Ligand Versatility in Supercrystal Formation

Reichhelm, Annett; Haubold, Danny; Eychmüller, Alexander

doi:10.1002/adfm.201700361

Cited by 30 publications

(32 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…emulated the proteome architecture of magnetotactic bacteria and used the polyamino acid poly- l -arginine (polyR) in the in vitro precipitation of magnetite, which resulted in colloidally stable, mesocrystalline nanoparticles of ∼40 nm diameter. The magnetic behavior of the mesocrystals surprisingly reflected that of the superstructure 18 rather than that of the building blocks, as reported earlier. 19…”

supporting

confidence: 77%

Shaping Magnetite with Poly-l-arginine and pH: From Small Single Crystals to Large Mesocrystals

Kuhrts

Macías‐Sánchez

Tarakina

et al. 2019

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

Control over particle size, size distribution, and colloidal stability are central aims in producing functional nanomaterials. Recently, biomimetic approaches have been successfully used to enhance control over properties in the synthesis of those materials. Magnetotactic bacteria produce protein-stabilized magnetite away from its thermodynamic equilibrium structure. Mimicking the bacteria’s proteins using poly-l-arginine we show that by simply increasing the pH, the dimensions of magnetite increase and a single- to mesocrystal transformation is induced. Using synchrotron X-ray diffraction and transmission electron microscopy, we show that magnetite nanoparticles with narrow size distributions and average diameters of 10 ± 2 nm for pH 9, 20 ± 2 nm for pH 10, and up to 40 ± 4 nm for pH 11 can be synthesized. We thus selectively produce superparamagnetic and stable single-domain particles merely by controlling the pH. Remarkably, while an increase in pH brings about a thermodynamically driven decrease in size for magnetite without additives, this dependency on pH is inverted when poly-l-arginine is present.

show abstract

supporting

confidence: 77%

Shaping Magnetite with Poly-l-arginine and pH: From Small Single Crystals to Large Mesocrystals

Kuhrts

Macías‐Sánchez

Tarakina

et al. 2019

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

show abstract

“…[3][4][5][6] Ligands and ligand-solvent interactions govern the kinetics of NC nucleation and growth, 6 determine the stability of nanocolloids, enable NC coatings 12 or patterns 13 to be formed, and regulate oriented attachment or self-assembly in higher order architectures, such as composite particles, aerogels, and superlattices. [14][15][16][17][18][19] Despite its tremendous importance, no direct method exists to measure ligand-solvent interaction. Since this interaction determines whether ligands are fully extended or bundled together, interparticle distances, measured via Transmission Electron Microscopy (TEM), have been used to infer the ligand shell thickness and have been correlated to superlattice formation dynamics.…”

Section: Introductionmentioning

confidence: 99%

Probing Solvent–Ligand Interactions in Colloidal Nanocrystals by the NMR Line Broadening

et al. 2018

View full text Add to dashboard Cite

Although solvent-ligand interactions play a major role in nanocrystal synthesis, dispersion formulation and assembly, there is currently no direct method to study this. Here we examine the broadening of 1 H NMR resonances associated with bound ligands, and turn this poorly understood descriptor into a tool to assess solvent-ligand interactions. We show that the line broadening has both a homogeneous and a heterogeneous component. The former is nanocrystal-size dependent and the latter results from solvent-ligand interactions. Our model is supported by experimental and theoretical evidence that correlates broad NMR lines with poor ligand solvation. This correlation is found across a wide range of solvents, extending from water to hexane, for both hydrophobic and hydrophilic ligand types, and for a multitude of oxide, sulfide and selenide nanocrystals. Our findings thus put forward NMR line shape analysis as an indispensable tool to form, investigate and manipulate nanocolloids.

show abstract

“…However, due to the complex interplay of physical and chemical processes that govern the self‐assembly it is difficult to predict and control the superstructure organization . Thus, nanoparticle assemblies involve a variety of interactions and driving forces between inorganic hard core, organic soft surface‐coating ligands, and surrounding solvent molecules . As a consequence, a thorough understanding of a solvent‐mediated assembly process is required to produce NC solids with programmable properties.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Nanocrystal Self‐Assembly in Real Time Using In Situ Small‐Angle X‐Ray Scattering

Lokteva

Koof

Walther

et al. 2019

Small

View full text Add to dashboard Cite

involve a variety of interactions and driving forces between inorganic hard core, organic soft surface-coating ligands, and surrounding solvent molecules. [2,[7][8][9] As a consequence, a thorough understanding of a solvent-mediated assembly process is required to produce NC solids with programmable properties.Here, we have chosen lead sulfide (PbS) nanocrystals as a model system for the investigation of the in situ self-assembly due to the possibility to produce monodisperse particles in a colloidal solution with a precisely controlled size. Additionally, the unique electronic properties of semiconductor PbS NCs with tunable bandgap make them attractive for many potential technological applications, including solar cells, light-emitting diodes, transistors, photodetectors, etc. [10][11][12][13] The structure and degree of order in NC superlattices depend on several factors, such as NC size and shape, ligand length, grafting density, ligand-solvent interactions, NC concentration, solvent evaporation rate (in case of evaporative assembly), and cell geometry or substrate where the assembly takes place. Thus, recent studies on lead chalcogenide NC assemblies revealed the formation of face-centered cubic (fcc) or body-centered cubic (bcc) superstructures as well as lattice distorted facecentered tetragonal (fct) and body-centered tetragonal (bct) superlattices. [14][15][16][17][18] However, their assembling mechanism remains largely unresolved mainly due to the challenge in measuring intermediate transitions between the initial colloidal state and the final superlattice state, especially in real time.Recently, in situ scattering methods have emerged as a powerful characterization tool to study the nucleation and growth of nanoparticle superlattices. [19][20][21][22] Small-angle X-ray scattering (SAXS) allows for monitoring the self-assembly dynamics with subsecond temporal resolution over large sample volumes under controlled conditions (e.g., controlled solvent vapor environment and temperature) and provides realtime information on long range order in the assembled structures. Often, the grazing-incidence small-angle X-ray scattering (GISAXS) technique is applied for in situ measurements, where a drop of nanocrystal suspension is placed on a substrate and evaporated in a controlled manner. [16,20,23,24] However, at small incident angles of the X-ray beam GISAXS is able to probe only up to several monolayers and is thus limited to the surface regime. For bulk measurements transmission SAXS is Self-assembled nanocrystal superlattices have attracted large scientific attention due to their potential technological applications. However, the nucleation and growth mechanisms of superlattice assemblies remain largely unresolved due to experimental difficulties to monitor intermediate states. Here, the self-assembly of colloidal PbS nanocrystals is studied in real time by a combination of controlled solvent evaporation from the bulk solution and in situ small-angle X-ray scattering (SAXS) in transmission geometry. For the fi...

show abstract

Ligand Versatility in Supercrystal Formation

Cited by 30 publications

References 80 publications

Shaping Magnetite with Poly-l-arginine and pH: From Small Single Crystals to Large Mesocrystals

Shaping Magnetite with Poly-l-arginine and pH: From Small Single Crystals to Large Mesocrystals

Probing Solvent–Ligand Interactions in Colloidal Nanocrystals by the NMR Line Broadening

Monitoring Nanocrystal Self‐Assembly in Real Time Using In Situ Small‐Angle X‐Ray Scattering

Contact Info

Product

Resources

About