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Liquid crystal macrocycles (LCMs) combine the unique properties of liquid crystals with those associated with macrocyclic compounds—shape persistence and the capability of hosting small molecules. Herein, we investigate the grafting of coumarin-containing promesogenic moieties to pillar[5]arene as a strategy to obtain multifunctional LCMs. Pillar[5]arenes containing 10 and 30 coumarin units are glassy materials with nematic mesomorphism. Moreover, the coumarin moieties afford the pillar[5]arene derivatives with enhanced film-forming and photoresponsive properties. Photodimerization of the coumarin moieties results in cross-linked polymer networks, which can be used as alignment layers. Therefore, liquid-crystal coumarin-containing pillar[5]arenes represent a significant addition to the family of LCMs and may become useful for the development of engineered, hierarchical structures and materials.

Analizar el desarrollo y la evaluación de los resultados de la implementación del trabajo fin de grado (TFG) en el grado de enfermería (2010-2014) de la Universidad Autónoma de Madrid, así como explorar los factores que influyen en la evaluación global del TFG (EGT) y en las puntuaciones de las competencias alcanzadas en la memoria y la defensa.

Identificar las intervenciones más efectivas en adultos con sobrepeso y obesidad.

Describir la experiencia del cuidado de las mujeres cuidadoras con procesos crónicos de salud que cuidan de un familiar dependiente.

The synthesis and characterization of ionic liquid crystalline dendritic polymers based on the ammonium salts of commercially available poly(propylene imine) (PPI), poly(amidoamine) (PAMAM), poly(ethyleneimine) (PEI), and the fully methylated PEI (PEIMe) with 5‐(4‐cyanobiphenoxy)pentanoic acid (CBPA) are reported. The occurrence of proton transfer from the carboxylic acid to the amine groups is confirmed using IR and NMR techniques. The mesomorphic behavior is investigated by means of differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffractometry. Although CBPA exhibits monotropic nematic mesomorphism, all ionic complexes display enantiotropic liquid crystal properties. The relationship between the mesomorphism of the complexes and their structure is discussed.

A new series of extended dithieno[3,2‐b:2',3'‐d]phospholes with dendritic and non‐dendritic architectures involving phenylenevinylene as well as Fréchet‐type dendrons is presented. Modification of the phosphorus center with Pd allows for the generation of a dimeric dendrimer with Pd‐center. The synthetic strategy employed balances the rigid main scaffold with the flexibility of the dendrons in order to keep control of supramolecular self‐organization features. All the structures show a high photoluminescence in both solution and solid state, which is further intensified via energy transfer from the dendrons to the core. In terms of self‐organization in solution, three of the derivatives which bear an extended phosphole unit as common moiety are able to gel a variety of organic solvents at room temperature independently from the nature of their substituents. Notwithstanding, the dimeric dendrimer with Fréchet‐type dendrons is only able to display gel properties at low temperature. All gels exhibit pronounced photoluminescence properties that can be tuned by variation of the solvent and the temperature. In absence of solvent, the phosphole derivatives exhibit, moreover, liquid‐crystalline mesomorphism features. While three of the compounds present stable and highly luminescent columnar hexagonal phases at room temperature, the fourth species was found to be crystalline in the thermal range up to its isotropic state. Finally as proof of concept, the multifunctionality of these materials is demonstrated in an electrochromic device.

Molekulares Tauziehentritt zwischen nicht‐ und teilfluorierten Alkylketten auf, wenn sie durch ionisches Anbinden an ein Polypropylenimin‐Dendrimer zu großer Nähe gezwungen werden. Der Wettkampf der beiden Substituenten um die Steuerung der supramolekularen Organisation der Moleküle führt zu unerwarteten mesomorphen Eigenschaften.

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The synthesis and characterization of a new family of ionic liquid crystal dendrimers consisting of the ammonium salts of the commercially available poly(propylene imine) (G = 1−5) dendrimers and 4-decyloxy-, 3,4-didecyloxy-, and 3,4,5-tridecyloxybenzoic acids are reported. The liquid crystalline behavior was investigated by means of differential scanning calorimetry, polarizing-light optical microscopy, and X-ray diffractometry. Dendrimers with mono- and didecyloxybenzoate moieties show lamellar mesomorphism, namely, smectic A, whereas those with tridecyloxybenzoate units show columnar mesomorphism:  rectangular for G = 1 and hexagonal for G = 2−5. On the basis of the experimental results, we propose models both at the molecular level and in the mesophase for all the materials.

