Hierarchical aggregation mechanism in heat-set metallosupramolecular gels using a tritopic functional ligand exhibiting temperature-triggered cis-to-trans molecular conversions.

We present the aggregation mechanism in a novel class of heat-set metallosupramol. Ni2BTC gels formed by complexation of a bis-terpyridine-cyclam (BTC), a tritopic ligand, with nickel ions (ii). Viscosimetry, rheol., small-angle X-ray scattering, dynamic light scattering and impedance spectroscopy measurements are used to investigate the aggregative properties. Gels are obtained by heating the homogeneous solns. (Ni2BTC in dimethylformamide) from room temp. to 50 °C for 24 h, which is a remarkable phenomenol. in the class of org. mol. gels. The hierarchical aggregation mechanism relies on a temp.-triggered cis-to-trans mol. conversion of the tritopic ligand at the central cyclam unit. At the nanoscale, the expansion of the coil-like species in the liq. phase to rodcoils allows, beyond a crit. concn., their percolation into transient gel networks. The use of such tritopic ligands gives access to homo- or hetero-metallogels that adapt their properties to the environmental conditions (temp., pH, mech. stress and applied elec. potential). Various mol. adjustment parameters (metal ions, metal sequence, metal-ligand stoichiometry, cyclam substituents) can be used to tune the aggregative properties of the system. [on SciFinder(R)]

Références

Titre
Hierarchical aggregation mechanism in heat-set metallosupramolecular gels using a tritopic functional ligand exhibiting temperature-triggered cis-to-trans molecular conversions.
Type de publication
Article de revue
Année de publication
2013
Revue
Soft Matter
Volume
9
Pagination
4428–4436
ISSN
1744-683X
Soumis le 12 avril 2018