Parent Salt Research Articles

The Potential of Gadolinium Ascorbate Nanoparticles as a Safer Contrast Agent.

There have been health concerns raised against the use of gadolinium (Gd)-based magnetic resonance imaging contrast agents. The primary observation is that Gd ions are prone to leaking into the bloodstream, causing nephrogenic systemic fibrosis as one of the side effects. In addition, such leakage of the ions inhibits easy clearance from the body. Herein we propose that Gd-ascorbate nanoparticles could be one of the safer choices as they are rather stable in aqueous dispersion and they do not get affected by Zn or Fe ions in the medium. The magnetic properties of the ions are preserved in the nanoparticles, and particles when sufficiently small may be amenable to renal clearance from the human body. Thus, when an aqueous solution of Gd-acetate and ascorbic acid was left to evolve with time, a Gd-ascorbate complex was formed that led to the formation of nanoparticles with time. The sizes of the nanoparticles increased with time, and when the particles were sufficiently large, they precipitated out of the medium. In addition, smaller nanoparticles were consistently present at all times of observations. UV-vis, photoluminescence and FTIR spectroscopy, mass spectrometry, and transmission electron microscopy analyses confirmed the formation of nanoparticles of Gd-ascorbate complex. In addition, magnetic measurements confirmed the high relaxivity of the nanoparticles as compared to the parent salt, indicating the effectiveness of the nanoparticles as contrast agents. Density functional theory-based calculations of the molecular complex-based nanoparticles accounted for the experimental observations.

Experimental Study of the Thermal Decomposition Properties of Binary Imidazole Ionic Liquid Mixtures.

Ionic liquids (ILs) have a wide range of applications, owing to their negligible vapor pressure, high electrical conductivity, and low melting point. However, the thermal hazards of ILs and their mixtures are also non-negligible. In this study, the thermal hazards of various binary imidazolium ionic liquids (BIIL) mixtures were investigated. The effects of parent salt components and molar ratios on the thermal decomposition temperature (Td) and flashpoint temperature (Tf) are investigated. It is found that both Td and Tf increase as the proportion of highly thermally stable components in BIIL mixtures increases. Furthermore, the decomposition process of BIIL mixtures can be divided into two stages. For most molar ratios, the Tf of the BIIL mixtures is in the first stage of thermal decomposition. When the proportion of highly thermally stable components is relatively high, Tf is in the second stage of thermal decomposition. The flammability is attributed to the produced combustible gases during the thermal decomposition process. This work would be reasonably expected to provide some guidance for the safety design and application of IL mixtures for engineering.

Phase transition behaviour of hydrated Glauber’s salt based phase change materials and the effect of ionic salt additives: A molecular dynamics study

Melting behaviour of inorganic hydrated salts plays an important role in their application as phase change energy storage materials. Particularly, the phase transition temperature and latent heat are determining factors for their application in specific areas for building heating. Ionic salts (e.g. NaCl, KCl) have been proposed as additives to synthesize Glauber’s salt with desired phase change properties. However, melting behaviour of the hydrated salts as well as the role of additives is poorly understood, which limits our ability to synthesize these salts with targeted properties. In the present study, classical molecular dynamics simulations were used to study the melting behaviour of pure Glauber’s salt. System of NaCl.Na2SO4.10H2O was studied to gain insights into the atomistic mechanism of the ionic salt additives. It is observed that the transition of hydrated Glauber’s salt into anhydrous Na2SO4 happens over a temperature range due to the stepwise dissociation of water molecules from the parent salt molecule. Addition of NaCl results in lowering the phase transition temperature, while increasing the latent heat of phase change at the same time. Simulation results showed that the hydrogen bonding capacity and ionic charge of the additive salts are the determining factors in altering the phase transition behaviour of hydrated salts. Simulation results showed an excellent agreement with the experimental data available in the literature.

Investigation of Poor Solubility of a Salt-Cocrystal Hydrate: A Case Study of the Common-Ion Effect in Betrixaban, an Anticoagulant Drug.

