| 1. |
- Agthe, Michael, et al.
(författare)
-
Following in Real Time the Two-Step Assembly of Nanoparticles into Mesocrystals in Levitating Drops
- 2016
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:11, s. 6838-6843
-
Tidskriftsartikel (refereegranskat)abstract
- Mesocrystals composed of crystallographically aligned nanocrystals are present in biominerals and assembled materials which show strongly directional properties of importance for mechanical protection and functional devices. Mesocrystals are commonly formed by complex biomineralization processes and can also be generated by assembly of anisotropic nanocrystals. Here, we follow the evaporation-induced assembly of maghemite nanocubes into mesocrystals in real time in levitating drops. Analysis of time-resolved small-angle X-ray scattering data and ex situ scanning electron microscopy together with interparticle potential calculations show that the substrate-free, particle-mediated crystallization process proceeds in two stages involving the formation and rapid transformation of a dense, structurally disordered phase into ordered mesocrystals. Controlling and tailoring the particle-mediated formation of mesocrystals could be utilized to assemble designed nanoparticles into new materials with unique functions.
|
|
| 2. |
- Aguilera Medina, Luis, 1983, et al.
(författare)
-
The effect of lithium salt doping on the nanostructure of ionic liquids
- 2015
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 17:40, s. 27082-27087
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we report on the evolution of the structure of two model ionic liquid families, N-alkyl-N-methylpyrrolidinium (Pyr1n-TFSI) and 1-alkyl-3-methylimidazolium (CnMIm-TFSI) (n = 3, 4, 6 and 8) both containing the bis(trifluoromethanesulfonyl)imide (TFSI) anion, upon the addition of LiTFSI using small angle X-ray scattering (SAXS). The introduction of a lithium salt (Li-salt) tunes the interactions through the substitution of the large cation in the ionic liquid with the small and charge localized lithium ion, thus increasing the coulombic contribution from ion-ion interactions. We find that the introduction of lithium ions results in a restructuring of the polar groups in the ionic liquids. These changes are manifested as an increase in the correlation lengths related to charge alternation of the ions and a more disordered structure. This restructuring is interpreted as a reconfiguration of the anions as they coordinate to the small and ionic lithium. In contrast, the length scale of the mesoscopic heterogeneities related to the clustering of alkyl chains is virtually unchanged with lithium doping. Moreover, the correlation corresponding to alkyl chain domains becomes more well defined with increasing salt concentration, suggesting that Li-salt doping, i.e. an increased columbic interaction in the system, promotes clustering of the alkyl tails.
|
|
| 3. |
- Burrell, Jamie, et al.
(författare)
-
Using Curvature Power to Map the Domain of Inverse Micellar Cubic Phases : The Case of Aliphatic Aldehydes in 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine
- 2017
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 33:44, s. 12804-12813
-
Tidskriftsartikel (refereegranskat)abstract
- Oxylipins, or fatty aldehydes, are a class of molecules produced from membrane lipids as a result of oxidative stress or enzyme-mediated peroxidation. Here we report the effects of two biologically important fatty aldehydes, trans,trans-2,4-decanedienal (DD) and cis-11-hexadecenal (HD), on the phase behavior of the lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) in water. We compare the phase behavior of DD/DOPE and HD/DOPE mixtures to the phase behavior of oleic acid/DOPE mixtures and show that DD, HD, and oleic acid have similar effects on the phase diagrams of DOPE. Notably, both DD and HD, like oleic acid, induce the formation of Fd3m inverse micellar cubic phases in DOPE/water mixtures. This is the first time that Fd3m phases in fatty aldehyde-containing mixtures have been reported. We assess the effects of DD, HD, and oleic acid on DOPE in terms of lipid spontaneous curvatures and propose a method to predict the formation of Fd3m phases from the curvature power of amphiphiles. This methodology predicts that Fd3m phases will become stable if the spontaneous curvature of a lipid mixture is -0.48 ± 0.05 nm-1 or less.
|
|
| 4. |
- Diaz-Gallifa, Pau, et al.
