Encapsulation and Enhanced Luminescence Properties of IrIII Complexes within a Hexameric Self‐Assembled Capsule

Encapsulation and luminescence studies of [Ir(ppy)₂(bpy)]Cl (ppy=2‐phenylpyridinate, bpy=2,2′‐bipyridine) within a hexameric resorcinarene capsule are reported. One Ir^III complex cation was encapsulated within the capsule, as demonstrated by NMR and dynamic light scattering (DLS) studies. The emission color of the Ir^III complex was drastically changed from orange to yellow by encapsulation, in contrast with the lack of significant changes in the absorption spectrum. The hexameric capsule effectively hampers the non‐radiative pathway to increase both the luminescence quantum yield and the exited state lifetime. The luminescent properties of the encapsulated Ir^III complex depend on the ratio of Ir^III complex to the resorcinarene monomer as well as the concentration of resorcinarene monomer owing to the reversible process of self‐assembly of the hexameric capsule. Quenching experiments revealed that the Ir^III complex in the capsule was effectively separated from quenchers.     

Ultrasound-assisted ozone bleaching of cotton

In this study, the effects of ultrasound on ozone treatment processes for bleaching cotton fabrics were investigated and compared with the conventional hydrogen peroxide bleaching process (60 °C over 90 min). Two ultrasonic + ozone treatments of cotton fabric samples were carried out: (1) ozone in an ultrasonic homogenizer (UH) and (2) ozone in an ultrasonic bath. Ozone dosages, temperature and time variations were determined with both ozone-ultrasonic bleaching processes. Whiteness, yellowness, weight, tensile strength properties, FTIR (ATR) spectra and visual appearance, via scanning electron microscopy of treated cotton fabrics as well as chemical oxygen demand (COD) of bleaching effluents, were investigated. It was concluded that the ozone + UH process, conducted for 30 min at 30 °C, produced closely equivalent values of cotton fabric whiteness and yellowness to the classic peroxide bleaching process, with slightly less weight loss, dramatically less COD in the process effluent (29 mg/l for ozone-UH vs. 4,316 mg/l for classical peroxide treatment), and without causing any adverse and/or detrimental effects on loss of fabric strength or elongation of the cotton fabrics. The ozone-UH process also leads to time and energy savings with much less environmental impact. Consequently, the combination of ozonation plus UH carried out at 30 °C over 30 min can be used successfully for cotton bleaching instead of the classic hydrogen peroxide bleaching process.     

Synthesis and γ-radiolysis of 2′-deoxy-5-fluorouridine and 5-fluorouridine derivatives

Seventeen compounds having a variety of substituents at the 3- and 5′-positions of 2′-deoxy-5-fluorouridine (5-FUdR) and 5-fluorouridine (5-FUR) were synthesized, and their γ-radiolysis in aqueous solutions were studied. The compounds having thioureido (RNHCSNH, R  H, PhCH₂, acyl) and thiocarbonylamino (XCSNH, X  PhCH₂S, PhO) groups at the 3-position of 5-FUdR were efficiently cleaved to give 5-FUdR with high G values upon γ-irradiation of their aqueous solutions. The active species for these cleavage reactions were hydrated electron (e⁻ _aq), H^• and HO^•. However, the compounds having a dimethylsulfoxyimino group at 3-position of 5-FUdR and 5-FUR afforded 5-FUdR and 5-FUR only under the radiolysis conditions where e⁻ _aq becomes a principal active species. The compound having a 2-benzoylthiazoylthiocarbonylamino group at the 3-position of 5-FUdR showed the highest reactivity toward HO^.. The mechanisms of these γ-radiolysis reactions are discussed. The examination of anticellular activities of γ-irradiated compounds having a thiocarbonylamino group at the 3-position of 5-FUdR toward murine Sarcoma 180 cells revealed that these compounds may be utilized as a candidate for a radiation-induced drug (RID).     

Amphidinolide Y, a novel 17-membered macrolide from dinoflagellate Amphidinium sp.: plausible biogenetic precursor of amphidinolide X

A novel cytotoxic 17-membered macrolide, amphidinolide Y (1), has been isolated from a marine dinoflagellate Amphidinium sp., and it was elucidated to exist as a 9:1 equilibrium mixture of 6-keto- and 6(9)-hemiacetal forms (1a and 1b, respectively) on the basis of 2D NMR data and chemical means. The feeding experiments with (13)C-labeled acetates suggested that amphidinolide Y (1) may be a biogenetic precursor of 16-membered macrodiolide, amphidinolide X (2).     

Asymmetric total synthesis of rhinacanthin A

Starting from a reduced lapachol compound, the total synthesis of rhinacanthin A in both racemic and enantioenriched forms is achieved in eight steps without forming any undesired β-lapachone derivatives. For the synthesis of enantioenriched rhinacanthin A, the introduction of the asymmetric center was carried out by using the catalytic asymmetric epoxidation of an unfunctional trisubstituted olefin using Shi’s epoxidation diketal catalyst. The acidic treatment of a derived enantioenriched epoxynaphthol and the following CAN oxidation afforded the target molecule with high enantiomeric purity.     

