Preparation, characterization and luminescence properties of a novel 1,10-phenanthroline-functionalized polyimide and its europium(III) complexes

A novel 1,10-phenanthroline-functionalized polyimide (CMPI-Phen) was prepared as polymer matrix by the nucleophilic substitution reaction between chloromethylated polyimide (CMPI) and 5-amino-1,10-phenanthroline (NH2-Phen). Then, two kinds of luminescent materials of 1,10-phenanthroline-functionalized polyimide containing Eu(III) complexes, were obtained by two different methods. Their structures and properties were characterized by Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, elemental analysis, inductively coupled plasma (ICP), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), luminescence spectrometry, and luminescence decay analysis. Investigations revealed that both the CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 display highly efficient red emissions, suggesting their potential application as luminescent materials. However, compared with CMPI-Phen-Eu(III), CMPI-Phen-Eu(TTA)3, where TTA stands for thenoyltrifluoroacetone, exhibits more excellent and stable fluorescence intensity and longer luminescence lifetime (134.30 μs). The weight-average molecular weights of CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 are 2.40×104 and 3.11×104, respectively. The Eu contents of CMPI-Phen-Eu(TTA)3 and CMPI-Phen-Eu(III) were measured by ICP to be 7.00% and 5.92%, respectively. TGA demonstrated that both CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 have high thermal stability and their 5% loss weight temperatures were 356 and 280 °C, respectively. Moreover, both CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)3 were soluble in polar solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO) under heating conditions, and could be easily cast into tough thin films. Open image in new window