“…51,58,[60][61][62][63][64][65][66][67][68][69][70] The defining molecular recognition properties of Q[n] hosts include their high affinity and selectivity [62][63][64][65][66][67] toward hydrophobic dications in water, their constrictive binding, their high stimulus responsiveness (e.g., pH, electrochemical, chemical, and photochemical), and the low polarizability of the Q[n] cavity. 29,30,55,[68][69][70][71] Therefore, Q[n]s have been effectively utilized to develop drug-delivery systems, 62,72,73 engage in biomolecular recognition, 74,75 create adsorptive separation materials, [76][77][78][79][80] fabricate supramolecular polymers, [81][82][83][84][85] and to establish chemical sensing ensembles. [86][87][88] Double-cavity Q[n]s are distinguished not only by their novel structures but, more significantly, by their unique properties.…”