Feature Papers in Organic Crystalline Materials

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Organic Crystalline Materials".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 25778

Special Issue Editors

School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
Interests: supramolecular chemistry; crystal engineering; chemical nanoscience; molecular organisation from solid-state and solution-based self-assembly of nanoscale molecular architectures to success in surface molecular organisation
Department of Chemistry, Sayyed Jamaleddin Asadabadi University, Asadabad 6541861841, Iran
Interests: coordination polymer; metal-organic framework; nanocatalyst; Lanthanide-doped semiconductor and advanced materials for wastewater remediation
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Special Issue Information

Dear Colleagues,

The Section Organic Crystalline Materials of Crystals provides a forum to report advances in our understanding of all topics concerning crystalline materials containing organic molecules. Studies of organic crystalline structure include supramolecular interactions between molecules such as hydrogen bonding, halogen bonding, and stacking interactions; functional materials prepared using organic molecules, including assemblies of dyes or radicals; and porous organic structures such as metal–organic frameworks (MOFs) or hydrogen-bonded organic frameworks (HOFs). Analysis of packing arrangements of organic molecules and how these affect polymorphs and functional properties. Organometallic molecules, in addition to purely organic systems, are also deemed suitable for submissions.

The aim of this Special Issue on “Reviewing featured topics in Organic Crystalline Materials” is to review the knowledge on featured topics in the organic crystals field. To achieve this, the Special Issue edited by the Editor-in-Chief and all academic editors is inviting prominent scientists in the field to submit reviews focused on organic crystalline structures including those that employ supramolecular interactions between molecules, organic crystal polymorphs, functional materials developed from organic molecules, and porous organic structures (MOFs and HOFs). The coverage of topics of this Special Issue is as broad as that of the Section Organic Crystalline Materials, as described above.

We therefore very much look forward to your valued contributions to make this Special Issue a reference resource of essential knowledge for future researchers in the Organic Crystalline Materials field.

Prof. Dr. Neil Champness
Prof. Dr. Younes Hanifehpour
Guest Editors

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Keywords

  • organic crystalline materials
  • supramolecular interactions
  • organic crystal polymorphs
  • functional organic materials
  • porous organic structures
  • metal–organic frameworks (MOFs)
  • hydrogen-bonded organic frameworks (HOFs)

Published Papers (13 papers)

