Electron Hopping and Charge Separation within a Naphthalene-1,4:5,8-bis(dicarboximide) Chiral Covalent Organic Cage

Abstract

We present the stereoselective synthesis of a chiral covalent organic cage consisting of three redox-active naphthalene-1,4:5,8-bis(dicarboximide) (NDI) units by dynamic imine chemistry. Single crystal X-ray diffraction analysis shows that host-guest interactions and racemic cocrystallization allow for controlling the solid state structure. Electronic interactions between the NDI units probed by absorption and circular dichroism spectroscopies, electrochemistry and theoretical calculations are shown to be weak. Photoexcitation of NDI leads to intracage charge separation with a longer lifetime than observed in the corresponding monomeric NDI and dimeric NDI cyclophane imines. The EPR spectrum of the singly reduced cage shows that the electron is localized on a single NDI unit at ambient temperatures and transitions to rapid hopping among all three NDI units upon heating to 350 K. Dynamic covalent chemistry thus promises rapid access to covalent organic cages with well-defined architectures to study charge accumulation and electron transport phenomena.

Elucidating heterogeneous photocatalytic superiority of microporous porphyrin organic cage

“…The similar triplet quantum yield for PTC-1(2H) to that of H 2 CBPP, however, is qualitatively unveiled by their similar absolute fluorescence quantum yield and lifetime 60 , while the triplet lifetime (102.20 μs) for this cage is almost twice longer than that of monomer (53.98 μs), which is associated with the much more rigid structure of the cage molecule ( Fig. 4b) 61 . This result suggests the existence of much more reaction opportunities between the triplet excited states of cages and 3 O 2 molecules, being helpful for the photo-inducing evolution of ROS.…”

Perylene Diimide Based Imine Cages for Inclusion of Aromatic Guest Molecules and Visible‐Light Photocatalysis

“…542 nm increased gradually, and the fluorescent emission of guest molecules (perylene, λ em =505 nm) also became stronger with the addition of guest. In the present fluorescence enhancement, guest perylene or triphenylene molecules binding with PDI units may block the photoinduced hopping among the PDI units, preventing structural relaxation in the excited state towards intercage PDI‐PDI coupling (Figure b) …”

“…Efforts to more structure variation and visible‐light‐driven reactions are currently underway. Additionally the original chirality of cyclohexanediamine moieties has been maintained in the large imine cage structures probably via the formation of a helical twist, and the cages provide a large cavity that allows large substrates to fill in and are promising to act as chiral catalysts for photoredox reactions with large substrates.…”

“…Much attention has been recently focused on supramolecular assemblies based on perylene and naphthalene tetracarboxylic diimides (PDIs, NDIs) due to their strong intermolecular π‐π stacking interaction, easy functionalization, unique optical and electrochemical properties . In comparison with NDI derivatives, PDI derivatives are of great interest because they show the capability to absorb a wide range of light energy and show intense absorption of visible light with electron deficient character . Although PDI derivatives have been used as large rigid and planar scaffold and incorporated in macrocyclic molecules, PDI units have rarely been incorporated in discrete cage architectures .…”

Synthesis of a sucrose-based macrocycle with unsymmetrical monosaccharides "arms"

“…Binaphthols [ 7 – 9 ], amino acids [ 10 ], chiral diamines [ 11 – 12 ], carbohydrates [ 13 ], etc. are usually applied as building blocks for construction of such type of compounds.…”