Coordination Polymer Gels with Modular Nanomorphologies, Tunable Emissions, and Stimuli-Responsive Behavior Based on an Amphiphilic Tripodal Gelator
2017-08-09T14:34:58Z (GMT) by
The recent upsurge in research on coordination polymer gels (CPGs) stems from their synthetic modularity, nanoscale processability, and versatile functionalities. Here we report self-assembly of an amphiphilic, tripodal low-molecular weight gelator (<b>L</b>) that consists of 4,4′,4-[1,3,5-phenyl-tri(methoxy)]-tris-benzene core and 2,2′:6′,2″-terpyridyl termini, with different metal ions toward the formation of CPGs that show controllable nanomorphologies, tunable emission, and stimuli–responsive behaviors. <b>L</b> can also act as a selective chemosensor for Zn<sup>II</sup> with very low limit of detection (0.18 ppm) in aqueous medium. Coordination-driven self-assembly of <b>L</b> with Zn<sup>II</sup> in H<sub>2</sub>O/MeOH solvent mixture results in a coordination polymer hydrogel (<b>ZnL</b>) that exhibits sheet <i>like</i> morphology and charge-transfer emission. On the other hand, coordination of <b>L</b> with Tb<sup>III</sup> and Eu<sup>III</sup> in CHCl<sub>3</sub>/tetrahydrofuran solvent mixture results in green- and red-emissive CPGs, respectively, with nanotubular morphology. Moreover, precise stoichiometric control of <b>L</b>/Eu<sup>III</sup>/Tb<sup>III</sup> ratio leads to the formation of bimetallic CPGs that show emissions over a broad spectral range, including white-light-emission. We also explore the multistimuli responsive properties of the white-light-emitting CPG by exploiting the dynamics of Ln<sup>III</sup>-tpy coordination.