Selective self-assembly of discrete 2D and 3D porphyrinoid architectures using a directional-bonding approach

Herein, we report the coordination-driven self-assembly of a diazaporphyrin plate and a porphyrin prism, made using the same Ru-benzo molecular clip and 2:1 diruthenium acceptor to tetrapyridyl donor stoichiometry, and discuss characterization techniques used to distinguish the two. We describe how ¹H NMR data can distinguish between plate and prism geometries based on peak shifts and splitting in the context of molecular symmetries. DOSY spectra show changes in hydrodynamic radius from the monomeric porphyrin to the prism (4.78 Å to 15.2 Å) and diazaporphyrin to plate (6.02 Å to 12.2 Å) consistent with the increase in size upon assembly. High resolution mass spectrometry provides further evidence for plate and prism, where specific peaks at diagnostic m/z values unequivocally establish the stoichiometry of assembly. Electronic absorption spectroscopy revealed a marked increase in molar absorptivity upon self-assembly. These results establish how molecular characterization techniques may be used to distinguish between possible self-assembly outcomes when a given building block may be encoded with directionality that is suitable for more than one geometry.