Photo‐Induced Polymer Cyclization via Supramolecular Confinement of Cyanostilbenes

Abstract

Efficient synthesis of cyclic polymers has received much attention in polymer chemistry field. Although photochemical cycloaddition of terminal p-bonded units provides a plausible way toward cyclic polymerization, it remains challenging to avoid side reactions by manipulating the reaction selectivity. Herein supramolecular confinement has been developed as a promising strategy to address this issue, by introducing highly directional hydrogen bonds to the photoreactive cyanostilbenes. The cyanostilbenes units on both ends of a telechelic macromonomer are orientationally aligned with high local concentrations, yielding [2+2] photo-cycloaddition products upon 430 nm light irradiation. It leads to the formation of cyclic polymers in the self-assembled state, in stark contrast to Z-E isomerization of cyanostilbenes in the monomeric state. Overall, supramolecular confinement effect exemplified in the current study provides new avenues toward cyclic topological polymers with high synthetic efficiency.

Enhancing the Circularly Polarized Luminescence of Self‐assembled Cyanostilbenes through Extended π‐Conjugation

“…To ensure solubility in apolar solvents, we attached gallic wedges with n ‐dodecane side chains [ 8 ] to the peripheries of the designed compounds. Additionally, enantiopure N ‐[(1 S )‐phenylethyl]‐benzamides [ 9 ] were anchored adjacent to the cyanostilbene core, facilitating hydrogen bonding interactions between neighboring molecules. By combining intermolecular hydrogen bonding and π–π stacking interactions, the designed monomers were capable of assembling into long‐range‐ordered supramolecular polymers in toluene.…”

Dinuclear coumarin-containing alkynylplatinum(ii) terpyridine complexes with supramolecular assembly-assisted photodimerization

“…[42][43][44][45] In spite of the recent reports on solution-state photodimerization, [46][47][48][49] these studies have been mainly confined to the use of different host molecules to form host-guest adducts with coumarins through various non-covalent interactions such as hydrogen bonding, p-p stacking and hydrophobic interactions for the preorganization of coumarin monomers. [46][47][48][49] Although the confinement effect on different photoinduced dimerization behaviors has attracted much attention recently, 50 such preorganization of coumarin-containing molecules in solutions by supramolecular self-assembly of the coumarin monomers for their ready photodimerization is still rather limited and under-explored. 51 Since alkynylplatinum(II) terpyridine complexes have been found to have rich spectroscopic properties and a strong tendency to self-assemble through intermolecular PtÁ Á ÁPt and p-p stacking interactions due to their square-planar geometry, and by taking advantage of the directional non-covalent PtÁ Á ÁPt interaction, it is envisaged that with appropriate design, coumarin-containing platinum(II) complexes can be aligned for ready photodimerization, and the changes in the photophysical properties as well as the supramolecular assembly behaviors upon photoirradiation can be visualized.…”

Fluorescence Lifetime-Based Characterization for Supramolecular Polymer Molecular Weight

“…The molecular weight of polymers has a profound impact on their functional performance, physical properties, and processing characteristics. − Characterizing the molecular weight provides valuable insights into the properties of polymers. , In the case of conventional polymers, gel permeation chromatography is commonly used to directly measure molecular weight with precision , However, this method is not suitable for supramolecular polymers, which are a distinct type of polymer formed through noncovalent interactions. − Unlike covalent polymers, supramolecular polymers exhibit dynamic behavior, and their formation is highly dependent on concentration. − Supramolecular polymers exhibit a dynamic nature attributed to the presence of noncovalent interactions, which play a pivotal role in their assembly from monomeric units. Consequently, the formation of supramolecular polymers is highly dependent on concentration. − At lower concentrations, cyclic assemblies or oligomers prevail as the predominant species, while supramolecular polymers emerge at higher concentrations.…”