Synthesis and stability of functionalized iron oxide nanoparticles using organophosphorus coupling agents

Mohapatra, Sasmita; Pramanik, Panchanan

doi:10.1016/j.colsurfa.2009.01.009

Cited by 90 publications

(67 citation statements)

References 28 publications

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“…Some researchers believe that phosphonates bind in a tridentate fashion 30 does not necessarily mean a degradation of magnetic properties 33,18 . PSNP and CSNP diameters are estimated as 10.9 and 11.5 nm, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…This paper demonstrates that a single ligand can contain a functional group for binding to the nanoparticle surface and an additional catalytically active sulfonic acid group facing outward into solution. This approach takes advantage of differences in the 30 binding affinity of magnetite for different functional groups. In this research, carboxylic/phosphonic acids attach to the magnetic particle and a sulfonic acid group extends away from the particle toward the surrounding solution.…”

Section: Introductionmentioning

confidence: 99%

“…As seen in Figure 8, PSNP conversion returned to over 40% for runs 15-17, indicating that the catalyst had not been deactivated. 30 At this time, it is not possible to eliminate the detachment of ligands as partially responsible for the lower conversion noted for recycle runs 5-13. The phosphonate-magnetite bond is expected to be quite strong, so we do not expect ligand loss from the monolayer.…”

mentioning

confidence: 99%

“…Control runs with no catalyst present showed no conversion. Sugar analysis was conducted using an HPLC RCM-Ca+2 monosaccharide column (300 × 7.8 mm; Phenomenex, Torrance, 30 CA) with a refractive index detector. The HPLC was calibrated to external standards for sucrose, glucose, fructose, and maltose, using 80°C deionized water at a flow rate of 0.6 mL/minute.…”

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confidence: 99%

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Acid monolayer functionalized iron oxide nanoparticles as catalysts for carbohydrate hydrolysis

et al. 2014

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Superparamagnetic iron oxide nanoparticles were functionalized with a quasi-monolayer of 11-sulfoundecanoic acid and 10-phosphono-1-decanesulfonic acid ligands to create separable solid acid catalysts. The ligands are bound through carboxylate or phosphonate bonds to the magnetite core. The ligand-core bonding surface is separated by a hydrocarbon linker from an outer surface with exposed sulfonic acid groups. The more tightly packed monolayer of the phosphonate ligand corresponded to a higher sulfonic acid loading by weight, a reduced agglomeration of particles, a greater tendency to remain suspended in solution in the presence of an external magnetic field, and a higher catalytic activity per sulfonic acid group. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), and dynamic light scattering (DLS). In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylicsulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. The activity of the acid-functionalized nanoparticles was compared to the traditional solid acid catalyst Amberlyst-15 for the hydrolysis of starch in aqueous solution. Catalytic activity for starch hydrolysis was in the order PSNPs > CSNPs > Amberlyst-15. Monolayer acid functionalization of iron oxides presents a novel strategy for the development of recyclable solid acid catalysts. † Electronic supplementary information (ESI) available: Complete reaction details for 10-phosphono-1-sulfonodecanic acid, and starch hydrolysis table. See

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Acid monolayer functionalized iron oxide nanoparticles as catalysts for carbohydrate hydrolysis

et al. 2014

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“…Surface functionalized iron oxide magnetic nanoparticles (MNPs) are a type of novel functional materials, which have been widely used in biotechnology and catalysis [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Magnetic particles can be coated with a protective layer of different materials to improve their stability and to introduce new surface properties and functionalities.…”

Section: Introductionmentioning

confidence: 99%

Starch as a green source for Fe3O4@carbon core–shell nanoparticles synthesis: a support for 12-tungstophosphoric acid, synthesis, characterization, and application as an efficient catalyst

