Coordination Polymer Gels with Modular Nanomorphologies, Tunable Emissions, and Stimuli-Responsive Behavior Based on an Amphiphilic Tripodal Gelator
journal contributionposted on 09.08.2017 by Papri Sutar, Tapas Kumar Maji
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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 (L) 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. L can also act as a selective chemosensor for ZnII with very low limit of detection (0.18 ppm) in aqueous medium. Coordination-driven self-assembly of L with ZnII in H2O/MeOH solvent mixture results in a coordination polymer hydrogel (ZnL) that exhibits sheet like morphology and charge-transfer emission. On the other hand, coordination of L with TbIII and EuIII in CHCl3/tetrahydrofuran solvent mixture results in green- and red-emissive CPGs, respectively, with nanotubular morphology. Moreover, precise stoichiometric control of L/EuIII/TbIII 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 LnIII-tpy coordination.