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Ternary polymer blends comprising miscible and immiscible components are examined to improve the mechanical properties of polyamide 6 (PA6) under humid and high-temperature conditions. Miscible polymers increase the glass transition temperature (Tg), owing to their strong inter-molecular interactions, while phase-separated immiscible polymers reinforce the physical properties of PA6 as filler materials. Ternary blends exhibit these combined miscible and immiscible component contributions. Thus, in this study, ternary blends comprising PA6, polyethylene terephthalate (PET, immiscible component), and phenol novolac (PN, miscible component) are prepared by melt mixing. The PA6 stiffness in the water-absorbed state is reinforced by PET. Moreover, the proposed PA6/PET/PN ternary blends exhibit higher Tg values and lower water absorption rates than those of the PA6/PET binary blend, owing to the PN contribution. The PET and PN contributions are achieved independently and can be controlled via the composition ratios of the component polymers. Multifaceted property tailoring is thus demonstrated.

Visible-light irradiation (λ < 600 nm) of commercially-available CdS in alcohol successfully promotes hydrogenation of azobenzene to hydrazobenzene with more than 95% selectivity. This is promoted by strong adsorption of azobenzene to the photoformed zerovalent Cd species adjacent to the surface S vacancies on CdS; this leads to efficient reduction to hydrazobenzene.

Colloidal suspensions of gold nanoparticles (AuNPs) in water can be prepared by heating water containing HAuCl4 with citric acid as reductant and surface stabilizing reagent. This thermal reduction method, however, promotes aggregation of the formed AuNPs, resulting in bimodal distribution of AuNPs. Here we report that UV (254 nm) irradiation of water containing HAuCl4 with citric acid at room temperature successfully reduces HAuCl4 and produces monodispersed AuNPs, while suppressing aggregation of the formed AuNPs. Changing the intensity of UV light or the amount of citric acid added successfully produces AuNPs with tunable sizes and narrow size distributions.

Tafenoquine (TQ), a fluorescent antimalarial drug, was used as a receptor for the fluorometric detection of hypochlorite (OCl−). TQ itself exhibits a strong fluorescence at 476 nm, but OCl−-selective cyclization of its pentan-1,4-diamine moiety creates a blue-shifted fluorescence at 361 nm. This ratiometric response facilitates rapid, selective, and sensitive detection of OCl− in aqueous media with physiological pH. This response is also applicable to a simple test kit analysis and allows fluorometric OCl− imaging in living cells.

Visible light absorption of plasmonic Au nanoparticles supported on semiconductor TiO2 leads to injection of their photoactivated “hot electrons (ehot−)” into the TiO2 conduction band. This charge separation facilitates several oxidation and reduction reactions. These plasmonic systems, however, suffer from low quantum yields because the Schottky barrier created at the Au–TiO2 interface suppresses ehot− injection. Here we report that Au nanoparticles supported on the anatase particles isolated from Degussa (Evonik) P25 TiO2 promote ehot− injection with much higher efficiency than those supported on other commercially-available TiO2 and catalyze aerobic oxidation with very high quantum yield (7.7% at 550 nm). Photoelectrochemical and spectroscopic analysis revealed that the number of Ti4+ atoms located at the Au–TiO2 interface is the crucial factor. These Ti4+ atoms neutralize the negative charge of the Au particles and create a Schottky barrier with narrower depletion layer. This facilitates efficient ehot− injection by “quantum tunneling” through the Schottky barrier without overbarrier energy. The ehot− injection depends on several factors, and loading of 2 wt% Au particles with 3.5–4 nm diameters at around room temperature exhibits the highest activity of plasmonic photocatalysis.