Achieving the desired solubility and dissolution of active pharmaceutical ingredients (APIs) continues to be a big challenge in the pharmaceutical industry. In this regard, multicomponent solids of APIs such as salts and cocrystals have shown significant promise in resolving such solubility/dissolution issues. However, very little is known on how the APIs' solubility or dissolution is affected by the drug to coformer ratio in multicomponent solids. Betrixaban, is an anticoagulant drug approved in 2017 for the prevention of venous thromboembolism. During the alternate solid form development studies of the known betrixaban maleate, a rare multicomponent solid form, salt-cocrystal hydrate of betrixaban, was discovered and characterized thoroughly by spectroscopic, thermal, and X-ray crystallographic methods. Significantly, the new betrixaban maleate maleic acid hydrate (1:1:2:1) form has shown lower melting point (80 °C) as compared to its parent salt (197.5 °C). From such a large melting difference (117 °C) between the salt and salt-cocrystal hydrate of API, we anticipated substantially better solubility for the salt-cocrystal hydrate (low enthalpy). Furthermore, the predicted solubility also supported our anticipation. However, the powder dissolution tests at different pH conditions provided contrary results, that is, the salt-cocrystal hydrate showed 10 times lower solubility as compared to its salt. A detailed investigation, considering all the potential factors, revealed that "common-ion effect" could be a critical factor for the low solubility of the salt-cocrystal hydrate in which the API to coformer ratio is 1:3. To the best of our knowledge, this is the first case study on the solubility of pharmaceutical salt-cocrystal hydrates with an emphasis on "common-ion effect" or drug to coformer ratio.

Mechanistic Study of Selective Absorption of NO in Flue Gas Using EG-TBAB Deep Eutectic Solvents.

The selective absorption of NO in flue gas has been investigated using a series of deep eutectic solvents (DESs) as novel denitrifying agents. The EG-TBAB DESs used in this work are composed of a hydrogen donor ethylene glycol (EG) and a parent salt tetrabutylammonium bromide (TBAB). Effects of DES composition (EG:TBAB molar ratio), operation temperature, residence time, and O2 concentration in the flue gas on denitrification performances of EG-TBAB DESs have been investigated. The highest denitrification efficiency and capacity were achieved using EG to TBAB molar ratio of 50:1 at an operation temperature of 50 °C. The O2 partial pressure in the flue gas showed no noticeable effects on NO absorption in EG-TBAB DESs. EG-TBAB DESs maintain high denitrification stability after five absorption-desorption cycles. The calculated absorption equilibrium constant ( K0) and Henry's law constant ( H) showed that EG-TBAB DESs exhibited high absorption capacity for NO molecules, indicating that they are applicable in industrial denitrification processes. The kinetics analysis of NO absorption in EG-TBAB DESs indicated that EG-TBAB DESs could effectively absorb NO and the absorption of NO was strongly influenced by mass transfer.

New radical cation salt κ-(BETS)2Co0.13Mn0.87[N(CN)2]3 with two magnetic metals: Synthesis, structure, conductivity and magnetic peculiarities

A new metallic radical cation salt κ‐(BETS)2Co0.13Mn0.87[N(CN)2]3, where BETS is bis(ethylenedithio)tetraselenafulvalene, C10S4Se4H8, has been synthesized. In this salt, a part of Mn2+ ions are replaced by Co2+ which acts as a magnetic dopant with a different effective magnetic moment. Crystal structure, band structure, conducting and magnetic properties of the salt have been studied. Below 30K the material undergoes a metal-insulator transition, which is suppressed by applying a pressure of ∼0.5 kbar, leading to a superconducting ground state. While the structural and conducting properties are very similar to those of the parent salt κ‐(BETS)2Mn[N(CN)2]3, magnetic properties associated with localized moments in the anion layer are found to be surprisingly different.

Identification of the perchlorate parent salts at the Phoenix Mars landing site and possible implications

