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18 pages, 4222 KiB

Open AccessArticle

Cooperative Ternary Assemblies Involving Anion–π/π–π/Anion–π Assemblies and Unconventional Cl⋯Cl Interactions in Cu(II) Coordination Compounds: Experimental and Theoretical Studies

by Pinku Sarma, Rosa M. Gomila, Antonio Frontera, Miquel Barcelo-Oliver and Manjit K. Bhattacharyya

Crystals 2023, 13(3), 517; https://doi.org/10.3390/cryst13030517 - 17 Mar 2023

Cited by 4 | Viewed by 1573

Abstract

Two coordination compounds of Cu(II), namely, [Cu (phen)₂Cl](NO₃)·H₂O (compound 1) and [Cu₂(µ-Cl₂)Cl₂(Hdmpz)₄] (compound 2), where phen = 1,10-phenanthroline and Hdmpz = 3,5-dimethylpyrazole, were synthesized at room temperature [...] Read more.

Two coordination compounds of Cu(II), namely, [Cu (phen)₂Cl](NO₃)·H₂O (compound 1) and [Cu₂(µ-Cl₂)Cl₂(Hdmpz)₄] (compound 2), where phen = 1,10-phenanthroline and Hdmpz = 3,5-dimethylpyrazole, were synthesized at room temperature and characterized using elemental analysis, TGA, spectroscopic techniques (FT-IR and electronic) and single-crystal X-ray diffraction studies. The cooperative anion–π/π–π/anion–π assemblies involving the coordinated phen, along with the uncoordinated nitrate moieties, played pivotal roles in the stabilization of the crystal structure of compound 1. Unconventional type I Cl⋯Cl interactions involving the coordinated Cl atoms provided reinforcement to the crystal structure of compound 2. We theoretically explored the supramolecular assemblies observed in the crystal structures of compounds 1 and 2 using DFT calculations, MEP surface analysis and combined NCI plot/QTAIM computational tools. Theoretical analysis revealed that the antiparallel π-stacking interactions in compound 1 and the N–H···Cl H-bonds in compound 2 were the strong structure-guiding non-covalent synthons which stabilized the compounds. In the anion–π/π–π/anion–π assembly observed in compound 1, the anion–π interaction reinforced the π-stacking by reducing the electrostatic repulsion between the metal-coordinated electron-deficient phen rings. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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25 pages, 4811 KiB

Open AccessArticle

Unconventional Dual Donor-Acceptor Topologies of Aromatic Rings in Amine-Based Polymeric Tetrahedral Zn(II) Compounds Involving Unusual Non-Covalent Contacts: Antiproliferative Evaluation and Theoretical Studies

by Pranay Sharma, Rosa M. Gomila, Miquel Barceló-Oliver, Akalesh K. Verma, Diksha Dutta, Antonio Frontera and Manjit K. Bhattacharyya

Crystals 2023, 13(3), 382; https://doi.org/10.3390/cryst13030382 - 23 Feb 2023

Cited by 5 | Viewed by 1672

Abstract

Two Zn(II) coordination polymers, viz., [Zn₂Cl₂(H₂O)₂(µ-4-AmBz)₂]_n (1) and [ZnCl₂(µ-3-AmPy)₂]_n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and [...] Read more.

Two Zn(II) coordination polymers, viz., [Zn₂Cl₂(H₂O)₂(µ-4-AmBz)₂]_n (1) and [ZnCl₂(µ-3-AmPy)₂]_n (2) (4-AmBz = 4-aminobenzoate, 3-AmPy = 3-aminopyridine) have been prepared at room temperature and characterized using elemental analysis, FT-IR, electronic spectroscopy, TGA (thermogravimetric analysis) and single crystal XRD. Crystal structure analyses of the polymers unfold the presence of non-covalent anion–π, π-stacking and unusual NH₂(amino)⋯π interactions which provide rigidity to the crystal structures. Unconventional Type I Cl⋯Cl interactions also play a pivotal role in the stability of compound 1. Molecular electrostatic potential (MEP) surface analysis reveals that the MEP values over the center of the aromatic rings of coordinated 4-AmBz and 3-AmPy moieties are positive on one side and negative on the other side which confirms the dual non-covalent donor-acceptor topologies of the aromatic rings and explains the concurrent formation of unusual non-covalent NH₂···π and anion–π interactions. DFT (density functional theory) calculations, QTAIM (quantum theory of atoms in molecules) and NCI plot (non-covalent index) index analyses reveal that among various non-covalent contacts involved in the crystal packing of the compounds, H-bonds in compound 1 and π-interactions (NH₂···π, π-π, anion–π) in compound 2 are energetically significant. We have explored in vitro cytotoxic potential of the compounds in Dalton’s lymphoma (DL) cancer cells using trypan blue and apoptosis assays. The studies show that compounds 1 and 2 can significantly exhibit cytotoxicity in DL cells with minimum cytotoxicity in healthy PBMC cells. Molecular docking studies reveal that the compounds effectively bind with the antiapoptotic target proteins; thereby establishing a structure activity relationship of the compounds. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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12 pages, 5982 KiB

Open AccessArticle

Chirality as a Feature of the Crystal Structure of Lanthanide Ion Complexes—Some Simple Examples

by Lioubov I. Semenova, Irene Ling and Alexandre N. Sobolev

Crystals 2023, 13(2), 337; https://doi.org/10.3390/cryst13020337 - 16 Feb 2023

Viewed by 1678

Abstract

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)₂Cl₂(OH₂)₂]Cl^.H₂O (bipy = 2,2′-bipyridine), 1; [La₂(phen)₂(O₂CCH₃)₄(NO₃)₂] [...] Read more.

