[ 4 ] Study On Synthesis And Properties Of Aromatic Sulfonic Acid Sodium Salt

In this article p-sulfonated calix[4]arene was synthesized by three steps using p-tert-butyl-phenol as an original reactant. The UV-vis spectrum, FTIR spectrum, HNMR and electrochemical methods were used to confirm them. The maximum UV-vis absorption of p-sulfonated calix[4]arene located at 283 nm. The molar absorbance coefficient of p-sulfonated calix[4]arene was measured as 5.99×10 M-1.cm-1. In aqueous solution, p-sulfonated calix[4]arene could be oxidized when the potential is more than 0.7 V versus SCE. It was confirmed that the reaction was an irreversible two-electron transferred electrochemical reaction. The anodic peak potential, Ep, is affected by the acidity of the solution. The electron transfer coefficient, a, is 0.65. At 25 ℃, the diffusion coefficient of p-sulfonated calix[4]arene is 3.1 ×10-5 cm2.s-1. The activation energy, Ea, for the electrochemical reaction is (18.8±0.2) kJ .mol-1.p-sulfonated calix[4]arene can complex with neutral red and methylene blue in buffer solution. The ratio of the host and the guest in both inclusion complexes was 1:1. The UV-vis spectrum and the Fluorescence spectrum were used to measure the dissociation constants of the inclusion complexes.In aqueous solution, neutral red showed well electrochemical behavior. On gold electrode a pair of redox wave was observed when the potential scaned from -0.3 to -0.8V(vs SCE). The process of the electrode reaction was a quasireversible two-electron transfere electrochemical reaction. At 25℃, the diffusion coefficient of neutral red is 1.35×10-5 cm2.s-1. The activation energy, Ea, for the electrochemical reaction is 20.3 kJ.mol-1.Finally, it was found that when p-sulfonated calix[4]arene was added into the neutral red solution, both anodic and cathodic currents decreased, and the peak potential shifted. Which was also confirmed the formation of the inclusion complex between neutral red and p-sulfonated calix[4]arene.The electrochemical properties of tetrachlorobenzoquinone was also studied. In aqueous solution, tetrachlorobenzoquinone could be reduced on the glassy carbon electrode. The cathodic peak potential, Ep, was affected by the acidity of the solution. Ep shifted in positive direction when pH decreased. That was to say with the increasing of acidity of the solution, the reduction of TCBQ became easier. Otherwise the experimental results showed that the electrode reaction of TCBQ was controlled by an reversible adsorption process.