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, H-1 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 mu s). The weight-average molecular weights of CMPI-Phen-Eu(III) and CMPI-Phen-Eu(TTA)(3) are 2.40x10(4) and 3.11x10(4), 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 A degrees 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.