New microstructured chromium doped poly(p-toluidine) as a new acid-base indicator and precursor for chromic oxide nanostructured

摘要

New chromium doped poly(p-toluidine) (Cr-PPT) was synthesized via chemical oxidative polymerization of p-toluidine with potassium dichromate as an initiator in acidic aqueous medium. The spectrophotometric behavior of Cr-PPT in acetone and chloroform as different solvents was investigated. Cr-PPT exhibits bathochromically red shift at 46-nm value with the increasing of solvent polarity. The intermolecular charge transfer band peak for Cr-PPT shifted from 422nm in low-polar solvent (chloroform) to high-polar solvent (acetone) to 468nm. Optical absorption measurements are used to obtain the energy gap of prepared Cr-PPT. Cr-PPT has an optical band gap (E-g=1.90 to 2.05eV) that is located in the semiconductor range. Pink color was observed using Cr-PPT solution in acidic media while it changes sharply to yellow in basic medium. Based on intermolecular charge transfer, the Cr-PPT was used as acid-base indicator. Cr-PPT and phenolphthalein (phph) indicator were used for determination of normality of HCl using standard 0.1N NaOH, the two indicators gave equal end point values. Using Cr-PPT as a new molecular precursor for the production chromium oxide in nanoscale by thermal decomposition route was studied, and the average size of synthesized Cr2O3 was found in the range of 54-61nm. Copyright (c) 2017 John Wiley & Sons, Ltd.