Silver Pyrazolates as Coordination‐Polymer Luminescent Metallomesogens

Barberá, Joaquín; Lantero, Ignacio; Moyano, Sandra; Serrano, José Luís; Elduque, Anabel; Giménez, Raquel

doi:10.1002/chem.201001766

Cited by 32 publications

(31 citation statements)

References 70 publications

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“…The presence of several and bulky lipophilic side arms in the 3-and 5-positions of the pyrazolate units induces, after reaction with equimolar stoichiometric ratio of silver salts, the formation of neutral [AgL] p chain-coordination polymers, 2 [37]. None of the pyrazole ligands, with symmetrical (2: all R i = H or OC n H 2n+1 , R 1 = R 4 = OC n H 2n+1 , R 2 = R 3 = H) and nonsymmetrical (as in 2: R 1 -R 4 = H/OC n H 2n+1 ) substitution patterns, is mesomorphic but their coordination to silver(I) ion induces columnar (hexagonal and rectangular) LC organizations, in all derivatives (except those with only two lateral chains, 2, i.e., all R i = H), at RT and stable for a large range of temperature (with the clearing points decreasing from about 170 to 60 • C with increasing number of chains).…”

Section: Concepts In Molecular Designmentioning

confidence: 99%

Metal‐Containing Liquid Crystals

Pucci

Donnio

2014

Handbook of Liquid Crystals

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PreambleMetal-containing liquid crystals, commonly referred to as metallomesogens, a term invented by in the first comprehensive review on the subject, are metal complexes endowed with liquid crystalline (LC) properties. It is now well accepted that the first publication on metallomesogens was by Vorländer [2], who described in 1923 the smectogenic behavior of a series of Schiffbase complexes of diaryl mercury(II), despite earlier but sporadic publications on alkanoate magnesium salts by Heintz [3] and other related alkali metal soaps by Vorländer [4]. This field revived research interest half a century later with the concomitant pioneering publications by Malthête and Billard [5] on nematogenic ferrocene derivatives on the one hand and by Giroud and Mueller-Westerhoff on calamitic nickel(II) and platinum(II) dithiolene complexes (N and SmC phases) on the other hand [6].At first, metallomesogens were simply regarded as mere synthetic curiosities, but once the immense benefits of inserting metals into liquid crystals were acknowledged, activity in this field began to grow apace [1]. Metal-coordination of organic ligands indeed offers the possibility of obtaining a wide diversity of structures and functions (due to specific metal-metal, ligand-ligand, and metal-ligand synergies) as it is possible to combine a large range of potential organic ligands with metal ions of various numbers of coordination (NCs from 1 to 12). And indeed, numerous metallomesogens with new geometries (e.g., based on high coordination numbers) and shapes unattainable in organic systems diverging from standard calamitics and discotics, have been synthesized. Simultaneously, the use of multivalent ligands has also been more generalized and has led to intricate polymetallic systems that are expected to generate new functional supramolecular organizations. Evidently, metals are not limited to this purely structural role and, concomitantly to the production of metallomesogens with low transition temperatures and accessible mesophases, a wide range of physical properties (optical, magnetism, electronic, thermo-and solvatochromism, dichroism, conductivity, etc.), which crucially depend on the choice of the metal ion, can be exploited [7]. Incorporation of metals into modifications have led to new and sophisticated molecular structures, showing that the design of new LC materials is not restricted to simple shape anisotropies.The induction of preselected properties from the single molecular level to the supramolecular network in metal-containing materials is expected to expand the traditional range of technological applications of liquid crystals. It is currently possible to design new and better performing complexes whose structures, mostly unapproachable in purely organic LC systems, are able to induce low transition temperatures and modulate optical, electronic, magnetic, and thermal properties. Nowadays, the molecular design of metallomesogens is essentially based on the multimotif approach because of the spontaneous association of single func...

