Single Crystal Research Articles

Experimental and theoretical studies of a new NLO active organic salt of 2-amino-4-hydroxy-6-methylpyrimidine and 4-hydroxybenzoic acid

The new monohydrate organic salt (AHMPHB) of 2-amino-4-hydroxy-6-methylpyrimidine (AHMP) with 4-hydroxybenzoic acid (HBA) was successfully synthesized and grown as an organic single crystal with characteristic optical quality using the slow evaporation technique (SET). The structural study of the grown crystal was performed using single-crystal XRD. The XRD results revealed that AHMPHB belongs to the triclinic system with space group P-1. Various functional groups of AHMPHB were identified using Raman and FTIR spectroscopic analyses. The optimized geometry and other theoretical results were determined by the DFT/B3LYP method at the 6-311++G(d,p) basis set. The H⋅⋅⋅H and O⋅⋅⋅H intermolecular forces are dominated in the crystal packing and these were explored using Hirshfeld surface and fingerprint plot analyses. TG and DTA studies demonstrate that AHMPHB remains stable up to 140 ºC. According to UV-Vis spectral analysis, AHMPHB has exhibited high transparency in the visible region with a direct band gap of 4.10 eV. The NLO measurement of AHMPHB was done using the Z-scan method. The energy of the HOMO-LUMO gap of 4.37 eV was predicted using DFT calculations. NBO analysis was performed to represent the charge transfer between localized bonds and lone pairs. Moreover, the MEP maps, HOMO-LUMO profiles and theoretical NLO parameters of AHMPHB and its constituents are also obtained.

Investigation on growth, structural, spectral, optical, thermal, third order nonlinear optical and DFT studies of dibenzoylmethane single crystal for photonic and optoelectronic applications

Investigation on growth, structural, spectral, optical, thermal, third order nonlinear optical and DFT studies of dibenzoylmethane single crystal for photonic and optoelectronic applications

Growth and spectroscopy characteristics of Er, Ce:BGSO crystal: A promising material for eye-safe laser applications

Er, Ce co-doped BGSO single crystals were successfully grown by the Bridgman method. The growth parameters, including temperature gradient and growth rate, were optimized to achieve high-quality crystals. The crystal structure and morphology were characterized using X-ray diffraction and scanning electron microscopy. The optical absorption properties of Er, Ce co-doped BGSO single crystals were studied using UV–Vis absorption spectroscopy. The absorption spectrum revealed the absorption edge and the presence of absorption bands related to the presence of Ce dopant, providing valuable insights into the energy transfer processes occurring within the crystal lattice. Furthermore, the luminescence mechanism of BGSO crystals was analyzed using the Judd-Ofelt (J-O) theory, with detailed investigation into the role of ligands in spectral parameters. The photoluminescence spectra and emission decay time of Er, Ce co-doped BGSO single crystals were characterized. A comparative analysis with Er, Ce:BGSO crystals was conducted to investigate the sensitization mechanism of Ce ions on Er emission at 1.5 μm, demonstrating their potential for use as eye-safe laser materials in various applications.

Influence of Ionic Liquids on the Functionality of Optoelectronic Devices Employing CsPbBr3 Single Crystals

Regulating the nucleation temperature and growth rates during inverse temperature crystallization (ITC) is vital for obtaining high-quality perovskite single crystals via this technique. Precise control over these parameters enables growing crystals optimized for various optoelectronic devices. In this study, it is demonstrated that incorporating a 1-butyl-3-methylimidazolium bromide (BMIB) ionic liquid into the precursor solution of cesium lead bromide (CsPbBr3) brings about a dual enhancement effect. This includes a reduction in nucleation temperature from 85 °C to 65 °C and a significant improvement in both optoelectronic characteristics and crystal properties. The CsPbBr3 single crystals grown using ITC with BMIB added (method (2)) demonstrate improved chemical and physical properties (crystallinity, lattice strain, nonradioactive recombination, and trap density) compared to CsPbBr3 single crystals produced through conventional 85 °C ITC alone (method (1)). The exceptional quality of CsPbBr3 single crystals produced with the inclusion of BMIB allowed for the development of a highly responsive optoelectronic device, demonstrating heightened sensitivity to green light. The findings of this investigation reveal that the growth of perovskite single crystals assisted by ionic liquid exerts a substantial impact on the characteristics of the crystals. This influence proves advantageous for the development of optoelectronic devices based on single crystals.

