Solutions In Polar Solvents Research Articles

Minimal Coarse-Grained Models of Polar Solvent for Electrolytes: Stockmayer Versus Dumbbell.

This study explores the potential of the dumbbell solvent as a minimal model for understanding electrolyte solutions in polar solvents. Our investigation involves a comparative analysis of the dumbbell model and the Stockmayer model, focusing on ion solvation and ion-ion correlations. We examine electrolytes containing symmetric monovalent salts dissolved in polar solvents while varying the ion density and solvent polarity. Both models predict an augmented solvent coordination number around ions as the solvent polarity increases, with the dumbbell solvent displaying a more pronounced effect. Notably, radial distribution functions (RDFs) between solvent and ions yield differing trends; Stockmayer models exhibit a nonmonotonic relationship due to strong dipole-dipole interactions at higher polarity, while RDFs for ions and dumbbell solvents consistently rise. In response to increased solvent polarity, Stockmayer solvents within the ion's solvation shell undergo continuous dipole orientation shifts, whereas the dumbbell solvent predominantly adopts pointing-away dipole orientations, diminishing pointing-to orientations. This underscores the significance of the interplay between the solvent molecular orientation and dipole rotation. Both models qualitatively predict ion pairing and clustering behaviors across varying solvent dipole strengths and salt concentrations. The Stockmayer solvent generally provides stronger electrostatic screening than the dumbbell solvent due to its neglect of the coupling between molecular orientation and dipole rotation. What's more, at a high dipole moment regime, ion-ion correlations in Stockmayer solvent can become stronger with increasing dipole moment due to stronger solvent-solvent correlations. This study underscores the effectiveness of the dumbbell solvent model in systematically elucidating the fundamental principles governing electrolytes and offers potential applications in the rational design of electrolyte systems.

Electrical Conductivity and Association of 1-butyl-3-methylpyridinium bis{(trifluoromethyl)sulfonyl}amide in Some Polar Solvents

The influence of alternating current frequency in the determination of the electrical conductivity of ionic liquids’ (ILs) dilute solutions in polar solvents has been considered. The frequency ranges in which the influence of polarization processes on electrodes occur and ionic relaxation occurs in the bulk of the solution have been excluded from the results of the electrical conductivity measurements. The association constants for Ka ILs in polar solvents published in literature were analyzed. A discrepancy between the values of Ka was noted, which is associated with the use of different calculation equations for electrical conductivity and the insufficiently correct consideration of the frequency dependance of the measured resistance. Based on the measured values of the electrical conductivity of dilute solutions of 1-butyl-3-methylpyridinium bis{(trifluoromethyl)sulfonyl}amide ([Bmpy][NTf2]) in acetonitrile (AN), dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) in the 20--65 °C temperature range, the thermodynamic characteristics of the [Bmpy][NTf2] association were determined. The effect of temperature on the molar electrical conductivity of [Bmpy][NTf2] at infinite dilution λ0 and the association constant Ka have been considered. The Walden product (λ0η), where η is the viscosity of the solvent, was also analysed. It was shown that in AN, DMSO, and DMF, λ0η changes in different ways with increasing temperature; however, the value of λ0η/(εT) corrected for permittivity ε and absolute temperature T does not depend on the temperature and nature of the solvent. As the temperature rises, the electrical conductivity of the dilute solutions of [Bmpy][NTf2] increases in direct proportion to the ratio of the permittivity to dipole dielectric relaxation time of the solvent

Nanocrystal‐Enabled Perovskite Heterojunctions in Photovoltaic Applications and Beyond

AbstractHeterojunctions are used to tailor the properties of semiconductors in optoelectronic devices, yet for emerging devices composed of metal halide perovskites, fabricating perovskite/perovskite heterojunctions has proved challenging due to solvent incompatibilities and rapid homogenization due to ion migration. Recent studies have demonstrated various strategies for using perovskite nanocrystals as a component to fabricate perovskite/perovskite heterojunctions, either with a perovskite thin film or a second nanocrystal layer. Heterojunctions such as these can impart many advantages of both bulk and nanocrystalline perovskite morphologies. This perspective focuses on recent developments of solution‐processed perovskite heterojunctions for solar cells and novel optoelectronic devices, in particular, highlighting the demonstrated and potential advantages of nanocrystal‐enabled fabrication strategies. A central tenet of this perspective is that the synthesis and dispersion of perovskite nanocrystals in non‐polar organic solvents offers a key processing advantage over traditional perovskite precursor solutions in polar solvents since the former allows for layer‐by‐layer deposition without dissolving an underlying perovskite film or crystal. This processing advantage, coupled with nanocrystal size control and ligand chemistry, enables perovskite heterojunctions with highly tunable optical and electrical properties. Such heterojunctions may enable disruptive technological advances in broad classes of devices such as solar cells, photodetectors, sensors, and (in)coherent photon sources with tunable polarization.

