Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts and potassium picrate.
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.
Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb, Croatia. Electronic address: tmihelj@irb.hr.
Tea
T
Mihelj
Department of Physical Chemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb, Croatia.
Vlasta
V
Tomašić
Division of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, POB 180, HR-10002 Zagreb, Croatia.
Nikola
N
Biliškov
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
Feng
F
Liu
D002614:Chelating Agents / Q000737:chemistry*; D043844:Crown Ethers / Q000737:chemistry*; D004055:Differential Thermal Analysis; D008024:Ligands; D010851:Picrates / Q000737:chemistry*; D012492:Salts / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature; D014961:X-Ray Diffraction
D002614:Chelating Agents; D043844:Crown Ethers; D008024:Ligands; D010851:Picrates; D012492:Salts; D013501:Surface-Active Agents; C015762:18-crown-6; D012964:Sodium; C005858:picric acid
18-crown-6 ether; Anionic surfactants; IR spectroscopy; Liquid crystals; Thermal properties; X-ray diffraction