Effect of counterion on the mesomorphic behavior and optical properties of columnar pyridinium ionic liquid crystals derived from 4-hydroxypyridine

Pană, Amalia; Chiriac, Florentina Laura; Iliş, Monica; Staicu, Teodora; Micutz, Marin; Pasuk, Iuliana; Cı̂rcu, Viorel

doi:10.1016/j.molstruc.2014.11.059

Cited by 22 publications

(17 citation statements)

References 21 publications

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“…The synthetic procedure for the 4-pyridone ligands 2a – c involved the reaction between the 4-hydroxypyridine and the corresponding bromide derivative, 4-(ω-bromoalkyloxy)-biphenyl derivatives for 2a , b and benzyl bromide for 2c , in the presence of NaOH and tetrabutylammonium bromide (TBABr) as phase transfer catalyst ( Scheme 1 ) [ 9 , 24 , 35 ].…”

Section: Resultsmentioning

confidence: 99%

Thermal and Emission Properties of a Series of Lanthanides Complexes with N-Biphenyl-Alkylated-4-Pyridone Ligands: Crystal Structure of a Terbium Complex with N-Benzyl-4-Pyridone

et al. 2021

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This work focuses on the investigation of the liquid crystalline behavior and luminescence properties of the lanthanide complexes of Eu(III), Sm(III) and Tb(III) with N-biphenyl-alkylated-4-pyridone ligands. The organic ligands having a biphenyl group attached via a long flexible spacer with either 9 or 10 carbon atoms were synthesized by the reaction between 4-hydroxypyridine and the corresponding bromide compounds. The chemical structures of the organic and lanthanide complexes were assigned based on elemental analysis, single-crystal X-ray diffraction, 1H, 13C NMR and IR spectroscopies, and thermogravimetric analysis (TGA). The X-ray diffraction analysis of a parent compound shows that the lanthanide ions are surrounded by three monodentate pyridone ligands and three bidentate nitrate ions, giving a 9-coordinate environment. The mesogenic behavior and the type of liquid crystalline phases exhibited by the new complexes were analyzed by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM), and powder X-ray diffraction (XRD) studies. Only the lanthanide complexes with longer spacer (10) display a monotropic SmA phase, typically on a short thermal range (less than 10 °C). The complexes with shorter flexible chains (9) show no liquid crystalline properties with melting temperatures lower than their analogs with longer spacers. The emission spectra recorded in solid state at room temperatures show typical emission bands for each lanthanide ion employed (Eu(III), Tb(III) and Sm(III)).

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Section: Resultsmentioning

confidence: 99%

Thermal and Emission Properties of a Series of Lanthanides Complexes with N-Biphenyl-Alkylated-4-Pyridone Ligands: Crystal Structure of a Terbium Complex with N-Benzyl-4-Pyridone

et al. 2021

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“…The new monodentate ligands having three alkoxyl chains with variable number of carbon atoms were prepared through the reaction of 4‐hydroxypyridine with 3,4,5‐tris(alkyloxy)benzyl bromide derivatives in THF in the presence of NaOH and tetrabutylammonium bromide (TBABr) as phase‐transfer catalyst to give 4‐pyridone derivatives PyO‐ n as the main product in 65–70 % yield (Scheme ) . All N ‐alkylated 4‐pyridone derivatives were fully characterized by 1 H and 13 C NMR and IR spectroscopy as well as by elemental analysis.…”

Section: Resultsmentioning

confidence: 99%

“…The PyO‐ n ( n =6, 8, 10, 12, 14, 16) ligands were prepared by a slightly modified known procedure . A 2 n aqueous solution of sodium hydroxide was added to a solution of 4‐hydroxypyridine and tetrabutylammonium bromide (phase‐transfer catalyst) in THF.…”

Section: Methodsmentioning

confidence: 99%

Wide‐Range Columnar and Lamellar Photoluminescent Liquid‐Crystalline Lanthanide Complexes with Mesogenic 4‐Pyridone Derivatives