Understanding Charge Dynamics in Dense Electronic Manifolds in Complex Environments.

Photoinduced charge transfer (CT) excited states and their relaxation mechanisms can be highly interdependent on the environment effects and the consequent changes in the electronic density. Providing a molecular interpretation of the ultrafast (subpicosecond) interplay between initial photoexcited states in such dense electronic manifolds in condensed phase is crucial for improving and understanding such phenomena. Real-time time-dependent density functional theory is here the method of choice to observe the charge density, explicitly propagated in an ultrafast time domain, along with all time-dependent properties that can be easily extracted from it. A designed protocol of analysis for real-time electronic dynamics to be applied to time evolving electronic density related properties to characterize both in time and in space CT dynamics in complex systems is here introduced and validated, proposing easy to be read cross-correlation maps. As case studies to test such tools, we present the photoinduced charge-transfer electronic dynamics of 5-benzyluracil, a mimic of nucleic acid/protein interactions, and the metal-to-ligand charge-transfer electronic dynamics in water solution of [Ru(dcbpy)2(NCS)2]4-, dcbpy = (4,4'-dicarboxy-2,2'-bipyridine), or "N34-", a dye sensitizer for solar cells. Electrostatic and explicit ab initio treatment of solvent molecules have been compared in the latter case, revealing the importance of the accurate modeling of mutual solute-solvent polarization on CT kinetics. We observed that explicit quantum mechanical treatment of solvent slowed down the charge carriers mobilities with respect to the gas-phase. When all water molecules were modeled instead as simpler embedded point charges, the electronic dynamics appeared enhanced, with a reduced hole-electron distance and higher mean velocities due to the close fixed charges and an artificially increased polarization effect. Such analysis tools and the presented case studies can help to unveil the influence of the electronic manifold, as well as of the finite temperature-induced structural distortions and the environment on the ultrafast charge motions.

Extract of Ellagitannins starting with Strawberries (Fragaria sp.) and Blackberries (Rubus sp.)

Abstract Characterize the content of phytochemical compounds present in samples of extracts of strawberry (Fragaria sp.) and blackberry (Rubus sp.). The extraction of said compounds was carried out with solutions of polar solvents, such as acetone, ethanol and methanol, using an experimental design with three factors: state of maturity, resting time and temperature. The characterization of these fruits is the beginning of the utilization mainly of ellagitannins to produce ellagic acid. Total phytochemical content was determined by spectrophotometric techniques, for phenolic content it was used Folin-Ciocalteu, for flavonoids it was determined with aluminium chloride, the antioxidant activity was evaluated by the methods of DPPH and ABTS+, the bactericidal effect of the extracts was shown for strains of E. coli and S. aureus. The determination of ellagitannins was performed by spectrometry. The influence of the state of maturity on the response variable was evaluated; it was observed that concentration of phytochemicals increases proportionally to maturity stage. The antioxidant activity was evaluated, determining that extracts obtained exhibit 94% - 95% inhibition. The determination of ellagitannins, finding that the highest concentration of ellagitannins was found in a state of green maturity, for strawberries as well as blackberries.

Functional group interaction profiles: a general treatment of solvent effects on non-covalent interactions.

Solvation has profound effects on the behaviour of supramolecular systems, but the effects can be difficult to predict even at a qualitative level. Functional group interaction profiles (FGIPs) provide a simple visual method for understanding how solvent affects the free energy contribution due to a single point interaction, such as a hydrogen bond, between two solute functional groups. A generalised theoretical approach has been developed, which allows calculation of FGIPs for any solvent or solvent mixture, and FGIPs for 300 different solvents have been produced, providing a comprehensive description of solvent effects on non-covalent chemistry. The free energy calculations have been validated using experimental measurements of association constants for hydrogen bonded complexes in multiple solvent mixtures. The calculated FGIPs provide good descriptions of the solvation of polar solutes, solvophobic interactions between non-polar solutes in polar solvents like water, and preferential solvation in solvent mixtures. Applications are explored of the use of FGIPs in drug design, for optimising receptor-ligand interactions, and in enantioselective catalysis for solvent selection to optimise selectivity.

