Advanced Structural Crystals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Chemistry chemistry	2.1	2.5	2019	19.1 Days	CHF 1800
Compounds compounds	-	-	2021	20.6 Days	CHF 1000
Crystals crystals	2.7	3.6	2011	10.6 Days	CHF 2600
Materials materials	3.4	5.2	2008	13.9 Days	CHF 2600
Molecules molecules	4.6	6.7	1996	14.6 Days	CHF 2700

13 pages, 3173 KiB

Open AccessArticle

A Least Squares Fitting Method for Uncertain Parameter Estimation in Solidification Model

by Yuhan Wang and Zhi Xie

Crystals 2023, 13(12), 1673; https://doi.org/10.3390/cryst13121673 - 11 Dec 2023

Viewed by 715

This study proposes an automated method for estimating the uncertain parameters of the solidification model in response to the inefficient and time-consuming problem of manually estimating multiple uncertain parameters of the solidification model. The method establishes an uncertain parameter estimation model based on [...] Read more.

This study proposes an automated method for estimating the uncertain parameters of the solidification model in response to the inefficient and time-consuming problem of manually estimating multiple uncertain parameters of the solidification model. The method establishes an uncertain parameter estimation model based on the relationship between the simulated images equiaxed crystal ratio and the uncertain parameters of the solidification model, fits the parameters of the model by the least squares method, and finally estimates the uncertain parameters in the solidification model using the parameters of the fitted model. In comparison with the traditional method of calculating uncertain parameters manually through empirical formulas, this method reduces the difficulty of tuning parameters and solves the problem of tuning multiple parameters simultaneously in the nonlinear solidification model. The experimental results show that the proposed method can accurately estimate the uncertain parameters of the solidification model, improve the efficiency and accuracy of the solidification model estimation parameters, and play a guiding role in simulating the solidification process of continuously casting billet to control the solidification structure. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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11 pages, 2895 KiB

Open AccessArticle

Investigation of the Processes of Structure Formation during Explosion Welding of Copper and Molybdenum

by Fedor M. Noskov, Lyudmila I. Kveglis, Vyacheslav I. Mali, Maksim A. Esikov and Rimma Y. Sakenova

Crystals 2023, 13(10), 1514; https://doi.org/10.3390/cryst13101514 - 19 Oct 2023

Viewed by 765

Abstract

This article examines the processes of structure formation occurring during joint plastic deformation by the explosion of copper and molybdenum. These components are dissimilar metals with very limited mutual solubility under normal conditions, and the circumstances allowing for their interaction, as well as [...] Read more.

This article examines the processes of structure formation occurring during joint plastic deformation by the explosion of copper and molybdenum. These components are dissimilar metals with very limited mutual solubility under normal conditions, and the circumstances allowing for their interaction, as well as the products of the mechanochemical reactions of such interactions, have not been sufficiently studied and require new approaches. A cluster approach was used to describe the processes of structure formation, which describes phase formation as the process transitioning of the polyhedron of the initial phase into the polyhedron of the final phase. This work shows that under the conditions under consideration, not only is the formation of solid solutions in the contact zone with smooth concentration transitions from one component to another possible, but also the formation of new structural states, which can be represented as localized icosahedral atomic configurations (amorphous metal clusters). Such a structure is capable of locally strengthening the composite, which is confirmed by microhardness studies. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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12 pages, 2058 KiB

Open AccessArticle

ab Initio DFT and MD Simulations Serving as an Anchor for Correcting Melting Curves Reported by DAC and SW Experiments—Some Transition Metals as Illustrative Examples

by Joseph Gal

Crystals 2023, 13(8), 1263; https://doi.org/10.3390/cryst13081263 - 16 Aug 2023

Cited by 1 | Viewed by 640

Abstract

The pressure–temperature scales in DAC and shock wave (SW) experiments should be corrected by taking into account the thermal pressure shifts. In the present contribution, it is further claimed that first-principle ab initio DFT and MD simulations should serve as an anchor for [...] Read more.

The pressure–temperature scales in DAC and shock wave (SW) experiments should be corrected by taking into account the thermal pressure shifts. In the present contribution, it is further claimed that first-principle ab initio DFT and MD simulations should serve as an anchor for correcting the pressures and temperatures reported by DAC and SW experiments. It was concluded that upon deriving the actual pressure sensed by the explored sample, the thermal pressure and the temperature shifts must be taken into account when constructing melting curves. Therefore, melting curves measured by diamond anvil cells for 3d elements do not contribute to a better understanding of the geophysical Earth’s inner core. In addition, the advantage of the Lindemann–Gilvarry vs. Simon–Glatzel fitting procedure of melting curves is shown. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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15 pages, 2880 KiB

Open AccessArticle

Topological Design of Two-Dimensional Phononic Crystals Based on Genetic Algorithm

by Xiaodong Wen, Lei Kang, Xiaowei Sun, Ting Song, Liangwen Qi and Yue Cao

Materials 2023, 16(16), 5606; https://doi.org/10.3390/ma16165606 - 13 Aug 2023

Cited by 1 | Viewed by 913

Abstract

Phononic crystals are a kind of artificial acoustic metamaterial whose mass density and elastic modulus are periodically arranged. The precise and efficient design of phononic crystals with specific bandgap characteristics has attracted increasing attention in past decades. In this paper, an improved adaptive [...] Read more.