Rafiee

Khodayari

2015

Res Chem Intermed

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12-Tungstophosphoric acid (PW) immobilized on carbon-coated Fe 3 O 4 nanoparticles (Fe 3 O 4 @C-PW) was prepared through a combination of hydrothermal and chemical co-precipitation. The intermediate carbon layer, which was produced from starch as a green material, protects the magnetic core and also improves the dispersion and catalytic activity of the nanoparticles. Characterization of this catalyst was investigated by high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry, and the acidic properties were studied by NH 3 -temperature programmed desorption and potentiometric titration. The HRTEM image showed that the catalyst had a well-defined core-shell structure with an average particle size of 50 nm. The characterization data derived from FT-IR reveal that basic structure and geometry of the Keggin anion are preserved after synthesis of Fe 3 O 4 @C-PW. The as-prepared Fe 3 O 4 @C-PW was used as a nanocatalyst for the synthesis of various bis(indolyl)methanes and b-functionalized indoles in water. The catalyst can be recovered simply using an external magnetic field and reused several times without appreciable loss of its catalytic activity.

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Tunable Composition of Mixed Self‐Assembled Shell‐by‐Shell Structures on Nanoparticle Surfaces

Eigen

Stiegler

Gradl

et al. 2022

Adv Materials Inter

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of the individual molecules has a decisive influence on the final properties of the resulting suprastructure. In micelles, this can be the size and shape, for vesicles, the diffusion speed through the molecular bilayer, or for self-assembled monolayers (SAMs) the packing density and crystallinity. [1][2][3][4] Properties of such assemblies can be either modified by tuning the individual molecules or by a smart combination of multiple building blocks. [5][6][7][8][9][10][11][12][13] This concept is proven by nature as a highly reliable method to create, for example, cell membranes, which consist of hundreds of different molecules, even for the simplest organisms resulting in remarkably high functionality. [14,15] Among many other tasks, those molecules control the stability, the salt content in cells, the oxygen and nutrient uptake, and the size of these structures. [15] The exact selection of molecule types and stoichiometric composition of membranes play a decisive role in the functioning of the cells. Most prominent examples are amphiphiles that consist of two parts of different polarities, thus making them soluble in orthogonal solvents.All corresponding suprastructures are based on weak hydrophobic interactions as well as intermolecular recognition motifs such as stereo complexation, H-bonding, ionic interactions, etc. [16] But even in simple artificial micelles and vesicles (compared to biological systems), competing forces between two or more molecules can either lead to synergetic effects or segregation of the involved molecules into multiple structures with heterogeneous composition. [17,18] In particular for the combination of highly orthogonal amphiphiles bearing fluorophilic and lipophilic (alkyl-chained) residues, there are only a few examples of synergetic mixtures known. [18,19] However, such orthogonally chained molecules tend to self-assemble to mixed SAMs if they exhibit strong covalent binding anchor groups such as phosphonic acids. The covalent binding drives the self-assembly on, for example, oxide surfaces and prevent the individual molecules from segregating into multiple phases, which allows the formation of SAMs in any stoichiometric mixing ratio. [20] Based on such SAMs, vesicle-like structures (see Scheme 1) can be formed with nanoparticles as template by building up a second layer through non-covalent interactions to a shell-by-shell (SbS) system. [21][22][23][24][25][26] Such unique systems provide the opportunity to switch the polarity of core-shell nanoparticles for adjusted processing, [21] to prepare model bilayers The formation of mixed shell-by-shell (SbS) systems with tunable shell compositions is demonstrated by using molecular self-assembly driven by chemical recognition motifs. Aluminum oxide nanoparticles (AlOx-NPs) act as template surface for a self-assembled monolayer (SAM) of either partially fluorinated fluoroalkyl or alkyl chained phosphonic acid derivatives or defined stoichiometric mixtures of those. By providing an equimolar mixture of corresponding fluoroalkyl and a...

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Synthesis and stability of functionalized iron oxide nanoparticles using organophosphorus coupling agents

Cited by 90 publications

References 28 publications

Acid monolayer functionalized iron oxide nanoparticles as catalysts for carbohydrate hydrolysis

Acid monolayer functionalized iron oxide nanoparticles as catalysts for carbohydrate hydrolysis

Starch as a green source for Fe3O4@carbon core–shell nanoparticles synthesis: a support for 12-tungstophosphoric acid, synthesis, characterization, and application as an efficient catalyst

Tunable Composition of Mixed Self‐Assembled Shell‐by‐Shell Structures on Nanoparticle Surfaces

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