Crystallization of tin(IV) porphyrin controlled by aggregation mode of porphyrins

This paper describes the synthesis of discrete free-standing porphyrin nanoparticles using a reprecipitation method, which is an approach widely used in the synthesis of organic nanoparticles. The crystallization of tin(IV) porphyrin is investigated thoroughly by changing the concentration of aqueous solution for the first time. The morphology is then probed using transmission electron microscopy and atomic force microscopy. It is found that the morphology of the porphyrin nanoparticles changed dramatically in this process. The initial characterization of the porphyrin nanoparticles is analyzed using dynamic light scattering. Further analyses of their aggregation modes are conducted by spectroscopic methods such as ultraviolet–visible (UV–vis) absorption, fluorescence spectra and X-ray diffraction (XRD). Their UV–vis spectra characteristics are discussed in detail. On the basis of the findings, the influence of these peripheral substituents on the sol formation and the aggregation mode is discussed.