Phononic crystals are a kind of artificial acoustic metamaterial whose mass density and elastic modulus are periodically arranged. The precise and efficient design of phononic crystals with specific bandgap characteristics has attracted increasing attention in past decades. In this paper, an improved adaptive genetic algorithm is proposed for the reverse customization of two-dimensional phononic crystals designed to maximize the relative bandwidth at low frequencies. The energy band dispersion relation and transmission loss of the optimal structure are calculated by the finite-element method, and the effective wave-attenuation effect in the bandgap range is verified. This provides a solution for the custom-made design of acoustic metamaterials with excellent low-frequency bandgap sound insulation or other engineering applications. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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12 pages, 4206 KiB

Open AccessEditor’s ChoiceArticle

Structure and Thermal Stability of Two Estetrol Solvates

by Magda Monari, Emanuele Attolino, Gianfranco Lopopolo, Fabrizio Bosco and Massimo Gazzano

Crystals 2023, 13(8), 1211; https://doi.org/10.3390/cryst13081211 - 05 Aug 2023

Viewed by 955

Abstract

Two solvates of estetrol have been isolated and characterized by SCXRD and PXRD as well as by thermal analyses, morphology and spectroscopy. Estetrol monohydrate (Estetrol.H₂O, S.G. P1, Z = 12) contains 12 molecules in its asymmetric unit with very subtle conformational [...] Read more.

Two solvates of estetrol have been isolated and characterized by SCXRD and PXRD as well as by thermal analyses, morphology and spectroscopy. Estetrol monohydrate (Estetrol.H₂O, S.G. P1, Z = 12) contains 12 molecules in its asymmetric unit with very subtle conformational differences with one another but reveals an intricate network made of intermolecular H-bonds established with the neighbour estetrol molecules and with crystallization water. Each molecule of estetrol methanol hemisolvate (Estetrol.0.5CH₃OH, S.G. C2, Z = 4) establishes six O-H…O bonds with six different neighbours and additional H-bonds with methanol. In both structures, estetrol molecules are organized in a head-to-tail arrangement that favours the formation of O-H…O interactions. The increased thermal stability of Estetrol.0.5CH₃OH crystals with respect to Estetrol.H₂O can be correlated to the strengthened network of H-bonds. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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16 pages, 3052 KiB

Open AccessArticle

The Influence of Ni Addition in the Mechanism of CO₂ Electroreduction on Cu Crystals—Mechanistic Insight from DFT Simulations

by Elżbieta Dziadyk-Stopyra, Ionut Tranca, Daniel Smykowski and Bartłomiej M. Szyja

Materials 2023, 16(14), 5138; https://doi.org/10.3390/ma16145138 - 21 Jul 2023

Viewed by 748

Abstract

We present a DFT analysis of the role of the Cu-Ni synergistic effect for the CO₂ reduction to C₂H₄, in comparison to the pure Cu catalyst. The analysis is focused on the thermodynamic stability of reactive intermediates along [...] Read more.

We present a DFT analysis of the role of the Cu-Ni synergistic effect for the CO₂ reduction to C₂H₄, in comparison to the pure Cu catalyst. The analysis is focused on the thermodynamic stability of reactive intermediates along the proposed pathway of C₂ species formation. We have observed that the potential needed for the reaction decreases with the addition of Ni in the investigated model. In addition, we have observed the differences in the preferred pathway based on the significant differences in stability of the reactive intermediates depending on th Cu:Ni ratio. The results suggest that despite the fact the Cu surface is always exposed, and it is the only one that is able to directly interact with the intermediates, the presence of the Ni in the underlying sections of the crystal is significant enough to change the mechanism of the reaction. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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13 pages, 2912 KiB

Open AccessArticle

C_{2} O

Nanotubes with Negative Strain Energies and Improvements of Thermoelectric Properties via N-Doping Predicted from First-Principle Calculations

by Jianbao Wu, Liyuan Jiang, Xiaoyi Li and Zhixiang Yin

Crystals 2023, 13(7), 1097; https://doi.org/10.3390/cryst13071097 - 13 Jul 2023

Viewed by 630

Abstract

In this study, the geometric structure, strain energy, and electronic properties of armchair

C_{2} O

nanotubes

(A_C_{2} O N T s (n, n))

and zigzag

C_{2} O

nanotubes [...] Read more.

In this study, the geometric structure, strain energy, and electronic properties of armchair

C_{2} O

nanotubes

(A_C_{2} O N T s (n, n))

and zigzag

C_{2} O

nanotubes

(Z_C_{2} O N T s (n, 0))

are studied in detail. The results show that these nanotubes behave as special shapes; the section of

Z_C_{2} O N T s (n, 0)

along the axial direction is an n-edge type, and the section tends to be round with an increase in n while the boundary of section along the axial direction for

A_C_{2} O N T s (n, n)

fluctuates. With an increase in n, the fluctuation disappears gradually, and the section also tends to be round. Compared with

C_{2} O

nanosheets (

g_C_{2} O

),

C_{2} O

nanotubes have similar or even smaller strain energy, when the tube diameter is greater than or equal to 15

Å

, the strain energy begins to show a negative value, and the negative value tends to be stable as the pipe diameter increases.

