Ether-type Solvents Research Articles

Solvent racing crystallization: Low-solvation dispersion cosolvents for high-quality halide perovskites in photovoltaics

•Designing dispersion cosolvents with reduced solvation capacity •Utilizing solvent polarity and hydrogen-bonding property to their advantage •Promoting the growth of perovskite films with preferred orientation •Attaining solar module (18 cm2 active area) with an efficiency exceeding 22% The solvation capacity of dispersion solvents plays a crucial role in the solution processing of metal halide perovskites. For instance, N,N-dimethylformamide (DMF), a widely used dispersion solvent, possesses high solvation capacity but often generates suboptimal film quality due to slow crystallization kinetics. We propose using low-solvation binary cosolvents (nitrile- and ether-type solvents) to achieve a balance between solvation (i.e., sufficient solubility of precursors) and desolvation (i.e., rapid crystallization of films) processes during perovskite synthesis. The polarity and hydrogen-bonding property of these cosolvents synergistically enhance their solvation capacity, facilitating perovskite precursor dissolution. Moreover, the low-solvation cosolvents accelerate the crystallization of well-defined intermediate films, yielding higher-quality perovskites than those synthesized with DMF. The optimized modules achieved an active-area efficiency of 22.27%, with a certified aperture-area efficiency of 16.10% and corresponding active-area efficiency of 20.75%. This research on solvation regulation provides universal guidelines for innovatively preparing high-quality halide perovskites. The solvation capacity of dispersion solvents plays a crucial role in the solution processing of metal halide perovskites. For instance, N,N-dimethylformamide (DMF), a widely used dispersion solvent, possesses high solvation capacity but often generates suboptimal film quality due to slow crystallization kinetics. We propose using low-solvation binary cosolvents (nitrile- and ether-type solvents) to achieve a balance between solvation (i.e., sufficient solubility of precursors) and desolvation (i.e., rapid crystallization of films) processes during perovskite synthesis. The polarity and hydrogen-bonding property of these cosolvents synergistically enhance their solvation capacity, facilitating perovskite precursor dissolution. Moreover, the low-solvation cosolvents accelerate the crystallization of well-defined intermediate films, yielding higher-quality perovskites than those synthesized with DMF. The optimized modules achieved an active-area efficiency of 22.27%, with a certified aperture-area efficiency of 16.10% and corresponding active-area efficiency of 20.75%. This research on solvation regulation provides universal guidelines for innovatively preparing high-quality halide perovskites.

Solvothermal synthesis of KNbO<sub>3</sub> nanocubes using various organic solvents

Potassium niobate (KNbO3) nanocubes were synthesized via a solvothermal method using various organic solvents as the reaction medium. The solvothermal synthesis was conducted in different alcohols and ether-type solvents, and in mixtures of alcohol and ether-type solvents. The starting materials for the solvothermal synthesis were niobium oxide and potassium hydroxide. X-ray diffraction confirmed the presence of perovskite-structured KNbO3. The morphology of KNbO3 was investigated using scanning electron microscopy, transmission electron microscopy, and scanning transmission electron microscopy (STEM). Energy-dispersive X-ray (EDX) spectrometry was used to determine the elements present in the KNbO3. The KNbO3 nanocubes were the same length as the alkyl chain in the solvent that was used. The STEM and EDX analyses indicated that three elements, potassium, niobium, and oxygen, were present in the KNbO3 nanocubes, and that these elements were distributed homogeneously throughout the nanocubes.

Highly soluble and colorless fluorinated poly(ether imide)s based on 4,4’-(2,5-tolylenedioxy)diphthalic anhydride and trifluoro methyl-substituted aromatic bis(ether amine)s

AbstractA series of novel fluorinated poly(ether imide)s (PEIs) IVa-h were synthesized from 4,4’-(2,5-tolylenedioxy)diphthalic anhydride (I) and various trifluoromethyl-substituted aromatic bis(ether amine)s (IIa-h) via a conventional two-step method with thermal or chemical imidization of the precursor poly(amic acid)s. These PEIs were readily soluble in a variety of organic solvents; they were soluble with a concentration higher than 10% in amide-type polar solvents, ether type solvents, and chlorinated hydrocarbons. The solution-cast films showed a high optical transparency and low color intensity, with an ultraviolet-visible absorption edge of 371- 377 nm and low b* values (a yellowness index) of 4.9-7.5. These films were strong and tough with tensile strength of 90-103 MPa. They exhibited glass-transition temperatures (Tg) in the range of 207-293oC, with 10% weight loss temperature in excess of 500oC in air or nitrogen atmosphere. They also showed low-dielectric constants (2.95-3.37 at 1 MHz) and low moisture absorption (0.20- 0.67 wt %).