(författare)
-
Synthesis, Crystal Structure and Magnetic Characterization of a Series of Cu-II-Ln(III) Heterometallic [Ln = La, Ce, Pr, Nd and Sm) Metal-Organic Compounds with an Unusual Single Crystal to Single Crystal Phase Transition
- 2013
-
Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 13:11, s. 4735-4745
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis and structural characterization of five Cu(II)-Ln(III) heteronuclear metal-organic frameworks of formula {[Ln(4)Cu(4)(H2O)(26)(bta)(5)]center dot mH(2)O} and {[Ln(4)Cu(4)(H2O)(24)(bta)(5)]center dot pH(2)O} [Ln = La-III (1A/1B), Ce-III (2A/2B), Pr-III (3A/3B), Nd-III (4A/4B) and Sm-III (5A/5B) with m/p = 20 (1A)/16 (1B), 18 (2A)/16 (2B), 14 (3016 (3B), 22 (4A)/16 (4B) and 21 (5A)/14 (5B); H(4)bta =1,2,4,5-benzenetetracarboxylic acid (1-5)] have been performed. These compounds present a single-crystal to single-crystal phase transition from expanded A phases toward the B shrinking networks, which is triggered only in the presence of a dry environment. This phase transition is accompanied by a compression of the crystallographic b-axis in the range 2.4 to 2.8 angstrom with the consequent decrease of the unit cell volume from 9.5% to 12%. The isomorphous crystal structures of 1A-5A can be described as two crystallographically independent [Cu(II)-Ln(III)] heterometallic dinuclear units which are connected through two crystallographically independent bta(4-) ligands in the ac-plane, leading to 4,4-rectangular grids. These layers are connected along the crystallographic b-axis, through a pillaring bta(4-) group. The phase transition implies a change of the coordination mode of the bta4- pillar from bis-monodentate (1A-5A) to tetrakis-monodentate (1B-5B). Magnetic susceptibility measurements of polycrystalline samples of 1A-5A in the temperature range 2.0-300 K have in common the decrease of the chi T-M product with T which in the case of 1A is due to weak antiferromagnetic interactions between the copper(II) ions through the bta4- skeleton, the Lam cation being diamagnetic [J = -3.5 cm(-1) with the Hamiltonian defined H = -JS(Cu1)center dot S-Cu2,]. For the 2A-5A compounds, the additional exchange interaction between Cu-II and the paramagnetic Ln(II) is masked by the crystal field effects (which partially removes the 2J + 1 degeneracy of the L-2S+1(J) free-ion ground state in zero magnetic field) (2A-5A) and the thermal population of excited free-ion states (5A).
|
|
| 5. |
- Dymond, Marcus K., et al.
(författare)
-
Lipid Spontaneous Curvatures Estimated from Temperature-Dependent Changes in Inverse Hexagonal Phase Lattice Parameters : Effects of Metal Cations
- 2016
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:39, s. 10083-10092
-
Tidskriftsartikel (refereegranskat)abstract
- Recently we reported a method for estimating the spontaneous curvatures of lipids from temperature-dependent changes in the lattice parameter of inverse hexagonal liquid crystal phases of binary lipid mixtures. This method makes use of 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE) as a host lipid, which preferentially forms an inverse hexagonal phase to which a guest lipid of unknown spontaneous curvature is added. The lattice parameters of these binary lipid mixtures are determined by small-angle X-ray diffraction at a range of temperatures and the spontaneous curvature of the guest lipid is determined from these data. Here we report the use of this method on a wide range of lipids under different ionic conditions. We demonstrate that our method provides spontaneous curvature values for DOPE, cholesterol, and monoolein that are within the range of values reported in the literature. Anionic lipids 1,2-dioleoyl-sn-glycerol-3-phosphatidic acid (DOPA) and 1,2-dioleoyl-sn-glycerol-3-phosphoserine (DOPS) were found to exhibit spontaneous curvatures that depend on the concentration of divalent cations present in the mixtures. We show that the range of curvatures estimated experimentally for DOPA and DOPS can be explained by a series of equilibria arising from lipid-cation exchange reactions. Our data indicate a universal relationship between the spontaneous curvature of a lipid and the extent to which it affects the lattice parameter of the hexagonal phase of DOPE when it is part of a binary mixture. This universal relationship affords a rapid way of estimating the spontaneous curvatures of lipids that are expensive, only available in small amounts, or are of limited chemical stability.
