We present a new local density functional, called M06-L, for main-group and transition element thermochemistry, thermochemical kinetics, and noncovalent interactions. The functional is designed to capture the main dependence of the exchange-correlation energy on local spin density, spin density gradient, and spin kinetic energy density, and it is parametrized to satisfy the uniform-electron-gas limit and to have good performance for both main-group chemistry and transition metal chemistry. The M06-L functional and 14 other functionals have been comparatively assessed against 22 energetic databases. Among the tested functionals, which include the popular B3LYP, BLYP, and BP86 functionals as well as our previous M05 functional, the M06-L functional gives the best overall performance for a combination of main-group thermochemistry, thermochemical kinetics, and organometallic, inorganometallic, biological, and noncovalent interactions. It also does very well for predicting geometries and vibrational frequencies. Because of the computational advantages of local functionals, the present functional should be very useful for many applications in chemistry, especially for simulations on moderate-sized and large systems and when long time scales must be addressed. © 2006 American Institute of Physics. DOI: 10.1063/1.2370993

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A new local density functional for main-group thermochemistry, transition metal bonding, thermochemical kinetics, and noncovalent interactions.

About Supramolecular Assemblies of π-Conjugated Systems

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

In recent years there has been immense interest in studying gels derived from low molecular mass gelators (supramolecular, or simply molecular gels). The motivation for this is not only to understand the fundamental aggregate structures in the gels at different length scales, but also to explore their potential for futuristic technological applications. Gels have been made sensitive to external stimuli like light and chemical entities by incorporating a spectroscopically active or a receptor unit as part of the gelator molecule. This makes them suitable for applications such as sensing and actuating. The diversity of gel structural architectures has allowed them to be utilized as templates to prepare novel inorganic superstructures for possible applications in catalysis and separation. Gels derived from liquid crystals (anisotropy gels) that can act as dynamically functional materials have been prepared, for example, for (re-writable) information recording. Supramolecular gels can be important in controlled release applications, in oil recovery, for gelling cryogenic fuels etc. They can also serve as media for a range of applications. This tutorial review highlights some of the instructive work done by various groups to develop smart and functional gels, and covers a wide spectrum of scientific interest ranging from medicine to materials science.

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Supramolecular gels: Functions and uses

Functional π-Gelators and Their Applications

In the 21st century, soft materials will become more important as functional materials because of their dynamic nature. Although soft materials are not as highly durable as hard materials, such as metals, ceramics, and engineering plastics, they can respond well to stimuli and the environment. The introduction of order into soft materials induces new dynamic functions. Liquid crystals are ordered soft materials consisting of self-organized molecules and can potentially be used as new functional materials for electron, ion, or molecular transporting, sensory, catalytic, optical, and bio-active materials. For this functionalization, unconventional materials design is required. Herein, we describe new approaches to the functionalization of liquid crystals and show how the design of liquid crystals formed by supramolecular assembly and nano-segregation leads to the formation of a variety of new self-organized functional materials.

Functional liquid-crystalline assemblies: self-organized soft materials.

Dynamische weiche Materialien werden im 21. Jahrhundert an Bedeutung gewinnen. Zwar sind diese Funktionsmaterialien nicht so bestandig wie Metalle, Keramiken oder Plastik, dafur reagieren sie aber gut auf externe Reize. Geordnete weiche Materialien konnen dynamische Funktionen erfullen. Flussigkristalle aus selbstorganisierten Molekulen sind ein Beispiel hierfur: Sie eignen sich moglicherweise zum Elektronen-, Ionen- oder Stofftransport sowie als sensorisch, katalytisch, optisch oder biologisch aktive Materialien. Um diese Funktionen auszuschopfen, benotigt man unkonventionelle Materialentwurfe. Hier beschreiben wir aktuelle Ansatze zur Funktionalisierung von Flussigkristallen und zeigen, wie das Design von Flussigkristallen durch supramolekulare Aggregation und Nanophasentrennung zu einer Vielfalt selbstorganisierter Funktionsmaterialien fuhrt.

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

An ion-conductive mesogenic monomer with an imidazolium ionic moiety has been designed to obtain self-assembled materials forming ionic layers. Self-standing polymer films are prepared by in situ photopolymerization of the monomer that forms homeotropic monodomain on a normal glass substrate in the smectic A phase. Macroscopically oriented, layered nanostructures are formed in the film. The ionic conductivity parallel to the smectic layer has been measured for the oriented film. In the smectic A phase at 150 °C, the magnitude of conductivity is about 10 - 2 S cm - 1 .

Nanostructured ion‐conductive films: Layered assembly of a side‐chain liquid‐crystalline polymer with an imidazolium ionic moiety

Nematic liquid-crystalline (LC) physical gels suitable for light scattering electrooptical displays have been prepared from a nematic liquid crystal and a low molecular weight gelator containing an oligo(L-isoleucine) moiety. The number of amino acid moieties of the gelators has a great effect on the gelation ability and electrooptical behaviour of the LC gels. A gelator having three L-isoleucine moieties forms LC gels most efficiently. The use of the gelator leads to microphase separation where fibres with a diameter of ca. 30 nm finely disperse in liquid crystals. Such structures are suitable for the induction of high light scattering. The light scattering states are electrically switched to transparent states in liquid crystal cells. The contrast of light transmittance and driving voltages are improved by the tuning of the gelator concentrations. A gelator having two L-isoleucine moieties exhibits poor gelation
ability. A mono-amino acid gelator forms LC gels showing lower light scattering, although they are applicable to twisted nematic mode.

Kenji Kishimoto

Papers

Functional liquid-crystalline assemblies: self-organized soft materials.

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

Nanostructured ion‐conductive films: Layered assembly of a side‐chain liquid‐crystalline polymer with an imidazolium ionic moiety

Electrooptical properties of liquid-crystalline physical gels: a new oligo(amino acid) gelator for light scattering display materials