Frothability characterization of residual organic solvents

Organic solvents were evaluated through the determination of froth volume and bubble collapse rate in a froth column meter under various solvent dosages and aeration rate levels. There is a non-linear relationship between the froth volume and the gas flow rate for polyglycol ether type solvents. It is inappropriate to apply the concept of linearity retention time to describe the frothing characteristics of polyglycol ethers. Two new parameters are derived to characterize the foam stability and non-persistency of the frothers. The new parameters are initial dynamic froth index (IDFI) and initial dynamic froth collapse rate (IDCR). IDFI represents the froth volume formation properties, and can be used to relate to the ultimate recovery, Rm, and the flotation rate constant, K. IDCR describes the non-persistency of the froth, and can be used to relate to the quality of flotation concentrates. IDFI value depends on chemical structure and molecular weight of a solvent. Increasing solvent molecular weight and number of hydrophobic groups increases the IDFI value. Both ultimate recovery and flotation rate constant can be maintained at a desirable level, if the solvent dosage is applied in the amount to give the same product value of IDFI and solvent dosage. The selection of potential frothers from solvents tested is made by using IDFI and IDCR and comparing with laboratory fine coal flotation performance.

Studies on the structure behavior of triphenyldichlorophosphorane in different solvents

Triphenyldichlorophosporane, which was prepared according to Appel reaction, was an efficient reagent for alkyl halide synthesis by virtue of having two replaceable groups on “pentavalent” phosphorus. The reaction of triphenylphosphine with hexachloroethane was investigated in different solvents and 31P NMR traced the processes of these reactions. As results, it was found that there was similar high coordinated phosphorus species formed in aromatic solvents and in ring ether type solvents, which had large 1JP–C (about 140Hz) according to 13C NMR experiments. It is indicated that, for some solvent such as benzene or dioxane, solvent molecules might be locked in the high coordinated phosphorus compounds, which in turn would affect the triphenyl groups situated at the equatorial position.

Asymmetric reduction of acetophenone and propiophenone by NaAl(IPTOLate)H2 combined with enantiomeric enrichment of the reaction product as an inclusion complex with IPTOL

An improved procedure was developed for asymmetric reduction of acetophenone and propiophenone by the chiral reagent NaAl(IPTOLate)H2. This procedure is based on isolation of the chiral alcohol that formed as a crystalline host—guest complex with the IPTOL ligand. The enantiomeric enrichment of the product was as high as 97% ee. The ability of IPTOL and its analogs to form host—guest complexes with a number of ether-type solvents, 1-phenylethanol, and 1-phenylpropan-1-ol as well as thermal stabilities of IPTOL-containing complexes with these alcohols were studied.

Historical perspectives on living anionic polymerization*

A brief overview of the role that Dr. Michael Szwarc has played in unraveling the mechanism of living anionic polymerization is presented. Emphasis is placed on the different ionic species that control the propagation reaction in ether-type solvents.

Role of the solvent in optical resolution of trans-chrysanthemic acid via diastereomeric salt formation with (1R,2R)-1-(4-nitrophenyl)-2-dimethylaminopropane-1,3-diol

Optical resolution of trans-chrysanthemic acid via diastereomeric salt formation with (1R,2R)-1-(4-nitrophenyl)-2-dimethylaminopropane-1,3-diol (DMAD) has been studied in different solvents. Ether type solvents containing MeOH were found to be preferred. The role of MeOH was interpreted on the basis of powder and single crystal X-ray diffraction and DSC/TG measurements. We found that MeOH was incorporated into the crystals of the less soluble diastereomer salt of the 1R acid with DMAD in a non-stochiometric amount and postulated to promote nucleation and crystal growth.