Crystal structure and Hirshfeld surface analysis of pinaverium bromide dihydrate

In the present study, we have discovered and identified a new crystalline form of pinaverium bromide, pinaverium bromide dihydrate (C26H41BrNO4⋅Br⋅2H2O), whose single crystals can be obtained by recrystallization from a mixture of water and acetonitrile at room temperature. The obtained crystals were characterized by X-ray single-crystal diffraction, and their crystal structure was also solved based on X-ray single-crystal diffraction data. The results show that the final pinaverium bromide dihydrate model contains an asymmetric unit of one pinaverium bromide (C26H41Br2NO4) molecule and two water molecules that combine with the bromine ion through O–H⋯O and O–H⋯Br hydrogen bonds. Then, the adjacent pinaverium bromide dihydrates are linked by O–H⋯O, O–H⋯Br, and C–H⋯O hydrogen bonds. On the other hand, the experimentally obtained X-ray powder diffraction pattern is in good agreement with the simulated diffraction pattern from their single-crystal data, confirming the correctness of the crystal structure. Hirshfeld surface analysis was employed to understand and visualize the packing patterns, indicating that the H⋯H interaction is the main acting force in the crystal stacking of pinaverium bromide dihydrate.

Thermal Expansion of Römerite under Low-Temperature Conditions Revision 2

Abstract Römerite, a triclinic hydrous sulfate in the P1 space group with the chemical formula Fe2+Fe3+2 (SO4)4 × 14(H2O), is of potential interest in studies of planetary environments, with particular relevance to Mars and the icy Jovian satellites. Past work has indicated the presence of hydrous sulfates on said bodies and the mixed-valence iron in the structure of römerite makes the mineral a worthwhile end-member composition in thermodynamic models. Such models should be constrained with measurements at the low temperatures relevant to the planetary environments in question. We characterized single crystals of römerite with time-domain Mössbauer spectroscopy, Raman spectroscopy, and X-ray diffraction methods. Through our X-ray diffraction experiment, we refined the unit–cell parameters of the crystal between 100 and 300 K. The resulting temperature-variant lattice parameters and volumes are reported and are fit by physical and empirical models of the thermal expansion coefficient. The physical model considered, a Debye model of thermal expansion, provides estimates of additional thermodynamic parameters: the ratio of the bulk modulus at 0 K and 1 bar to the thermodynamic Grüneisen parameter (K0,0K/γth), the volume at 0 K and 1 bar (V0,0K), and the Debye temperature (θD).

Development of colorimetric probe using robust zinc-MOF and its consistent melamine sponge composite: Instantaneous N3–, La3+ sensing and degradation applications

The crystalline sponge method (CSM), which involves soaking a target molecule into a crystalline metal-organic framework (MOF), offers a promising approach by eliminating the need for high-quality single crystals of the target compound. To broaden the scope of compounds that can be analyzed using CSM, it is essential to investigate various MOFs. In this study, we focused on evaluating the potential of a zinc-based MOF, specifically [Zn3(Cei)2((Bimb)3] (Zinc-MOF), as a CSM host. We successfully synthesized and thoroughly characterized Zinc-MOF. Additionally, we developed a Zinc-MOF@melamine sponge (Zinc-MOF@MS) composite, which exhibited significant photocatalytic activity by degrading hazardous organic dyes such as Rose Bengal (RB) and Crystal Violet (CV), achieving degradation efficiencies of 98.95 % and 92.51 %, respectively, after 120 min of exposure to visible sunlight. The luminescent properties of the Zinc-MOF were also explored, demonstrating strong luminescent emission and excellent chemical stability. Furthermore, Zinc-MOF showed remarkable sensing capabilities, selectively detecting La³⁺ cations and N₃⁻ anions in aqueous solutions through luminescence quenching.

