Thermal Behaviour and Structural Properties of Surfactant - Picrate Compounds: the effect of the ammonium headgroup number

Tomašić, Vlasta; Biliškov, Nikola; Mihelj, Tea; Štefanić, Zoran (2013) Thermal Behaviour and Structural Properties of Surfactant - Picrate Compounds: the effect of the ammonium headgroup number. Thermochimica Acta, 569 . pp. 25-35. ISSN 0040-6031

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Abstract

Novel quaternary n-dodecyldimethylammonium picrates with two to four chains connected by an ethylene spacer at the ammonium headgroup level were synthesized. The effect of the headgroup number and the impact of picrate anion to their physicochemical properties was examined. Crystal structure of dimeric dipicrate is significantly different from bromide analogue. The dominant feature of this crystal packing is a layered structure with aromatic rings of picrate molecules, stacked via strong π•••π interactions and connected to the alkylammonium molecules with their nitro groups by C-H•••O hydrogen bonds. Weak NO2···HC hydrogen bonds further stabilize the structure. Higher degree of oligomerization leads to the less ordered solid phase and amorphous picrate structure. These amorphous structures result from widespread and disordered hydrogen bonding and rupture of π-π stacking in samples with more than two headgroups. Unlike corresponding bromides, picrate compounds show reversible phase transitions without thermal decomposition. Temperature-dependent infrared spectroscopy in the liquid phase detected adiabatic phase transitions.

Item Type:	Article
Additional Information:	NOTICE: this is the author’s version of a work that was accepted for publication in Thermochimica Acta. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Thermochimica Acta, [569, (2013)] DOI: 10.1016/j.tca.2013.06.041.
Uncontrolled Keywords:	picric acid; cationic oligomeric surfactant; infrared spectroscopy; thermal analysis; 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 [231293] Maja Dutour Sikirić 098-0982915-2949 MZOS Metalni hidridi u čistim energetskim sustavima [28751] Antun Drašner 098-0982904-2941 MZOS
Depositing User:	Nikola Biliškov
Date Deposited:	06 Nov 2013 17:11
URI:	http://fulir.irb.hr/id/eprint/896
DOI:	10.1016/j.tca.2013.06.041

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