A simple, rapid and sensitive method has been developed for determination of traces of silver(I) (0.2 - 13 ng mL(-1)) based on its catalytic effect on the oxidation of thionine by peroxodisulfate in the presence of 1 - 10 phenanthroline as an activator. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 600 nm by the fixed time method. The de...

The fabrication of silk-based membranes that are stable, optically transparent and reusable is yet to be achieved. To address this bottleneck we have developed a method to produce transparent chromogenic silk patches that are optically responsive to pH. The patches were produced by blending regenerated silk fibroin (RSF), Laponite RD (nano clay) and the organic dyes neutral red and Thionine ace...

The monomer-dimer equilibrium and thermodynamic of several ionic dyes (Neutral Red, Nile Blue A, Safranine T and Thionine) has been investigated by means of spectrophotometric and chemometrics methods. The dimerization constants of these ionic dyes have been determined by studying the dependence of their absorption spectra on the temperature in the range 20-75 degrees C at concentrations of Neu...

The mechanism of the fluorescence quenching of aqueous thionine by various metal ions (Ce3+_, Fe2+, Mn2+, Mg2+, Cs+ and Na+) was studied at pn = 2.5. The following Stern-Volmer constants (K s v) were determined: XSv(Fe2+) == 1.13 dm3 mol -1 , Ksw(Mn2+) = 0.24 dm3 mol"1, Ksv(Ce3+) = 0.24 dm3 mol -1, i£sv(Cs~) — 0.03 dm3 mol -1 . At concentrations below 1 mol.dm -3 Na2S04 and MgS04 are very weak ...

A study of the possible intersystem crossing (ISC) mechanisms (S→T) in thionine (3,7-diamino-phenothiazin-5-ium), which is conducive to the efficient population of the triplet manifold, is presented. The radiationless deactivation channels {S(1),S(2)(π → π*) → T(1),T(2)(π → π*)} have been examined. Since the direct ISC does not explain the high triplet quantum yield in this system, attention ha...

a simple, sensitive and rapid method for determination of trace amounts of nitrite ion in real samples is reported. the reaction is initiated by adding known volumes of a nitrite ion solution of identified concentration to acidic solutions of thionine which causes decolorizaiton of reagent with time. the absorbance changes is then monitored spectrophotometrically at lmax = 602nm at 25 °c. calib...