A Supramolecular Biosensor for Rapid and High-Throughput Quantification of a Disease-Associated Niacin Metabolite.

Metabolic abnormalities play a pivotal role in various pathological conditions, necessitating the quantification of specific metabolites for diagnosis. While mass spectrometry remains the primary method for metabolite measurement, its limited throughput underscores the need for biosensors capable of rapid detection. Previously, we reported that pillar[6]arene with 12 carboxylate groups (P6AC) forms host-guest complexes with 1-methylnicotinamide (1-MNA), which is produced in vivo by nicotinamide -methyltransferase (NNMT).

Optically active poly(diphenylacetylene)s showing solvent-dependent helix inversion accompanied by modulation of helix inversion barriers.

Symmetrically substituted poly(diphenylacetylene)s bearing optically active 2-octyloxycarbonyl groups at the -positions of the pendant phenyl rings not only show a unique solvent-dependent helix inversion to afford diastereomeric right- and left-handed helical polymers but also significant unprecedented solvent-dependent changes in the helix inversion barrier of the polymer backbone resulting in switching between static or dynamic behavior of the helical polymers at approximately room temperature depending on the solvents used.

Dynamics of Molecular Self-Assembly of Short Peptides at Liquid-Solid Interfaces - Effect of Charged Amino Acid Point Mutations.

Self-organizing solid-binding peptides on atomically flat solid surfaces offer a unique bio/nano hybrid platform, useful for understanding the basic nature of biology/solid coupling and their practical applications. The surface behavior of peptides is determined by their molecular folding, which is influenced by various factors and is challenging to study. Here, the effect of charged amino acids is studied on the self-assembly behavior of a directed evolution selected graphite-binding dodecapeptide on graphite surface.

Control of One-Handed Helicity in Polyacetylenes: Impact of an Extremely Small Amount of Chiral Substituents.

Controlling the one-handed helicity in synthetic polymers is crucial for developing helical polymer-based advanced chiral materials. We now report that an extremely small amount of chiral biphenylylacetylene (BPA) monomers (ca. 0.

Synthesis of optically active star polymers consisting of helical poly(phenylacetylene) chains by the living polymerization of phenylacetylenes and their chiroptical properties.

Star polymers consisting of three helical poly(phenylacetylene) chains with a precisely controlled molecular weight (molar mass dispersity < 1.03) were successfully synthesized by the living polymerization of phenylacetylene derivatives with a Rh-based multicomponent catalyst system comprising trifunctional initiators, which have three phenylboronates centered on a benzene ring, the Rh complex [Rh(nbd)Cl], diphenylacetylene, triphenylphosphine, and a base. The analysis of chiroptical properties of the optically active star polymers obtained by the living polymerization of optically active phenylacetylene derivatives revealed that the star polymers exhibited chiral amplification properties owing to their unique topology compared with the corresponding linear polymers.

Insight into stability of dithiocarbamate-modified adsorbents: Oxidation of dithiocarbamate.

We previously reported that monoalkyl dithiocarbamate-modified cellulose (DMC) exhibited excellent adsorption performance for arsenite (As), cadmium (Cd), lead (Pb), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd). However, its adsorption capability for As decreased by 96.4% after two weeks of storage at 40 °C under an air atmosphere.

Revisiting the Synthesis of Cellulose Acrylate and Its Modification via Michael Addition Reactions.

The synthesis of cellulose acrylate from cellulose with acryloyl chloride has been problematic due to unexpected gelation of the reaction mixture, but we discovered that the use of bulky amines was crucial for the reproducibility of the synthesis of cellulose acrylate. The solubility of the obtained cellulose acrylate depended on the reaction conditions due to the possible cross-linking oxa-Michael reaction between a remaining hydroxy group and the introduced acrylate group. The synthesized cellulose acrylate worked as a useful precursor of chemically modified cellulose materials because it reacted with various functionalized nucleophiles such as secondary amines and thiols as a Michael donor.

Facile Synthesis of Linear and Cyclic Poly(diphenylacetylene)s by Molybdenum and Tungsten Catalysis.

