Pyrene-Based Asymmetric Supramolecule: Kinetically Controlled Polymorphic Superstructures by Molecular Self-Assembly

Abstract

To understand the kinetically controlled polymorphic superstructures of asymmetric supramolecules, a pyrene-based asymmetric supramolecule (abbreviated as Py3M) was newly synthesized by connecting two pyrene headgroups (Py) to a biphenyl-based dendritic tail (3M) with an iso­phthala­mide connector. On the basis of thermal, microscopic, spectroscopic, and scattering results, it was realized that Py3M exhibited the monotropic phase transition between a stable crystalline phase (K1) and a metastable crystalline phase (K2). This monotropic phase transition behavior was mainly originated from the competitions of intra- and intermolecular interactions (π–π interactions and hydrogen bonds) as well as from the nanophase separations. From the two-dimensional (2D) wide-angle X-ray diffraction patterns and transmission electron microscopy images of the self-assembled Py3M superstructures, it was found that Py3M formed two synclinically tilted crystalline superstructures: the 6.75 and 4.4 nm periodicities of layered structures for K1 and K2 phases, respectively. The stable K1 phase was predominantly induced by the π–π interactions between pyrenes, while the intermolecular hydrogen bonds between iso­phthala­mides were the main driving forces for the formation of the metastable K2 phase. Ultraviolet–visible and photoluminescence experiments indicated that the photophysical properties of Py3M were directly related to their molecular packing superstructures.

Novel Luminescent Ionic Adducts Based on Pyrene-1-sulfonate

“…21,54−56 On the basis of our experimental findings, it is reasonable to suppose that as solids, Imi–PS can be organized in supramolecular structures, via the alkyl chain, which can undergo “order–disorder” or vice versa phase transitions, thus affording nonreversible heating/cooling cycles and different DSC scanning profiles at different heating rates. 57 On the other hand, recent reports have described the role played by pyrene moieties in promoting and controlling the polymorphic superstructures of asymmetric dendritic biphenyl-based supramolecules. 57 Our DSC data suggest that (i) the thermal transition phase behavior of POSS–PS is still determined by the bulky amphiphilic nature of the trimethylpropylammonium hepta(isooctyl) octasilsesquioxane cation 39 and (ii) the substitution of bromide with a PS anion produces significant modifications on imidazolium-ILs, in terms of the melting point increase and the overall DSC thermogram profiles.…”

Asymmetric Fullerene Nanosurfactant: Interface Engineering for Automatic Molecular Alignments

“…Bright‐field TEM images of C 60 NS films are shown in Figure b. Alternative dark and bright stripes are observed owing to the disparity in electron density of the fullerene‐rich and the cyanobiphenyl‐rich phase . The diffused reflection at 0.92 nm was attributed to the interaction between partially ordered states of C 60 moieties, whereas the broad halo in the wide‐angle region centered at 0.46 nm was ascribed to the lateral molecular packing of mesogenic groups .…”

Programmed Hierarchical Hybrid Nanostructures from Fullerene‐Dendrons and Pyrene‐Dendrons

“…As shown in Scheme , the rigid biphenyl‐based LC dendron (R) with amphiphilic flexible side chains (hydrophobic alkyl and hydrophilic ethylene oxide chains) were chemically linked to C 60 . To assist the construction of hierarchical nanostructures of C 60 D, the pyrene‐based tweezer‐like asymmetric dendron (PD) with three biphenyl‐based LC groups was additionally prepared . Owing to distinct natures between the amphiphilic dendrons and the π‐conjugated C 60 , C 60 D can exhibit strong nanophase separation at molecular scale and tend to form into a layer structure .…”

“…Once the PD host molecules are introduced, the self‐assembled buckle‐like supramolecules (C 60 D·PD) can be formed by host–guest binding between C 60 D and PD. The C 60 D and PD compounds were obtained via the Bingel reaction and the amidation coupling, respectively . The detailed synthetic information of C 60 D and PD is outlined in Figure S1 (Supporting Information).…”

“…To demonstrate this concept, monofunctionalized C 60 dendron (C 60 D, guest) was newly designed and synthesized in this research by attaching three biphenyl‐based LC groups. The pyrene‐based tweezer‐like asymmetric dendron (PD, host) with three biphenyl‐based LC groups was also prepared by following our previous research . Since the π‐conjugated system of pyrene is a sufficient electron donating moiety and the C 60 ‐based compounds are electron acceptors, the PD host molecule can effectively capture the C 60 D guest molecule by charge transfer complexes.…”