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Research

12 pages, 2513 KiB  
Article
Crystal Structure of New 1-Phenyl-Substituted Tribenzsilatranes
by Vitalijs Romanovs, Sergey Belyakov, Evgeniya Doronina, Valery Sidorkin, Thierry Roisnel and Viatcheslav Jouikov
Crystals 2023, 13(5), 772; https://doi.org/10.3390/cryst13050772 - 06 May 2023
Viewed by 793
Abstract
The family of practically requested “common” silatrane derivatives of triethanolamine X-Si(OCH2CH2)3N, 1, was enlarged with the first representatives of 3,4,6,7,10,11-tribenzo-2,8,9trioxa-5-aza-1-silatricyclo(3.3.3.0^1,5^)undecanes X-Si(O-para-R-C6H3)3N, tribenzsilatranes 2 (R = H (a [...] Read more.
The family of practically requested “common” silatrane derivatives of triethanolamine X-Si(OCH2CH2)3N, 1, was enlarged with the first representatives of 3,4,6,7,10,11-tribenzo-2,8,9trioxa-5-aza-1-silatricyclo(3.3.3.0^1,5^)undecanes X-Si(O-para-R-C6H3)3N, tribenzsilatranes 2 (R = H (a), Me (b), F (c)), carrying the substituent R in the side aromatic rings. These compounds were prepared via the transesterification of phenyl trimethoxysilane with the corresponding triphenol amines and studied using XRD and DFT calculations. These derivatives of 1-X-(4-R-2,2′,2′′-nitrilotriphenoxy)silane are expected to have, as their parent “common” silatranes 1, diverse biological and pharma activities. A common characteristic feature of the molecular structures of both 1 and 2 is the presence of an intramolecular dative bond N→Si whose existence is evidenced by geometric and quantum topological (AIM) criteria. In the crystals, the length of this bond (dSiN) is noticeably longer in tribenzsilatranes than in 1. The results of DFT B3PW91/6-311++G(d,p) calculations suggest the reason for this to be the more rigid nature of the potential functions of the N→Si bond deformation in 2 compared to 1. The relative degree of “softness”/”hardness” of the potential functions can be assessed from the difference in the calculated values of dSiN in isolated molecules 1 and 2a–c and in their crystals. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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16 pages, 3379 KiB  
Article
Computational Study of Benzothiazole Derivatives for Conformational, Thermodynamic and Spectroscopic Features and Their Potential to Act as Antibacterials
by Adeel Mubarik, Sajid Mahmood, Nasir Rasool, Muhammad Ali Hashmi, Muhammad Ammar, Sadaf Mutahir, Kulsoom Ghulam Ali, Muhammad Bilal, Muhammad Nadeem Akhtar and Ghulam Abbas Ashraf
Crystals 2022, 12(7), 912; https://doi.org/10.3390/cryst12070912 - 27 Jun 2022
Cited by 6 | Viewed by 1843
Abstract
Benzothiazole analogs are very interesting due to their potential activity against several infections. In this research, five benzothiazole derivatives were studied using density functional theory calculations. The optimized geometry, geometrical parameters and vibrational spectra were analyzed. The charge distribution diagrams, such as FMO [...] Read more.
Benzothiazole analogs are very interesting due to their potential activity against several infections. In this research, five benzothiazole derivatives were studied using density functional theory calculations. The optimized geometry, geometrical parameters and vibrational spectra were analyzed. The charge distribution diagrams, such as FMO (HOMO-LUMO), energies of HOMO-LUMO, polarizability, hyperpolarizability, MESP and density of states, were calculated. The computed energies of HOMO and LUMO showed that the transfer of charge occurred within the compound. The effect of the change of substituents on the ring on the value of the HOMO-LUMO energy gap was also observed. It was observed that, in this series, compound 4 with CF3 substituent had the lowest energy gap of HOMO-LUMO, and compound 5 with no substituent had highest HOMO-LUMO energy gap. From the energies of HOMO and LUMO, the reactivity descriptors, such as electron affinity (A), ionization potential (I), chemical softness (σ), chemical hardness (ƞ), electronic chemical potential (μ), electrophilicity index (ω), were calculated. In addition, the 13C and 1H NMR chemical shifts of the molecules were calculated using the gauge-independent atomic orbit (GIAO) method; the shifts were in good agreement with the experimental values. The anti-bacterial potential of compounds 1 to 5 was tested by molecular docking studies toward target proteins 2KAU and 7EL1 from Klebsiella aerogenes and Staphylococcus aureus. Compounds 3 and 1 showed high affinity toward 2KAU and 7EL1, respectively. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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22 pages, 10147 KiB  
