Batches Of Crystals Research Articles

Morphology of Large ZSM-5 Crystals Unraveled by Fluorescence Microscopy

Understanding the internal structure of ZSM-5 crystallites is essential for improving catalyst performance. In this work, a combination of fluorescence microscopy, AFM, SEM, and optical observations is employed to study intergrowth phenomena and pore accessibility in a set of five ZSM-5 samples with different crystal morphologies. An amine-functionalized perylene dye is used to probe acid sites on the external crystal surface, while DAMPI (4-(4-diethylaminostyryl)- N-methylpyridinium iodide) is used to map access to the straight channels in MFI from the outer surface. The use of these dyes is validated by studying the well-understood rounded-boat type ZSM-5 crystals. Next coffin-shaped ZSM-5 crystals are considered; we critically evaluate the seemingly conflicting 2-component and 3-component models that have been proposed to account for the hourglass structure in these crystals. The data prove that observation of an hourglass structure is essentially unrelated to a 90 degree rotation of the pyramidal crystal components under the (010) face. Hence, in perfectly formed coffin-shaped crystals, the straight channels can be accessed from (010). However, in other crystal batches, sections with a 90 degrees rotation can be found; they are indeed located inside the crystal sections under (010) but often only partially occupy these pyramidal components. In such a case, both straight and sinusoidal pores surface at the hexagonal face. The results largely support the 3-component model, but with the added notion that 90 degree rotated sections (as proposed in the 2-component model) are most likely to be formed inside the defect-rich, pyramidal crystal sections under the (010) faces.

Evolution of the Fermi Surface and Quasiparticle Renormalization through a van Hove Singularity inSr2−yLayRuO4

We employ a combination of chemical substitution and angle resolved photoemission spectroscopy to prove that the Fermi level in the gamma band of Sr(2-y)La(y)RuO(4) can be made to traverse a van Hove singularity. Remarkably, the large mass renormalization has little dependence on either k or doping. By combining the results from photoemission with thermodynamic measurements on the same batches of crystals, we deduce a parametrization of the full many-body quasiparticle dispersion in Sr(2)RuO(4) which extends from the Fermi level to approximately 20 meV above it.

Investigation of the Double Superconducting Transition and Low-Temperature Specific Heat of Pr(Os1-xRux)4Sb12

The double superconducting transition in PrOs4Sb12, first observed in specific heat C(T) measurements on single crystal samples, was studied by means of specific heat measurements on PrOs4Sb12 crystals that had been subjected to applied magnetic fields, substitution of up to 4 Ru for Os, and annealing. The double superconducting transitions of a batch of single crystals were measured before and after annealing for 5 days at 500°C, to remove strains and promote homogeniety, with no observed change. Measurements of C(T) near Tc for PrOs4Sb12 in several magnetic fields are also presented, detailing the evolution of the double transition up to 1 T. Samples of Pr(Os1-x Rux)Sb12 with 0.01 ≤ x ≤ 0.04 also appear to display a double superconducting transition in specific heat. In addition, samples with the smallest Ru concentration measured (x = 0.01) may even display a more isotropic type of superconductivity than pure PrOs4Sb12 (x = 0).

Nested Fermi Surface and Electronic Instability inCa3Ru2O7

High-resolution angular resolved photoemission data reveal well-defined quasiparticle bands of unusually low weight, emerging in line with the metallic phase of Ca(3)Ru(2)O(7) below approximately 30 K . At the bulk structural phase transition temperature of 48 K, we find clear evidence for an electronic instability, gapping large parts of the underlying Fermi surface that appears to be nested. Metallic pockets are found to survive in the small, non-nested sections, constituting a low-temperature Fermi surface with 2 orders of magnitude smaller volume than in all other metallic ruthenates. The Fermi velocities and volumes of these pockets are in agreement with the results of complementary quantum oscillation measurements on the same crystal batches.