Improved methods for the synthesis of linear and cyclic poly(diphenylacetylene)s by polymerization of the corresponding diphenylacetylenes using MoCl - and WCl -based catalytic systems have been developed. MoCl induces migratory insertion polymerization of diphenylacetylenes in the presence of arylation reagents such as Ph Sn and ArSn Bu to produce cis-stereoregular linear poly(diphenylacetyelene)s with high molecular weights (number-average molar mass (M )=30,000-3,200,000) in good yields (up to 98 %). On the other hand, WCl induces ring expansion polymerization of diphenylacetylenes in the presence of Ph Sn or reducing reagents to produce cis-stereoregular cyclic poly(diphenylacetylene)s with high molecular weights (M =20,000-250,000) in moderate to good yields (up to 90 %).

Helicity induction and memory of a lipophilic Brønsted acid-type poly(phenylacetylene) in non-polar solvents.

A novel lipophilic Brønsted acid-type PPA (poly-1-H) bearing a sulfonylphosphoramidic acid moiety, covered with a dynamically axially chiral biphenyl pendant, was synthesized and found to form a preferred-handed helical conformation in non-polar solvents upon complexation with non-racemic amines. This induced helicity was maintained after replacement with achiral amines ("dynamic helicity memory"). In addition, poly-1-H exhibited "static helicity memory" in which the induced helical conformation was maintained in non-polar solvents, even after acidification with a stronger acid without replacement with achiral amines.

Amplified Chirality Transfer to Aromatic Molecules through Non-specific Inclusion by Amorphous, Hyperbranched Poly(fluorenevinylene) Derivatives.

Optically active, hyperbranched, poly(fluorene-2,4,7-triylethene-1,2-diyl) [poly(fluorenevinylene)] derivatives bearing a neomenthyl group and a pentyl group at the 9-position of the fluorene backbone at various ratios acted as a chirality donor (host polymers) efficiently included naphthalene, anthracene, pyrene, 9-phenylanthracene, and 9,10-diphenyanthracene as a chirality acceptor (guest molecules) in their interior space in film as well as in solution, with the guest molecules exhibiting intense circular dichroism through chirality transfer with chirality amplification. The efficiency of the chirality transfer was much higher with higher-molar-mass polymers than lower-molar-mass ones as well as with hyperbranched polymers compared to the analogous linear ones. The hyperbranched polymers include the small molecules in their complex structure without any specific interactions at various stoichiometries.

Ultra-fast One-Handed Helix Induction and Its Static Helicity Memory in a Poly(biphenylylacetylene) with a Catalytic Amount of Chiral Ammonium Salts.

We report an ultra-fast helix induction and subsequent static helicity memory in poly(biphenylylacetylene) (PBPA-A) assisted by a catalytic amount of nonracemic ammonium salts comprised of non-coordinating tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF ) as a counter anion. The remarkable acceleration of the helix-induction rate in PBPA-A accompanied by the significant amplification of the asymmetry relies on the two methoxymethoxy groups of the biphenyl pendants, which can gain access to enfold the chiral ammoniums in a crown-ether manner in specific aromatic solvents, leading to ultra-fast helicity induction, which is completed within 30 s. In aromatic solvents, helicity memory is lost rapidly, but is quite stable in long-chain hydrocarbons.

Full Control of the Chiral Overpass Effect in Helical Polymers: P/M Screw Sense Induction by Remote Chiral Centers After Bypassing the First Chiral Residue.

In helical polymers, helical sense induction is usually commanded by teleinduction mechanism, where the largest substituent of the chiral residue directly attached to the main chain is the one that commands the helical sense. In this work, different helical structures with different helical senses are induced in a helical polymer [poly-(phenylacetylene)] when the conformational composition of two different dihedral angles of a pendant group with more than two chiral residues is tamed. Thus, while the dihedral angle at chiral residue 1 [(R)- or (S)-alanine], attached to the backbone, produces an extended or bent conformation in the pendant resulting in two scaffolds with different stretching degree, the second dihedral angle at chiral residue 2 [(R)- or (S)-methoxyphenylacetamide] places the substituents of this chiral center in a different spatial orientation, originating opposite helical senses at the polymer that are induced through a total control of the "chiral overpass effect".