Designing Sustainable Copper‐Based Hybrid Framework Catalysts for One‐Pot Multicomponent Organic Reactions

AbstractThe recent breakthroughs in heterogeneous catalysis emphasize the need for novel materials capable of driving organic transformations. The present study explores two copper phosphonate hybrid framework materials, 2D Cu3[(Hhedp)2(C4H4N2)].2H2O (Cu(II)Pyz‐P) and 3D Cu3[(H3hedp)2(C4H4N2)4(SO4)].2H2O (Cu(I/II)Pyz‐P), as single crystals isolated via hydrothermal synthetic strategy using H4hedp (1‐hydroxyethane 1,1‐diphosphonic acid) and N‐donor secondary ligand (Pyrazine; C4H4N2). Cu(II)Pyz‐P contains exclusively +2 oxidation state of copper, while Cu(I/II)Pyz‐P is characterized by a mixed oxidation state, where copper +2 phosphonate is embedded within the network formed by copper +1 state. Moreover, magnetic study elucidates the distinct oxidation states of both compounds by showing deviations from each other. The aforementioned compounds are exceedingly effective for catalyzing multicomponent reactions, that is, A3 coupling reaction and click reaction. Cu(I/II)Pyz‐P ensures the regioselective synthesis of triazole with high purity, while A3 coupling reaction is facilitated by both the compounds. Solvent‐ and additive‐free efficient multicomponent reactions are explored for the first time in the copper phosphonate hybrid framework structures. The present study reveals the promise of copper‐based hybrid phosphonate frameworks as durable and efficient catalysts for organic synthesis, providing cost‐effective and sustainable ways for advanced catalytic transformations.

Ab initio calculations of second-, third-, and fourth-order partial and inner elastic constants of diamond.

By means of ab initio calculations, a unified framework is presented to investigate the effect of internal displacement on the linear and nonlinear elasticity of single diamond crystals. The calculated linear and nonlinear elastic constants, internal strain tensor and internal displacement in single diamond crystals are compatible with the available experimental data and other theoretical calculations. The complete set of second-, third- and fourth-order elastic constants and internal strain tensor not only offer a better insight into the nonlinear and anisotropic elasticity behaviors, but also shows us the basic internal mechanical response of diamond. This study provides a route to calculate the nonlinear internal and external elasticity response in a nonprimitive lattice.

Usnic Acid Derivatives as Multi-Target Anti-Alzheimer's Disease Agents: Design, Synthesis, X-Ray Single Crystal Structure of Zn(II) Complex and Biological Activities.

Alzheimer's disease (AD) is multifactorial, which makes the design of multi-target-directed ligands an attractive strategy for the development of anti-AD drugs. In order to enhance the anti-AD effects and reduce the toxicity, two usnic acid (UA) derivatives (1-2) were designed, synthesized and fully characterized by introducing dimethylamine Schiff base moiety into the toxic "triketone" portion. Ellman's method and molecular docking were used to test the cholinesterase inhibitory activities. Antioxidant activities were studied with Fenton reaction, cyclic voltammetry and C. elegans. The results showed that compared with UA, 1-2 had stronger anti-cholinesterase activities and similar antioxidant activities. Notably, solvent evaporation of 2 and ZnCl2 formed a single crystal, which was revealed to be a Zn(II) complex with UA and tertiary amine as mixed ligands by X-ray diffraction. The hydrolysis of 2 was thus furtherly studied by HPLC. Furthermore, the crystal structure supported the replacement of toxic "triketone" moiety in the chelation process, playing a detoxifying role and at the same time regulating metal homeostasis. In silico prediction also showed low hepatotoxicity and acceptable drug-likeness of 1-2. Overall, this work provided useful insights into multi-target anti-AD candidates with the natural product UA as the lead compound.

LiLnGeS4 (Ln=La-Nd): Designing High Performance Infrared Nonlinear Optical Sulfides through "Band Reformation of AGS".

