Bispicolyamine-Based Supramolecular Polymeric Gels Induced by Distinct Different Driving Forces with and Without Zn(2+)

Metal-coordination polymeric gels are interesting areas as organic/inorganic hybrid supramolecular materials. The bispicolylamine (BPA) based gelator (1) showed excellent gelation with typical fibrillar morphology in acetonitrile. Upon complexing 1 with Zn(2+), complexes ([1 + Zn + ACN](2+) and [1 + zinc trifluoromethanesulfonate (ZnOTf)](+)) with four coordination numbers were formed, which determine the gel structure significantly. A gel-sol transition was induced, driven by the ratio of the two metal complexes produced. Through nuclear magnetic resonance analysis, the driving forces in the gel formation (i.e., hydrogen-bonding and π–π stacking) were observed in detail. In the absence and the presence of Zn(2+), the intermolecular hydrogen-bonds and π–π stacking were the primary driving forces in the gel formation, respectively. In addition, the supramolecular gels exhibited a monolayer lamellar structure irrespective of Zn(2+). Conclusively, the gels’ elasticity and viscosity reduced in the presence of Zn(2+).