Crystal Polymorphism Research Articles

Whey as an Alternative Nutrient Medium for Growth of Sporosarcina pasteurii and Its Effect on CaCO3 Polymorphism and Fly Ash Bioconsolidation.

Whey in large quantities can cause environmental problems when discarded, because it reduces dissolved oxygen and aquatic life. Nonetheless, it could be used as an easily available and economical alternative to reduce culture medium costs in microbially induced calcium carbonate precipitation (MICP). In this work, a native Sporosarcina pasteurii was isolated and then cultured by using different proportions of whey (W) in nutrient broth (NB). The solids were characterized by XRD, FT-IR, TGA, and SEM. The potential applications in bioconsolidation were also studied. Whey concentration was directly related to CaCO3 production. Higher whey concentrations reduced calcium carbonate purity to nearly 80%. All experiments showed calcite and vaterite fractions, where a whey increment in the media increased calcite content and decreased vaterite content, causing a decrease in crystal size. MICP improved compressive strength (CS) in sand and fly ash. The best CS results were obtained by fly ash treated with 25 W-75 NB (37.2 kPa) and sand with 75 W-25 NB (32.1 kPa). Whey changed crystal polymorphism in biogenic CaCO3 production. Material bioconsolidation depends on the CaCO3 polymorph, thus fly ash was effectively bioconsolidated by crystallization of vaterite and sand by crystallization of calcite.

Tuning Organic Microcrystal Morphologies through Crystal Engineering Strategies toward Anisotropic Optical Waveguide.

The construction of organic optoelectronic materials with desirable size and morphology remains a challenge now. Crystal engineering strategies (polymorphs and cocrystals) provide convenience for tailoring molecular packing and further controlling the growth morphology and photofunctionality of materials. Herein, we prepare polymorphic 2D plate crystals and 3D microhelixes by assembly of a cyanostilbene derivative (2-(3',5'-bis(trifluoromethyl)-biphenyl-4-yl)-3-(4-(pyridin-4-yl)phenyl)acrylonitrile, CF3-CN-Py). The former emits blue emission, while the latter emits green emission. Different crystallization environments contribute to the adjustable morphologies. Then, novel cocrystals are fabricated with the introduction of 1,4-diiodotetrafluorobenzene (FDIB) to CF3-CN-Py. Both molecular conformation and packing are totally changed in the cocrystal system. Such cocrystal displays a 1D sky-blue emissive rod shape on account of a long-range ordered π-stacking of molecules. In addition, the 2D plate crystal and 1D rod cocrystal are further applied to optical waveguides. In the plate crystal, a packing of transition dipole moment (μ) inclined to the upper surface leads to an anisotropic optical waveguide. In the cocrystal, owing to the nearly horizontal μ orientation, the cocrystal exhibits light propagation along the primary growth direction and a low optical loss coefficient. The present study supplies an effective way to construct materials with controlled morphology and optical waveguide.

Bio-Mediated Soil Improvement Using Plant Derived Enzyme in Addition to Magnesium Ion

Recently, soil improvement using EICP (Enzyme-Induced Carbonate Precipitation) methods in the geotechnical and geo-environmental field has become a prominent interest worldwide. The objective of this study was to develop an improved extraction technique of crude urease from watermelon seeds in both dry and germinated conditions. Subsequently, this study also analyzed the improvement methodology of crystal polymorphs and soil bonding incorporation of various Mg2+/Ca2+ ratios. The optimization of enzyme-mediated carbonate precipitation was also investigated by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Results confirmed that the precipitated crystals are mainly calcite, vaterite and aragonite primarily (depending on the Mg2+/Ca2+ ratios). Therefore, to improve the bonding capacity in between the sand particles a novel improvement methodology was investigated by adding various Mg2+/Ca2+ ratios. The mechanical properties of the treated soil (Mikawa Sand, D50 = 0.870 mm) specimens were tested by unconfined compressive strength (UCS) and this confirmed the effectiveness of adding various Mg2+/Ca2+ ratios. The results of the UCS tests showed that, the lower molar ratios of Mg2+/Ca2+ can significantly improve the UCS of the specimen (up to 50%) which could be considered a significant outcome for different bio-geotechnical applications.