Quantitative determination of toxic cyanide anions (CN−) in biological samples is an important subject. We synthesized a naphthalimide–coumarin conjugate with a simple imine linker (1), which behaves as a fluorescent receptor for ratiometric quantification of CN−. It exhibits green naphthalimide fluorescence at 533 nm, originating from the excited-state intramolecular charge transfer (ESICT) from coumarin to naphthalimide fluorophores. Selective CN− addition to the imine linker affords an α-amino nitrile product. This suppresses ESICT and creates coumarin fluorescence at 444 nm and naphthalimide fluorescence at 533 nm originating from direct photoexcitation of the respective fluorophores. The emission intensity at 533 nm is maintained upon CN− addition and can be used as an internal standard for analysis. This ratiometric response enables self-calibrating CN− quantification based on the intensities of two emissions in solution and in cells. This facilitates rapid (within 3 min), selective, and sensitive ratiometric detection of very low levels of CN− (>1.8 μM).

We synthesized a pyrylium–coumarin dyad (1) and used it for colorimetric detection of cyanide anions (CN−) in aqueous media. The receptor itself exhibits a long-wavelength absorption band at 643 nm due to the strong intramolecular charge transfer (ICT) from the diethylaminocoumarin to the pyrylium moiety. Selective nucleophilic addition of CN− to the pyrylium ring triggers the ring cleavage rapidly (within 8 min). This suppresses the ICT and decreases the intensity of the 643 nm band, along with an appearance of a new shorter-wavelength band at 472 nm assigned to the π,π* transition of the diethylaminocoumarin moiety. This drastic absorption change (643 nm → 472 nm) facilitates ratiometric detection of CN− based on the intensities of these two absorption bands in the visible region and successfully detects CN− as low as 8 μM.

We synthesized an indanedione–coumarin dyad (1) and used it as an off–on type fluorescent receptor for rapid, selective, and sensitive detection of CN− in an aqueous mixture. The receptor itself shows very weak fluorescence from the coumarin moiety due to the photoinduced electron transfer (PET) from the photoexcited coumarin to the indanedione moiety. Selective nucleophilic addition of CN− to the β-carbon of the receptor suppresses the PET and results in strong fluorescence enhancement. The reaction mechanism was fully confirmed by 1H, 13C NMR, Job's plot, and FAB-MS analysis. The receptor successfully detects CN− as low as 25 μM within 20 min.

Photoirradiation (λ > 300 nm) of TiO2 loaded with Pd nanoparticles (ca. 2 wt%, 5 nm diameter) in water containing alcohols and azobenzene derivatives at room temperature successfully produces the corresponding secondary amines with high yields. This is facilitated via consecutive photocatalytic and catalytic reactions: (i) photocatalytic oxidation of alcohols (aldehyde formation) and reduction of azobenzenes (aniline formation); (ii) catalytic condensation of the formed aldehydes with anilines on the TiO2 surface (imine formation); and (iii) photocatalytic hydrogenation of the formed imines (secondary amine formation). This catalytic system successfully produces several kinds of secondary amines with >80% yields.

Photoexcitation (λ > 300 nm) of TiO2 loaded with Pt nanoparticles promotes selective hydrogenolysis of epoxides using alcohols as reducing agents.

An amino-substituted spirothiopyran, when added to an aqueous solution containing gold nanoparticles (AuNPs), promotes aggregation of AuNPs at room temperature in the dark. The sulfur atom of the spirothiopyran has high nucleophilicity due to the substitution of electron-donating amino groups and is bound to the AuNP surface via covalent Au–S binding. This promotes spontaneous spirocycle opening of the spirothiopyran and produces a positively charged indolinium moiety on the AuNP surface. This reduces electrostatic repulsion between the AuNPs and promotes their aggregation. Changing the amount of the spirothiopyran added successfully produces AuNP aggregates with tunable sizes (40–1300 nm) and narrow size distributions with standard deviation being less than 30%. This system therefore has potential to be a new simple method for self-assembly of AuNPs.

