Amphiphilic Porphyrin Nanocrystals: Morphology Tuning and Hierarchical Assembly

Abstract

The translation of molecular building blocks into welldefined solid-state structures in a hierarchical fashion (i.e., molecular scale ! nanoscale ! meso-and macroscale) is a key process in many bottom-up materials syntheses. Recent applications of this concept have resulted in new classes of materials that possess well-defined nanometer-sized domains that effect selective catalysis [1] and separation, [2] enable gas storage, [3,4] and facilitate energy transfer.[5] However, assembling such domains into mesoscopic [6,7] or even macroscopic structures remains a major challenge. As the properties of nanomaterials created from small inorganic and organic building blocks can be readily tuned at a molecular level, much interest has been devoted to the assembly of these materials into ever-larger structures. Herein, we demonstrate a hierarchical strategy for producing mesoscopic (and larger) objects from discrete amphiphilic porphyrins. Crystal growth under highly ''energetic'' conditions (i.e., vigorous stirring and heating) was first employed to produce, in a scalable fashion, uniform nanocrystals the morphology of which can be easily modulated by crystal growth conditions as well as the structure of the porphyrin building blocks. These materials were then assembled into macroscopic prisms in the presence of a simple surfactant or selectively partitioned into hydrophobic patterns on glass surfaces. Because the porphyrin nanocrystals formed in the first step have enhanced photostability compared to their molecular constituents, the described hierarchical method for assembling them into larger objects should facilitate practical applications of porphyrin-based materials in transport, [8] imaging, [9] light-harvesting, [10] or catalysis.

Porphyrin Supramolecular 1D Structures via Surfactant‐Assisted Self‐Assembly

“…Besides the good controllability, good reproducibility, and operational simplicity, one of the most important merits of SAS is its strong capability for hierarchical assembly, wherein the in situ fabricated or prefabricated nanostructures can be further organized to form meso‐ or even macroscale structures . Lee et al reported that nanoplates of amphiphilic (porphyrin)Sn molecules, which were prefabricated via a surfactant‐free mixed‐solvent‐induced self‐assembly, and were featured with both hydrophilic and hydrophobic faces, could be further organized to form macroscopic structures in the presence of surfactants . They showed that exposing the nanoplates to CTAB, followed by a microwave‐irradiation treatment, could lead to the formation of micrometer‐sized triangular 1D columns, whose size and aspect ratio could be tuned by the CTAB concentration.…”

Organic Nanocrystals of the Resorcinarene Hexamer via Sonochemistry: Evidence of Reversed Crystal Growth Involving Hollow Morphologies

“…18,22–26 The CMCR crystals described here are the first reported hollow, polyhedral crystals composed of purely organic components. 27 The formation of the hollow crystals is attributed to a reversed crystal growth mechanism recently elucidated by Zhou et al to account for the formation of hollow zeolite and perovskite crystals. 28–31 The stages of reversed crystal growth include oriented aggregation of nanoparticles, surface recrystallization, and growth from the surface-to-core.…”

Arginine-Mediated Self-Assembly of Porphyrin on Graphene: A Photocatalyst for Degradation of Dyes

“…Supramolecular nanostructures via self-assembly are usually produced via non-covalent interactions such as hydrogen bonding, electrostatic, van der Waals interactions, π-π interactions, and coordination. These soft materials are fabricated by self-assembly protocols including ionic self-assembly [14], surfactant-assisted self-assembly (SAS) [15], and reprecipitation [16,17]. Many well-defined and controlled nanostructures such as nanoprisms, nanotubes, nanofibre bundles, nanorods, nanosheets, nanospheres, nanoclovers, nanowires and nanoparticles have thus been reported [14,16,[18][19][20][21][22].…”