Cation exchange in synthetic manganates: II. The structure of an alkylammonium-saturated phyllomanganate

AbstractA synthetic phyllomanganate saturated with a series of primary alkylammonium cations has been examined using XRD, chemical analysis and X-ray photoelectron spectroscopy. A linear relationship exists between the basal spacing of the saturated alkylammonium-manganate and the hydrocarbon chain length in the interlayer, and from the gradient it is concluded that the alkyl chains are perpendicular to the manganate sheet. This orientation is a function of both the charge density and the presence of a layer of water molecules immediately adjacent to the manganate basal surfaces. Evacuation results in the loss of this interlayer water and the structure of the organo-manganate is considerably disrupted. The extent to which the interlayer arrangement can be reinstated by rehydration is dependent on the chain length of the saturating organo-cation. For cations of chain length > C6 the C contents suggest that cation in excess of the exchange capacity is present in the interlayer, but the absence of any compensating anion and the release of amine on evacuation suggests that the excess C arises from the presence of free amine.

Download Full-text

Structure and Interdigitation of Chain-Asymmetric Phosphatidylcholines and Milk Sphingomyelin in the Fluid Phase

Symmetry ◽

10.3390/sym13081441 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1441

Author(s):

Moritz P. K. Frewein ◽

Milka Doktorova ◽

Frederick A. Heberle ◽

Haden L. Scott ◽

Enrico F. Semeraro ◽

...

Keyword(s):

Chain Length ◽

Hydration Shell ◽

Fluid Phase ◽

Hydrocarbon Chain ◽

Specific Model ◽

Glycerol Backbone ◽

Membrane Composition ◽

Membrane Structures ◽

Hydrocarbon Chain Length ◽

Dynamics Simulations

We addressed the frequent occurrence of mixed-chain lipids in biological membranes and their impact on membrane structure by studying several chain-asymmetric phosphatidylcholines and the highly asymmetric milk sphingomyelin. Specifically, we report trans-membrane structures of the corresponding fluid lamellar phases using small-angle X-ray and neutron scattering, which were jointly analyzed in terms of a membrane composition-specific model, including a headgroup hydration shell. Focusing on terminal methyl groups at the bilayer center, we found a linear relation between hydrocarbon chain length mismatch and the methyl-overlap for phosphatidylcholines, and a non-negligible impact of the glycerol backbone-tilting, letting the sn1-chain penetrate deeper into the opposing leaflet by half a CH2 group. That is, penetration-depth differences due to the ester-linked hydrocarbons at the glycerol backbone, previously reported for gel phase structures, also extend to the more relevant physiological fluid phase, but are significantly reduced. Moreover, milk sphingomyelin was found to follow the same linear relationship suggesting a similar tilt of the sphingosine backbone. Complementarily performed molecular dynamics simulations revealed that there is always a part of the lipid tails bending back, even if there is a high interdigitation with the opposing chains. The extent of this back-bending was similar to that in chain symmetric bilayers. For both cases of adaptation to chain length mismatch, chain-asymmetry has a large impact on hydrocarbon chain ordering, inducing disorder in the longer of the two hydrocarbons.

Download Full-text

Evaluation of the Antimicrobial Protection of Pharmaceutical Kaolin and Talc Modified with Copper and Zinc

Materials ◽

10.3390/ma14051173 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1173

Author(s):

Fotini Martsouka ◽

Konstantinos Papagiannopoulos ◽

Sophia Hatziantoniou ◽

Martin Barlog ◽

Giorgos Lagiopoulos ◽

...

Keyword(s):

Cation Exchange ◽

Photoelectron Spectroscopy ◽

Antimicrobial Properties ◽

Exchange Capacity ◽

Elevated Concentration ◽

Chemical Mapping ◽

Exchange Method ◽

X Ray ◽

Copper And Zinc ◽

Antimicrobial Protection

Six pharmaceutical pastes were prepared using chemically modified kaolin and talc powders. Tests were conducted to determine their structural and chemical characteristics as well as their antimicrobial protection, thus rendering them suitable for cosmetic and pharmaceutical uses. Kaolin and talc were treated chemically via the cation exchange method to load the clay particles with copper and zinc ions, two cations well known for their antimicrobial properties. Mineralogical analyses were conducted by using X-ray diffraction (XRD) before and after the modification, confirming the mineralogical purity of the samples. Scanning electron microscopy was also used in conjunction with energy dispersed spectroscopy (SEM-EDS) to obtain chemical mapping images, revealing the dispersion of the added metals upon the clay minerals surfaces. Moreover, chemical analysis has been performed (XRF) to validate the enrichment of the clays with each metal utilizing the cation exchange capacity. All modified samples showed the expected elevated concentration in copper or zinc in comparison to their unmodified versions. From the X-ray photoelectron spectroscopy (XPS), the chemical state of the samples’ surfaces was investigated, revealing the presence of salt compounds and indicating the oxidation state of adsorbed metals. Finally, the resistance of pastes in microbial growth when challenged with bacteria, molds, and yeasts was assessed. The evaluation is based on the European Pharmacopeia (EP) criteria.

Download Full-text

Improvement of the thermal stability of dendritic silver-coated copper microparticles by surface modification based on molecular self-assembly

Nano Convergence ◽

10.1186/s40580-021-00265-8 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Tae Hyeong Kim ◽

Hyeji Kim ◽

Hyo Jun Jang ◽

Nara Lee ◽

Kwang Hyun Nam ◽

...