Perylene salts of unsymmetrical nickel and gold dithiolene complexes with 3 ? 2 stoichiometry: conformational polymorphism and strong antiferromagnetic interactions

The square-planar AuIII complex of the unsymmetrical tfadt dithiolate ligand (tfadt: 2-(trifluoromethyl)acrylonitrile-1,2-dithiolate) is found to exhibit conformational polymorphism in its n-Bu4N+ salt, as both cis and trans isomers were found to crystallize separately in the same crystallization batch. Electrocrystallization of perylene in the presence of the diamagnetic [n-Bu4N][Au(tfadt)2] or the paramagnetic (S = 1/2) [n-Bu4N][Ni(tfadt)2] nickel analog affords isostructural salts with an unusual 3 ∶ 2 stoichiometry, that is [Per]3[M(tfadt)2]2 (M = Au, Ni), with an alternation of dicationic [Per]32+ perylene triads and dianionic [M(tfadt)2]22− dithiolene complex dyads within one-dimensional chains. These salts are characterized by strong antiferromagnetic interactions within perylene triads and [Ni(tfadt)2]22− dyads and an essentially diamagnetic behaviour.

Non-proportionality and thermoluminescence of LSO:Ce

This work presents the results from experiments performed on Lu/sub 2/SiO/sub 5/:Ce (LSO:Ce). It looks for potential correlations of light yield nonproportionality and other scintillation properties such as intrinsic energy resolution with thermoluminescence properties. The analyzed samples were chosen from various crystal batches having significantly different properties. Single crystal LSO:Ce samples were coupled to an XP2020Q photomultiplier and to large area avalanche photodiodes and measured as a function of /spl gamma/-ray energy between 14.7 and 1770 keV at room temperature and also near liquid nitrogen temperature. To explain the experimental results obtained from spectrometric methods, the properties of the samples were further studied using thermoluminescence techniques within the temperature range from 250K to 600K. The relationships between data obtained from these two types of experiments are reported.

The temperature of flash-cooling has dramatic effects on the diffraction quality of nucleosome crystals

Nucleosome core-particle crystals are routinely flash-cooled in liquid propane at temperatures of approximately 153 K, followed by transfer into a cold nitrogen-gas stream (approximately 93 K). Analysis of diffraction data from crystals flash-cooled at different temperatures shows that the optimal temperature is approximately 153 K. The data quality worsens, with a concomitant reduction in the diffraction limit, at temperatures both higher and lower than 153 K. With some batches of crystals, significant shrinkage of the unit-cell volume is also observed at temperatures of 138 K and lower. The lattice shrinkage is always restricted to the c axis, concurrent with closer packing of two nucleosomes. Direct plunge-cooling of crystals in liquid nitrogen leads to loss of diffraction quality and resolution limit. Thus, in cases where flash-cooling into liquid nitrogen is detrimental to diffraction, optimizing cooling protocols at higher temperatures using liquid propane or other cryogens with similar properties may lead to dramatically improved results. In a related study, it is shown that a nucleosome crystal transported under 'cryocooled' conditions has higher mosaicity and yields inferior data quality in comparison to a crystal cryocooled at the synchrotron. For fragile crystals, transport in mother liquor and/or cryoprotectant followed by subsequent flash-cooling at the synchrotron may be the best procedure.

K3Sn5Cl3F10with a corrugated layered structure

Single crystals of K3Sn5Cl3F10, tri­potassium trichloro­deca­fluoro­penta­stannate(II), were isolated from a batch of needle-shaped crystals containing several potassium tin(II) fluorides, chlorides and chloride fluorides. The title compound crystallizes in the centrosymmetric space group Cmcm and the unit cell contains three crystallographically distinct tin units, with one SnF3Cl2E, in the unusual SnX5E pseudo-octa­hedral coordination, while the other two are in an SnX4E pseudo-trigonal bipyramid (E is a stereoactive lone pair). The SnF3Cl2 units form [SnF2Cl2]n2n− rows parallel to the a axis of the unit cell, sandwiched between rows of [Sn2F4]n units also parallel to the a axis, with adjacent [Sn2F4]n rows being held together by rows of Cl− ions, also parallel to a. This ensemble forms [(Sn2F4)(SnF2Cl2)(Sn2F4)Cl]n3n− anionic planes parallel to ac. Two adjacent anionic planes, their terminal F atoms pointing towards each other, are held together by K+ ions and form bilayers. Each pair of adjacent bilayers is separated by a sheet of Sn lone pairs, making the structure highly layered.

