Chemical Communications 2009 (Issue 13) pp:1682-1684
Publication Date(Web):12 Feb 2009
DOI:10.1039/B900102F
Boron-contained molecular capsules triggered by amines are described for the first time; when Et3N was employed as a chemical stimulus the Lewis acidEt3NH+, produced by solvolysis reaction on the boron, was found to be encapsulated in the internal cavity, whereas use of nBu3N led to the related dynamic capsule capable of accommodating several guest species including Cs+.
Co-reporter:Kaori Sakakibara, Yuki Takahashi, Ryuhei Nishiyabu and Yuji Kubo
Journal of Materials Chemistry A 2017 - vol. 5(Issue 15) pp:NaN3691-3691
Publication Date(Web):2017/02/24
DOI:10.1039/C7TC00405B
Driven by our motivation to develop a chemodosimeter for the visual detection of hydrogen peroxide (H2O2), we synthesized for the first time a dipyrrin (1) with 4-pinacolborylbenzyloxy groups. An EtOH solution of Zn2+-coordinated 1 was reddish-violet in color, with a λmax value of 538 nm. However, the addition of H2O2 into the solution induced a remarkable color change from reddish-violet to blue. The time-dependent change in the absorption band showed two step kinetic processes in their kinetic profiles, where a new peak with λmax = 581 nm appeared within 13 min (k1 = 0.370 min−1), followed by a slower change in the spectra (k2 = 0.00371 min−1) concomitant with a further bathochromic shift of 18 nm. NMR and mass spectroscopic analyses indicated that the kinetically slower process may be responsible for a change in the coordination mode of the Zn2+ ion through a H2O2-triggered self-immolative reaction in the 4-pinacolborylbenzyloxy groups. Basic conditions achieved through the addition of tetrabutylammonium hydroxide (TBAOH) led to the acceleration of not only the H2O2-triggered colorimetric change but also the turn-on fluorescence, thus allowing dual-mode sensing of H2O2. For practical applications, the related drop-cast paper strips were fabricated to visually detect H2O2 vapor.
Co-reporter:Ryuhei Nishiyabu, Shiho Ushikubo, Yuka Kamiya and Yuji Kubo
Journal of Materials Chemistry A 2014 - vol. 2(Issue 38) pp:NaN15852-15852
Publication Date(Web):2014/07/30
DOI:10.1039/C4TA03268C
A multicolor fluorescent hydrogel sensor containing two types of fluorescent dyes with an amidoquinoline receptor unit and a rhodamine chromophore covalently incorporated into a polyvinyl alcohol–boronate matrix was prepared. Although the gel film exhibited red emission due to the rhodamine chromophore, the addition of a small amount of Zn2+ ions induced a multicolor fluorescence response, which included white-light emission, of the film in water. The change in emission color is ascribed to fluorescence enhancement of the amidoquinoline moiety upon binding to Zn2+ ions with an association constant of (3.5 ± 0.2) × 105 M−1. In contrast, a negligible change in the emission color of the gel film was observed in the presence of Na+, K+, Mg2+, Ca2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Hg2+, Al3+, and Pb2+ ions. The selectivity of the gel film enabled visual detection of Zn2+ ions in tap water. Moreover, the film could be reused as a sensor strip after treatment with ethylenediaminetetraacetic acid.
Co-reporter:Ryuhei Nishiyabu, Yasuyuki Sugino and Yuji Kubo
Chemical Communications 2013 - vol. 49(Issue 84) pp:NaN9871-9871
Publication Date(Web):2013/08/30
DOI:10.1039/C3CC45739G
The facile surface functionalization of surfactant-free organic microparticles composed of polymeric 2,4,8,10-tetraoxa-3,9-diboraspiro[5.5]undecane allowed us to develop white-light emissive chemosensors for the real-time visual detection of Cu2+ in HEPES buffer (pH 7.0) due to a synergistic response of fluorophores grafted onto the particles. A detection limit of 15.4 ppb for Cu2+ in aqueous media and excellent recyclability were also observed.
Co-reporter:Yuji Kubo, Ryuhei Nishiyabu and Tony D. James
Chemical Communications 2015 - vol. 51(Issue 11) pp:NaN2020-2020
Publication Date(Web):2014/11/24
DOI:10.1039/C4CC07712A
Current progress on hierarchical supramolecules using boronic acids has been highlighted in this feature article. Boronic acids can participate in “click reactions” with diols and their congeners with dynamic covalent functionality. By comprehensively exploring versatile sequential boronate esterification linkages between plural boronic acid-appended molecules and multiple hydroxyl counterparts, not only versatile supramolecular polymers but also structurally well-defined network nanostructures have been developed. In addition orthogonal interactions such as dative bonds of the boron center with Lewis bases have led to the formation of hierarchical nano/microstructures. Boronate systems have the potential to be used as materials for smart gels, chemosensors, active architectures for electronics, heterogeneous catalysts, chemical-stimulus responsive systems for drug delivery, etc. Here, we fully discuss the feasibility of the structure-directing ability of boronic acids from the standpoint of the generation of new smart materials.
