Seung-Rim Shin

Synthesis and Characterization of New Liquid Crystals containing a Non-Activated Indolinobenzospiropyranyl Group. Part 4*[1]

A series of new liquid crystalline compounds, 1′,3′,3′-Trimethylspiro[2H-1-benzopyran-2,2′-indolin]-6-yl 4-(4′-alkoxyphenylazo)benzoate, SP-APAB 1a ∼ 1f, has been synthesized. Their liquid crystallines were subjected to thermal analysis on a differential scanning calorimeter (DSC), to texture of phases on a polarizing microscope and to phase transition on an X-ray diffraction and electro-optical measurement. Most of compounds examined exhibit monotropic nematic and SmA liquid crystal phases on cooling from isotropic liquid. Suprisingly, SP-APAB 1c is shown to exhibit monotropic SmC phase in addition. X-ray diffraction study of the layer spacing confirmed that there was a layer spacing in the range of two theta from 2.25 to 2.45 Å on the temperature near the phase transition from SmA to SmC.

Synthesis of Rhodamine-based Chemosensor and Determination of Spectral Properties

A rhodamine-based fluorescent chemosensor (Rh6G-2HC) was synthesized easily by a one-step condensation reaction. The structure was characterized using NMR, MS and EA spectroscopies. As soon as Cu2+ was added into the chemosensor solution, a color change from colorless to pink color was observed, and a considerable change in the absorption and fluorescence spectra. However, no spectral changes were indicated for other heavy metals such as Ag+, Zn2+, Cd2+, and Co2+. In order to provide a more detailed metal sensing performance, the optical and structural properties for the Cu2+ sensing effect were investigated using UV-Vis, fluorescence and H-NMR spectroscopies.