Design and preparation of supramolecular polymers is a topic at the forefront of contemporary chemistry, due to its potential fallout in scientific discoveries and technological applications. The essential feature of this class of polymers is the reversibility of the interactions holding together the constituent monomers.
Such reversibility confers two important properties to supramolecular polymers: (i) responsiveness to external stimuli; (ii) self-healing properties. Both features are highly in demand in materials science. We devised and tested a bimodal self-assembly protocol for the generation of a dual-coded supramolecular polymer. Combination of two orthogonal and reversible interactions, namely solvophobic aggregation and metal-coordination, allows precise control at each step of the self-assembly cycle, leading to the formation of rod-like supramolecular architectures.
Following a different approach, we prepared a new class of supramolecular polymers whose self-assembly is driven by the outstanding complexing properties of tetraphosphonate cavitands toward methylpyridinium guests. Cavitand monomers presenting the host functionality at the upper rim and the guest unit at the lower rim self-assemble in solution to give the corresponding homopolymer (see crystal structure below). The remarkable supramolecular plasticity of this system has been proven by the competitive guest triggered reversibility and template driven conversion from linear to star branched polymer (see image below).
The same host-guest association mode was employed for the formation of copolymers, featuring the interesting temperature driven cyclic to linear polymer interconversion.
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R. M. Yebeutchou, F. Tancini, N. Demitri, S. Geremia, R. Mendichi, E. Dalcanale, Angew. Chem. Int. Ed. Engl. 2008, 47, 4504-4508. (Featured as frontispiece).
F. Tancini, R. M. Yebeutchou, L. Pirondini, R. De Zorzi, S. Geremia, O. A. Sherman, E. Dalcanale, Chem. Eur. J. 2010, 16, 14313-14321 (Inside Cover picture).
F. Tancini, E. Rampazzo, E. Dalcanale, Austr. J. Chem. 2010, 63, 646-652.
F. Tancini, E. Dalcanale, Polymerization with Ditopic Cavitand Monomers, Supramolecular Polymer Chemistry (Ed. A. Harada), Wiley-VCH Verlag Gmbh & Co. KGaA, Weinheim, Germany, 2012, 71-93.