Co-reporter:Tsuyoshi Minami, Fereshteh Emami, Ryuhei Nishiyabu, Yuji Kubo and Pavel Anzenbacher
Chemical Communications 2016 - vol. 52(Issue 50) pp:NaN7841-7841
Publication Date(Web):2016/05/16
DOI:10.1039/C6CC02923J
Self-assembled colorimetric sensors have been prepared from ZnII–DPA-attached phenylboronic acid (1·Zn) and catechol-type dyes. The 1·Zn–dye sensors display selectivity towards oligophosphate over monophosphates. The colorimetric sensor assay (1·Zn–dye) is utilized to monitor a model of a metabolic reaction where ATP is hydrolyzed to pyrophosphate (PPi) and AMP.
Co-reporter:Ryuhei Nishiyabu, Yuji Kubo, Tony D. James and John S. Fossey
Chemical Communications 2011 - vol. 47(Issue 4) pp:NaN1150-1150
Publication Date(Web):2010/11/29
DOI:10.1039/C0CC02921A
Dynamic covalent functionality has been acknowledged as a powerful tool for the construction of organised architectures, the reversible nature thermodynamically facilitates self-control and self-correction. The use of boronic acids complexation with diols and their congeners has already shown great promise in realising and developing reversible boron-containing multicomponent systems with dynamic covalent functionality. The structure-directing potential has lead to the development of a variety of self-organisation involving not only macrocycles, cages and capsules, but also porous covalent organic frameworks and polymers. Structure controls as well as remarkable synthesis are highlighted in this feature article.
Co-reporter:Kenichi Kataoka, Sachiko Okuyama, Tsuyoshi Minami, Tony D. James and Yuji Kubo
Chemical Communications 2009(Issue 13) pp:NaN1684-1684
Publication Date(Web):2009/02/12
DOI:10.1039/B900102F
Boron-contained molecular capsules triggered by amines are described for the first time; when Et3N was employed as a chemical stimulus the Lewis acidEt3NH+, produced by solvolysis reaction on the boron, was found to be encapsulated in the internal cavity, whereas use of nBu3N led to the related dynamic capsule capable of accommodating several guest species including Cs+.
Co-reporter:Okta Suryani, Yuta Higashino, Jacob Yan Mulyana, Masayoshi Kaneko, Takayuki Hoshi, Koichiro Shigaki and Yuji Kubo
Chemical Communications 2017 - vol. 53(Issue 50) pp:NaN6787-6787
Publication Date(Web):2017/06/01
DOI:10.1039/C7CC02730C
Dye-sensitized photoelectrochemical cells (DSPECs) composed of a new near-infrared BODIPY dye D1 that is co-deposited with a ruthenium water oxidation catalyst C1 have been fabricated. The devices at pH 7.2 showed an excellent Faradaic efficiency of H2 production (65.8%) that was 5.4 times larger than that of a triphenylamine photosensitizer D2 and C1-coadsorbed cell.
Co-reporter:Yuji Kubo, Kazusa Tsuruzoe, Sachiko Okuyama, Ryuhei Nishiyabu and Takashi Fujihara
Chemical Communications 2010 - vol. 46(Issue 20) pp:NaN3606-3606
Publication Date(Web):2010/04/09
DOI:10.1039/C0CC00259C
Resorcin[4]arene cavitand 1 with 1,3,2-benzodiazaborolyl walls was newly synthesized. It showed a large blue shift in the fluorescence spectra upon selective complexation with alkyltrimethylammonium salts in CH2Cl2–DMSO (9:1 v/v); this shift was detectable with the naked eye.
Co-reporter:Tsuyoshi Minami, Ryuhei Nishiyabu, Masahiko Iyoda and Yuji Kubo
Chemical Communications 2010 - vol. 46(Issue 45) pp:NaN8605-8605
Publication Date(Web):2010/10/04
DOI:10.1039/C0CC03179H
Fine shape-control of gold nanoparticles was achieved in the presence of an amphiphilic polythiophene with an isothiouronium pendant, by varying the experimental conditions for the crystallization; we succeeded to prepare π-conjugated polythiophene-capped Au nanoplates, Au nanocubes and Au nanoparticles with an average spherical diameter of (7.7 ± 1.6) nm.