Characterization of pilot batch of LuYAP crystals to be used in prototypes of small animal positron emission tomograph ClearPET

Small animal positron emission tomograph ClearPET® is under development by Crystal Clear Collaboration, CERN. ClearPET® detector with Depth Of Interaction (DOI) determination capability is based on LSO and (Lu-Y)AlO3:Ce (LuYAP) scintillation crystals. Pilot batch of LuYAP crystals was grown at Bogoroditsk Techno Chemical Plant, and more than 9000 scintillation elements (pixels) with dimensions 2×2×8mm3 and 2×2×10mm3 were manufactured for small animal PET prototyping. During this effort, complete characterization of scintillation properties of grown crystal and selective control of scintillation pixels was performed. The aim of this work is to evaluate repeatability of LuYAP production technology and uniformity of scintillation pixel parameters. Methods and main results of characterization are presented.

μSR study of [Mn 12O 12(O 2CC 6H 5) 16(H 2O) 4]·2C 6H 5CO 2H

The crystals of a Mn 12 cluster, [Mn 12O 12(O 2CC 6H 5) 16(H 2O) 4]·2C 6H 5CO 2H, are mosaic involving two kinds of molecules with different relaxation rates. The ratios of the two components in the crystals are strongly batch-dependent. We prepared a batch of crystals in which mainly contained the fast relaxation (FR) species and studied the muon spin relaxation (μSR) measurements in the range 0.3–80 K at zero-field (ZF). As the temperature was lowered, the decay of the muon asymmetry showed systematic temperature dependence: the dynamic and the static behavior of the internal-field appear alternately. This is probably due to the magnetization blocking of the FR molecule.

Crystal modification of phenytoin using different solvents and crystallization conditions

Phenytoin crystals having different types of habits, were prepared by recrystallization from ethanol and acetone solutions under different conditions (cooling rate or crystallization temperature, solvent evaporation and watering-out techniques). Scanning electron microscopy, X-ray powder diffractometry, FT-IR spectrometry and differential scanning calorimetry were used to investigate the physical characteristics of the crystals. The dissolution behavior and compaction properties of various batches of crystals were also studied. It was found that using watering-out technique as a crystallization method, produced thin plate crystals, while the crystals obtained by other methods were needle shape for alcoholic solutions and rhombic for acetone solutions. X-ray diffraction spectra and differential scanning calorimetry studies, did not show any polymorphic change. The dissolution rate of different crystals was lower than that of untreated samples. The compacts of phenytoin crystals produced from alcohol or acetone (especially those made by watering-out method) had higher crushing strengths than untreated phenytoin compacts due to the lower porosity and the lower elastic recovery.

Effects of initial particle size on the tableting properties of l-lysine monohydrochloride dihydrate powder

l-lysine monohydrochloride (LMH) dihydrate was crystallized and the resulting powder was sieved to obtain various size fractions. The influence of other factors, such as crystallinity and crystal shape, was minimized by using the same batch of crystals. Compression of smaller particles at low compaction pressures resulted in tablets of greater porosity. The differences in porosity decreased with increasing compaction pressure. At the same compaction pressure, smaller particles formed tablets of greater tensile strength. However, fragmentation of the larger particles tended to equalize the particle size and reduce its influence. The differences were reduced for particles larger than 710 μm. For crystals of all size fractions, tensile strength increased with increasing compaction pressure. The tensile strength increased more rapidly for smaller crystals. Tensile strength decreased exponentially with increasing porosity for all fractions. The dependence of tensile strength on porosity is explained in term of tablet structure. Yield strength, calculated from ‘out-of-die’ Heckel analysis, increased with increasing particle size.

Racemic Compound FormationversusConglomerate Formation with [M(bpy)3](PF6)2 (M = Ni, Zn, Ru); Molecular and Crystal Structures

Minor modifications in molecular size and shape induced by variation of the central atom drastically alter the crystallization behaviour of the hexafluorophosphate salts of [M(bpy)3]2+. With M = Ru, racemic solutions crystallize as true racemates in the β-type [P3¯c1, a = 10.6453(5), c = 16.2987(9) A, Z = 2], while for M = Zn the racemic structure cannot be obtained, as spontaneous resolution {γ-type [P31, a = 10.3873(5), c = 26.1309(16) A, Z = 3]} is the only crystallization path observed. For [Ni(bpy)3](PF6)2, crystals of both structural types can be obtained concomitantly from the same crystallization batch. The γ-phase is systematically twinned by merohedry. The dramatic and unpredictable change in the packing pattern of the very similar building blocks within this series arises from a delicate balance between the intermolecular forces. Distinct intermolecular interactions with different directionalities can be identified in the two structure types. Through careful analysis of the crystal and molecular structures, a trend with respect to molecular size and shape on going from [Ru(bpy)3](PF6)2 to [Zn(bpy)3](PF6)2 can be established. Even though one might speculate that increasing the size of the molecular cation should destabilize the β-type structure relative to the γ-type, no conclusive rationalization based solely on structural parameters can be given as regards why the relative order of the two local minima on the energy hypersurface should become inverted.

