High-pressure β-Sn germanium may transform into diverse metastable allotropes with distinctive nanostructures and unique physical properties via multiple pathways under decompression.However,the mechanism and transit...High-pressure β-Sn germanium may transform into diverse metastable allotropes with distinctive nanostructures and unique physical properties via multiple pathways under decompression.However,the mechanism and transition kinetics remain poorly understood.Here,we investigate the formation of metastable phases and nanostructures in germanium via controllable transition pathways of β-Sn Ge under rapid decompression at different rates.High-resolution transmission electron microscopy reveals three distinct metastable phases with the distinctive nanostructures:an almost perfect st12 Ge crystal,nanosized bc8/r8 structures with amorphous boundaries,and amorphous Ge with nanosized clusters (0.8–2.5 nm).Fast in situ x-ray diffraction and x-ray absorption measurements indicate that these nanostructured products form in certain pressure regions via distinct kinetic pathways and are strongly correlated with nucleation rates and electronic transitions mediated by compression rate,temperature,and stress.This work provides deep insight into the controllable synthesis of metastable materials with unique crystal symmetries and nanostructures for potential applications.展开更多
Herein,a first example of energetic-energetic cocrystal polymorphs with a 1:1 M ratio was discovered by cocrystallizing CL-20(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane)with 1,3-DNP(1,3-dinitropyrazole...Herein,a first example of energetic-energetic cocrystal polymorphs with a 1:1 M ratio was discovered by cocrystallizing CL-20(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane)with 1,3-DNP(1,3-dinitropyrazole).These two energetic cocrystal polymorphs(cocrystal 1 and cocrystal 2)exhibit distinct crystal packing styles,which lead to significant variations in their physicochemical properties.Notably,cocrystal 2 has a high density of 1.963 g·cm^(-3)at 170 K,exhibiting high detonation performances(9187 m·s^(-1);38.68 GPa)comparable to HMX(1,3,5,7-tetranitro-1,3,5,7-tetrazocane)meanwhile displaying an improved safety(10 J)relative to RDX(1,3,5-trinitro-1,3,5-triazinane),making it a potential high-energy,low-sensitivity energetic material.This work opens up a new strategy to deeply tune properties of energetic materials by constructing energetic-energetic cocrystal polymorphs.These energetic cocrystal polymorphs represent a new field of energetic materials that has not yet been studied.展开更多
Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline p...Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline polymorph is an intriguing phenomenon that the presence of multiple packing and aggregate architectures of the same molecular system.The studies on polymorphs for molecule-based fluorophores provide the opportunities to adjust the mode of molecular packing and photophysical properties,which will help to illustrate the structure-property relationship.In this review,we focus on the recent progress in various feasible methods of molecule-based crystalline polymorphism growth and their adjustable photofunctional properties,which will open up possibilities of variant optical applications.Firstly,several effective ways to prepare and screen polymorphs are sorted out.And then,we discuss the discrepant properties and multifunctional applications(such as sensors,laser and OFET).Finally,the development trends and future prospects of these polymorphs are also briefly introduced.展开更多
In the present study,Form I,Form II and Form III of agomelatine were prepared to investigate the variability of polymorphs,then the in-vitro in-vivo correlation were established.The presence of three polymorphs of ago...In the present study,Form I,Form II and Form III of agomelatine were prepared to investigate the variability of polymorphs,then the in-vitro in-vivo correlation were established.The presence of three polymorphs of agomelatine was corroborated through studies by XRPD,TGA and DSC.All the forms obtained were then subjected to the powder and intrinsic dissolution tests.The IDR ranked in the order of Form III>Form I>Form II.Form I and Form III both underwent solvent-mediated phase transformation(SMPT)to Form II during dissolution and the transition points were 62 and 45 min,respectively.Pharmacokinetic profiles were acquired after oral administration of tablets,showing that the ka and AUC0e12 h of Form I,Form II,Form III were 0.580.11,0.340.05,0.740.07 h1 and 296.2549.39,186.0545.93,331.1654.74 ng*h/ml,respectively.Good linearities between IDR and ka,IDR and AUC were established,suggesting that the agomelatine polymorphic forms with faster dissolution rates in-vitro would increase the rate and extent of oral absorption in-vivo.These results demonstrated that IDR was predictive in estimating the relative bioavailability of agomelatine polymorphic forms.展开更多
The recently discovered tetragonal, monoclinie and orthorhombic polymorphs of M3N4 （M=C, Si, Sn） are in- vestigated by using first-principles calculations. A set of anisotropic elastic quantities, i.e., the bulk and...The recently discovered tetragonal, monoclinie and orthorhombic polymorphs of M3N4 （M=C, Si, Sn） are in- vestigated by using first-principles calculations. A set of anisotropic elastic quantities, i.e., the bulk and shear moduli, Young＇s modulus, Poisson ratio, H/G ratio and rickets hardness of M3N4 （M=C, Si, Sn） are predicted. The quasi-harmonic Debye model, assuming that the solids are isotopic, may lead to large errors for the non-cubic crystals. The thermal effects are obtained by the traditional quasi-harmonic approach. The dependences of heat capacity, thermal expansion coefficient and Debye temperature on temperature and pressure are systematically discussed in the pressure range of 0 IOGPa and in the temperature range of 0-1100 K. More importantly, o- C3N4 is a negative thermal expansion material. Our results may have important consequences in shaping the understanding of the fundamental properties of these binary nitrides.展开更多
