Calix[4]resorcinarene macrocycles: Synthesis, thermal behavior and crystalline characterization

Supramolecular chemistry is an interdisciplinary scientific field, including chemical, physical and biological properties of more complex chemical species than the molecules themselves. Calixarenes/calixresorcinarenes are macrocyclic compounds, consisting of n' phenolic/resorcinolic units linked together by methylene bridges; these macrocycles are often used for molecular recognition. Thus, different modifications can be made to both the lower and upper rim, allowing the construction of well-defined multivalent buildings. In this work, three calix[4]resorcinarene macrocycles were synthesized, namely C-dec-9-en-1-ylcalix[4]resorcinarene (CAL 11U), C-trans-2, cis-6-octa-1,5-dien-1-ylcalix[4]resorcinarene (CAL 9U) and C-nonylcalix[4]resorcinarene (CAL 10) by a simple condensation reaction. The compounds CAL 11U and CAL 10 have been already synthesized by researchers, while the CAL 9U has been synthesized for the first time. Their structures were confirmed using ATR-FTIR, H-1 NMR and C-13 NMR. Thermal analysis combined with mass spectrometric evolved analysis of the vapors was used to study the thermal behavior of the different synthesized molecules, and they were the subject of characterization by X-ray powder diffraction in order to analyze their degree of crystallinity.