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

What is it about?

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.

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Why is it important?

So far, the hydrogen-bonding interaction and van der Waals interaction have been brought up as major driving forces for sol formation. It should be emphasized, from the present study, that in addition to these interactions, the p–p or halogen–p interaction also plays an important role in the sol formation process by affecting the molecular assembling mode which leads to the final morphology. It is believed that the creation of novel porphyrin aggregation modes can be realized by combining these interactions, which would lead to new functional properties arising from unique porphyrin-based superstructures.

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