New Amphiphilic Imidazolium/Benzimidazolium Calix[4]arene Derivatives: Synthesis, Aggregation Behavior and Decoration of DPPC Vesicles for Suzuki Coupling in Aqueous Media

Abstract

In this study, new types of amphiphilic calix[4]arene derivatives bearing N-alkyl/aryl imidazolium/benzimidazolium fragments were designed and synthesized by two step transformation: Regioselective Blanc chloromethylation of distal-di-O-butyl calix[4]arene and subsequent interaction with N-Substituted imidazole/benzimidazole. Critical aggregation concentration (CAC) values were estimated using pyrene fluorescent probe. Obtained macrocycles were found to form submicron particles with electrokinetic potential +44–+57 mV in aqueous solution. For the first time it was found that amphiphilic calixarene causes the fast transformation of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) multilamellar vesicles into unilamellar ones and leads to the ordering of the lipid in membranes at the molar calixarene/DPPC ratio more than 0.07. In situ complexes of calixarene aggregates with Pd(OAc)2 were found to be active in Suzuki–Miyaura coupling of 1-bromo-4-nitrobenzene with phenylboronic acid in water. It was shown that bulky N-substituents of heterocycle decrease the catalytic activity of the aggregates. These result can be assigned to the inhibition effect of Pd(II) complex in situ formation by bulky substituents located on the aggregate surface. Embedding of the most active palladium N-heterocyclic carbene (NHC) complex with methylimidazolium headgroups into DPPC vesicles enhances its catalytic activity in Suzuki–Miyaura coupling.

New poly-imidazolium–triazole particles by CuAAC cross-linking of calix[4]arene bis-azide/alkyne amphiphiles – a prospective support for Pd in the Mizoroki–Heck reaction

“…1). The presence of cross peaks between protons of two neighboring benzene rings (d ¼ 7.31 and 7.04 ppm), cross peaks between protons of benzene rings with methylene protons of the imidazolium fragment, attached to neighboring benzene rings (d 20,22 and is a result of easy formation of p-quinone methide structures during ionization. 25 Aggregation behavior of 4, 5 and their mixture in aqueous solutions and their cross-linking using CuAAC…”

NHC Polymeric Particles Obtained by Self-Assembly and Click Approach of Calix[4]Arene Amphiphiles as Support for Catalytically Active Pd Nanoclusters

“…Hydrophobic and hydrophilic fragments, including those containing anchor groups for polymerization, can be easily introduced into their structure. The presence of imidazolium fragments, fixed on the macrocyclic platform, makes it possible to obtain catalytically active amphiphilic bis-NHC Pd(II) complexes, which we have shown earlier [19,20].…”

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles

“…The embedment of disubstituted imidazole derivative of calix [4]arene into DPPC liposomes was also carried out to accelerate Suzuki-Miyaura coupling of 1-bromo-4nitrobenzene with phenylboronic acid in water [129]. The entrapment of calixarene into multilamellar DPPC liposomes leads to their transformation into unilamellar ones, while the particle size before extrusion decreased from 600 ± 63 nm for pure DPPC vesicles to 60 ± 1 nm for calixarene-loaded liposomes at a calixarene-to-lipid molar ratio of 0.07.…”