Effect of Oxidation on the Chiroptical Properties of Sulfur-Bridged Binaphthyl Dimers.

A series of axially chiral sulfur-bridged dimers were prepared from 1,1'-binaphthyl-2,2'-diol and subsequently oxidized to the respective sulfones. The chiroptical properties of the chiral chromophores were studied as a function of the oxidation state. Upon oxidation, an increase in quantum yields was observed for directly linked sulfur bridged binaphthyls (0.

Non-uniform Self-folding of Helical Poly(fluorenevinylene) Derivatives in the Solid State Leading to Amplified Circular Dichroism and Circularly Polarized Light Emission.

An unprecedented non-uniform self-folding of artificial polymer chains composed of turn moieties and stretched segments is presented through the design of a set of optically active poly(fluorene-2,7-diylethene-1,2-diyl) (poly(fluorenevinylene)) derivatives bearing a neomenthyl group and a pentyl group attached at the 9-position of fluorene backbone at various ratios. The folded structure is formed and stabilized through inter-chain interactions in the solid state, leading to remarkably enhanced chiroptical properties (chirality amplification) in terms of circular dichroism (CD) and circularly polarized light (CPL) emission. This phenomenon is rationalized by experimental and theoretical CD and CPL spectral analyses.

Cross-linked dithiocarbamate-modified cellulose with enhanced thermal stability and dispersibility as a sorbent for arsenite removal.

Numerous reports have described dithiocarbamate (DTC)-modified cellulose sorbents that can selectively separate metal ions from water. We have previously synthesized a novel sorbent modified with DTC containing N-heterocycles in the backbone for the selective removal of hazardous metal ions. The sorbent was found to partially dissolve and aggregate in solution, reducing its sorption capacity.

Enantioseparation on helical poly(diphenylacetylene)s bearing optically-active pendants: Effects of differences in higher-order structures of kinetically-trapped and thermodynamically-stable states on chiral recognition ability.

An optically-active poly(diphenylacetylene) (PDPA) bearing carboxy pendant groups with left-handed helicity memory (M-h-poly-1), synthesized using the noncovalent helicity-induction-and-memory strategy, was converted into a PDPA bearing optically-active pendant groups through an amide bonding (M-h-poly-2S), while maintaining the left-handed helicity memory, by reaction with (S)-1-phenylethylamine ((S)-2) using a condensing reagent at room temperature. Its chiral recognition ability was investigated as a chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). M-h-poly-2S exhibited significantly different chiral recognition ability towards racemates compared to the previously reported corresponding helical PDPA bearing the same optically-active pendant groups (M-h-poly-2S) (prepared by the reaction of an optically-inactive PDPA bearing carboxy pendants with (S)-2, followed by thermal annealing, to induce a left-handed helical structure in the polymer main chain).

Well-Controlled Living Polymerization of Phenylacetylenes in Water: Synthesis of Water-Soluble Stereoregular Telechelic Poly(phenylacetylene)s.

Well-controlled living polymerization of water-soluble phenylacetylene derivatives in water was achieved for the first time using a multicomponent catalytic system consisting of [Rh(nbd)Cl] , an aryl boronic acid, diphenylacetylene having carboxy groups, a tetraalkylammonium hydroxide, and a water-soluble triphenylphosphine. This catalytic system enables a direct synthesis of various water-soluble cis-stereoregular poly(phenylacetylene)s having a narrow molecular weight distribution, the molecular weight of which can be controlled by the initial feed ratio of the monomer to the catalyst. Moreover, the syntheses of water-soluble telechelic poly(phenylacetylene)s having various functional groups at both chain ends as well as a water-soluble block copolymer were achieved.

Well-Controlled Living Polymerization of N-Propargylamides and Their Derivatives by Rhodium Catalysis.