Calcium carbonate (CaCO3) occurs in the three polymorphs calcite, aragonite and vaterite. The formation of these crystals in inorganic solutions is influenced by parameters like pH, temperature or impurities. Living f...Calcium carbonate (CaCO3) occurs in the three polymorphs calcite, aragonite and vaterite. The formation of these crystals in inorganic solutions is influenced by parameters like pH, temperature or impurities. Living freshwater microalgae can also induce the formation of CaCO3 when they live in a suitable environment containing saturated amounts of Ca2+. Through this biologically induced biomineralization only the formation of the polymorph calcite has been reported yet. We investigated the precipitates which have been formed in solutions containing the freshwater microalgae Scenedesmus obliquus and different zinc amounts (0, 3.27 and 6.53 mg Zn2+/l) by XRD and SEM. As references precipitates from the same solutions but without algae were investigated. We could show that the presence of living microalgae has a great influence on the precipitation of calcium carbonate crystals. In algae-containing media without or with a low zinc amount always calcite and aragonite are formed. In the corresponding medium with 6.53 mg Zn2+/l pure aragonite crystals were built. In contrast, in the inorganic, algae-free solutions without zinc, pure calcite is precipitated. Both inorganic solutions with zinc show major calcite precipitation and weak aragonite precipitation. Thus the algae cells advance significantly the formation of aragonite, which is enhanced by the presence of zinc cations in the media. Possible mechanisms are discussed.展开更多
Flupirtine maleate, a pharmaceutical compound for treating psychotic disease in clinics, has seven polymorphs. Form A, with better crystal stability and bioavailability, has been widely used as the pharmaceutical crys...Flupirtine maleate, a pharmaceutical compound for treating psychotic disease in clinics, has seven polymorphs. Form A, with better crystal stability and bioavailability, has been widely used as the pharmaceutical crystal form. Unfortunately, it is usually found in a polymorphic mixture with form B. In this study, pure crystal forms of A and B were prepared and characterized by X-ray powder diffraction （XRPD）, Fourier transform infrared spectroscopy （FT-IR） and thermal analysis. An XRPD-based method for the quantitative determination of the amount of the flupirtine maleate polymorphs form A and form B was also established through a systematic optimization of instrumental parameters. The results of the analytical methodology validation showed that the XPRD method had a broad quantitative range of 0- 100% （w/w）, good linear relationship, with R2= 0.999, excellent repeatability and precision and low limits of detection （LoD） of 0.15% （w/w） and quantification （LoQ） of 0.5% （w/w）. The results also showed that the single-peak method was not as good as the whole pattern in reducing the influence of the preferred orientation, but this can be compensated for by a systematic optimization of instrumental parameters and validating the analytical methodology to reduce errors and obtain a good, repeatable, sensitive, and accurate method. This XRPD method can be used to analyze mixtures of flupirtine maleate polymorphs （forms A and B） quantitatively and control the quality of the bulk drug.展开更多
α-PbO2-type TiO2 （TiO2-Ⅱ） is an important index mineral for ultrahigh-pressure metamorphism. After the discovery of a natural high-pressure phase of titanium oxide with α-PbO2- structure in omphacite from coesite...α-PbO2-type TiO2 （TiO2-Ⅱ） is an important index mineral for ultrahigh-pressure metamorphism. After the discovery of a natural high-pressure phase of titanium oxide with α-PbO2- structure in omphacite from coesite-bearing eclogite at Shima in the Dabie Mountains, China, a nanoscale （〈2 nm） α-PbO2-type TiO2 has been identified through electron diffraction and high-resolution transmission electron microscopy in coesite-bearing jadeite quartzite at Shuanghe in the Dabie Mountains. The crystal structure is orthorhombic with lattice parameters a = 4.58×10-1 nm, b = 5.42×10-1 nm, c = 4.96×10-1 nm and space group Pbcn. The analysis results reveal that ruffle {011}R twin interface is a basic structural unit of α-PbO2-type TiO2. Nucleation of α-PbO2-type TiO2 lamellae is caused by the displacement of one half of the titanium cations within the {011}R twin slab. This displacement reduces the Ti-O-Ti distance and is favored by high pressure. The identification of α- PbO2-type TiO2 in coesite-bearing jadeite quartzite from Shuanghe, Dabie Mountains, provides a new and powerful evidence of ultrahigh-pressure metamorphism at 4--7 GPa, 850℃-900℃, and implies a burial of continental crustal rocks to 130-200 kilometers depth or deeper. The α-PbO2-type TiO2 may be a useful indicator of the pressure and temperature in the diamond stability field.展开更多
As a quite ubiquitous phenomenon,crystal polymorph is one of the key issues in the field of organic semiconductors.This review gives a brief summary to the advances on polymorph control of thin film and single crystal...As a quite ubiquitous phenomenon,crystal polymorph is one of the key issues in the field of organic semiconductors.This review gives a brief summary to the advances on polymorph control of thin film and single crystal of representative organic semiconductors towards high-performance field-effect transistors.Particularly,the relationship between crystal polymporh and charge transport behaviour has been discussed to shed light on the rational preparation of outstanding organic semiconducting materials with desired crystal polymorph.展开更多
The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent t...The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.展开更多
