Dataset Information

Ion pair-induced conformational motion in calix[4]arene-strapped calix[4]pyrroles.

ABSTRACT: In order to understand the still-poorly understood interplay between calix[4]arene conformations and cation and anion recognition in multicomponent systems, the ion pair receptors 1 and 2 were synthesized. In solution and in the solid state, the calix[4]arene subunit of receptor 1 adopts a cone conformation, while that of 2 interconverts between the cone and the partial cone conformation. These geometric features differ from previous systems where the calix[4]arene moiety was locked in the 1,3-alternate conformation. A combination of 1H NMR spectroscopic analyses and single crystal X-ray diffraction studies reveal that receptor 1 binds the fluoride and the chloride anion via significantly different binding modes, displaying, for instance, 1 : 1 and 2 : 3 binding stoichiometries with CsF and CsCl, respectively. In the case of 2, the conformation of the calix[4]arene constituent of 2 is highly dependent on the size and quantity of anions present. For example, upon treatment of 2 with the fluoride anion (as both the TBA+ and Cs+ salts), the calix[4]arene unit coexists as cone and partial cone conformers that are inter-convertible. In the presence of excess CsF, the aromatic rings of the calix[4]arene subunit becomes locked in the pinched cone conformation with the result that an ion pair-mediated coordination polymer is formed. In the presence of excess CsCl, the calix[4]arene unit of 2 adopts only the partial cone conformation stabilized by aryl CH-anion hydrogen bonding interactions. The present systems constitute a rare set of related receptors wherein the effects of conformational changes are so tightly coupled with ion recognition.

SUBMITTER: Kim SK

PROVIDER: S-EPMC5811093 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:The importance of noncovalent interactions in the realm of biological materials continues to inspire efforts to create artificial supramolecular polymeric architectures. These types of self-assembled materials hold great promise as environmentally stimuli-responsive materials because they are capable of adjusting their various structural parameters, such as chain length, architecture, conformation, and dynamics, to new surrounding environments upon exposure to appropriate external stimuli. Nevertheless, in spite of considerable advances in the area of responsive materials, it has proved challenging to create synthetic self-assembled materials that respond to highly disparate analytes and whose environmentally induced changes in structure can be followed directly through both various spectroscopic and X-ray diffraction analyses. Herein, we report a new set of artificial self-assembled materials obtained by simply mixing two appropriately chosen, heterocomplementary macrocyclic receptors, namely a tetrathiafulvalene-functionalized calix[4]pyrrole and a bis(dinitrophenyl)-meso-substituted calix[4]pyrrole. The resulting polymeric materials, stabilized by combination of donor-acceptor and hydrogen bonding interactions, undergo dynamic, reversible dual guest-dependent structural transformations upon exposure to two very different types of external chemical inputs, namely chloride anion and trinitrobenzene. The structure and dynamics of the copolymers and their analyte-dependent responsive behavior was established via single crystal X-ray crystallography, SEM, heterocomplementary isodesmic analysis, 1- and 2D NMR, and dynamic light scattering spectroscopies. Our results demonstrate the benefit of using designed heterocomplementary interactions of two functional macrocyclic receptors to create synthetic, self-assembled materials for the development of "smart" sensory materials that mimic the key biological attributes of multianalyte recognition and substrate-dependent multisignaling.

Dataset Information

Ion pair-induced conformational motion in calix[4]arene-strapped calix[4]pyrroles.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure