Thiacalixarenes

Noncovalent Interactions Accompanying Encapsulation of Resorcinol within Azacalix[4]pyridine Macrocycle

Electronic structure and noncovalent interactions within the inclusion complexes of resorcinol and calix[4]pyridine (CXP[4]) or azacalix[4]pyridine (N-CXP[4]) macrocycles have been analyzed by employing hybrid M06-2X density functional theory. It has been demonstrated that substitution of a heteroatom (-NH-) at the bridging position of the CXP[4] alters the shape of the cavity from a "box-shaped" to funnel-like one. Penetration of resorcinol guest within the CXP[4] cavity renders a "butterfly-like" structure to the complex, whereas the N-CXP[4] complex reveals distorted geometry with the guest being nearer to one of the pyridine rings at the upper rim of the host. Underlying hydrogen bonding, π···π, and other weak interactions are characterized using the Quantum Theory of Atoms in Molecules (QTAIM) and Noncovalent Interactions Reduced Density Gradient (NCI-RDG) methods. The coexistence of multiple intermolecular interactions is envisaged through the frequency shifts of the characteristic -NH and -OH vibrations in their calculated vibrational spectra. The guest protons confined to the host cavity exhibit shielding, while those facilitating hydrogen bonding engender the downfield signals in their calculated ¹H NMR spectra.

Synthesis of hydroxylated azacalix[1]arene[3]pyridines from hydrolysis of high valent arylcopper complexes and conversion to a double azacalix[1]arene[3]pyridine host molecule

Arylcopper(ii) compounds reacted efficiently with KOH at ambient temperature to produce exclusively lower-rim-hydroxylated azacalix[1]arene[3]pyridines which underwent further CuCl₂/TMEDA-catalyzed oxidative homocoupling to afford an unprecedented bisazacalix[1]phenol[3]pyridine host molecule.

Straightforward metal-free synthesis of an azacalix[6]arene forming a host–guest complex with fullerene C60

The straightforward metal-free synthesis of an azacalix[6]arene from simple aryl units is described together with its full characterization. This macrocycle features a rare 1,2,4,5-alternate conformation and is able to form a 1 : 1 stable host–guest complex with C₆₀.

Synthesis and conformational structure of hydrazo-bridged homo calix[2]pyridine[2]triazines

Presented in this paper are the practical synthesis and conformational structure of hydrazo-bridged homo calix[4]arenes.

Unexpected cleavage of thiacalix[4]arene sulfoxides

Thiacalix[4]arene monosulfoxides possess an unprecedented reactivity towards n-BuLi to form unusual linear structures.

Synthesis, crystal structure and remote allosteric binding properties of cone thiacalix[4]pseudocrown receptors bearing anthraquinone function and different arms

Herein, three novel cone thiacalix[4]pseudocrown receptors 1–3, bearing anthraquinone and triazole functions as well as different side arms, were successfully synthesized via a double click reaction as the key step.

How the electron-deficient cavity of heterocalixarenes recognizes anions: insights from computation

The nature of bridging heteroatoms in a heterocalixarene structure has a crucial role in anion recognition.

Calix[n]arene-based polyradicals: enhancing ferromagnetism by avoiding edge effects

The absence of edges in circular structures derived from 1,3-arylmethyl polyradical results in realistic molecules showing largely stabilized high-spin ground states.

Promising advances of thiacalix[4]arene in crystal structures

Thiacalix[4]arenes are one kind of robust scaffolds and extensively applied in supramolecular chemistry and materials science owing to their novel features.

14,16,34,36,54,56,74,76-Octanitro-2,4,6,8-tetraoxa-1,3,5,7(1,3)-tetrabenzenacyclooctaphane and its derivatives: thermally stable explosives with outstanding properties

Herein, the novel, thermally stable explosive 1⁴,1⁶,3⁴,3⁶,5⁴,5⁶,7⁴,7⁶-octanitro-2,4,6,8-tetraoxa-1,3,5,7(1,3)-tetrabenzenacyclooctaphane (4a) and its derivatives are reported.

Pillar-Shaped Macrocyclic Hosts Pillar[n]arenes: New Key Players for Supramolecular Chemistry

In 2008, we reported a new class of pillar-shaped macrocyclic hosts, known as "pillar[n]arenes". Today, pillar[n]arenes are recognized as key players in supramolecular chemistry because of their facile synthesis, unique pillar shape, versatile functionality, interesting host-guest properties, and original supramolecular assembly characteristics, which have resulted in numerous electrochemical and biomedical material applications. In this Review, we have provided historical background to macrocyclic chemistry, followed by a detailed discussion of the fundamental properties of pillar[n]arenes, including their synthesis, structure, and host-guest properties. Furthermore, we have discussed the applications of pillar[n]arenes to materials science, as well as their applications in supramolecular chemistry, in terms of their fundamental properties. Finally, we have described the future perspectives of pillar[n]arene chemistry. We hope that this Review will provide a useful reference for researchers working in the field and inspire discoveries concerning pillar[n]arene chemistry.

Straightforward Synthesis, Electrochemical Properties, and Gel Formation of Thiacalix[n]thiophenes

A facile synthetic approach toward thiacalix[n]thiophene homologues (n=4-6) is presented herein. Pd-catalyzed coupling of 2,5-dibromothiophene derivatives with stannyl sulfide gave various thiacalix[n]thiophenes in good yields. The optical and electrochemical properties of the produced cavitands were investigated. Furthermore, gelation was observed in some solvents.

N,N,N-Triethylethanaminium 5,11,17,23-tetra-tert-butyl-25-cyanomethoxy-26,28-dihydroxy-27-oxido-2,8,14,20-tetrathiacalix[4]arene: a molecular salt

In the title molecular salt, C8H20N+·C42H48NO4S4−, the conformation of the anionic tetrathiacalix[4]arene, which is cone-shaped, is primarily determined by intramolecular O—H...O hydrogen bonds. There are also intramolecular C—H...O short contacts present. In the crystal, the anions (A) and cations (C) are linked by C—H...O and C—H...S hydrogen bonds, forming –A–C–A–C– chains along [001]. The chains are linkedviaC—H...Ncyanohydrogen bonds, forming ribbons along [001].

Self-induced organic guest packed in three-dimensional architecture based on hetero-alkali metallic sulfonatothiacalix[4]arene

Inclusion behavior of pyridine N-oxide in the cavity of hetero-alkali metallic sulfonatothaicalix[4]arene was studied by single crystal X-ray diffraction studies. π–π stacking, S–π interactions and hydrogen bonding were mainly supported this complex.

A study of anion binding behaviour of 1,3-alternate thiacalix[4]arene-based receptors bearing urea moieties

Thiacalix[4]arene receptors with two urea moieties exhibited a high affinity towards all of the selected anions.

Designing structurally tunable and functionally versatile synthetic supercontainers

A new family of flexible metal–organic supercontainers exhibit selective binding with cationic guests and tunable supramolecular catalytic activity.