Thermal and structural properties of surfactant–picrate compounds

Mihelj, Tea; Štefanić, Zoran; Tomašić, Vlasta (2012) Thermal and structural properties of surfactant–picrate compounds. Journal of Thermal Analysis and Calorimetry, 108 (3). pp. 1261-1272. ISSN 0022-5215

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Abstract

The novel surfactant–picrate compounds were synthesized and characterized by thermal and XRD analysis.The synthesis, based on the electrostatic interactions of components in polar solvents, was carried out using picric acid and cationic surfactants (dodecyltrimethylammonium, didodecyldimethylammonium, and tridodecylmethylammonium halide). The idea was to investigate the dependence of physico-chemical properties and thermal transitions of picrate–surfactant compounds with raising number of dodecyl chains sited on the same ammonium head group. The equimolar mixed aqueous solutions are characterized as lyotropic, strongly promoted by picrate anion. The main crystal structure feature of investigated picrates is layered structure with stacked aromatic rings of one picrate molecule on the top of the other one via strong π…π interactions and connection to the alkylammonium molecules with their nitro groups by C–H…O hydrogen bonds. Surfactant–picrate bilayer-like structures are interrupted with layers of polar heads and picrate counterions and the observed width of such a bilayers are functions of more complex structural behaviors which ensures alternation in space of equal numbers of positive and negative charges. Although some of the surfactants used posses thermotropic properties, like examined tridodecylmethylammonium chloride, no thermotropic mesomorphism is detected in solid state of investigated surfactant–picrate compounds. The thermodynamic parameters of solid–liquid thermal transitions depend linear on the number of dodecyl chains, and for double- and triple-tailed picrate compounds the marked temporal hysteresis of the melt crystallization is registered.

Item Type:	Article
Uncontrolled Keywords:	thermal analysis; alkyl chain number; cationic surfactant; picrate; crystal structure
Subjects:	NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Physical Chemistry
Divisions:	Division of Physical Chemistry
Projects:	Project title Project leader Project code Project type Površinski aktivne tvari, procesi u otopinama i na međupovršinama- Maja Dutour Sikirić 098-0982915-2949 MZOS Protein-ligand međudjelovanja na atomnoj razini- Marija Luić 098-1191344-2943 MZOS
Depositing User:	Tea Mihelj
Date Deposited:	10 Jan 2017 09:34
URI:	http://fulir.irb.hr/id/eprint/2346
DOI:	10.1007/s10973-011-1710-7

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