Article
Crystalline Derivatives of Dipyrazolo-1,5-diazocine and Dipyrazolopyrimidine: A Case of Unexpected Synthesis and Isostructural Polymorphism
by Fernando Cuenú-Cabezas, Rodrigo Abonia and Jovanny A. Gómez Castaño
Crystals 2022, 12(5), 714; https://doi.org/10.3390/cryst12050714 - 17 May 2022
Cited by 1 | Viewed by 1356
Abstract
Pyrazole-phenylmethanimines (Shiff bases), Py–N=CH–Ph, form molecular crystals whose supramolecular and self-assembly properties can be tuned according to the substitution made on the aromatic and pyrazole rings. In pursuit of the first pyrazole-pyridinemethanimine member, Py–N=CH–Pyr, by following the well-known synthetic scheme for these Shiff [...] Read more.
Pyrazole-phenylmethanimines (Shiff bases), Py–N=CH–Ph, form molecular crystals whose supramolecular and self-assembly properties can be tuned according to the substitution made on the aromatic and pyrazole rings. In pursuit of the first pyrazole-pyridinemethanimine member, Py–N=CH–Pyr, by following the well-known synthetic scheme for these Shiff bases, two hitherto unknown crystalline derivatives of dipyrazolo-1,5-diazocine and dipyrazolopyrimidine were obtained instead, this depending on the use or not of acetic acid as the catalyst. 1,5-diazocine crystallizes in a single P-1 triclinic packing system (Z = 2, Z′ = 1), while dipyrazolopyrimidine exhibits isostructural dimorphic behavior by adopting two (pale pink and yellow) alike P21/c monoclinic systems (both Z = 4, Z′ = 1) as a function of the solvent used. Crystal structures were resolved by means of X-ray diffraction technique and their intramolecular, intermolecular, and supramolecular assemblies analyzed with the assistance of decorated Hirshfeld surfaces and the topology study of electron density using the quantum-theory of atoms in molecules (QTAIM). Although both dipyrazolopyrimidine polymorphs are stabilized by the same type of noncovalent motifs, the pale pink crystal has a slightly more compact structure, with more efficient inter- and intramolecular interactions. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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15 pages, 7274 KiB  
Article
Improving Optoelectrical Properties of PEDOT: PSS by Organic Additive and Acid Treatment
by Shui-Yang Lien, Po-Chen Lin, Wen-Ray Chen, Chuan-Hsi Liu, Po-Wen Sze, Na-Fu Wang and Chien-Jung Huang
Crystals 2022, 12(4), 537; https://doi.org/10.3390/cryst12040537 - 11 Apr 2022
Cited by 3 | Viewed by 1755
Abstract
This article demonstrates the change of structural and optical properties of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) by organic additive and acid treatment. The addition of sorbitol and maltitol can disperse the micelles of PEDOT: PSS. The mechanism of the bond-breaking reaction [...] Read more.
This article demonstrates the change of structural and optical properties of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) by organic additive and acid treatment. The addition of sorbitol and maltitol can disperse the micelles of PEDOT: PSS. The mechanism of the bond-breaking reaction was investigated and a model for the bond-breaking reaction is also proposed. Furthermore, multiple formic acid treatments were found to reduce the PSS content of PEDOT: PSS, resulting in an enhancement in conductivity (4.2 × 104 S/m). Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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13 pages, 3553 KiB  
Article
Effect of Non-Covalent Interactions on the 2,4- and 3,5-Dinitrobenzoate Eu-Cd Complex Structures
by Maxim A. Shmelev, Aleksandr S. Chistyakov, Galina A. Razgonyaeva, Vladimir V. Kovalev, Julia K. Voronina, Fedor M. Dolgushin, Natalia V. Gogoleva, Mikhail A. Kiskin, Alexey A. Sidorov and Igor L. Eremenko
