Solution Processable Se-annulated Swallow Tail Perylene Bisimide Exhibiting Room Temperature Columnar Phase and Efficient Ambipolar Charge Carrier Mobility.

This study presents a selenium-annulated perylene bisimide (PBI-SeST) stabilizing room temperature columnar hexagonal phase with exceptionally low clearing temperature. The synthesis of this Se-annulated PBI (PBI-SeST) was accomplished using the reductive Cadogan cyclization method, with the introduction of swallow tails to reduce the clearing temperature and improve solubility. In addition, the charge carrier mobility of the Se-bay annulated PBI is assessed by space charge limited current (SCLC) technique and juxtaposed with PBI as well as nitrogen and sulphur-bay-annulated PBIs.

Novel class of ambipolar columnar liquid crystals based on cyclic dipeptide and isatin hybrids.

A new class of cyclic dipeptide-isatin hybrids was synthesized using 2,5-diketopiperazine and various isatin derivatives bearing flexible chains and extended aromatic rings in a double Knoevenagel condensation process. These new series demonstrate high solubility and good thermal stability with decomposition temperatures exceeding 370 °C, especially the molecular design with efficient space-filling (CI5 and CI6) stabilized columnar liquid crystalline phase. The hole and electron carrier mobility of the CI5 compound, measured using the space charge limited current (SCLC) technique, were found to be 9.

Tuning the Liquid Crystallinity and Electroluminescence via Sulfonation of S-Annulated Perylene Tetraester.

This study presents a comparative analysis of S-annulated perylene tetraester (PTE-S) and its sulfone (PTE-SO) analogue. This sulfone modification reduced melting point and stabilized a room temperature columnar rectangular (Col) phase in contrast to its parent PTE-S which showed a crystalline behaviour at room temperature. This molecular design also leads to red-shifted absorbance and emission in comparison to PTE-S, along with a tuning of photoluminescence from sky blue to green, achieving an impressive quantum yield of 85 %.

Visible light mediated synthesis of 1,3-diarylated imidazo[1,5-]pyridines oxidative amination of C-H catalyzed by graphitic carbon nitride.

Graphitic carbon nitride (g-CN) as a novel heterogeneous catalyst is employed for the visible light-mediated synthesis of the imidazo[1,5-]pyridines the oxidative amination of C-H bond at room temperature without the need for any additional solvent. Extensive characterization of the catalyst was performed using techniques such as FT-IR, PXRD, TGA, SEM and EDX analysis. The optimized conditions enabled the successful and expeditious conversion of a wide range of substrates to imidazo[1,5-]pyridines in good yields; a notable advantage of this catalyst being recyclability, as it can be reused for up to five cycles without significant loss of activity.

Highly Soluble Ambipolar anti-Perylene-3,4 : 9,10-bis(benzimidazole)s Stabilize a Room-Temperature Columnar Hexagonal Phase.

A new series of highly soluble perylene anti-bis(4,5-dialkoxybenzimidazole)s bearing branched flexible chains stabilizing room temperature columnar hexagonal phase and with balanced ambipolar charge carrier mobility is reported for the first time. Only the anti isomer was successfully separated and characterized. These compounds have a high extinction coefficient, small optical band gap and wide absorption range, thus making them a promising class of ambipolar organic semiconductors capable of self-organizing.

First example of ambipolar naphthalene diimide exhibiting a room temperature columnar phase.

A self-assembled ambipolar organic semiconductor based on naphthalene diimide with low clearing temperature, solution processability, and high molar extinction coefficient, exhibiting a room temperature columnar hexagonal liquid crystalline phase is reported.

Calixarene Functionalized Supramolecular Liquid Crystals and Their Diverse Applications.

Liquid crystals are considered to be the fourth state of matter with an intermediate order and fluidity in comparison to solids and liquids. Calixarenes are among one of the most versatile families of building blocks for supramolecular chemistry due to their unique vaselike structure that can be chemically engineered to have different shapes and sizes. During the last few decades, calixarenes have drawn much attention in the field of supramolecular chemistry due to their diverse applications in the fields of ion and molecular recognition, ion-selective electrodes for catalysis, drug delivery, gelation, organic electronics and sensors, etc.

Structure-property relationships of quinoxaline-based liquid crystals.

Quinoxaline derivatives with different molecular structures stabilizing liquid crystalline self-assembly are discussed in this review. This class of molecules can be systematically modified with careful molecular engineering to achieve different molecular shapes, directing them to self-assemble into various types of mesophases. The structure-property relationships of such molecules and the resultant self-assembled functional structures are of utmost importance in organic electronic devices and related applications.