In 2008 the Phoenix Mars lander Wet Chemistry Laboratory (WCL) measured 0.6wt% of perchlorate (ClO4-) in the martian soil. A crucial question remaining unanswered is the identity of the parent salt phase(s) of the ClO4-. Due to the ClO4- ion’s high solubility and stability, its distribution, chemical forms, and interactions with water, could reveal much about the aqueous history of the planet. Until now, the presence of Ca(ClO4)2 as a parent salt has been considered unlikely because based on its eutectic point and model calculations, highly insoluble calcium carbonates and sulfates would serve as sinks for Ca2+ rather than Ca(ClO4)2. Thus, the dominant ClO4- parent salt has been assumed to be a hydrated form of Mg(ClO4)2. Here we report on the results of a new refined analysis of the Phoenix WCL sensor data, post-flight experiments run on a flight-spare WCL unit, and numerous laboratory analyses. The results show that the response of the Ca2+ sensor is extremely sensitive to the counter ion of the ClO4- salt, and that addition of martian soil to the Phoenix WCL that contained only Mg(ClO4)2 or Ca(ClO4)2 would have produced a very different response than what was observed on Mars. A series of analyses were run with Ca2+ sensors and calibration solutions identical to those used on Phoenix, and with a Mars simulant formulation known to give the same results as on Mars. The response of the Ca2+ sensor at various ratios of added Mg(ClO4)2 to Ca(ClO4)2 gave the best fit to the Phoenix data with a sample containing ∼60% Ca(ClO4)2 and 40% Mg(ClO4)2. These results suggest that the Ca(ClO4)2 in the Phoenix soil has not been in contact with liquid water and thus did not form by evaporation or sublimation processes. Had the highly soluble Ca(ClO4)2 come into contact with liquid water, then the presence of soluble sulfates would have, on evaporation formed only CaSO4. The presence of Ca(ClO4)2 and Mg(ClO4)2 phases at roughly the CaCO3 to MgCO3 ratio suggests that since their production, the ClO4- phases have remained in a severely arid environment, with minimal or no liquid water interaction. The formation of the Ca(ClO4)2 and Mg(ClO4)2 is also consistent with the interaction of atmospherically deposited HClO4 with Ca- and Mg-carbonates and may also contribute to CO2 enrichment of 18O and may contribute in explaining why carbonates on the surface are at much lower levels than expected from an earlier global wet and warm period.

Versatile and Nondestructive Photochemical Process for Biomolecule Immobilization

Covalent immobilization of unmodified biological materials as proteins has been performed through a one-step and soft method. This process is based on a polyazidophenylene layer derived from the electroreduction of the parent salt 4-azidobenzenediazonium tetrafluoborate on gold substrates. The wavelength used (365 nm) for the photochemical grafting of a large variety of molecules as biomolecules is a key point to this nondestructive immobilization method. This simple process is also versatile and could be used for covalently binding a wide range of molecules such as polyethylene glycol moieties, for example. To validate this approach for biochip or microarray fabrication, a surface plasmon resonance imaging (SPRi) platform for immobilization of various antibody families was created by grafting G-protein through this process. This SPRi antibodies platform was tested with several consecutive cycles of antigen injections/regeneration steps without loss of activity.

Amorphous/Crystalline (A/C) Thermodynamic “Rules of Thumb”: Estimating Standard Thermodynamic Data for Amorphous Materials Using Standard Data for Their Crystalline Counterparts

Standard thermochemical data (in the form of Δ(f)H° and Δ(f)G°) are available for crystalline (c) materials but rarely for their corresponding amorphous (a) counterparts. This paper establishes correlations between the sets of data for the two material forms (where known), which can then be used as a guideline for estimation of missing data. Accordingly, Δ(f)H°(a)/kJ mol(-1) ≈ 0.993Δ(f)H°(c)/kJ mol(-1) + 12.52 (R(2) = 0.9999; n = 50) and Δ(f)G°/kJ mol(-1) ≈ 0.988Δ(f)H°(c)/kJ mol(-1) + 0.70 (R(2) = 0.9999; n = 10). Much more tentatively, we propose that S°(298)(c)/J K(-1) mol(-1) ≈ 1.084S°(298)(c)/J K(-1) mol(-1) + 6.54 (R(2) = 0.9873; n = 11). An amorphous hydrate enthalpic version of the Difference Rule is also proposed (and tested) in the form [Δ(f)H°(M(p)X(q)·nH(2)O,a) - Δ(f)H°(M(p)X(q),a)]/kJ mol(-1) ≈ Θ(Hf)n ≈ -302.0n, where M(p)X(q)·nH(2)O represents an amorphous hydrate and M(p)X(q) the corresponding amorphous anhydrous parent salt.