Crystals 2022, 12(4), 508; https://doi.org/10.3390/cryst12040508 - 06 Apr 2022
Cited by 6 | Viewed by 1806
Abstract
Heterometallic {Eu2Cd2} complexes [Eu2(NO3)2Cd2(Phen)2(2,4-Nbz)8]n·2nMeCN (I) and [Eu2(MeCN)2Cd2(Phen)2(3,5-Nbz)10] (II) with the 2,4-dinitrobenzoate (2,4-Nbz) and [...] Read more.
Heterometallic {Eu2Cd2} complexes [Eu2(NO3)2Cd2(Phen)2(2,4-Nbz)8]n·2nMeCN (I) and [Eu2(MeCN)2Cd2(Phen)2(3,5-Nbz)10] (II) with the 2,4-dinitrobenzoate (2,4-Nbz) and 3,5-dinitrobenzoate (3,5-Nbz) anions and 1,10-phenanthroline were synthesized. The compounds obtained were characterized by X-ray single-crystal analysis, powder X-ray diffraction analysis, IR spectroscopy, and elemental analysis. Moreover, the thermal stability of the complexes was also studied. Analysis of the crystal packing showed that where 1,10-phenanthroline is combined with various isomers of dinitrobenzoate anions, different arrangements of non-covalent interactions are observed in the complex structures. In the case of the compound with the 2,4-dinitrobenzoate anion, these interactions lead to a significant distortion of the metal core geometry and formation of a polymeric structure, while the complex with the 3,5-dinitrobenzoate anion has a structure that is typical of similar systems. The absence of europium metal-centered luminescence at 270 nm wavelength was shown. For all the reported compounds, a thermal stability study was carried out that showed that the compounds decomposed with a significant thermal effect. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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14 pages, 3235 KiB  
Article
Anharmonic Motion in the Crystal Structure of 2-Mercaptopyridone
by Martin Lutz, Tom J. Smak and Arnaud T. Sanderse
Crystals 2022, 12(3), 338; https://doi.org/10.3390/cryst12030338 - 28 Feb 2022
Cited by 1 | Viewed by 1874
Abstract
With the present study, we revise earlier results about the title compound 2-mercaptopyridone in which the deformation density was determined from an X–N study in 1982 (X-ray, neutron diffraction). In the current X–X study (X-ray, X-ray), anharmonic motion parameters for the atoms were [...] Read more.
With the present study, we revise earlier results about the title compound 2-mercaptopyridone in which the deformation density was determined from an X–N study in 1982 (X-ray, neutron diffraction). In the current X–X study (X-ray, X-ray), anharmonic motion parameters for the atoms were included and it resulted in a very clean deformation density map without the unexplainable features of the literature results. The presence of anharmonic effects is supported by a study of the thermal expansion in the temperature range 100–260 K. A topological study of the electron density confirms a bond length alternation in the six-membered ring. The calculation of the electrostatic potential indicates that the N–H⋯S hydrogen bond is an electrostatic interaction, and that other attractive intermolecular contacts are probably dispersive. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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13 pages, 7380 KiB  
Article
The Synthesis and Characterization of a Novel One-Dimensional Bismuth (III) Coordination Polymer as a Precursor for the Production of Bismuth (III) Oxide Nanorods
by Younes Hanifehpour, Babak Mirtamizdoust, Jaber Dadashi, Ruiyao Wang, Mahboube Rezaei, Mehdi Abdolmaleki and Sang Woo Joo
Crystals 2022, 12(1), 113; https://doi.org/10.3390/cryst12010113 - 15 Jan 2022
Cited by 5 | Viewed by 2005
Abstract
A novel Bi (III) coordination compound, [Bi(HQ)(Cl)4]n ((Q = pyridine-4-carbaldehyde thiosemicarbazone), was prepared in this research using a sonochemical technique. SEM, infrared spectroscopy (IR), XRD, and single-crystal X-ray analysis were utilized to analyze the Bi(III) coordination compound. The structure determined [...] Read more.
