title: pH-controllable supramolecular systems.
abstract: This Focus Review surveys representative examples of pH-controllable supramolecular systems with interesting features and state-of-the-art applications such as 1) conformational changes within individual molecules; 2) folding/unfolding of polymers; 3) simultaneous binding of cations and anions; 4) logic function; 5) ON-OFF switchable colorimetric sensing; 6) translocation of macrocycle-in-rotaxane molecules; 7) large-scale movement within molecules; and 8) regulation of the substrate flow in nanocontainers. In particular, systems will be discussed that involve: pH-induced conformational changes of a resorcinarene cavitand and a bis(iron porphyrin) complex; pH control in assembly and disassembly of supramolecular systems stabilized with different major noncovalent interactions; pH-driven movements of interlocked molecules involving rotaxanes, molecular elevators, and molecular muscles; and, finally, multicomponent supramolecular systems immobilized on solid supports as pH-responsive nanovalves for the controlled release of specific substrates. Recent advances in the understanding of pH-controllable supramolecular systems have led to the construction of meaningful molecular machines for electronic and biological applications that are amenable to control by simple perturbation with acids and bases.
authors.affiliation: Center of Novel Functional Molecules, Department of Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China. cfleung@cuhk.edu.hk
authors.forename: Ken Cham-Fai
authors.initials: KC
authors.lastname: Leung
authors.forename: Chun-Pong
authors.initials: CP
authors.lastname: Chak
authors.forename: Chui-Man
authors.initials: CM
authors.lastname: Lo
authors.forename: Wing-Yan
authors.initials: WY
authors.lastname: Wong
authors.forename: Shouhu
authors.initials: S
authors.lastname: Xuan
authors.forename: Christopher H K
authors.initials: CH
authors.lastname: Cheng
mesh_terms: D003124:Colorimetry; D003198:Computer Simulation; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D046911:Macromolecular Substances / Q000737:chemistry*; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry; D043862:Rotaxanes / Q000737:chemistry
chemical_list: D046911:Macromolecular Substances; D011108:Polymers; D043862:Rotaxanes