Miyuki Narita

Metal sensor of water soluble dansyl-modified thiacalix[4]arenes

Abstract The water soluble thiacalix[4]arene derivatives, which are modified with di- and tri-dansyl moieties,have been prepared to investigate their metal sensing abilities in aqueous solution. It is the first example that water soluble thiacalix[4]arene derivatives can detect metal cations directly in aqueous solution by variation of fluorescence intensity upon addition of a metal cation.

The Synthesis and X-Ray Structure of 1,2,3,4-Cyclobutane Tetracarboxylic Dianhydride and the Preparation of a New Type of Polyimide Showing Excellent Transparency and Heat Resistance

Some polyimide films based on cyclobutane-1,2,3,4-tetracarboxylic dianhy- dride (CBDA) and aromatic diamines were synthesized to investigate their temperature resistance and percent transmission of light. The preparations of CBDA were investi- gated; they produced almost 10 times the yield of CBDA in comparison to yields obtained by previous methods. The configuration of CBDA was determined by X-ray analysis to be cis-trans-cis. The polymer films showed excellent thermal resistance and were transparent and colorless, desirable characteristics for practical applications in the field of polymer engineering. However, the polymer obtained from a pyromellitic dianhydride instead of from CBDA was deep yellow and not desirable for high-qualified display materials such as liquid-crystal displays. The percent transmission of the polymers obtained from CBDA and aromatic diamines ranged from 81.5 to 85.8%, whereas the deep-yellow polymers showed low percent transmissions ranging from 48 to 63.9%.

Fluorescent Pyrrolinone-modified Cyclodextrins as a Chemo-sensor for Organic Guests

Fluorescent pyrrolinone-modified β- and γ-cyclodextrins (β-1 and γ-1, respectively) have been synthesized as a fluorescent chemo-sensor for organic compounds such as terpenoids and bile acids. The host compounds show a pure monomer fluorescence around 472 nm, the intensity of which decreased when 1-adamantanecarboxylic acid, p-aminobenzoic acid, benzoic acid, phthalic acid or cyclohexanecarboxylic acid were used as a guest in an aqueous solution of pH 5.90. On the other hand, in Menzel buffer solution of pH 9.09, the fluorescent intensity is increased by accommodation of these guest molecules. The increase was seen with other guests such as terpenoids, amino compounds and sodium bile acid salts in a Menzel buffer solution. The extent of fluorescence variation with a guest is employed to display the chemo-sensor ability of these hosts. The sensing parameter (ΔI/I0) was used to show the sensing ability of those hosts. Hosts β-1 and γ-1 exhibit higher sensing ability for amines in a host solution of pH 5.90 than those in a host solution of Menzel buffer. It is probably caused by some hydrogen bonding between the carboxylic anion of the hosts and quaternary ammonium type guests.

Synthesis of bis dansyl-modified β-cyclodextrin liner trimer having multi-recognition sites and high hydrophobic environment

Abstract Fluorescent β-cyclodextrin (CyD) trimer linked with amine, which are (6A,6D-bis-deoxy-dansylamino-β-CyD)6-deoxy-bis-β-CyDs (β-1), has been synthesized in order to investigate their sensing ability for organic compounds such as bile acids. Host β-1 showed pure monomer fluorescence, exhibiting a decrement in fluorescence intensity on complexation of bile acid. The extent of fluorescence variation with a guest was employed to evaluate the sensing ability of β-1. The guest-induced variation in the fluorescence (ΔI) was used to describe the sensing ability of β-1. Host β-1 could detect ursodeoxycholic acid and chenodeoxycholic acid with remarkable sensitivities, although, could not detect deoxycholic acid and cholic acid. The behaviors of the appended moieties of β-1 during a host–guest complexation were studied by induced circular dichroism (ICD), fluorescence and absorption spectra and MM2-energy-minimized structure. The guest-induced variations in the absorption, fluorescence, and ICD intensity suggest that the appended moieties work as a hydrophobic cap to elevate binding ability, and this fact was supported by three-dimension MM2-minimized structure while a host–guest complexation occurred.

Selective chloromethylation of cavitand at the upper rim and induced fit type complexation with metal cations by new cavitands: Aza-crown-modified cavitands

Abstract Regioselective mono and dis-chloromethylation of cavitands have been prepared as an intermediate of a new cavitand derivative. Mono- and bis-aza-15-crown-5 modified cavitands ( 4 and 5 , respectively) have been obtained from mono- and bis-chloromethylated cavitands, respectively. The metal binding properties of native cavitand ( 1 ), 4 and 5 were studied by 1 H-NMR and UV-Vis spectroscopy.