A novel Bi (III) coordination compound, [Bi(HQ)(Cl)4]n ((Q = pyridine-4-carbaldehyde thiosemicarbazone), was prepared in this research using a sonochemical technique. SEM, infrared spectroscopy (IR), XRD, and single-crystal X-ray analysis were utilized to analyze the Bi(III) coordination compound. The structure determined using single-crystal X-ray crystallography indicates that the coordination compound is a 1D polymer in solid state and that the coordination number of bismuth (III) ions is six, (BiSCl5), with one S donor from the organic ligand and five Cl donors from anions. It is equipped with a hemidirectional coordination sphere. It is interesting that the ligand has been protonated in the course of the reaction with a Cl- ion balancing the charge. This compound’s supramolecular properties are directed and regulated by weak directional intermolecular interactions. Through π–π stacking interactions, the chains interact with one another, forming a 3D framework. Thermolysis of the compound at 170 °C with oleic acid resulted in the formation of pure phase nanosized Bi (III) oxide. SEM technique was used to examine the morphology and size of the bismuth (III) oxide product produced. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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15 pages, 2203 KiB  
Article
Synthesis, Crystal Structure, Hirshfeld Surface Analysis and Docking Studies of a Novel Flavone–Chalcone Hybrid Compound Demonstrating Anticancer Effects by Generating ROS through Glutathione Depletion
by Soon Young Shin, Euitaek Jung, Yoongho Lim, Ha-Jin Lee, Ji Hyun Rhee, Miri Yoo, Seunghyun Ahn and Dongsoo Koh
Crystals 2022, 12(1), 108; https://doi.org/10.3390/cryst12010108 - 14 Jan 2022
Cited by 4 | Viewed by 1623
Abstract
The flavone–chalcone hybrid compound, (E)-6-bromo-3-(3-(2-methoxyphenyl)-3-oxoprop-1-enyl)-4H-chromen-4-one (3), was synthesized and its three dimensional structure was identified by X-ray crystallography. The compound 3, C19H13BrO4, was crystallized in the triclinic space group P-1 with the [...] Read more.
The flavone–chalcone hybrid compound, (E)-6-bromo-3-(3-(2-methoxyphenyl)-3-oxoprop-1-enyl)-4H-chromen-4-one (3), was synthesized and its three dimensional structure was identified by X-ray crystallography. The compound 3, C19H13BrO4, was crystallized in the triclinic space group P-1 with the following cell parameters: a = 8.2447(6) Å; b = 8.6032(6) Å; c = 11.7826(7) Å; α = 92.456(2)°; β = 91.541(2)°; γ = 106.138(2)°; V = 801.42(9) Å3 and Z = 2. In an asymmetric unit, two molecules are packed by a pi–pi stacking interaction between two flavone rings that are 3.790 Å apart from each other. In the crystal, two hydrogen bonds form inversion dimers and these dimers are extended along the a axis by another hydrogen bond. Hirshfeld analysis revealed that the H–H (34.3%), O–H (19.2%) and C–H (16.7%) intermolecular contacts are the major dominants, while the C–O (6.7%) and C–C (6.5%) are minor dominants. When HCT116 cells were treated with various concentrations of hybrid compound 3, reduced cell viability and induced apoptosis in HCT116 cells were observed in a dose-dependent manner. The treatment of HCT116 colon cancer cells with compound 3, decreased the intracellular glutathione (GSH) levels and generated a reactive oxygen species (ROS). In silico docking experiments between the compound 3 and glutathione S-transferase (GST) containing glutathione were performed to confirm whether the compound 3 binds to glutathione. Their binding energy ranged from −6.6 kcal/mol to −5.0 kcal/mol, and the sulfur of glutathione is very close to the Michael acceptor regions of the compound 3, so it is expected that they would easily react with each other. Compound 3 may be a promising novel anticancer agent by ROS generation through glutathione depletion. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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19 pages, 4516 KiB  
Article
Molecular Recognition and Shape Studies of 3- and 4-Substituted Diarylamide Quasiracemates
by Ali K. Brandt, Derek J. Boyle, Jacob P. Butler, Abigail R. Gillingham, Scott E. Penner, Jacqueline M. Spaniol, Alaina K. Stockdill, Morgan M. Vanderwall, Almat Yeraly, Diana R. Schepens and Kraig A. Wheeler
Crystals 2021, 11(12), 1596; https://doi.org/10.3390/cryst11121596 - 20 Dec 2021
Cited by 1 | Viewed by 2340