Highly Hydrophilic Surfaces from Polyglycidol Grafts with Dual Antifouling and Specific Protein Recognition Properties

Homopolymer grafts from α-tert-butoxy-ω-vinylbenzyl-polyglycidol (PGL) were prepared on gold and stainless steel (SS) substrates modified by 4-benzoyl-phenyl (BP) moieties derived from the electroreduction of the parent salt 4-benzoyl benzene diazonium tetrafluoroborate. The grafted BP aryl groups efficiently served to surface-initiate photopolymerization (SIPP) of PGL. In similar conditions, SIPP of hydroxyethyl methacrylate (HEMA) permitted the production of PHEMA grafts as model surfaces. Water contact angles were found to be 66°, 15°, and 0° for SS-BP, SS-PHEMA, and SS-PPGL, respectively. The spontaneous spreading of water drops on SS-PPGL was invariably observed with 1.5 μL water drops. PPGL thus appears as a superhydrophilic polymer. Resistance to nonspecific adsorption of proteins of PPGL and PHEMA grafts on gold was evaluated by surface plasmon resonance (SPR) using antibovine serum albumin (anti-BSA). The results conclusively show that PPGL-grafts exhibit enhanced resistance to anti-BSA adsorption compared to the well-known hydrophilic PHEMA. PPGL grafts were further modified with BSA through the carbonyldiimidazole activation of the OH groups providing immunosensing surfaces. The so-prepared PPGL-grafted BSA hybrids specifically interacted with anti-BSA in PBS as compared to antimyoglobin. It is clear that the superhydrophilic character of PPGL grafts opens new avenues for biomedical applications where surfaces with dual functionality, namely, specific protein grafting together with resistance to biofouling, are required.

ChemInform Abstract: The Oxidative Dehydrogenation of Isobutyric Acid to Methacrylic Acid on Ion Exchange Modified 12-Heteropoly Oxometalates.

The oxidative dehydrogenation of isobutyric acid (IBA) to methacrylic acid (MAA) has been studied over a series of 12-heteropoly oxometalate catalysts. H3PMo12O40, Cs3PMo12O40. (NH4)3PMo12O40, and a series of catalysts prepared using an ion exchange modification that resulted in the formation of mixed cation composition salts (NH4+/Cs+) were studied to investigate the contribution of the cation in the IBA to MAA process. Whereas the product selectivities obtained with the parent acid and ammonium salt were similar, those obtained with the cesium salt were markedly different. Studies of the self exchanged salts provided insight into the role of protons in the process, while investigations of the Cs+/NH4+ ion exchanged materials indicated that the cation can participate directly in the IBA to MAA reaction. The formation of MAA and acetone appears to involve a common intermediate, whereas propene forms through a different route.

Thermal genesis, characterization, and electrical conductivity measurements of terbium oxide catalyst obtained from terbium acetate

In this paper, the preparation and characterization of crystalline terbium oxide via thermal decomposition of acetate precursor is reported. The decomposition pathway of the parent salt was followed using TGA, DTA, and in situ electrical conductivity in air and nitrogen atmospheres. The obtained results indicated that, thermal decomposition of terbium acetate proceeded with the loss of water molecules, in two steps, below 150 °C followed by decomposition in the temperature range of 300–550 °C, throughout different intermediates, to give Tb 4O 7 as a final product. The calcination products, obtained by heating the parent salt for 3 h in air at various temperatures, were characterized using IR, XRD, SEM, nitrogen adsorption, and electrical conductivity measurements. It was demonstrated that Tb 4O 7 represents the major phase for the samples calcined at 600–900 °C. The role of Tb 3+–Tb 4+ redox couple in enhancing the electrical conductivity of the calcination products was also discussed.

Preparation of nickel nanoparticles and their catalytic activity in the cracking of methane

Metallic nickel nanoparticles are excellent catalysts for the cracking of methane into carbon nanotubes and hydrogen. Decomposition of tetrahydrate nickel acetate proceeds readily in inert or hydrocarbon streams to produce metallic nickel agglomerates (average size of 10–80nm) at around 350°C. In the present study, this parent salt is thermally treated in methane streams in situ in a thermogravimetric analyzer (TGA), and weight changes corresponding to the carbon buildup in the metallic nickel particles are analyzed to provide some insight into the nickel-catalyzed cracking process. C to Ni atomic ratios (C∕Ni) estimated directly from TGA data provided a systematic approach to study the catalytic activity of the nickel nanoparticles. Methane cracking starts at temperatures as low as 400°C and continues efficiently until approximately 600°C. Between 600 and 660°C, methane decomposition momentarily breaks off, while presumably the catalytic system undergoes a self-reorganization. Cracking resumes at 660°C and continues slowly up to 950°C. The amount of carbon deposited in the 600–660°C interval shows a linear dependence with methane concentrations, with C∕Ni ratios ranging from 6 to 31. Transmission-electron microscopy images of the different C∕Ni residues collected at 660°C show, that during cracking, narrower carbon nanotubes are produced at elevated methane concentrations, suggesting dispersion of nickel nanoparticles.

