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In this work, a calixarene based ionic liquid was successfully prepared and characterized by different techniques. This ionic liquid was used as an efficient catalyst for the synthesis of a series of polysubstituted pyridines from aldehydes, malononitrile, 1,3-diketones and arylamines in water as a green solvent. Also, for the first time, symmetric and unsymmetric polysubstituted bis-pyridines were obtained in high yields from diamines using this catalyst. Mild reaction conditions, high to excellent yields, easy work-up, excellent activity and reusability of the catalyst are the key features of this method which make it an interesting and novel alternative for the synthesis of the above... 

Solid-phase microextraction (SPME) is a fast, solvent-free technique, which, since its introduction in the 1990s, has been increasingly applied to sample preparation in analytical chemistry. Conventional SPME fibers are fabricated by making a physical bond between the usual silica substrate and the polymeric coatings. However, some applications are limited, as the lifetime and the stability of conventional SPME fibers cannot meet the demands of analyzing relatively non-volatile compounds with more polar moieties. There have been attempts to analyze less volatile compounds by increasing the thermal, physical and chemical stability of the fibers. In this review, we present some new...