A nanocomposite gel based on 1D coordination polymers and nanoclusters reversibly gelate water upon heating

A stable nanocomposite metallogel was obtained by the addition of [Na(L)(H2O)]center dot 2H(2)O (HL = 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol) to an aqueous solution of Cu-2(OAc)(4)center dot 2H(2)O in a molar ratio of Cu/L = 4 (5.6 wt% gelator concentration), from which 1D coordination polymers [Cu2L(mu-OAc)(2)(mu-OH)] (1) and coordination nanoclusters {[Cu9L4(OAc)(7)(OH)(5)](2+)}(2) (3) were afforded. The nanoclusters 3 stabilize the 1D coordination polymers 1 and inhibit crystallization of 1 from the system, generating a coordination-based heat-set nanocomposite hydrogel at room and higher temperatures that flows upon cooling to 4 degrees C, in sharp contrast to most supramolecular gels. Reversible thermo and pH responsive solution-gel phase transitions were observed. The results described herein may open a novel avenue for functional coordination nanocomposite materials.