Novel bolaamphiphiles, consisting of a biphenyl rigid core, polar 2,3-dihydroxypropoxy groups at each terminal end, and an additional long alkyl chain in a lateral position have been synthesized. The structures of these ternary block molecules were systematically changed by variation of the length and position of the alkyl chain, by introduction of additional spacer units between one of the 2,3-dihydroxypropyl groups and the rigid core, and by replacement of one of the 2,3-dihydroxypropoxy groups by a single hydroxy group. The influence of these structural variations on the liquid crystalline properties of these new materials was investigated by polarized-light microscopy, differential scanning calorimetry, and X-ray diffraction. These investigation have shown that, by elongation of the lateral chain, a transition from a smectic monolayer structure (SmA 1 ) via a strongly distorted layer structure (SmA + ), a centered rectangular columnar phase (Col r /c2mm) and a noncentered rectangular columnar phase (Col r /p2gg) to a hexagonal columnar phase (Col h /p6mm) takes place. Elongation of the bolaamphiphilic core leads to the loss of the columnar phases, which are replaced by smectic phases, whereas reduction of its length favors the hexagonal columnar phase. This phase sequence is explained as a result of the microsegregation of the lateral alkyl chains from the rigid aromatic cores. The segregated alkyl chains are organized in columns that interrupt the smectic layers. The hydrogen bonding keep the bolaamphiphilic cores fixed end to end, so that they form networks of cylinders around the lipophilic columns. The space required by the alkyl chains with respect to the length of the bolaamphiphilic cores is restricted and largely determines the geometry of the cylinders, which leads to the observed phase sequence. The obtained mesophase morphologies, built up by three distinct sets of subspaces, are related to morphologies of some ternary block copolymers. Furthermore, the investigated compounds represent a novel class of materials, capable of forming supramolecular columnar mesophases.

Gradual clogging of the apertures of nanostencils used as miniature shadow masks in metal evaporations can be reduced by coating the stencil with self-assembled monolayers (SAM). This is quantified by the dimensions (height and volume) of gold features obtained by nanostencil evaporation as measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). An increase in material deposition through the apertures by more than 100% can be achieved with SAM-coated stencils, which increases their lifetime.

Rigid bolaamphiphiles with lateral alkyl chains such as 1 form columnar mesophases of a novel type based on microsegregation of the three incompatible parts of the molecules (shown schematically).

Rodlike amphiphilic molecules that contain exclusively aromatic building-blocks and no flexible alkyl chains have been synthesized and their mesomorphic properties investigated. These novel compounds bear diol head groups of different size (2,3-dihydroxypropyloxy or 5,6-dihydroxy-3-oxahexyloxy groups) at one end of a biphenyl unit, various aromatic segments (benzyloxy, 4-, 3-, or 2-methylbenzyloxy, phenoxy groups) at the other, and additional methyl substituents in different positions. They were synthesized by using Suzuki cross-coupling reactions as the key steps. Their thermotropic mesomorphism was investigated by means of polarized light optical microscopy, differential scanning calorimetry, and, for enantiotropic phases, by X-ray scattering. The liquid crystallinity of this class of compounds is influenced by protic solvents, such as water and glycerol. Dependent on the temperature and the solvent content, different SA phases were found. Several mesophases resulting from the frustration of these layer structures (e.g., different columnar phases, optical isotropic mesophases, and nematic phases) were also present. The smectic phases have different degrees of intercalation (SAd, SA2). The columnar phases are supposed to be ribbon structures that result from the collapse of the smectic layers. They occur in some pure compounds or they are induced upon the addition of protic solvents. The particular phase sequences of the different compounds depend mainly on the position of the methyl substituents at the biphenyl cores and are largely determined by the degree of intercalation of the aromatic cores.

Removal of the liquid from a glycoluril-based gel produces a macroporous solid (a xerogel) comprised of closely packed fibers that assemble into highly convoluted sheets.

Nanostencils (shadow masks with submicrometer apertures in a thin silicon nitride membrane) are promising tools for the facile one‐step generation of nanopatterns of various materials by physical vapor deposition. Evaporation through a shadow mask is accompanied by gradual clogging of the apertures due to adhesion of evaporated material. In order to reduce this effect, nanostencils were coated with alkyl and perfluoroalkyl self‐assembled monolayers (SAMs). The formation and properties of SAMs on planar silicon nitride substrates were studied by contact angle goniometry, X‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The SAMs are stable under evaporation of gold at various angles. SAM‐coated nanostencils showed considerably less adhesion of gold compared to bare SixNy stencils.

Novel amphiphilic 4,4′-disubstituted biphenyl derivatives incorporating a hydrophilic 5,6-dihydroxy-3oxahexyloxy group and a lipophilic chain have been synthesized by Pd-catalyzed cross-coupling reactions of phenyl boronic acids with 4-(5,6-dihydroxy-3-oxahexyloxy)bromobenzenes. The thermotropic and lyotropic mesomorphic behavior of these compounds were investigated by polarizing microscopy, by differential scanning calorimetry, and by means of X-ray diffraction. Thereby the influence of the length of the alkyl chain, the type of connecting unit between alkyl-chain and the rigid core (O vs CH 2 ), and the influence of lateral substituents and of the molecular chirality on the mesomorphic properties were investigated. All compounds have smectic A-phases as the high-temperature mesophases. Additionally, columnar phases were found for the long chain 4′-alkoxy-4-(5,6-dihydroxy-3-oxahexyloxy)biphenyls 2c-f without lateral substituent and for the 4-(5,6-dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3′-methylbiphenyl 10. All other laterally substituted biphenyl derivatives 9 and 11-15 and the 4′-alkyl substituted compound 8 display only smectic phases. The influence of protic solvents (formamide and ethylene glycol) on the liquid crystalline properties was studied. The columnar mesophases and S C -phases are destabilized by addition of protic solvents whereas the S Aphases are stabilized. Furthermore, binary mixtures of the amphiphilic biphenyl derivatives with each other have been investigated. Complete miscibility was found for the S A -phases and the columnar phases of the compounds 2c-f. However the columnar phases of the nonsubstituted compounds 2c-f and the 3′-methyl substituted derivative 10 do not have an uninterrupted miscibility. Cubic phases (Pn3m or Pn3) and additional columnar phases were induced in the contact regions. Thus, the same diversity of different kinds of mesophases as in lyotropic systems and in the thermotropic phase sequence of polycatenar compounds is found. It is proposed that the cubic and columnar mesophases of these rodlike molecules result from the collapse of the smectic layer structures into ribbons.

Glycoluril, a bisurea compound known for 125 years, has during the past two decades established an impressive career as building block for supramolecular chemistry. The recent literature shows that glycoluril derivatives have a strong potential for applications in the materials sector, ranging from nanoporous materials via molecular switches, tailor‐made polymers, synthetic receptors, liquid crystals, and molecular capsules to supramolecular gels.