Mechanism of thermal decomposition of cobalt acetate tetrahydrate

AbstractThe thermal decomposition of cobalt acetate tetrahydrate (Co(CH3COO)2 · 4H2O) has been studied via thermogravimetric (TG) analysis, in situ X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results of TG and XRD showed that the parent salt melted and then the dissolved crystalline water was vaporized in two steps. The dehydration process was followed by a major step concerning the decomposition of the acetate group, leading to basic acetate as an intermediate, which then produced CoO and Co in N2 and H2 atmosphere, respectively. Three decomposition intermediates Co(CH3COO)2 · 0.5H2O, Co(CH3COO)2, and Co(OH)(CH3COO) were presumed. In situ XRD experiments revealed that the intermediate basic acetate was poorly crystallized or even amorphous. Evolved gases analysis indicated that the volatile products of acetate decomposition were water vapor, acetic acid, ethylenone, acetone, and CO2. A detailed thermal decomposition mechanism of Co(CH3COO)2 · 4H2O was discussed.

Spectacular Breeding of Crystals on Silica Gel

During experiments with silicic acid sols blended with thiosulfate solutions, an interesting phenomenon was observed. Namely, after gelation of the systems and evaporation of excessive water at ambient temperature, the gels cracked and on their surface grasslike offsprings appeared, which continued to grow. A closer inspection of these species showed them to be sodium thiosulfate, slightly less hydrated than the parent salt (pentahydrate). A literature search for explanation of this phenomenon led the authors to a class of minerals known as antholytes, whose representative is a rare mineral chalcanthite, CuSO4•5H2O. Further experiments with CuSO4•5H2O, Cr2(SO4)3•18H2O, Al2(SO4)3•18H2O, NiSO4•7H2O, Na2SO4•10H2O, and (NH4)2SO4 gave similar results. With colorful salts, the ”antholytes“ differed in hydration degree and morphology of crystals as compared to those of the parent salts. These experiments are particularly recommendable for undergraduate students for demonstration of several reactions and phenomena such as preparation of silicic acids by ion-exchange from sodium metasilicate, sol–gel transition, aging of silica gels, preparation of antholytes, and demonstration of the labile nature of monosilicic and thiosulfuric acids.

Thermal decomposition of nickel acetate tetrahydrate: an integrated study by TGA, QMS and XPS techniques

The thermal decomposition of nickel carboxylates is a feasible route to synthesize metal nanoparticles suitable for catalytic purposes. The aim of this work is the characterization of the thermal decomposition course of nickel acetate tetrahydrate, Ni(CH 3COO) 2·4H 2O. A thermogravimetric (TGA) decomposition study carried out in three different atmospheres (air, helium and hydrogen) showed that the dehydration of the parent salt occurs between 118 and 137 °C. However, irrespective of the chosen atmosphere, the sample weight loss registered in this stage remains invariable, suggesting the formation of a an intermediate basic acetate with the formula 0.86Ni(CH 3COO) 2·0.14Ni(OH) 2. The dehydration step was followed at ca. 350 °C by the subsequent one-step major decomposition of the acetate group, producing NiO and Ni, in treatment atmospheres of air and hydrogen, respectively, but there was some indication of an additional step when the thermolysis was conducted in helium. The conclusions possible from thermal analysis were confirmed by monitoring evolved gases employing quadrupole mass spectrometry (QMS), and a set of reactions linked to the decomposition of the acetate group has been proposed to account for most of the gas products detected. X-ray photoelectron spectroscopy (XPS) was used to investigate the solid phases obtained during the thermal decomposition of the salt in He atmosphere.

Ionic hydrates, M(p)X(q).nH(2)O: lattice energy and standard enthalpy of formation estimation.

