Crystalline Solvents Research Articles

Crystal growth, structure and optical properties of solvated crystalline Tris(8-hydroxyquinoline)aluminum(III)(Alq3)

Tris(8-hydroxyquinoline)aluminum(III) (Alq3) is characterized by crystallization in polymorphism both under vapor deposition and solvent evaporation. In this article, crystal growth of Alq3 in several organic solvents is studied. High quality bulk single crystals or crystalline microstructures are obtained, which depends on the varied conditions of crystallization. Two new crystalline solvates of Alq3(HCON(CH3)2) and Alq3((CH2OH)2) growing in N,N-dimethylformamide (DMF) and ethylene glycol (EG) have been obtained. X-ray diffraction analysis shows that their structures belong to new polymorphism bearing identical crystal symmetry, which is different to any solvated crystal phases reported before. The photoluminescent (PL) properties of the crystalline Alq3(HCON(CH3)2) and Alq3((CH2OH)2) are measured. Both crystals exhibit high quantum yield and long PL lifetime. In addition, the optical waveguide properties of Alq3(HCON(CH3)2) microstructures are investigated. It shows that solvated single-crystals or microstructures can be used as excellent light-emitting and propagation materials in miniaturized optoelectronic devices.

Effects of Different Amount of Crystalline Solvate Molecules on Solid Structures and Photophysical Properties of a Platinum(II) Moiety with 4,4′‐Dibromo‐2,2′‐Bipyridine Ligand

AbstractA platinum(II) complex Pt(DiBrbpy)Cl2 (1) based on 4,4′‐dibromo‐2,2′‐bipyridine ligand was synthesized and characterized. Interestingly, two solvated phases of 1 with different amounts of crystalline CH2Cl2 molecules, 1·1/3(CH2Cl2) (yellow) and 1·3/2(CH2Cl2) (red), were obtained. In the solid state, 1·1/3(CH2Cl2) exhibits a 3D supramolecular structure based on Pt(DiBrbpy)Cl2 monomer and emits a weak yellow luminescence at 541 nm (579, sh). In contrast, 1·3/2(CH2Cl2) displays a 2D layer structure based on Pt(DiBrbpy)Cl2 dimeric units and has a strong red luminescence centered at 624 nm. The results show that crystalline solvate molecule amount can not only influence the packing structures but also photophysical properties of the platinum moiety in solid state. Furthermore, the absorption and luminescence spectra of both phases were studied by TD‐DFT calculations.

Effect of phase symmetry on the NMR spectrum of acetonitrile oriented in a uniaxial–biaxial–uniaxial phase

We report here the measurement of the CH and the HH dipolar couplings of the methyl group of acetonitrile oriented in the biaxial liquid crystal potassium laurate/1-decanol/water system. These parameters show large variations when measured as a function of temperature. The variations follow the symmetry of the phase as the liquid crystal goes through the sequence of uniaxial – biaxial – uniaxial phases and show a close correspondence to the phase changes that occur in the liquid crystalline solvent coinciding with the onset of biaxiality. The HCH bond angle calculated after incorporating vibrational corrections to the dipolar couplings is discussed in terms of contributions in the case of the biaxial liquid crystal arising from vibration–rotation interaction effects.

Electron Transfer Pathways in a Tetrathiafulvalene-Aluminum(III) Porphyrin-Free-Base Porphyrin Triad Studied Using Electron Spin Polarization