Physical properties and the ability to disperse into different polar solvents of the new polyurethane–cellulose composites

Novel castor oil (CO)-based polyurethane composites which include polyethylene glycol (PEG) as a polyol and cellulose fillers were prepared. The purpose of this article was to render polyurethane composites that can be dispersed in polar solvents (ethyl alcohol, isopropyl alcohol, and water) using bio-based feedstocks such as CO and cellulose. The chemical structures of the polyurethanes and their cellulose composites were studied by Fourier transform infrared spectroscopy and nuclear magnetic resonance of protons. The atomic force microscopy results showed the surface topography of the cellulose–polyurethane composites matrix. The inclusion of cellulose has been found to improve the thermal stability of the materials and their ability to disperse into the studied polar solvents. Cellulose along with PEG plays an important role in increasing the degree of moisture within the polyurethane composite matrix. Thus, we obtained solutions in polar solvents of polyurethane–cellulose composites without the use of waterborne polyurethanes.

The Effect of pH on Fuel-Cell Catalyst-Layer Inks

Fuel cell catalyst layers are cast from inks containing a solvent, an ionomer, and catalyst particles. Though there are generally accepted material classes (water/alcohol mixtures for the solvent, perfluorosulfonic acid (PFSA) polymers, and Pt-alloy based catalyst particles supported on carbon), there are no standard ratios or metrics for ink formulation. As such, ink recipes have been highly empirical to date, with little understanding of the governing interactions controlling resultant properties and behavior. This study therefore aims to systematically investigate the effect of pH on ink aggregation and rheology. Solvent choice greatly influences the morphology of PFSAs in solution1-4, which in turn alters pH. Starting with a solvent-ionomer compositional matrix, solvent versus pH effects are decoupled. Using dynamic and electrophoretic light scattering, rheology, and direct visualization with cryo electron microscopy, particle-solvent-ionomer systems are then studied to understand aggregation, stability, and rheology under various pH conditions. AcknowledgementsThis work was mainly funded under the Fuel Cell Performance and Durability Consortium (FC PAD) funded by the Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U. S. Department of Energy under contract number DE-AC02-05CH11231. S.A.B also acknowledges support from National Science Foundation Graduate Research Fellowship under Grant No. DGE 1106400. References Welch, C.; Labouriau, A.; Hjelm, R.; Orler, B.; Johnston, C.; Kim, Y. S., Nafion in Dilute Solvent Systems: Dispersion or Solution? ACS Macro. Lett. 2012, 1 (12), 1403-1407.Ma, C.-H.; Yu, T. L.; Lin, H.-L.; Huang, Y.-T.; Chen, Y.-L.; Jeng, U. S.; Lai, Y.-H.; Sun, Y.-S., Morphology and properties of Nafion membranes prepared by solution casting. Polymer 2009, 50 (7), 1764-1777.Lee, S.-J.; Yu, T. L.; Lin, H.-L.; Liu, W.-H.; Lai, C.-L., Solution properties of nafion in methanol/water mixture solvent. Polymer 2004, 45 (8), 2853-2862.Gebel, G.; Loppinet, B., Colloidal structure of ionomer solutions in polar solvents. J. Mol. Struct. 1996, 383 (1), 43-49.

Linear response coupled cluster theory with the polarizable continuum model within the singles approximation for the solvent response.

We report the theory and the implementation of the linear response function of the coupled cluster (CC) with the single and double excitations method combined with the polarizable continuum model of solvation, where the correlation solvent response is approximated with the perturbation theory with energy and singles density (PTES) scheme. The singles name is derived from retaining only the contribution of the CC single excitation amplitudes to the correlation density. We compare the PTES working equations with those of the full-density (PTED) method. We then test the PTES scheme on the evaluation of excitation energies and transition dipoles of solvated molecules, as well as of the isotropic polarizability and specific rotation. Our results show a negligible difference between the PTED and PTES schemes, while the latter affords a significantly reduced computational cost. This scheme is general and can be applied to any solvation model that includes mutual solute-solvent polarization, including explicit models. Therefore, the PTES scheme is a competitive approach to compute response properties of solvated systems using CC methods.

Convergence of Computed Aqueous Absorption Spectra with Explicit Quantum Mechanical Solvent.