Relations between crystallisation conditions and micromeritic properties of ibuprofen

The effects of solvent, cooling rate and type of methacrylic polymer (Eudragit®) on the micromeritic properties (size, elongation ratio, roundness and fullness ratio), the temperature change in the crystallisation liquid, the crystal yield and the extent of agglomeration of ibuprofen crystals have been compared. Twenty batches of crystals were prepared and Latin square experimental design was applied with four levels for each factor. It was found that crystal yield ( Y) is related to the extrapolated point of maximum rate of temperature-deviation ( T d) with a logarithmic-type equation [ Y=34.45 ln T d−28.00] and to the area under the curve of temperature-deviation versus time (AUC) with a polynomial equation including cooling rate [ Y=19.95AUC−1.57AUC/CR+63.00]. Crystal size is affected by the cooling rate and analysis of variance (ANOVA) showed that elongation ratio and fullness ratio of single crystals ( P=0.05 and 0.05), as well as roundness and fullness ratio of agglomerates ( P=0.05 and 0.1), are affected by the solvent. Post hoc statistical analysis of the solvent effects on the shape of crystals and agglomerates (Tukey’s HSD multiple pairwise comparison test of means) indicated that their significance lies in the different polarity and may be attributed to interactions of solvent (acetone) with the growing crystal faces. Extent of crystal agglomeration was found to be inversely proportional to the ratio of elongation ratio/circle equivalent diameter of the single crystals.

Crystallization of lactose from carbopol gels.

To crystallize lactose under static conditions with a view to preparing crystals of well-defined morphology. et-Lactose monohydrate was crystallized from neutralized Carbopol 934 gels. When the majority of crystals had grown to maturity, the gels were acidified using diluted hydrochloric acid and the crystals were harvested by filtration or centrifugation and washed with ethanol-water mixtures. Crystals prepared from the gel had a consistently narrower size distribution than control crystals, prepared from solution under constant stirring. If crystallization was effected in the gel without sedimentation of the crystals, then the resultant crystals had smooth surfaces without visually detectable surface roughness or asperities viewed by optical microscopy. The crystals from Carbopol gels also exhibited the uniform shape of an elongated tomahawk regardless of the crystallization conditions, in contrast to crystallization under constant stirring, where the crystal shape of lactose changed with crystallization conditions especially as a function of the initial concentration of lactose. All batches of lactose crystals prepared from Carbopol gels existed as alpha-lactose monohydrate, which showed better flowability than the controls of a similar particle size. Crystallization from Carbopol gel produces lactose crystals of uniform size, regular shape, smooth surface, and improved flowability.

The Effect of Temperature and Solution pH on the Nucleation of Tetragonal Lysozyme Crystals

Part of the challenge of macromolecular crystal growth for structure determination is obtaining crystals with a volume suitable for x-ray analysis. In this respect an understanding of the effect of solution conditions on macromolecule nucleation rates is advantageous. This study investigated the effects of supersaturation, temperature, and pH on the nucleation rate of tetragonal lysozyme crystals. Batch crystallization plates were prepared at given solution concentrations and incubated at set temperatures over 1 week. The number of crystals per well with their size and axial ratios were recorded and correlated with solution conditions. Crystal numbers were found to increase with increasing supersaturation and temperature. The most significant variable, however, was pH; crystal numbers changed by two orders of magnitude over the pH range 4.0–5.2. Crystal size also varied with solution conditions, with the largest crystals obtained at pH 5.2. Having optimized the crystallization conditions, we prepared a batch of crystals under the same initial conditions, and 50 of these crystals were analyzed by x-ray diffraction techniques. The results indicate that even under the same crystallization conditions, a marked variation in crystal properties exists.

