Lower rim dimerization of a calixarene through the encapsulation of sodium ions

Abstract

Here we report the tail-to-tail dimerization of tetra-IJcarboxymethoxy)calixij4]arene in both solution and solid state phases using ESI-orbitrap UHRMS, 1 H-NMR and single-crystal X-ray diffraction techniques. Three sodium ions are encapsulated into the dimeric structure which is also stabilized by hydrogen bonds between carboxyl moieties undergoing partial deprotonation.

Exploring the structural landscape of 2-(thiophen-2-yl)-1,3-benzothiazole: high-Z′ packing polymorphism and cocrystallization with calix[4]tube

“…Both benzothiazole and calixarene were previously synthesized and characterized by our research group. The synthetic paths and characterization data can be found in full detail in previous publications (Martins et al, 2016;Pereira Araujo et al, 2015). Cocrystallization screenings with 2-(thiophen-2-yl)-1,3-benzothiazole were set with CX4A (already as the sodium salt) (Martins et al, 2016) as host.…”

“…The synthetic paths and characterization data can be found in full detail in previous publications (Martins et al, 2016;Pereira Araujo et al, 2015). Cocrystallization screenings with 2-(thiophen-2-yl)-1,3-benzothiazole were set with CX4A (already as the sodium salt) (Martins et al, 2016) as host. Such assays involved a change in the ratio between the benzothiazole and calixarene, and different solvent combinations.…”

“…These compounds are made up of aromatic rings bonded through methylene bridges in a macrocyclic structure (Gutsche et al, 1981). Their versatility is in part associated with possible functionalization in the upper and lower rims, increasing the selectivity for specific guests (Atwood et al, 2002;Martins et al, 2016). Likewise, methylene bridges enable different conformations of calix [n]arenes, resulting in the possibility of a wide range of guest molecules being included (Ř ezanková et al, 2017;Martins et al, 2017).…”

“…Furthermore, calix[n]arenes show several biological properties, such as antiviral (Motornaya, et al, 2006), anticancer (Dings et al, 2012;Pelizzaro-Rocha et al, 2013) and antimicrobials (Mourer et al, 2006;Lamartine et al, 2002). Recently, a new class of calixarene dimers made up of tetra(carboxymethoxy)calix [4]arenes (CX4A) and sodium ions, named as calix [4]tubes, has provided opportunities to load guests simultaneously into two annulus cavities (Martins et al, 2016). The partially deprotonated CX4A when coordinated to sodium ions is a neutral species, featuring a calixarene dimer stable even in solution (Martins et al, 2016).…”

“…Recently, a new class of calixarene dimers made up of tetra(carboxymethoxy)calix [4]arenes (CX4A) and sodium ions, named as calix [4]tubes, has provided opportunities to load guests simultaneously into two annulus cavities (Martins et al, 2016). The partially deprotonated CX4A when coordinated to sodium ions is a neutral species, featuring a calixarene dimer stable even in solution (Martins et al, 2016).…”