Single-crystal X-ray structure determinations are reported for four lanthanide complexes, [Dy(bipy)₂Cl₂(OH₂)₂]Cl^.H₂O (bipy = 2,2′-bipyridine), 1; [La₂(phen)₂(O₂CCH₃)₄(NO₃)₂] (phen = 1,10-phenanthroline), 2; [Lu(terpy)(O₂CCH₃)₃]^.NaNO₃ (terpy = 2,2′;6′,2″-terpyridine) 3; and [Lu(phen)(O₂CH)₃(OH₂)]^.H₂O, 4. Dispersion interactions within the stacked arrays of coordinated aza-aromatic units found in all four complexes appear to be a significant structural influence in the solid state. For complex 1, there are additional interactions beyond dispersion, which suggests that it may be the means whereby the Δ and Λ forms contribute to the overall chiral nature of the crystal. These weak intermolecular interactions were investigated in detail using the Hirshfeld surface analysis. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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12 pages, 12680 KiB

Open AccessArticle

Matere Bonds in Technetium Compounds: CSD Survey and Theoretical Considerations

by Sergi Burguera, Rosa M. Gomila, Antonio Bauzá and Antonio Frontera

Crystals 2023, 13(2), 187; https://doi.org/10.3390/cryst13020187 - 20 Jan 2023

Cited by 10 | Viewed by 1579

Abstract

Noncovalent interactions involving metals as electron acceptors are continuously under investigation. The term “matere bond” has been proposed to identify noncovalent donor–acceptor interactions where elements of group 7 of the periodic table play the role of the electrophilic site. Most of the works [...] Read more.

Noncovalent interactions involving metals as electron acceptors are continuously under investigation. The term “matere bond” has been proposed to identify noncovalent donor–acceptor interactions where elements of group 7 of the periodic table play the role of the electrophilic site. Most of the works on matere bonds involve rhenium atoms usually in +7 oxidation state. This work emphasizes for the first time their importance in technetium derivatives in several oxidation states (+7, +6, +5, and +3). The Cambridge Structural Database (CSD) in combination with density functional theory (DFT) calculations are used to demonstrate the structure directing role of matere bonds in X-ray structures, even involving anion⋯anion interactions. Further characterization of the matere bonds is provided using Molecular Electrostatic Potential (MEP) surface calculations, the “Quantum Theory of Atoms in Molecules” (QTAIM), and Natural Bond Orbital (NBO) analyses. It should be emphasized that some types of matere bonds reported herein have not been previously described in literature. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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10 pages, 3861 KiB

Open AccessArticle

Solid State Structure and Hydrogen Bonding of Some Cyclic NH Carboximides

by R. Alan Aitken, Alexander J. B. Nelson, Alexandra M. Z. Slawin and Dheirya K. Sonecha

Crystals 2023, 13(1), 150; https://doi.org/10.3390/cryst13010150 - 15 Jan 2023

Viewed by 1515

Abstract

Thirteen new crystal structures of cyclic NH carboximides have been determined and are compared with respect to the mode of intermolecular hydrogen bonding observed in the crystal. The structures include a new cyclobutane-fused succinimide, seven new simple bi- and tricyclic succinimides derived from [...] Read more.

Thirteen new crystal structures of cyclic NH carboximides have been determined and are compared with respect to the mode of intermolecular hydrogen bonding observed in the crystal. The structures include a new cyclobutane-fused succinimide, seven new simple bi- and tricyclic succinimides derived from Diels–Alder reactions of maleimide, three methylated glutarimides, a morpholinedione and adipimide, the first seven-membered ring NH carboximide to be structurally characterised. Overall, seven of the compounds adopt a ribbon structure, five show centrosymmetric dimers, and one has bonding between NH and a remote bridging ether oxygen. Halogen bonding was also detected in one case. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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13 pages, 3541 KiB

Open AccessEditor’s ChoiceArticle

Crystal Engineering of Cation-Radical Salts with Weakly Coordinating Carbadodecaborate Anions

by Emmanuel Adeniyi, Matthias Zeller and Sergiy V. Rosokha

Crystals 2023, 13(1), 99; https://doi.org/10.3390/cryst13010099 - 5 Jan 2023

Cited by 3 | Viewed by 2295

Abstract

An X-ray structural analysis revealed that the salts of N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), N-methylphenothiazine (MPTZ), and octamethylbiphenylene (OMB), with dodecamethyl- or hexabromo-substituted carbadodecaborate anions, comprise layers of the (partially) oxidized organic donors separated by sheets of the bulky counter-ions. The cationic layers comprise either well-separated [...] Read more.