Mangiferin is a compound with many pharmacological activities and exists in many natural products.Anhydrous and hydrate of mangiferin have been reported separately in two literatures,but the polymorphism of this compo...Mangiferin is a compound with many pharmacological activities and exists in many natural products.Anhydrous and hydrate of mangiferin have been reported separately in two literatures,but the polymorphism of this compound has not been realized until this paper.In this study,polymorph screening of mangiferin has been carried out and five forms have been obtained including three new forms never reported.Several solid state characterization methods,such as powder X-ray diffraction,differential scanning calorimetry and thermogravimetry,are used to identify and characterize all of mangiferin forms.The comparison of the crystallographic data and hirshfeld surface analysis were first reported for mangiferin anhydrous and hydrate.Furthermore,the studies on stability,transformation and solubility have been undertaken,the results prompt that form V can be used as the dominant polymorph for the development of innovative pharmaceuticals.展开更多
Polymorphism is a common phenomenon in nature.Here,we report one-pot wet chemical method to synthesize two polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) nanocluster protected by 1-adamantanethiol(HSAdm),which adopt P-1 and ...Polymorphism is a common phenomenon in nature.Here,we report one-pot wet chemical method to synthesize two polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) nanocluster protected by 1-adamantanethiol(HSAdm),which adopt P-1 and P2_(1)/c space group respectively.The crystal structures of two polymorphs were determined by X-ray crystallography.Compared to the previously reported Au_(19)Ag_(4)(S-Adm)_(15)nanocluster adopting P2_(1)/n space group,polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) with P-1 and P2_(1)/c space group show the different optical properties.Moreove r,Au_(19)Ag_(4)(S-Adm)_(15) with P-1 space group exhibits good thermal stability.Meanwhile,we investigated the effect of solvent and molar ratio of metal precursors on the polymorphs.This work provides an insight to polymorphs of metal nanoclusters.展开更多
3’,4’-Dimethoxy-flavonol-3-O-β-D-glucopyranoside monohydrate(GDH),which can significantly reduce blood lipids,atherosclerotic aortic lesions,and liver injury,has poor oral bioavailability.In the present study,we ai...3’,4’-Dimethoxy-flavonol-3-O-β-D-glucopyranoside monohydrate(GDH),which can significantly reduce blood lipids,atherosclerotic aortic lesions,and liver injury,has poor oral bioavailability.In the present study,we aimed to prepare and characterize five new polymorphs of GDH(II,III,IV,V,and VI)and the amorphous form of GDH(GDH-AM).The GDH polymorphs and GDH-AM were characterized by scanning electron microscopy(SEM),differential scanning calorimetry(DSC),thermogravimetric analysis(TGA),X-ray powder diffraction(XRPD),and Fourier transform infrared spectroscopy(FTIR).Dissolution tests,physical stability,polymorphic transformation,and permeability studies were subsequently investigated.Dissolution of GDH-II and GDH-IV reached higher concentrations compared with GDH-I.GDH-AM exhibited a significantly high dissolution rate and prolonged supersaturation during dissolution.No phase transition was found for GDH-I and GDH-AM after 3 months of storage,while GDH-II,GDH-III,GDH-IV,GDH-V,and GDH-VI were readily converted to GDH-I.In situ single-pass intestinal perfusion experiments showed that the high concentration of GDH exhibited low permeability.Sodium dodecyl sulfate and bovine bile salts were used as absorption enhancers to improve the permeability of GDH.The results showed that sodium dodecyl sulfate and taurocholate were good absorption enhancers for further formulation development of GDH.展开更多
Three polymorphs(forms I,II and V)of isonicotinamide(INA)were mechanically flexible and exhibited one-dimensional(1 D)plasticity.Anisotropic intermolecular interactions contribute to the plasticity of single crystals:...Three polymorphs(forms I,II and V)of isonicotinamide(INA)were mechanically flexible and exhibited one-dimensional(1 D)plasticity.Anisotropic intermolecular interactions contribute to the plasticity of single crystals:weak dispersive interactions between slip planes such as 1 D columns in forms I and II or 2 D layers in form V were stabilized by strong hydrogen bonds,allowing the layer or column's surface to glide smoothly without hindrance.The disparity of intermolecular interactions on plastic properties of INA polymorphic crystals was confirmed by energy framework analysis,nanoindentation tests and micro-Raman spectroscopy.The crystal which exhibits plastic property provides a promising application in pharmaceuticals and material sciences.展开更多
The precise control of active pharmaceutical ingredient(API)crystal nucleation and polymorphism is a key consideration in pharmaceutical manufacturing.In this study,tunable nanoparticles were developed to regulate the...The precise control of active pharmaceutical ingredient(API)crystal nucleation and polymorphism is a key consideration in pharmaceutical manufacturing.In this study,tunable nanoparticles were developed to regulate the nucleation process of coumarin.Magnetic silica nanoparticles with four different functional groups(-NH_(2),-COOH,-SH,-NCO)were prepared and coated on the substrate for inducing the crystallization of coumarin.Confined melt crystallization and microspacing sublimation crystallization methods were used to investigate the regulation mechanism.The results indicated that three metastable forms of coumarin can be obtained as pure components based on the combined influence of crystallization methods and functionalized nanoparticles.FormⅡcould be selectively obtained by microspacing sublimation crystallization on Fe_(3)O_(4)@SiO_(2)-SH substrates,and FormⅣcould be obtained by confined melt crystallization on Fe_(3)O_(4)@SiO_(2)-NCO substrates.FormⅢcould be obtained by further heating FormⅣcrystals to 52℃on Fe_(3)O_(4)@SiO_(2)-NCO substrates.Moreover,the polarized light microscopy results also indicated that the introduction of nanoparticles could also increase the stability of the metastable crystalline forms of coumarin.Finally,the diffusion and surface dynamics during nanoparticle induced crystallization were comparatively investigated and the corresponding polymorphic selectivity mechanism was proposed.展开更多
Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2）...Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2） A, at = 67.045（1）,β = 77.845（1）, γ= 88.762（1）°, V = 2830.43（7） A3, Z = 4, R = 0.0491, wR= 0.1276; Polymorph 2： tetragonal P43, a = b = 13.53690（1） A, c = 30.8491（8） A, V = 5653.02（16） A3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystal structures, the hydrogen-bonded ribbons built of 4,4＇-dihydroxybenzophenone （DHBP, C13H1003） anions and water molecules are orderly arranged to generate two-dimensional host layers, with tetrabutylammonium cations contained between the layers to form the sandwich-like inclusion compounds. The structures of 1 and 2, which exist as two polymorphs, both display the similar packing pattern and hydrogen-bond linking model.展开更多
Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding a...Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding and the complexity of the networks they form pose significant challenges to computational studies of ice structures.In this work,we present an extensive exploration of ice polymorphs under pressure conditions ranging from 1 bar to 10 GPa.We employ an advanced crystal-structure-prediction scheme that integrates an evolutionary algorithm,an active-learning deep neural network potential,and molecular dynamics simulations with ab initio accuracy.Among the 131,481 predicted structures,we successfully identify all experimentally known ice phases within the target pressure range,including the particularly challenging ice IV and V.These phases feature highly intricate H-bond networks,which have hindered previous efforts to fully explore ice structures.Additionally,we identify 34 new ice polymorphs that are potential candidates for experimental discovery.Notably,we predict the existence of a new stable ice phase,ice L,within the temperature range of 253–291 K and pressure range of 0.38–0.57 GPa,exhibiting a unique topology unseen in any known crystals.Our findings highlight the potential for experimental discovery of new ice phases.Furthermore,our approach can be applied to other complex systems,particularly those with network structures.展开更多
Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by ...Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by the fine-tuning thermal-reduction treatment of cobalt phosphonates with spherical shape,the novel carbon-wrapped CoP-Co_(2)P polymorphs are rationally constructed.The unique hierarchical porous architecture and heterointerface of CoP-Co_(2)P not only increase active sites but also ensure intrinsic activity.The resultant catalyst exhibits significantly boosted HER activity in a wide pH range,for instance,a current density of 10 mA cm^(-2) at the overpotential of 81 mV in 0.5 mol L^(-1) H_(2)SO_(4),109 mV in 1.0 mol L^(-1) KOH,and 227 mV in 1.0 mol L^(-1) phosphate buffer saline,and remarkable OER activity(1.53 V@10 mA cm^(-2) in 1.0 mol L^(-1) KOH),associated with the impressive stability for each reaction.Moreover,serving as the bifunctional electrocatalysts in a two-electrode electrolyzer for overall water splitting,a low cell voltage of 1.60 V can deliver a current density of 10 mA cm^(-2) in 1.0 mol L^(-1) KOH.The structural evolution process of the CoP-Co_(2)P catalyst during electrolysis is thoroughly investigated.This work presents a new approach for designing and fabricating efficient and affordable metal phosphides for various electrochemical technologies.展开更多
It is a common phenomenon for organic semi- conductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tun...It is a common phenomenon for organic semi- conductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molec- ular crystal polymorphs （i.e., adjusting the same molecule with different packing arrangements in solid state） towards efficient charge transport and high performance devices. Here, the choice of solvent had a marked effect on con- trolling the growth of a-phase ribbon and β-phase platelet during crystallization for an indenofluorene （IF） π-extended tetrathiafulvalene （TTF）-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the a-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic semiconductors.展开更多
By the combination of the isolated P2O7 dimers and Mg O4 tetrahedra,α-andβ-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method.α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space g...By the combination of the isolated P2O7 dimers and Mg O4 tetrahedra,α-andβ-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method.α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space group P212121,whileβ-Rb2Mg3(P2O7)2 crystallizes in centrosymmetric P21/c.Both structures contain a three dimensional[Mg3P4O14]^2- anionic framework,while Rb^+ cations are in the space.Structure analyses show that the isolated P2O7 dimers can easily adjust their variable configurations and orientations to fit the different coordination environments of the cations,which is conducive to the formation of polymorphs.The phase transformation process fromα-toβ-Rb2Mg3(P2O7)2 was further investigated by powder X-ray diffraction and thermal gravimetric/differential scanning calorimetry measurements.In addition,UV-vis-NIR diffusion spectra indicate both materials have deep-ultraviolet cut-off edges(below 190 nm).α-Rb2Mg3(P2O7)2 is second-harmonic generation(SHG)-active and the origin of SHG response was investigated by the SHG density calculations.The first-principle calculations were also carried out to illuminate their structure-property relationships.展开更多
基金supported by the National Nature Science Foundation of China(NSFC)(Grant No.11974033)Xuqiang Liu acknowledges support from the National Postdoctoral Foundation Project of China under Grant No.GZC20230215+2 种基金the National Nature Science Foundation of China under Grants No.12404001The XRD measurements at room and high temperatures were performed at the 4W2 HPStation of the Beijing Synchrotron Radiation Facility(BSRF)and beamline 15U1 of the Shanghai Synchrotron Radiation Facility(SSRF)In situ high-pressure,low-temperature XRD measurements were conducted at sector 16 ID-B,HPCAT of the Advanced Photon Source,and were supported by DOE-NNSA under Award No.DE-NA0001974.
