Synthesis And Properties Of Metallo-supramolecular Polymers Containing Electron Donor And Acceptor

Supramolecular compounds based on non-covalent bonds have been received considerableattentions in recent years. Especially, terpyridine (tpy) with a strong binding ability with a varietyof transition metal ions have been widely used in supramolecular polymers with a linear structure.Furthermore, the introduction of electron donor and acceptor (D-A) structure in molecule lead toobvious change of band gap, and then the spectral properties and improve the balance of theinjecting and transporting of electron or/and hole. In this thesis, the different D-A structures wereintroduced into mainchain of supramolecular polymers. A series of monomers with different D-Astrength was designed and synthesized and some photoelectric functional materials with tunablecolors and efficient emission were obtained. At the same time, the relationship between structuresand properties was studied systematically.(1) The study of supramolecular copolymers that formed by monomers with differentelectronic structure. Compounds CNPVTPY,36CzTPY and FTPY with different electronicstructure, which is tpy-D-tpy and tpy-A-tpy, were synthesized based on terpyridine modified withcyano-p-phenylenevinylene (CNPV), carbazole and fluorine moieties. Via self-assemblypolymerization directed by transition metal ions Zn2+, the metallo-homopolymers PFTPY,P36CzTPY, PCNPVTPY and metallo-copolymers CoPFCNPVTPY, CoP36CzCNPVTPY wereobtained. The structures of these compounds were characterized fully by1H-NMR,13C-NMR andMS and a detail study on UV-visible absorption properties, fluorescence emission properties,electrochemical and thermal properties of the monomers and metal-supramolecular polymers wereinvestigated. The results showed that, with respect to the monomer, the UV-visible absorption andfluorescence emission peaks of the polymer containing D-A structure were redshift significantly.This was due to the introduction of metal ions enhanced the electron-withdrawing ability of theelectron acceptor, which promoted intermolecule charge transfer (ICT). Relative to the monomers, the UV-visible absorption peaks of polymers PFTPYZn and P36CzTPY redshift of42nm and58nm in CHCl3, respectively. While absorption peak of PCNPVTPYZn only redshifted5nmresulting from lack of D-A structure. Compared with monomers, the emission peaks of thesepolymers redshifted110nm,172nm and107nm in toluene, respectively.(2)The study of D-A-based molecules that formed by terpyridine and different intensity ofelectron donors, as well as the study of their supramolecular polymers. Through introducingelectron donors possessed different electron-donating ability based bithiophene derivative intoterpyridine, monomers containing biterpyridyl moiety27CzTPY, DTSTPY and DTPTPY wereobtained. Directed by transition metal ions, their metallo-supramolecular polymers P27CzTPYZn,PDTSTPYZn and PDTPTPYZn were obtained. Systemic characterization and study of theirstructure and properties were investigated. The study results exhibited that, the properties ofmonomer depended on its D-A intensity strongly. The stronger the intensity of monomer, thelonger the wavelength of the UV-visible absorption peak and the fluorescence emission peakwhich caused by ICT. The UV-visible absorption peak value of DTPTPY with the stongest D-Aintensity was429nm in toluene, redshifted76nm relatived to27CzTPY with the weakest D-Aintensity. The emission peaks of27CzTPY, DTSTPY and DTPTPY were408nm,479nm and487nm respecively. Study also showed that when the electron acceptor was the same, thestronger the electron-donating ability of electron donor, the lower the onset oxidation potentialand the HOMO energy, finally it performed a narrower bandgap. The Eg of27CzTPY, DTSTPYand DTPTPY were2.62eV,2.51eV and2.13eV, respectively. The photophysical properties ofpolymers also performed that the UV-visible absorption peak and fluorescence emission peakcaused by intramolecular charge transfer (ICT) significantly redshifted compared withmonomers.