Synthesis of soluble poly(azomethine)s containing thiophene and their fluorescence quantum yields

In this study, poly(azomethine)s containing thiophene unit and with pyridine, oxygen and sulfur bridges are synthesized via the condensation reaction at the organic medium. The obtained compounds were structurally clarified by Fourier-transform infrared, ultraviolet-visible and nuclear magnetic resonance (¹H, ¹³C NMR) spectroscopic techniques. Replies of optic and electronic excitation were getting and utilized by photoluminescence (PL) spectroscopy and cyclic voltammetry techniques. In addition, thermal characteristics were obtained by thermogravimetric/differential thermal analyses and differential scanning calorimetry analysis. Photochromic properties and quantum yields were particularly examined by PL spectroscopy. In particular, P-ThPy compound has multicolor emissions and high quantum yields in DMF and EtOH solvents. It has five colors such as blue (excited at 340, 360, 380, 400, 420, 440 nm), green (460 nm), yellow (480 nm), orange (500 nm) and red (520 nm) emissions in DMF solvent. Additionally, it determined two different colors, blue (320, 340, 360, 380, 400, 420, 440, 460 nm) and yellow (480 nm) emissions in EtOH solvent. The quantum yields of P-ThPy were found as 19.6% and 22.1% and 9.0%, 11.0% in DMF and EtOH solvents, respectively, when excited at 460, 480 nm for DMF and at 420, 460 nm for EtOH.