文摘High-pressure β-Sn germanium may transform into diverse metastable allotropes with distinctive nanostructures and unique physical properties via multiple pathways under decompression.However,the mechanism and transition kinetics remain poorly understood.Here,we investigate the formation of metastable phases and nanostructures in germanium via controllable transition pathways of β-Sn Ge under rapid decompression at different rates.High-resolution transmission electron microscopy reveals three distinct metastable phases with the distinctive nanostructures:an almost perfect st12 Ge crystal,nanosized bc8/r8 structures with amorphous boundaries,and amorphous Ge with nanosized clusters (0.8–2.5 nm).Fast in situ x-ray diffraction and x-ray absorption measurements indicate that these nanostructured products form in certain pressure regions via distinct kinetic pathways and are strongly correlated with nucleation rates and electronic transitions mediated by compression rate,temperature,and stress.This work provides deep insight into the controllable synthesis of metastable materials with unique crystal symmetries and nanostructures for potential applications.
基金support for this study by the National Natural Science Foundation of China(Grant No.22275175)。
文摘Herein,a first example of energetic-energetic cocrystal polymorphs with a 1:1 M ratio was discovered by cocrystallizing CL-20(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane)with 1,3-DNP(1,3-dinitropyrazole).These two energetic cocrystal polymorphs(cocrystal 1 and cocrystal 2)exhibit distinct crystal packing styles,which lead to significant variations in their physicochemical properties.Notably,cocrystal 2 has a high density of 1.963 g·cm^(-3)at 170 K,exhibiting high detonation performances(9187 m·s^(-1);38.68 GPa)comparable to HMX(1,3,5,7-tetranitro-1,3,5,7-tetrazocane)meanwhile displaying an improved safety(10 J)relative to RDX(1,3,5-trinitro-1,3,5-triazinane),making it a potential high-energy,low-sensitivity energetic material.This work opens up a new strategy to deeply tune properties of energetic materials by constructing energetic-energetic cocrystal polymorphs.These energetic cocrystal polymorphs represent a new field of energetic materials that has not yet been studied.
基金supported by the National Natural Science Foundation of China(Nos.21771021 and 21822501)the Beijing Nova Program(No.xx2018115)+1 种基金the Fundamental Research Funds for the Central UniversitiesAnalytical and Measurements Fund of Beijing Normal University
文摘Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline polymorph is an intriguing phenomenon that the presence of multiple packing and aggregate architectures of the same molecular system.The studies on polymorphs for molecule-based fluorophores provide the opportunities to adjust the mode of molecular packing and photophysical properties,which will help to illustrate the structure-property relationship.In this review,we focus on the recent progress in various feasible methods of molecule-based crystalline polymorphism growth and their adjustable photofunctional properties,which will open up possibilities of variant optical applications.Firstly,several effective ways to prepare and screen polymorphs are sorted out.And then,we discuss the discrepant properties and multifunctional applications(such as sensors,laser and OFET).Finally,the development trends and future prospects of these polymorphs are also briefly introduced.
基金The authors acknowledge the financial support received from the National Science and Technology Major Projects for Major New Drugs Innovation and Development of China(No.2009ZX09501-022).
文摘In the present study,Form I,Form II and Form III of agomelatine were prepared to investigate the variability of polymorphs,then the in-vitro in-vivo correlation were established.The presence of three polymorphs of agomelatine was corroborated through studies by XRPD,TGA and DSC.All the forms obtained were then subjected to the powder and intrinsic dissolution tests.The IDR ranked in the order of Form III>Form I>Form II.Form I and Form III both underwent solvent-mediated phase transformation(SMPT)to Form II during dissolution and the transition points were 62 and 45 min,respectively.Pharmacokinetic profiles were acquired after oral administration of tablets,showing that the ka and AUC0e12 h of Form I,Form II,Form III were 0.580.11,0.340.05,0.740.07 h1 and 296.2549.39,186.0545.93,331.1654.74 ng*h/ml,respectively.Good linearities between IDR and ka,IDR and AUC were established,suggesting that the agomelatine polymorphic forms with faster dissolution rates in-vitro would increase the rate and extent of oral absorption in-vivo.These results demonstrated that IDR was predictive in estimating the relative bioavailability of agomelatine polymorphic forms.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61475132 and 61501392
文摘The recently discovered tetragonal, monoclinie and orthorhombic polymorphs of M3N4 （M=C, Si, Sn） are in- vestigated by using first-principles calculations. A set of anisotropic elastic quantities, i.e., the bulk and shear moduli, Young＇s modulus, Poisson ratio, H/G ratio and rickets hardness of M3N4 （M=C, Si, Sn） are predicted. The quasi-harmonic Debye model, assuming that the solids are isotopic, may lead to large errors for the non-cubic crystals. The thermal effects are obtained by the traditional quasi-harmonic approach. The dependences of heat capacity, thermal expansion coefficient and Debye temperature on temperature and pressure are systematically discussed in the pressure range of 0 IOGPa and in the temperature range of 0-1100 K. More importantly, o- C3N4 is a negative thermal expansion material. Our results may have important consequences in shaping the understanding of the fundamental properties of these binary nitrides.
