A contorted nanographene shelter

Abstract

Nanographenes have kindled considerable interest in the fields of materials science and supramolecular chemistry as a result of their unique self-assembling and optoelectronic properties. Encapsulating the contorted nanographenes inside artificial receptors, however, remains challenging. Herein, we report the design and synthesis of a trigonal prismatic hexacationic cage, which has a large cavity and adopts a relatively flexible conformation. It serves as a receptor, not only for planar coronene, but also for contorted nanographene derivatives with diameters of approximately 15 Å and thicknesses of 7 Å. A comprehensive investigation of the host-guest interactions in the solid, solution and gaseous states by experimentation and theoretical calculations reveals collectively an induced-fit binding mechanism with high binding affinities between the cage and the nanographenes. Notably, the photostability of the nanographenes is improved significantly by the ultrafast deactivation of their excited states within the cage. Encapsulating the contorted nanographenes inside the cage provides a noncovalent strategy for regulating their photoreactivity.

A π-Electron Rich Cage via the Friedel–Crafts Reaction

“…The structure of cage 1 is reminiscent of those reported by Stoddart et al, called the blue cage or the Excage . Compared to the Excage, synthesis of which relies on a two-step irreversible S N 2 reaction, the synthesis of cage 1 is evidently more beneficial in terms of the formation of six C–C bonds in a one-pot fashion based on the relevantly reversable FC reaction.…”

“…One of the major focuses in the field of supramolecular chemistry is the construction of host molecules with preorganized cavities, where guest molecules are accommodated, and the properties of these guests may be switched relative to those in bulk solutions. − Earlier approaches used in the synthetic protocols, such as the Williamson reaction in the synthesis of crown ethers , and the S N 2 reaction in the preparation of a variety of pyridinium-containing rings and cages, − and other N -containing prism cages, often rely on the formation of irreversible bonds. In the ring closure steps of such reactions, the macrocyclic target products are often or always accompanied by a variety of oligomeric and polymeric byproducts.…”

“…The structure of cage 1 is reminiscent of those reported by Stoddart et al, called the blue cage 13 or the Excage. 14 Compared to the Excage, synthesis of which relies on a twostep irreversible S N 2 reaction, the synthesis of cage 1 is evidently more beneficial in terms of the formation of six C−C bonds in a one-pot fashion based on the relevantly reversable FC reaction. In addition, the formation of cage 1 does not require any template for its synthesis, almost certainly because the FC reaction allows error checking to suppress the formation of byproducts.…”

The Green Box: Selenoviologen-Based Tetracationic Cyclophane for Electrochromism, Host–Guest Interactions, and Visible-Light Photocatalysis

“…Cationic cyclophane as novel macrocyclic hosts has been widely used in host–guest chemistry, − mechanically interlocked molecules, − luminescent materials, − drug delivery, − molecular catalysis, − and other fields due to their advantages of the rigid cavity, excellent electron-deficient, good redox properties, and so on. − Especially, cyclobis­(paraquant- p -phenylene), also known as the blue box ( 1 ), was developed by Stoddart and co-workers, which exhibited excellent applications in supramolecular architectures, host–guest complexes, catalysis, and mechanically interlocked molecules during the past 35 years. − Inspired by this, some novel box-like derivatives have been reported . For example, Stoddart and co-workers designed and synthesized the tetrazine box, a structurally transformative tetrazine-containing tetracationic cyclophane, existing in three different reversible redox states which can be manipulated and visited by delicately controlled redox chemistry .…”

Photoreactive CO2 Capture by a Zr-Nanographene MOF

“…Component 1 is assigned to vibrationally "hot" S1 excited state which undergoes vibrational relaxation to the S1 state with an 8.1 ps lifetime. 56 Based on this assignment, we hypothesize that the photochemical CO2 reduction is initiated by ligand-centered excited-states, as illustrated in Scheme 2. Based on the experimental and computational studies described above, the mechanism for photochemical CO2 Second, the proposed mechanism combines CO2 capture with its direct conversion to value-added products, in a process we name "photoreactive capture".…”