Kinetically Controlled Assembly of a Spirocyclic Aromatic Hydrocarbon into Polyhedral Micro/Nanocrystals

Abstract

Nonplane molecules with multiple large aromatic planes could be promising candidates to form various polyhedral micro/nanocrystals by manipulating the different π···π stacking, tuning the cohesive energies of crystal facets, and controlling the kinetic growth process. Spirocyclic aromatic hydrocarbons (SAHs) not only have two cross-shaped aromatic planes but also offer the feature of supramolecular steric hindrance, making it favorable for the heterogeneous kinetic growth into highly symmetric polyhedra. Herein, we report that a novel SAH compound, spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO), can self-assemble into various monodispersed shapes such as hexahedra, octahedra, and decahedra through the variation of either different types of surfactants, such as Pluronic 123 (P123) and cetyltrimethyl ammonium bromide (CTAB), or growth parameters. In addition, the possible mechanism of crystal facet growth has been proposed according to the SEM, XRD, TEM, and SAED characterization of organic polyhedral micro/nanocrystals. The unique cruciform-shaped SAHs have been demonstrated as fascinating supramolecular synthons for various highly symmetric polyhedral assembling.

SMART Design of a Bulk‐Capped Supramolecular Segment for the Assembly into Organic Interdigital Lipid Bilayer‐Like (ILB) Nanosheets

“…Compared with the surfactant‐free counterparts (≈8 ± 2 µm in length, 4 ± 1 µm in width), the average side length of surfactant‐assisted TPA‐PF nanosheets is one‐magnitude‐order longer as disclosed in Figure e (≈100 ± 8 µm in length, 40 ± 10 µm in width). The solubilization effect of P123 is supposed to be the reason that influences the size of the TPA‐PF nanosheets . With 1 H NMR spectra and fourier transform infrared spectroscopy (FTIR) analysis of the 2D nanosheets and the pure TPA‐PF molecules (see Figures S5 and S6, Supporting Information), we confirm that these two samples exhibit same 1 H NMR and FTIR spectra without any peaks from P123, ruling out the possibility of inclusion or encapsulation of P123 to the nanosheets.…”

Alignment of Organic Semiconductor Microstripes by Two‐Phase Dip‐Coating

“…At the same time, a certain amount of CTAB can diffuse from water into the chloroform solution, which is supposed to change the cohesive energy of conjugated molecules, determine their crystal facet growth and subsequently induce molecular crystallization on the substrate. The surfactant exhibits a crucial role for the crystal shape, as shown by the two experiments in Figures a and S6 . Direct dip‐coating from DFCO‐4T chloroform solution with 0.1 mg/mL CTAB causes the formation of diamond‐shaped crystals, in comparison to rectangular ones without surfactant.…”

“…There is clear evidence that the growth kinetics of conjugated molecules are strongly dependent on a variety of parameters such as solvent, concentration, temperature and surfactant . Surfactants are common in the field of nanostructure fabrication to change the cohesive energy and determine the competition of crystal facet growth of organic molecules .…”

“…There is clear evidence that the growth kinetics of conjugated molecules are strongly dependent on a variety of parameters such as solvent, concentration, temperature and surfactant . Surfactants are common in the field of nanostructure fabrication to change the cohesive energy and determine the competition of crystal facet growth of organic molecules . Because of the colloidal stability and/or selective adhesion on certain facets of the surfactant, a high variety of nanoscale objects including cubes, cubooctahedrons, octahedrons and even fullerene‐encapsulated rods can be assembled by manipulating the nucleation and the subsequent growth kinetics of conjugated molecules.…”

Self‐Assembly of a β‐Peptide Foldamer: The Role of the Surfactant in Three‐Dimensional Shape Selection

“…Several studies on surfactant-assisted synthesis of organic crystals, including one of our recent studies, attributed 3D shape selection to the facet-specific adhesion of surfactant molecules and anisotropic passivation effect. [11e, [18][19][20][21] However, the inherent dynamic nature of surfactant molecules hinders a clear rationalization of 3D shape evolution and the corresponding assembly mechanisms. [22] In this study, we systematically investigated the mechanism of anisotropic growth of foldectures and molecular-level interactions between β-peptides and surfactants using experimental and computational approaches.…”