Fluorescent Molecular Recognition and Sensing System of Bis-Dansyl Modified γ-Cyclodextrins

Flexible hosts, 6A,6B-; 6A,6C-; 6A,6D-; and 6A,6E-bis dansylglycine-modified γ-cyclodextrins (γ-1, γ-2, γ-3, and γ-4, respectively) have been synthesized as a sensing molecule for organic guests including terpenoids and bile acids. These host compounds show a pure monomer fluorescence whose intensity is decreased or enhanced upon addition of guest species. The value Δ I/I0, where I and I0 are fluorescence intensities in the presence and absence of a guest and Δ I is I0- I, was used as a parameter of sensitivity. These hosts exhibit highly sensitive and selective molecular recognition ability, particularly, for lithochoic acid, chenodeoxycholic acid, and ursodeoxycholic acid. The behaviors of the appended moieties of these hosts when host–guest complexation occurs are studied by induced circular dichroism (ICD) spectra and fluorescence spectral change on accommodation of a guest. The ICD pattern of these hosts alone or on accommodation of a guest is very similar, indicating that the behavior of the appended moieties are very similar. The guest-induced variations in the fluorescence or ICD intensity suggest that the appended moieties act as a hydrophobic cap that enables the cyclodextrin to form 1 : 1 host–guest complexes.

The Effect of Dansyl-Modified β-Cyclodextrin on the Chaperone Activity of Heat Shock Proteins

The effect of dansyl modified β-cyclodextrin (1)on the chaperone activity of heat shock proteins such as HSP70 and HSP90 hasbeen studied. The fluorescence intensity of 1 was decreased when HSP70 and HSP90 were added to the host solution. This phenomenon suggested that host–guest complexation was occuring. The binding constants of 1 were obtained using a 1:1 complex formation type equation by employing the guest-induced fluorescence variations. Host 1 exhibited a higher binding ability forHSP70 than for HSP90. The effects of 1 on the chaperone activity and degradation of HSP70 and HSP90 were studied by measuring the absorption of aggregation of citrate synthase (C.S.) and sodium dodecyl sulfate (SDS)polyacrylamide gel electrophoresis of trypsin degradation, respectively. Host1 can contribute to regulate C.S. aggregation andpromote trypsin degradation of HSP70 and HSP90.

Synthesis of a Selective Fluorescent Sensing System Based on γ-Cyclodextrin Modified with Pyrene and Tosyl on the Hetero Rims

The hetero-functionalized host bearing pyrene andtosyl moieties substituted at the lower and upper rims of cyclodextrin, namely,mono-3A-deoxy-3A-pyrenebutylamido-6X-O-mono-(p-toluenesulfonyl)mono-altro-γ-cyclodextrin(mixture :gamma; -1; X = A, B, C, D, E, F, G,or H), has been synthesized in order to investigate itsfluorescent sensing system for organic guests such as steroidsand terpenoids. This host showed pure monomer fluorescence, in which the host fluorescence increasedin intensity on accommodation of bile acids and terpenoids or decreased in fluorescence intensityupon addition of ketosteroids. The extent of fluorescence variation with a guest was employed to evaluatethe sensing ability of the host. The sensing parameter Δ I/I°, where I and I°are the fluorescence intensities in the presence and absence of a guest and Δ I is I - I°, was used to describe the sensing ability. The host detected ketosteroids with negative parameters, on theother hand, bile acids and terpenoids were recognized by the host with positive parameters. Thebehaviors of the appended moieties of the host during host–guest complexation were studied by induced circulardichroism (ICD) and fluorescence spectra. The host compound showed different patterns depending on theguest. The guest-induced variations in the ICD and fluorescent spectra suggest that the pyrene moietyacts to elevate the binding ability and the tosyl moiety plays a roll as a spacer to regulate thecyclodextrin cavity size.

Synthesis of γ-Cyclodextrin Pyrene-Labeled at the Hetero Rim and Its Use in Fluorescent Molecular Sensing

Fluorogenic active host labeled at the upper and lower rims of γ-cyclodextrin, namely, mono-3A-deoxy-3A-pyrenebutylamido-6X-O-mono-pyrenebutylate-mono-altro-γ-cyclodetrin (mixtureγ-1,X = A, B, C, D, E, F, G, or H), has been synthesized in order to investigate their host-guest complexation with steroidal compoundsusing fluorescence spectra. Monomer and excimer fluorescence was observed for mixture host. Inclusion of a guest molecule in the cyclodextrin cavity resultedin increased monomer fluorescence and decreased excimer fluorescence. The extent of monomerand excimer fluorescence variations ofmixture γ-1 with the guestwas used as an indication for the sensing ability. The guest inducedfluorescence changes were measured for 10-7 M solutions of mixtureγ-1.The values Δ I/I0, where I0 and I are fluorescence intensities in the absence and presence of a guest, respectively, and Δ I is I0 - I, were then used to describe the sensing ability.