For reliable condensed phase simulations, an accurate model that includes both short- and long-range interactions is required. Short- and long-range interactions can be particularly strong in aqueous solution, where hydrogen-bonding may play a large role at short range and polarization may play a large role at long range. Although short-range solute-solvent interactions such as charge transfer, hydrogen bonding, and solute-solvent polarization can be taken into account with a quantum mechanical (QM) treatment of the solvent, it is unclear how much QM solvent is necessary to accurately model interactions with different solutes. In this work, we investigate the effect of explicit QM solvent on absorption spectra computed for a series of solutes with decreasing polarity. By adjusting the boundary between QM and classical molecular mechanical solvent to include up to 400 QM water molecules, convergence of the calculated absorption spectra with respect to the size of the QM region is achieved. We find that the rate of convergence does not correlate with solute polarity when excitation energies are calculated using time-dependent density functional theory with a range-separated hybrid functional, but it does correlate with solute polarity when using configuration interaction singles. We also find that larger basis sets converge the computed spectrum with fewer QM solvent molecules. To optimize the computational cost with respect to convergence, we test a mixed basis set with more basis functions for atoms of the chromophore and the solvent molecules that are nearest to it and fewer basis functions for the atoms of the remaining solvent molecules in the QM region. Our results show that using a mixed basis set is a potentially effective way to significantly lower the computational cost while reproducing the results computed with larger basis sets.

On the isomers of pyridine-4-carboxaldoxime and its nitrate salt, X-ray crystal structure and quantum chemical calculations

The reaction between nitric acid and pyridine-4-carboxaldoxime (P4A) afford the corresponding pyridinum nitrate salt (P4AN). Its X-ray structure is measured and compared with the related P4A salts. The DFT/B3LYP results showed that both the P4A and P4AN favored the Syn-I form which has the lowest energy among the other possible isomers. Transition state calculations predicted that the Syn-I form is the thermodynamically and kinetically most stable form. The X-ray solid state structure of the new nitrate salt (P4AN) indicated that the labile proton favored the N-atom of the pyridine ring. DFT studies showed that the same is true for its solution in polar solvents. In contrast, the pyridinium cation is not favored either in the gas phase or solution of P4AN in nonpolar solvent. In these cases, the proton favored to bond with one O-atom from the nitrate group. Second order interaction energies and Mayer bond order values revealed these results. The bond order of the NH bond is higher in polar solvents as well as at the experimental structure than either in the gas phase or non polar solvents. The topology parameters obtained from the atoms in molecules (AIM) analysis were used to describe the nature of the NH and OH bonds. The bond critical points (BCP) were found to be close to the H-atoms in case of stronger interaction.

Open-ended formulation of self-consistent field response theory with the polarizable continuum model for solvation.

The study of high-order absorption properties of molecules is a field of growing importance. Quantum-chemical studies can help design chromophores with desirable characteristics. Given that most experiments are performed in solution, it is important to devise a cost-effective strategy to include solvation effects in quantum-chemical studies of these properties. We here present an open-ended formulation of self-consistent field (SCF) response theory for a molecular solute coupled to a polarizable continuum model (PCM) description of the solvent. Our formulation relies on the open-ended, density matrix-based quasienergy formulation of SCF response theory of Thorvaldsen, et al., [J. Chem. Phys., 2008, 129, 214108] and the variational formulation of the PCM, as presented by Lipparini et al., [J. Chem. Phys., 2010, 133, 014106]. Within the PCM approach to solvation, the mutual solute-solvent polarization is represented by means of an apparent surface charge (ASC) spread over the molecular cavity defining the solute-solvent boundary. In the variational formulation, the ASC is an independent, variational degree of freedom. This allows us to formulate response theory for molecular solutes in the fixed-cavity approximation up to arbitrary order and with arbitrary perturbation operators. For electric dipole perturbations, pole and residue analyses of the response functions naturally lead to the identification of excitation energies and transition moments. We document the implementation of this approach in the Dalton program package using a recently developed open-ended response code and the PCMSolver libraries and present results for one-, two-, three-, four- and five-photon absorption processes of three small molecules in solution.

Solvation structure around ruthenium(II) tris(bipyridine) in lithium halide solutions.

The solvation of the ruthenium(II) tris(bipyridine) ion ([Ru(bpy)3]2+) is investigated with molecular dynamics simulations of lithium halide solutions in polar solvents. The anion distribution around the [Ru(bpy)3]2+ complex exhibits a strong solvent dependence. In aqueous solution, the iodide ion forms a solvent shared complex with [Ru(bpy)3]2+, but not in the other solvents. Between Cl– and [Ru(bpy)3]2+, the strong hydration of the chloride ion results in a solvent separated complex where more than one solvent molecule separates the anion from the metal center. Hence, tailored solvation properties in electrolytes is a route to influence ion-ion interactions and related electron transfer processes.