|
|
| 6. |
- Ghazal, Aghiad, et al.
(författare)
-
Direct monitoring of calcium-triggered phase transitions in cubosomes using small-angle X-ray scattering combined with microfluidics
- 2016
-
Ingår i: Journal of Applied Crystallography. - 0021-8898. ; 49:6, s. 2005-2014
-
Tidskriftsartikel (refereegranskat)abstract
- This article introduces a simple microfluidic device that can be combined with synchrotron small-angle X-ray scattering (SAXS) for monitoring dynamic structural transitions. The microfluidic device is a thiol-ene-based system equipped with 125 μm-thick polystyrene windows, which are suitable for X-ray experiments. The device was prepared by soft lithography using elastomeric molds followed by a simple UV-initiated curing step to polymerize the chip material and simultaneously seal the device with the polystyrene windows. The microfluidic device was successfully used to explore the dynamics of the structural transitions of phytantriol/dioleoylphosphatidylglycerol-based cubosomes on exposure to a buffer containing calcium ions. The resulting SAXS data were resolved in the time frame between 0.5 and 5.5 s, and a calcium-triggered structural transition from an internal inverted-type cubic phase of symmetry Im3m to an internal inverted-type cubic phase of symmetry Pn3m was detected. The combination of microfluidics with X-ray techniques opens the door to the investigation of early dynamic structural transitions, which is not possible with conventional techniques such as glass flow cells. The combination of microfluidics with X-ray techniques can be used for investigating protein unfolding, for monitoring the formation of nanoparticles in real time, and for other biomedical and pharmaceutical investigations. A combination of microfluidics with X-ray techniques has been used to perform dynamic structural studies on nanoparticulate formulations.
|
|
| 7. |
- Ghazal, Aghiad, et al.
(författare)
-
Microfluidic Platform for the Continuous Production and Characterization of Multilamellar Vesicles : A Synchrotron Small-Angle X-ray Scattering (SAXS) Study
- 2017
-
Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 8:1, s. 73-79
-
Tidskriftsartikel (refereegranskat)abstract
- A microfluidic platform combined with synchrotron small-angle X-ray scattering (SAXS) was used for monitoring the continuous production of multilamellar vesicles (MLVs). Their production was fast and started to evolve within less than 0.43 s of contact between the lipids and the aqueous phase. To obtain nanoparticles with a narrow size distribution, it was important to use a modified hydrodynamic flow focusing (HFF) microfluidic device with narrower microchannels than those normally used for SAXS experiments. Monodispersed MLVs as small as 160 nm in size, with a polydispersity index (PDI) of approximately 0.15 were achieved. The nanoparticles produced were smaller and had a narrower size distribution than those obtained via conventional bulk mixing methods. This microfluidic platform therefore has a great potential for the continuous production of monodispersed NPs.
|
|
| 8. |
- Gomez, German E., et al.
