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Photo‐Induced Assembly of a Luminescent Tetraruthenium Square
Author(s) -
LaraméeMilette Baptiste,
Nastasi Francesco,
Puntoriero Fausto,
Campagna Sebastiano,
Hanan Garry S.
Publication year - 2017
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.201702714
Subject(s) - supramolecular chemistry , luminescence , self assembly , supramolecular assembly , spectroscopy , quantum yield , excited state , crystallography , materials science , chemistry , chemical physics , crystal structure , nanotechnology , photochemistry , optoelectronics , fluorescence , atomic physics , optics , physics , quantum mechanics
Self‐assembly is a powerful synthetic tool that has led to the development of one‐, two‐ and three‐dimensional architectures. From MOFs to molecular flasks, self‐assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de‐construction of a supramolecular structure through unprecedented photo‐induced assembly and dis‐assembly. The combination of two approaches, a [ n ×1]‐directional bonding strategy and a ligand photo‐dissociation strategy, allows the photo‐induced assembly of a polypyridyl Ru II precursor into a discrete molecular square. Diffusion‐ordered NMR spectroscopy confirmed the synthesis of a higher volume species, while the identity of the species was established by high‐resolution mass spectrometry and single‐crystal X‐ray diffraction studies. The self‐assembled square is not obtained by classical thermal techniques in similar conditions, but is obtained only by light‐irradiation. The tetraruthenium square has an excited‐state lifetime (135 ns), 40 times that of its mononuclear precursor and its luminescence quantum yield (1.0 %) is three orders of magnitude higher. These remarkable luminescence properties are closely related to the relatively rigid square structure of the tetraruthenium assembly, as suggested by slow radiationless decay and transient absorption spectroscopy. The results described herein are a rare example of photo‐induced assembly and dis‐assembly processes, and can open the way to a new avenue in supramolecular chemistry, leading to the preparation of structurally organized supermolecules by photochemical techniques.