One-step synthesis of water-soluble hexagonal NaScF4:Yb/Er nanocrystals with intense red emission.

Water-soluble hexagonal NaScF4:Yb/Er nanocrystals have been directly synthesized via a facile one-step hydrothermal route. The as-prepared nanocrystals were monodisperse and could form stable colloidal solutions in polar solvents, such as water and ethanol. The novel NaScF4:Yb/Er nanocrystals exhibited intrinsic intense red upconversion emission, in contrast to other lanthanide-doped fluoride nanocrystals. Remarkably, the upconversion emission intensity was enhanced ∼6.8 times through the coating of an active-shell (containing Yb(3+)) surrounding the NaScF4:Yb/Er core nanocrystals, owing to surface passivation effect and efficient energy transfer from Yb(3+) ions in both the core and the shell to Er(3+) ions. These water-soluble hexagonal NaScF4:Yb/Er nanocrystals with intense red emission are ideal for a variety of in vitro and in vivo biological imaging applications.

Unsaturated Iridium(III) Complexes Supported by a Quinolato–Carboxylato ONO Pincer-Type Ligand: Synthesis, Reactivity, and Catalytic C–H Functionalization

The unsaturated σ,π-cyclooctenyl iridium(III) pincer compound [Ir(κ3-hqca)(1-κ-4,5-η-C8H13)] (1) has been prepared by the reaction of [Ir(cod)(CH3CN)2]BF4 with lithium 8-oxidoquinoline-2-carboxylate (Li2hqca) and obtained as two isomers derived from the relative disposition of the pincer and the σ,π-cyclooctenyl ligands. Compound 1 can be prepared as a single isomer by reaction of 8-hydroxyquinoline-2-carboxylic acid (H2hqca) with [Ir(μ-OMe)(cod)]2. Reaction of [Ir(μ-OH)(coe)2]2 with H2hqca gave the square-pyramidal iridum(III) complex [IrH(κ3-hqca)(coe)] (3). This compound exists as dinuclear assemblies [IrH(κ3-hqca)(coe)]2 in noncoordinating solvents and as the corresponding labile mononuclear solvates in more polar solvent solutions. The dimerization of 3 was established by 1H-DOSY NMR spectroscopy and an ESI+ mass spectrum and supported by DFT calculations. Reaction of 3 with pyridine gave the adduct [IrH(κ3-hqca)(coe)(py)] (4) and the bis-pyridine complexes [IrH(κ3-hqca)(R-py)2] (R = H (6), 2-Me (7))...

A comparison between state-specific and linear-response formalisms for the calculation of vertical electronic transition energy in solution with the CCSD-PCM method

The calculation of vertical electronic transition energies of molecular systems in solution with accurate quantum mechanical methods requires the use of approximate and yet reliable models to describe the effect of the solvent on the electronic structure of the solute. The polarizable continuum model (PCM) of solvation represents a computationally efficient way to describe this effect, especially when combined with coupled cluster (CC) methods. Two formalisms are available to compute transition energies within the PCM framework: State-Specific (SS) and Linear-Response (LR). The former provides a more complete account of the solute-solvent polarization in the excited states, while the latter is computationally very efficient (i.e., comparable to gas phase) and transition properties are well defined. In this work, I review the theory for the two formalisms within CC theory with a focus on their computational requirements, and present the first implementation of the LR-PCM formalism with the coupled cluster singles and doubles method (CCSD). Transition energies computed with LR- and SS-CCSD-PCM are presented, as well as a comparison between solvation models in the LR approach. The numerical results show that the two formalisms provide different absolute values of transition energy, but similar relative solvatochromic shifts (from nonpolar to polar solvents). The LR formalism may then be used to explore the solvent effect on multiple states and evaluate transition probabilities, while the SS formalism may be used to refine the description of specific states and for the exploration of excited state potential energy surfaces of solvated systems.