Oleogels of Some Plant Waxes: Characterization and Comparison with Sunflower Wax Oleogel

AbstractThis study aimed to develop the oleogels of tea wax (TWO), rapeseed wax (RWO), orange peel wax (OWO), rose wax (RsWO), and beery wax (BWO), and to compare their properties with sunflower wax oleogel (SWO). Since the literature lacks most of these new oleogels, the gained information would be valuable. The wax oleogels were analyzed for their main physicochemical, thermal, structural, rheological, and sensory properties. The minimum gelation concentrations (C*) ranged from 1.0% (SWO) to 25% (RWO), with gelation times of 0.3–205 min, respectively. While polarized light microscopy images showed large crystal aggregates, X‐ray diffraction patterns proved the presence of β' polymorph crystals and some amorphous solids. Rheological analyses indicated that the samples had a weak‐gel structure, and were stable until around 30–70 °C temperatures. Further, the oleogel samples showed a thixotropic rheological behavior with force‐related recovery at 10 °C. Quantitative sensory descriptive analysis (QDA) proved that there were some differences among the samples for sensory hardness, spreadability, liquefaction, rancid, waxy, and cooling attributes. Also, tea aroma in TWO, bitterness in OWO, and rose aroma in RsWO were quite dominant. In conclusion, RWO and OWO seemed unsuitable for food applications due to very high C* and bitterness, while RsWO and BWO could be used in food formulations.

Ab initio determination of crystal stability of di-p-tolyl disulfide

With the rapid growth of energy demand and the depletion of existing energy resources, the new materials with superior performances, low costs and environmental friendliness for energy production and storage are explored. Di-p-tolyl disulfide (p-Tol2S2) is a typical lubricating material, which has been applied in the field of energy storage. The conformational properties and phase transformations of p-Tol2S2 have been studied by pioneers, but their polymorphs and the polymorphism induced crystal structure changes require further analysis. In this study, we perform the crystal structural screening, prediction and optimization of p-Tol2S2 crystal with quantum mechanical calculations, i.e., density functional theory (DFT) and second-order Møller–Plesset perturbation (MP2) methods. A series of crystal structures with different molecular arrangements are generated based on the crystal structure screening. As compared to long-established lattice energy calculation, we take an advantage of using more accurate technique, which is Gibbs free energy calculation. It considers the effects of entropy and temperature to predict the crystal structures and energy landscape. By comparing the Gibbs free energies between predicted and experimental structures, we found that phase α is the most stable structure for p-Tol2S2 crystal at ambient temperature and standard atmospheric pressure. Furthermore, we provide an efficient method to discriminate different polymorphs that are otherwise difficult to be identified based on the Raman/IR spectra. The proposed work enable us to evaluate the quality of various crystal polymorphs rapidly.

Study on the Regulation of Piracetam Crystallization Behavior

AbstractPowder X‐ray diffraction, scanning electron microscopy, and molecular simulation techniques are used to analyze the crystallization of piracetam under different solvents and different cooling rates. The crystallization of piracetam in methanol system is controlled by thermodynamics, and it is easy to form stable polymorph. The crystallization of piracetam in isopropanol system is controlled by kinetics and forms metastable polymorph. The crystallization of piracetam in the ethanol system is controlled by thermodynamics and kinetics, and the cooling rate affects the formation of the crystal polymorphs, which is easy to be mixed. Dmol3 is used to calculate the energy, electrostatic potential, and frontier orbital energy of piracetam molecules in form II and form III configurations molecules in different systems. The results show that the methanol system is easier to form stable polymorph than the ethanol system.

Structural and kinetic aspects of electron-beam crystallization of amorphous films of antimony sulfide

Electron-beam crystallization of amorphous films of Sb2S3 of both stoichiometric composition and with the excess of Sb was studied by the methods of transmission electron microscopy “in situ” with video registration of structural changes. It was revealed, that Sb2S3 films of stoichiometric composition crystallize polymorphous in a single stage. Films with the excess of Sb crystallize in two stages. There is predominant crystallization of Sb during the first stage of the process, and subsequent crystallization of matrix of Sb2S3 during the second stage. The kinetic curves, demonstrating the dependence on time of the density and size of micro-crystals of Sb, as well as of the dependence on time of the size of Sb2S3 crystals and of fraction of the crystalline phase were obtained with the help of frame-by-frame analysis of the video. Primary crystallization of Sb2S3 occurs in accordance with the layer polymorphous crystallization mode with the relative length δ0 ≈ 4992. The dependence on time of the fraction crystallized has a quadratic character. Secondary crystallization of Sb2S3 occurs also in accordance with the layer polymorphous crystallization mode with the relative length δ0 ≈ 9725. The dependence on time of the fraction crystallized can be described by power function with the exponent 0.68.

