Kazuya Ohga

Electrochemiluminescence oxalic acid sensor having a platinum electrode coated with chitosan modified with a ruthenium (II) complex

Abstract An electrochemiluminescence (ECL) sensor having a Pt electrode coated with a tris(2,2′-bipyridine)ruthenium (II)(Ru(II) complex)-modified chitosan responded to oxalic acid more strongly than to several other substrates. The ECL response intensity to oxalic acid was reproducible within 5% (RSD) on 10 repeated runs. A calibration curve for oxalic acid gave a straight line in the concentration range of 0.1 to 10 mM (correlation coefficient, 0.997) and the detection limit (S/N=3) was estimated to be 3×10 −5 M. Interestingly, the response to trimethylamine was 39 times as weak as that obtained with a bare Pt electrode in an aqueous solution where the Ru(II) complex coexisted. The appearance of the high selectivity can be explained partly on the basis of the electrostatic repulsion of the chitosan membrane having a positive charge with trimethylamine, as being supported by cyclic voltammetry.

Quadruple Decker [3.3][3.3][3.3]Orthocyclophane Acetal—An Orthocyclophane Ladder

Through clever bridging of orthocyclophanes (in this case by acetalization), molecules such as 1 can be formed with four benzene rings in a stacked face-to-face arrangement. UV/Vis spectroscopic and electrochemical properties of 1 are governed by π-π through-space interactions within the molecule.

Fabrication of a Trimethylamine Gas Sensor Based on Electrochemiluminescence of Ru(bpy)

The present sensor on the basis of electrochemiluminescence generated from Ru(bpy)/ anionic perfluoropolymer Nafion coated electrode responded strongly to trimethylamine gas. The response gave a straight line in the concentration ranging from 10 to 310 ppb and the lower detection limit was 3 ppb (S/N =3). The sensor was applied to seafood as practical samples and the response for a squid was almost consistent with a profile curve obtained from the K value measurement as an alternative freshness index.