We synthesized an indolium–coumarin dyad (1) and its derivatives with –Cl (2), –N(CH3)2 (3), or –NO2 (4) substituent, and used them for fluorometric detection of cyanide anions (CN(-)) in aqueous media. All of the dyads exhibit fluorescence enhancement by CN(-) via a nucleophilic interaction of CN(-) with the indolium carbon atoms. Their fluorescence response and selectivity to CN(-), however, depend strongly on the substituents. Ab initio calculation and kinetic analysis were performed to verify the behaviors. Substitution of electron-withdrawing groups (2 and 4) increases the electrophilicity of the indolium carbon. This decreases the activation enthalpy for the nucleophilic interaction with CN(-) and facilitates rapid CN(-) sensing. Compound 4 with very high electrophilicity, however, also promotes nucleophilic interaction with OH(-) in the solution, resulting in decreased CN(-) selectivity. As a result of this, the –Cl-substituted compound 2 containing the indolium carbon with appropriate electrophilicity facilitates rapid (within 1 min) and selective CN(-) detection.

Platinum (Pt) nanoparticles with4 nm diameter loaded on graphitic carbon nitride (g-C3N4) by reduction at 673 K behave as efficient co-catalysts for photocatalytic hydrogen evolution under visible light (λ420 nm). This is achieved by strong Pt-support interaction due to the high temperature treatment, which facilitates efficient transfer of photoformed conduction band electrons on g-C3N4 to Pt particles.

Cyanine dyes with indolium-coumarin linkages exhibit selective fluorescence enhancement for cyanide anions (CN(-)) via the nucleophilic interaction of CN(-) with their indolium carbon atoms. This facilitates rapid (detection time: 1 min) and sensitive (detection limit: 0.4 μM) sensing of CN(-) in aqueous media.

Photocatalytic oxidation of cyclohexane (CHA) with molecular oxygen (O2) was carried out using WO3 loaded with Pt nanoparticles (Pt/WO3) under irradiation of visible light (λ > 420 nm). The Pt/WO3 catalysts promote oxidation of CHA and give rise to partial oxidation products such as cyclohexanol (CHA-ol) and cyclohexanone (CHA-one) with ca. 93% selectivity. Among the catalysts, Pt/WO3 with 0.2 wt% Pt shows the highest activity. The high selectivity for partial oxidation on Pt/WO3 is because subsequent photocatalytic decomposition of partial oxidation products is suppressed. In the Pt/WO3 system, the photoformed electrons on the conduction band of WO3 are consumed by a multi-electron reduction of O2 on the Pt particles (formation of H2O and H2O2), where a single-electron reduction of O2 is unfavored. This suppresses the formation of a superoxide anion (O2˙−) that promotes decomposition of CHA-ol and CHA-one and, hence, results in selective formation of partial oxidation products.

Phosphate particles of the selected rare earth metals have been prepared, using an emulsion liquid membrane [ELM, water-in-oil-in-water (W/O/W) emulsion] system, consisting of Span 83 (sorbitan sesquioleate) as surfactant and EHPNA (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) as extractant (cation carrier). The rare earth ions are extracted from the external water phase of the ELM system and are stripped into the internal water phase, containing phosphoric acid solution, to form the corresponding rare earth phosphate particles. The morphology and size of the particles are well-controlled by using the ELM system, and submicrometer-sized spherical phosphate particles are obtained, while micron-sized and irregular-shaped phosphate particles are obtained in homogeneous aqueous solutions. The resulting submicrometer-sized spherical particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and thermal analysis (TG–DTA). The characterization of La-based particles revealed that the fine particles obtained were of hexagonal structure, but their crystalline structure was changed to a monoclinic structure by calcination at 1373 K. Composite LaPO4:Ce3+,Tb3+ phosphor particles were then prepared by transporting La3+, Ce3+, and Tb3+ ions simultaneously, with the resulting particles showing good photoluminescence at 545 nm. In the ELM system, the size of the particles is able to be controlled in the range of 0.28 to 0.65 μm by changing the concentration of Span 83, whereas that in the homogeneous system is about 0.7 μm.