Photophysical properties and stimuli-responsive crystal-state luminescence switching of morpholine-modified naphthalic anhydride derivative

Stimuli-response organic solid-state luminescence switching materials are attracting increasing interest due to their smart photophysical properties. In this study, a morpholine-modified naphthalic anhydride derivative, 4-(4-morpholinyl)naphthalic anhydride (MBC), was synthesized and studied. Its two crystal polymorphs, MBC-G and MBC-O, were obtained under different crystallization conditions. These two distinct crystals show significantly different solid-state luminescence behaviors: a green emission at 535 nm for MBC-G, and an orange emission at 572 nm for MBC-O. Upon fiercely grinding the MBC-G crystal or melting and then quickly cooling it, a phase transition occurs from MBC-G to MBC-O, accompanied by a fluorescence change from green to orange. The reverse transformation from MBC-O to MBC-G can be achieved by recrystallization. The X-ray single crystal structures show that the green emission should be attributed to molecular J-aggregation in the crystal packing, and the orange emission may originate from molecular H-aggregation. This switchable color nature gives MBC the promising candidate for potential smart anti-counterfeiting and light-emitting materials.

Particle design of the metastable form of clopidogrel hydrogen sulfate by building spherulitic growth operating spaces in binary solvent systems

Clopidogrel hydrogen sulfate occupies a large market share of antithrombotic drugs. Its metastable form I has the advantages of high solubility and bioavailability. However, the poor powder properties and stability limit its application. This work solved the issue by building spherulitic growth operating space in “isopropyl acetate + lower alcohol” binary solvent systems. The systems were selected by the indicators of solubility and isosteric adsorption heats. By investigating crystal morphologies, polymorph transformation, and gelation with supersaturation gradient experiment, ATR-FTIR spectroscopy, and inverted tube method, these binary solvent systems follow the supersaturation-dependent spherulitic growth mechanism providing operating spaces significantly larger than the reported single solvent system. Hence, an optimal crystallization process was designed to prepare high-quality spherulites of form I avoiding polymorph transformation and gelation. Compared with the reported single solvent system, the optimized product presents better powder properties with residual solvent decreased by 59% and operating time decreased by 75%–90%.

Novel Physics-Based Ensemble Modeling Approach That Utilizes 3D Molecular Conformation and Packing to Access Aqueous Thermodynamic Solubility: A Case Study of Orally Available Bromodomain and Extraterminal Domain Inhibitor Lead Optimization Series

Drug design with patient centricity for ease of administration and pill burden requires robust understanding of the impact of chemical modifications on relevant physicochemical properties early in lead optimization. To this end, we have developed a physics-based ensemble approach to predict aqueous thermodynamic crystalline solubility, with a 2D chemical structure as the input. Predictions for the bromodomain and extraterminal domain (BET) inhibitor series show very close match (0.5 log unit) with measured thermodynamic solubility for cases with low crystal anisotropy and good match (1 log unit) for high anisotropy structures. The importance of thermodynamic solubility is clearly demonstrated by up to a 4 log unit drop in solubility compared to kinetic (amorphous) solubility in some cases and implications thereof, for instance on human dose. We have also demonstrated that incorporating predicted crystal structures in thermodynamic solubility prediction is necessary to differentiate (up to 4 log unit) between solubility of molecules within the series. Finally, our physics-based ensemble approach provides valuable structural insights into the origins of 3-D conformational landscapes, crystal polymorphism, and anisotropy that can be leveraged for both drug design and development.