Co-reporter:Aiko Nonaka, Shoichi Horie, Tony D. James and Yuji Kubo
Organic & Biomolecular Chemistry 2008 - vol. 6(Issue 19) pp:NaN3625-3625
Publication Date(Web):2008/08/12
DOI:10.1039/B808027E
A new strategy for the fluorescent detection of multi-phosphates in aqueous solution is presented here. ZnII–DPA(DPA = dipicolylamine)-appended phenylboronic acid 1·Zn forms an assembly with alizarin dye in MeOH–10 mM HEPES (1 : 1 v/v) containing 10 mM NaCl at pH 7.4 at 25 °C, in which the dye binds favorably to the coordinated zinc(II) in the ZnII–DPA moiety. Addition of pyrophosphate (PPi) as a putative analyte causes reorganization of the complex to produce an alternative boronate ester assembly, which causes an increase in fluorescence, detectable by the naked eye. It is interesting to note that the system exhibited PPi-selectivity over other phosphates such as ATP (adenosine 5′-triphosphate), ADP (adenosine 5′-diphosphate), AMP (adenosine 5′-monophosphate) and Pi (inorganic phosphate); the competitive assay employed to determine the apparent association constants of 1·Zn with the anion analytes allows us to estimate that the binding with PPi [(1.6 ± 0.04) × 106 M−1], is 10-fold and 84-fold higher than with ATP and ADP, respectively. The sensing mechanism of 1·Zn in the presence of alizarin dye is explored using pH titrations and structural information is obtained using NMR.
Co-reporter:Yuji Kubo, Daichi Eguchi, Asaki Matsumoto, Ryuhei Nishiyabu, Hidenori Yakushiji, Koichiro Shigaki and Masayoshi Kaneko
Journal of Materials Chemistry A 2014 - vol. 2(Issue 15) pp:NaN5211-5211
Publication Date(Web):2014/01/24
DOI:10.1039/C3TA15340A
Novel boron–dibenzopyrromethene dyes with thienyl-cyanoacrylic acid units were synthesized and characterized for application in dye-sensitized solar cells (DSSCs); the dyes feature intense absorption bands in the longer wavelength region with λmax values of 647 nm (ε = 1.57 × 105 M−1 cm−1) for 1, which has two anchoring units, 660 nm (ε = 1.09 × 105 M−1 cm−1) for regioisomer 2, and 644 nm (ε = 1.39 × 105 M−1 cm−1) for 3, which has a single anchoring unit. Density functional theory (DFT) analysis revealed that these absorption properties are mainly characterized by intramolecular charge transfer from the dibenzopyrromethene core to the thienyl-cyanoacrylic acid unit that depend on both the number of anchoring groups and the position of the thienyl-cyanoacrylic acid unit on the isoindole ring. The relationship between the chemical structures and cell properties of these dyes was investigated. Although the short circuit photocurrent density (Jsc) value of a 1-loaded cell is larger than that of a 3-loaded cell, which reflects the results of the incident photon-to-charge carrier efficiency (IPCE) spectra, the 1-loaded cell has a lower open circuit voltage (Voc) and fill factor (FF). Accordingly, overall power-to-current conversion efficiencies of 5.24 and 5.48% were obtained for a 1-loaded cell and 3-loaded cell, respectively, under 100 mW cm−2 AM1.5G simulated light. On the other hand, the cell containing butterfly-shaped regioisomer 2, which showed improved intramolecular charge transfer, has an overall power-to-current conversion efficiency of 6.06%; this value is the highest published for BODIPY dyes even though the sensitizer does not contain any strong donor units, such as arylamines.
Co-reporter:Ayumi Ozawa, Ai Shimizu, Ryuhei Nishiyabu and Yuji Kubo
Chemical Communications 2015 - vol. 51(Issue 1) pp:NaN121-121
Publication Date(Web):2014/11/03
DOI:10.1039/C4CC07405J
Boronate nanoparticles with built-in tetraphenylethylene (TPE) have been prepared. Their emissive color tuning by altering the amount of rhodamine B grafted onto the surface gave white-light emissive nanoparticles. They showed reversible and thermo-responsive emission in the temperature range of 5–65 °C in water, which enabled them to serve as a bright nanothermometer.
![Stannane, tributyl(5,5''-dihexyl[2,2':3',2''-terthiophen]-5'-yl)-](http://img.cochemist.com/ccimg/443000/442911-12-8.png)
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ylene)](http://img.cochemist.com/ccimg/699100/699010-83-8.png)
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ylene)](http://img.cochemist.com/ccimg/699100/699010-83-8_b.png)
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