An X-ray structural analysis revealed that the salts of N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), N-methylphenothiazine (MPTZ), and octamethylbiphenylene (OMB), with dodecamethyl- or hexabromo-substituted carbadodecaborate anions, comprise layers of the (partially) oxidized organic donors separated by sheets of the bulky counter-ions. The cationic layers comprise either well-separated TMPD⁺ or MPTZ⁺ cation radicals or π-stacks of partially oxidized OMB moieties consisting of more or less distinct (OMB)₂⁺ units. Quantum mechanical calculations revealed that the formation of essentially isolated cation-radical or π-bonded associations in the salts with these weakly coordinating anions is correlated with the strength of the multicenter π-bonding between cation radicals. This pancake bonding is determined by the balance of the electrostatic repulsion between cationic counterparts and attractive dispersion and weakly covalent interactions. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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23 pages, 8147 KiB

Open AccessArticle

Experimental Study on the Thermal Conductivity of Improved Graphite Composite Insulation Boards

by Genbao Liu, Yutao Guo, Zhiyu Jian, Mojia Huang and Tengfei Zhao

Crystals 2023, 13(1), 102; https://doi.org/10.3390/cryst13010102 - 5 Jan 2023

Cited by 5 | Viewed by 2496

Abstract

The thermal conductivity of thermal insulation materials directly affects the building energy consumption. The types and constituents of thermal insulation materials in thermal insulation boards are the key to determining the insulation performance. By optimizing the material constituents and ratios, this paper proposes [...] Read more.

The thermal conductivity of thermal insulation materials directly affects the building energy consumption. The types and constituents of thermal insulation materials in thermal insulation boards are the key to determining the insulation performance. By optimizing the material constituents and ratios, this paper proposes an improved graphite composite insulation board (GCIB), which has lower thermal conductivity and good fire resistance. Through theoretical derivation, it is found that the limit range of the thermal conductivity of the new GCIB is 0.042–0.064 W/(m · K). Combined with the results of theoretical value analysis, and according to the ratios of material components, the random distribution function of each material component is constructed, and the numerical model of GCIB is established. Through numerical analysis, the range of thermal conductivity of the new composite insulation board is 0.046–0.050 W/(m · K). Finally, we establish an experimental model of the new GCIB. Through the model test of six GCIBs, the thermal conductivity of the new GCIB is obtained as 0.046 W/(m · K), which is in good agreement with the results of theoretical analysis and numerical simulation. Through theoretical analysis, numerical simulation and a sample test, this paper verifies the better thermal insulation performance of the improved GCIB, providing theoretical and numerical simulation methods for the new GCIB, as well as a theoretical reference for the promotion and application of the GCIB. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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10 pages, 7640 KiB

Open AccessEditor’s ChoiceArticle

Interplay of Ionic Species in Salts of Homoleptic Quaternary Phosphonium Cations Bearing Linear Biphenyl Moieties

by Monica Bernard Tan, Alexandre N. Sobolev, Colin L. Raston, Scott J. Dalgarno and Irene Ling

Crystals 2023, 13(1), 59; https://doi.org/10.3390/cryst13010059 - 29 Dec 2022

Viewed by 1929

Abstract

Quaternary phosphonium salts are popular candidates used in many chemical transformations and synthetic chemistry, notably in catalysis. We have examined the single crystals of two bulky phosphonium compounds, tetra([1,1′-biphenyl]-4-yl) phosphonium dicyanamide (C₄₈H₃₆P⁺·N(CN)₂⁻, compound 1 [...] Read more.

Quaternary phosphonium salts are popular candidates used in many chemical transformations and synthetic chemistry, notably in catalysis. We have examined the single crystals of two bulky phosphonium compounds, tetra([1,1′-biphenyl]-4-yl) phosphonium dicyanamide (C₄₈H₃₆P⁺·N(CN)₂⁻, compound 1), and tetra([1,1′-biphenyl]-4-yl) phosphonium bromide hydrate (C₄₈H₃₆P⁺·Br⁻, CH₃CN, H₂O, compound 2), and herein report the structural properties for the compounds with an emphasis on the influence of the ion-ion interaction towards self-assembly; the overall self-assembly for both structures is very similar, with subtle differences in the cell parameters. The symmetrical tetra ([1,1′-biphenyl]-4-yl) phosphonium cations in both compounds self-assembled to form robust stacked columns in the solid-state, with voids occupied by anions or solvent molecules. Quantitative examination of intermolecular interactions using Hirshfeld surface analysis found that classical and non-classical hydrogen bonding appears to be the dominant contributor in stabilizing the self-assembly in both cases. The present work can not only benefit in understanding the mutual interaction between the sterically encumbered tetra ([1,1′-biphenyl]-4-yl) phosphonium cations and between counterions, but also provide insights for the self-assembled arrays in the solid-state. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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18 pages, 4614 KiB

Open AccessArticle

Surfactant Provided Control of Crystallization Polymorphic Outcome and Stabilization of Metastable Polymorphs of 2,6-Dimethoxyphenylboronic Acid

by Aina Semjonova and Agris Bērziņš

Crystals 2022, 12(12), 1738; https://doi.org/10.3390/cryst12121738 - 1 Dec 2022

Cited by 3 | Viewed by 1913

Abstract

2,6-Dimethoxyphenylboronic acid was used as a model substance to investigate the additive crystallization approach for polymorph control in phenylboronic acids. It was crystallized under different conditions by performing evaporation and cooling crystallization from different solvents. Most of the crystallizations from pure solvents produced [...] Read more.

