Gallium(III) and Indium(III) Complexes with <i>meso</i>-Monophosphorylated Porphyrins: Synthesis and Structure. A First Example of Dimers Formed by the Self-Assembly of <i>meso</i>-Porphyrinylphosphonic Acid Monoester

The synthesis and structural characterization, both in solution by means of <sup>1</sup>H and <sup>31</sup>P NMR and UV–vis spectroscopies and in the solid state by X-ray diffraction on single crystal, of a series of gallium­(III) and indium­(III) <i>meso</i>-mono­(diethoxyphosphoryl)­porphyrins bearing different peripheral substituents as well as the corresponding monoesters and phosphonic acids are reported. This work describes the first example of the X-ray structure of a self-assembled dimer formed via strong binding between the oxygen atom of the phosphonate substituent and the gallium­(III) cations of adjacent porphyrin molecules [Ga–O = 1.9708(13) Å].