title: Multiaddressable molecular rectangles with reversible host-guest interactions: modulation of pH-controlled guest release and capture.
abstract: A series of multiaddressable platinum(II) molecular rectangles with different rigidities and cavity sizes has been synthesized by endcapping the U-shaped diplatinum(II) terpyridine moiety with various bis-alkynyl ligands. The studies of the host-guest association with various square planar platinum(II), palladium(II), and gold(III) complexes and the related low-dimensional gold(I) complexes, most of which are potential anticancer therapeutics, have been performed. Excellent guest confinement and selectivity of the rectangular architecture have been shown. Introduction of pH-responsive functionalities to the ligand backbone generates multifunctional molecular rectangles that exhibit reversible guest release and capture on the addition of acids and bases, indicating their potential in controlled therapeutics delivery on pH modulation. The reversible host-guest interactions are found to be strongly perturbed by metal-metal and π-π interactions and to a certain extent, electrostatic interactions, giving rise to various spectroscopic changes depending on the nature of the guest molecules. Their binding mode and thermodynamic parameters have been determined by 2D NMR and van't Hoff analysis and supported by computational study.
authors.affiliation: Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Alan Kwun-Wa
authors.initials: AK
authors.lastname: Chan
authors.affiliation: Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Wai Han
authors.initials: WH
authors.lastname: Lam
authors.affiliation: Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Tanaka
authors.affiliation: Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Keith Man-Chung
authors.initials: KM
authors.lastname: Wong
authors.affiliation: Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry, The University of Hong Kong, Hong Kong, People's Republic of China wwyam@hku.hk.
authors.forename: Vivian Wing-Wah
authors.initials: VW
authors.lastname: Yam
keywords: luminescence; noncovalent interactions; platinum complex