Furan fluorescence: 5‐Hydroxymethylfurfural, available from biomass, is efficiently oxidized to 2,5‐diformylfuran by using molecular oxygen, under mild conditions. The oxidation is catalyzed by Cu(NO3)2/VOSO4. The renewable, rather than petroleum‐based, furan dialdehyde is used for the synthesis of a fluorescent material.

No abstract

A π-conjugated polymer with 2,5-bis(benzoxazol-2′-yl)benzene-1,4-diol fluorene units is synthesized by using a Suzuki-Miyaura coupling reaction (M w ) 1.3 × 10 4 ; PDI ) 1.8). The polymer exhibits UV-vis absorption, λ max ≈ 421 nm, and fluorescence, λ max ≈ 616 nm. The observed large Stokes shift (∼200 nm) is attributed to an excited-state intramolecular proton-transfer process. The addition of anionic species (hydroxide, fluoride, and acetate) causes the absorption λ max to be red-shifted to 510-540 nm and the fluorescence quantum efficiency to be increased by a factor of ∼20. Through the study of a model compound, the structure of the anion complex is determined to be deprotonated monoanion, as evidenced from the Benesi-Hildebrand plot and electron-spray mass spectrometry. On the basis of a large spectral response in absorption and significant fluorescence enhancement, the material could be useful for dualchannel detection of anions.

Furan-based copolyesters were synthesized via polytransesterification of 2,5-furandicarboxylic acid (FDCA) with ethylene glycol (EG) and 1,4-butylene glycol (BG). The composition and thermal properties of the obtained copolyesters were characterized in detail by 1 H NMR and elemental analysis, differential scanning calorimeters (DSC) and thermogravimetric analysis (TGA). The 1 H NMR results showed that the ethylene segment content was consistently lower than that of butylene in the obtained copolyesters in comparison with the comonomer feeds. The reactivities of EG and BG with FDCA were intensively investigated. On the basis of kinetic studies, EG was found to be less reactive than BG. The thermal properties of the obtained copolyesters could be adjusted by variation of the EG/BG molar ratios in the copolyesters. Experimental sectionMaterials 1,4-Butylene glycol (99%) was purchased from Aldrich. Ethylene glycol (99%), titanium(IV) n-butoxide (99%), 1,2-dichlorobenzene

Pyrophosphate (PPi) is a biologically important target. A binuclear system 3•2Zn is found to selectively recognize PPi, leading to a ratiometric fluorescent sensor at pH 7.4 in water. The binding event triggered a large fluorescence response (∼100 nm bathochromic shift) by turning on the excited state intramolecular proton transfer (ESIPT). Detection of PPi released from a PCR experiment indicated that this new probe could be a useful tool in bioanalytical applications.

An NIR-emitting probe (λem~700 nm) with a large Stokes shift (Δλ≈234 nm) is synthesized by using excited-state intramolecular proton transfer (ESIPT). The phenolic proton, which controls ESIPT, acts as a switch to give strong fluorescence at pH≈5. The probe can selectively show lysosome organelles, therefore leading to a lysosome probe without exhibiting “an alkalinizing effect”.

Wrapping of a single-walled carbon nanotube (SWNT) was examined by using a poly[( m-phenylenevinylene)- alt-( p-phenylenevinylene)] (PmPV) derivative. The polymer's intrinsic ability in forming a helical conformation was found to play an essential role in the separation of nanotubes. Among about 15 tubes present in the pure SWNT (HiPcoTM) sample, the polymer was found to selectively pick up the tubes (11,6), (11,7) and (12,6), which correspond to tube diameters of 1.19, 1.25 and 1.24 nm, respectively. The SWNTs of smaller diameters were held loosely by the PmPV, and were gradually dropped out under centrifugation. The suspension solution prepared from the SWNT and PmPV was not permanently stable, with precipitation occurring after a few weeks. Irradiation in the UV-vis region exhibited a catalytic effect to shorten the precipitation time to hours. Those tubes, which were held loosely by PmPV, were quickly separated from the suspension during the irradiation process.

A derivative of poly[(m-phenylenevinylene)-alt-(p-phenylenevinylene)] ( 7) has been synthesized via the standard Wittig condensation to investigate the effects of m-phenylene on the physical properties of PPVs. The polymer synthesized has a molecular weight of about 20 000, corresponding to a number-average degree of polymerization of about 41. A model compound, 1,4-distyryl-2,5-dihexyloxybenzene (9), has also been synthesized to evaluate the effectiveness of π-conjugation interruption at m-phenylene. Comparison of photoabsorption and emission characteristics between 7 and 9 indicates that the presence of m-phenylene effectively interrupts the conjugation in PPV, allowing precise color control in the fully π-conjugated polymers. 1 H NMR is found to be a convenient tool to characterize the cis/trans-olefins in the polymer. The PL quantum yield of 7 is quite high in both solution and solid states (0.6-0.8), suggesting potential applications of the material in various electrooptical devices.