Thermodynamic properties of selenoether-functionalized ionic liquids and their use for the synthesis of zinc selenide nanoparticles

• Published in: Dalton transactions : an international journal of inorganic chemistry 2018, Vol.47 (14), p.583-597
• Main Authors: Klauke, Karsten, Zaitsau, Dzmitry H, Bülow, Mark, He, Li, Klopotowski, Maximilian, Knedel, Tim-Oliver, Barthel, Juri, Held, Christoph, Verevkin, Sergey P, Janiak, Christoph
• Format: Article
• Language: English
• Subjects: Anions; Aromatic compounds; Cations; Crystal structure; Enthalpy; Ionic liquids; Ions; Methylene; Nanoparticles; Selenium; Solubility parameters; Solvents; Thermodynamic properties; Vaporization; Zinc acetate; Zinc selenide
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt00233a

Three selenoether-functionalized ionic liquids (ILs) of N -[(phenylseleno)methylene]pyridinium ( 1 ), N -(methyl)- ( 2 ) and N -(butyl)- N '-[(phenylseleno)methylene]imidazolium ( 3 ) with bis(trifluoromethanesulfonyl)imide anions ([NTf 2 ]) were prepared from pyridine, N -methylimidazole and N -butylimidazole with in situ obtained phenylselenomethyl chloride, followed by ion exchange to give the desired compounds. The crystal structures of the bromide and tetraphenylborate salts of the above cations ( 1-Br , 2-BPh 4 and 3-BPh 4 ) confirm the formation of the desired cations and indicate a multitude of different supramolecular interactions besides the dominating Coulomb interactions between the cations and anions. The vaporization enthalpies of the synthesized [NTf 2 ]-containing ILs were determined by means of a quartz-crystal microbalance method (QCM) and their densities were measured with an oscillating U-tube. These thermodynamic data have been used to develop a method for assessment of miscibility of conventional solvents in the selenium-containing ILs by using Hildebrandt solubility parameters, as well as for modeling with the electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) method. Furthermore, structure-property relations between selenoether-functionalized and similarly shaped corresponding aryl-substituted imidazolium- and pyridinium-based ILs were analyzed and showed that the contribution of the selenium moiety to the enthalpy of vaporization of an IL is equal to the contribution of a methylene (CH 2 ) group. An incremental approach to predict vaporization enthalpies of ILs by a group contribution method has been developed. The reaction of these ILs with zinc acetate dihydrate under microwave irradiation led to ZnSe nanoparticles of an average diameter between 4 and 10 nm, depending on the reaction conditions. Predicting IL properties: Thermodynamically the Se atom in Se-ILs performs like a CH 2 group, but chemically it reacts as a source of Se.