Oxidant‐Accelerated Polydopamine Modification Process for the Fast Fabrication of PDA on HMX with Improved Mechanical Stability

AbstractPolydopamine surface coating shows the capability to improve the adhesive properties as well as mechanical stabilities of energetic materials, which is highly desired for the development of insensitive munitions. However, the slow polymerization process of dopamine makes the coating process time‐consuming and uneconomic. Herein, an oxidant‐accelerated strategy was demonstrated to obtain fast polymerization kinetics of dopamine for the surface modification of HMX crystals. Upon the addition of oxidant, PDA was able to form surface layer of HMX particles within 5 min without changing the shape and polymorph of HMX crystals. The PDA coating showed the ability to improve the wettability of HMX, contributing to its abundant active groups. Moreover, the mechanical stability of PDA on HMX (HMX@PDA) samples was improved accompany with the increasing coating time, and the friction explosion probability and drop height of 300 s treated sample were 40 % and 64 cm, respectively. The detonation velocity was also measured, which showed that the effect of PDA coating on the detonation velocity of HMX was not significant. More importantly, our protocol showed the capability to fabricate HMX@PDA with different particle sizes on a large scale, satisfying the application demands of insensitive high explosives.

Characterisation of Fat Crystal Polymorphism in Cocoa Butter by Time-Domain NMR and DSC Deconvolution.

The polymorphic state of edible fats is an important quality parameter in fat research as well as in industrial applications. Nowadays, X-ray diffraction (XRD) is the most commonly used method to determine the polymorphic state. However, quantification of the different polymorphic forms present in a sample is not straightforward. Differential Scanning Calorimetry (DSC) is another method which provides information about fat crystallization processes: the different peaks in the DSC spectrum can be coupled to the melting/crystallisation of certain polymorphs. During the last decade, nuclear magnetic resonance (NMR) has been proposed as a method to determine, qualitatively and/or quantitatively, the polymorphic forms present in fat samples. In this work, DSC- and NMR-deconvolution methods were evaluated on their ability to determine the polymorphic state of cocoa butter, with XRD as a reference method. Cocoa butter was subjected to two different temperature profiles, which enforced cocoa butter crystallization in different polymorphic forms. It was found that XRD remains the best method to qualitatively determine the polymorphic state of the fat. Whereas the quantitative NMR and DSC deconvolution results were not fully in line with the XRD results in all cases, NMR deconvolution showed great promise both in a qualitative and quantitative way.

Anomalous structure transition in undercooled melt regulates polymorphic selection in barium titanate crystallization

The crystallization processes of titanates are central to the fabrication of optical and electrical crystals and glasses, but their rich polymorphism is not fully understood. Here, we show when and how polymorphic selection occurs during the crystallization of barium titanate (BaTiO3, BT) using in situ high energy synchrotron X-ray diffraction and ab initio molecular dynamic simulation. An anomalous structure transition is found in molten BT during cooling across the cubic-hexagonal transition temperature, which enables nucleation selection of BT by manipulating the undercooling: a cubic phase is preferred if nucleation is triggered at large undercooling, whereas a hexagonal phase is promoted at small undercooling. We further reveal that the nucleation selection between the cubic and the hexagonal phase is regulated by the intrinsic structure property of the melt, in particular, the degree of polymerization between Ti-O polyhedra. These findings provide an innovative perspective to link the polymorphic crystallization to the non-isomorphic structure transition of the melt beyond the conventional cognition of structural heredity.

Thermodynamic characteristics of L-histidine polymorphs and effect of ethanol on the crystallization

L-Histidine(L-His) has two polymorphs of FormA and FormB. It is known that the crystallization of polymorphs is influenced by antisolvents. In this study, crystal morphology of polymorph was considered from prediction of crystal structures. Next, the effects of ethanol on polymorphs and morphology of L-His were studied by evaluating crystals obtained from saturated aqueous solutions by cooling or adding of ethanol. From the prediction of crystal structures, It is suggested that FormA crystal tend to grow in the long side direction. Experiments show that FormA tends to be obtained from aqueous solvent, on the other hands, FormB tends to be obtained from ethanol existing solution. However, FormB were found to dissolve gradually and transited to FormA. Furthermore, results show high concentration of ethanol change the morphology along its thickness direction, so it suggests that the effect of antisolvents has a big influence on crystallization. Moreover, the results of Thermogravimeter-Differential Thermal Analyzer (TG-DTA) and Differential Scanning Calorimetry (DSC) analysis demonstrate that FormB, which is thought as a metastable form, is possibly favorable in term of thermal stability and suggests the behavior of melting and decomposition of L-His.