(författare)
-
Two Sets of Metal Organic Frameworks along the Lanthanide Series Constructed by 2,3-Dimethylsuccinate: Structures, Topologies, and Strong Emission without Ligand Sensitization
- 2013
-
Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 13:12, s. 5249-5260
-
Tidskriftsartikel (refereegranskat)abstract
- Reactions in aqueous solution under hydrothermal conditions between (+/-)-2,3-dimethylsuccinic acid and lanthanide chlorides lead to two different isostructural types with chemical formulas [Ln(2)(C6H8O4)(3)(H2O)(2)] Ln(III) = Pr-Eu (except Pm) (Type I, compounds 1-4) and [Ln(2)(C6H8O4)(3)] Ln(III) = Tb-Yb (except Tm) (Type II, compounds 5-9). The crystal structure has been solved for the Pr (1)-, Sm (3)-, and Ho (7)-containing compounds by means of single-crystal XRD methods, whereas powder XRD Rietveld refinement was used for the rest of the MOFs. Compounds 1-4 crystallize in the triclinic space group P (1) over bar, whereas compounds 5-9 belong to the tetragonal space group P(4)2(1)2. Type I and II compounds are 3D frameworks consisting of chains of [LnO(8)(H2O)] or [LnO(8)] polyhedra, respectively, linked by dimethylsuccinate anions, giving rise to (IO2)-O-1 connectivity. All the compounds were characterized by X-ray diffraction, variable-temperature Fourier transform infrared spectroscopy, and thermal analysis. An exhaustive topological study was performed in comparison with other related compounds. The photoluminescent (PL) properties for compounds 3, 4, and 5 have been also explored, indicating that a metal-centered luminescent process takes place.
|
|
| 9. |
- Labrador, Ana, et al.
(författare)
-
The yellow mini-hutch for SAXS experiments at MAX IV Laboratory
- 2013
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 425:Part 7, s. 1-4
-
Tidskriftsartikel (refereegranskat)abstract
- I911-SAXS is the new SAXS (Small-Angle-X-ray-Scattering) beamline at the MAX IV Laboratory in Lund, Sweden. It is one of the 5 stations of the hard X-ray Cassiopeia beamline (I911) at the 1.5 GeV ring MAX II. I911-4 was converted into a multipurpose SAXS station which opened to the scientific community in May 2011. The SAXS users community at this laboratory comes from diverse fields of research with different needs and requirements at the end-station. This results in different set-ups routinely being installed in the easy-accessible experimental mini-hutch. The beam can be focused at sample-to-detector distances between a few hundred millimeters and more than two meters. This versatility permits a selection of q-ranges between 0.006 1/Å and 2 1/Å. The recent acquisition of a fast readout, low noise pixel detector (PILATUS 1M) and the implementation of a high-throughput solution SAXS are the latest beamline upgrades.
|
|
| 10. |
- Lundin, Filippa, 1992, et al.
(författare)
-
Structure and dynamics of highly concentrated LiTFSI/acetonitrile electrolytes
- 2021
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 23:25, s. 13819-13826
-
Tidskriftsartikel (refereegranskat)abstract
- High salt concentration has been shown to induce increased electrochemical stability in organic solvent-based electrolytes. Accompanying the change in bulk properties is a structural ordering on mesoscopic length scales and changes in the ion transport mechanism have also been suggested. Here we investigate the local structure and dynamics in highly concentrated acetonitrile electrolytes as a function of salt concentration. Already at low concentrations ordering on microscopic length scales in the electrolytes is revealed by small angle X-ray scattering, as a result of correlations of Li+ coordinating clusters. For higher salt concentrations a charge alternation-like ordering is found as anions start to take part in the solvation. Results from quasi-elastic neutron spectroscopy reveal a jump diffusion dynamical process with jump lengths virtually independent of both temperature and Li-salt concentration. The jump can be envisaged as dissociation of a solvent molecule or anion from a particular Li+ solvation structure. The residence time, 50-800 ps, between the jumps is found to be highly temperature and Li-salt concentration dependent, with shorter residence times for higher temperature and lower concentrations. The increased residence time at high Li-salt concentration can be attributed to changes in the interaction of the solvation shell as a larger fraction of TFSI anions take part in the solvation, forming more stable solvation shells.
|
|