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Section: Concepts In Molecular Designmentioning

confidence: 99%

Metal‐Containing Liquid Crystals

Pucci

Donnio

2014

Handbook of Liquid Crystals

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“…During the last three decades the metallomesogens (metal-containing liquid crystalline molecules) of d-and f-block metals have attracted the attention of several research groups (1-10) because of their unusual geometries and novel properties such as colour, fluidity, large birefringence, polarisability, paramagnetism etc., in addition to functional properties such as spin cross-over (11), ferroelectricity (12), photorefractivity (13), non-linear optical characteristics (14), large magnetic anisotropy (15) and luminescent mesophases (16). In most of these materials extended salicylaldimine is utilised for complexation to yield mononuclear complexes with expected molecular properties.…”

Section: Introductionmentioning

confidence: 99%

Mononuclear and binuclear complexes of salicylidene Schiff bases: synthesis and mesogenic properties

et al. 2009

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The synthesis of new mononuclear and binuclear copper complexes derived from Schiff bases, namely N(4-nalkyloxysalicylidene)-4¢-n-alkylanilines is carried out and their structure and liquid crystalline properties have been investigated. The ligands exhibit rich polymesomorphism; mononuclear complexes exhibit smectic A, smectic C and smectic E phases, while the binuclear complexes mostly exhibit viscous smectic A phase. The isotropic-liquid crystalline transition temperatures of the binuclear complexes in general are found to be lower than their corresponding mononuclear homologues. It was found that the mononuclear complexes exhibit sharp liquid crystalline-isotropic transition temperatures while the binuclear complexes melts over a temperature range. The liquid crystalline phases were characterised by differential scanning calorimetry (DSC) analysis and optical polarised microscopy. X-ray diffraction studies revealed that the intermolecular distance in binuclear complexes is larger than in the mononuclear complexes.

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“…Metallomesogens have continued to captivate the scientific community during the last decade or so . This fascination is primarily linked to the potential applications of metallomesogens in OLEDs, information storage, sensors, and enhanced contrast displays ,,.…”

Section: Introductionmentioning

confidence: 99%

“…Metallomesogens have continued to captivate the scientific community during the last decade or so. [1][2][3][4][5][6][7] This fascination is primarily linked to the potential applications of metallomesogens in OLEDs, information storage, sensors, and enhanced contrast displays. [8,9,10] The structure and electronic properties of metallomesogens can be modified by tuning the coordination sphere of central metal atom.…”

Section: Introductionmentioning

confidence: 99%

Multifunctional Lanthanide Complexes: Mesomorphism, Photoluminescence and Second Order NLO Property

et al. 2018

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A series of new mononuclear multifunctional lanthanide(III)‐Schiff base complexes have been synthesized and characterized by elemental analyses, FTIR, 1H NMR and UV/Vis spectroscopy. Potentially tridentate, the Schiff‐base ligand is based on a ‘salicyldimine’ core with a long and flexible alkoxy group which coordinates to lanthanide ions in its zwitterionic form via the phenolic‐oxygen with the proton shifted to the imine‐nitrogen. The chelate nitrato groups complete a nine‐coordinate geometry. The ligand is non‐mesomorphic, while coordination to Ln3+ ion induces a liquid crystalline behavior. The complexes exhibited a thermally stable highly viscous partially bilayer smectic Ad phase in the 45‐135°C temperature range. The molecular organization of the complexes in the mesophase is conjectured to be based on a cylindrical‐like dimeric structure with the three alkoxy group pointing up and three pointing down assembling laterally into a lamellae. The Schiff base ligand is a blue light emitter exhibiting a broad emission maximum at 435 nm while the lanthanide complexes show an intense green emission. The Tb3+ complex, interestingly, also showed mesophase luminescence. The ligand and its complexes of La3+, Dy3+ and Yb3+ exhibited a significant second order non‐linear optical (NLO) activity representing the first example of lanthanidomesogens to exhibit such behaviour.

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Silver Pyrazolates as Coordination‐Polymer Luminescent Metallomesogens

Cited by 32 publications

References 70 publications

Metal‐Containing Liquid Crystals

Metal‐Containing Liquid Crystals

Mononuclear and binuclear complexes of salicylidene Schiff bases: synthesis and mesogenic properties

Multifunctional Lanthanide Complexes: Mesomorphism, Photoluminescence and Second Order NLO Property

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