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Multi‐Stimuli‐Responsive Organometallic Gels Based on Ferrocene‐Linked Poly(Aryl Ether) Dendrons: Reversible Redox Switching and Pb 2+ ‐Ion Sensing
Author(s) -
Lakshmi Neelakandan Vidhya,
Mandal Dipendu,
Ghosh Sundargopal,
Prasad Edamana
Publication year - 2014
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.201400241
Subject(s) - ferrocene , moiety , dendrimer , chemistry , aryl , ether , polymer chemistry , metal ions in aqueous solution , solvent , redox , selectivity , ligand (biochemistry) , photochemistry , electrochemistry , metal , combinatorial chemistry , inorganic chemistry , organic chemistry , catalysis , biochemistry , alkyl , receptor , electrode
We describe the design, synthesis, and “stimuli‐responsive” study of ferrocene‐linked Fréchet‐type [poly(aryl ether)]‐dendron‐based organometallic gels, in which the ferrocene moiety is attached to the dendron framework through an acyl hydrazone linkage. The low‐molecular‐weight gelators (LMWGs) form robust gels in both polar and non‐polar solvent/solvent mixtures. The organometallic gels undergo stimuli‐responsive behavior through 1) thermal, 2) chemical, and 3) electrochemical methods. Among them, conditions 1 and 3 lead to seamlessly reversible with repeated cycles of identical efficiency. Results indicate that the flexible nature of the poly(aryl ether) dendron framework plays a key role in retaining the reversible electrochemical behavior of ferrocene moiety in the LMWGs. Further, the organometallic gelators have exhibited unique selectivity towards Pb 2+ ions (detection limit ≈10 −8 M ). The metal ion‐sensing results in a gel–sol phase transition associated with a color change visible to the naked eye. Most importantly, decomplexing the metal ion from the system leads to the regeneration of the initial gel morphology, indicating the restoring ability of the organometallic gel. The metal–ligand binding nature has been analyzed by using 1 H NMR spectroscopy, mass spectrometry, and DFT calculations.