AgGaS2 (AGS) is the most commonly used commercial infrared nonlinear optical (IR NLO) material. However, AGS has a narrow band gap (Eg=2.58 eV) and a low laser-induced damage threshold (LIDT), primarily attributed to its mobile liquid-like Ag+ constituent and the unstable Ag-S chemical bond. Herein, we propose a "band reformation of AGS" strategy, which leads to the successful syntheses of four lanthanide sulfides, LiLnGeS4 (Ln=La-Nd), crystalizing in an asymmetric Ama2 structure. LiLaGeS4 demonstrates that eliminating the presence of Ag-4d band increases the Eg to 3.32 eV and enhances the LIDT (14-29×AGS, measured by both powder and single crystal); while increasing the nonbonding density of states of the S-3p band enhances the 2nd-nonlinear optical coefficient (1.06×AGS). Besides, the bond length discrepancy between [LiS4], [GeS4] and [LaS8] units leads to a moderate birefringence (Δn=0.052). Such a unique structure further results in extremely small thermal expansion with αL=0.41-1.74×10-5 K-1, along different crystallographic axes. Our theoretical studies indicate that the synergy of the structure building units contribute to the second harmonic generation performance. These results suggest that the "band reformation of AGS" strategy provides effective guidance to discover new NLO crystals with optimized performance.

Growth, spectroscopy properties, and laser operation of single crystal fiber: Nd3+-doped CNGG

Nd3+-doped calcium niobium gallium garnet single crystal fibers (Nd:CNGG SCFs) with varying Nd3+ concentrations were successfully grown using the laser-heated pedestal growth (LHPG) method. The study thoroughly examines the fundamental physical structure, optical properties, and laser characteristics of the as-grown Nd:CNGG SCFs. Results indicate that the Nd:CNGG SCF exhibits broader absorption and emission full width at half maximum (FWHM) compared to bulk single crystals. Moreover, pumped by a commercial 808 nm laser diode, continuous-wave laser operation at 1061 nm with a half-height width of 1.86 nm was achieved. The laser output power reached 1.04 W at an absorbed power of 7.46 W, with a slope efficiency of 25.4% relative to the absorbed pump power. These findings suggest that Nd:CNGG SCF holds promise as a practical and potent candidate for laser gain medium, offering significant research potential in the field of lasers.

LiLnGeS4 (Ln=La−Nd): Designing High Performance Infrared Nonlinear Optical Sulfides through “Band Reformation of AGS”

AbstractAgGaS2 (AGS) is the most commonly used commercial infrared nonlinear optical (IR NLO) material. However, AGS has a narrow band gap (Eg=2.58 eV) and a low laser‐induced damage threshold (LIDT), primarily attributed to its mobile liquid‐like Ag+ constituent and the unstable Ag−S chemical bond. Herein, we propose a “band reformation of AGS” strategy, which leads to the successful syntheses of four lanthanide sulfides, LiLnGeS4 (Ln=La−Nd), crystalizing in an asymmetric Ama2 structure. LiLaGeS4 demonstrates that eliminating the presence of Ag‐4d band increases the Eg to 3.32 eV and enhances the LIDT (14–29×AGS, measured by both powder and single crystal); while increasing the nonbonding density of states of the S‐3p band enhances the 2nd‐nonlinear optical coefficient (1.06×AGS). Besides, the bond length discrepancy between [LiS4], [GeS4] and [LaS8] units leads to a moderate birefringence (Δn=0.052). Such a unique structure further results in extremely small thermal expansion with αL=0.41–1.74×10−5 K−1, along different crystallographic axes. Our theoretical studies indicate that the synergy of the structure building units contribute to the second harmonic generation performance. These results suggest that the “band reformation of AGS” strategy provides effective guidance to discover new NLO crystals with optimized performance.

CVD‐Synthesized CsAg2I3 Single Crystals toward Polarization UV Photodetection and Anti‐Counterfeiting Identification