Li-Graphite Intercalation Compounds Synthesized in Various Ether-Type Organic Solvents

Intercalation of Li into graphite was performed by a chemical method in various ether-type solvents oftetrahydrofuran (THF), 2-methyl tetrahydrofuran (2-MeTHF), 2, 5-dimethyl tetrahydrofuran (2, 5-diMeTHF), 1, 2-dimethoxyethane (DME), 1, 2-diethoxyethane (DEE), 1, 2-dibutoxyethane (DBE), 1, 2-dimethoxymethane (DMM), 1, 2-diethoxymethane (DEM), 1-methoxypropane (MP), 1-methoxy-butane (MB), diethyl ether (Et2O) and resultant products were studied by X-ray diffraction. For the solvents of THF, DME, DEE, DBE, DMM, DEM, ternary Li-solvent-graphite intercalation compounds (GIC) were obtained. On the contrary, for the other solvents, only Li intercalated into graphite to form binary Li-GIC. The criteria for the solvent co-intercalation were discussedin terms of the electron donicity of the solvents, the size of the solvents and also the size of Li-solvent complexes.

Effects of Solvent Molecular Size on Rates of Topomerization in Organolithium Compounds

Abstract Rates of topomerization of substituted 9-fluorenyllithiums and α-(benzylthio)benzyllithium were determined in various ether-type solvents by the dynamic NMR technique. The rates are small in solvents of bulky molecules in comparison with those of less-bulky molecules. UV-vis spectra of these compounds in the solvents indicate that the compounds tend to exist as solvent-separated ion pairs in solvents of small molecular size, whereas they exist as contact ion pairs in solvents of bulky molecules. 1H NMR spectra did not show signals attributable to two species at the lowest temperature of study. From these results, it is concluded that the observed process is the tumbling of the anion in solvent-separated ion pairs with a rapid pre-equilibrium between contact ion pairs and solvent-separated ion pairs, further intervention of solvent molecule(s) into the observed solvent-separated ion pairs being the rate-limiting step. A term, dimensiosolvatic effect, is proposed for the effects where the solvent molecular size plays important roles in determining rates of reaction or equilibria.

Intercalation of lithium into natural graphite flakes and heat-treated polyimide films in ether-type solvents by chemical method

X-ray diffraction and Raman spectroscopy have been used to study the intercalation of Li into natural graphite flakes and heat-treated polyimide films (HTT = 1800–3000 °C) by chemical method in various ether-type solvents. Here, naphthalene was used as a dissolving agent for Li, and the solvents were tetrahydrofuran (THF), 2-methyltetrahydrofuran (MeTHF), 2,5-dimethyltetrahydrofuran (diMeTHF), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1-methoxypropane (MP), 1-methoxybutane (MB) and diethyl ether (Et 2O). First, to elucidate the effects of the solvents, natural graphite flakes were used as a host material. By use of THF, DME and DEE, co-intercalation of Li and these solvents occurred to form ternary Li—solvent graphite intercalation compounds (GICs), but binary Li-GICs without solvents were obtained in MeTHF, diMeTHF, MP, MB and Et 2O solvents. These results were confirmed by (00 l) X-ray diffraction patterns. Second, co-intercalation of Li and THF into the heat-treated polyimide films was studied mainly by use of the Raman scattering results. As a result, co-intercalation of Li and THF occurred to form Li—THF—GIC for highly graphitized polyimide films heat-treated above 2400 °C, while only Li was found to be intercalated into the less graphitized films heat-treated below 2100 °C.

