Sterically Controlled Recognition of Macromolecular Sequence Information by Molecular Tweezers

Abstract

Sequence-specific binding is demonstrated between pyrene-based tweezer molecules and soluble, high molar mass copolyimides. The binding involves complementary pi-pi stacking interactions, polymer chain-folding, and hydrogen bonding and is extremely sensitive to the steric environment around the pyromellitimide binding-site. A detailed picture of the intermolecular interactions involved has been obtained through single-crystal X-ray studies of tweezer complexes with model diimides. Ring-current magnetic shielding of polyimide protons by the pyrene "arms" of the tweezer molecule induces large complexation shifts of the corresponding 1H NMR resonances, enabling specific triplet sequences to be identified by their complexation shifts. Extended comonomer sequences (triplets of triplets in which the monomer residues differ only by the presence or absence of a methyl group) can be "read" by a mechanism which involves multiple binding of tweezer molecules to adjacent diimide residues within the copolymer chain. The adjacent-binding model for sequence recognition has been validated by two conceptually different sets of tweezer binding experiments. One approach compares sequence-recognition events for copolyimides having either restricted or unrestricted triple-triplet sequences, and the other makes use of copolymers containing both strongly binding and completely nonbinding diimide residues. In all cases the nature and relative proportions of triple-triplet sequences predicted by the adjacent-binding model are fully consistent with the observed 1H NMR data.

Perylene as an electron-rich moiety in healable, complementary π–π stacked, supramolecular polymer systems

“…S6eS11 and SI Equation S1). This result was consistent with values previously reported [48] by Burattini et al where the binding constant for the corresponding pyrenyl system (1 þ 2) was calculated by UVvis spectroscopy to be to be 80 M À1 and also by Colquhoun and coworkers who demonstrated [47] that perylene bound more strongly than pyrene to a macrocyclic ether sulfone diimide by one order of magnitude.…”

“…Resonances associated with the perylenyl end-group are also seen to shift upfield and become broader in appearance. The complex pattern observed for the bound naphthyl and perylenyl proton resonances in the polymer blend arises from the range of different binding sequences [56,57] within the random co-polymer backbone (i.e. dimer, trimer, etc.)…”

“…However, there has been only limited investigation of the ability of other pelectron rich aromatics to form p-stacked complexes with naphthalene diimides. Perylene is known to form stable complexes with macrocyclic aromatic ether imide sulfones [47] and is an example of an alternative aromatic moiety which could be employed to form pep stacking interactions with chain-folding aromatic diimides to yield healable materials (Scheme 1).…”

Adducts between Dansylated Poly(propylene amine) Dendrimers and Anthracene Clips Mediated by ZnII Ions: Highly Efficient Photoinduced Energy Transfer

“…[3] This feature, coupled with the presence of coordinating moieties, has been exploited to host metal ions in the interior of dendrimers. [4,5] Molecular clips [6,7] are preorganized synthetic receptors in which the nature of the sidewalls and/or the substituents appended to the bridging units allow the tuning of their chemical properties, such as solubility, luminescence, redox potentials, and their affinity and selectivity towards specific substrates. They can mimic natural receptors and take advantage of multivalent weak interactions to exhibit strong and specific recognition of biologically relevant substrates.…”

A benzthiazole-based simple receptor in fluorescence sensing of biotin ester and urea

“…23 In contrast to the binding of small molecule urea, simple bis amide receptor is sometimes very efficient in sequence-specific binding of high molar mass copolyimides. 24 Our ongoing interest in the selective binding of biologically relevant species by our synthetic receptor inspired us to work on simple system which is easy to make for fluorometric detection of both biotin methyl ester and urea in common organic solvent. In relation to this, we report here the design, synthesis, and host-guest interaction of benzthiazole-based receptor 1 which shows significant increase in emission upon complexation of biotin methyl ester and urea in CHCl 3 containing 1% CH 3 CN.…”