Z_C_{2} O N T s

start to show negative strain energies from n = 8 and

A_C_{2} O N T s

from n = 12, indicating their higher stabilities relative to

the g_C_{2} O

sheets. The calculation of the electronic band structure shows that

Z_C_{2} O N T s

are an indirect band gap semiconductor, and

A_C_{2} O N T

is a direct band gap semiconductor. The band gap value of

Z_C_{2} O N T s

first increases and then stabilizes with the diameters of the nanotubes, and the band gap value of

A_C_{2} O N T s

decreases with the increase in the nanotubes and tends to the band gap value of the

g_C_{2} O

sheet. In addition, the electronic properties and thermoelectric properties of

C_{2} O N T s (n = 4, 6, 8)

before and after N-doping were also studied. We found that N-doping changed the electronic and thermoelectric properties of

C_{2} O N T s

. It reduced the nanotube band gap value and significantly improved the thermoelectric figures of merit of

Z_C_{2} O N T s (n = 4, 6, 8)

and

A_C_{2} O N T (4, 4)

, which comprised an effective strategy to improve the thermoelectric figure of merit of nanotubes. The results showed that the

C_{2} O N T s

had potential as thermoelectric materials after N-doping, which provided important guidance for designing low-dimensional

g_C_{2} O

nanostructures. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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16 pages, 3685 KiB

Open AccessEditor’s ChoiceArticle

The Multi-Analytical Characterization of Calcium Oxalate Phytolith Crystals from Grapevine after Treatment with Calcination

by Gwenaëlle Trouvé, Laure Michelin, Damaris Kehrli, Ludovic Josien, Séverinne Rigolet, Bénédicte Lebeau and Reto Gieré

Crystals 2023, 13(6), 967; https://doi.org/10.3390/cryst13060967 - 18 Jun 2023

Cited by 1 | Viewed by 1485

Abstract

Calcium oxalate phytoliths are one of the most prominent types of Ca speciation in the plant kingdom, and they store extensive amounts of carbon in crystalline form. Ca phytoliths were investigated in the root, trunk, and bark of Vitis vinifera Chasselas from a [...] Read more.

Calcium oxalate phytoliths are one of the most prominent types of Ca speciation in the plant kingdom, and they store extensive amounts of carbon in crystalline form. Ca phytoliths were investigated in the root, trunk, and bark of Vitis vinifera Chasselas from a vineyard in Alsace, France. A multi-analytical approach was used, which included SEM coupled with EDX spectroscopy, XRD, XRF, TGA, and ¹³C-NMR spectroscopy. These techniques revealed that phytoliths are composed of crystalline calcium oxalate monohydrate (whewellite). The whewellite crystals exhibited mostly equant or short-prismatic habits in all of the three studied grapevine parts, but bipyramidal crystals also occurred. Raphide crystals were only observed in the root, where they were abundant. Instead of using wet chemical procedures to extract the mineral components from the organic parts of the biomass, a thermal treatment via calcination was chosen. The suitable temperature of calcination was determined through TGA experiments. The calcination of the biomass samples at 250 °C enhanced the amounts of Ca phytoliths in the residual chars. The thermal treatment, however, affected the appearance of the Ca oxalate crystals by producing surfaces that displayed macroporosity and by creating fractures. For calcination at both 300 °C and 350 °C, Ca oxalate lost a molecule of carbon monoxide to form Ca carbonate, and the modifications of the original crystal surfaces were more pronounced than those observed after thermal treatment at 250 °C. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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12 pages, 3577 KiB

Open AccessArticle

Active Control Topological Valley Modes in Metamaterial Plates

by Jingxuan Zhou, Jie Zhang, Jiahui Chang, Zheng-Yang Li and Dongjia Yan

Crystals 2023, 13(6), 933; https://doi.org/10.3390/cryst13060933 - 10 Jun 2023

Cited by 3 | Viewed by 1183

Abstract

Phononic crystals and metamaterials have a unique band structure that allows for the existence of topologically protected surface states. The topologically protected edge states can guide elastic waves without significant scattering or loss of energy. One of the most promising applications of topological [...] Read more.

Phononic crystals and metamaterials have a unique band structure that allows for the existence of topologically protected surface states. The topologically protected edge states can guide elastic waves without significant scattering or loss of energy. One of the most promising applications of topological insulators in wave guiding is in the field of acoustics, where they can be used to design highly efficient and robust acoustic wave guides. However, the high efficiency, precision, reconfigurability, and robustness of elastic waves remains challenging. The topological insulators provide a feasible method to design high-efficiency, robust, and low-backscattering waveguides. In this work, a novel design of hexagonal metamaterial plates composed of a base plate and piezoelectric patches is proposed. The hexagonal metamaterial plate can generate robust topologically protected edge waves via active control. The paths of the topologically protected edge waves can be tuned by adjusting the control parameters. The robustness and efficiency of the proposed hexagonal metamaterial plate are testified to by the numerical examples. These findings provide systematic theoretical guidelines for designing reconfigurable wave guides, elastic wave splitters, and novel elastic wave devices and hold great promise for the development of high-performance and versatile wave guide technologies with potential applications in a wide range of fields. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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27 pages, 9934 KiB

