Solid state interaction of steroids with calixarenes. I. A preliminary FTIR and DSC study on 4-en-3-keto-steroids

Encapsulation of Drug Molecules into Calix[n]arene Nanobaskets. Role of Aminocalix[n]arenes in Biopharmaceutical Field

“…Parini and coworkers were the first to study drug–CA complexes. In particular, the guest–host interaction between steroids and the hydrophobic para‐tert ‐butylcalix[ n ]arenes 120–122 was analyzed (see Table ).…”

Steroids in Molecular Recognition

“…While the cyclodextrins are known to rather unspecifically complex a broad range of apolar substrates including steroids (section III), the first artificial hosts for steroids were only reported some 10 years ago. Since then, a very limited number of novel synthetic steroid receptors have appeared in the literature. − Except for some steroid-recognizing polymers , obtained by molecular imprinting, so far all artificial receptors have been based on cyclophanes ,− (including calixarenes − ), a major class of macrocyclic hosts comprising bridged aromatic systems. Thereby, a few macrocycles have been shown to recognize polar steroids by means of multiple H-bonding in both apolar organic solvents 214-216 and in the solid state, while the others bind in aqueous or alcoholic solutions, − taking advantage of hydrophobic desolvation and dispersion forces besides electrostatic donor−acceptor interactions. − …”

“…Parini et al found evidence for calixarene−steroid complex formation in the solid state, based on both time-dependent Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) . Upon grinding mixtures of different Δ 4 -3-ketosteroids with p -( tert -butyl)[6]- and p -( tert -butyl)[8]calixarene, the crystal structure of the guests apparently breaks up.…”

para-Acylcalix[n]arenes: from molecular to macroscopic assemblies

“…2 Their use is facilitated by the two divergent chemistries, at the para-aromatic positions and at the phenolic hydroxylic groups not requiring protection-deprotection methodologies for selective chemical modification (Scheme 1). 3 This ease of chemical modification has allowed the calix-[n]arenes to serve as molecular platforms for the construction of receptors of gases, 4 both cations 5 and anions, 6 small organic molecules, 7 molecules of biological interest ranging from amino-acids 8 and peptides 9 through nucleotides, 10 steroids 11 to DNA 12 and proteins, 13,14 with such complexation being achieved in the gaseous, 15 solution 16 and solid-states. 17 The calix[n]arenes have seen applications in material science, both for the construction of molecular edifices, and as sensors, 14 selective filters at interfaces, 18 non-linear optical materials, 19 thin films, 20 and for gas storage.…”