Preparation And Photoelectric Properties Of Polyoxometalates/Naphthalene And Porphyrin Hybrid Materials

Recently, organic-polyoxometalate hybrid materials have been attracted growing interests because of their unique structural and photoelectric properties. In the thesis, using Dawson type polyoxometalate as inorganic component, using ethynyl naphthalene, phenyl ethynyl napthalene, naphthyl ethynyl naphthalene and naphthyl ethynyl porphyrin as organic component, the covalent-linked naphthalene-polyoxometalate hybrid materials based on the P-O bonds were synthesized. A series of hybrid Langmuir-Blodgett (LB) films were prepared by LB technique. The structure and photoelectric properties of the hybrids were characterized by NMR, IR, UV-vis absorption spectra, fluorescence spectroscopy, cyclic voltammetry, surface pressure-area isotherms, atomic force microscopy and surface photovoltage spectroscopy.Chapter I IntroductionThe development and preparation of organic-polyoxometalate hybrid materials are introduced briefly. An overview on the polyoxometalate chemistry, structure and preparation of polyoxometalates, selecting of organic ligands and LB technique are made. The reactions utilized in the post-functionalization of the hybrids are introduced as well. Finally, the design ideas and the research purposes are proposed.Chapter II Preparation and characterization of covalently linked ethynyl naphthalene/Dawson type polyoxometalate hybrid materialUnder the condition of pH=2-3, using lacunary Dawson polyoxometalate K10[a-P2W17061](D) as inorganic component,4-ethynyl naphthyl as organic component (N), a covalent-linked ethynyl naphthalene-polyoxometalate (ND) hybrid material based on the P-O bonds was synthesised. Separation and purification methods were discussed. The structure and photoelectric property of the hybird was characterized. A new hybrid LB film was prepared. The two composites can form a conjugated Donor-π-Acceptor system. The photoluminescence spectra indicated that D quenched partial fluorescence of organic ligand possibly due to accepting excited electrons from organic ligand as a good electron acceptor. Hybrid compound ND is easier to accept electrons than D. The hybrid film displayed good conductivity, giving rise to a tunneling current up to±100nA when the voltage was monitored at-1.3～2.7V.Chapter III Covalently linked phenyl ethynyl napthalene, naphthyl ethynyl naphthalene and naphthyl ethynyl porphyrin/Dawson type polyoxometalate hybrid materails:synthesis, and characterizationUsing lacunary Dawson type polyoxometalate as inorganic composite,4-ethynyl phenyl phosphonic acid (O) as organic composite, a covalently linked hybrid (OD) was synthesized. The hybrid (OD) reacted with1-iodonaphthalene, a new organic-inorganic covalently linked compound (N1OD) was synthesized by Sonogashira coupling reaction.The hybrid (ND) reacted with1-iodonaphthalene or Zn(II)-5-(4-iodophenyl)-10,15,20-triphenylporphyrin, respectively, two new organic-inorganic covalently linked compounds (N1ND and PND) were synthesized by Sonogashira coupling reaction. The photoluminescence spectra showed that the polyoxometalate as a good electron acceptor quenched partial fluorescence compared with N1OD, N1ND and PND. The hybrid LB films of N1OD, N,ND and PND were prepared. The results showed that the N1OD, N1ND and PND could form stable LB film. Three LB films showed good conductivity and surface photovoltaic effect. By comparing the three different kinds of LB films, we can see that when the conjugated chain of the hybrid increased, the LB film showed better conductivity and photovoltage response.