This paper is one of a series (see: Inorg. Chem. 1999, 38, 3609; J. Am. Chem. Soc. 2000, 122, 632; Inorg. Chem. 2002, 41, 2364) exploring simple approaches for the estimation of lattice energies of ionic materials, avoiding elaborate computation. Knowledge of lattice energy can lead, via thermochemical cycles, to the evaluation of the underlying thermodynamics involving the preparation and subsequent reactions of inorganic materials. A simple and easy to use equation for the estimation of the lattice energy of hydrate salts, U(POT)(M(p)X(q).nH(2)O) (and therefore for solvated salts, M(p)X(q).nS, in general), using either the density or volume of the hydrate, or of another hydrate, or of the parent anhydrous salt or the volumes of the individual ions, is derived from first principles. The equation effectively determines the hydrate lattice energy, U(POT)(M(p)X(q).nH(2)O), from a knowledge of the (estimated) lattice energy, U(POT)(M(p)X(q)), of the parent salt by the addition of ntheta(U) where theta(U)(H(2)O)/kJ mol(-1) = 54.3 and n is the number of water molecules. The average volume of the water molecule of hydration, V(m)(H(2)O)/nm(3) = 0.0245, has been determined from data on a large series of hydrates by plotting hydrate/parent salt volume differences against n. The enthalpy of incorporation of a gaseous water molecule into the structure of an ionic hydrate, [Delta(f)H degrees (M(p)X(q).nH(2)O,s) - Delta(f)H degrees (M(p)X(q),s) - nDelta(f)H degrees (H(2)O,g)], is shown to be a constant, -56.8 kJ (mol of H(2)O)(-1). The physical implications with regard to incorporation of the water into various types of solid-state structures are considered. Examples are given of the use of the derived hydrate lattice energy equation. Standard enthalpies of formation of a number of hydrates are thereby predicted.

Apparent Molar Volumes of Benzyltrimethylammonium Bromide and Its Homologs in Aqueous Solution at 15, 25, and 35°C

Apparent molar volumes at infinite dilution of benzyltrimethylammonium bromide and its butyl and hexyl homologs at 15, 25, and 35°C and of dibenzyldimethylammonium bromide at 25°C in aqueous solution were estimated from density measurements. The additivity rule for the contribution of the methylene groups to the apparent molar volumes was found to be obeyed within a broad range of homologs, which covers the parent salt and the dodecyldimethylbenzylammonium bromide. The volumetric contribution of the phenylene (–C6H4–) group was estimated to be 61 cm3-mol−1 at 25°C. A value of −16.9 ± 0.3 cm3-mol−1 was suggested for the volumetric contribution of the N+ fragment to the apparent molar volume of alkylbenzyldimethylammonium salts.

High-pressure synthesis of aliphatic polypyromellitimides via nylon-salt-type monomers composed of aliphatic diamines and pyromellitic acid diesters

Aliphatic polypyromellitimides having high crystallinity were synthesized by the high-pressure thermal polycondensation of the nylon-salt-type monomers XPME composed of aliphatic diamines and pyromellitic acid p-diethyl esters. The polymer-forming reactivity of the salt monomers XPME was comparable to that of the parent salt monomers XPMA obtained from aliphatic diamines and pyromellitic acid itself. In addition, both salt monomers based on pyromellitic acid m- and p-diethyl esters with dodecamethylenediamine had the same reactivity, giving the identical polyimide.

Organometallic cation-exchanged phyllosilicates:57Fe Mössbauer spectroscopic study of organoiron complexes on a low-iron montmorillonite

Variable-temperature 57Fe Mössbauer spectroscopy, thermogravimetry and powder X-ray diffraction have been used to study the cations tricarbonyl(η5–2,4-dimethylcyclohexadienyl)iron(1+) and tricarbonyl(η5–2-methoxycyclohexadienyl)iron(1+) as both the hexafluorophosphate salts (A1 and A2, respectively) and when cation-exchanged onto the interlamellar sites of Westone-L (W-L), a low-iron montmorillonite (denoted A1-W-L and A2-W-L, respectively). A combination of thermogravimetry, total carbon analysis and X-ray fluorescence analysis for iron indicated that 40% of the available exchange sites on W-L were occupied by the cyclohexadienyl cations. The isomer shift, δ, and quadrupole splitting, Δ, of both A1 (δ= 0.02 mm s–1; Δ= 1.56 mm s–1) and A2 (δ= 0.02 mm s–1; Δ= 1.47 mm s–1) were unaffected by incorporation of the cations into the interlamellar environment. The hexafluorophosphate salts, A1 and A2, exhibited similar Debye temperatures, θD, and recoilless fractions, f, of 160 ± 2 K and 0.61, respectively, indicating that both iron moities enjoyed the same amount of freedom in the parent salt. In contrast, the values of θD and f for A2-W-L (140 K and 0.54, respectively) were both higher than for A1-W-L (131 K and 0.49), indicating that A2 was held more tightly in the interlamellar environment than A1.