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Giant Shape‐Persistent Tetrahedral Porphyrin System: Light‐Induced Charge Separation
Author(s) -
Marchini Marianna,
Luisa Alessandra,
Bergamini Giacomo,
Armaroli Nicola,
Ventura Barbara,
Baroncini Massimo,
Demitri Nicola,
Iengo Elisabetta,
Ceroni Paola
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202102135
Subject(s) - ruthenium , porphyrin , photochemistry , supramolecular chemistry , phosphorescence , crystallography , quenching (fluorescence) , chemistry , supramolecular assembly , materials science , crystal structure , fluorescence , biochemistry , physics , quantum mechanics , catalysis
Tetraphenylmethane appended with four pyridylpyridinium units works as a scaffold to self‐assemble four ruthenium porphyrins in a tetrahedral shape‐persistent giant architecture. The resulting supramolecular structure has been characterised in the solid state by X‐ray single crystal analysis and in solution by various techniques. Multinuclear NMR spectroscopy confirms the 1 : 4 stoichiometry with the formation of a highly symmetric structure. The self‐assembly process can be monitored by changes of the redox potentials, as well as by modifications in the visible absorption spectrum of the ruthenium porphyrin and by a complete quenching of both the bright fluorescence of the tetracationic scaffold and the weak phosphorescence of the ruthenium porphyrin. An ultrafast photoinduced electron transfer is responsible for this quenching process. The lifetime of the resulting charge separated state (800 ps) is about four times longer in the giant supramolecular structure compared to the model 1 : 1 complex formed by the ruthenium porphyrin and a single pyridylpyridinium unit. Electron delocalization over the tetrameric pyridinium structure is likely to be responsible for this effect.