Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals.

Electron and hole transport characteristics were evaluated for perylene-based and pyrene-based compounds using electron-only and hole-only devices. The perylene presented a columnar hexagonal liquid crystal phase at room temperature with strong molecular π-stacking inside the columns. The pyrene crystallizes bellow 166 °C, preserving the close-packed columnar rectangular structure of the mesophase. Photophysical analysis and numerical calculations assisted the interpretation of positive and negative charge carrier mobilities obtained from fitting the space charge limited regime of current vs voltage curves. The pyrene-based material demonstrated an electron mobility two orders of magnitude higher than the perylene one, indicating the potential of this class of materials as electron transporting layer.

Plank-shaped column-forming mesogens with substituents on one side only.

Prolonged glyoxylation of pyrenyl-1-glyoxylic acid ethyl ester leads to a mixture of isomers with polar pyrenylene-1,8-diglyoxylic acid as the main product, whereas the centrosymmetric 1,6-isomer is obtained in good yield from the corresponding dibromopyrene. Perkin condensations followed by Pd-catalyzed cyclizations lead to isomeric dinaphthopyrene-tetracarboxdiimides that self-assemble into columnar liquid crystals of hexagonal and rectangular symmetry, of which the rectangular mesophases have unusually elongated unit cells. The cisoid diimides with both alkylimide substituents on the same side of the oblong arene system show a much greater tendency to self-assemble into fluid stacks of disks than their centrosymmetric isomers. With racemically branched alkyl substituents, uniform vertical surface alignment of the columns in the high-temperature hexagonal mesophase is resilient to cycling through the lower-temperature rectangular and crystalline phases.

Columnar liquid-crystalline dinaphthoperylenetetracarboxdiimides.

Although the double Friedel-Crafts acylation of arenes with ethyl chloroglyoxylate is hindered by the strongly deactivating effect of the first-entering glyoxylic substituent, the double reaction is successful with the reactive arene perylene under long reaction times and with concomitant ester hydrolysis. The reaction is regiospecific, giving the 3,9-regioisomer exclusively. This perylenylenediglyoxylic acid is condensed first with o-bromophenylacetic acid and then with α-branched alkylamines to yield the title compounds. Whilst the corresponding tetraalkyl esters only show monotropic mesophases, these diimides show enantiotropic columnar mesophases that can be maintained at room temperature if racemically branched alkyl chains of moderate size are used. A palladium-induced C-C bond migration during the build-up of the arene system leads to an isomeric side product of reduced symmetry that can be isolated by aggregation-controlled chromatographic separation. The HOMO and LUMO energies of the title compounds are considerably higher than those of established perylenetetracarboxdiimides.

Label-Free Immunosensor Based on Liquid Crystal and Gold Nanoparticles for Cardiac Troponin I Detection.

According to the World Health Organization (WHO), cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity worldwide. The development of electrochemical biosensors for CVD markers detection, such as cardiac troponin I (cTnI), becomes an important diagnostic strategy. Thus, a glassy carbon electrode (GCE) was modified with columnar liquid crystal (LCcol) and gold nanoparticles stabilized in polyallylamine hydrochloride (AuNPs-PAH), and the surface was employed to evaluate the interaction of the cTnI antibody (anti-cTnI) and cTnI for detection in blood plasma. Morphological and electrochemical investigations were used in the characterization and optimization of the materials used in the construction of the immunosensor. The specific interaction of cTnI with the surface of the immunosensor containing anti-cTnI was monitored indirectly using a redox probe. The formation of the immunocomplex caused the suppression of the analytical signal, which was observed due to the insulating characteristics of the protein. The cTnI-immunosensor interaction showed linear responses from 0.01 to 0.3 ng mL-1 and a low limit of detection (LOD) of 0.005 ng mL-1 for linear sweep voltammetry (LSV) and 0.01 ng mL-1 for electrochemical impedance spectroscopy (EIS), showing good diagnostic capacity for point-of-care applications.

Enhancing the phosphorescence decay pathway of Cu(I) emitters - the role of copper-iodide moiety.