Open AccessArticle

Physico-Chemical Characterization, DFT Modeling and Biological Activities of a New Zn (II) Complex Containing Melamine as a Template

by Thouraya Salah, Noureddine Mhadhbi, Ali Ben Ahmed, Besma Hamdi, Najeh Krayem, Mohamed Loukil, Ahlem Guesmi, Lotfi Khezami, Ammar Houas, Naoufel Ben Hamadi, Houcine Naïli and Ferdinando Costantino

Crystals 2023, 13(5), 746; https://doi.org/10.3390/cryst13050746 - 29 Apr 2023

Cited by 3 | Viewed by 1428

Abstract

Single crystals of a new organic–inorganic hybrid compound (C₃H₇N₆)₂[ZnCl₄]·H₂O was synthesized and characterized by X-ray diffraction at room temperature, FT-IR and FT-Raman spectroscopies, optical absorption and photoluminescence behavior. The title compound [...] Read more.

Single crystals of a new organic–inorganic hybrid compound (C₃H₇N₆)₂[ZnCl₄]·H₂O was synthesized and characterized by X-ray diffraction at room temperature, FT-IR and FT-Raman spectroscopies, optical absorption and photoluminescence behavior. The title compound belongs to the triclinic space group P

\bar{1},

and in the crystal structure, the inorganic layers are built from tetrachloridozincate anions [ZnCl₄]²⁻ and free water molecules, linked together by O–H···Cl hydrogen bonds and halogen···halogen interactions. In addition, Hirshfeld surfaces and 2D fingerprint plots estimate the weak intermolecular interactions accountable for the generation of crystal packing. The optimized geometry, vibrational frequencies and various thermodynamic parameters of the title compound calculated using density functional theory (DFT) methods are in agreement with the experimental values. The theoretical calculations were performed using the DFT method at WB97XD/Lanl2dz basis set levels and we discussed topological analysis of atoms in molecules (AIM) at the BCP point. A detailed interpretation of the IR and Raman spectra were reported. Additionally, the simulated spectrum satisfactorily coincided with the experimental UV-Visible spectrum. A wide band gap exceeding 4 eV of the synthesized compound was recorded. The photoluminescence (PL) was characterized through two bands successively at 453 and 477 nm. Ultimately, antimicrobial activity and enzymatic inhibition assays of the complex were also investigated through microbial strains, agar diffusion method, minimum inhibitory concentration (MIC) determination, lipase and phospholipase A₂ inhibition. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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20 pages, 5593 KiB

Open AccessArticle

The Electrodegradation Process in PZT Ceramics under Exposure to Cosmic Environmental Conditions

by Iwona Lazar, Christian Rodenbücher, Gustav Bihlmayer, Clive A. Randall, Janusz Koperski, Lutz Nielen, Krystian Roleder and Krzysztof Szot

Molecules 2023, 28(9), 3652; https://doi.org/10.3390/molecules28093652 - 22 Apr 2023

Viewed by 1426

Abstract

Long-time electric field action on perovskite piezoelectric ceramic leads to chemical degradation. A new way to accelerate the degradation is the exposure of the ceramic to DC electric fields under a vacuum. A high-quality commercial piezoelectric material based on PbZr_1−xTi_x [...] Read more.

Long-time electric field action on perovskite piezoelectric ceramic leads to chemical degradation. A new way to accelerate the degradation is the exposure of the ceramic to DC electric fields under a vacuum. A high-quality commercial piezoelectric material based on PbZr_1−xTi_xO₃ is used to study such impacts. To avoid the influence of ferroelectric properties and possible removal of oxygen and lead oxides during the degradation process, the experiments are in the temperature interval of 500 °C > T > T_C. Changes in resistance during the electrodegradation process is an electrically-induced deoxidation, transforming the ceramic into a metallic-like material. This occurs with an extremely low concentration of effused oxygen of 10¹⁶ oxygen atoms per 1 cm³. Due to this concentration not obeying the Mott criterion for an isolator-metal transition, it is stated that the removal of oxygen mostly occurs along the grain boundaries. It agrees with the first-principle calculations regarding dislocations with oxygen vacancies. The decrease in resistivity during electrodegradation follows a power law and is associated with a decrease in the dislocation dimension. The observed reoxidation process is a lifeline for the reconstructing (self-healing) properties of electro-degraded ceramics in harsh cosmic conditions. Based on all of these investigations, a macroscopic and nanoscopic model of the electrodegradation is presented. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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14 pages, 2605 KiB

Open AccessArticle

Crystal Structure of a Chimeric Antigen Receptor (CAR) scFv Domain Rearrangement Forming a VL-VL Dimer

by Jonah Cheung, Shagun Wazir, David R. Bell, James N. Kochenderfer, Wayne A. Hendrickson and Philippe Youkharibache

Crystals 2023, 13(4), 710; https://doi.org/10.3390/cryst13040710 - 21 Apr 2023

Viewed by 2615

Abstract

Chimeric Antigen Receptor T-cell (CAR-T) immunotherapies are dependent upon designed transmembrane proteins to bind target antigens and stimulate an immune response. The success or failure of these CARs is only partially predictable, yet recent work has highlighted the importance of antigen binding scFvs [...] Read more.