文摘Calcium carbonate (CaCO3) occurs in the three polymorphs calcite, aragonite and vaterite. The formation of these crystals in inorganic solutions is influenced by parameters like pH, temperature or impurities. Living freshwater microalgae can also induce the formation of CaCO3 when they live in a suitable environment containing saturated amounts of Ca2+. Through this biologically induced biomineralization only the formation of the polymorph calcite has been reported yet. We investigated the precipitates which have been formed in solutions containing the freshwater microalgae Scenedesmus obliquus and different zinc amounts (0, 3.27 and 6.53 mg Zn2+/l) by XRD and SEM. As references precipitates from the same solutions but without algae were investigated. We could show that the presence of living microalgae has a great influence on the precipitation of calcium carbonate crystals. In algae-containing media without or with a low zinc amount always calcite and aragonite are formed. In the corresponding medium with 6.53 mg Zn2+/l pure aragonite crystals were built. In contrast, in the inorganic, algae-free solutions without zinc, pure calcite is precipitated. Both inorganic solutions with zinc show major calcite precipitation and weak aragonite precipitation. Thus the algae cells advance significantly the formation of aragonite, which is enhanced by the presence of zinc cations in the media. Possible mechanisms are discussed.
基金supported by the Major Program of Ministry of Science and Technology of China(No:2015ZX09J15104-003002)
文摘Flupirtine maleate, a pharmaceutical compound for treating psychotic disease in clinics, has seven polymorphs. Form A, with better crystal stability and bioavailability, has been widely used as the pharmaceutical crystal form. Unfortunately, it is usually found in a polymorphic mixture with form B. In this study, pure crystal forms of A and B were prepared and characterized by X-ray powder diffraction （XRPD）, Fourier transform infrared spectroscopy （FT-IR） and thermal analysis. An XRPD-based method for the quantitative determination of the amount of the flupirtine maleate polymorphs form A and form B was also established through a systematic optimization of instrumental parameters. The results of the analytical methodology validation showed that the XPRD method had a broad quantitative range of 0- 100% （w/w）, good linear relationship, with R2= 0.999, excellent repeatability and precision and low limits of detection （LoD） of 0.15% （w/w） and quantification （LoQ） of 0.5% （w/w）. The results also showed that the single-peak method was not as good as the whole pattern in reducing the influence of the preferred orientation, but this can be compensated for by a systematic optimization of instrumental parameters and validating the analytical methodology to reduce errors and obtain a good, repeatable, sensitive, and accurate method. This XRPD method can be used to analyze mixtures of flupirtine maleate polymorphs （forms A and B） quantitatively and control the quality of the bulk drug.
文摘α-PbO2-type TiO2 （TiO2-Ⅱ） is an important index mineral for ultrahigh-pressure metamorphism. After the discovery of a natural high-pressure phase of titanium oxide with α-PbO2- structure in omphacite from coesite-bearing eclogite at Shima in the Dabie Mountains, China, a nanoscale （〈2 nm） α-PbO2-type TiO2 has been identified through electron diffraction and high-resolution transmission electron microscopy in coesite-bearing jadeite quartzite at Shuanghe in the Dabie Mountains. The crystal structure is orthorhombic with lattice parameters a = 4.58×10-1 nm, b = 5.42×10-1 nm, c = 4.96×10-1 nm and space group Pbcn. The analysis results reveal that ruffle {011}R twin interface is a basic structural unit of α-PbO2-type TiO2. Nucleation of α-PbO2-type TiO2 lamellae is caused by the displacement of one half of the titanium cations within the {011}R twin slab. This displacement reduces the Ti-O-Ti distance and is favored by high pressure. The identification of α- PbO2-type TiO2 in coesite-bearing jadeite quartzite from Shuanghe, Dabie Mountains, provides a new and powerful evidence of ultrahigh-pressure metamorphism at 4--7 GPa, 850℃-900℃, and implies a burial of continental crustal rocks to 130-200 kilometers depth or deeper. The α-PbO2-type TiO2 may be a useful indicator of the pressure and temperature in the diamond stability field.
基金financial support from the Ministry of Science and Technology of China(Nos.2013CB933504,2014CB643600,2015CB856502)the National Natural Science Foundation of China(Nos.91222203,51303185,21473222)+1 种基金the Strategic Priority Research Program(No.XDB12000000)the Youth Innovation Promotion Association(Chinese Academy of Sciences)
文摘As a quite ubiquitous phenomenon,crystal polymorph is one of the key issues in the field of organic semiconductors.This review gives a brief summary to the advances on polymorph control of thin film and single crystal of representative organic semiconductors towards high-performance field-effect transistors.Particularly,the relationship between crystal polymporh and charge transport behaviour has been discussed to shed light on the rational preparation of outstanding organic semiconducting materials with desired crystal polymorph.
文摘The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.
基金support from Key National Research and Development Programmes(Grant No.2016YFC1000905)the Drug Innovation Major Project(Grant No.2018ZX09711001-001-013)+2 种基金the National Natural Science Foundation of China(Grant No.81703473)the Drug Innovation Major Project(Grant No.2018ZX09711001-010,2017ZX09101001003)CAMS Innovation Found for Medical Sciences(Grant No.2016-I2M-1-007).
文摘Mangiferin is a compound with many pharmacological activities and exists in many natural products.Anhydrous and hydrate of mangiferin have been reported separately in two literatures,but the polymorphism of this compound has not been realized until this paper.In this study,polymorph screening of mangiferin has been carried out and five forms have been obtained including three new forms never reported.Several solid state characterization methods,such as powder X-ray diffraction,differential scanning calorimetry and thermogravimetry,are used to identify and characterize all of mangiferin forms.The comparison of the crystallographic data and hirshfeld surface analysis were first reported for mangiferin anhydrous and hydrate.Furthermore,the studies on stability,transformation and solubility have been undertaken,the results prompt that form V can be used as the dominant polymorph for the development of innovative pharmaceuticals.