Preparation of alkali metal graphite intercalation compounds in organic solvents

Abstract Binary alkali metal graphite intercalation compounds (GICs) and ternary alkali metal organic solvent GICs have been prepared from natural graphite flakes in ether-type solvents containing alkali metals. Here, phenanthrene is used as a dissolving reagent for alkali metals. The stage structures of GICs prepared from five alkali metals; Li, Na, K, Rb and Cs, and four solvents; tetrahydrofuran (THF), 2-methyltetrahydrofuran (MeTHF), 2,5-dimethyltetrahydrofuran (diMeTHF), 1,2-dimethoxyethane (DME) and 1-methoxybutane (MB) are studied by X-ray diffraction. When the THF and DME solvents are used, ternary alkali metal organic solvent GICs are obtained, irrespective of the type of alkali metal. In contrast, binary alkali metal GICs are formed for some limited combinations of alkali metals and organic solvents such as MeTHF. diMeTHF and MB. In the case of MeTHF, the intercalation of Li, Na and K into graphite takes place without the solvent to form binary alkali metal GICs, but Rb intercalates into graphite both with and without the solvent to form ternary and binary GICs, and furthermore only ternary GIC is formed with Cs. In diMeTHF, binary GICs with Li and Cs and ternary GICs with K and Rb are formed. Binary GICs with Li and K are synthesized in MB.

Interactions between ions and free or immobilized ligands. Application of the competition method

Application of a competition method to determine affinities of ligands for ionic species in low polarity media is described. A soluble ligand, L, and a network-immobilized ligand, N, are allowed to interact with the counterion of an ionic chromophore A” according to the reaction NM+A− + L LM+A− + N (K). K values were determined in toluene and in ether-type solvents for linear and macrocyclic polyethers and polyamines, as well as for other cation-complexing agents, by varying either N or L. In solvents such as dioxane, binding constants of M+A− to N can be determined directly. Combined with K values they yield the complex formation constant, KL, of the reaction M+A− + L LM+A−.

An ESR study of ion pairing in solutions of the alkali metal salts of tetracyanoquinodimethan (TCNQ) and tetrafluorotetracyanoquinodimethan (TCNQF4)

ESR studies of the alkali metal salts of the anion radicals of tetracyanoquinodimethan (TCNQ) and tetrafluorotetracyanoquinodimethan (TCNQF4) in dilute solutions of ether type solvents reveal that solutions of salts of both anion radicals are ion paired. Quantitative measurements of the values of the hyperfine splittings (hfs) as a function of temperature for these salts in solution show that the isotropic hfs are temperature and solvent dependent. In contrast, the observed isotropic g-value for a given salt of either anion radical in solutions of the solvents studied is independent of temperature and solvent. However, there is a weak dependence of the isotropic g-value upon the alkali metal ion in the case of the heavier alkali metal ion salts, i.e., Cs/TCNQ, Rb/TCNQF4, and Cs/TCNQF4. The studies reported here (1) re-enforce an earlier report of ion pairing in solutions of the potassium salts of TCNQ and TCNQF4, (2) establish that ion pair formation occurs in the entire alkali metal TCNQ and TCNQF4 salt ...

Hydrolysis of p-nitrophenyl alkanoates in aqueous organic solvent mixtures. The dispersal of aggregates and the uncoiling of n-alkyl chains

Rate constants have been measured for the hydrolysis of six p-nitrophenyl alkanoates (C2, C4, C6, C8, C10, and C12) in basic aqueous media containing up to 80% (v/v) of the cosolvents: ethylene glycol (EG), 2-methoxyethanol (2ME), 1,2-dimethoxyethane (DME, glyme), bis(2-methoxyethyl) ether (diglyme), or DMSO. Addition of these cosolvents reduces and ultimately removes hydrophobic aggregation and coiling of the longer chain alkanoates, with the ether-type solvents (2ME, DME, and diglyme) being more efficient than EG or DMSO. Once the rate-lowering effects of aggregation and coiling have been removed by addition of a cosolvent, the rates of hydrolysis of the C4–C12 esters are all virtually the same, in a given medium. Thus, the apparent "steric size" of the C4–C12 (and even C16) acyl chains does not differ significantly in basic p-nitrophenyl ester hydrolysis. Addition of DMSO brings about rate increases that are greater in a carbonate buffer (pH 10.48) than those in 0.05 M NaOH solution, and these increases are larger than those observed for ethyl acetate in 0.05 M NaOH solution. None of the rate increases rise as quickly as the enhanced basicity of aqueous DMSO media.