Chimeric Antigen Receptor T-cell (CAR-T) immunotherapies are dependent upon designed transmembrane proteins to bind target antigens and stimulate an immune response. The success or failure of these CARs is only partially predictable, yet recent work has highlighted the importance of antigen binding scFvs driving distinct oligomerization states with varied CAR-T efficacy. Here, we sought to determine the extracellular structure of the anti-CD19 CAR 47G4-CD828Z. Unexpectedly, the resolved crystal structure revealed an IgVL homodimer bound along an inverted VL|VL interface. We found that the VL-VH linker, designed to be cleavage resistant, was cleaved, and the VH and CAR hinge domains were absent from the crystal structure lattice. Molecular Dynamics simulations revealed that the inverted VL|VL interface was more stable than the canonical VL|VL configuration. Our work substantiates the need to interrogate the scFv structure and CAR oligomerization state for optimal CAR-T design. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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11 pages, 3519 KiB

Open AccessArticle

Ellipsometry Characterisation for the Cd_1-xZn_xTe_1-ySe_y Semiconductor Used in X-ray and Gamma Radiation Detectors

by Lidia Martínez Herraiz, Jose Luis Plaza Canga-argüelles and Alejandro Francisco Braña de Cal

Crystals 2023, 13(4), 693; https://doi.org/10.3390/cryst13040693 - 18 Apr 2023

Viewed by 964

Abstract

The study of the optical properties of the Cd_1-xZn_xTe_1-ySe_y (CZTS) crystal provides a clear idea about its response to incident X-ray or gamma radiation. This is important for selecting a proper composition of CZTS to achieve [...] Read more.

The study of the optical properties of the Cd_1-xZn_xTe_1-ySe_y (CZTS) crystal provides a clear idea about its response to incident X-ray or gamma radiation. This is important for selecting a proper composition of CZTS to achieve superior quality and high-resolution X-ray and gamma radiation detectors at room temperature and reduce their production cost. This article’s novelty is in lowering the cost of the optical and compositional characterisation of CZTS using the ellipsometry technique. The most significant successes achieved are the composition ellipsometry model determination of CZTS based on the Effective Medium Approximation (EMA) substrate of the binary compound CdTe and ZnSe with an oxide layer of CdTe and the experimental verification that the bandgap moves to lower energies with the addition of Se. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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15 pages, 10695 KiB

Open AccessArticle

Ligand Modulation on the Various Structures of Three Zinc(II)-Based Coordination Polymers for Antibiotics Degradation

by Min Xiong, Ying-Gui Xia, Lu Lu, Jun Wang, A. Mohanty, Yu Wu, Hiroshi Sakiyama, Mohd. Muddassir and Ying Pan

Molecules 2023, 28(7), 2933; https://doi.org/10.3390/molecules28072933 - 24 Mar 2023

Cited by 7 | Viewed by 1507

Abstract

The efficient removal of organic contaminants from wastewater is, nowadays, a prominent area of study due to its biological as well as environmental significance. Antibiotics are now found in wastewater because of their high use, which has become a source of aquatic pollution. [...] Read more.

The efficient removal of organic contaminants from wastewater is, nowadays, a prominent area of study due to its biological as well as environmental significance. Antibiotics are now found in wastewater because of their high use, which has become a source of aquatic pollution. These antibiotics have dangerous implications for people’s health. Hence, effective pharmaceutical removal from wastewater and contaminated water bodies, especially the removal of antibiotics, is of major interest to global research organizations. This is why it is necessary to investigate this class of toxic material in wastewater discharge. We synthesized three different coordination polymers (CPs) in the presence of various assistant carboxylate linkers, namely, [Zn(Hbtc)(dip)]_n (1), [Zn₄(1,2-bdc)₄(dip)₄]_n (2), and [Zn(1,4-bdc)(dip)]_n (3) (3,5-di(1H-imidazol-1-yl)pyridine = dip, 1,3,5-benzenetricarboxylic acid = H₃btc, 1,2-benzenedicarboxylic acid = 1,2-H₂bdc, and 1,4-benzendicarboxylic acid = 1,4-bdc). These CPs were characterized by using different techniques, including single-crystal X-ray diffraction. The structural studies demonstrated that in 2, there are four Zn(II) centers and both centers are in different coordination environments (Zn2 has distorted tetrahedral geometry, whereas Zn1, Zn3, and Zn4 have square pyramidal geometry). Hirshfeld surfaces analysis revealed that different types of intermolecular interactions (C⋯C, H⋯C, H⋯H, O⋯C, N⋯H, and O⋯H) are present in the synthesized CPs. We examined the different antibiotics, such as metronidazole (MDZ), nitrofurazone (NFZ), dimetridazole (DTZ), sulfasalazine(SLA), and oxytetracycline (OXY), degradation behaviors of the synthesized CPs, which showed remarkable degradation efficiency. 1 showed photocatalytic behavior toward the NFZ antibiotic in an aqueous media. This study also showed that these catalysts are stable and reusable under mild conditions. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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27 pages, 5188 KiB