Abstract
Families of quasiracemic materials constructed from 3- and 4-substituted chiral diarylamide molecular frameworks were prepared, where the imposed functional group differences systematically varied from H to CF3–9 unique components for each isomeric framework. Cocrystallization from the melt via hot stage thermomicroscopy [...] Read more.
Families of quasiracemic materials constructed from 3- and 4-substituted chiral diarylamide molecular frameworks were prepared, where the imposed functional group differences systematically varied from H to CF3–9 unique components for each isomeric framework. Cocrystallization from the melt via hot stage thermomicroscopy using all possible racemic and quasiracemic combinations probed the structural boundaries of quasiracemate formation. The crystal structures and lattice energies (differential scanning calorimetry and lattice energy calculations) for many of these systems showed that quasienantiomeric components organize with near inversion symmetry and lattice energetics closely resembling those found in the racemic counterparts. This study also compared the shape space of pairs of quasienantiomers using an in silico alignment-based method to approximate the differences in molecular shape and provide a diagnostic tool for quasiracemate prediction. Comparing these results to our recent report on related 2-substituted diarylamide quasiracemates shows that functional group position can have a marked effect on quasiracemic behavior and provide critical insight to a more complete shape space, essential for defining molecular recognition processes. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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16 pages, 9440 KiB  
Article
Cocrystals versus Salts of Fluorescein
by Mihai Răducă and Augustin M. Mădălan
Crystals 2021, 11(10), 1217; https://doi.org/10.3390/cryst11101217 - 09 Oct 2021
Cited by 2 | Viewed by 1896
Abstract
A series of nitrogen-containing organic molecules (4,4’-bipyridyl; trans-1,2-bis(4-pyridyl)ethylene; 1,2-bis(4-pyridyl)ethane; 4-aminopyridine and trans-1,4-diaminocyclohexane) was envisaged for cocrystallization experiments together with fluorescein. These compounds, containing pyridyl or/and amino nitrogen atoms, can act either as hydrogen bond acceptors for the phenol groups of fluorescein-generating [...] Read more.
A series of nitrogen-containing organic molecules (4,4’-bipyridyl; trans-1,2-bis(4-pyridyl)ethylene; 1,2-bis(4-pyridyl)ethane; 4-aminopyridine and trans-1,4-diaminocyclohexane) was envisaged for cocrystallization experiments together with fluorescein. These compounds, containing pyridyl or/and amino nitrogen atoms, can act either as hydrogen bond acceptors for the phenol groups of fluorescein-generating cocrystals or as proton acceptors forming organic salts. Five cocrystals were obtained with the partners containing only pyridyl groups: {(H2Fl)2(bipy)} (1); {(H2Fl)2(bipy)(MeOH)2} (2); {(H2Fl)2(bpete)(EtOH)2} (3); {(H2Fl)(bpete)} (4); {(H2Fl)(bpeta)} (5). The compounds bearing amino groups deprotonate fluorescein producing salts: [(HFl)(Hampy)]∙2H2O (6); [(HFl)(Hampy)] (7); [(Fl)(H2diach)]∙3H2O (8); [(HFl)2(H2diach)]∙2H2O∙EtOH (9); and [(HFl)2(Fl)2(H2diach)3]∙4H2O (10). Optical properties of the cocrystals and salts were investigated. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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17 pages, 4123 KiB  
Article
The Polymorphism of 2-Benzoyl-N,N-diethylbenzamide
by Lygia S. de Moraes, Jie Liu, Elumalai Gopi, Ryusei Oketani, Alan R. Kennedy and Yves H. Geerts
Crystals 2021, 11(8), 1004; https://doi.org/10.3390/cryst11081004 - 22 Aug 2021
Cited by 1 | Viewed by 2478
Abstract
The crystal structures of two new polymorphs of 2-benzoyl-N,N-diethylbenzamide were obtained after recrystallization trials with different solvents. The new forms II and III were monoclinic and crystallized in the same space group with similar a, b and c lengths but [...] Read more.