2,6-Dimethoxyphenylboronic acid was used as a model substance to investigate the additive crystallization approach for polymorph control in phenylboronic acids. It was crystallized under different conditions by performing evaporation and cooling crystallization from different solvents. Most of the crystallizations from pure solvents produced the thermodynamically stable Form I, but in evaporation crystallization from alcohols, Form II or even a new polymorph, Form III, could be obtained. Structurally related substances, polymers, and surfactants with diverse intermolecular interaction possibilities were tested as additives. Surfactants were found to facilitate the crystallization of the metastable forms and therefore were investigated more extensively. The surfactants Span 20 and n–octyl-β-D-glucopyranoside provided crystallization of the metastable forms in the evaporation crystallization and notably stabilized Form II. The lattice energy, energy frameworks, Hirshfeld surface analysis, full interaction maps, and morphology prediction were used to identify the structural differences between Forms I and II and rationalize the ability of the additives to provide formation of Form II in the crystallization and to stabilize it. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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14 pages, 3707 KiB

Open AccessArticle

CVD Elaboration of 3C-SiC on AlN/Si Heterostructures: Structural Trends and Evolution during Growth

by Marc Portail, Eric Frayssinet, Adrien Michon, Stéphanie Rennesson, Fabrice Semond, Aimeric Courville, Marcin Zielinski, Remi Comyn, Luan Nguyen, Yvon Cordier and Philippe Vennéguès

Crystals 2022, 12(11), 1605; https://doi.org/10.3390/cryst12111605 - 10 Nov 2022

Cited by 1 | Viewed by 2162

Abstract

(111)-oriented cubic polytypes of silicon carbide (3C-SiC) films were grown by chemical vapor deposition on 2H-AlN(0001)/Si(111) and 2H-AlN(0001)/Si(110) templates. The structural and electrical properties of the films were investigated. For film thicknesses below 300 nm, the 3C-SiC material deposited on 2H-AlN/Si presented a [...] Read more.

(111)-oriented cubic polytypes of silicon carbide (3C-SiC) films were grown by chemical vapor deposition on 2H-AlN(0001)/Si(111) and 2H-AlN(0001)/Si(110) templates. The structural and electrical properties of the films were investigated. For film thicknesses below 300 nm, the 3C-SiC material deposited on 2H-AlN/Si presented a better structural quality than the 3C-SiC films grown directly on Si(111) using the well-established two-step carbonization–epitaxy process. The good lattice match of 3C-SiC with AlN may open a reliable route towards high-quality thin heteroepitaxial 3C-SiC films on a silicon wafer. Nevertheless, the 3C-SiC was featured by the presence of twinned domains and small inclusions of 6H-SiC. The formation of a thin AlSiN film at the AlN/Si interface is also reported. This is the first time such AlSiN layers are described within an AlN/Si heterostructure. Furthermore, noticeable modifications were observed in the AlN film. First, the growth process of SiC on AlN induced a reduction of the dislocation density in the AlN, attesting to the structural healing of AlN with thermal treatment, as already observed for other AlN-based heterostructures with higher-temperature processes. The growth of SiC on AlN also induced a dramatic reduction in the insulating character of the AlN, which could be related to a noticeable cross-doping between the materials. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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24 pages, 10152 KiB

Open AccessArticle

Intermolecular Hydrogen Bonding in Alpha-Hydroxy Carboxylic Acids Crystals: Connectivity, Synthons, Supramolecular Motifs

by Alexander A. Bredikhin, Robert R. Fayzullin, Aidar T. Gubaidullin and Zemfira A. Bredikhina

Crystals 2022, 12(10), 1479; https://doi.org/10.3390/cryst12101479 - 18 Oct 2022

Cited by 4 | Viewed by 1926

Abstract

Synthon theory underlies the analysis and empirical prediction of the crystal structure. Supramolecular synthons (SMSs) formed by intermolecular hydrogen bonds, such as carboxylic

R_{2}^{2}

(8) and

C_{1}^{1}

(4) and alcoholic

C_{1}^{1}

(2) ones, are among the most [...] Read more.

Synthon theory underlies the analysis and empirical prediction of the crystal structure. Supramolecular synthons (SMSs) formed by intermolecular hydrogen bonds, such as carboxylic

R_{2}^{2}

(8) and

C_{1}^{1}

(4) and alcoholic

C_{1}^{1}

(2) ones, are among the most popular. The subject of this publication is the identification of specific synthons in alpha-hydroxycarboxylic acids (AHAs) crystals, in which carboxyl and alcohol fragments are present simultaneously. A series of 11 single-enantiomeric and racemic crystals of substituted lactic acids, the simplest chiral AHA family, were prepared and studied by the single-crystal X-ray diffraction (SC-XRD) method. Advanced analysis of our own and published (Cambridge Structural Database) data on the 33 crystal structures of lactic and achiral AHAs of diverse structures revealed that their supramolecular organization differs significantly from that of simple carboxylic acids. We found that in AHA crystals, hydrogen bonds RC(O)O−H···O(H)−C(R′R′′)C(O)OH (in our notation HB 12) and O=C(OH)C(R′R′′)−O−H···O=C(OH)R′ (HB 23) predominate. The frequency of intermolecular hydrogen bonds is interconnected with the frequency of SMSs. Thus, the synthons mentioned above occur but do not dominate in AHA crystals. Linear synthons

C_{2}^{2}

(6):12/23 and cyclic synthons

R_{2}^{2}

(10):23/23 and

R_{3}^{3}

(11):12/23/23 are most often implemented. An essential role in the choice of cyclic synthons is played by the chiral characteristics of the sample. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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12 pages, 2695 KiB

Open AccessArticle

Eshelby Tensors for Two-Dimensional Decagonal Piezoelectric Quasicrystal Composites

by Guangfang Li and Lianhe Li

Crystals 2022, 12(10), 1456; https://doi.org/10.3390/cryst12101456 - 14 Oct 2022

Cited by 2 | Viewed by 1582

Abstract

The Eshelby tensor for two-dimensional (2D) piezoelectric quasicrystal composites (QCs) is considered. The explicit expressions of Eshelby tensors for 2D piezoelectric QCs are given using the Green’s function method and the interior polarization tensor method, respectively. On this basis, numerical examples of the [...] Read more.