Chiriac

Pasuk

Secu

et al. 2018

Chemistry A European J

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A series of liquid crystals with various lanthanide ions (Eu , Sm , and Tb ) was designed and prepared starting from the corresponding lanthanide nitrates and N-alkylated 4-pyridone derivatives bearing mesogenic 3,4,5-tris(alkyloxy)benzyl moieties (alkyl=hexyl, octyl, decyl, dodecyl, tetradecyl, or hexadecyl). These new lanthanidomesogens were investigated for their mesogenic properties by a combination of differential scanning calorimetry, polarizing optical microscopy, and temperature-dependent powder X-ray diffraction (XRD). Their thermal stability was assessed by thermogravimetric analysis. All of these complexes show enantiotropic liquid-crystalline behavior with lamellar (SmA) phases in the case of shorter-chain complexes (C and C ) or hexagonal columnar phases (Col ) for complexes with longer alkyl chains (C , C , and C ), which were assigned on the basis of their characteristic textures and XRD studies. For complexes with an intermediate number of carbon atoms in the side chains (C ), both a lamellar phase at lower temperatures and a Col phase at higher temperatures were evidenced. In the solid state, all these complexes show characteristic emissions assigned to the corresponding lanthanide ion. In addition, the luminescence decay curves showed single-exponential decays with characteristic times in the millisecond range (0.75-0.90 ms for Eu , 0.045-0.060 ms for Sm , and 0.75-1.05 ms for Tb ).

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“…The variation of the counterion is reported to have a profound effect on the mesomorphism of ILCs . We thus investigated the symmetrical acyclic guanidinium salts 3(14 , 14)X with different counterions by DSC in comparison with the chloride 3(14 , 14)Cl (Table , entries 5, 13–17, Figure ).…”

Section: Resultsmentioning

confidence: 99%

Tyrosine‐Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion

Neidhardt

Wolfrum

Beardsworth

et al. 2016

Chemistry A European J

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Synthetic strategies were developed to prepare l-tyrosine-based ionic liquid crystals with structural variations at the carboxylic and phenolic OH groups as well as the amino functionality. Salt metathesis additionally led to counterion variation. The liquid-crystalline properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS, SAXS). The symmetrical ILC chlorides bearing the same alkyl chain at both the ester and ether but either an acyclic or cyclic guanidinium group displayed enantiotropic SmA mesophases with phase widths of 31-88 K irrespective of the head group. It was particularly the replacement of chloride in the acyclic guanidinium ILC by hexafluorophosphate that induced a phase change from SmA to Col . This phase change was attributed to a higher curvature of the interface due to the larger anion, which increased the effective head group cross-sectional area of the amphiphilic ILC. The unsymmetrical acyclic guanidinium chlorides, bearing a constant C ester and variable alkyl chains on the phenolic position, formed enantiotropic SmA phases. The derivative with the largest difference in chain lengths, however, displayed a Col phase, resulting from discoid aggregates of the cone-shaped guanidinium chloride. The results are discussed in terms of the packing parameters, which indicate that the phase behaviour of the thermotropic tyrosine-based ILCs shows analogies to those of lyotropic liquid crystals.

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Effect of counterion on the mesomorphic behavior and optical properties of columnar pyridinium ionic liquid crystals derived from 4-hydroxypyridine

Cited by 22 publications

References 21 publications

Thermal and Emission Properties of a Series of Lanthanides Complexes with N-Biphenyl-Alkylated-4-Pyridone Ligands: Crystal Structure of a Terbium Complex with N-Benzyl-4-Pyridone

Thermal and Emission Properties of a Series of Lanthanides Complexes with N-Biphenyl-Alkylated-4-Pyridone Ligands: Crystal Structure of a Terbium Complex with N-Benzyl-4-Pyridone

Wide‐Range Columnar and Lamellar Photoluminescent Liquid‐Crystalline Lanthanide Complexes with Mesogenic 4‐Pyridone Derivatives

Tyrosine‐Based Ionic Liquid Crystals: Switching from a Smectic A to a Columnar Mesophase by Exchange of the Spherical Counterion

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