Visualizing the helical stacking of octahedral metallomesogens with a chiral core

Magnetic Supramolecular Spherical Arrays: Direct Formation of Micellar Cubic Mesophase by Lanthanide Metallomesogens with 7-Coordination Geometry

Here, an unprecedented phenomenon in which 7-coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H2O molecules, form micellar cubic mesophases at room temperature, creating body-centered cubic (BCC)-type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self-assembling behavior of 6-coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7-coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases.

Aquatic Functional Liquid Crystals: Design, Functionalization, and Molecular Simulation

Aquatic functional liquid crystals, which are ordered molecular assemblies that work in water environment, are described in this review. Aquatic functional liquid crystals are liquid-crystalline (LC) materials interacting water molecules or aquatic environment. They include aquatic lyotropic liquid crystals and LC based materials that have aquatic interfaces, for example, nanoporous water treatment membranes that are solids preserving LC order. They can remove ions and viruses with nano- and subnano-porous structures. Columnar, smectic, bicontinuous LC structures are used for fabrication of these 1D, 2D, 3D materials. Design and functionalization of aquatic LC sensors based on aqueous/LC interfaces are also described. The ordering transitions of liquid crystals induced by molecular recognition at the aqueous interfaces provide distinct optical responses. Molecular orientation and dynamic behavior of these aquatic functional LC materials are studied by molecular dynamics simulations. The molecular interactions of LC materials and water are key of these investigations. New insights into aquatic functional LC materials contribute to the fields of environment, healthcare, and biotechnology.

C- and S-Shaped Perylene Diimide Heterohelicenes: Modular Synthesis and Spiral-Stair-Like π-Stacking

A number of C- and S-shaped perylene diimide (PDI) heterohelicenes with high dipole moments were synthesized from simple perylene tetrabutylester (PTE). Taking advantage of the weak coordination ability of the sterically crowded peri ester groups in PTE, efficient Rh(III)-catalyzed 2,8- and 2,11-bisiodinations of the perylene core were realized. The 2,8- and 2,11-diiodinated PTEs and PDIs represent key synthons for further ortho-π-extensions. In contrast to most helical π-skeletons that feature loose molecular packings, enantiomerically pure C-shaped PDI azahelicenes adopt unique spiral-stair-like π-stacking superstructures.

Metal-Ion Specific Recognition with Amplified Transcription from Subnanometer to Submillimeter or Real-Time Domain by Self-Assembled Vanadyl Quartets

Vanadyl(V) complexes 1 and 2 bearing a nematic liquid crystal (LC) like a p-heptoxyphenyl group or a fluorous-tag p-nonafluoroheptoxyphenyl (NFH) group at the C5 position of the N-salicylidene template were designed and synthesized. Each complex was subjected to MVO₃-induced self-assembly to form metal-ion, encapsulated quartet clusters 3-M and 3'-M. The Na⁺ in cluster complex 3-Na or 3'-Na can be readily replaced by Rb⁺, Ag⁺, or Hg²⁺ in an aqueous layer to form cluster complexes by ion swapping at the H₂O/CDCl₃ bilayer interface. Selectivity profiles were examined with alkali-metal ions, Ag⁺, and Hg²⁺ through metal-ion competition experiments. The 3'-Na has an exclusive selectivity for Hg²⁺ in the presence of Zn²⁺ and Cd²⁺. Cluster complexes 3-M were utilized as chiral dopants to nematic LC materials. The effects of the encapsulated metal ions within the alkali family and Ag⁺ on Cano's line widths and helical pitch changes were viewed in wedge cells under a polarized microscope. Their correlations with the ionic radius were identified. The subnano information of the metal ions can thus be asymmetrically amplified to Cano's line spacings of the submilimeter domain. Conversely, the effects of the encapsulated alkali metal ions and Hg²⁺ in 3'-M on the interactions of their NFH tails toward fluorous silica gel (FSG) were performed via HPLC analyses. Their retention times became longer as the sizes of encapsulated, alkali metal ions increased. The increasing ion size from Na⁺ to Cs⁺ caused the four lower rim NFH tags of the cluster to be closer due to reduced cone angles. Their interactions among NFH tail groups on FSG became larger, thus leading to distinctive separations with t_R from 7.36 to 10.27 min. The retention time difference between 3'-Na and 3'-Hg on HPLC was ∼3.6 min, resulting in discernible separation. The individual ion size differences on the subnano scale can thus be amplified and unambiguously established in the real time domain.

Advanced Functional Luminescent Metallomesogens: The Key Role of the Metal Center

The use of liquid crystals for the fabrication of displays incorporated in technological devices (TVs, calculators, screens of eBook's, tablets, watches) demonstrates the relevance that these materials have had in our way of living. However, society evolves, and improved devices are looked for as we create a more efficient and safe technology. In this context, metallomesogens can behave as multifunctional materials because they can combine the fluidic state of the mesophases with properties such as photo and electroluminescence, which offers new exciting possibilities in the field of optoelectronics, energy, environment, and even biomedicine. Herein, it has been established the role of the molecular geometry induced by the metal center in metallomesogens to achieve the self-assembly required in the liquid-crystalline mesophase. Likewise, the effect of the coordination environment in metallomesogens has been further analyzed because of its importance to induce mesomorphism. The structural analysis has been combined with an in-depth discussion of the properties of these materials, including their current and potential future applications. This review will provide a solid background to stimulate the development of novel and attractive metallomesogens that allow designing improved optoelectronic and microelectronic components. Additionally, nanoscience and nanotechnology could be used as a tool to approach the design of nanosystems based on luminescent metallomesogens for use in bioimaging or drug delivery.

Molecular insights on confined water in the nanochannels of self-assembled ionic liquid crystal

Self-assembled ionic liquid crystals can transport water and ions via the periodic nanochannels, and these materials are promising candidates as water treatment membranes. Molecular insights on the water transport process are, however, less investigated because of computational difficulties of ionic soft matters and the self-assembly. Here we report specific behavior of water molecules in the nanochannels by using the self-consistent modeling combining density functional theory and molecular dynamics and the large-scale molecular dynamics calculation. The simulations clearly provide the one-dimensional (1D) and 3D-interconnected nanochannels of self-assembled columnar and bicontinuous structures, respectively, with the precise mesoscale order observed by x-ray diffraction measurement. Water molecules are then confined inside the nanochannels with the formation of hydrogen bonding network. The quantitative analyses of free energetics and anisotropic diffusivity reveal that, the mesoscale geometry of 1D nanodomain profits the nature of water transport via advantages of dissolution and diffusion mechanisms inside the ionic nanochannels.