The electron transfer pathways in two axially bound triads based on aluminum(III) porphyrin (AlPor) are investigated using the electron spin polarization patterns of the final radical pair state. In the triads, TTF-(Ph)n-py-AlPor-Ph-H2Por (n = 0, 1), free-base porphyrin (H2Por) is attached covalently to the Al(III) center, while the donor tetrathiafulvalene (TTF) coordinates to Al(III) via an appended pyridine on the opposite face of the porphyrin ring. Excitation of the triad at 532 nm leads to absorption by both AlPor and H2Por and to two possible charge separation pathways. In the liquid crystalline solvent 5CB, spin polarized transient electron paramagnetic resonance spectra of a weakly coupled radical pair are observed and assigned to the state \({\text{TTF}}^{ \cdot+ } {\text{H}}_{2} {\text{Por}}^{ \cdot- }\). The radical pair spectra are analyzed using a structural model of the complex to determine the dipolar coupling and relative orientation of the radicals. The inertia tensor calculated from the structural model is used to derive the principal values and axes of the order matrix. It is shown that the observed polarization pattern is only consistent with ferromagnetic exchange coupling in the radical pair. The spectra can be reproduced as the sum of two contributions originating in electron transfer from the excited singlet state of AlPor and from the excited the triplet state of H2Por. The latter is shown to account for the integral emissive net polarization observed in the spectra.

The effects of a solvent and a ligand shell on interaction of CdSe quantum dots: Molecular dynamics simulation

Molecular dynamics simulation has been performed for the interaction of CdSe quantum dots both uncovered and covered with shells composed of trioctylphosphine oxide molecules in solvents of different polarities (chloroform and methanol). A detailed model that takes into account the real structure of the crystalline core, ligands, and solvent molecules has been used. It has been found that an increase in the lyophobicity of the particles with respect to a solvent promotes aggregation thereof, while an increase in the lyophilicity leads, on the contrary, to dispersion of the particles in a colloidal solution. It has been shown that the influence of the ligand shell is not reduced to a change in the interaction of the quantum dot surface with a solvent. The transition from a soft organic shell to a rigid crystalline surface enables one to observe oscillating potential of mean force in a highly solvating environment due to the formation of a layered structure of a solvent in the gap between the facets of nanocrystals being approached.

Effect of Alkyl Tail on the Visible Spectra and Order Parameters S of some Azo N- Ester-1,8-naphthalimide(ANEN) Disperse Dyestuff

This research is an attempt to measure the effect of alkyl tail on the visible spectra and order parameters S of some azo N-ester-1,8-naphthalimide(ANEN) disperse dyestuff. For the first time, the visible absorption spectra of two azo N-ester-1,8-naphthalimide(ANEN) dyes with identical molecular size and diverse alkyl tails were obtained in liquids and liquid crystalline solvent. Ordinary organic solvents with different polarity and chemical nature (i.e. cyclohexane, 1,4-dioxane, tetrachloromethane, benzene, diethyl ether, chloroform, dichloromethane, 1-butanol, acetone, ethanol and methanol) accompanied by nematic liquid crystal matrix (5CB) were used. In the visible region of parallel aligned samples the intensity of the absorption bands was measured, thereby the dichroic ratios R and order parameters S of the dyes were determined. Then, the interaction of these dyes was investigated and compared with the anisotropic surroundings and those of the isotropic organic solvents. It was found that the electronic absorption spectra of the dyes in the alcoholic (methanol and/or ethanol) surroundings are shifted to red compared to that of the isotropic organic solutions. Thus, there are strong molecular interactions between the dye molecules and methanol molecules. Also, the electro-optical effects of the guest-host systems were investigated through polarized spectroscopic method.

Solid-State Characterization of Novel Propylene Glycol Ester Solvates Isolated from Lipid Formulations.

The purpose of this study was to identify and characterize precipitates obtained from a liquid formulation of GNE068.HCl, a Genentech developmental compound, and lipophilic excipients, such as propylene glycol monocaprylate, and monolaurate. Precipitates were characterized using powder X-ray diffractometry (PXRD), differential scanning calorimetry, thermogravimetry, microscopy, nuclear magnetic resonance spectroscopy (NMR; solution and solid-state) and water sorption analysis. PXRD and NMR revealed the precipitates to be crystalline solvates of propylene glycol esters. The solvates (capryolate and lauroglycolate) were isomorphic and stable up to 70 °C, beyond which melting of the lattice occurred with subsequent dissolution of the active ingredient in the melt (microscopy and variable temperature PXRD). They were found to be mechanically stable (no change in PXRD pattern upon compression) and were nonhygroscopic up to ∼70% RH (25 °C). Our results highlight the outcome of inadvertent drug-excipient interactions in two separate lipid solution formulations with good solid-state properties and, thus, potential for further development.

