Cyclodextrin rotaxanes and polyrotaxanes.
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Crystallography, X-Ray↗
Biomedical subjects
Bao-Hang Han
Publications and source records attributed to Bao-Hang Han.
Phosphorescence quenching of dyes adsorbed to silica thin-layer chromatography plates.
We describe photoluminescence (PL) quenching experiments by oxygen for a series of transition metal dyes adsorbed to commercial silica thin-layer chromatography plates. These TLC plates have been used by others as rapidly responding PL pressure sensors. The quenching kinetics show interesting differences from the behavior of the same dyes adsorbed to the more well-defined surfaces of SBA-15 mesoporous silica particles adsorbed to a thin layer-by-layer polymer film as reported in Chem. Mater. 2005, 17, 3160. The pore size and the pore size distribution are much larger for the TLC silica than for the mesoporous silica. On the TLC silica, the dye PL decay profiles show smaller deviations from an exponential form. One sees larger differences between the intensity and lifetime Stern-Volmer plots, and most surprisingly, the dyes on the surface of the TLC silica are about three times more sensitive to quenching by oxygen.
Journal Article↗
Simple synthesis route to monodispersed SBA-15 silica rods.
A simple, flexible, reproducible, high-yielding (ca. 100%) synthesis of hexagonally facetted SBA-15 straight rods with uniform sizes (ca. 1.5 x 0.4 mum) under static conditions without using inorganic salts is provided. This method affords rodlike particles with temperature-dependent pore sizes ranging from 5.8 to 12.5 nm but with similar external dimensions. This work shows that in order to prepare short monodispersed SBA-15 rods, (i) the absence of stirring is essential, (ii) the temperature of the first stage should not exceed 60 degrees C, and (iii) addition of inorganic salts is not required.
Journal Article↗
Direct preparation of nanoporous carbon by nanocasting.
Nanoporous carbon with narrow pore size distribution was prepared via a nanocasting technique by direct carbonization of cyclodextrin-silica organic-inorganic hybrid composite. The obtained carbon exhibited very high BET surface area and high pore volume.
Journal Article↗
In situ cyclodextrin-based homogeneous incorporation of metal (M = Pd, Pt, Ru) nanoparticles into silica with bimodal pore structure.
In situ cyclodextrin (CD)-based homogeneous incorporation of metal (M = Pd, Pt, Ru) nanoparticles into silica with bimodal pore structure has been realized by utilizing the self-assembly aggregation and inclusion capability of the CDs.
Catalysis↗
Molecular Recognition Study on Supramolecular Systems. 20. Molecular Recognition and Enantioselectivity of Aliphatic Alcohols by L-Tryptophan-Modified beta-Cyclodextrin.
L-Tryptophan-modified beta-cyclodextrin (L-Trp-beta-CD) has been synthesized and its molecular recognition behavior investigated through fluorescence and circular dichroism spectrometry, as well as fluorescence lifetime measurement in the presence and absence of various alcohols as guest molecules. Employing the indolyl group as a spectral probe, spectrofluorometric and spectropolarimetric titrations have been performed in aqueous phosphate buffer solution at pH 7.20 to calculate the complex stability constants for 1:1 inclusion complexation of L-Trp-beta-CD with several series of alcohols at 25 degrees C. The results obtained indicate that L-Trp-beta-CD can recognize not only size/shape and hydrophobicity but also the enantiomeric and geometrical isomers of the guest alcohols, showing a 230-fold molecular selectivity (13.5 kJ mol(-)(1)) for 2-adamantanol over cyclopentanol among the cyclic alcohols examined. Moderate enantiomeric selectivities of 1.2 and 1.9 for (-)-isomers of borneol and menthol, respectively, and geometrical selectivity of 2.0 for geraniol over nerol have also been observed.
Journal Article↗