•A new kind of fluorescein-based ion sensor was synthesized.•The sensor could be a good probe for Ca2 + and Mg2 + determination.•Two-step binding events were observed in the sensing process.In the present work, a new kind of fluorescein-based chemosensor L was designed and synthesized to selectively recognize Ca 2+ or Mg 2+ over other competing ions. The chemosensor showed “off–on” fluorescent and color changes upon the addition of Ca2 + and Mg2 +. The dynamic binding events with the formation of 1:1(L/M) and 1:2(L/M) complexes were examined. The cation-driven conformation changes of L were understood and proposed rationally by the UV–vis, FL, and 1HNMR titrations. By this allosteric effect, Ca2 + and Mg2 + could be selectively recognized with the 1:2 stoichiometry by fluorescent changes, which were different from other known reports on chemosensors that the host-cation complexion was exploited for controlling chromophore interaction as the model of signaling.

In this paper, half-tubes, micro-wires and ribbons were constructed in a simple cholesterol-based organogel by varying polar gelation solvents such as acetonitrile, isopropanol, and ethanol. All of them showed hydrophobic surfaces with water contact angles more than 140°. Moreover, the interlaced micro-wires obtained from isopropanol were of 500 μm in length, which could hold a water droplet even at an 80° incline. The formation and the characterization of the half-tube were followed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-Ray diffraction (XRD) and UV-vis spectra revealed that the aggregates were constructed by dimers of the molecules with H aggregates in the layer structure. It was proposed that hydrogen bonding, hydrophobic interactions, π–π stacking as well as solvent molecules played an important role in the assembly.