Aggregation and complexation in a series of tetramethylenesulfonate-substituted calix[4]resorcinarenes

Abstract

NMR methods are employed to study the effects of inorganic salts, solvents, and guest molecules of methylviologen (MV 2+ ) and choline (Ch + ) on the aggregation properties of water soluble tetramethylene sulfonate substituted calix[4]resorcinarenes containing methyl (1), amyl (2), and heptyl (3) substituents in the lower rim. It is established that, in aqueous solutions at concentrations of 1-10 mM, compound 1 exists in the monomeric form; the size of aggregates of amphiphilic compound 2 gradually increases (aggregation number varies from 1 to 20); and hydrophobic compound 3 dissolves only in slightly alkaline aqueous solu tions to form large micellar aggregates. For macrocycles 2 and 3, which are inclined to aggregation, the aggre gate sizes depend on the concentration, pH, and ionic strength of solutions, as well as on the presence of organic solvents. Macrocycle 1 binds guest molecules Ch + and MV 2+ to yield inclusion complexes. In the presence of aggregates of substance 2, the binding of guest molecules is more efficient and they are encapsu lated between the rim of one molecule and the tail of another molecule of compound 2. The presence of guest molecules enhances the aggregation of macrocycle 2. In the case of compound 3 solutions, guest Ch + mole cules are predominantly localized in the hydrophobic environment of alkyl substituents of the host.

The effect of water in THF/water mixtures on CMC, aggregation sizes, and fluorescence quenching of a new calix[4]resorcinarene macrocycle

“…[26][27][28] Studies reveal a range of aggregate sizes (N agg ) for tetramethylene sulfonatesubstituted calix [4]resorcinarenes, demonstrating the influence of functionalization on self-assembly. 29 Functionalization plays a key role, with hydrogen bonding and metal coordination being the most common drivers. Vesicles, micelles, and nanoparticles are observed in water, while AFM studies revealed unexpected layered structures in amphiphilic calixarenes.…”

Host–Guest Interactions of Sodiumsulfonatomethyleneresorcinarene and Quaternary Ammonium Halides: An Experimental–Computational Analysis of the Guest Inclusion Properties

“…This amphiphilic behavior of tetrasulfonate derivatives (SR) has created new avenues for harnessing resorcinarenes in biological applications. 30,31 The representative examples of SRs studied in the literature include, methylenesulfonate groups appended at the upper-rim C2positions (Type-1), [30][31][32][33][34][35][36][37][38][39][40][41] sulfonate and phenolic oxygens linked by methylene chains (Type-2), 42 and alkylated sulfonate derivatives at the lower-rim (Type-3). [43][44][45] The nature of their binding to neutral, singly and doubly charged aliphatic/N-heterocycle cationic guests has been studied in solution to understand the sulfonate groups intricate role in H-G systems.…”