The crystal structures of two new polymorphs of 2-benzoyl-N,N-diethylbenzamide were obtained after recrystallization trials with different solvents. The new forms II and III were monoclinic and crystallized in the same space group with similar a, b and c lengths but different β angles. The forms had no conformation differences within themselves; however, the long-range packing (>two unit cells) was not isostructural. In comparison with the previously published crystal structure, form I, different conformations and packing arrangements were observed. The new form II was thermally characterized and stable at room temperature, when heated up to its melting point and when cooled to −170 °C. Additionally, once form II was re-heated, a fourth form is observed after a phase transition from the monoclinic to the orthorhombic crystal systems, form IV. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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20 pages, 3251 KiB  
Article
Spin-Crossover in Iron(II) Complexes of N,N′-Disubstituted 2,6-Bis(Pyrazol-3-yl)Pyridines: An Effect of a Distal Substituent in the 2,6-Dibromophenyl Group
by Igor A. Nikovskiy, Alexander V. Polezhaev, Valentin V. Novikov, Dmitry Yu. Aleshin, Rinat R. Aysin, Elizaveta K. Melnikova, Luca M. Carrella, Eva Rentschler and Yulia V. Nelyubina
Crystals 2021, 11(8), 922; https://doi.org/10.3390/cryst11080922 - 08 Aug 2021
Cited by 5 | Viewed by 2144
Abstract
A series of new bis(pyrazol-3-yl)pyridines (LR) N,N′-disubstituted by 4-functionalized 2,6-dibromophenyl groups have been synthesized to study the effect of a distal substituent on the spin-crossover (SCO) behaviour of the iron(II) complexes [Fe(LR)2](ClO4)2 [...] Read more.
A series of new bis(pyrazol-3-yl)pyridines (LR) N,N′-disubstituted by 4-functionalized 2,6-dibromophenyl groups have been synthesized to study the effect of a distal substituent on the spin-crossover (SCO) behaviour of the iron(II) complexes [Fe(LR)2](ClO4)2 by variable-temperature magnetometry, NMR spectroscopy, and X-ray diffraction. The SCO-assisting tendency of the substituents with different electronic and steric properties (i.e., the bromine atom and the methyl group) in the para-position of the 2,6-dibromophenyl group is discussed. Together with earlier reported SCO-active iron(II) complexes with N,N′-disubstituted bis(pyrazol-3-yl)pyridines, these new complexes open the way for this family of SCO compounds to emerge as an effective ‘tool’ in revealing structure–function relations, a prerequisite for successful molecular design of switchable materials for future breakthrough applications in sensing, switching, and memory devices. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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10 pages, 1773 KiB  
Article
Pressure-Tuned Superconducting Dome in Chemically-Substituted κ-(BEDT-TTF)2Cu2(CN)3
by Yohei Saito, Anja Löhle, Atsushi Kawamoto, Andrej Pustogow and Martin Dressel
Crystals 2021, 11(7), 817; https://doi.org/10.3390/cryst11070817 - 14 Jul 2021
Cited by 4 | Viewed by 2580
Abstract
The quantum spin liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 has been established as the prime example of a genuine Mott insulator that can be tuned across the first-order insulator–metal transition either by chemical substitution or by physical pressure. Here, we [...] Read more.
The quantum spin liquid candidate κ-(BEDT-TTF)2Cu2(CN)3 has been established as the prime example of a genuine Mott insulator that can be tuned across the first-order insulator–metal transition either by chemical substitution or by physical pressure. Here, we explore the superconducting state that occurs at low temperatures, when both methods are combined, i.e., when κ-[(BEDT-TTF)1x(BEDT-STF)x]2Cu2(CN)3 is pressurized. We discovered superconductivity for partial BEDT-STF substitution with x = 0.10–0.12 even at ambient pressure, i.e., a superconducting state is realized in the range between a metal and a Mott insulator without magnetic order. Furthermore, we observed the formation of a superconducting dome by pressurizing the substituted crystals; we assigned this novel behavior to disorder emanating from chemical tuning. Full article
(This article belongs to the Special Issue Feature Papers in Organic Crystalline Materials)
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