The Role of the 1,2,3-Triazolyl Heterocycle in the Helical Columnar Assembly and Electric Field Response.

Here, we have proven the role of the 1,2,3-triazolyl group in the helical assembly and electric field (E-field) response upon comparing liquid crystal analogs and based on 1,2,3-triazolyl and 1,3,4-oxadiazolyl linkers, respectively. An ordered helical column was only observed in , driven by the hydrogen-bonding interactions between the adjacent triazolyl nitrogen and hydrogen atoms. X-ray diffraction and energy simulations indicate that the helical column is a 11 helix and the helical axis does not coincide with the center of the molecular long axis.

Ferroelectrically Switchable Axial Polarization in Columnar Liquid Crystalline Phases.

Recently, ferroelectrically switchable columnar LCs have drawn a great deal of attention for their generation of rich polarization domains. Because of their unique dielectric and self-assembly properties, they are considered to be a promising material for the design of sensors and ultra-high memory devices. Herein, ferroelectrically switchable LCs by using ester, amide, and 1,2,3-triazole groups are reviewed.

Development of Gallic Acid-Modified Hydrogels Using Interpenetrating Chitosan Network and Evaluation of Their Antioxidant Activity.

In this work, antioxidant hydrogels were prepared by the construction of an interpenetrating chitosan network and functionalization with gallic acid. The poly(2-hydroxyethyl methacrylate) p(HEMA)-based hydrogels were first synthesized and subsequently surface-modified with an interpenetrating polymer network (IPN) structure prepared with methacrylamide chitosan via free radical polymerization. The resulting chitosan-IPN hydrogels were surface-functionalized with gallic acid through an amide coupling reaction, which afforded the antioxidant hydrogels.

Sequential phase transformation of propeller-like C3-symmetric liquid crystals from a helical to ordered to disordered hexagonal columnar structure.

In this paper, we report thermally induced intercolumnar phase transitions of C3-symmetric liquid crystals (LCs) bearing a triazole-based propeller-like aromatic mesogen. Since the constituting aromatic rings are conjugated through rotatable single bonds, the mesogenic shape is tuneable depending on the degree of conformational motion. Molecule 1 with ninefold octyl peripheries shows a hexagonal columnar liquid crystalline phase transition from ordered mesogenic stacking to disordered mesogenic stacking upon heating.

Micellar and vesicular nanoassemblies of triazole-based amphiphilic probes triggered by mercury(II) ions in a 100% aqueous medium.

ABA-type amphiphiles bearing a triazole-based aromatic block were easily synthesized using click chemistry, which act as fluorescent turn-off Hg(2+)-chemoprobes in an aqueous solution. Interestingly, the metal-binding process of amphiphiles induced nanoassemblies even below the CMCs, and the binding stoichiometry affected the morphologies of the resultant nanostructures.

Monoclinic to two-dimensional hexagonal transformation in hexacatenar molecules with a 1,2,3-triazole-based conjugated rod: morphology-dependent thermochromic behavior.

Novel hexacatenar molecules based on a 1,2,3-triazole-extended aromatic rod self-assemble into crystalline monoclinic and liquid crystalline hexagonal columnar structures depending on temperature. The phase transition may involve a conformational change from an anisotropic transoid to a half-disk cisoid conformer upon melting. In a hexacatenar molecule with sixfold octyl chains, the crystal-to-LC transition accompanies a photoluminescence color change from sky blue to dark blue, which is attributed to the formation of higher-order aggregates in the crystalline state.

An unusual stacking transformation in liquid-crystalline columnar assemblies of clicked molecular propellers with tunable light emissions.

The columnar liquid-crystalline (LC) and fluorescence properties of three-dimensional molecular propellers based on tetraphenylethylene is reported. X-ray scattering studies reveal an unusual transition from a rectangular (Colrec ) to a hexagonal columnar (Colhex ) phase. In contrast to second-order intercolumnar transitions based on a common tilt mechanism, the transition is first order and involves an unprecedented zigzag stacking of aromatic propellers in the Colrec phase.

Smectic assemblies in C₃-symmetric hexa-alkylated liquid crystals: transformation from smectogen to discogen via hydrogen bonding.

In this paper, we report a C3-symmetric liquid crystal (LC) with sixfold alkyl peripheries exhibiting an unusual smectic E-like organization in the LC state. Based on conformational considerations, the smectic assembly is attributed to the formation of an endo-type Y conformer of asymmetric triazolyl and benzylic groups that cannot be accessed in other C3-symmetric molecules exclusively showing columnar assemblies. The Y conformers form a two-dimensional oblique lattice in the aromatic layers of the ordered smectic phase.

Supramolecular transformation from ordered columnar to disordered columnar to tetragonal micellar structures in clicked dodeca-alkylated discotic triphenylene liquid crystals.

We prepared three discotic liquid crystals (DLCs) based on a triphenylene (TP) disc functionalized with twelve alkyl peripheries. The synthesis of the discogens was performed by a click reaction using Cu(OAc)2 as the catalyst, with six triazolyl groups connecting the TP core with twelve alkyl chains. According to thermal data from differential scanning calorimetry (DSC), discogen , which has the shortest hexyl peripheries, exhibited two LC phases, and and , with decyl and tetradecyl peripheries, respectively, displayed three LC phases as a function of the temperature.