An E.S.R. study of the ion pairs of the anion radicals of tetracyanoquinodimethan (TCNQ) and tetrafluorotetracyanoquinodimethan(TCNQF4) in solution

A comparative E.S.R. study of the potassium salts of the anion radicals of tetracyanoquinodimethan(TCNQ) and tetrafluorotetracyanoquinodimethan(TCNQF4) in dilute solutions of ether type solvents reveals that both anion radicals are ion paired. Careful measurements of the hyperfine splittings (hfs) as a function of temperature for both anions in solution show that the isotropic hfs are temperature and solvent dependent. Generally, at temperatures below room temperature, both anion radicals in solution display linewidth alternation phenomena which arise from modulation of the nitrogen and fluorine hfs in TCNQ and TCNQF4, respectively. In contrast, the isotropic g-values of both anion radicals in solution are independent of temperature and the solvents used in this study. The experimental evidence, molecular orbital calculations of the charge density distribution in the free anion radicals, calculations of the ion pair association energies for various K+/TCNQ- and K+/TCNQF4 structures and comparison of the c...

Complex formation of trinitromethane and 1,1-dinitroethane with etheetype solvents

1. C-H acids of a number of polynitroalkanes with ether-type solvents form intermolecular hydrogen bonds, forming stable complexes with a 1∶1 composition. 2. The replacement of the methyl group in the α-position of C-H acids by a nitro group increases their proton donor capacity and the energy of the hydrogen bond, 3. The change in the structure of the investigated ethers-hydrogen acceptors — leads to a change in the value of the dissociation constant of the complexes and does not affect the shift of the C-D band and, consequently, the energy of the hydrogen bond.

Polymerization of ethylene oxide in dimethyl sulphoxide (DMS)

Comparison of the reactivity of various types of centres, especially of ions and ionic pairs, can give very valuable information about the type of reactions with the monomer and the medium. The reactivity of free ions in the polymerization of styrene [1] or propylene sulphide [2], in tetrahydrofuran (THF) as solvent for example, is approximately 3 orders of magnitude greater than that of ionic pairs; this is due to steric hindrance of chain propagation by the strong solvation of the latter and also to the greater capacity of the anion to polarize the attack monomer. The reaction capacity of ions and ionic pairs in the polymerization of epoxides is basically still an open question. The reaction kinetics of the oxo anions was detected only in hexamethylphosphorus triamide [3]. The free ions do not play any outstanding part in the ethylene oxide (EO) polymerization in ether-type solvents (THF, dimethoxyethane, dimethylene glycol and in the bulk process) when alkali metal cations are present [4, 5]. The aim of this work was to study the polymerization of this monomer in a more polar medium to establish the part played by the oxo anions in chain propagation. The selected monomer was ethylene oxide (EO) in DMS, because it was the most suitable.

The kinetics and mechanism of anionic polymerization of ethylene oxide in ether solvents

Most attention in studies of the mechanism of anionic polymerization has been given to the type of reactive centre present. The existing literature on the process, using epoxides, states that ionic pairs of alcoholate type play the main role [1]. The same applies also to ethylene oxide (EO) in tetrahydrofuran (THF) when alkali metal cations are present, with the one difference that the reactive centres associate to trimers in the range of large concentrations [2]. As the solvation of the ionic pair by this solvent plays a decisive part in all the transformations of the reactive centre, we attempted to find out the effects in other ether-type solvents having a solvating capacity differing from that of THF. We used for this purpose the dimethoxy-ethane (DME) and the dimethyl ether of diethylene glycol (DG). We also studied the conductivity of the “live” poly-EO in THF.

ESR Studies of the Alkali Metal-Acenaphthene Ion Pairs

Abstract Ion pairs formed by alkali metals with acenaphthene in ether-type solvents have been investigated by means of electron spin resonance (ESR). The ESR spectra of the ion pairs were found to show phenomena quite analogous to those found by de Boer et al. in the pyracene-alkali ion system; similar two-line-width alternation effects were also observed in the present work. These observations were contrary to the expectations formed by a consideration of the pyracenealkali metal ion pair, where the phenomena have been explained on the basis of the assumption that a potential well exists near the two ethylene bridges. This paper shows that, in the acenaphthene-alkali metal ion pairs, the alkali ion may be situated above the naphthalene skeleton rather than near the ethylene bridge. One of the line-width alternation effects is explained in terms of the exchange reaction between two ion-pair conformations in which the alkali ion is situated above and under the molecular plane respectively, while the other is ascribed to the oscillation of the cation in the potential well above either side of the molecular plane.