Self-Assembly of Magnesium and Zinc Trimethoxyphenylporphyrin Polymer as Nanospheres and Nanorods

The crystal structures of [Mg(TMPP)] (1) and [Zn(TMPP)] (2) (TMPP = 3,4,5-trimethoxyphenylporphyrin) show that 1 and 2 possess unusual one-dimensional (ID) coordination polymer structure through metal oxygen (oxygen atom from m-methoxy group of adjacent porphyrin) bonds. In 1 and 2, the metal ion is hexa-coordinated with the two axially ligated methoxy groups (bonded through oxygen) from the two neighboring porphyrins. In the nano domain, the self-organization of 1 in dichloromethane (DCM)-petroleum ether is in a spherical shape. Complex 2 self-organizes as a nanorod in DCM-petroleum ether medium. In DCM or in chloroform, such a self-organization process, which is influenced by air bubble formation, transforms the rod to a circular ring. In coordinating solvent like ethanol, the polymer aggregation is terminated in both 1 and 2 to produce relatively large rectangles. The varied ways of self-organization in the nanodomain of these two porphyrins have been discussed.