Single Polymer Photosensitizer for Tb3+ and Eu3+ Ions: An Approach for White Light Emission Based on Carboxylic-Functionalized Poly(m-phenylenevinylene)s

Abstract

Here, we have demonstrated a facile molecular approach to generate white light emission by combining carboxylic functionalized poly(m-phenylenevinylene)s polymeric architectures with lanthanide ?-diketonate complexes. The new class of carboxylic functional conjugated polymeric materials was custom-designed from phenyl propanoic and acetic acids and structurally characterized by NMR, FT-IR, and MALDI-TOF spectroscopic techniques. The designed conjugated polymers were employed for the synthesis of lanthanide complexes in the presence of acetyl acetone (acac) as coligand and investigated their photophysical properties. For comparison, carboxylic-anchored oligo-phenylenevinylene (OPV) was also designed, characterized, and utilized for the synthesis of lanthanide complexes in the presence of acetyl acetone as coligand. Investigations revealed that carboxylic functionalized polymeric material with Eu3+-?-diketonate complex exhibits unique magenta emission when excited at 310 nm. On the other hand, carboxylic functionalized polymeric material with Tb3+-?-diketonate complex shows bright sky-blue emission. Interestingly, when Eu3+ and Tb3+ were incorporated into polymer backbone in equimolar ratio along with acetyl acetone as coligand, exhibited a white emission with CIE 1976 color coordinates x = 0.28, y = 0.34. The intrinsic quantum yield and lifetime of Ln3+ complexes have been evaluated. The singlet and triplet energy levels of the antenna chromophore ligands have been calculated and the probable energy transfer mechanisms in Ln3+ complexes have also been discussed. The effect of polymer structure and spacer effect on the photosensitizing of Tb3+ and Eu3+ ions was also investigated.