Two families of liquid crystal dendrimers consisting of a dendrimeric core fourth and fifth generations of poly(amidoamine) (PAMAM) and poly(propyleneimine) (DAB) and several large-sized mesogenic units (incorporating three, six, and nine terminal alkoxy chains) have been prepared. The study of these materials reveals the existence of a hexagonal columnar mesomorphism in all cases. We propose a model to explain this behavior based on theoretical calculations made from experimental X-ray diffraction data. The plasticity of the dendrimeric cores, related to their conformational freedom, allows the macromolecules to adopt a cylindrical shape in which the mesogenic units are accommodated around the central core. As a result of this cylindrical symmetry of the molecules, a supramolecular columnar arrangement is present in the mesophase. A complete degree of functionalization of some of the dendrimers would prevent the appearance of a columnar mesophase according to our model. However, we have found that, in all cases, the number of promesogenic units attached to the dendrimer cores is lower than that possible, which permits the cylindrical arrangement of the macromolecules and the existence of columnar mesomorphism.

Summary:A nematic liquid crystalline network based on a poly(propylene imine) dendrimer [PPI‐(NH2)32(G = 4)] was prepared in the form of films. In the network the PPI dendritic molecules are partially functionalised with a chiral aldehyde and are connected to each other by an achiral dialdehyde. The phase behaviour of the network was investigated by polarising‐light optical microscopy, differential scanning calorimetry, and X‐ray diffractometry. Thermoelastic measurements ruled out the possible elastomeric nature of the material.

In this article, we review some of our recent work on the development and study of the properties of self-organizing supermolecular liquid crystalline dendritic materials. Prior to this purpose, the state of the art in the field of molecular design, structure and properties of liquid-crystalline dendrimers LCDs will be briefly reviewed, and illustrated by a selection of pioneering examples. The first type of LC dendrimer takes into account the location of their functional elements mesogens in the periphery of the macromolecules and its topology of attachment, and the nature of the mesogen. We will show how functionality can be in-built into such materials so that self-organising functional systems can be created. Side-chain liquid-crystalline dendrimers exhibiting lamellar, columnar and nematic phases are shown. The mechanism of mesophase formation mesogen interaction versusmicrophase separation is also discussed in relation to the molecular structure the nature of the mesogen and of the dendritic matrix, dendritic generation number. The second type of LC dendrimer introduced presents a different topology in that the mesogens are now inserted within the dendritic matrix and in the periphery. Owing to their particular constitution, it will be shown that the mesophases of the lamellar and columnar types possess unusual morphologies.

The synthesis of new metal complexes based on imines derived from tris-(2-aminoethyl)amine (TREN) which exhibit different geometries depending on the metal [Cu(ii), VO(iv), Pd(ii), Ni(ii), Ln(iii)] has been carried out. TREN has three coordination positions which allow us to obtain different coordination complexes involving one, two or three metallic centres. The molecular structure and purity of these novel compounds have been verified by IR, 1H and 13C NMR and elemental analysis and electro-spray mass spectrometry. The phase behaviour was studied by polarizing optical microscopy, differential scanning calorimetry (DSC) and X-ray diffraction techniques. It was found that the transition metal complexes display a smectic C mesophase whereas the lanthanide complexes display an unidentified smectic mesophase.

The synthesis of new metal complexes based on imines derived from tris-(2-aminoethyl)amine (TREN) which exhibit different geometries depending on the metal [Cu(ii), VO(iv), Pd(ii), Ni(ii), Ln(iii)] has been carried out. TREN has three coordination positions which allow us to obtain different coordination complexes involving one, two or three metallic centres. The molecular structure and purity of these novel compounds have been verified by IR, 1H and 13C NMR and elemental analysis and electro-spray mass spectrometry. The phase behaviour was studied by polarizing optical microscopy, differential scanning calorimetry (DSC) and X-ray diffraction techniques. It was found that the transition metal complexes display a smectic C mesophase whereas the lanthanide complexes display an unidentified smectic mesophase.