Quantitative Characterization of Internal Defects in RDX Crystals

Size, shape, internal defects are very important properties of explosives crystals. These parameters play a role on both the explosive formulation processing and the detonic behavior of the explosive formulations. The use of explosive crystals free of solvent inclusions leads to decrease the shock sensitivity of cast explosive formulations. Many efforts for processing such high quality explosive crystals have been done and are still in progress. Qualitative observations of internal crystal defects can be performed by optical microscopy with matching refractive index. The purpose of this paper is to provide two accurate quantitative tools for internal crystal defects measurements. The first method is based on accurate measurements of the crystal apparent density. The second method records the mass of the species entrapped in the crystal internal cavities. Experiments are performed on two RDX batches. The strong correlation recorded between the results of the two complementary methods validates the measurements. Apparent density measurements provide an accurate global characterization of the internal defects population of a crystal batch sorting the crystals in function of their apparent density. The second method is a tool to identify the species entrapped in the crystals.

THE PHENOMENON OF CONGLOMERATE CRYSTALLIZATION. PART 50. THE CRYSTALLIZATION BEHAVIOR OF [trans-Co(en)2(NO2)2]ClO4 (I), MESO-[Co-trans-Me-(N-Me-ETHYLENEDIAMINE)2-trans-(NO2)2]ClO4 (II), K[trans-Co(β-ALANINATO)2(NO2)2] (III) AND THE ISOLATION AND PARTIAL STRUCTURAL DESCRIPTION OF (H5O2)[trans-Co(β-ALANINATO)2(NO2)2] (IV)

[trans-Co(en)2(NO2)2]ClO4 (I) crystallizes, at 22°C, from a deionized water solution, as a racemate, in space group P$1 (No. 2), with lattice constants: a = 6.581(2)Å, b = 8.274(1) Å, c = 12.660(3)Å, α = 77.28(2)Å, β = 76.58(2)°, γ = 75.20(2)° V = 638.71;Å3 and d(calc; MW = 370.59,z = 2) = 1.927gcm−3. A total of 2233 data were collected over the range of 4° ≤ 2θ ≤ 50° of these, 1961 (independent and with I ≤ 3σ(I)) were used in the structural analysis. Data were corrected for absorption (μ = 15.989 cm−1) and the relative transmission coefficients ranged from 0.6792 to 0.9874. The final R(F) and R≤(F) residuals were, respectively, 0.0738 and 0.0763. Two half cations are located at inversion centers; the anions are in general positions. meso-[Co-trans-Me-(N-Me-ethylenediamine)2-trans(NO2)2]ClO4 (II) [(N-Meen) = N-methyl-ethylenediamine] crystallizes at 22°C, from a deionized water solution in space group Pbca (No. 61) with lattice constants: a = 16.882(5) Å, b = 11.990(3) Å, c = 15.017(5) Å; V = 3039.72 Å3 and d (calc;MW = 398.64, z = 8) = 1.742g cm−3. A total of 5281 data were collected over the range of 4° ≤ 2θ ≤ 50° of these, 1779 (independent and with I ≤ 2.5σ(I) were used in the structural analysis. Data were corrected for absorption (μ = 13.501 cm−1 and the transmission coefficients ranged from 0.7956 to 0.9947. The final refinement of the structure (anisotropic thermal parameters for the heavy atoms; idealized hydrogens for the cation) are R(F) = 0.045 and Rw (F) = 0.052). The -NO2 ligands are trans to one another in the axial direction while the N-methyl groups are trans to one another across the basal plane. The cations are located in general positions and the torsional angles of the en rings are δ(N1-C1-C2-N2 = 52.0°) and δ(N3-C3-C4-C4 = 51.0°), in contrast with those of (I) which are of opposite helical chirality. This compound is one of two trans-Co(III)X2 cations of which we are aware that, while sitting at a general position of the space group, has two ethytenediamine rings of the same helical chirality. K[trans-Co(β-alaninato)2(NO2)2] (III) obtained after several batches of crystals of (TV) had separated from the mother liquor (see Syntheses). (III) crystallizes at 22°C, in space group Cc (No. 9) with lattice constants: a = 12.385(6)Å, b=13.109(5)Å, c = 8.290(5)Å, β=115.19° V = 1217.97 Å3 and d(calc; MW = 366.22, z = 4) = 1.997 g cm−3. A total of 1238 data were collected over the range of 4° ≤ 2θ 50° of these, 1016 (independent and with I ≤ 2.5σ(I) were used in the structural analysis. Data were corrected for absorption (μ 17.90cm−1) and the transmission coefficients ranged from 0.5322 to 0.6627. The final R(F) and Rw (F) residuals were, respectively 0.020 and 0.022. Solution of the structure, using the first batch of crystals, proved that the compound isolated was the (H5O2)+ derivative (see below and Discussion). A later batch of crystals contained (III). We have previously observed the precipitation of hydronium salts, trapped by amine carboxylato salts of cobalt (see Discussion). The anions consist of two six-membered rings formed by the metal and two (O,N)-bound β-alaninato ligands; and, both have chair conformations. (H5O2) [trans-Co(β-alaninato)2(NO2)2] (IV) is the substance that first crystalized from an aqueous solution of (III) (see Experimental). It crystallizes, at 22°C, in space group Cc (No. 9) or C2/c (No. 15) with lattice constants: a=12.389(39)Å, b=13.120(11)Å, c=8.299(9) Å, β=115.09(19)° V=1221.72 Å3 and d(calc; MW=364.15, z=4) = 1.980 g cm−3. An incomplete data set of 1592 reflections was collected over the range 4° ≤ 2θ ≤ 50° because the crystal decomposes in air due to rapid loss of water of crystallization, as shown by differential scanning calorimetry. 956 data were independent with I ≤ 2.5°(I) and were used in the structural analysis. Data were not corrected for absorption because of decomposition of the crystal. The final R(F) and Rw (F) residuals were, respectively, 0.14 and 0.16. To the precision of such a data set, the anions are identical with those found in (III); however the cation, which sits at an inversion center, consists of a proton sandwiched between the oxygens of two waters thus forming (H5O2)+ cations similar to those we have described in the past (see Refs. [15–18]).