Coupling effect of pressure and flow fields on the crystallization of Poly(vinylidene fluoride)/Poly(methyl methacrylate) miscible blends

During polymer processing, the polymeric blends are inevitably subjected to coupled external fields (flow, pressure, and temperature), which have great effects on the phase behavior, crystallization behavior, crystalline structure, and final properties of blends. A typical crystalline/amorphous miscible blend system, poly(vinylidene fluoride)/Poly(methyl methacrylate) (PVDF/PMMA) blend, is chosen to understand the coupling effect of processing fields on crystallization behavior of the blends. It is found that shear flow can induce locally oriented trans conformation, which finally transforms into polar β/γ phases during isothermal crystallization under pressure. Interestingly, under pressure, β and γ phases exhibit different sensitivities to shear rate. The γ phase is easily formed at low shear rate, while higher shear rate is required to induce β phase formation, which could be related to the sequence length of the oriented trans conformation induced by shear flow. As for the addition of PMMA, the hydrogen bonding interactions between carbonyl groups of PMMA and hydrogen atom of PVDF could stabilize the shear-induced local trans conformation and subsequently lead to more β/γ phases. Meanwhile, different from PVDF crystallized under static condition, the shear flow and PMMA synergistically induce the transformation from spherulitic to shish-kebab-like structure and highly oriented thick β phase with higher melting point. To the best of our knowledge, it is the first time to reveal the unique crystallization behaviors of PVDF/PMMA blends induced by flow field coupled with pressure. This work could provide a significant guidance for the control of crystal polymorphs of PVDF/PMMA miscible blends during processing.

Nitro–Nitrito Photoisomerization of Cationic Platinum(II) Complexes in the Solid State: Reactivity in Polymorphic Crystals and Glassy State

Nitro–nitrito isomerization is a well-known photoreaction exhibited by metal complexes in the solid state. We previously reported that the isomerization ratio in the salts of a cationic platinum(II...

Ameliorative Effect of Multi Herbal Formulation on Lipid Peroxidation and Redox Dysfunction in Ethanol Induced Hepatic Imbalance

Abstract: Introduction: Urolithiasis has afflicted human race since the days of yore. Conventional treatment acts only on associated ailments whereas pharmacologically active phytoconstituents derived from plants are reported to possess lithotriptic as well as anti-urolithiatic effect, thus herbal sources need to be scientifically explored. Present study was aimed to evaluate anti-urolithiatic potential of leaves of Alstonia scholaris and its isolated pentacyclic triterpenoids: lupeol and ursolic acid in ethylene glycolinduced renal calculi rat model. Materials and Methods: Leaves of Alstonia scholaris were extracted with various solvents, amount of triterpenoids in each extract was quantified using HPTLC. Extract which had higher amount of triterpenoid was evaluated for its anti-urolithiatic effect. Albino wistar rats of either sex were divided into 6 groups. All groups except vehicle were fed with 0.75%v/v of ethylene glycol for 28 days. Treatment with standard cystone, low and high dose of extract and pentacyclic triterpenoids were given to respective groups from 4th-28th day of study. On 28th day, serum creatinine, uric acid, BUN, TNF-α, IL-6 and urinary electrolyte levels were estimated. Kidneys were isolated, one was used for histopathological study and other for antioxidant assays. Results and Discussion: Histopathological examination of kidneys revealed destructed morphology due to deposition of large polymorphic crystals and cystic dilatation of tubules. Whereas treatment with extract and its pentacyclic triterpenoids prevented renal damage and deposition of crystals. Perturbations in levels of nitrogenous wastes, inflammatory mediators and urinary electrolytes were also prevented. Alstonia scholaris rich in triterpenoid significantly arrested associated oxidative stress and inflammation thus preventing formation of renal calculi. Conclusion: Leaves of Alstonia scholaris and pentacyclic triterpenoids isolated from them demonstrates potent herbal remedy for treatment of urolithiasis. Key words: Alstonia scholaris, Anti-inflammatory, Lupeol, Oxidative stress, Ursolic acid, Urolithiasis.

