A series of triazolecarboxamide-containing foldamers were synthesized from simple starting materials by means of repeated [3+2] cycloadditions) and acid–amine coupling reactions. Foldamer–anion binding behavior and affinities were determined by ¹H NMR titration in [D₂]dichloromethane. The selective recognition of sulfate by these motifs was studied by one- and two-dimensional (¹H, ¹H-¹H COSY and NOESY) NMR spectroscopy as well as UV/Visible and fluorescence titrations. The structures of the triazolecarboxamide-containing foldamers can be optimized for highly selective recognition of sulfate anions by changing the numbers of triazolecarboxamide units and by the introduction of electron-withdrawing substituents on the terminal benzene ring. These findings indicate the importance of the structural compatibility between the receptor and anions for the highly selective anion binding as well as the electronic effect on tuning the anion-binding affinities of receptors.

The aim of this article is to summarize the recent advances in the synthesis of functional systems based on Cu^I-catalyzed azide-alkyne cycloaddition reaction. This reaction has the ability to exclusively afford 1,4-disubstituted 1,2,3-triazoles regioselectively, which have several features. First, such triazoles have a polarized CH bond, which could be used as a H-bond donor. Second, its atom arrangement and electronic properties are similar to those of a peptide bond, making it a candidate for an amide surrogate. Third, it has three nitrogen atoms, two of which could be used as coordinating sites for metal ions. Based on these features, 1,2,3-triazoles have potential applications in the construction of supramolecular functional systems. The design and synthesis strategies for anion receptors, bioactive macrocycles, and molecular machines are reviewed here. And in this scope we focus on foldamer-based receptors, macrocycle-based receptors, macrocyclic carbohydrates, macrocyclic peptides, catenanes, and rotaxanes.

A perylenetetracarboxdiimide derivative containing an anthraquinone unit has been synthesized by the phototriggered intramolecular cyclization of 2-anthraquinone-substituted perylenetetracarboxdiimide. The anthraquinone-substituted perylenetetracarboxdiimide dyes showed excellent electron-accepting abilities with four reversible reduction potentials. Photovoltaic devices of ITO/PEDOT:PSS/P3HT:PDIs/Ca/Al were fabricated and power conversion efficiencies of 0.16 and 0.39 were obtained for 1 and 2, respectively.

Amino-substituted pyrrole-fused perylenebis(dicarboximides) have been prepared from tri- or tetrabromoperylene prcursors by using the classical azidation conditions for the substitution of aromatic halogen, that is, NaN₃, sodium ascorbate, CuI, and N,N-dimethylethane-1,2-diamine in DMSO/H₂O. The pyrrole-fused dyes are highly photochemically and thermally stable, which may be useful for labelling and as building blocks for the synthesis of functional molecular materials.

A new supramolecular species of naphthalene-diimide cyclophane containing triazole units was synthesized, and its fluorescent responses to metal ions were investigated in dichloromethane (DCM). The fluorescence emission of NDI was quenched by intramolecular electron transfer, whereas the appearance of dimer emission of the naphthalene-diimide in the presence of Mg²⁺, Ba²⁺, Hg²⁺, Ca²⁺, Zn²⁺ and Pb²⁺ was observed.

The synthesis of 1,10-dihydroxyperylene bisimides by nucleophilic substitution of brominated perylene bisimide is described. 1,10-Dihydroxyperylene bisimides formed J aggregates in nonpolar solvents and showed a clearly redshifted absorption band. The solvent polarity also influenced the hydrogen bond with the hydroxyl group, and thus, the photophysical properties of perylene bisimide. The photophysical properties of these dihydroxyperylene perylene bisimides can also be tuned by changing charge transfer from the hydroxyl groups to the perylene core through the introduction of metal ions.

A new p-phenylenevinylene-linked perylene diimide has been synthesized and self-assembled for the formation of zero-dimensional molecular aggregate structures of nanospheres and vesicles through solvent tuning. The solid-state optical properties induced by a special wavelength laser were studied and the results indicated excellent fluorescent enhancement properties. The emission intensity of these aggregates increased with elongation of the laser irradiation time. Based on the analysis of variable-temperature ¹H NMR spectra, DFT calculations, and the single-crystal structure of the linkage group, a conformation-dependent fluorescent enhancement mechanism could be demonstrated. The mechanism is different from the fluorescent bleaching of normal solid-state fluorescent materials and offers potential applications in optical devices.

The design and synthesis of efficient receptors for tetrahedral oxyanions is an emerging field in supramolecular chemistry. Herein, we have developed a urea-like anion-recognizing motif, amidetriazole, which can be easily synthesized and derived and shows good solubility. A series of simple acyclic receptors were designed and synthesized to confirm the potential of amidetriazole for the construction of tetrahedral oxyanion receptors. This molecular platform can be used extensively for the construction of numerous receptor systems appended with functional groups, which opens the way to many applications in the field of supramolecular chemistry.

Peripheral donor-substituted N,N-dimethyl-4-[(7-nitrobenzo[c][1,2,5]thiadiazol-4-yl)ethynyl]aniline (1a), 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)-N,N-dimethylaniline (1b), and 4,4′-{benzo[c][1,2,5]thiadiazole-4,7-diylbis(ethyne-2,1-diyl)}bis(N,N-dimethylaniline) (2) were prepared by Sonogashira cross-coupling reactions. Compounds 1a, 1b, and 2 subsequently reacted with tetracyanoethylene (TCNE) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) to afford the charge-transfer chromophores 3–8. X-ray crystallographic analysis revealed the nonplanarity of these donor–acceptor (D–A) chromophores. Cyclic voltammetry (CV) exhibited a multistep reduction wave. UV/Vis spectra and theoretical calculations identified efficient intramolecular charge-transfer interactions. Moreover, scanning electron microscopy (SEM) showed the morphology transition and reconstruction process of 5 from 0D hollow nanospheres to 1D tubular microstructures.

The mild and highly efficient thiol-ene click reaction has been used to construct a rotaxane incorporating dibenzo-24-crown-8 (DB24C8) and a dibenzylammonium-derived thread in high yield under the irradiation of UV light. A rotaxane containing a disulfide linkage in the macrocycle was also synthesized by the thiol-ene click reaction. It has been demonstrated that the formation of the [2]rotaxane with the disulfide bond in the macrocycle occurs by a mechanism that is different to the threading-followed-by-stoppering process. The successful construction of a rotaxane directly from its constituent components, the macrocycle containing a disulfide linkage and the dibenzylammonium hexafluorophosphate salt, suggests that the space within the macrocycle incorporating the disulfide linkage is smaller than the phenyl unit and a plausible reaction mechanism has been proposed as follows: A small amount of the initiator forms two radicals upon the absorption of UV irradiation; the radicals act as a “key” to “unlock” the disulfide bond in the macrocycle. The resulting crown ether like moiety in the macrocycle is clipped around the ammonium ion center in the dumb-bell-shaped compound. The [2]rotaxane is generated upon recombination of the disulfide linkage.

Although many cagelike molecules can create a catalytic environment for promoting chemical reactions, the construction of receptors that can host anionic species and sensitize their reaction is novel. Here we report the photochemically induced dimerization of the anion radicals of TCNQ (7,7,8,8-tetracyano-para-quinodimethane) in organic solvent under aerobic conditions when they are encapsulated inside a cationic photoactive receptor. There is clear evidence for a rate increase of over two orders of magnitude, photosensitization of the host, and demonstrated turnover of the catalyst.