Synthesis, structures, luminescence and terahertz time-domain spectroscopy of seven lanthanide complexes with tetrakis(O-isopropyl)methylenediphosphonate and 1,10-phenanthroline

Seven lanthanide–organic frameworks [(CeCl2L(phen))2(μ-Cl)2]·CH3CN (1) (L=tetrakis(O-isopropyl)methylenediphosphonate, phen=1,10-phenanthroline) and [LnCl(H2O)3L(phen)]·nCH3CN (n=0 for 2, n=2 for 3, n=1.5 for 4, n=0 for 5, n=1.5 for 6, n=1.5 for 7) (Ln=Dy, Ho, Er, Tm, Yb, Lu for 2–7, respectively) have been synthesized by the reaction of lanthanide chlorides, the ligand L and phen in acetonitrile at room temperature. These title complexes were characterized by IR, elemental analyses, single-crystal X-ray diffraction analysis, luminescence, thermal analysis, 1H NMR and 31P NMR spectroscopy. The complex [(CeCl2Lphen)2(μ-Cl)2]·CH3CN (1) is a dinuclear compound and displays a two-dimensional mesh 63 topology formed by π–π interactions. Complexes 2–7 can be simplified as having a two-dimensional mesh 4.82 topology formed by hydrogen bonds (C–H⋯Cl and O–H⋯Cl). These interesting structures are rarely found. We found a fluorescence quenching phenomenon which may be due to the presence of crystalline water molecules and solvent. Their terahertz (THz) time-domain spectroscopy was also studied.

Development of a Manufacturing Process for an HCV Protease Inhibitor Candidate Molecule

The scale-up of a prototype HCV protease inhibitor (1) from gram scale in the laboratory to kilogram scale in the pilot plant is described. Key features of the optimization included the synthesis of bulk quantities of exomethylene proline intermediate 6, separation of the diastereomers of spirocycle 2 without chromatography, isolation of the precursor to 1 to purge byproducts that might raise genotoxic structural alerts, and purification of an amorphous drug substance via a crystalline acetic acid solvate.

Solvate structures and spectroscopic characterization of LiTFSI electrolytes.

A Raman spectroscopic evaluation of numerous crystalline solvates with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI or LiN(SO2CF3)2) has been conducted over a wide temperature range. Four new crystalline solvate structures-(PHEN)3:LiTFSI, (2,9-DMPHEN)2:LiTFSI, (G3)1:LiTFSI and (2,6-DMPy)1/2:LiTFSI with phenanthroline, 2,9-dimethyl[1,10]phenanthroline, triglyme, and 2,6-dimethylpyridine, respectively-have been determined to aid in this study. The spectroscopic data have been correlated with varying modes of TFSI(-)···Li(+) cation coordination within the solvate structures to create an electrolyte characterization tool to facilitate the Raman band deconvolution assignments for the determination of ionic association interactions within electrolytes containing LiTFSI. It is found, however, that significant difficulties may be encountered when identifying the distributions of specific forms of TFSI(-) anion coordination present in liquid electrolyte mixtures due to the wide range of TFSI(-)···Li(+) cation interactions possible and the overlap of the corresponding spectroscopic data signatures.

Structural Interactions within Lithium Salt Solvates: Cyclic Carbonates and Esters

Only limited information is available regarding the manner in which cyclic carbonate and ester solvents coordinate Li+ cations in electrolyte solutions for lithium batteries. One approach to gleaning significant insight into these interactions is to examine crystalline solvate structures. To this end, eight new solvate structures are reported with ethylene carbonate, γ-butyrolactone, and γ-valerolactone: (EC)3:LiClO4, (EC)2:LiClO4, (EC)2:LiBF4, (GBL)4:LiPF6, (GBL)1:LiClO4, (GVL)1:LiClO4, (GBL)1:LiBF4, and (GBL)1:LiCF3SO3. The crystal structure of (EC)1:LiCF3SO3 is also re-reported for comparison. These structures enable the factors that govern the manner in which the ions are coordinated and the ion/solvent packing—in the solid-state—to be scrutinized in detail.