The incorporation of CdS nanoparticles, as prepared in reverse micellar systems, into silica matrices, via a sol–gel process, was investigated. The silica colloids containing CdS nanoparticles, CdS–COL, were prepared via the surface modification of CdS nanoparticles using 3-mercaptopropyltrimethoxysilane in reverse micelles. The recovery and dispersion of the nanoparticles was performed in an appropriate organic solvent, followed by a sol–gel process, using TMOS (tetramethyl orthosilicate) or TEOS (tetraethyl orthosilicate) in MeOH or EtOH solution. The size and morphology of the resulting CdS–COL was able to be controlled by changes in the silica source and the organic solvents. A CdS–COL stable against photoirradiation and heat treatment was able to be prepared which could be utilized as a photocatalyst for the generation of H2 from propan-2-ol aqueous solution. The silica bulk glass containing the CdS nanoparticles, CdS–GLA, was also prepared, such that the cut off wavelength of the glass could be precisely controlled by regulating the water content (Wo) for the reverse micellar system, during CdS preparation.

Y2O3 ∶ Eu3+ phosphor particles were obtained by calcination of composite Y–Eu oxalate particles prepared in emulsion liquid membrane (ELM, water-in-oil-in-water (W/O/W) emulsion) systems. In the ELM systems, composite Y–Eu particles could be prepared by transporting either Y3+ and Eu3+ ions or oxalate ions from the external water phase into the internal water phase, employing proper ELM systems, where bis(1,1,3,3-tetramethylbutyl)phosphinic acid (DTMBPA) or 2-methyl-2-ethylheptanoic acid (VA-10) was used as an extractant (cation carrier), or tri-n-octylamine (TNOA) was used as an anion carrier. These ELM systems were effective for preparing size (submicrometer) and morphology (spherical) controlled composite Y–Eu oxalate particles in the internal water droplets. The Y2O3 ∶ Eu3+ particles obtained by calcination of the composite oxalate particles showed photoluminescence at 614 nm.

Nano-CdS particles, as formed in reverse micelles, have been immobilized into polyurethane (PU), via surface-modification with 4-hydroxythiophenol or 2-mercaptoethanol, followed by polyaddition of ethylene glycol with toluenediyl 2,4-diisocyanate: the resulting composite, CdS-PU, obtained as powder, can be dissolved in organic solvents such as DMF and formed to make nano-CdS-containing transparent PU films, which show a quantum-size effect and are utilized for photocatalytic H 2 generation.

A resorufin–dinitrophenyl ether conjugate (1) shows emission enhancement for aromatic thiols in aqueous media with a neutral–basic pH, while being nonemissive for aliphatic thiols. This is achieved by two electrophilic sites with different local softness on compound 1; the respective sites selectively react with aromatic or aliphatic thiolate anions.

We synthesized a spiropyran–cholesterol conjugate (1) and studied its gelation and photochromic properties. The compound 1, when dissolved in carbon disulfide (CS2), forms a homogeneous gel at −40 °C due to the van der Waals interaction between the cholesterol moieties. UV or visible light irradiation of the CS2 sol or gel promotes a reversible change in color between yellow and purple without phase transition. This is promoted by reversible photoisomerization of the spiropyran moiety between the spirocyclic (SP) and the spirocycle-opened merocyanine (MC) form. In contrast, 1 forms a gel in benzyl alcohol (BA) at room temperature. The BA gel also exhibits a reversible color change upon UV/visible light irradiation, but the BA sol always shows a purple color due to the stabilization of the MC form by strong H-bonding interaction with solvents. The BA gel is successfully applied as a material for information storage, easily writable and erasable by light irradiation.