The Eshelby tensor for two-dimensional (2D) piezoelectric quasicrystal composites (QCs) is considered. The explicit expressions of Eshelby tensors for 2D piezoelectric QCs are given using the Green’s function method and the interior polarization tensor method, respectively. On this basis, numerical examples of the Eshelby tensor for 2D piezoelectric QCs with ellipsoidal inclusions are discussed in detail. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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16 pages, 3994 KiB

Open AccessArticle

Synthesis and Crystallographic Characterisation of Pyridyl- and Indoleninyl-Substituted Pyrimido[1,2-b]Indazoles

by Abdul Qaiyum Ramle, Sang Loon Tan and Edward R. T. Tiekink

Crystals 2022, 12(9), 1283; https://doi.org/10.3390/cryst12091283 - 9 Sep 2022

Cited by 2 | Viewed by 1734

Abstract

Pyridyl- and indoleninyl-substituted pyrimido[1,2-b]indazole were synthesised in good to high yields from the condensation reaction of 1,3-dialdehydes with 3-aminoindazoles. The structural features of the compounds were determined by NMR (¹H, ¹³C and ¹⁹F), FT-IR and HR-MS. The [...] Read more.

Pyridyl- and indoleninyl-substituted pyrimido[1,2-b]indazole were synthesised in good to high yields from the condensation reaction of 1,3-dialdehydes with 3-aminoindazoles. The structural features of the compounds were determined by NMR (¹H, ¹³C and ¹⁹F), FT-IR and HR-MS. The spectroscopic assignments were confirmed by X-ray crystallography for two derivatives, i.e., 9-Bromo-3-(pyridin-4-yl)pyrimido[1,2-b]indazole (1b) and 10-Methoxy-3-(pyridin-4-yl)pyrimido[1,2-b]indazole (1c), which further provides support for significant delocalisation of π-electron density over the entire fused ring system. The molecular packing was assessed by conventional methods together with Hirshfeld surface analyses. In 1b, the molecular packing features pyrimidyl-N–H···N(pyrimidyl), π(pyrazolyl)···π(pyrimidyl) and Br···N interactions within a two-dimensional array. In 1c, pyrimidyl-C–H···N(pyrazolyl) and pyridyl-C–H···O(methoxy) interactions feature within a three-dimensional architecture. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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19 pages, 3584 KiB

Open AccessArticle

Synthesis, Crystal Structure, DFT Studies and Optical/Electrochemical Properties of Two Novel Heteroleptic Copper(I) Complexes and Application in DSSC

by Samuel Soto-Acosta, José J. Campos-Gaxiola, Edgar A. Reynoso-Soto, Adriana Cruz-Enríquez, Jesús Baldenebro-López, Herbert Höpfl, Juventino J. García, Marcos Flores-Álamo, Valentín Miranda-Soto and Daniel Glossman-Mitnik

Crystals 2022, 12(9), 1240; https://doi.org/10.3390/cryst12091240 - 1 Sep 2022

Cited by 4 | Viewed by 2693

Abstract

New copper(I) compounds of compositions [Cu(HL)(PPh₃)₂]·H₂O (1) and [Cu(HL)POP]·CH₂Cl₂ (2), where HL = monoanion of pyridine-2,5-dicarboxylic acid, PPh₃ = triphenylphosphine and POP = bis [2-(diphenylphosphine)phenyl]ether), are documented. The complexes [...] Read more.

New copper(I) compounds of compositions [Cu(HL)(PPh₃)₂]·H₂O (1) and [Cu(HL)POP]·CH₂Cl₂ (2), where HL = monoanion of pyridine-2,5-dicarboxylic acid, PPh₃ = triphenylphosphine and POP = bis [2-(diphenylphosphine)phenyl]ether), are documented. The complexes were characterized by elemental analysis, spectroscopic techniques (IR, ¹H/³¹P RMN and UV–VIS), cyclic voltammetry, and thermogravimetric analysis. Single-crystals for 1 and 2 enabled X-ray diffraction analysis, revealing distorted tetrahedral geometries for Cu(I) centers embedded in NOP₂ environments. The crystal structures are stabilized by O−H∙∙∙O, C−H∙∙∙O, C−H∙∙∙π and π∙∙∙π interactions that were analyzed by inspection of the Hirshfeld surfaces and fingerprint plots. Compounds 1 and 2 show interesting optical/electrochemical properties, which were studied experimentally in solution by UV–Vis spectroscopy and cyclic voltammetry, as well as theoretically using Time-Dependent Density Functional Theory (TD-DFT). Additionally, in combination with the ruthenium complex N719, their efficiency as co-sensitizers in dye-sensitized solar cells (DSSCs) was assessed, showing good activity. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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10 pages, 30780 KiB

Open AccessArticle

Temperature Effect on Short—Term Strength of Lithium Hydride with Tensile and Three—Point Bend Specimens

by Lei Peng, Dexiang Zhou, Wangzi Zhang, Yifan Shi and Yao Xie

Crystals 2022, 12(6), 840; https://doi.org/10.3390/cryst12060840 - 15 Jun 2022

Cited by 4 | Viewed by 1691

Abstract

Strength is one important mechanical property of lithium hydride (LiH) for application as a neutron moderator and absorbent at elevated temperatures. Using the digital image correlation (DIC) method for deformation measurement, the short—term strength of LiH was investigated with both tensile and three—point [...] Read more.

