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Macrocycle engineering is a key topic in supramolecular chemistry. When synthesizing a ring, one can obtain either complex mixtures of macrocycles of different sizes or a single ring if a template is utilized. Here, we unite these approaches along with post‐synthetic modifications to transform a single tether into multiple rings—up to five per tether. The macrocycles contain two bridged phenylpyridine ligands that are connected through a Pt atom, which defines the rings' shape, size, and host activity. All rings undergo redox reactions (between PtII and PtIV) that allow for large conformational changes. Their reactivity, together with their host performance, is a convenient way to control the capture and release of guests, to mediate ring transformations, and to control pseudorotaxane‐to‐pseudorotaxane conversions. This novel approach could serve to assemble other libraries of small ring molecules, create cyclic polymers bridged by responsive‐at‐metal nodes, and produce processable mechanically interlocked molecules. [ABSTRACT FROM AUTHOR]

Responsive photonic crystals have potential applications in mechanical sensors and soft displays; however, new materials are constantly desired to provide new innovations and improve on existing technologies. To address this, we report stretchable chiral nematic cellulose nanocrystal (CNC) elastomer composites that exhibit reversible visible color upon the application of mechanical stress. When stretched (or compressed) the colorless materials maintain their chiral nematic structure but the helical pitch is reduced into the visible region, resulting in coloration of the CNC‐elastomer composite. By increasing the percentage elongation of the material (ca. 50–300 %), the structural color can be tuned from red to blue. The color of the materials was characterized by reflectance optical microscopy and reflectance circular dichroism to confirm the wavelength and polarization of the reflected light. We also probed the mechanism of the structural color using 2D‐X‐ray diffraction. Finally, by either water‐patterning the starting CNC film, or by forming a CNC film with gradient color, through masked evaporation, we were able to prepare encoded stretchable chiral nematic CNC‐elastomers. [ABSTRACT FROM AUTHOR]

CO2 Fixation, Cellulose Nanocrystals (CNCs), Heterogeneous Catalyst, Microporous Organic Polymer (MOP), Zeolitic Imidazolate Framework (ZIF-8) Inside Cover: Uniform Growth of Nanocrystalline ZIF-8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers (Angew. Keywords: CO2 Fixation; Cellulose Nanocrystals (CNCs); Heterogeneous Catalyst; Microporous Organic Polymer (MOP); Zeolitic Imidazolate Framework (ZIF-8) EN CO2 Fixation Cellulose Nanocrystals (CNCs) Heterogeneous Catalyst Microporous Organic Polymer (MOP) Zeolitic Imidazolate Framework (ZIF-8) 1 1 1 06/06/23 20230612 NES 230612 B Cellulose nanocrystals b (CNCs) have been captured inside a zinc-containing microporous organic polymer (MOP) network through sacrificial templating with zeolitic imidazolate framework (ZIF-8) crystals. [Extracted from the article]

Cellulose nanocrystals (CNCs), known for more than 50 years, have attracted attention because of their unique properties such as high specific strength and modulus, high surface area, and fascinating optical properties. Just recently, however, their potential in supramolecular templating was identified by making use of their self-assembly behavior in aqueous dispersions in the presence of compatible precursors. The combination of the mesoporosity, photonic properties, and chiral nematic order of the materials, which are available as freestanding films, has led to a significant number of interesting and promising discoveries towards new functional materials. This Review summarizes the use of cellulose derivatives, especially CNCs, as novel templates and gives an overview of the recent developments toward new functional materials. [ABSTRACT FROM AUTHOR]

Post‐synthetic modification of mechanically interlocked molecules (MIMs) is an attractive avenue to add complexity to already intricate systems. This remains an important, challenging topic that is under‐developed. In this paper, we report the synthesis and characterization of a [2]rotaxane molecule featuring a ring appended to an emissive cyclometalated PtII unit. Modulation of the oxidation state at the metal center can transform the interlocked molecule into a new PtIV [2]rotaxane or a PtIII [3]rotaxane held together by an intermetallic Pt−Pt bond – a first of its kind. These molecules display distinct structural and photophysical properties, as well as shuttling dynamics. This approach for post‐synthetic modification could be used to construct more complex MIMs and inorganic supramolecular assemblies with redox properties. [ABSTRACT FROM AUTHOR]