Crystal Engineering: Some Further Strategies

Structural studies currently underway in our group are reported in this paper. Molecular symmetry is rarely carried over into the crystal, posing problems when high-symmetry networks are desired. This is illustrated by the low-symmetry structure of 2,4,6-trinitromesitylene. However, the involvement of the Cl 3 supramolecular synthon ensures a hexagonal network structure for 2,4,6- tris-(4-chlorophenoxy)-1,3,5-triazine. Arguments following from the equivalence between molecular and supramolecular synthons lead to the tetragonal network structure of the 1:1 complex of tetraphenylmethane and CCl 4. With a similar reasoning, 4-(triphenylmethyl)benzoic acid is identified as a precursor of a supramolecular wheel-and-axle host substance. The study of novel and weaker intermolecular interactions is often useful. In N,N′-dibenzyl-1,4-cubanedicarboxamide, the acidity of the cubyl C-H groups leads to the formation of C-H···O hydrogen bonds. Polymorphism is a difficult challenge for the crystal engineer and, in its most intriguing manifestation, two crystalline forms of a substance appear in the same crystallization batch. This is observed for 4,4-diphenyl cyclohexadienone. The ultimate frontier in the subject is an understanding of the phenomenon of crystallization, and the unexpected crystal structure of quinoxaline, with five symmetry-independent molecules, could possibly represent a case of arrested crystallization.

Carbazole deprotonation by sodium metal mirror in various ethers: Structures with Na +-coordination numbers 3 and 4 to 7

Solutions of carbazole anions and sodium cations in aprotic ethers such as tetrahydrofuran, dimethoxyethane, diglyme, triglyme, tetraglyme, 15-crown-5 or 2.2.1-cryptand form a cation solvation system with a shallow potential and numerous local minima. Its experimental exploration allows to crystallize and structurally characterize contact ion multiples of Na +-solvated carbazole anion M − salts comprising polyether-solvated monomers [M −Na solv +] 1, solvent-shared dimers [M −Na solv +] 2 and solvent-separated polyions [(M −) nNa solv +] ( n − 1) − [Na solv +] ( n − 1) . Their Na + coordination numbers stretch from 3 to 7. Series of compounds, shape-selected from the same crystallization batch such as 3- and 7-coordinate [(M −) 3Na +] 2−[Na +(2.2.1-cryptand)] 2, 4- and 7-coordinate [(M −) 2Na +(THF) 2] −[Na +(2.2.1-cryptand)] as well as solvent-separated [M −][Na +(2.2.1-cryptand)] suggest potential cation solvation equilibria in the reductive deprotonation mixtures. The seven different carbazolate sodium salts presented, therefore, demonstrate the delicate energy balance, by which cation solvation can influence the crystallization of individual molecular crystals.