Iron Oxide Surface Chemistry: Effect of Chemical Structure on Binding in Benzoic Acid and Catechol Derivatives

Abstract

The excellent performance of functionalized iron oxide nanoparticles (IONPs) in nanomaterial and biomedical applications often relies on achieving the attachment of ligands to the iron oxide surface both in sufficient number and with proper orientation. Toward this end, we determine relationships between the ligand chemical structure and surface binding on magnetic IONPs for a series of related benzoic acid and catechol derivatives. Ligand exchange was used to introduce the model ligands, and the resultant nanoparticles were characterized using Fourier transform infrared-attenuated internal reflectance spectroscopy, transmission electron microscopy, and nanoparticle solubility behavior. An in-depth analysis of ligand electronic effects and reaction conditions reveals that the nature of ligand binding does not solely depend on the presence of functional groups known to bind to IONPs. The structure of the resultant ligand-surface complex was primarily influenced by the relative positioning of hydroxyl and carboxylic acid groups within the ligand and whether or not HCl(aq) was added to the ligand-exchange reaction. Overall, this study will help guide future ligand-design and ligand-exchange strategies toward realizing truly custom-built IONPs.

Advances in Magnetic Nanoparticles for Biomedical Applications

“…In addition to the intrinsic magnetic properties, these NPs can serve as centers of multiple coordination and hence exhibit localized increased functionality ( Figure ). Nevertheless, the excellent performance of magnetic NPs in nanomaterial and biomedical applications often relies on achieving the attachment of suitable polyphenolic ligands to the nanoparticle surface both in sufficient numbers and with proper orientation . The nature of ligand binding does not only solely depend on the presence of suitable functional groups, but also on relative positioning of these groups within the ligand and dynamics of ligand exchange on the nanoparticle surface.…”

Polydopamine Nanomembranes as Adhesion Layers for Improved Corrosion Resistance in Low Carbon Steel

“…Increasing the number of deposition cycles increases the size of the islands and clusters, improves uniformity, and increases the overall areal coverage. Dendritic cracks are observed in PDA coatings on Fe substrates, which could be attributed to either the underlying substrate or shrinking of PDA during sample preparation . According to EDS results (Figure b), the areal density of elements in organic PDA films (C, N) increases gradually with the number of coating cycles, while that of Fe is relatively stable (Table S3).…”

Antimicrobial activity of silver nanoparticles supported by magnetite

“…Two synthetic steps for the preparation of Fe 3 O 4 /5‐ASA/Ag composite can be recognized, the first, functionalization of Fe 3 O 4 NPs with 5‐ASA, and, the second, consequent reduction of Ag + ions to metallic silver. It is well‐established in the literature that the functionalization of metal‐oxide particles with salicylate‐type of ligands (aromatic compounds with adjacent hydroxyl and carboxyl groups) takes place by the condensation reaction between surface hydroxyl groups of metal‐oxide and functional groups of neighboring functional groups of organic molecules ,. The reactive amino group remains free upon surface‐modification of Fe 3 O 4 NPs with 5‐ASA.…”

“…Binding of salicylate‐type of ligands (salicylic acid derivatives) has been studied for a variety of oxide materials, such as TiO 2 , alumina, hydroxyapatite and Mg 2 TiO 4 . Surface complexes (sorption) between benzene derivatives and different iron oxides − goethite (α‐FeOOH), hematite (Fe 2 O 3 ), and magnetite (Fe 3 O 4 ), − have been primarily studied by infrared spectroscopy. Very instructive is the recent study by Blum et al .…”

“…Surface complexes (sorption) between benzene derivatives and different iron oxides − goethite (α‐FeOOH), hematite (Fe 2 O 3 ), and magnetite (Fe 3 O 4 ), − have been primarily studied by infrared spectroscopy. Very instructive is the recent study by Blum et al . concerning the binding of benzoic acid and catechol derivatives to the surface of magnetite.…”