Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

The first continuous flow method was developed for the synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin starting from native β-cyclodextrin through three reaction steps, such as monotosylation, azidation and reduction. All reaction steps were studied separately and optimized under continuous flow conditions. After the optimization, the reaction steps were coupled in a semi-continuous flow system, since a solvent exchange had to be performed after the tosylation. However, the azidation and the reduction steps were compatible to be coupled in one flow system obtaining 6-monoamino-6-monodeoxy-β-cyclodextrin in a high yield. Our flow method developed is safer and faster than the batch approaches.

Mono-6-Substituted Cyclodextrins-Synthesis and Applications

Cyclodextrins are well known supramolecular hosts used in a wide range of applications. Monosubstitution of native cyclodextrins in the position C-6 of a glucose unit represents the simplest method how to achieve covalent binding of a well-defined host unit into the more complicated systems. These derivatives are relatively easy to prepare; that is why the number of publications describing their preparations exceeds 1400, and the reported synthetic methods are often very similar. Nevertheless, it might be very demanding to decide which of the published methods is the best one for the intended purpose. In the review, we aim to present only the most useful and well-described methods for preparing different types of mono-6-substituted derivatives. We also discuss the common problems encountered during their syntheses and suggest their optimal solutions.

Room-temperature blue-light-emitting liquid crystalline materials based on phenanthroimidazole-substituted carbazole derivatives

We report disc-shaped materials with the A–Π–D molecular architecture based on the phenanthroimidazole-linked carbazole group as blue-light-emitting materials with room-temperature liquid crystalline properties.

Columnar self-assembly, electrochemical and luminescence properties of basket-shaped liquid crystalline derivatives of Schiff-base-moulded p-tert-butyl-calix[4]arene

A new family of blue-light emitting supramolecular basket-shaped liquid crystalline compounds based on p-tert-butyl-calix[4]arene core to form self-assembly and columnar hexagonal phase.

New Class of Supramolecular Bowl-Shaped Columnar Mesogens Derived from Thiacalix[4]arene Exhibiting Gelation and Organic Light-Emitting Diodes Applications

A new class of blue light-emitting bowl-shaped mesogens with the thiacalix[4]arene core appended with 1,3,4-thiadiazole derivatives having peripheral alkoxy side chains have been synthesized and well characterized. The liquid crystalline behavior of present synthesized derivatives was examined by optical polarizing microscopy, differential scanning calorimetry, and X-ray diffraction studies. It was observed that these thiacalix[4]arene derivatives were capable of stabilizing the observed Col_h phase with a higher temperature range. The cone-shaped thiacalix[4]arene-based liquid crystals with peripheral alkoxy side chains able to pack into the columns with enriched intermolecular interactions and thermal behavior. All derivatives showed blue luminescence in solution, solid thin-film, and gelation state. The hexagonal columnar phase and emissive nature of thiadiazole-based thiacalixarene compounds having xerogel behavior make them favorable in the application of emissive electronic display devices. The electrochemical properties of these thiacalixarene-based compounds demonstrate the effect of alkyl side chain on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels and also exhibited lower electron band gaps. The electroluminescence behavior of the compound 10c was examined as emissive layers in the fabrication of organic light-emitting diodes.

A new class of supramolecular liquid crystals derived from azo calix[4]arene functionalized 1,3,4-thiadiazole derivatives

A new class of bowl-shaped supramolecular liquid crystals (LCs) is described derived from calix[4]arene substituted with 1,3,4-thiadiazole derivatives, inbuilt with Schiff base and ester on the lower rim and with an azo group on the upper rim with an alkyl side chain (–OC₃H₇, –OC₈H₁₇).

Columnar self-assembly, gelation and electrochemical behavior of cone-shaped luminescent supramolecular calix[4]arene LCs based on oxadiazole and thiadiazole derivatives

A new class of blue light-emitting supramolecular liquid crystalline cone or bowl-shaped compounds were synthesized from substituted 1,3,4-oxadiazoles and 1,3,4-thiadiazoles with calix[4]arene derivatives.

Bowl-shaped fluorescent liquid crystals derived from 4-tert butyl calix[4]arene and trans cinnamic acid derivatives

A new family of bowl-shaped molecules with a calix[4]arene rigid core appended by four-side and two-side substitution with trans 4-n-alkoxy cinnamic acid has been synthesized and well characterized.

Columnar self-assembly of bowl shaped fluorescent liquid crystals based on calix[4]arene with Schiff base units

A new family of bowl-shaped molecules with a calix[4]arene rigid core and appended on four-sides, that display a wide range of hexagonal columnar phases, has been synthesised and well characterized.

A Family of Amphiphilic Cyclodextrin Liquid Crystals Governed by Dipole-Dipole Interactions

A novel family of amphiphilic cyclodextrin(CD)-based liquid crystals that bear O-acetylated oligoethylene glycol chains at the secondary face is reported. Unlike most of the previously reported liquid crystals (LC) based on chemically modified CDs, which depend on H-bonding as the primary intermolecular forces, the present CD derivatives self-assemble into highly ordered smectic liquid crystal phases via the weaker dipole-dipole intermolecular interactions. The obtained materials are found to display much improved properties such as improved thermostability, reduced clearing temperatures, and better fluidity. The present work opens up new possibilities to design CD-based LC materials.

Liquid-crystalline mesogens based on cyclo[6]aramides: distinctive phase transitions in response to macrocyclic host-guest interactions

Producing macrocyclic mesogens that are responsive to guest encapsulation presents a significant challenge. Cyclo[6]aramides, a type of macrocycle with a hydrogen-bond-constrained backbone, exhibit thermotropic lamellar, discotic nematic, hexagonal, and rectangular columnar mesophases over a considerably wide temperature range, including at room temperature. Additionally, cyclo[6]aramides show unusual mesophase transitions from lamellar to hexagonal columnar phase mediated by macrocyclic host-guest (H-G) interactions between the macrocycles and alkylammonium salts. The phase transition, triggered by an organic guest engaging in H-G interactions with a macrocyclic cavity, provides a novel strategy for manipulating the properties of liquid-crystalline materials. The crystal structure of a homologous cyclo[6]aramide reveals a disk-shaped, near-planar molecular backbone that facilitates intermolecular π-π stacking and leads to columnar assembly.

Synthesis, Photo-physical and Electrochemical Properties of Dendrimers with (S)-BINOL Core and Benzothiazole Surface Unit

Chiral dendritic architectures with benzothiazole as surface group, 1,2,3-triazole as a bridging unit, and (S)-BINOL (1,1-bi-2-naphthol) as a core unit were synthesised in good yields via a convergent synthetic strategy. The chiroptical properties of the dendrimers revealed that the specific rotation increased in the order of dendrimers 4 > 3 > 2 > 1. All the dendrimers showed excellent optical and electrochemical response, and hence would find application in dye-sensitised solar cells.