Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts

Mihelj, Tea; Tomašić, Vlasta; Biliškov, Nikola; Liu, Feng (2014) Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 124 . pp. 12-20. ISSN 1386-1425

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Abstract

18-crown-6 ether (18C6) complexes with the following anionic surfactants: sodium n-dodecylsulfate (18C6-NaDS), sodium 4-(1-pentylheptyl)benzenesulfonate (18C6-NaDBS) ; and potassium picrate (18C6-KP) were synthesized and studied in terms of their thermal and structural properties. Physico-chemical properties of new solid 1:1 coordination complexes were characterized by infrared (IR) spectroscopy, thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray diffraction and microscopic observations. The strength of coordination between Na+ and oxygen atoms of 18C6 ligand does not depend on anionic part of the surfactant, as established by thermodynamical parameters obtained by temperature-dependent IR spectroscopy. Each of these complexes exhibit different kinds of endothermic transitions in heating scan. Diffraction maxima obtained by SAXS and WAXS, refer the behavior of the compounds 18C6-NaDS and 18C6-NaDBS as smectic liquid crystalline. Distortion of 18C6-NaDS and 18C6-KP complexes occurs in two steps. Temperature of the decomplexation of solid crystal complex 18C6-KP is considerably higher than of mesophase complexes, 18C6-NaDS, and 18C6-NaDBS. The structural and liquid crystalline properties of novel 18-crown-ether complexes are function of anionic molecule geometry, type of chosen cation (Na+, K+), as well as architecture of self-organized aggregates. A good combination of crown ether unit and amphiphile may provide a possibility for preparing new functionalized materials, opening the research field of ion complexation and of host-guest type behavior.

Item Type:	Article
Uncontrolled Keywords:	18-crown-6 ether; IR spectroscopy; X-ray diffraction; anionic surfactants; thermal properties; liquid crystals
Subjects:	NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Physical Chemistry
Divisions:	Division of Materials Chemistry Division of Physical Chemistry
Projects:	Project title Project leader Project code Project type Surfactants, processes in solutions and at interfaces (Površinski aktivne tvari, procesi u otopinama i na međupovršinama)- Maja Dutour Sikirić 098-0982915-2949 MZOS Macrocyclic ligands, structures in solutions and molecular spectroscopies (Makrociklički ligandi, strukturne promjene otopina i molekularne spektroskopije)- Goran Baranović 098-0982904-2927 MZOS
Depositing User:	Tea Mihelj
Date Deposited:	01 Dec 2015 13:24
URI:	http://fulir.irb.hr/id/eprint/2341
DOI:	10.1016/j.saa.2013.12.092

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