Variety of Crystal Structures of Chiral Schiff Base Lu(III)-Ni(II)/ Cu(II)/Zn(II) and the Related Complexes

New mononuclear [Cu2(L1)2(H2O)]2H2O・CH3OH] (cyCu)2, multinuclear [Cu2(L1)2K2][Ni(CN)4] (cyCuKNi), and dinuclear Ni(L1)Lu(NO3)3 (cyLuNi), Cu(L1)Lu(NO3)3 (cyLuCu) and Zn(L1)Lu[(NO3)2CH3COO]CH3OH (cyLuZn) complexes incorporating chiral Schiff base ligands were prepared and characterized by various techniques such as solid-state CD spectra, diffuse reflectance electronic spectra, IR spectra, and single crystal X-ray diffraction analysis. Crystal structures were also compared with previous ones, namely [Cu(L2)](H2O) (diCu), Cu(L1)Gd(NO3)3 (cyGdCu). Interestingly, determined crystal structures exhibited drastically different structural characteristics as regards coordination numbers, crystalline solvents, features and strain condition, nevertheless with little modification in 3d metal substitution and/or modified organic ligands. In this paper, comparison of common components of structures will be discussed systematically.

Vapochromism of Organic Cocrystal Induced by Crystalline Solvent Exchange

Vapochromic materials, which show color change induced by vapors, are expected to be applied to the sensing of volatile organic compounds or humidity. As for the metal complex crystals, many vapochromic crystals are reported, however, vapochromic organic crystals are not common. Therefore, it is important to find vapochromic organic crystals and to reveal the mechanistic aspects of structure transformations and color change based on the crystal structures. Pale brown Enoxacin-3,5-Diaminobenzoic Acid (ENO-3,5DABA) dihydrate cocrystal changed to yellow on exposure to four kinds of alcohol solvent vapors (methanol, ethanol, 1-propanol, 2-propanol), and these yellow crystals returned to pale brown dihydrate crystal by humidity, which is called vapochromism. The single crystals recrystallized from water (pale brown) and methanol (yellow) are equal to the dihydrate and the methanol vapor applied forms, respectively, and their crystal structure determination revealed that the cocrystals are 1:1 salt of ENO and 3,5DABA. Surprisingly, in the methanol vapor applied from, the crystalline solvent was changed to 0.5-methanol-0.5-water solvate (composition is ENO:3,5DABA:MeOH:H2O=2:2:1:1). Thus the dihydrate cocrystal undergoes solvent exchange transformation on exposure to methanol vapor and the color changes from pale brown to yellow. Because the XRD patterns of the yellow 0.5-methanol-0.5-water solvate cocrystal and the forms exposed to other alcohol solvent vapors shows high similarity, they are isostructure crystals. The color change is caused by the π...π interaction formation between the ENO molecule and 3,5DABA molecule in alcohol solvate form via solvent exchange transformations.

Convenient Synthesis and Purification of N-Trifluoroacetylated Neuraminic Acid Tetraol: A Key Precursor for the Synthesis of New Sialyl Donors Containing Labile O-Acyl Protecting Groups

A convenient synthesis and separation of α- and β-anomers of methyl (phenyl 3,5-dideoxy-2-thio-5-trifluoroacetamido-D-glycero-D-galacto-nonulopyranosid)onate (6a and 6b) on a multigram scale was developed. Both α- and β-isomers of 6 were obtained as crystals suitable for safe storage. The β-isomer forms a crystalline solvate with methanol. Fully O-trichloroacetylated and O-trifluoroacetylated N-trifluoroacetyl thiosialosides were synthesized in an efficient manner from the β-tetraol 6b.