Organic-inorganic vesicular hybrids driven by assembly of dendritic amphiphiles: site-selective encapsulation of nanoparticles.

The amphiphilic block codendrimer self-assembled into supramolecular vesicles with a bilayer membrane in both hydrophilic and hydrophobic solvents. Surface-modified quantum dots (QDs) were successfully entrapped within the wall of vesicles through a simple self-assembly process without any structural disruption.

Functionality- and Size-Dependent Target-Differentiation of Nanoporous Carboxylated Polystyrenes in Polar Protic Solvents.

In this study, we investigated the functionality- and size-dependent differentiation capability of bulk nanoporous polystyrene (PS) materials in aqueous environments. A three-arm star block copolymer (consisting of dibranched PS and linear polylactide (PLA) blocks) was employed to prepare PS nanochannels with the average pore diameter of 14.2 nm.

Non-tortuous ionic transport in robust micellar liquid crystalline phases with cubic symmetry.

A micellar cubic LC phase consisting of a hydrophilic matrix exhibited enhanced ionic transport and mechanical properties without macroscopic orientation, which are attributed to the non-tortuous ionic transport and highly symmetric cubic lattice, respectively.

Thickness-dependent morphological behavior of dendritic (PS)2-b-PLA copolymer thin films on a SiO2 substrate.

In contrast to the known perpendicular ordering of conventional PS-b-PLA thin films, branched (PS)(2)-b-PLA thin films showed two different parallel orientations whose locations are strongly dependent upon film thickness.

An extraordinary cylinder-to-cylinder transition in the aqueous assemblies of fluorescently labeled rod-coil amphiphiles.

We report an unprecedented cylinder-to-cylinder transformation in the self-assemblies of pyrene-labeled rod-coil molecules in water. The extraordinary morphological transformation can be monitored by a fluorescence variation from exciplex to excimer emissions, suggesting the rod-packing transition from antiparallel to interdigitated arrangements as a function of PEO coil length.

Self-assembling behavior of amphiphilic dendron coils in the bulk crystalline and liquid crystalline states.

We prepared a series of amphiphilic dendron coils (1-3) containing aliphatic polyether dendrons with octadecyl peripheries and a poly(ethylene oxide) (PEO) coil (DP = 44). The molecular design in this study is focused on the variation of dendron generation (from first to third) with a fixed linear coil, upon which the thermal and self-assembling behavior of the dendron coils was investigated in the bulk. All the dendron coils exhibit two crystalline phases designated as k1 (both crystalline octadecyl chains and PEO) and k2 states (crystalline octadecyl chains and molten PEO).

Selectively chemodosimetric detection of Hg(II) in aqueous media.

A new series of benzoylthiourea derivatives of 1, 3, and 5 were prepared, and their chemodosimetric behaviors toward metal cations were investigated in aqueous media at room temperature. Among various metal cations tested, exclusively Hg2+ ion responses to irreversible color changes of receptors, along with distinctive blue shifts in UV/vis spectra. The receptors can be applicable for the monitoring of Hg2+ ion in aqueous solution with a pH span 4-9.

Observation of an unprecedented body centered cubic micellar mesophase from rod-coil molecules.

We have demonstrated that rod-coil molecules based on a tetra-p-phenylene rod and a poly(propylene oxide) coil self-assemble into an unprecedented body centered cubic micellar structure in the melt, through detailed morphological analysis by X-ray scattering and transmission electron microscopy experiments.

Generation dependent mesophase behavior in extended amphiphilic dendrons in the shape of macromolecular dumbbells.

Small angle X-ray scattering studies of 2nd and 3rd generation based extended amphiphilic dendrons in the shape of macromolecular dumbbells with identical hydrophilic volume fractions suggest 2-D hexagonal columnar and Pm3n micellar cubic mesophases, respectively, elucidating the role of shape induced interface curvature in mesophase formation.

Nanohybrids from liquid crystalline extended amphiphilic dendrimers.

A novel extended amphiphilic dendrimer with linear poly(ethylene oxide) (PEO) attached to a PEO-like dendritic core as hydrophilic fraction and eight docosyl chain branches as hydrophobic fraction has been prepared for the use as structure-directing agent for silica-type materials. The extended dendrimer exhibits a hexagonal columnar liquid crystalline phase in the melt. Organically modified inorganic precursors and the extended dendrimer co-assemble into nanostructured hybrids.

Self-assembly of molecular dumbbells into organized bundles with tunable size.

Dumbbell-shaped molecules consisting of three biphenyls connected through vinyl linkages as a conjugated rod segment and aliphatic polyether dendritic wedges with different cross-sections (i.e., dibranch (1), tetrabranch (2) and hexabranch (3)) were synthesized and characterized.

Cubic and Columnar Supramolecular Architectures of Rod-Coil Molecules in the Melt State.

The liquid crystalline behavior of compounds 1 (n = 7, 12, 15) differs significantly from that exhibited for conventional rodlike molecules. They organize into layered smectic, bicontinuous cubic or hexagonal columnar mesophases depending on the temperature or the volume fraction of coil segments.