Host-guest interactions of calix[4]resorcinarenes with benzene derivatives in conditions of reversed-phase high-performance liquid chromatography. Determination of stability constants

Abstract

Reversed‐phase high‐performance liquid chromatography [LiChrosorb RP‐18,UV detection at 254 nm and acetonitrile‐water (86:14,v/v) as mobile phase] was applied to studies of the host–guest complexation of tetraalkylcalix[4]resorcinareneoctols and their upper rim phosphoryl, sulfonyl and dialkylaminomethyl derivatives with some aromatic guests in the mobile phase. It was shown that the formation of the inclusion complexes results in changes in the retention of aromatic guests and improves their separation. Stability constants of the complexes were calculated from the dependences of the l/k′ values of the aromatic guest on the concentration of the calix[4]resorcinarene in the mobile phase. The molecular structure of 4,6,16,18‐tetrahydroxy‐10,12,22,24‐tetrakis(dipropoxyphosphoryloxy)‐2,8,14,20‐tetramethylcalix[4]resorcinarene (12) was determined. Crystal data for 12 are P21/n, a = 16.708(9) Å, b = 18.683(6) Å, c = 20.243(5) Å, β = 95.75(3)°, V = 6287(4) Å3 and Z = 4. Compound 12 exists in a boat conformation, in which two opposite unsubstituted resorcinol rings of the macrocyclic skeleton lie in the plane formed by four methine bridges and two diphosphorylated rings are perpendicular to the plane. © 1998 John Wiley & Sons, Ltd.

Energetics of Small Molecule and Water Complexation in Hydrophobic Calixarene Cavities

“…This stoichiometry is evident in solid-state complexes by X-ray crystallography 22,23 and solution NMR titrations, 13,24,25 but has been assumed, without rigorous demonstration, in functional materials involving calixarene selfassembled monolayers 26,27 and chromatographic stationary phases. 28,29 The data presented here verify that guests adsorb on grafted calixarene materials with a 1:1 stoichiometry and absolute enthalpies greater (more favorable) than those for guest condensation. This enhanced interaction reflects the cooperative effect of several phenolic groups within a single calixarene, but this interaction only introduces binding selectivity among various aromatic guests that arises from non-specific van der Waals interactions.…”

Methodologies for the Derivatization of Resorcin[4]arenes at the Upper Rim ortho‐Positions

“…Removal of the acylating groups resulted in formation of 3 in yields exceeding 70 %. The methodology could tolerate a variety of acylating, phosphorylating and sulfonating agents (Figure 3), [65][66][67][68] successfully forming the corresponding tetraacylated, tetraphosphorylated and tetrasulfonated resorcin [4]arene adducts, respectively. These were also demonstrated to undergo electrophilic aromatic substitution reactions with relative ease.…”

Recognition of amino acids by functionalized calixarenes

“…8 As such, complexation properties of calix[n]arenes functionalized with amino substrates like amines, amino acids and peptides, were studied in the crystalline state, in gas phase, and in solution by means of various techniques including: X-ray crystallography, NMR spectroscopy, high performance liquid chromatography, mass spectrometry, calorimetric or microcalorimetric and potentiometric titrations. [38][39][40][41][42][43][44] The MALDI mass spectrometry studies demonstrated that calix [6]arene derivatives form stronger complexes with amino acids in the gas-phase than calix [4]arenes. 40 Starting from calix [6]arenes with a cavity size adapted for the selective inclusion of small organic guests compared to calix [4]arenes, Jabin and Reinaud [45][46][47] synthesized a series of molecular receptors based on calix [6]arenes and developed some valuable strategies to obtain them in a well-defined rigid cone conformation in order to display such host-guest properties.…”