The synthesis and liquid crystalline behaviour of several sixteen-branched dendrimers based on poly(amidoamine) (PAMAM) and poly(propyleneimine) (DAB) are reported. Mono-, di- and trialkoxybenzoyloxysalicylaldehydes are used as mesogenic promotor moieties and are attached at the peripheral amino groups of the pre-existing dendrimers. All the compounds exhibit liquid crystalline properties which were studied by optical microscopy, DSC and X-ray diffraction. The relationship between the structure of the mesogenic units and the mesomorphic behaviour is discussed and models for the different supramolecular organizations are proposed.

AbstractA series of compounds of the formula [MnCl(Ln)2] (L= N-alkyl[4-(4-decyloxybenzoyloxy)]salicylaldiminato) have been synthesized and their mesomorphic properties studied. These Mn(III) complexes display monotropic nematic phases when the number of carbon atoms of the N-alkyl moiety has from 3 to 9 carbon atoms. Compounds ranging from 5 to 9 carbon atoms also display monotropic smectic C phases. When the N-alkyl part is longer (10 to 16 carbon atoms) only enantiotropic smectic C phases appear. Two complexes were studied by X-ray diffraction showing diffraction patterns that account for the peculiar molecular shape of these molecules.

A new series of liquid crystalline poly(amidoamine) (PAMAM) dendrimers is described. These dendrimers are made by attaching to the 0‐, 1‐, 2‐, 3‐, and 4‐generation of PAMAM‐terminal promesogenic units that carry two decyloxy chains in the 3‐ and 4‐positions of their peripheral aromatic ring. X‐ray diffraction studies show that all the compounds display a hexagonal columnar mesophase. A high density of aliphatic chains imposes a curved interface with the promesogenic units that forces the molecules to adopt a radial conformation, and therefore, the columnar structure. A model for the supramolecular organization of the different generations within the columnar mesophase is proposed based on the variation of some of the structural parameters.

Poly(amidoamine) starburst dendrimerswhich contain peripheral mesogenic ester units were found to exhibit a smectic A mesophase. A structural model is proposed that is valid for several generations of dendrimers. The mesogenic units form parallel aggregations that give rise to the smectic structure (shown schematically).

A new range of transition metal-containing liquid crystals is formed by complexing classical organic mesogens directly to a metal. Thus, reaction of [PdCl2(PhCN)2] with 4-n-pentyl-4'-cyanobiphenyl (5CB) leads to [PdCl2(5CB)2] which exhibits a monotropic nematic phase. Complexes of long chain 4-alkyloxy-4'-cyanobiphenyls show enantiotropic mesophases. Analogously, reaction of [PtCl2(PhCN)2] or [Rh2Cl2(CO)4] with 4-alkyl-4'-cyanobiphenyls (L) yields mesogenic [PtCl2L2] or cis-[RhCl(CO)2 L] respectively. The crystal and molecular structure of [PdCl2(5CB)2] and [PtCl2(8CB)2] are also reported and show different packing in the solid state.

New ferroelectric compounds have been prepared by the esterification of 4-alkoxy-2,2',4'-trihydroxybenzala-zines with R-2-chloropropanoyl chloride obtained from L(+)-lactic acid. These substances exhibit chiral smectic C phase and smectic A and their phase transition temperatures and enthalpies were determined. A preliminary characterization of the ferroelectric properties of these compounds has been carried out by studying their response times as a function of temperature at several voltages.

Two new series of compounds that have mesomorphic properties were synthesized: the 4-alkoxy-4' -alkyl-2-hydroxy-α, α'-dimethyl-benzalazines and the 4-alkoxy (n)-4'-alkoxy(m)-2-hydroxy-α, α'-dimethylbenzalazines. Thermodynamic measurements were made, all the compounds gave lower melting points and larger mesophase ranges than the symmetrically substituted compound.The dialkoxy (n-m)substituted compounds exhibit polymorphism in the solid state.

The synthesis and mesogenic behaviour of Copper (II) complexes derived from polar Schiff bases and of their corresponding ligands are reported. The ligands exhibited smectic C, smectic A and nematic phases, whereas the complexes only showed smectic A and nematic phases: Optical investigations carried out with one of the complexes showed that the nematic phase was uniaxial.

