Pyrazolate “Golden” Rings: Trinuclear Complexes That Form Columnar Mesophases at Room Temperature

Barberá, Joaquín; Elduque, Anabel; Giménez, Raquel; Oro, Luis A.; Serrano, José Luís

doi:10.1002/anie.199628321

Cited by 95 publications

(55 citation statements)

References 12 publications

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“…This idea failed, but it was observed that geometrically analogous pyrazolate-bridged gold trimers shown in Figure 14 formed columnar mesophases at room temperature. [45] In similar complexes, Cano et al noted the presence of an intramolecular hydrogen bond between the cis-chloro and 3-substituted pyrazole ligands. [46] Perhaps this hydrogen bond helps to restrict the rotation about the Rh-pyrazole bond and therefore to maintain the observed stacking of the square-planar units in the solid state ( Figure 15).…”

Section: Pyrazole Complexes and Liquid Crystalsmentioning

confidence: 98%

Pyrazole Complexes and Supramolecular Chemistry

2009

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This Microreview deals with the supramolecular chemistry of pyrazole metal complexes, in particular, complexes of pyrazoles with a nonsubstituted N–H group, which are able to engage in hydrogen bonding. The most pertinent general features of pyrazoles, in comparison with other heterocycles that are also popular ligands, and some aspects of the supramolecular chemistry of free pyrazoles are also included. In addition to the general supramolecular chemistry of pyrazole complexes, sections of this Microreview are devoted to liquid crystals, self‐assembled species, and hosts for anions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Pyrazole Complexes and Liquid Crystalsmentioning

confidence: 98%

Pyrazole Complexes and Supramolecular Chemistry

2009

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“…Columnar hexagonal (Col h ) and columnar rectangular (Col r ) phases are the most common in case of discotic molecules. However, certain molecules that are not disk-shaped may also exhibit such columnar mesophases depending on their supramolecular arrangements [5][6][7][8]. They may be bow-like [9] or polycatenars [10,11], i.e., the compound consists of a rod-like or bent mesogenic core with multiple terminal alkyl chains.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of New Nondisk-Shaped Thermotropic Liquid Crystalline Compounds Showing a Rectangular Columnar Mesophase

Majumdar

Roy

et al. 2011

Molecular Crystals and Liquid Crystals

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Linear-and polycatenar-type compounds possessing a cabazole moiety as a head group, linked to the trialkoxy terminal tails via a linear aromatic chain have been designed and synthesized. These compounds exhibit a liquid crystalline rectangular columnar phase. The mesomorphic nature was determined by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) in combination with powder XRD.

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“…Typical examples of metallomesogens with high coordination number are the lanthanide-containing liquid crystals [8,21 -28]. The synthesis of mesomorphic metallacrowns [29,30], butterfly compounds [31], metallodendrimers [32] and polynuclear systems [33 -36] opened up the field for the construction of original structures able to contain a large number of metallic centres.…”

Section: Introductionmentioning

confidence: 99%

Trimetallic Nickel–Lanthanum and Nickel–Gadolinium Metallomesogens

Binnemans

Lodewyckx

2003

Supramolecular Chemistry

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Supramolecular chemistry is a rapidly growing branch of chemistry, each year attracting the interest of more and more scientists. Intense research in the field has led to many discoveries, and different principles have been demonstrated: selfassembly, recognition of cations, anions and neutral molecules, biomimetic systems, supramolecular crystal engineering, molecular machines and so on. However, very few supramolecular systems lead to (industrial) applications. Before supramolecular compounds can be transformed into competitive new materials, more efficient synthetic routes to selfassembling building blocks have to be developed. Compounds which are accessible only after multiple tedious synthesis steps will be too expensive for applications. I think that a major goal in supramolecular chemistry should be the development of easy and cheap methods for the synthesis of target compounds.The quest for new synthetic routes and of new materials is also of importance in the subfield of supramolecular chemistry I am working in: metal-containing liquid crystals (metallomesogens). This research field has been dominated by chemists, not by physicists. During the last two decades, many different classes of metallomesogens have been discovered. At present, only a limited number of metals have not yet been incorporated in liquid crystals: hafnium, tantalum, niobium, scandium, gallium and indium (not to mention the radioactive elements). It is to be expected that the methodology which leads to the development of metallomesogens with the lanthanides or zirconium as the central metal ion can also be successfully applied to the design of metallomesogens containing the above-mentioned metal ions. There is still a need to develop new types of ligands for metallomesogens, because many of the metallomesogens described in the literature have very high transition temperatures or are thermally unstable. In comparison with the classic liquid crystals, very little is known about the physical properties of metallomesogens. Workers in the field of metallomesogens should encourage physicists to look in more detail at the properties of metal-containing liquid crystals. Because of the presence of a (transition) metal ion, metallomesogens can exhibit very interesting electrochemical, electronic or magnetic behaviour. Other properties of interest could be thermochromism, information storage and switching ability (in electric and/or magnetic fields). Most of the metallomesogens described in the literature are thermotropic liquid crystals. Lyotropic metallomesogens have been largely neglected so far. Many transition complexes have the right chemical structure to exhibit lyomesomorphism, not only in polar solvents but also in apolar solvents.

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Pyrazolate “Golden” Rings: Trinuclear Complexes That Form Columnar Mesophases at Room Temperature

Cited by 95 publications

References 12 publications

Pyrazole Complexes and Supramolecular Chemistry

Pyrazole Complexes and Supramolecular Chemistry

Synthesis of New Nondisk-Shaped Thermotropic Liquid Crystalline Compounds Showing a Rectangular Columnar Mesophase

Trimetallic Nickel–Lanthanum and Nickel–Gadolinium Metallomesogens

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