Three-dimensional high-performance liquid chromatography based on time-resolved laser fluorimetry

Microcolumn high-performance liquid chromatography is used for trace determinations of polynuclear aromatic hydrocarbons. The detector is a laser fluorimetric system with subnanosecond time resolution. The detection limit is 210 fg for perylene. In chromatography, the fluorescence decay curves are measured successively as the sample elutes by a microcomputer-controlled data-processing system. A three-dimensional chromatogram, in which retention times and delay times are displayed, is constructed after sample elution. A real sample extracted from airborne particulates is measured, and perylene, benzo(a)pyrene, and benzo(ghi)perylene are shown to be present.     

Thermally switchable polyrotaxane as a model of stimuli-responsive supramolecules for nano-scale devices

A polyrotaxane consisting of many β-cyclodextrins (β-CDs) and a triblock copolymer of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) capped with bulky end-groups was synthesized as a model of stimuli-responsive supramolecules for nanoscale devices. The polyrotaxane was reversibly soluble-insoluble in water in response to temperature. This was achieved through the assembled and dispersed states of β-CDs along the block copolymer. It is considered that intermolecular hydrogen bondings of β-CDs, as well as the PEG segment length of the copoloymer, are predominant factors for regulating such thermally switchable behavior of the polyrotaxane.     

Supramolecular network formation through inclusion complexation of an α‐cyclodextrin‐based molecular tube

The supramolecular network formation through inclusion complexation between α‐cyclodextrin‐based molecular tube (MT) and poly(ethylene oxide) monocetylether‐graft‐dextran (5C₁₆PEO‐g‐Dex40) was demonstrated. From isothermal titration calorimetric (ITC) measurement, it was confirmed that MT formed an inclusion complex with two C₁₆PEO side chains in 5C₁₆PEO‐g‐Dex40. From viscosity measurements, the specific viscosity of the solution containing MT and 5C₁₆PEO‐g‐Dex40 was much larger than that containing 5C₁₆PEO‐g‐Dex40. It is considered that MT participates in the supramolecular network formation of 5C₁₆PEO‐g‐Dex40 through inclusion complexation with two C₁₆PEOs grafted to independent Dex40s.