Micelle nano-reactors as mediators of water-insoluble ligand complexation with Cu(II) ions in aqueous medium

Abstract

Complexation reactions between water-soluble and -insoluble reactants were shown to occur in aqueous media in the presence of normal or reverse surfactant micelles, in significantly higher yields at lower temperatures compared to those achieved in neat organic solvents. The highest yield enhancement in the complexation of novel water-insoluble bis(2-amino-1,3,4-thiadiazolyl)methane and 1,4-bis(2-amino-1,3,4-thiadiazolyl)benzene ligands with Cu(II) ions was achieved in the sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-heptane-water reverse micellar system at the hydration ratio of 15. The results revealed that AOT normal micelles cause a change in the reaction mechanism together with the enhancement of the complex formation. The observed micellar effects were rationalized on basis of the properties of bulk solvents, surfactants and ligands, considering the solvation and hydration ratios of reverse micelles. The results have proved the dependence of complex yield on the amount and accordingly also on the properties of water in the micellar core, indicating that the yield can be maximized by the optimization of the hydration ratio.

Effect of Block Length and Side Chain Length Ratios on Determining a Multicompartment Micelle Structure

“…Throughout recent decades of catalysis science, the development and potential applications of various implementations of immobilized catalysis have attracted no shortage of attention. − Of growing interest in more recent years is the possibility to harness the versatile morphologies of multicompartment micelles (MCMs) to create catalytic nanoreactors. − As is well known, the traditional micelle results from self-assembly of diblock co-polymers consisting of hydrophilic heads and hydrophobic tails in aqueous conditions. , The multicompartment micelle (MCM) likewise results from polymers of three (or more) mutually immiscible blocks, each with different solvophilicities, self-assembling in the solution into complex structures containing distinct regions or “compartments” of the species in the various co-polymer blocks. − …”

Structural Tunability of Multicompartment Micelles as a Function of Lipophilic–Fluorophilic Block Length Ratio

“…Common examples result from triblock copolymers containing hydrophilic, lipophilic, and fluorophilic blocks. − By introducing immobilized catalysts into MCM systems, it is possible to create a micelle nanoreactor . − Different catalysts may be attached to each block of the triblock copolymer; the immobilized catalysts are then confined to specific regions of the MCM. These distinct catalytic regions within the structure support simultaneous non-orthogonal reactions in the same chamber while still achieving high reaction rates and easy separability. − …”