3,14-Bis(p-nitrophenyl)-17,17-dipentyltetrabenzo[a,c,g,i]-fluorene: a new fluorophore displaying both remarkable solvatochromism and crystalline-induced emission.

A series of 17,17-dialkyl-3,14-diaryltetrabenzofluorenes were efficiently prepared by using Suzuki-Miyaura cross-coupling reactions of the corresponding 3,14-dibromo derivatives. Studies of the unique fluorescence properties of these compounds showed that they display intense blue to yellow fluorescence with high quantum yields in the solution state and blue to orange fluorescence with moderate quantum yields in the solid state. In addition, the fluorescence wavelength of the bis(p-nitrophenyl) derivative is remarkably solvent-dependent in a manner that correlates with the solvent polarity parameter E(T)(30). The results of density function theory calculations suggest that the intramolecular charge-transfer character of the HOMO-LUMO transition is responsible for the large solvent effect. Moreover, addition of water to a tetrahydrofuran (THF) solution of this compound leads to quenching of the yellow fluorescence owing to an increase in the solvent polarity. However, when the amount of water fraction exceeds 70%, a new fluorescence band appears at the same orange-red emission wavelength as that of the solid-state fluorescence. This observation suggests the occurrence of a crystallization-induced emission (CIE) phenomenon in highly aqueous THF.

Investigations into tie lines and solubility curves on phase diagrams in open-tubular capillary chromatography using ternary mixed-carrier solvents.

Open-tubular capillary chromatography using a ternary solvent mixture consisting of a water-hydrophilic-hydrophobic organic solvent as a carrier solution has been developed. When the ternary carrier solution is fed into the capillary tube, the carrier solvents are radially distributed and generate inner and outer phases in the tube. The outer phase functions as a pseudo-stationary phase in chromatography. In this study, investigations proceeded with reference to the tie lines and solubility curves on the phase diagram of the ternary mixed solvents. Model analytes, 1-naphthol and 2,6-naphthalenedisulfonic acid, were separated in this order with ternary water-acetonitrile-ethyl acetate solvent mixtures (organic solvent-rich solutions) that possessed various solvent compositions on the tie lines. In addition, fluorescence photographs of the dyes dissolved in the ternary solvents in the capillary tubes were observed with a fluorescence microscope-CCD camera system. It was found that the separation performance on the chromatograms and the phase formation observed in the fluorescence photographs were related to data provided through the tie lines and solubility curves on the phase diagram. The solvent compositions on the same tie line that gave different volume ratios of upper and lower phases in a vessel influenced the chromatographic separation, or the resolutions of the analytes, and also the inner and outer phase formation in the chromatography.

Consideration of the tube radial distribution of the carrier solvents in a capillary tube under laminar flow conditions and computer simulation.

When the ternary mixed solvents of a water-hydrophilic/hydrophobic organic solvent mixture are delivered under microspace under laminar flow conditions, the solvent molecules are radially distributed in the microspace, and generate a major inner phase and a minor outer phase. We call this fluidic phenomenon as the tube radial distribution phenomenon (TRDP). In this paper, phase formation in the TRDP was collectively considered based on experimental data, such as the inner and outer phase formation in a microchannel under laminar flow conditions, the phase diagram for the ternary mixed solvents, the solvent-component ratios required for the TRDP, and the phase transformation in a batch vessel above atmospheric pressure, which were mainly reported in our previous papers. Furthermore, the formation of inner and outer phases in a capillary tube was simulated with the two-component solvents mixture model of water and ethyl acetate. Phase formations in capillary tubes were expressed through computer simulations.