Synthesis, characterization, thermal properties and conductivity of oligo-4-[(2-methoxyphenylimino)methyl] phenol

The oxidative polycondensation reaction conditions of 4-[(2- methoxyphenylimino) methyl]phenol (2-MPIMP) were studied by using oxidants such as air and NaOCI in an aqueous alkaline medium between 50°C and 90°C. The structures of synthesized monomer and oligomer were confirmed by FTIR, UV-vis, 1H NMR, 13C NMR and elemental analysis. The characterization was afforded by TGA-DTA, size exclusion chromatography (SEC) and solubility tests. At optimum reaction conditions, the yield of oligo-4-[(2-methoxyphenylimino)methyl]phenol (O-2-MPIMP) was found to be 38.72% and 72.21% by air and NaOCl oxidants, respectively. According to the SEC analysis, the number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) values of O-2-MPIMP were respectively found to be 1400, 2350 g·mol-1, and 1.679 using air and 1650, 2350 g·mol-1, and 1.424 using NaOCl. TGA-DTA analyses of 0-2-MPIMP were shown to be a stable compound against thermal decomposition. The weight losses of 2-MPIMP and 0-2-MPIMP were found to be 57.09% and 59.11% at 1000°C, respectively. Also, electrical conductivity of the O-2-MPIMP was measured, showing that the oligomer was a semiconductor. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of monomer and oligomer were determined from the onset potentials for n-doping and p-doping, respectively. Optical band gaps (E g) of 2-MPIMP and O-2-MPIMP were calculated from UV-vis measurements.