Strength is one important mechanical property of lithium hydride (LiH) for application as a neutron moderator and absorbent at elevated temperatures. Using the digital image correlation (DIC) method for deformation measurement, the short—term strength of LiH was investigated with both tensile and three—point bend (3PB) specimens in the range of room temperature (RT) to 600 °C. The results show that the temperature dependence of the strength from tensile and 3PB tests shows similarity. As the temperature increases, the strength changes slightly, then rises to the maximum and finally decreases due to the softening effect. The fracture surfaces of specimens show the main characteristics of trans—granular fracture at different temperatures, except for 600 °C. With increasing temperature, the fracture surfaces become rough and numerous tortuous micro—cracks are found. Especially for 3PB specimens, there are dimple—like structures with distorted grains and obvious intergranular cleavage fracture. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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12 pages, 2386 KiB

Open AccessFeature PaperArticle

NAi/Li Antisite Defects in the Li_1.2Ni_0.2Mn_0.6O₂ Li-Rich Layered Oxide: A DFT Study

by Mariarosaria Tuccillo, Angelo Costantini, Arcangelo Celeste, Ana Belén Muñoz García, Michele Pavone, Annalisa Paolone, Oriele Palumbo and Sergio Brutti

Crystals 2022, 12(5), 723; https://doi.org/10.3390/cryst12050723 - 19 May 2022

Cited by 3 | Viewed by 2988

Abstract

Li-rich layered oxide (LRLO) materials are promising positive-electrode materials for Li-ion batteries. Antisite defects, especially nickel and lithium ions, occur spontaneously in many LRLOs, but their impact on the functional properties in batteries is controversial. Here, we illustrate the analysis of the formation [...] Read more.

Li-rich layered oxide (LRLO) materials are promising positive-electrode materials for Li-ion batteries. Antisite defects, especially nickel and lithium ions, occur spontaneously in many LRLOs, but their impact on the functional properties in batteries is controversial. Here, we illustrate the analysis of the formation of Li/Ni antisite defects in the layered lattice of the Co-free LRLO Li_1.2Mn_0.6Ni_0.2O₂ compound through a combination of density functional theory calculations performed on fully disordered supercells and a thermodynamic model. Our goal was to evaluate the concentration of antisite defects in the trigonal lattice as a function of temperature and shed light on the native disorder in LRLO and how synthesis protocols can promote the antisite defect formation. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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25 pages, 6095 KiB

Open AccessArticle

Croconic Acid Doped Triglycine Sulfate: Crystal Structure, UV-Vis, FTIR, Raman, Photoluminescence Spectroscopy, and Dielectric Properties

by Elena Balashova, Aleksandr A. Levin, Valery Davydov, Alexander Smirnov, Anatoly Starukhin, Sergey Pavlov, Boris Krichevtsov, Andrey Zolotarev, Hongjun Zhang, Fangzhe Li and Hua Ke

Crystals 2022, 12(5), 679; https://doi.org/10.3390/cryst12050679 - 9 May 2022

Cited by 4 | Viewed by 2336

Abstract

Triglycine sulfate (TGS) single crystals doped with croconic acid (CA) were grown by evaporation from aqueous solutions. X-ray diffraction analysis shows a slight reduction in unit cell volume in TGS:CA compared to pure TGS crystals. The polarized Raman and near-infrared absorption spectra show [...] Read more.

Triglycine sulfate (TGS) single crystals doped with croconic acid (CA) were grown by evaporation from aqueous solutions. X-ray diffraction analysis shows a slight reduction in unit cell volume in TGS:CA compared to pure TGS crystals. The polarized Raman and near-infrared absorption spectra show that the positions of most lines resulting from inter- and intramolecular vibrations are in good agreement with those in spectra of undoped TGS crystals. The inclusion of CA in TGS is confirmed by the presence of bands characteristic of CA in the infrared-Fourier transform spectra. The ultraviolet-visible absorption spectra of TGS:CA are characterized by the presence of additional absorption bands (compared to the spectra of pure TGS) located in the transparent region of pure TGS. In the photon energy region 1.6–3.6 eV, a strong “green” luminescence band is present in TGS:CA upon excitation at λ = 325 nm. The position of the emission band depends on the wavelength of the exciting light. Doping of TGS with CA causes pinning of domain walls, which is accompanied by a decrease in amplitude and frequency dispersion of the dielectric anomaly at the phase transition, a decrease in the switchable polarization and an increase in the coercive field of hysteresis loops. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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10 pages, 3935 KiB

Open AccessArticle

Study on the Grain Rotation of High-Purity Tantalum during Compression Deformation

by Qianqian Zhu, Yahui Liu, Kexing Song, Yanjun Zhou, Xiaokang Yang, Shifeng Liu and Lingfei Cao

Crystals 2022, 12(5), 676; https://doi.org/10.3390/cryst12050676 - 9 May 2022

Cited by 2 | Viewed by 1533

Abstract

A compression experiment with electron backscatter diffraction (EBSD) measurements was designed to characterize the effect of the microtexture on the grain rotation process. The rotation degrees of more than 180 grains before and after the compression were calculated. Results showed that grains with [...] Read more.