Photocatalytic hydrodenitrogenation of aromatic cyanides has been carried out on TiO2 loaded with Pd nanoparticles (Pd–TiO2) in the presence of ethanol as a hydrogen source. Photoirradiation of Pd–TiO2 at λ > 300 nm in ethanol containing aromatic cyanides successfully produces the corresponding toluene derivatives and triethylamine with almost quantitative yields. Photoexcited Pd–TiO2 catalysts promote oxidation of ethanol and reduction of protons, producing acetaldehyde and hydrogen atoms on the surface of Pd particles (H–Pd species). Aromatic cyanides undergo hydrodenitrogenation via consecutive reactions involving hydrogenation by the H–Pd species and condensation with aldehydes. The catalytic activity strongly depends on the amount of Pd loaded. The catalyst containing 2 wt% Pd, with a relatively low Schottky barrier height at the Pd–TiO2 heterojunction and a large number of surface Pd atoms, exhibits the highest denitrogenation activity.

TiO2 particles partially coated with WO3 (WO3/TiO2) were used as photocatalysts for selective oxidation of toluene to benzaldehyde with molecular oxygen (O2) under photoirradiation at λ > 300 nm. The catalysts loaded with 8–10 wt% WO3 exhibit very high oxidation activity and produce benzaldehyde with ca. 50% selectivity, which is the highest selectivity among the photocatalytic systems reported so far. This is achieved because subsequent photocatalytic decomposition of the formed benzaldehyde is suppressed on the catalysts. On the photoactivated WO3/TiO2, the exposed TiO2 surface behaves as the oxidation site, whereas the WO3 surface is much less active for oxidation. The WO3 loading decreases the amount of benzaldehyde adsorbed onto the TiO2 surface. This thus suppresses photocatalytic decomposition of benzaldehyde on the TiO2 surface, resulting in high benzaldehyde selectivity. The WO3/TiO2 catalyst successfully promotes side-chain oxidation of several kinds of alkyl-substituted aromatics and selectively produces aldehydes and ketones.

A spiropyran-amide-dipicolylamine linkage behaves as a colorimetric receptor for selective Co(2+) sensing in aqueous media under UV irradiation. This is promoted by strong coordination of Co(2+) with amide oxygens of the receptors and efficient photoisomerization of the spiropyran moieties.

A boradiazaindacene (BODIPY) derivative containing a simple NO bidentate ligand shows a Cu(2+)-selective fluorescence in aqueous media. This is promoted via a coordination of Cu(2+) followed by oxidative dehydrogenation of an amine moiety, leading to a formation of a fluorescent Cu(+)-Schiff base complex.

A novel desulfurization process for light oil, based on N-tosylsulfimide formation by the reaction of sulfur compounds with chloramine T (sodium N-chlorotoluene-p-sulfonamide), has enabled deep desulfurization at ambient temperature.

Thermally-induced isomerization of spiropyran derivatives in aqueous media has been studied. The colorless spirocyclic (SP) forms of spiropyran derivatives are isomerized to colored merocyanine (MC) forms even in dark conditions at elevated temperature. Equilibrium, kinetic, and deuterium experiments reveal that the thermal SP → MC isomerization is due to the stabilization of MC form by a hydrogen bonding interaction with water molecules. This leads to the ground state energy of the MC form decreasing to lower than that of the SP form, resulting in SP → MC isomerization. The thermal isomerization property is applicable to a rough indication of solution temperature. The spiropyran derivatives, when dissolved in aqueous media under irradiation of visible light with an appropriate light intensity, demonstrate an increase in MC absorbance with a rise in temperature. The absorption response occurs reversibly regardless of the heating/cooling sequence. The spiropyran derivatives therefore have a potential for colorimetric temperature indication.

Molecularly imprinted polymers containing a photosensitizer, rose bengal (RB), were synthesized via a polymerization of methacrylic acid (MAA) as a functional monomer and chlorophenols as template molecules. The polymeric sensitizers promote selective oxidation of target chlorophenol in water with molecular oxygen under visible light irradiation (λ > 530 nm). This is due to the selective attraction of the target substrate onto the molecular recognition site on the polymer followed by efficient oxidation of the substrate by a singlet oxygen produced by the photoexcited RB units located in the vicinity of the recognition site.

