Carbazole-based donor-acceptor compounds 1,2-dicyano-trans-1,2-bis-4-(carbazolyl)phenylethylene (1) and 1,2-dicyano-trans-1,2-bis-4-(3,6-di-tert-butylcarbazolyl)phenylethylene (2) were synthesized. 1 and 2 show negative solvatochromic absorption behavior, but show both positive and negative solvatochromic behavior in the fluorescence spectra. In a water/THF mixture, 1 as well as 2 aggregate into 50-150 nm nanoparticles. The emission of nanoparticles of the new types of fluorescent organic nanoparticles (FONs) 1 and 2 is much higher than that of either 1 or 2 in solution.
Suitably substituted ethynylphenyl carbazoles (PBM and PPM) form stable fluorescent organic nanoparticles. The emission of the nanoparticles can be reversibly switched on/off in the blue-green and orange-red regions by a change in the ratio of the tetrahydrofuran/water system used in their preparation. The size of the nanoparticles was found to be dependent on the solvent ratio, and the emissions were significantly red-shifted compared to those of dilute solutions of PBM and PPM in tetrahydrofuran. This is attributed to the formation of intermolecular charge transfer complexes in the nanoparticle state. The application of the nanoparticles as a chemical vapor sensor has been suggested.
A comparative study of suitably functionalized, highly soluble tetraceno[2,3-b]thiophenes (1-3) and pentacenes (4-6) that show higher photoxidative stability than that of unfunctionalized corresponding acenes is reported. The absorption and emission of 1-3 (Amax = 624-656 nm, lambda max = 634-672 nm, PhiF approximately 10%) and 4-6 (Amax = 672-704 nm, lambda max = 682-718 nm, PhiF approximately 10%) were found to be systematically red-shifted by the substitution in the order of the tert-butylethynyl < triisopropylsilylethynyl < phenylethynyl groups. The oxidation potentials of these compounds were similar (E1/2 approximately 0.70 V), except for 4, which showed lower oxidation potential (E1/2 approximately 0.63 V).
Principal component regression (PCR) was used to develop calibration and prediction models for determination of mineral content of complex mineral mixtures by utilizing attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra. The typical constituents of oil shale such as dawsonite, nahcolite, quartz, dolomite, illite, albite, analcime, and kerogen were used to prepare samples to record mid-infrared (IR) spectra. The specified values of dawsonite, nahcolite, quartz, dolomite and kerogen were in good agreement with measured data.
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