Coordination Compounds As Templates For The Synthesis Of Organic/inorganic Nanomaterials In Ionic Liquids

It is a versatile way that using coordination compounds both as precursor and template in the preparation and modification of nanomaterials. The novel structure of coordination compounds can give the effect on the growth of nanoparticles, and the ligands can cap surface to stabilize freshly formed nanoparticles. Thus organic-inorganic materials are obtained. However, inorganic coordination compounds usually are hardly dissolving in water andmost organic solvents, except ionic liquids (ILs). ILs are organic salts entirely composed of ions, which have low melting points. They are good solvents for a wide range of inorganic, organic, and polymer materials. Most recently, synthesis of nano- and microstructured inorganic materials in ILs has aroused more and more attention because of its effective soft template effect, reproducibility, and simple maneuverability. According to literatures, we synthesized ZnS, PbS, and Ag nanoparticles modified with ligands from coordination compounds in ILs. The main works are listed as follows:(1) Zn(FCA)₂ (FCA = 3-Ferrocenyl-2-crotonic acid) coordination polymer has been synthesized and characterized. 1-D polymeric chain structure of Zn(FCA)₂ is excellent template for the synthesis of organized assemblies of ZnS nanoparticles by an ionic liquid-assisted templating. In this work, we illustrate the formation mechanism of ZnS nanoparticles with spherical and peanut-like shapes. We explain the change of coordination mode for the carboxylate groups form FCA ligand which is revealed by FT-IR spectra. And we think the carboxylate groups use the bidentate coordination mode modified on the surface of nanoparticles.(2) ZnT(p-Br)PP (T(p-Br)PP = tetra(p-bromophenyl)porphyrin) has been designed and synthesized. The crystal structure of ZnT(p-Br)PP was obtained and discussed. It exhibited nice molecule planarity. ZnT(p-Br)PP organic nanoplates was synthesized and characterized by XRD, TEM and SEM. Using ZnT(p-Br)PP as precursor, nanorod ZnS with different sizes were prepared by two methods and their optical properties were studied (their fluorescence peaks appeared at approximately 350 nm). The formation mechanism of rod-like ZnS nanoparticles was illustrated.(3) PbS nanocube has been successfully synthesized in an ionic liquid, which has soft template effect. HRTEM showed the cubic morphology of PbS, its crystallite morphology and the crystal orientation. Carbazole derivatives (L) and Pb coordination compound have been synthesized and characterized. PbS naocrystalline under 10 nm was obtained by using Pb coordination compound as precursor. The UV-vis spectra of PbS solution at different reaction stages were examined. The photoluminescence of L, PbL₂, and PbS nanoparticles were compared and they were similar. However, due to cooperative effect between L and PbS nanoparticles, the maximum fluorescence peak of PbS nanoparticles blue-shifted about 40 nm, and the FWHM broadened about 20 nm.(4) Ag nanoparticles were synthesized by Ag coordination compound self-reduction method. The products were characterized by UV-vis spectra and cyclic voltammetry. The polarity of solution affects the size and shape of Ag nanoparticles: with increasing of the polarity of solution, the shape of Ag nanoparticles transformed from spherical to rodlike shape and their sizes increased. We also facilely synthesized triangular and hexagonal silver nanoplates in three-cavity-diffusion device at low temperature and ambient atmosphere. XRD showed they are single crystals, with the basal plane as (111) lattice plane.