Volume 24, Issue 51 p. 13512-13522
Full Paper

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

Laura F. Chiriac

Laura F. Chiriac

Department of Inorganic Chemistry, University of Bucharest, 23 Dumbrava Rosie St., Bucharest, Sector 2, 020484 Romania

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Dr. Iuliana Pasuk

Dr. Iuliana Pasuk

National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele, Romania

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Dr. Mihail Secu

Dr. Mihail Secu

National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele, Romania

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Dr. Marin Micutz

Dr. Marin Micutz

Department of Physical Chemistry, University of Bucharest, 4–12 Elisabeta Blvd., 030018 Bucharest, Romania

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Dr. Viorel Cîrcu

Corresponding Author

Dr. Viorel Cîrcu

Department of Inorganic Chemistry, University of Bucharest, 23 Dumbrava Rosie St., Bucharest, Sector 2, 020484 Romania

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First published: 19 June 2018
Citations: 9

Graphical Abstract

Luminescent lanthanidomesogens: A series of novel luminescent columnar lanthanidomesogens based on EuIII, SmIII, and TbIII nitrates and N-alkylated 4-pyridone ligands bearing mesogenic 3,4,5-tris (alkyloxy)benzyl moieties (alkyl=hexyl, octyl, decyl, dodecyl, tetradecyl, or hexadecyl) was designed and synthesized, and their mesogenic properties were studied (see figure).

Abstract

A series of liquid crystals with various lanthanide ions (EuIII, SmIII, and TbIII) 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 (C6 and C8) or hexagonal columnar phases (Colh) for complexes with longer alkyl chains (C12, C14, and C16), 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 (C10), both a lamellar phase at lower temperatures and a Colh 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 EuIII, 0.045–0.060 ms for SmIII, and 0.75–1.05 ms for TbIII).

Conflict of interest

The authors declare no conflict of interest.