Keyword(s):

Thermal Stability ◽

Photoelectron Spectroscopy ◽

Self Assembly ◽

Electrically Conductive ◽

X Ray ◽

Alkyl Chains ◽

Conductive Film ◽

Initial Resistance ◽

Thermal Stability Of ◽

Scanning Electron

AbstractIn the study reported herein, silver-coated copper (Ag/Cu) powder was modified with alkanethiols featuring alkyl chains of different lengths, namely butyl, octyl, and dodecyl, to improve its thermal stability. The modification of the Ag/Cu powders with adsorbed alkanethiols was confirmed by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Each powder was combined with an epoxy resin to prepare an electrically conductive film. The results confirmed that the thermal stability of the films containing alkanethiol-modified Ag/Cu powders is superior to that of the film containing untreated Ag/Cu powder. The longer the alkyl group in the alkanethiol-modified Ag/Cu powder, the higher the initial resistance of the corresponding electrically conductive film and the lower the increase in resistance induced by heat treatment.

Download Full-text

Effect of Hydrocarbon Chain Length of Amphiphilic Ruthenium Dyes on Solid-State Dye-Sensitized Photovoltaics

Nano Letters ◽

10.1021/nl050555y ◽

2005 ◽

Vol 5 (7) ◽

pp. 1315-1320 ◽

Cited By ~ 127

Author(s):

Lukas Schmidt-Mende ◽

Jessica E. Kroeze ◽

James R. Durrant ◽

Md. K. Nazeeruddin ◽

Michael Grätzel

Keyword(s):

Solid State ◽

Chain Length ◽

Hydrocarbon Chain ◽

Dye Sensitized ◽

Hydrocarbon Chain Length ◽

Ruthenium Dyes

Download Full-text

Effect of primary amine hydrocarbon chain length for the selective catalytic reduction of NOx from diesel engine exhaust

Fuel ◽

10.1016/j.fuel.2010.02.015 ◽

2010 ◽

Vol 89 (9) ◽

pp. 2292-2298 ◽

Cited By ~ 9

Author(s):

Maria Stanciulescu ◽

Jean-Pierre Charland ◽

James F. Kelly

Keyword(s):

Diesel Engine ◽

Selective Catalytic Reduction ◽

Chain Length ◽

Primary Amine ◽

Catalytic Reduction ◽

Hydrocarbon Chain ◽

Engine Exhaust ◽

Diesel Engine Exhaust ◽

Hydrocarbon Chain Length ◽

Reduction Of Nox

Download Full-text

X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.3.2 ◽

2012 ◽

Vol 3 ◽

pp. 12-24 ◽

Cited By ~ 13

Author(s):

Hicham Hamoudi ◽

Ping Kao ◽

Alexei Nefedov ◽

David L Allara ◽

Michael Zharnikov

Keyword(s):

Chain Length ◽

Photoelectron Spectroscopy ◽

Self Assembled Monolayers ◽

Phenylene Ethynylene ◽

X Ray ◽

Molecular Length ◽

Assembled Monolayers ◽

Self Assembled ◽

Gold Thiolate

Self-assembled monolayers (SAMs) of nitrile-substituted oligo(phenylene ethynylene) thiols (NC-OPEn) with a variable chain length n (n ranging from one to three structural units) on Au(111) were studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and near-edge absorption fine-structure spectroscopy. The experimental data suggest that the NC-OPEn molecules form well-defined SAMs on Au(111), with all the molecules bound to the substrate through the gold–thiolate anchor and the nitrile tail groups located at the SAM–ambient interface. The packing density in these SAMs was found to be close to that of alkanethiolate monolayers on Au(111), independent of the chain length. Similar behavior was found for the molecular inclination, with an average tilt angle of ~33–36° for all the target systems. In contrast, the average twist of the OPEn backbone (planar conformation) was found to depend on the molecular length, being close to 45° for the films comprising the short OPE chains and ~53.5° for the long chains. Analysis of the data suggests that the attachment of the nitrile moiety, which served as a spectroscopic marker group, to the OPEn backbone did not significantly affect the molecular orientation in the SAMs.

Download Full-text

X-Ray Photoelectron Spectroscopy of Imidazolium Zwitterionic Salts: Comparison to Acetate Analogs and the Impact of the Alkyl Chain Length on the Charge Distribution

Journal of Applied Spectroscopy ◽

10.1007/s10812-017-0563-7 ◽

2017 ◽

Vol 84 (5) ◽

pp. 906-910 ◽

Cited By ~ 1

Author(s):

Sh. Men ◽

J. Jiang ◽

Y. Liu

Keyword(s):

Charge Distribution ◽

Chain Length ◽

Photoelectron Spectroscopy ◽

Alkyl Chain ◽

Alkyl Chain Length ◽

X Ray ◽

The Impact

Download Full-text

The Influence of Structure on Ba and K Uptake by a Synthetic Phyllomanganate

Clay Minerals ◽

10.1180/claymin.1994.029.2.07 ◽

1994 ◽

Vol 29 (2) ◽

pp. 215-222 ◽

Cited By ~ 7

Author(s):

E. Paterson ◽

R. Swaffield ◽

L. Clark

Keyword(s):

Chemical Analysis ◽

Cation Exchange ◽

Exchange Reaction ◽

Charge Distribution ◽

Photoelectron Spectroscopy ◽

Basal Spacing ◽

K Uptake ◽

Selective Uptake ◽

X Ray ◽

Bulk Chemical

AbstractThe uptake of Ba2+ and K+ by a synthetic Na-phyllomanganate has been studied by chemical analysis, X-ray diffractometry and X-ray photoelectron spectroscopy. The changes in basal spacing arising from cation exchange have been used to monitor the progress of the exchange reaction and confirm the selectivity measured by bulk chemical analysis. However, the selective uptake of Ba2+ over Ca2+ is much greater than that of K+ over Na+ and it is suggested that charge distribution in the interlayer is important. The results are discussed in the light of recent advances in our understanding of the phyllomanganate structure.

Download Full-text