基金the National Natural Science Foundation of China(No.21601178)。
文摘Polymorphism is a common phenomenon in nature.Here,we report one-pot wet chemical method to synthesize two polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) nanocluster protected by 1-adamantanethiol(HSAdm),which adopt P-1 and P2_(1)/c space group respectively.The crystal structures of two polymorphs were determined by X-ray crystallography.Compared to the previously reported Au_(19)Ag_(4)(S-Adm)_(15)nanocluster adopting P2_(1)/n space group,polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) with P-1 and P2_(1)/c space group show the different optical properties.Moreove r,Au_(19)Ag_(4)(S-Adm)_(15) with P-1 space group exhibits good thermal stability.Meanwhile,we investigated the effect of solvent and molar ratio of metal precursors on the polymorphs.This work provides an insight to polymorphs of metal nanoclusters.
文摘3’,4’-Dimethoxy-flavonol-3-O-β-D-glucopyranoside monohydrate(GDH),which can significantly reduce blood lipids,atherosclerotic aortic lesions,and liver injury,has poor oral bioavailability.In the present study,we aimed to prepare and characterize five new polymorphs of GDH(II,III,IV,V,and VI)and the amorphous form of GDH(GDH-AM).The GDH polymorphs and GDH-AM were characterized by scanning electron microscopy(SEM),differential scanning calorimetry(DSC),thermogravimetric analysis(TGA),X-ray powder diffraction(XRPD),and Fourier transform infrared spectroscopy(FTIR).Dissolution tests,physical stability,polymorphic transformation,and permeability studies were subsequently investigated.Dissolution of GDH-II and GDH-IV reached higher concentrations compared with GDH-I.GDH-AM exhibited a significantly high dissolution rate and prolonged supersaturation during dissolution.No phase transition was found for GDH-I and GDH-AM after 3 months of storage,while GDH-II,GDH-III,GDH-IV,GDH-V,and GDH-VI were readily converted to GDH-I.In situ single-pass intestinal perfusion experiments showed that the high concentration of GDH exhibited low permeability.Sodium dodecyl sulfate and bovine bile salts were used as absorption enhancers to improve the permeability of GDH.The results showed that sodium dodecyl sulfate and taurocholate were good absorption enhancers for further formulation development of GDH.
基金sponsored by National Key R&D Program of China(No.2016YFC1000900)National Science and Technology Major Project of China(No.2018ZX09711001-001-013)National Natural Science Foundation of China(No.81703438)。
文摘Three polymorphs(forms I,II and V)of isonicotinamide(INA)were mechanically flexible and exhibited one-dimensional(1 D)plasticity.Anisotropic intermolecular interactions contribute to the plasticity of single crystals:weak dispersive interactions between slip planes such as 1 D columns in forms I and II or 2 D layers in form V were stabilized by strong hydrogen bonds,allowing the layer or column's surface to glide smoothly without hindrance.The disparity of intermolecular interactions on plastic properties of INA polymorphic crystals was confirmed by energy framework analysis,nanoindentation tests and micro-Raman spectroscopy.The crystal which exhibits plastic property provides a promising application in pharmaceuticals and material sciences.
基金financial support from the National Natural Science Foundation of China(21908159)the Tianjin Natural Science Foundation(18JCZDJC38100)。
文摘The precise control of active pharmaceutical ingredient(API)crystal nucleation and polymorphism is a key consideration in pharmaceutical manufacturing.In this study,tunable nanoparticles were developed to regulate the nucleation process of coumarin.Magnetic silica nanoparticles with four different functional groups(-NH_(2),-COOH,-SH,-NCO)were prepared and coated on the substrate for inducing the crystallization of coumarin.Confined melt crystallization and microspacing sublimation crystallization methods were used to investigate the regulation mechanism.The results indicated that three metastable forms of coumarin can be obtained as pure components based on the combined influence of crystallization methods and functionalized nanoparticles.FormⅡcould be selectively obtained by microspacing sublimation crystallization on Fe_(3)O_(4)@SiO_(2)-SH substrates,and FormⅣcould be obtained by confined melt crystallization on Fe_(3)O_(4)@SiO_(2)-NCO substrates.FormⅢcould be obtained by further heating FormⅣcrystals to 52℃on Fe_(3)O_(4)@SiO_(2)-NCO substrates.Moreover,the polarized light microscopy results also indicated that the introduction of nanoparticles could also increase the stability of the metastable crystalline forms of coumarin.Finally,the diffusion and surface dynamics during nanoparticle induced crystallization were comparatively investigated and the corresponding polymorphic selectivity mechanism was proposed.
文摘Two polymorphs of the inclusion compound [（n-C4H9）4N]＋＇（C13H903）H2O have been prepared and characterized by X-ray crystallography. Polymorph 1： triclinic P1, a = 13.4982（2）, b = 13.5743（2）, c = 17.1996（2） A, at = 67.045（1）,β = 77.845（1）, γ= 88.762（1）°, V = 2830.43（7） A3, Z = 4, R = 0.0491, wR= 0.1276; Polymorph 2： tetragonal P43, a = b = 13.53690（1） A, c = 30.8491（8） A, V = 5653.02（16） A3, Z = 8, R = 0.0448, wR = 0.0984. In these two crystal structures, the hydrogen-bonded ribbons built of 4,4＇-dihydroxybenzophenone （DHBP, C13H1003） anions and water molecules are orderly arranged to generate two-dimensional host layers, with tetrabutylammonium cations contained between the layers to form the sandwich-like inclusion compounds. The structures of 1 and 2, which exist as two polymorphs, both display the similar packing pattern and hydrogen-bond linking model.