A substantially improved method for living polymerization of N-propargylamides and their derivatives has been developed. Rhodium(I) complexes bearing an aryl-substituted 1,3,5-hexatriene chain can work as excellent initiators of the polymerization of such non-conjugated terminal alkynes to give the corresponding cis-stereoregular polymers having a narrow molecular weight distribution. The typical living nature has been confirmed by investigating the effects of initial feed ratios of the monomer to the initiator on the molecular weight of the resulting polymers as well as multistage polymerization.

Solvent-dependent helix inversion in optically active poly(diphenylacetylene)s and their chiral recognition abilities as chiral stationary phases for high-performance liquid chromatography.

We report the first example of solvent-dependent helix inversion in poly(diphenylacetylene) (PDPA) derivatives. Asymmetrically substituted PDPAs bearing optically active substituents linked through amide bonds formed preferred-handed helical conformations because of the optically active substituents in the pendants, whose helix-senses were inverted upon thermal annealing in polar solvents such as N,N-dimethylformamide and dimethylsulfoxide and in nonpolar solvents such as tetrachloroethane. Unlike the solvent-dependent helix inversion reported for other dynamic helical polymers, the macromolecular helicity induced in the polymer backbone of these PDPAs upon thermal annealing was stably maintained at room temperature, independent of the solvent polarity.

Visualisation of helical structures of poly(diphenylacetylene)s bearing chiral amide pendants by atomic force microscopy.

The helical structures of poly(diphenylacetylene)s bearing optically active substituents linked through amide bonds and with a helicity memory have been visualised using atomic force microscopy. The polymers self-assembled into an ordered 2D monolayer on highly oriented pyrolytic graphite upon exposure to solvent vapour, whose helical pitch and handedness (right- and left-handed) were for the first time directly revealed at molecular resolution.

Speciation analysis of inorganic selenium in wastewater using a highly selective cellulose-based adsorbent via liquid electrode plasma optical emission spectrometry.

Speciation of selenium (Se) is typically carried out using a sophisticated technique such as ICP-MS after preconcentration using an adsorbent; however, the separation and preconcentration of inorganic Se has not been realized in the solutions containing high concentrations of SO. A dithiocarbamate-modified cellulose (DMC) was used in this study for the selective extraction and preconcentration of inorganic Se in wastewater, with a portable liquid electrode plasma-optical emission spectrometry (LEP-OES) being employed for quantification. DMC was found to selectively and quantitatively adsorb selenite (Se) over a wide range of pH (1.

Understanding the Polymerization of Diphenylacetylenes with Tantalum(V) Chloride and Cocatalysts: Production of Cyclic Poly(diphenylacetylene)s by Low-Valent Tantalum Species Generated in Situ.

A systematic investigation of the polymerization of representative diphenylacetylenes with TaCl and cocatalysts suggested that low-valent Ta species, which are formed by in situ reduction of TaCl by the cocatalysts, are involved in the polymerization and that the polymerization reaction proceeds by an insertion ring expansion mechanism via the formation of tantalacyclopentadiene intermediates, rather than the previously considered metathesis mechanism. This polymerization mechanism indicates the production of unprecedented -stereoregular cyclic poly(diphenylacetylene)s. Indeed, the possibilities of a cyclic structure and high -stereoregularity of the resulting polymers were reasonably supported by the results of their detailed atomic force microscopy (AFM) and NMR analyses, respectively.

Rhodium(I) Complexes Bearing an Aryl-Substituted 1,3,5-Hexatriene Chain: Catalysts for Living Polymerization of Phenylacetylene and Potential Helical Chirality of 1,3,5-Hexatrienes.

Unique bench-stable rhodium(I) complexes bearing an aryl-substituted 1,3,5-hexatriene chain have been synthesized by reactions of (bicyclo[2.2.1]hepta-2,5-diene)rhodium(I) chloride dimer ([Rh(nbd)Cl] ) with aryl boronic acids and diphenylacetylenes in the presence of a 50 % aqueous solution of KOH.