AbstractLow‐dimensional ternary silver halide (CsAg2I3), an emerging inorganic lead‐free perovskite, has garnered significant scientific attention due to its strong quantum confinement effects, wide bandgaps, non‐toxicity, and others. However, the photophysical properties and optoelectronic performance of CsAg2I3 materials and devices are significantly compromised by crystal quality and defects arising from liquid‐phase preparation. Herein, 1D CsAg2I3 single crystals newly grown by the chemical vapor deposition method are reported. These crystals display exceptional quality and stability over a 3‐month period despite exposure to air and moisture. The high in‐plane anisotropic structure, phonon vibrations, and refractive index of CsAg2I3 crystals are also experimentally elucidated. Polarization‐sensitive ultraviolet photodetector based on the CsAg2I3 monocrystal features a responsivity of 139 mA W−1, a specific detectivity of 1.05 × 1011 cm Hz1/2 W−1, an ultra‐fast photoresponse speed of 48.2/69.1 µs, and a dichroic ratio of 2.66 upon 360 nm irradiation at −5.0 V bias. The photodetector excels amongst its competitors, moving toward the potential application of rapid optical anti‐counterfeiting identification. This work, which leverages grown high‐crystalline and highly stable CsAg2I3 monocrystals, holds promises for advancing this functional material into a robust next‐generation optoelectronic devices capable of probing sensitive optical sensing and specific azimuth recognition.

Machine learning assisted crystallographic reconstruction from atom probe tomographic images

Atom probe tomography (APT) is a powerful technique for three-dimensional (3D) atomic-scale imaging, enabling the accurate analysis on the compositional distribution at the nanoscale. How to accurately reconstruct crystallographic information from APT data, however, is still a great challenge due to the intrinsic nature of the APT technique. In this paper, we propose a novel approach that consists of the modified forward simulation process and the backward machine learning process to recover the tested crystal from APT data. The high-throughput forward simulations on Al single crystals of different orientations generate 10 000 original 3D images and data augmentation is implemented on the original images, resulting in 100 000 3D images. The big data allows the development of deep learning models and three deep learning algorithms of Convolutional Neural Network (CNN), Vision Transformer (ViT), and Variational Autoencoder (VAE) are used in the backward process. After training, the ViT model performs superior than the CNN and VAE models, which can recover the crystalline orientation outstandingly, as evaluated by the coefficient of determinationR2and the Mean Percent Error (MPE), viz.,R2= 0.93 and MPE = 0.43%,R2= 0.97 and MPE = 0.35%, andR2= 0.93 and MPE = 0.77% for the rotation anglesϕ,ψandθ, respectively, on the test dataset. The present work clearly demonstrates the capability of deep learning models in the recovery of the tested crystals from APT data, thereby paving the way for the further development of large artificial intelligent models of APT.

The Reversible Gel to Gel Transition of a Phosphonocarboxylate Functionalized Strandberg‐Type Polyoxometalate System

AbstractThe Strandberg polyoxometalate (POM) metallogel Na4(H3O)2[(O2CC2H4PO3)2Mo5O15] (1) was synthesized in which the Strandberg cluster is functionalized by phosphonocarboxylate. The POM gel shows reversible sol to gel transition and gel to gel transition. The multiphase visual transitions between three states as a function of temperature and solvent are scarcely reported. The gel is characterized by temperature‐dependent and frequency‐dependent rheological studies and corresponding xerogels were characterized by FT‐IR, PXRD, FE‐SEM, EDX, TEM, and 31P NMR techniques. The stabilization of gel or obtaining single crystals from the same reaction mixture can be tuned by choice of counter cation. The single crystals of compound Cs14[(HO2CC2H4PO3)2Mo5O15]3·2Cl·10H2O (2) are obtained on addition of CsCl to compound 1 reaction mixture. Compound 2 is characterized by single crystal X‐ray diffraction. The compound 2 crystallizes in I2/a space group with unit cell parameters of a = 24.2415(16) Å, b = 10.4542(6) Å, c = 42.687(3) Å, α = 90°, β = 94.791°(3), and γ = 90°.

Growing a single suspended perfect protein crystal in a fully noncontact manner

Nucleation is a fundamental process that determines the structure, morphology, and properties of crystalline materials, and is difficult to control because it is unpredictable. Here, we demonstrate a new method to control the protein crystal nucleation using a magnetic force, where we manipulate the movement and coalescence of nucleation precursors by adding paramagnetic salt into the crystallization solution to constrain the number and position of nucleation. We found that protein nucleation could be significantly affected by the magnetic force that the gradient magnetic fields generate. When the magnetization force is sufficiently enough, nucleation can be confined to the crystallization solution with no interface contact; therefore, only one crystal nucleus appears, which results in noncontact suspension growth of a single crystal in the crystallization solution system. Under these situations, the nucleation rate significantly decreases due to the coalescence of the dense liquid phase, and the crystal growth rate also decreases due to the suppression of convection, which increases the crystal quality. Our findings provide a new method for the noncontact control of crystal nucleation and demonstrate that externally applied physical environments can be used to affect the liquid-liquid phase separation process.

