A highly selective Cu2+-coordination triggered multi-stimuli responsive and functional metallogel of bis-terpyridyl-based low molecular weight (LMW) gelator

Abstract

An oligo(ethylene glycol) (OEG) bridged two-armed bis-terpyridyl-based ligand has been synthesized, which can serve as a low molecular weight (LMW) gelator affording a metallogel upon selective coordination to Cu(II) metal ions. The gelator can form a metallogel at a concentration as low as 0.5 wt%. The gel exhibits various remarkable stimuli responsive behaviors with an alternate gel to sol transition, and it responds to a wide range of stimuli, including pH, temperature, and mechanical and chemical stimuli. The obtained soft material has been fully characterized by using a combination of experimental techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and rheology measurements. The metallogel exhibits multifunctional properties, including self-healing behavior, and can tolerate a wide range of physical and chemical changes. The gel in its dried form (xerogel) shows excellent selective adsorption properties towards the anionic dye Congo red. Moreover, the gel can also detect ammonia in the gel state by changing color and state. Most importantly, the fibrous networked metallogel also exhibits excellent catalytic activity for the azide–alkyne cycloaddition (CuAAC) reaction and serves as a recyclable catalyst supported by the air-stable networked xerogel.