Spatial decomposition and assignment of infrared spectra of simple ions in water from mid-infrared to THz frequencies: Li+(aq) and F−(aq)

Ionic hydration is of fundamental relevance from chemical reactivity in aqueous solution to biomolecular function at physiological conditions. Vibrational spectroscopy belongs to the most widely used experimental methods in studies of solvation phenomena. There is, however, still limited molecular understanding as to how the vibrational response of solutions is modulated by the presence of solvation shells around solutes, i.e., by interfacial water. Liquid-state THz spectroscopy has been demonstrated to be able to detect even small solute-induced changes of the hydrogen bond dynamics at the solute-water interface. In many cases it reveals rather long-ranged dynamical correlations around solutes, involving many solvent molecules, that can be tackled theoretically by analyzing vibrational spectra in a distance-resolved manner. Here, several spatial decomposition schemes for infrared spectra are used to reveal the distinct distance- and frequency-dependent contributions of the solvation shells to the spectral response in aqueous solutions of Li(+) and F(-). The importance of an explicit representation of the solute's electronic structure for the proper description of solute-solvent polarization effects is demonstrated. The solvent's response to the presence of the solute is systematically disentangled and reveals important differences between the spectral responses due to intra- and intermolecular motion as probed in the mid- and far-infrared spectral windows, respectively.

Butyltin(IV) citrates and tartrates: Structural characterization and their interaction with nucleotides

Butyltin complexes with biologically important hydroxyacids, citric HOOCCH2C(OH)(COOH)CH2COOH (C6H8O7) acid and (2R,3R)-(+)-tartaric HOOCCH(OH)CH(OH)COOH (C4H6O6) acid: [Sn(C4H9)2(C6H6O7)] (1), [Sn(C4H9)3(C6H7O7)] (2), (phenH)2[Sn(C4H9)3(C6H5O7)] (3), [Sn(C4H9)2(C4H4O6)] (4), [Sn(C4H9)3(C4H5O6)] (5), (phenH)[Sn(C4H9)3(C4H4O6)] (6) and [{Sn(C4H9)3}2(C4H4O6)] (7) have been synthesized and characterized by ESI–MS, IR and 1H, 13C and 119Sn NMR spectra. Their structures and properties in solid state and solutions were proposed on the basis of the spectroscopic data and density functional theory (DFT) calculations at B3LYP/3-21G** level. Complexes in solutions in polar solvents are five-coordinate as evidenced by 13C and 119Sn NMR spectra. Geometries of the five-coordinate complexes were optimized with B3LYP/3-21G** calculations. The 13C, 31P and 119Sn NMR spectra prove that complexes effectively interact with AMP, ATP and DAMP nucleotides forming Sn–OP bonds and N⋯H–O (nucleotide–carboxylate ligand) hydrogen bonds. In the case of dibutyltin complexes (1 and 4) nucleotides may also be coordinated as a chelating ligands via phosphate group and N7 atom of adenine residue.

Facile and efficient one-pot solvothermal and microwave-assisted synthesis of stable colloidal solutions of MFe2O4 spinel magnetic nanoparticles

Well-defined synthesis conditions of high quality MFe2O4 (M = Mn, Fe, Co, Ni, Zn, and Cu) spinel ferrite magnetic nanoparticles, with diameters below 10 nm, have been described based on facile and efficient one-pot solvothermal or microwave-assisted heating procedures. Both methods are reproducible and scalable and allow forming concentrated stable colloidal solutions in polar solvents, but microwave-assisted heating allows reducing 15 times the required annealing time and leads to an enhanced monodispersity of the nanoparticles. Non-agglomerated nanoparticles dispersions have been achieved using a simple one-pot approach where a single compound, triethyleneglycol, behaves at the same time as solvent and capping ligand. A narrow nanoparticle size distribution and high quality crystallinity have been achieved through selected nucleation and growth conditions. High resolution transmission electron microscopy images and electron energy loss spectroscopy analysis confirm the expected structure and composition and show that similar crystal faceting has been formed in both synthetic approaches. The spinel nanoparticles behave as ferrimagnets with a high saturation magnetization and are superparamagnetic at room temperature. The influence of synthesis route on phase purity and unconventional magnetic properties is discussed in some particular cases such as CuFe2O4, CoFe2O4, and ZnFe2O4.

Rare-Earth-Doped Bifunctional Alkaline-Earth Metal Fluoride Nanocrystals via a Facile Microwave-Assisted Process

Rare-earth-doped magnetic-optic bifunctional alkaline-earth metal fluoride nanocrystals have been successfully synthesized via a facile microwave-assisted process. The as-prepared nanocrystals were monodisperse and could form stable colloidal solutions in polar solvents, such as water and ethanol. They show bright-green fluorescence emisson. Furthermore, Gd(3+)-doped ones exhibit paramagnetic behavior at room temperature and superparamagnetic behavior at 2 K.