Synthesis and characterization of silica microspheres functionalized with porphyrin monolayer

A new type of inorganic and organic composite (SiO2-MPS-TAPPI), oppositely charged meso-tetra-(4-trimethylaminophenyl)porphyrin iodide (TAPPI) bonded on the surface of silica microspheres coated with mercaptopropyltrimethoxysilane (MPS), was prepared by self-assembly method. The composite was tested by TEM, XRD and TG. The TEM images show that SiO2-MPS microspheres in the composite are uniform. There are linkages among some different SiO2-MPS microspheres. The XRD measurement bears out that the composite structure is the same with SiO2-MPS. TG curves show that thermal stability of TAPPI assembled onto SiO2-MPS microspheres is higher than that of TAPPI. Solid UV diffusion reflection spectra and fluorescence spectra are used to investigate the photophysical properties of the SiO2-MPS-TAPPI composite. It is showed that the spectra of the composite exhibit significant enhancement of the spectra range. The strong interaction between TAPPI and SiO2-MPS in the composite is responsible for the different spectra.