ИСТИНА

Coordination polymers composed of porphyrins and metal ions provide a useful platform for supramolecular synthesis of nanostructured materials. А new strategy for self-assembly of porphyrin-based 2D coordination networks in Langmuir monolayers is reported. Unlike common approach, our method uses metal-free ligand as a primary building unit instead of metal complex of tetrapyridyl porphyrin. The interactions of metal ions both with peripheral groups and with a central cavity make it possible to achieve periodically ordered structure of 2D multiporphyrin arrays with face-on orientation of macrocycles. We found that the metalation-demetalation reactions of porphyrin rings control the formation of 2D multiporphyrin arrays and their further transformation into SURMOFs. The incorporation of zinc ions into the porphyrin rings in Langmuir monolayer requires a considerably longer time and higher concentration of salt, when compared to the reaction in solution. The effect of zinc ions on the optical properties of the resulting structure is scale-dependent. Zinc ions boost the fluorescence of TPyP in organic solvent, whereas they induce fluorescence quenching in the monolayer at the air/water interface. Oxygen, which is naturally present in the solvent as well as in the subphase under standard experimental conditions, also assists the decrease of photoluminescence. The networked films deposited from Zn2+-containing subphase onto solid supports possess uniformly smooth morphology demonstrated by SEM and AFM methods.