A compression experiment with electron backscatter diffraction (EBSD) measurements was designed to characterize the effect of the microtexture on the grain rotation process. The rotation degrees of more than 180 grains before and after the compression were calculated. Results showed that grains with different crystallographic orientations experienced various rotation degrees. Furthermore, grains in certain microtexture regions also had varying degrees of rotation. The compression led to the lattice rotation and change in orientation of individual grains, but the relative misorientation between grains has not changed much in the microtexture region. The microtexture region, as a whole, participated in the compression process. The similar slipping behavior of the grains in the region promoted the slip transmission between the neighboring grains. Thus, the amount of piled-up dislocations at grain boundaries inside the microtexture region are less than that at grain boundaries outside the microtexture region, leading to a small stored energy density for grain boundaries inside the microtexture region. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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7 pages, 2519 KiB

Open AccessEditor’s ChoiceArticle

Growth and Passive Q-Switching Application of Cr:TiTe₃O₈ Crystal

by Chengcheng Li, Zeliang Gao, Zhongjun Zhai, Shuai Ye and Youxuan Sun

Crystals 2022, 12(4), 558; https://doi.org/10.3390/cryst12040558 - 15 Apr 2022

Cited by 1 | Viewed by 2130

Abstract

A Cr⁴⁺-doped TiTe₃O₈ crystal with dimensions up to 21 mm × 21 mm × 11 mm was grown successfully by the top-seeded solution growth method. A high-resolution X-ray diffraction experiment showed that the full width at half-maximum of [...] Read more.

A Cr⁴⁺-doped TiTe₃O₈ crystal with dimensions up to 21 mm × 21 mm × 11 mm was grown successfully by the top-seeded solution growth method. A high-resolution X-ray diffraction experiment showed that the full width at half-maximum of the rocking curve was 41.90″. Energy-dispersive spectrometry (EDS) and X-ray fluorescence spectroscopy (XRF) proved that Cr⁴⁺ ions have been doped into the TiTe₃O₈ crystal with molar percentage of 4.9%. The Cr:TiTe₃O₈ crystal exhibited an absorption range from 995 to 1565 nm, which is suitable for passive Q switch at 1064 nm. Then, a passive Q-switching solid-state laser operating at 1064 nm was realized using a Cr:TiTe₃O₈ crystal as the saturable absorber. The maximum laser pulse energy is calculated to be 0.7 μJ, and the maximum peak power reaches 0.7 W. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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19 pages, 3587 KiB

Open AccessArticle

New Co-Crystals/Salts of Gallic Acid and Substituted Pyridines: An Effect of Ortho-Substituents on the Formation of an Acid–Pyridine Heterosynthon

by Gleb L. Denisov and Yulia V. Nelyubina

Crystals 2022, 12(4), 497; https://doi.org/10.3390/cryst12040497 - 3 Apr 2022

Cited by 6 | Viewed by 3194

Abstract

Co-crystallization of gallic acid with pyridines and their polyaromatic analogue, quinoline, ortho-substituted by various proton-donating groups able to form hydrogen bonds, produced the only reported co-crystal of gallic acid with an ortho-substituted pyridine, 2-hydroxypyridine, as its preferred pyridone-2 tautomer, and four new [...] Read more.

Co-crystallization of gallic acid with pyridines and their polyaromatic analogue, quinoline, ortho-substituted by various proton-donating groups able to form hydrogen bonds, produced the only reported co-crystal of gallic acid with an ortho-substituted pyridine, 2-hydroxypyridine, as its preferred pyridone-2 tautomer, and four new crystalline products of gallic acid. These co-crystals, or gallate salts depending on the choice of the pyridine-containing compound, as predicted by the pKa rule, were identified by X-ray diffraction to feature the popular acid–pyridine heterosynthon found in most of the two-component systems of gallic acid that lack ortho-substituents in the pyridine-containing compound. This single-point heterosynthon is, however, modified by one or two proton-donating ortho-substituents, which sometimes may transform into the proton acceptors in an adopted tautomer or zwitterion, to produce its two- or other multi-point variants, including a very rare four-point heterosynthon. The hydrogen bonds they form with the gallic acid species in the appropriate co-crystals/salts strongly favors the formation of the acid–pyridine heterosynthon over the acid–acid homosynthon. In the competitive conditions of multi-component systems, such a modification might be used to reduce supramolecular-synthon-based polymorphism to produce new pharmaceuticals and other crystalline materials with designed properties. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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21 pages, 9640 KiB

Open AccessArticle

Synthesis of New Homopiperazine-1.4-Diium Tetrachloridromercurate (II) Monohydrate (C₅H₁₄N₂)[HgCl₄]·H₂O, Crystal Structure, Hirshfeld Surface, Spectroscopy, Thermal Analysis, Antioxidant Activity, Electric and Dielectric Behavior

by Chaima Ayari, Abdullah A. Alotaibi, Mohammed A. Baashen, Khalid M. Alotaibi, Khadijah H. Alharbi, Abdelhak Othmani, Wataru Fujita, Cherif Ben Nasr and Mohamed Habib Mrad

Crystals 2022, 12(4), 486; https://doi.org/10.3390/cryst12040486 - 31 Mar 2022

Cited by 9 | Viewed by 2222

Abstract

Using acid–base assays and simple slow evaporation method at ambient temperature, we were successful in producing a novel salt with the chemical formula (C₅H₁₄N₂)[HgCl₄]·H₂O. According to single-crystal X-ray diffraction data, the crystal packing [...] Read more.

