A Supramolecular Catalyst Self-Assembled From Polyoxometalates and Cationic Pillar[5]arenes for the Room Temperature Oxidation of Aldehydes

Abstract

Oxidizing aldehydes to generate carboxylic acids is a crucial reaction in nature and in chemical industry. The aldehyde oxidation, an easily achieved process in liver cells, is inert toward autoxidation in industrial production and difficultly achieved under enzymatic condition (in water, at pH 7, at room temperature). Herein, we prepared a supramolecular catalyst which are nanospheres assembled in aqueous media by chromium centered Anderson polyoxometalates Na3[CrMo6O18(OH)3] (namely, CrMo6) and cationic pillar[5]arenes (namely, P5A) with 10 positive charges which can be used as the phase transfer catalysts (PTCs). This supramolecular catalyst was exploited on aldehydes oxidation under enzymatic condition with relatively good conversion. Through DLS monitoring, the diameters of nanospheres were variable while changing the charge ratios of the ionic complexes (P5A-CrMo6), and it is probably because of the closer charge ratios causing the more compact assemblies. Also, the nano-morphologies were monitored by TEM and SEM, and the nanostructures were characterized by zeta potential, the X-ray energy-dispersive spectroscopy (EDS), elemental analysis.

Nanoparticles based on the zwitterionic pillar[5]arene and Ag+: synthesis, self-assembly and cytotoxicity in the human lung cancer cell line A549

“…Thus, the analysis of experimental data indicates that Ag + cation is located outside of the macrocycle 3, between the aromatic ring and substituent fragments, forming supramolecular structures that do not contain a Ag-Ag bond. This hypothesis is in good agreement with the literature data [40,41]. The formation of the 3/Ag + associate was additionally confirmed by two-dimensional DOSY NMR spectroscopy.…”

Guest Controlled Pillar[5]arene and Polyoxometalate Based Two-Dimensional Nanostructures toward Reversible Iodine Capture

“…P5A and POM self-assemble into nanospheres, which we have reported recently. 54 While SDS was added, the system turned turbid obviously. When 1 ≤ SDS:P5A ≤ 6, the transmittance of this system evidently decreased.…”

Self-Assembled Supramolecular Polyoxometalate Hybrid Architecture as a Multifunctional Oxidation Catalyst

“…Among the different approaches to overcoming these problems, the construction of supramolecular nanoreactors proves to be very promising . Cyclodextrins (CDs) are cyclic oligosaccharides with cylindrical cone-shaped cavities as well-known supramolecular hosts. − Such a structure is endowed with a lipophilic inner surface and a hydrophilic outer surface, allowing one to include a wide range of organic molecules inside their cavities to form inclusion complexes. Thus, they can transfer hydrophobic molecules from the organic phase to the catalytic species in aqueous media as inverse phase transfer agents for aqueous biphasic reactions, giving rise to the enhanced solubility of organic substrates in water.…”