Speeding up the phosphorescence channel in luminescent copper(I) complexes has been extremely challenging due to the copper atoms relatively low spin-orbit coupling constant compared to heavier metals such as iridium. Here, we report the synthesis and characterization of three mononuclear copper(I) complexes with diimines, triphenylphosphine, and iodide ligands to evaluate the effect of the copper-iodide (Cu-I) moiety into the phosphorescence decay pathway. Temperature-dependent photophysical studies revealed combined thermally activated delayed fluorescence and phosphorescence emission, with a phosphorescence decay rate of the order of 104 s-1. Density functional theory calculations indicate very high spin-orbit coupling matrix elements between the low-lying states of these complexes. Compared to the classical [Cu(phen)(POP)]+, our results demonstrate that Cu-I is a versatile moiety to speed up the phosphorescence decay pathway in about one order of magnitude, and it can be prepared by a simplified synthetic route with few synthetic steps. Furthermore, the SOC matrix elements and the phosphorescence decay rates of these complexes are comparable to those of extensively applied coordination complexes based on heavier metals, making them a promising alternative as active layers of organic light-emitting diodes.

1-(5-Hydroxy-1-phenyl-3-trifluoromethyl-1H-pyrazol-1-yl)ethanone.

The crystal structure of the title compound, C(12)H(9)F(3)N(2)O(2), contains two independent mol-ecules in the asymmetric unit. The mol-ecules are chemically identical but exhibit a significant difference in the dihedral angles between the mean planes of the phenyl and pyrazole rings, with values of of 11.62 (13) and 18.17 (11)°. Moreover, the trifluoro-methyl group in one of the mol-ecules shows rotational disorder of the F atoms, with site occupancy factors of 0.929 (6) and 0.071 (6). The hydroxyl group in each of the mol-ecules shows a strong intra-molecular hydrogen bond with the carbonyl O atom, forming a six-membered ring and forcing the formyl group and pyrazole ring to be coplanarshowing C-C-C-O torsion angles of ?0.3(5)o and 0.°. Weak inter-molecular C-H⋯O and C-H⋯F inter-actions contribute to the stabilization of the crystal packing.

2-Phenyl-5-(trifluoro-meth-yl)pyrazol-3(2H)-one.

The title compound, C(10)H(7)F(3)N(2)O, is an analogue of pyrazolone derivatives with potential analgesic and anti-inflammatory properties. Its mol-ecular structure consists of phenyl and pyrazol-3(2H)-one units with a dihedral angle between the mean planes of the rings of 33.0 (1)°. The crystal structure is stabilized by an inter-molecular hydrogen bond between the N-H group and the carbonyl O atom of the pyrazol-3(2H)-one ring which links the mol-ecules into supra-molecular C(5) chains along [001] and by weak π-π stacking inter-actions between the phenyl rings [centroid-centroid distance = 3.881 (2) Å]. The F atoms are disordered over two positions with refined site occupancies of 0.768(11) and 0.232(11).

Recycled polyethylene terephthalate and aluminum anodizing sludge-based boards with flame resistance.

The objective of this study was to utilize polyethylene terephthalate (PET) and aluminum anodizing sludge (AAS) to produce fire-resistant polyurethane (PU) boards of different densities. Boards with 10%, 20%, 30%, 40% and 50% PET waste as a replacement for the PU raw material were prepared with the addition of 20% aluminum sludge. The products were checked by scanning electron microscopy (SEM) to show that the addition of residues modified the morphology of the alveoli and reduced the compressive strength of the rigid foams. The boards showed combustion deceleration up to flame extinction in the flammability test (UL94) because of the presence of the AAS. The influence of the fillers on the combustion of the specimens without and with 50% PET was observed through SEM images of the preserved and burnt regions of the materials. A reduction in the direct production costs of all the sheets was measured and reached close to 70% in the case of the board with the highest amount of added residues. Therefore, as a way to save natural resources and become more sustainable, it is suggested that the civil construction industry consider the addition of these residues as part of its formulations.