Insights into Excimer Formation Factors from Detailed Structural and Photophysical Studies in the Solid‐State

AbstractSolid‐state luminescent materials are essential for the development of optoelectronic devices like lasers, sensors, and organic light‐emitting diodes. Organic molecules reveal several benefits like stability, costs, and environmental compatibility compared to metal‐based materials. As common organic fluorophores often suffer from aggregation‐caused quenching, different strategies have been established to overcome this quenching, which are mainly based on intramolecular modifications. Controlling the photophysical properties via intermolecular interactions is more challenging and less investigated. The formation of excited dimers (excimers) bears great potential for obtaining efficient solid‐state luminescent materials. As the excimer‐formation process is strongly dependent on the non‐covalent interactions, a full understanding of the structure–property relationship is essential. In this study, structurally simple thiophosphoranyl anthracene excimers and the dependency of the photophysical properties on the solid‐state arrangement are investigated. Through crystallization of polymorphs and co‐crystals, the resulting intermolecular interactions have been modulated over a broad range. Novel insights into the excimer formation factors and the dependence of the photophysical properties on the intermolecular interactions are obtained. This study will help in the development and controlling the photophysical properties of solid‐state luminescent materials.

Understanding the Salt-Dependent Outcome of Glycine Polymorphic Nucleation.

The salt-dependent polymorphs of glycine crystals formed from bulk solutions have been a longstanding riddle. In this study, in order to shed fresh light, we studied the effects of seven common salts on primary nucleation of the metastable α-glycine and the stable γ-glycine. Our nucleation experiments and in-depth data analyses enabled us to reveal that (NH4)2SO4, NaCl and KNO3, in general, promote γ-glycine primary nucleation very significantly while simultaneously inhibiting α-glycine primary nucleation, thereby explaining why these three salts induce γ-glycine readily. In comparison, Ca(NO3)2 and MgSO4 also promote γ-glycine and inhibit α-glycine primary nucleation but not sufficiently to induce γ-glycine. More interestingly, Na2SO4 and K2SO4 promote not only γ-glycine but also α-glycine primary nucleation, which is unexpected and presents a rare case where a single additive promotes the nucleation of both polymorphs. As a result, the promoting effects of Na2SO4 and K2SO4 on γ-glycine do not enable γ-glycine nucleation to be more competitive than α-glycine nucleation, with γ-glycine failing to appear. These observations help us to better understand salt-governed glycine polymorphic selectivity.

Chiral Polymorphic Hydrazine-based Asymmetric Liquid Crystal Trimers with Resorcinol as Linking Group.

This is the first report on chiral polymorphic hydrazine-based asymmetric liquid crystal trimers, 1-[4'-(4''-(5-Cholesteryloxy)carbonyl)butyloxy]-3-[N-benzylideneoxy-N'-(4'''-decyloxybenzylidene) hydrazine] butyloxybenzenes, and 1-[4'-(4''-(10-cholesteryloxy)carbonyl)nonyloxy]-3-[N-benzylideneoxy-N'-(4'''- decyloxybenzylidene)hydrazine]butyloxybenzenes., in which the hydrazine and cholesterol arms were connected via two flexible methylene spacers (n = 3-12 units and m = 4 or 9, respectively) to the central resorcinol core. FT-IR, 1D and 2D NMR spectroscopy, and CHN microanalysis were used to elucidate the structures of the trimers. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction were used to study the transitional and phase properties of the trimers, which were length and spacer parity dependent. Trimers with short spacer length in the cholesteryl arm, m = 4 showed an interesting phase sequence of BP/N*-TGBA*-SmA*. The TGBA* phase was sensitive to spacer length as it was only observed in trimers with short ester linkage. For the long analogues, m = 9, characteristic visible reflection and a much simpler phase sequence with only N* and SmA* phases were observed. The X-ray diffraction measurements revealed that layer periodicities of the SmA* phase were approximately half the estimated all-trans molecular length (d/L ≈ 0.44-0.52), thus suggesting that the molecules are either strongly intercalated or bent.