The Effect of the Enantiomeric Organization of the Solid Polymeric Electrolyte on the Ion Transport Properties Thereof

Solid Polymeric Electrolytes (SPEs) are systems which exhibit relatively high (in comparison to other solid-state systems) ionic conductivity at temperatures below 100ºC. The typical applications in which such systems can be used are electrochromic devices, fuel cells and lithium batteries. Usually, the SPE for the last above-mentioned applications consists of lithium salt dissolved in poly(ethylene oxide)- PEO. Optionally, various compounds, like ceramic powders, plasticizers or anion receptors are added to the electrolyte in order to enhance its ion transport properties. As the lithium cation conductivity of the solid-state electrolyte is several orders of magnitude lower in comparison to liquid systems (in which conductivity is at the level of about 10-2-10-3 S/cm), SPE-containing batteries can be used only in applications in which high energy density, low power density as well as low self-discharge of the battery is needed. To make the range of the possible applications for SPE-containing batteries, the lithium cation conductivity of such systems should be enhanced. One of the approaches to this problem is orientation of the electrolyte. It was proved that mechano-, electro-, or magnetoorientation of the electrolyte results in improvement of the transport properties thereof. Similar observations was made when orientation of the polyoxythylene chains by synthesis of liquid crystals and synthesis of crystalline solvates of the salts was tested. The enantioorientation of the electrolyte in the molecular level was proposed by Armand. This type of the organization of the membrane is realized by the use of the lithium salt bearing chiral anion, i.e. given enantiomer of the anion which has at least one asymmetric carbon Such application resulted in noticeable increase of the ionic conductivity, especially between 30 and 60°C. The studies conducted by Armand were, however, limited to PEO-potassium 10-camphorsulfonate system and the one in which asymmetric potassium salt of the assymeric imide of the triflic and 10-camphorsulfonic acid was used. It is worth to stress that the increase of the conductivity in the 30-60°C temperature range is very interesting when application of the SPE-containing battery as power source for peacemaker or (bio)sensor is taken into consideration. We decided to study systems containing amidates, being in which the amine part contain at least one assymeric atom of the carbon, and the acidic part comes from triflic (trifluoromethanesulfonic) acid. The tendency of such anion to ion pairing is similar to this of the triflate anion (CF3SO3 -). The important argument for this decision was that part of the amine can contain aromatic group. Paillard proved that the aromatic group can interact with the polymer matrix. Due to this, use of salt with anion containing phenyl ring in its structure should lead to the system of high lithium transference number. Therefore, it should be interesting to compare properties of the systems containing salts which anion contain (or do not contain) phenyl ring in its structure. In the presentation, the effect of chirality on the ion transport properties of the SPE will be presented. It will be shown that the organized systems (containing enantiomeric anion) exhibit better ion transport properties (lithium cation transference number and overall conductivity) in comparison to the ones which contain racemic mixtures of the enantiomers. Also the dependency between the chemical structure of the salt used and effect observed will be discussed.

Concentrated electrolytes: decrypting electrolyte properties and reassessing Al corrosion mechanisms

Highly concentrated electrolytes containing carbonate solvents with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) have been investigated to determine the influence of eliminating bulk solvent (i.e., uncoordinated to a Li+ cation) on electrolyte properties. The phase behavior of ethylene carbonate (EC)–LiTFSI mixtures indicates that two crystalline solvates form—(EC)3:LiTFSI and (EC)1:LiTFSI. Crystal structures for these were determined to obtain insight into the ion and solvent coordination. Between these compositions, however, a crystallinity gap exists. A Raman spectroscopic analysis of the EC solvent bands for the 3–1 and 2–1 EC–LiTFSI liquid electrolytes indicates that ∼86 and 95%, respectively, of the solvent is coordinated to the Li+ cations. This extensive coordination results in significantly improved anodic oxidation and thermal stabilities as compared with more dilute (i.e., 1 M) electrolytes. Further, while dilute EC–LiTFSI electrolytes extensively corrode the Al current collector at high potential, the concentrated electrolytes do not. A new mechanism for electrolyte corrosion of Al in Li-ion batteries is proposed to explain this. Although the ionic conductivity of concentrated EC–LiTFSI electrolytes is somewhat low relative to the current state-of-the-art electrolyte formulations used in commercial Li-ion batteries, using an EC–diethyl carbonate (DEC) mixed solvent instead of pure EC markedly improves the conductivity.