Open AccessArticle

Catalytic, Theoretical, and Biological Investigations of Ternary Metal (II) Complexes Derived from L-Valine-Based Schiff Bases and Heterocyclic Bases

by Gopalakrishnan Sasikumar, Annadurai Subramani, Ramalingam Tamilarasan, Punniyamurthy Rajesh, Ponnusamy Sasikumar, Salim Albukhaty, Mustafa K. A. Mohammed, Subramani Karthikeyan, Zaidon T. Al-aqbi, Faris A. J. Al-Doghachi and Yun Hin Taufiq-Yap

Molecules 2023, 28(7), 2931; https://doi.org/10.3390/molecules28072931 - 24 Mar 2023

Cited by 2 | Viewed by 2217

Abstract

A new series of ternary metal complexes, including Co(II), Ni(II), Cu(II), and Zn(II), were synthesized and characterized by elemental analysis and diverse spectroscopic methods. The complexes were synthesized from respective metal salts with Schiff’s-base-containing amino acids, salicylaldehyde derivatives, and heterocyclic bases. The amino [...] Read more.

A new series of ternary metal complexes, including Co(II), Ni(II), Cu(II), and Zn(II), were synthesized and characterized by elemental analysis and diverse spectroscopic methods. The complexes were synthesized from respective metal salts with Schiff’s-base-containing amino acids, salicylaldehyde derivatives, and heterocyclic bases. The amino acids containing Schiff bases showed promising pharmacological properties upon complexation. Based on satisfactory elemental analyses and various spectroscopic techniques, these complexes revealed a distorted, square pyramidal geometry around metal ions. The molecular structures of the complexes were optimized by DFT calculations. Quantum calculations were performed with the density functional method for which the LACVP++ basis set was used to find the optimized molecular structure of the complexes. The metal complexes were subjected to an electrochemical investigation to determine the redox behavior and oxidation state of the metal ions. Furthermore, all complexes were utilized for catalytic assets of a multi-component Mannich reaction for the preparation of -amino carbonyl derivatives. The synthesized complexes were tested to determine their antibacterial activity against E. coli, K. pneumoniae, and S. aureus bacteria. To evaluate the cytotoxic effects of the Cu(II) complexes, lung cancer (A549), cervical cancer (HeLa), and breast cancer (MCF-7) cells compared to normal cells, cell lines such as human dermal fibroblasts (HDF) were used. Further, the docking study parameters were supported, for which it was observed that the metal complexes could be effective in anticancer applications. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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11 pages, 3117 KiB

Open AccessArticle

Temperature−Dependent Raman Scattering Investigation on vdW Epitaxial PbI₂/CrOCl Heterostructure

by Siwen You, Xiao Guo, Junjie Jiang, Dingbang Yang, Mingjun Li, Fangping Ouyang, Haipeng Xie, Han Huang and Yongli Gao

Crystals 2023, 13(1), 104; https://doi.org/10.3390/cryst13010104 - 06 Jan 2023

Cited by 1 | Viewed by 1890

Abstract

Van der Waals (vdW) epitaxial growth provides an efficient strategy to prepare heterostructures with atomically and electronically sharp interfaces. Herein, PbI₂ was in situ thermally deposited onto exfoliated thin−layered CrOCl nanoflakes in high vacuum to fabricate vdW PbI₂/CrOCl heterostructures. Optical [...] Read more.

Van der Waals (vdW) epitaxial growth provides an efficient strategy to prepare heterostructures with atomically and electronically sharp interfaces. Herein, PbI₂ was in situ thermally deposited onto exfoliated thin−layered CrOCl nanoflakes in high vacuum to fabricate vdW PbI₂/CrOCl heterostructures. Optical microscopy, atomic force microscopy, X−ray diffraction, and temperature−dependent Raman spectroscopy were used to investigate the structural properties and phonon behaviors of the heterostructures. The morphology of PbI₂ films on the CrOCl substrate obviously depended on the substrate temperature, changing from hemispherical granules to 2D nanoflakes with flat top surfaces. In addition, anomalous blueshift of the

A_{g}^{1}

and

A_{u}^{2}

modes as the temperature increased in PbI₂/CrOCl heterostructure was observed for the first time. Our results provide a novel material platform for the vdW heterostructure and a possible method for optimizing heterostructure growth behaviors. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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13 pages, 1688 KiB

Open AccessArticle

One-Dimensional Photonic Crystal with a Defect Layer Utilized as an Optical Filter in Narrow Linewidth LED-Based Sources

by Michal Gryga, Dalibor Ciprian, Lucie Gembalova and Petr Hlubina

Crystals 2023, 13(1), 93; https://doi.org/10.3390/cryst13010093 - 04 Jan 2023

Cited by 9 | Viewed by 2437

Abstract

A one-dimensional photonic crystal (1DPhC) with a defect layer is utilized as an optical filter in a simple realization of narrow linewidth LED-based sources. The 1DPhC comprising TiO

_{2}

and SiO

_{2}

layers is characterized by two narrow defect mode resonances within the [...] Read more.