A coumarin-thiourea conjugate (1) behaves as a highly selective fluorescent probe for Hg(2+) in aqueous media. The probe 1 shows selective and quantitative fluorescence decrease upon Hg(2+) addition in aqueous media with a broad pH range, 2-12. Ab initio molecular orbital calculations reveal that the fluorescence decrease of 1 upon Hg(2+) addition is promoted by a Hg(2+)-induced desulfurization of the thiourea moiety, leading to a decrease in an intramolecular charge transfer (ICT) character of the excited-state coumarin moiety.

Photocatalytic oxidation of cyclohexane (CHA) with molecular oxygen has been performed with hydrophobic Cr–Si mixed oxides as a catalyst under visible light irradiation (λ > 400 nm). The Cr–Si catalysts with highly dispersed chromate species were prepared by hydrolysis of tetraethyl orthosilicate (TEOS), organoalkoxysilane (1,2-bis(triethoxysilyl)ethane: BTESE), and Cr(NO3)3 followed by calcination. All of the Cr–Si catalysts promote partial oxidation of CHA to cyclohexanol (CHA-ol) and cyclohexanone (CHA-one) with high selectivity (>99%). Among the Cr–Si catalysts prepared with different TEOS and BTESE compositions, the catalyst prepared with 10% BTESE demonstrates the highest catalytic activity. The CHA vapor adsorption and electron spin resonance analysis reveal that the enhanced catalytic activity is due to the increased hydrophobicity of the catalyst surface, which enhances the access of CHA to the excited state chromate species.

Nano-CdS particles, formed in reverse micelles containing ethylene glycol, have been immobilized in polyurethane, via an in situ polymerization of ethylene glycol with hexamethylene diisocyanate: the resulting composite can be utilized as a photocatalyst and processed to make a transparent film.

An indole-azadiene conjugate (1), synthesized by facile one-step condensation, behaves as a highly selective probe for detection of fluoride ion both in colorimetric and fluorometric analyses. The probe 1 shows F(-)-selective color change from colorless to yellow and appearance of green fluorescence. 1H NMR analysis and ab initio calculation reveal that the F(-)-induced colorimetric and fluorometric responses of 1 are simply driven by hydrogen bonding interaction between the indolic NH protons and F(-).

A polymeric photosensitizer, poly(NIPAM-co-RB), consisting of N-isopropylacrylamide and rose bengal units, demonstrates a temperature-controlled changeable oxygenation selectivity by singlet oxygen in water.

A visible light-induced desulfurization process for light oil, effected by electron-transfer photooxygenation and liquid–liquid extraction, allows the deep desulfurization of light oil under moderate conditions and without hydrogen.

Cr-Si binary oxide prepared by a sol-gel method, when activated by visible light, catalyses highly selective oxidation of cyclohexane to cyclohexanone with molecular oxygen.

Simple polyamines, L1-L3, bearing anthracene and benzophenone units at the respective ends, behave as a fluorescent pH sensor applicable to wide-range pH detection.

A simple molecule, L, diethylenetriamine bearing anthracene fragments at both ends, behaves as a fluorescent molecular logic gate with "multiply-configurable dual outputs", capable of demonstrating five different logic functions operated by proton (H+) and transition metal cations (Mn+) as inputs.

Highly selective photocatalytic epoxidation of olefins proceeds on Ti-containing silica with tetrahedrally coordinated Ti-oxide species with molecular oxygen and a simple addition of MeCN.

The electrochemical behaviour of polyaniline (PAn) in weak acid solutions such as pH 4 has been studied. It has been found that PAn gives a stable redox reaction involving electrolyte anions in a limited potential region, whereas it loses its electrochemical activity by being oxidized at more anodic potentials where deprotonation preferentially takes place. Detailed mechanisms of the redox and the inactivation reaction of PAn in weak acid solutions are discussed.