Synthesis, Characterization And Properties Of Macromolecule Metal Complex Containing Diamine Unit In Main Chain

In passed decades, a great deal of effort has been devoted to theπ- conjugated copolymer bonding with metal ion, i.e. macromolecule metal complex. Films can be cast directly from solutions of the metal-containing polymers, thereby facilitating the fabrication. And combined with the various properties of luminescence, magnetics and catalysis, this kind of materials are interesting for extensive potential applications.Theoretically, the energy transfer efficiency of the macromolecule complex containing metal ion in the backbone should be more effective, but the luminescence properties of such macromolecule complex were not good enough. Through the study on the metal ion detect in polymer solution, we found that Zn2+ was the unique metal ion which can give a new emission rather than quench the emission of copolymer like most transition metal ion, which provide a potential material for improving the luminescence properties of macromolecule complex containing metal ion in the backbone. And the rare earth metal may be another choice because of the unique 4f electron structure could not be affected from the surrounding environment. Based on above analysis, we perform the work hereinafter.We have synthesized series of fluorene-bipyridinyl copolymers by Suzuki reaction, and then the poly-(fluorene-bipyridinyl)-Zn2+ macromolecule complex. The UV and PL spectra study of the solution showed that the introduction of bipyridine could hardly change the optical properties of the polymer. While after forming a polymer-Zn2+ complex, the spectra of the system changed remarkably. Both the UV and fluorescence spectra presented a red-shift, and a novel emitting peak at 500nm occurred in the fluorescence spectra, indicating enhanced fluorescence efficiency in solid film. Investigation of the electrochemistry properties of the series of copolymer and Zn2+ chelating macromolecule complex using cyclic voltammetry exhibited that HOMO and LUMO energy levels of this copolymer are dropped with the increasing BPY content in the copolymer backbone. The energy level of LUMO is decreased from 2.05 eV (polyfluorene) to 2.43 eV. The HOMO and LUMO energy levels of the system obviously dropped after forming polymer- Zn2+ complex. The energy level of LUMO dropped to 2.92 eV, and a decreasing band gap was observed.Quantum chemistry calculation of the synthesized series of fluorene- bipyridinyl copolymers was performed. The calculated LUMO and HOMO energy levels of copolymer P(F-BPY) decrease about 0.40 and 0.51 eV relative to those of Polyfluorene and the downtrend of HOMO and LUMO energy levels is in good accordance with electrochemistry experimental data. As a result of Zn2+ chelation, the global MO energy levels obviously drop, and the more Zn2+ is chelated to copolymer, the larger degree drop the LUMO occurs. The addition of the Zn2+ inducing a lowering of the energy level is due to the electron-withdrawing effect of the positive charge brought about by the Zn2+ chelation to the biprydine. And the new emission after Zn2+ introduced into mainchain is not from the MLCT similar with other metal ion. And this Zn based-copolymer provides a good choice with no-MLCT to improve the properties of the macromolecule complex containing metal in backbone. And the drop of LUMO energy level by the introduction of the Zn2+ make it be potential electron injection materials for the sake of its adjustable LUMO energy level in organic electronic devices.We have successfully synthesized alternating fluorene-phen copolymer P1 and its corresponding Eu (III)–containing copolymer P2, P3 and P4 through Suzuki reaction. Three synthesis strategies of macromolecule rare earth metal complex were designed, namely metalation -after-polymerization, polymerization -after- metalation, and simulating the conditions of small molecules. Though detailed analysis and comparison of the experimental results, we found that designed structured macromolecule rare earth metal complex can be synthesized by polymerization followed by conjugation process using toluene as reaction solvent and dropwise into hexane. In virtue of characters of the NMR spectra of small molecule, we studied the 1H-NMR and IR spectra of the series of Eu-containing copolymer. The Eu (III) has been proved to be undoubtedly introduced into the main chain of the polymer, and the amount of rare earth units in the macromolecule complexes was ascertained to be in accord with the designed feed ratio approximately. The calculated amount of dissociated Eu (III) remained in the system was close to that of Eu(DBM)3.phen or even much less. Thus, the following characterization was for the Eu-containing copolymer eliminating the effect of dissociative Eu (DBM)3 to the system.The PL spectra suggested that the series of macromolecule complex presented the emission originate from the transitions between the 4f states of the Eu (III), a red emission with well monochromatic photoluminescence at 612nm both in solution and in the solid film. And the PL efficiency of P4 is stronger than the blending of Eu(DBM)3 with P1. The emission peak of the copolymer diminished or even quenched in the presence of THF. This revealed that solvent such as ether and alcohol had a decomposition effect to copolymer complex. We investigated the morphology of macromolecule rare earth metal copolymer and the corresponding content of blending the Eu(DBM)3 into copolymer. And we can found that the obvious phase separation in blending system, while the Eu containing copolymer formed by chemical bonding gave a much better homogeneous film. It indicated that the phase separation and ionic aggregation has been efficiently prevented through bonding the Eu into backbone of copolymer. Through forming the Gd complex, we can analyzed the lowest triplet energy level of small molecular ligand phen and polymer ligand P1 respectively, we found the T1 of P1 droped 0.49 eV compare to the T1 of phen, and the gap between the T1 of P1 and the 5D0 energy level of Eu is only 0.12 eV, which make the of energy transfer efficiency from the T1 to 5D0 decrease. This was the reason of the relatively lower solid PL efficiency with small molecular complex. This part work provides a solid base for design, synthesis of new type macromolecule rare earth complex.