A new type of mesogen intermediate, the 5-n-alkoxy-2-pyridinecarboxaldehydes, has been synthesized. Three homologous series of derivatives were prepared and their mesomorphic properties studied: Schiff's monobases (5-n-alkoxy-2-pyridylmethylene-4'-n-alkoxyanilines), Schiff's dihases (bis-(5'-n-alkoxy-2'-pyridylmethylene)-1,4-phenylenediamines) and azines (his-(5-n-alkoxy-2-pyridylmethylene)-hydrazines). These derivatives are all mesogenic. The principal phases formed are nematic but, to a lesser extent, smectic C phases occur also. In some cases smectic A, B, G and H phases were detected.

Binary, ternary, and quaternary mixtures of four nematogenic compounds, 2-hydroxy-4,4′-dihexoxy-α,α′-dimethylbenzalazine, 4′-butyl-2-hydroxy-4-octoxy-α,α′-dimethylbenzalazine, S-4′-butoxy-2-hydroxy-4-(2-rnethylbutoxy)-α,α′-dimethylbenzalazine, and 2-hydroxy-4′-nitro-4-octoxy-α,α′-dimethylbenzalazine, were studied. In the mixtures with a nitro group a SA-induced phase appeared.These systems of mixtures were studied using the Scheffé algorithm. A comparative study of the prediction methods of the eutectic points was made.

Two new series of compounds with mesomorphic properties were synthesized; the 4-ethoxy and 4-octyloxy-4′-X-2-hydroxy-α,α′-dimethylbenzalazines (X = CN, NO2, F, Cl, Br, CH3, and N(CH3)2). Thermodynamic measurements were made. All the compounds gave mesogenic behaviour. Some of them exhibit polymorphism in the solid state, A study of the existent correlation between the temperatures at which the N–I transition appears in five series of mesogenic compounds and electronic parameters of the polar terminal chain was carried out. Seven terminal groups were studied: —F, —Cl, —Br, —CH3, —OCH3, —NO2, and —CN. None of the electronic parameters used enabled us to obtain a good correlation with all the groups. However, when the methoxy group was omitted, the parameters that measured π electronic delocalization in the aromatic ring showed an excellent correlation with the TN–I. The best correlation was obtained in all cases with Swain and Lupton's , which defined the resonance effect.

Four homologous series of flexible main-chain polyethers derived from benzalazines are reported. Enantiotropic nematic phases were found for three of the series. The influence of molecular structure on the mesomorphic properties has been studied. A comparative study is made between their properties and those of the analogous small molecules. The existence of OH group in positions 2,2' of the azine central core made it difficult to synthesize the polymers using the phase transfer catalysis method and consequently a new method was employed.

The synthesis, characterization and thermal behaviour of several new series of copper(II) complexes derived from carbonylic compounds and their Schiff's bases are reported. The complexes are of two types; [Cu(C6H3O(R)-C(X) = O)2], (type I) and [Cu(C6H3O(R)-C(X) = N-R')2] (type II) where R = - OOC-C6H4OC10H21-p, and the position of R is 4 or 5; R' = CH3, n-C10H21, p-n-C10H21O(C6H4)-; X = H, CH3. In type I complexes, only the compound with X = H and R in position 5 showed mesomorphism. For type II complexes, all the Schiff's bases complexes of copper(II) derived from 2,4-dihydroxybenzaldehyde showed thermotropic mesophases (smectic C and nematic), whereas the complexes derived from 2,5-dihydroxybenzaldehyde were only mesogenic when the imine was derived from methylamine. None of the complexes derived from the ketone (2,4 or 2,5-dihydroxy derivatives) showed liquid-crystalline properties. X-ray studies of four complexes of type II were carried out. The anisotropy of the magnetic susceptibility has a negative sign for complexes with R in position 4 and a positive sign for 2,5-derivative complexes. The relationship between molecular structure and mesomorphic behaviour is discussed.

We present a comparative study of various metallomesogenic complexes, using X-ray diffraction methods. For a given ligand linked to different metal atoms (Cu, Ni, VO), the nature of this central atom influences mainly the magnetic susceptibilities of the mesophases. With different ligands, which keep the close neighbourhood of the metal atom unchanged, the apparent length of the mesogenic unit is longer for short ligands than for longer ones. This unexpected behaviour is qualitatively well explained by taking into account the global shape of the different complexes.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.