A comparative study of X-ray structural analysis, supramolecular investigation by Hirshfeld surface analysis and DFT computations for tricyclic 1,4-benzodiazepines

The tricyclic 1,4-benzodiazepines - seven-membered heterocyclic compounds were synthesized derived from the three-component reaction involving o-phenylenediamine, 5,5-dimethyl-1,3-cyclohexanedione and various aromatic aldehydes under the influence of HCl. The crystal structure of 11-(3-nitrophenyl)-3,3-dimethyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one (NDDD) and 11-(2-chlorophenyl)-3,3-dimethyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one (CDDD) corroborated through single crystal X-ray diffraction method. The Hirshfeld surface analysis indicates crystal packing along with role of intermolecular forces in stabilizing supramolecular assembly of NDDD and CDDD. 2D fingerprint analysis is carried out to envisage to the elemental interactions in the assumption of a single crystal containing molecular fragments. DFT investigations have been carried out to understand the reactivity of NDDD and CDDD at the m062x/def2tzvp method. The obtained geometric parameters from theoretical study are well consistent with experimentally reported XRD analysis. Bonding analysis and charge transfer were examined by performing quantum theory of atoms in molecules (QTAIM) and natural bonding orbital (NBO) analysis. The synthesized NDDD and CDDD exhibit excellent electronic and nonlinear optical properties. The NLO response is justified through computed hyperpolarizability values.

Warm-White Light Emission of Lead-free CsAg2I3 Single Crystal Scintillator with a One-Dimensional Electronic Structure.

Presently, the exploration of novel inorganic lead-free perovskite scintillators has emerged as a prominent topic in the field of perovskite materials. Extensive attention has been garnered by materials such as Cs3Cu2I5 due to their notable advantage in scintillation intensity, but the response time constants in the microsecond or even millisecond range severely constrain their potential applications in scintillators. In this study, large-sized (5-6 mm) CsAg2I3 single crystals with an ultrafast warm-white light emission on a nanosecond time scale are presented. Specifically, upon X-ray excitation, the single crystal demonstrates a broad-spectrum white light emission with a color temperature as high as 5129 K, attributed to its self-trapped exciton emission. The 137Cs energy spectrum reveals that CsAg2I3 possesses an ultrafast response for γ rays with a time constant of 15 ns, which is significantly faster than that of Cs3Cu2I5. Furthermore, time-resolved photoluminescence unveils a subnanosecond component with a response time of 0.9 ns. The characteristics of ultrafast warm-white light emission exhibit the significant potential of CsAg2I3 in radiation scintillation detection and its probability of playing a pivotal role in future radiation detection technology.

Synthesis and structure of a non-van-der-Waals two-dimensional coordination polymer with superconductivity

Two-dimensional conjugated coordination polymers exhibit remarkable charge transport properties, with copper-based benzenehexathiol (Cu-BHT) being a rare superconductor. However, the atomic structure of Cu-BHT has remained unresolved, hindering a deeper understanding of the superconductivity in such materials. Here, we show the synthesis of single crystals of Cu3BHT with high crystallinity, revealing a quasi-two-dimensional kagome structure with non-van der Waals interlayer Cu-S covalent bonds. These crystals exhibit intrinsic metallic behavior, with conductivity reaching 103 S/cm at 300 K and 104 S/cm at 2 K. Notably, superconductivity in Cu3BHT crystals is observed at 0.25 K, attributed to enhanced electron-electron interactions and electron-phonon coupling in the non-van der Waals structure. The discovery of this clear correlation between atomic-level crystal structure and electrical properties provides a crucial foundation for advancing superconductor coordination polymers, with potential to revolutionize future quantum devices.