基金supported by the National Natural Science Foundation of China(grant nos.12374217,92370118,and 22003050)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(grant no.2024-ZD-01)+2 种基金the Fundamental Research Funds for the Central Universities,China.The calculations were supported by the National Supercomputing Center in Xi’an,Chinathe BohriumCloud platformat DP technologythe International Center for Materials Discovery(ICMD)cluster of NPU。
文摘Ice,a ubiquitous substance in nature,exhibits diverse forms under varying temperature and pressure conditions.However,our understanding of ice polymorphs remains incomplete.The directional nature of hydrogen bonding and the complexity of the networks they form pose significant challenges to computational studies of ice structures.In this work,we present an extensive exploration of ice polymorphs under pressure conditions ranging from 1 bar to 10 GPa.We employ an advanced crystal-structure-prediction scheme that integrates an evolutionary algorithm,an active-learning deep neural network potential,and molecular dynamics simulations with ab initio accuracy.Among the 131,481 predicted structures,we successfully identify all experimentally known ice phases within the target pressure range,including the particularly challenging ice IV and V.These phases feature highly intricate H-bond networks,which have hindered previous efforts to fully explore ice structures.Additionally,we identify 34 new ice polymorphs that are potential candidates for experimental discovery.Notably,we predict the existence of a new stable ice phase,ice L,within the temperature range of 253–291 K and pressure range of 0.38–0.57 GPa,exhibiting a unique topology unseen in any known crystals.Our findings highlight the potential for experimental discovery of new ice phases.Furthermore,our approach can be applied to other complex systems,particularly those with network structures.
基金supported by the National Natural Science Foundation of China(21875118,22179065 and 22111530112)。
文摘Exploring cobalt phosphide catalysts with abundant active sites and outstanding intrinsic activity for active and robust hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is highly desirable.Herein,by the fine-tuning thermal-reduction treatment of cobalt phosphonates with spherical shape,the novel carbon-wrapped CoP-Co_(2)P polymorphs are rationally constructed.The unique hierarchical porous architecture and heterointerface of CoP-Co_(2)P not only increase active sites but also ensure intrinsic activity.The resultant catalyst exhibits significantly boosted HER activity in a wide pH range,for instance,a current density of 10 mA cm^(-2) at the overpotential of 81 mV in 0.5 mol L^(-1) H_(2)SO_(4),109 mV in 1.0 mol L^(-1) KOH,and 227 mV in 1.0 mol L^(-1) phosphate buffer saline,and remarkable OER activity(1.53 V@10 mA cm^(-2) in 1.0 mol L^(-1) KOH),associated with the impressive stability for each reaction.Moreover,serving as the bifunctional electrocatalysts in a two-electrode electrolyzer for overall water splitting,a low cell voltage of 1.60 V can deliver a current density of 10 mA cm^(-2) in 1.0 mol L^(-1) KOH.The structural evolution process of the CoP-Co_(2)P catalyst during electrolysis is thoroughly investigated.This work presents a new approach for designing and fabricating efficient and affordable metal phosphides for various electrochemical technologies.
基金supported by Beijing NOVA Programme(Z131101000413038)Beijing Local College Innovation Team Improve Plan(IDHT20140512)+2 种基金the National Natural Science Foundation of China(91433115,91222203,91233205 and 51222306)the Ministry of Science and Technology of China(2013CB933403 and 2013CB933504)the University of Copenhagen
文摘It is a common phenomenon for organic semi- conductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molec- ular crystal polymorphs （i.e., adjusting the same molecule with different packing arrangements in solid state） towards efficient charge transport and high performance devices. Here, the choice of solvent had a marked effect on con- trolling the growth of a-phase ribbon and β-phase platelet during crystallization for an indenofluorene （IF） π-extended tetrathiafulvalene （TTF）-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the a-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic semiconductors.
基金financially supported by the National Natural Science Foundation of China (51972230, 51802217, 61835014, 51890864 and 51890865)the Natural Science Foundation of Tianjin (19JCZDJC38200)the National Key Research and Development Project (2016YFB0402103)
文摘By the combination of the isolated P2O7 dimers and Mg O4 tetrahedra,α-andβ-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method.α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space group P212121,whileβ-Rb2Mg3(P2O7)2 crystallizes in centrosymmetric P21/c.Both structures contain a three dimensional[Mg3P4O14]^2- anionic framework,while Rb^+ cations are in the space.Structure analyses show that the isolated P2O7 dimers can easily adjust their variable configurations and orientations to fit the different coordination environments of the cations,which is conducive to the formation of polymorphs.The phase transformation process fromα-toβ-Rb2Mg3(P2O7)2 was further investigated by powder X-ray diffraction and thermal gravimetric/differential scanning calorimetry measurements.In addition,UV-vis-NIR diffusion spectra indicate both materials have deep-ultraviolet cut-off edges(below 190 nm).α-Rb2Mg3(P2O7)2 is second-harmonic generation(SHG)-active and the origin of SHG response was investigated by the SHG density calculations.The first-principle calculations were also carried out to illuminate their structure-property relationships.