A one-dimensional photonic crystal (1DPhC) with a defect layer is utilized as an optical filter in a simple realization of narrow linewidth LED-based sources. The 1DPhC comprising TiO

_{2}

and SiO

_{2}

layers is characterized by two narrow defect mode resonances within the 1DPhC band gap, or equivalently, by two peaks in the normal incidence transmittance spectrum at wavelengths of 625.4 nm and 697.7 nm, respectively. By combining the optical filter with LEDs, the optical sources are employed in interferometry experiments, and the defect mode resonances of a Lorentzian profile with linewidths of 1.72 nm and 1.29 nm, respectively, are resolved. In addition, a simple way to tune the resonances by changing the angle of incidence of light on the optical filter is demonstrated. All-dielectric optical filters based on 1DPhCs with a defect layer and combined with LEDs thus represent an effective alternative to standard coherent sources, with advantages including narrow spectral linewidths and variable output power, with an extension to tunable sources. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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13 pages, 2314 KiB

Open AccessArticle

Nitrogen Structure Determination in Treated Fancy Diamonds via EPR Spectroscopy

by Ira Litvak, Avner Cahana, Yaakov Anker, Sharon Ruthstein and Haim Cohen

Crystals 2022, 12(12), 1775; https://doi.org/10.3390/cryst12121775 - 07 Dec 2022

Viewed by 2320

Abstract

Color induction in nitrogen-contaminated diamonds was carried out via various procedures that involve irradiation, thermal treatments (annealing), and more. These treatments affect vacancy defect production and atom orientation centers in the diamond lattice. Natural diamonds underwent color enhancement treatments in order to produce [...] Read more.

Color induction in nitrogen-contaminated diamonds was carried out via various procedures that involve irradiation, thermal treatments (annealing), and more. These treatments affect vacancy defect production and atom orientation centers in the diamond lattice. Natural diamonds underwent color enhancement treatments in order to produce green, blue, and yellow fancy diamonds. The aim of this study was to follow the changes occurring during the treatment, mainly by EPR spectroscopy, which is the main source for the determination of the effect of paramagnetic centers (carbon-centered radicals) on the color centers produced via the treatments, but also via visual assessment, fluorescence, UV-vis, and FTIR spectroscopy. The results indicate that diamonds containing high levels of nitrogen contamination are associated with high carbon-centered radical concentrations. Four paramagnetic center structures (N1, N4, and P2/W21) were generated by the treatment. It is suggested that the N4 structure correlates with the formation of blue color centers, whereas yellow color centers are attributed to the presence of N1 species. While to produce blue and yellow colors, a thermal treatment is needed after irradiation, for treated green diamonds, no thermal treatment is needed (only irradiation). Full article

(This article belongs to the Topic Advanced Structural Crystals)

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19 pages, 2535 KiB

Open AccessArticle

Investigation of Energy Levels of Small Vacancy Clusters in Proton Irradiated Silicon by Laplace Photoinduced Transient Spectroscopy

by Paweł Kamiński, Jarosław Żelazko, Roman Kozłowski, Christian Hindrichsen and Leif Jensen

Crystals 2022, 12(12), 1703; https://doi.org/10.3390/cryst12121703 - 24 Nov 2022

Cited by 2 | Viewed by 1177

Abstract

Laplace photoinduced transient spectroscopy has been applied to determine the electronic properties and concentrations of deep traps in high purity n-type silicon irradiated with high fluences of 23-MeV protons. From the temperature dependence of thermal emission rates of excess charge carriers obtained [...] Read more.

Laplace photoinduced transient spectroscopy has been applied to determine the electronic properties and concentrations of deep traps in high purity n-type silicon irradiated with high fluences of 23-MeV protons. From the temperature dependence of thermal emission rates of excess charge carriers obtained by the analysis of the photocurrent relaxation waveforms measured at temperatures of 30–320 K, eight deep traps with activation energies ranging from 255 to 559 meV have been resolved. The dependence of these trap’s concentrations on the proton fluence are demonstrated for the fluence values ranging from 1 × 10¹⁴ to 5 × 10¹⁵ n_eq/cm². In comparison to the previously reported results of theoretical and experimental studies on the electronic properties of small vacancy clusters in irradiated silicon, we tentatively attribute four detected traps with activation energies of 255, 367, 405, and 512 meV to the energy levels related to the 2−/− charge state changes of divacancy (V₂), trivacancy (V₃), tetravacancy (V₄), and pentavacancy (V₅), respectively. Simultaneously, we propose the attribution of four deep traps with higher activation energies of 415, 456, 526, and 559 meV to the energy levels related to the −/0 charge state changes of these small vacancy clusters, respectively. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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15 pages, 3598 KiB

Open AccessArticle

New Bi-Nuclear Nickel(II) Complex-Based Salen Schiff Base: Synthesis, Crystal Structure, Spectroscopic, Thermal, and Electrical Investigations

by Bouchra Es-Sounni, El Mehdi Haily, Asmae Nakkabi, Mohamed Bakhouch, Linda Bejaoui, Savaş Kaya, Mohamed El Yazidi, Lahcen Bih, Mohamed Saadi, Lahcen El Ammari and Mohammed Fahim

Chemistry 2022, 4(4), 1193-1207; https://doi.org/10.3390/chemistry4040080 - 01 Oct 2022

Viewed by 2129

Abstract

In this study, a new bi-nuclear nickel complex [Ni₂HL₂(EtOH)₂](Cl)(EtOH) of a Schiff base ligand, 2-[3-[2-hydroxybenzylideneamino]propyliminomethyl]phenol, was synthesized and characterized using UV/Vis, IR, HRMS, and TGA/DTA analysis. The molecular structure of the obtained complex was corroborated by the [...] Read more.