The First Aziridinylguanidinates: New Precursors for Potentially Volatile Metal Guanidinates

The first lithium-aziridinylamidinates, Li[(C2H4N)C(NR)2]·THF (R = iPr (3), Cy (4); iPr = isopropyl, Cy = cyclohexyl), have been prepared by addition of N-aziridinyllithium, C2H4NLi (2), to either N,N′-diisopropylcarbodiimide or N,N′-dicyclohexylcarbodiimide. The cyclohexyl derivative 4 was crystallised from both diethyl ether (Et2O) and THF to afford the crystalline solvent adducts {Li[(C2H4N)C(NR)2]·S}2 (4: S = THF; 4a: S = Et2O) which were structurally characterised by X-ray diffraction. In the solid state, these lithium-aziridinylamidinates comprise ladder-type dimeric molecular structures.

Colloid Science Collides with Liquid Crystals

Dynamic interactions of a colloidal particle with a liquid crystalline solvent can cause its diffusion to deviate from classical Brownian motion. [Also see Report by Turiv et al. ]

Ordered Structures from Crystalline Carbon Disulfide Solvates of the Nano-Tubular Fullerenes D5h(1)-C90 and D5h-C70

The structures of three crystalline solvates, D5h(1)-C90·CS2, D5h-C70·3CS2, and 2(D5h-C70)·3CS2, of nanotubular fullerenes have been determined by single crystal X-ray diffraction. Despite the marked tendency for fullerenes to disorder, the carbon cages in all three structures are fully ordered at 100(2) K for D5h(1)-C90·CS2 and 90 K for the other two crystals. Moreover, the carbon disulfide molecules are also ordered, except for the case of D5h(1)-C90·CS2, where there is a minor disorder in the solvate location. The molecular packing in D5h(1)-C90·CS2 reflects the nanotubular nature of the fullerene component with channels of alternating fullerenes and carbon disulfide molecules running along the crystallographic b axis. The molecular packing arrangements for D5h-C70·3CS2 and 2(D5h-C70)·3CS2 do not show such channels. In D5h-C70·3CS2, the carbon disulfide molecules form chains that snake between the fullerenes and along the crystallographic a axis. In 2(D5h-C70)·3CS2, there are two crystallographically distinct fullerene cages, which are segregated into individual layers. Within each layer, the fullerenes show hexagonal close packing and the carbon disulfide molecules form chains that snake between the fullerene layers in a zigzag fashion. The presence of diiodine in solution was essential for the formation of crystals of D5h-C70·3CS2 and 2(D5h-C70)·3CS2 that were suitable for structure determination, although no diiodine was incorporated in these crystals.

Ir spectroscopic and crystal morphology studies of the structure of alakli metal fluorophosphatozirconates (hafnates)

Potassium, rhubidium, and caesium fluorophosphatozirconates (hafnates) and oxo(hydroxo)fluorophosphatonitratometalates with PO 4 3− /Zr molar ratios of 2.0, 1.5, 1.0, 0.66, 0.5, and 0.33 are synthesized for the first time. Most of them form either fine crystalline or X-ray amorphous particles. In order to characterize them IR spectroscopy and SEM are used. For the crystalline compounds the types of PO4 groups and the character of bonds between fluorine and water are revealed. The occurrence of triple MeF4·Rb(PO4)0.33·RbNO3 (Me = Zr, Hf) salts and also M3Me3(PO4)5·3HF crystalline solvates is found. The layered habit of K3Hf3(PO4)5·3HF, RbHfF2PO4·0.5H2O, Rb3Hf3(PO4)5·3HF, CsHfF2PO4·0.5H2O, CsHf2F6PO4·4H2O, and CsH2Hf2F2(PO4)3·2H2O crystals gives grounds to suppose that the structure of these compounds is layered unlike the structure of triple MeF4·Rb(PO4)0.33·RbNO3 salts.