Synthesis of polyhedral particles by dispersion polymerization in supercritical carbon dioxide

The novel synthesis of polyhedral particles was attained by the dispersion polymerization of styrene in supercritical carbon dioxide using a polydimethylsiloxane-based macroazoinitiator as a precursor of the surfactant. The macroazoinitiator, VPS-1001, composed of poly(dimethylsiloxane) and 6-8 molecules of the azo groups served as a precursor of the surfactant for the dispersion polymerization by azobisisobutylonitrile as an initiator to produce 0.8-4 μm polyhedral particles. The size of the particles decreased as a result of increasing the VPS-1001 concentration. Too high a concentration of VPS-1001 caused coagulation of the particles. A decrease in the temperature increased the particle size and size distribution, while a decrease in the pressure produced particles with nonspecific shapes. An increase in the stirring rotation speed tended to increase the size and size distribution. However, too high a speed of rotation also caused coagulation of the particles.     

Pipette tip biosensors for bacterial double-stranded DNA using bioluminescence induced by zinc finger luciferase

The authors describe a pipette type of biosensor for detecting target genes and using a zinc finger protein fused to luciferase (ZF luciferase). The ZF protein binds to a specific DNA sequence, and the target double-stranded (ds) DNA can be detected by monitoring the enzymatic activity of ZF luciferase. A small avidin-immobilized reaction plate is placed on a plastic pipette tip (referred to as Biologi tip). The dsDNA detection procedures are carried out by using a programmable dispensing robot equipped with a photodetector. These procedures include (a) the aspiration of an analyte to capture the biotinylated target dsDNA (a product of a polymerase chain reaction) on the small reaction plate inside the pipette tip, (b) the introduction of ZF luciferase and luciferin into the pipette tip, and (c) migration of the pipette tip to the detection port to measure bioluminescence on the small reaction plate. The emission originating from luciferase activity is observed on the reaction plate containing immobilized biotin-tagged target dsDNA, whereas plates containing non-target or biotinylated single-stranded DNA only do not yield a signal. The intensity of emission increases proportionally to the concentration of dsDNA, and the detection limit of the target dsDNA is as low as 62 pM. An actual genomic DNA sample from Escherichia coli O157 was successfully detected by this automatic analyzer using the Biologi tip equipped with a reaction plate. This indicates that this system has a large potential for practical applications, including in particular point-of-care analyses in hygiene control, food safety testing, and clinical diagnosis.

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Graphical abstract A pipette-type biosensor was developed to detect target genes using a luciferase-fused zinc finger protein, where a small NeutrAvidin-immobilized reaction plate was placed on the tip, and the biotinylated target double-stranded DNA was detected by monitoring the bound luciferase activity.

     

Synthesis of boradiazaindacene-imidazopyrazinone conjugate as lipophilic and yellow-chemiluminescent chemosensor for superoxide radical anion

As a chemiluminescent chemosensor that emits yellow light on reacting with a superoxide radical anion (O₂⁻) and has a lipophilic character, a 6-phenylimidazo[1,2-a]pyrazin-3(7H)-one derivative possessing a boradiazaindacene (BODIPY) at the para position of 6-phenyl (1) was synthesized. The lipophilicity of 1 was investigated by reversed-phase liquid chromatography, and its log P_ow value was found to be 3.57. This value was much higher than that of 2-methyl-6-(4-methoxypheyl)imidazo[1,2-a]pyrazin-3(7H)-one (MCLA, log P_ow=1.19) and 6-[4-[2-{N′-(5-fluoresceinyl)thioureido}ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (FCLA, log P_ow=−0.08), and it was comparable to that of benzenoid hydrocarbons. The O₂⁻-induced chemiluminescence of 1 was investigated using the hypoxanthine/xanthine oxidase system as the source of O₂⁻, and as a result, yellow emission was observed. The maximum wavelength was observed at 542 nm, and it was longer than that of FCLA.     

Nitroxide-mediated photo-living radical polymerization of methyl methacrylate using (4-tert-butylphenyl)diphenyl-sulfonium triflate as a photo-acid generator

The photo-living radical polymerization of methyl methacrylate (MMA) was performed at room temperature using (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) (r-AMDV) as the initiator, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) as the mediator, and (4-tert-butylphenyl)diphenylsulfonium triflate ( ^t BuS) as the photo-acid generator. The livingness of the polymerization was confirmed on the basis of linear increases in the ln([MMA]₀/[MMA]_t) vs. time and in the molecular weight vs. the conversion. The molecular weight distributions of the resulting polymers were around 1.45. The polymerization rate was dependent both on the ^t BuS/MTEMPO and MTEMPO/r-AMDV molar ratios. Furthermore, it was found that the polymerization had a photo-latency because the polymerization was retarded by the interruption of the irradiation; however, it was accelerated again by further irradiation without deactivation of the growing polymer chain ends.