Tailored Combinatorial Microcompartments through the Self‐Organization of Microobjects: Assembly,Characterization, and Cell Studies

A new concept enables the generation of cell microenvironments by microobject assembly at an water/air interface. As the orientation of 30 μm sized polymer cubes and their capillary force assembly are controlled by the surface wettability, which in turn can be modulated by coating the initially exposed surfaces with gold and self‐assembled monolayers, unique niches in closely packed arrays of cubes with vertex up orientation can be realized. The random assembly of distinctly different cubes, prefunctionalized or surface‐structured exclusively on their top surface, facilitates the parallel generation of different microenvironments in a combinatorial manner, which paves the way to future systematic structure–property relationship studies with cells.     

A Chiral Recognition System Orchestrated by Self‐Assembly: Molecular Chirality,Self‐Assembly Morphology,and Fluorescence Response

The newly developed oligophenylenevinylene (OPV)‐based fluorescent (FL) chiral chemosensor (OPV‐Me) for the representative enantiomeric guest, 1,2‐cyclohexanedicarboxylic acid (1,2‐CHDA: RR ‐ and SS ‐form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV‐Me self‐assembly: RR ‐CHDA directed the fibrous supramolecular aggregate, whereas SS ‐CHDA directed the finite aggregate. The consequent FL intensity toward RR ‐CHDA was up to 30 times larger than that toward SS ‐CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV‐Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self‐assembly.     

Oriented Gold Nanorod Arrays: Self‐Assembly and Optoelectronic Applications

Self‐assembly of anisotropic plasmonic nanomaterials into ordered superstructures has become popular in nanoscience because of their unique anisotropic optical and electronic properties. Gold nanorods (GNRs) are a well‐defined functional building block for fabrication of these superstructures. They possess important anisotropic plasmonic characteristics that result from strong local electric field and are responsive to visible and near‐IR light. There are recent examples of assembling the GNRs into ordered arrays or superstructures through processes such as solvent evaporation and interfacial assembly. In this Minireview, recent progress in the development of the self‐assembled GNR arrays is described, with focus on the formation of oriented GNR arrays on substrates. Key driving forces are discussed, and different strategies and self‐assembly processes of forming oriented GNR arrays are presented. The applications of the oriented GNR arrays in optoelectronic devices are also overviewed, especially surface enhanced Raman scattering (SERS).     

Blockable Zn10L15 Ion Channels through Subcomponent Self‐Assembly

Metal–organic anion channels based on Zn₁₀L₁₅ pentagonal prisms have been prepared by subcomponent self‐assembly. The insertion of these prisms into lipid membranes was investigated by ion‐current and fluorescence measurements. The channels were found to mediate the transport of Cl⁻ anions through planar lipid bilayers and into vesicles. Tosylate anions were observed to bind and plug the central channels of the prisms in the solid state and in solution. In membranes, dodecyl sulfate blocked chloride transport through the central channel. Our Zn₁₀L₁₅ prism thus inserts into lipid bilayers to turn on anion transport, which can then be turned off through addition of the blocker dodecyl sulfate.     

Self‐Assembly of Conjugated Metallopolymers with Tunable Length and Controlled Regiochemistry

Self‐assembled materials can be designed to express useful optoelectronic properties; however, achieving structural control is a necessary precondition for the optimization of desired properties. Here we report a simple, metal‐templated polymerization process that generates helical metallopolymer strands over 75 repeat units long (28 kDa) from a single bifunctional monomer and Cu^I. The resulting polymer consists of a double helix of two identical conjugated organic strands enclosing a central column of metal ions. The length of this metallopolymer can be controlled by adding monofunctional subcomponents to end‐cap the conjugated ligands. The use of ditopic and bulky monotopic subcomponents, respectively, allows a head‐to‐head or head‐to‐tail double helix to be generated. Spectroscopic measurements of different polymer lengths demonstrate how control over polymer length leads to control over the electronic and luminescent properties of the resulting material, thereby enabling tunable white‐light emission.     

Photoresponsive Nanosheets of Polyoxometalates Formed by Controlled Self‐Assembly Pathways

Anionic Keggin polyoxometalates (POMs) and ether linkage‐enriched ammonium ions spontaneously self‐assemble into rectangular ultrathin nanosheets in aqueous media. The structural flexibility of the cation is essential to form oriented nanosheets; as demonstrated by single‐crystal X‐ray diffraction measurements. The difference in initial conditions exerts significant influence on selecting for self‐assembly pathways in the energy landscape. Photoillumination of the POM sheets in pure water causes dissolution of reduced POMs, which allowed site‐specific etching of nanosheets using laser scanning microscopy. By contrast, photoetching was suppressed in aqueous AgNO₃ and site‐selective deposition of silver nanoparticles occurred as a consequence of electron transfer from the photoreduced POMs to Ag⁺ ions on the nanosheet surface.