Using acid–base assays and simple slow evaporation method at ambient temperature, we were successful in producing a novel salt with the chemical formula (C₅H₁₄N₂)[HgCl₄]·H₂O. According to single-crystal X-ray diffraction data, the crystal packing was regulated by H-bonds and by Coulomb interactions (also called electrostatic interactions) between distinct entities, which formed a 3D network. The 2D fingerprint plots and the Hirshfeld surface were utilized to examine the effect of intermolecular interactions. FTIR spectroscopy, PL spectroscopy, thermal analysis, and electrical conductivity experiments were also carried out, and the antioxidant activity was tested. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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19 pages, 6508 KiB

Open AccessFeature PaperArticle

Between Harmonic Crystal and Glass: Solids with Dimpled Potential-Energy Surfaces Having Multiple Local Energy Minima

by Nikolai A. Zarkevich and Duane D. Johnson

Crystals 2022, 12(1), 84; https://doi.org/10.3390/cryst12010084 - 8 Jan 2022

Cited by 3 | Viewed by 2671

Abstract

Solids with dimpled potential-energy surfaces are ubiquitous in nature and, typically, exhibit structural (elastic or phonon) instabilities. Dimpled potentials are not harmonic; thus, the conventional quasiharmonic approximation at finite temperatures fails to describe anharmonic vibrations in such solids. At sufficiently high temperatures, their [...] Read more.

Solids with dimpled potential-energy surfaces are ubiquitous in nature and, typically, exhibit structural (elastic or phonon) instabilities. Dimpled potentials are not harmonic; thus, the conventional quasiharmonic approximation at finite temperatures fails to describe anharmonic vibrations in such solids. At sufficiently high temperatures, their crystal structure is stabilized by entropy; in this phase, a diffraction pattern of a periodic crystal is combined with vibrational properties of a phonon glass. As temperature is lowered, the solid undergoes a symmetry-breaking transition and transforms into a lower-symmetry phase with lower lattice entropy. Here, we identify specific features in the potential-energy surface that lead to such polymorphic behavior; we establish reliable estimates for the relative energies and temperatures associated with the anharmonic vibrations and the solid–solid symmetry-breaking phase transitions. We show that computational phonon methods can be applied to address anharmonic vibrations in a polymorphic solid at fixed temperature. To illustrate the ubiquity of this class of materials, we present a range of examples (elemental metals, a shape-memory alloy, and a layered charge-density-wave system); we show that our theoretical predictions compare well with known experimental data. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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Review

Jump to: Research

13 pages, 1986 KiB

Open AccessReview

Heterotridentate Organomonophosphines in Pt(κ³–X¹P¹X²)(Y) (X^1,2 = N^1,2 or S^1,2), Pt(κ³–P¹N¹X¹)(Y) (X¹ = O, C, S or Se) Pt(κ³–P¹S¹Cl¹)(Cl) and Pt(κ³–P¹Si¹N¹)(OL)—Structural Aspects

by Milan Melník and Peter Mikuš

Crystals 2022, 12(12), 1772; https://doi.org/10.3390/cryst12121772 - 6 Dec 2022

Cited by 2 | Viewed by 1237

Abstract

This review covers twenty four Pt(II) complexes of the inner coordination sphere Pt(κ³–P¹ N¹N²)(Y), (Y = Cl, CL); Pt(κ³–P¹N¹X¹)(Y), (X¹ = O¹ and Y = P [...] Read more.

This review covers twenty four Pt(II) complexes of the inner coordination sphere Pt(κ³–P¹ N¹N²)(Y), (Y = Cl, CL); Pt(κ³–P¹N¹X¹)(Y), (X¹ = O¹ and Y = P²L, Cl, I); (X¹ = C¹ and Y = NL, Cl); (X¹ = S¹ and Y = Cl, I); (X¹ = Se¹ and Y = Cl); Pt(κ³–N¹P¹N²)(Cl), Pt(κ³–S¹P¹S²)(Cl), Pt(κ³–P¹S¹Cl¹)(Cl) and Pt(κ³–P¹Si¹N¹)(OL). These complexes are crystallized in three crystal classes: monoclinic (16 examples), triclinic (5 examples), and orthorhombic (3 examples). Each κ³–ligand creates two metallocyclic rings with various combinations of the respective metallocyclic rings. If the common central ligating atom is N¹, the 5 + 5 membered, 5 + 5, 5 + 6, 6 + 5, and 6 + 6; if the common central ligating atom is P¹: 5 + 5, and 6 + 6; if the common central ligating atom is S¹ or Si¹, 5 + 6-membered. The structural parameters (Pt-L, L-Pt-L) are analysed and discussed with an attention to the distortion of a square-planar geometry about the Pt(II) atoms as well as trans-influence. The sums of the Pt-L (x = 4) bond distances the growing with the covalent radius of the Y atoms. Noticeably, the distortion of the square-planar geometry is growing with the decreasing size of the inner coordination sphere about the Pt(II) atom. There is a relation between the degree of distortion (Ʈ₄) and the numbers of the metallocycles rings. The distortion diminishing is in the order of: 0.058 (5 + 5) > 0.037 (6 + 5) > 0.023 (5 + 6) > 0.022 (6 + 6) membered. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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