In this study, a new bi-nuclear nickel complex [Ni₂HL₂(EtOH)₂](Cl)(EtOH) of a Schiff base ligand, 2-[3-[2-hydroxybenzylideneamino]propyliminomethyl]phenol, was synthesized and characterized using UV/Vis, IR, HRMS, and TGA/DTA analysis. The molecular structure of the obtained complex was corroborated by the single crystal X-ray diffraction technique. It was found in the complex that two molecules of the ligand coordinate with two nickel atoms through azomethine-N and phenoxy-O, resulting in 6-coordinate distorted octahedral geometry, in which two ethanol molecules occupy the axial positions. The dielectric and electrical properties of the obtained samples were studied by impedance spectroscopy at different frequencies (from 1 Hz to 1 MHz) in the temperature range 298–343 K. It is found that the electrical conductivity of the Ni(II) complex is lower than that of the free ligand H₂L, suggesting that the complexation traps the charge carriers contained in the ligand. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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13 pages, 4234 KiB

Open AccessArticle

Eucalyptus globulus Extract-Assisted Fabrication of Copper Oxide/Zinc Oxide Nanocomposite for Photocatalytic Applications

by Muhammad Hafeez, Arooba Ghazal, Jahanzeb Khan, Pervaiz Ahmad, Mayeen Uddin Khandaker, Hamid Osman and Sultan Alamri

Crystals 2022, 12(8), 1153; https://doi.org/10.3390/cryst12081153 - 16 Aug 2022

Cited by 3 | Viewed by 1477

Abstract

In this work, we report the engineering of sub 30 nm nanoparticles of copper oxide (CuO) and Zinc oxide (ZnO) and their nanocomposite, using a green method, to degrade an organic dye (methyl orange) that is responsible for water pollution. The plant extract [...] Read more.

In this work, we report the engineering of sub 30 nm nanoparticles of copper oxide (CuO) and Zinc oxide (ZnO) and their nanocomposite, using a green method, to degrade an organic dye (methyl orange) that is responsible for water pollution. The plant extract of Eucalyptus globulus was used as a capping and stabilizing agent, as it is non-toxic, easy to use, and affordable. The percent purity and composition of the samples were found using Energy Dispersive Spectroscopy (EDS), which confirmed the formation of 75% CuO nanoparticles, 77.81% ZnO nanoparticles, and 77.34% ZnO/CuO nanocomposite in respective samples. Morphological analysis was achieved using Scanning Electron Microscopy (SEM). FTIR investigations revealed that the vibrations of CuO and ZnO nanoparticles and CuO/ZnO nanocomposite were observed at 568 cm⁻¹, 617.9 cm⁻¹, and 475 cm⁻¹, respectively. The bandgap of the synthesized CuO and ZnO nanoparticles, and ZnO/CuO nanocomposite was analyzed using Diffuse Reflectance Spectroscopy (DRS), and found to be 3.36 eV, 1.83 eV, and 1.48 eV, respectively. Best photocatalytic activity confirmed that favorable conditions for the maximum degradation of methyl orange are at pH 12 and 0.02 g of the photocatalyst is required. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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12 pages, 6455 KiB

Open AccessArticle

Molecular Insights into the Effect of Nitrogen Bubbles on the Formation of Tetrahydrofuran Hydrates

by Xin Huang, Zhenchao Li, Le Zhang, Jiayuan He and Hailong Lu

Molecules 2022, 27(15), 4945; https://doi.org/10.3390/molecules27154945 - 03 Aug 2022

Cited by 1 | Viewed by 1651

Abstract

In this work, a molecular dynamics simulation was conducted to study the microscopic mechanism of how nitrogen bubbles affect the formation of THF hydrates at the molecular level. The results obtained reveal that the nitrogen bubble can promote the formation of THF hydrates. [...] Read more.

In this work, a molecular dynamics simulation was conducted to study the microscopic mechanism of how nitrogen bubbles affect the formation of THF hydrates at the molecular level. The results obtained reveal that the nitrogen bubble can promote the formation of THF hydrates. In the system with a nitrogen bubble, more THF-filled cages were generated, and the crystal structure was more orderly. The promotion of nitrogen bubbles on hydrate crystallization comes from the dissolution of nitrogen molecules. Some of dissolved nitrogen molecules can be enclosed in small hydrate cages near the nitrogen bubble, which can serve as stable sites for hydrate crystal growth, resulting in the fact that THF-filled cages connected with N₂-filled cages are much more stable and have a long lifetime. The results in this work can help to understand the promotion effect of micro- and nano-air bubbles on the crystallization of THF hydrates. Full article

(This article belongs to the Topic Advanced Structural Crystals)

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