Synthesis And Characterization Of Functionalized Graphene With Novel Water-Soluble Metal Phthalocyanine

Graphene as a novel carbon material has broad application prospects in manyfields due to its unique electrochemical behavior, high mechanical strength, highelectron transfer rate et al. But its poor dispersion in solvent and compatibility limit itsapplication to some extent. Recently, grapheme oxide (GO) and reduced graphemeoxide (RGO) have attracted more attention because of their good dispersion in solventand modifiability. GO or RGO have been modified with different kinds of functionalgroups and compounds through covalent and non-covalent methods.Phthalocyanines possess excellent optical properties and have been widely used in thefield of solar cell materials, electrochromic photochromic materials, nonlinearmaterials and photovoltaic conversion materials. In this work, novel functionalizedgraphene materials modified with water soluble phthalocyanines which containimidazolium cationic ions were prepared successfully using non-covalent method.Their structures and optical properties were characterized in detail.The main work is as follows:1. Two cationic water-soluble phthalocyanines ImPcZn and ImPcCu weresynthesized through introducing four imidazole cationic substituents. Their solubility,aggregation state in different kinds of solvent and spectroscopic properties werestudied in detail. These two compounds all showed well solubility in methanol, DMFand water. In the two former solvents, monomeric species give the sharp Q-band at675nm and678nm respectively. But in water, the intensity of the Q-band is muchlower than in methanol and DMF, indicating aggregation due to cofacial arrangementof the phthalocyanines. The addition of TX-100in ImPcZn water solvent can reducethe aggregation obviously, but can not for ImPcCu. In addition, ImPcZn gaveemission at693nm, but no emission was found from ImPcCu.2. Three novel functionalized graphene materials modified with water-solublemetal phthalocyanine ImPcZn-GO、ImPcCu-GO�'�ImPcZn-RGO were synthesizedsuccessfully utilizing two kinds of adsorption interactions: π-π interaction andelectrostatic adsorption between phthalocyanine molecules and the surface ofgraphene oxide or reduced graphene oxide. Their structures were characterized byFI-IR, XRD and TEM. Their properties were investigated by UV-vis, fluorescence emission spectra and Zeta potential. The maximum adsorption quantities in compositeImPcZn-GO、ImPcCu-GO and ImPcZn-RGO were determined as0.25mg/1mg，0.24mg/1mg�'�0.34mg/1mg. The adsorption quantity in ImPcZn-RGO is larger thanthat in ImPcZn-GO due to the larger π planar in RGO.3. The redshifted Q-band of phthalocyanines was found after being adsorbed onthe surface of graphene, which can be attributed to the strong π-π interaction betweenphthalocyanine molecules and the surface of graphene oxide. Moreover, the emissionquenching of phthalocyanines after being adsorbed indicate that some energy transferor electron transfer process happened in the composite after being excited.