Room-Temperature, Deep-Red/NIR-Emissive, -Symmetric (n,π-conjugated) Columnar Liquid Crystals: -Tris(keto-hydrazone)s.

The first examples of deep-red/near-infrared (NIR) photoluminescent, (n,π-conjugated) discotics, namely, -tris(keto-hydrazone)s, which are the tautomers of tris(azo-enol)s, have been synthesized via a facile one-step triple azo-coupling and characterized. The n,π-resonance-assisted intramolecular H-bonding, rendering planarity and shape persistence to the central core, facilitates their self-assembly into either a hexagonal columnar (Col) phase (6 lattice) or a columnar rectangular (Col) phase (2 lattice), over an extended thermal range including room temperature, fluorescing in the deep-red/NIR-I region. The low band gap with deep-red/NIR emission makes them ideal candidates for NIR-organic light-emitting diodes (OLEDs) and bioimaging.

Functional Ionic Liquid Crystals.

Ionic liquid crystals have emerged as a new class of functional soft materials in the last two decades, and they exhibit synergistic characteristics of ionic liquids and liquid crystals such as macroscopic orientability, miscibility with various species, phase stability, nanostructural tunability, and polar nanochannel formation. Owing to these characteristics, the structures, properties, and functions of ionic liquid crystals have been a hot topic in materials chemistry, finding various applications including host frameworks for guest binding, separation membranes, ion-/proton-conducting membranes, reaction media, and optoelectronic materials. Although several excellent review articles of ionic liquid crystals have been published recently, they mainly focused on the fundamental aspects, structures, and specific properties of ionic liquid crystals, while these applications of ionic liquid crystals have not yet been discussed at one time.

Helical supramolecular polymers with rationally designed binding sites for chiral guest recognition.

Since various helical supramolecular polymers became available, their application to molecular chirality recognition have been anticipated but not extensively studied. So far, only a few examples of chiral reactions have been reported, but none for chiral separation. Here, we report the application of a helical supramolecular polymer to the enantio-separation of chiral guest molecules.

Perylene-Based Liquid Crystals as Materials for Organic Electronics Applications.

Columnar phases formed by the stacking of disclike molecules with an intimate π-π overlap forms a 1D pathway for the anisotropic charge migration along the columns. Columnar phases have great potential in organic electronic devices to be utilized as active semiconducting layers in comparison to organic single crystals or amorphous polymers in terms of processability, ease of handling, and high charge carrier mobility. Intelligent molecular engineering of perylene and its derivatives provided access to tune the physical properties and self-assembly behavior.

Effect of Atomic-Scale Differences on the Self-Assembly of Thiophene-based Polycatenars in Liquid Crystalline and Organogel States.

Two series of polycatenars are reported that contain a central thiophene moiety connected to two substituted oxadiazole or thiadiazole units. The number, position, and length of the peripheral chains connected to these molecules were varied. The oxadiazole-based polycatenars exhibited columnar phases with rectangular and hexagonal or oblique symmetry, whereas the thiadiazole-based polycatenars exhibited columnar phases with rectangular and/or hexagonal symmetry.

Liquid-Crystalline Star-Shaped Supergelator Exhibiting Aggregation-Induced Blue Light Emission.

A family of closely related star-shaped stilbene-based molecules containing an amide linkage are synthesized, and their self-assembly in liquid-crystalline and gel states was investigated. The number and position of the peripheral alkyl tails were systematically varied to understand the structure-property relation. Interestingly, one of the molecules with seven peripheral chains was bimesomorphic, exhibiting columnar hexagonal and columnar rectangular phases, whereas the rest of them stabilized the room-temperature columnar hexagonal phase.

Bay-Annulated Perylene Tetraesters: A New Class of Discotic Liquid Crystals.

Selenium-annulated perylene tetraesters that stabilize the hexagonal columnar phase have been synthesized and characterized, and their thermal and photophysical behavior has been determined. The mesophase range decreased with an increase in chain length. A comparative account of the structure-property relationships of this series of compounds with respect to parent perylene tetraesters, N- and S-annulated perylene tetraesters, in terms of their thermal, photophysical and electrochemical behavior is provided.

Perylo[1,12-b,c,d] Thiophene Tetraesters: A New Class of Luminescent Columnar Liquid Crystals.

Perylo[1,12-b,c,d] thiophene tetraesters exhibiting wide-range hexagonal columnar phase have been synthesized. These compounds also exhibit good homeotropic alignment in the liquid-crystalline phase which is very important for the device fabrication. These compounds showed sky-blue luminescence in solution under the long-wavelength UV light.