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11 pages, 3212 KiB

Open AccessArticle

Tuning of the Electrostatic Potentials on the Surface of the Sulfur Atom in Organic Molecules: Theoretical Design and Experimental Assessment

by Ziyu Wang, Weizhou Wang and Hai-Bei Li

Molecules 2023, 28(9), 3919; https://doi.org/10.3390/molecules28093919 - 06 May 2023

Viewed by 1298

Abstract

Noncovalent sulfur interactions are ubiquitous and play important roles in medicinal chemistry and organic optoelectronic materials. Quantum chemical calculations predicted that the electrostatic potentials on the surface of the sulfur atom in organic molecules could be tuned through the through-space effects of suitable [...] Read more.

Noncovalent sulfur interactions are ubiquitous and play important roles in medicinal chemistry and organic optoelectronic materials. Quantum chemical calculations predicted that the electrostatic potentials on the surface of the sulfur atom in organic molecules could be tuned through the through-space effects of suitable substituents. This makes it possible to design different types of noncovalent sulfur interactions. The theoretical design was further confirmed by X-ray crystallographic experiments. The sulfur atom acts as the halogen atom acceptor to form the halogen bond in the cocrystal between 2,5-bis(2-pyridyl)-1,3,4-thiadiazole and 1,4-diiodotetrafluorobenzene, whereas it acts as the chalcogen atom donor to form the chalcogen bond in the cocrystal between 2,5-bis(3-pyridyl)-1,3,4-thiadiazole and 1,3,5-trifluoro-2,4,6-triiodobenzene. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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12 pages, 3640 KiB

Open AccessArticle

Crystal Structure, Photophysical Study, Hirshfeld Surface Analysis, and Nonlinear Optical Properties of a New Hydroxyphenylamino Meldrum’s Acid Derivative

by Wulan Zeng, Xia Wang, Tao Zhou and Yunju Zhang

Molecules 2023, 28(5), 2181; https://doi.org/10.3390/molecules28052181 - 26 Feb 2023

Viewed by 1079

Abstract

The structural, photophysical, and vibrational properties of a new hydroxyphenylamino Meldrum’s acid derivative, 3-((2-hydroxyphenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione (HMD), were studied. The comparison of experimental and theoretical vibrational spectra can help understand basic vibration patterns and provides a better interpretation of IR spectra. The UV–Vis spectrum of [...] Read more.

The structural, photophysical, and vibrational properties of a new hydroxyphenylamino Meldrum’s acid derivative, 3-((2-hydroxyphenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione (HMD), were studied. The comparison of experimental and theoretical vibrational spectra can help understand basic vibration patterns and provides a better interpretation of IR spectra. The UV–Vis spectrum of HMD was computed using density functional theory (DFT)/B3LYP/6-311 G(d,p) basis set in the gas state, and the maximum wavelength was in accord with the experimental data. The molecular electrostatic potential (MEP) and Hirshfeld surface analysis confirmed O(1)–H(1A)···O(2) intermolecular hydrogen bonds in the HMD molecule. The natural bond orbital (NBO) analysis provided delocalizing interactions between π→π* orbitals and n→σ*/π* charge transfer transitions. Finally, the thermal gravimetric (TG)/differential scanning calorimeter (DSC) and the non-linear optical (NLO) properties of HMD were also reported. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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22 pages, 6382 KiB

Open AccessArticle

A 12-Connected [Y₄((μ₃-OH)₄]⁸⁺ Cluster-Based Luminescent Metal-Organic Framework for Selective Turn-on Detection of F⁻ in H₂O

by Juan Li, Airong Wang, Shiming Qiu, Xiaoli Wang and Jiaming Li

Molecules 2023, 28(4), 1893; https://doi.org/10.3390/molecules28041893 - 16 Feb 2023

Cited by 3 | Viewed by 1946

Abstract

Fluoride ion (F⁻) is one of the most hazardous elements in potable water. Over intake of F⁻ can give rise to dental fluorosis, kidney failure, or DNA damage. As a result, developing affordable, equipment-free and credible approaches for F⁻ [...] Read more.

Fluoride ion (F⁻) is one of the most hazardous elements in potable water. Over intake of F⁻ can give rise to dental fluorosis, kidney failure, or DNA damage. As a result, developing affordable, equipment-free and credible approaches for F⁻ detection is an important task. In this work, a new three dimensional rare earth cluster-based metal-organic framework assembled from lanthanide Y(III) ion, and a linear multifunctional ligand 3-nitro-4,4′-biphenyldicarboxylic acid, formulated as {[Y(μ₃-OH)]₄[Y(μ₃-OH)(μ₂-H₂O)_0.25(H₂O)_0.5]₄[μ₄-nba]₈}_n (1), where H₂nba = 3-nitro-4,4′-biphenyldicarboxylic acid, has been hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), power X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. X-ray diffraction structural analysis revealed that 1 crystallizes in tetragonal system with P

\bar{4}

2₁m space group, and features a 3D framework with 1D square 18.07(3)² Å² channels running along the [0,0,1] or c-axis direction. The structure of 1 is built up of unusual eight-membered rings formed by two types of {Y₄O₄} clusters connected to each other via 12 μ₄-nba²⁻ and 4 μ₃-OH⁻ ligands. Three crystallographic independent Y³⁺ ions display two coordinated configurations with a seven-coordinated distorted monocapped trigonal-prism (YO₇) and an eight-coordinated approximately bicapped trigonal-prism (YO₈). 1 is further stabilized through O-H⋯O, O-H⋯N, C-H⋯O, and π⋯π interactions. Topologically, MOF 1 can be simplified as a 12-connected 2-nodal Au₄Ho topology with a Schläfli symbol {4²⁰·6²⁸·8¹⁸}{4³}₄ or a 6-connected uninodal pcu topology with a Schläfli symbol {4¹²·6³}. The fluorescent sensing application of 1 was investigated to cations and anions in H₂O. 1 exhibits good luminescence probing turn-on recognition ability toward F⁻ and with a limit detection concentration of F⁻ down to 14.2 μM in aqueous solution (K_ec = 11403 M⁻¹, R² = 0.99289, σ = 0.0539). The findings here provide a feasible detection platform of LnMOFs for highly sensitive discrimination of F⁻ in aqueous media. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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17 pages, 4311 KiB

Open AccessArticle

Manipulation of Morphology, Particle Size of Barium Sulfate and the Interacting Mechanism of Methyl Glycine Diacetic Acid

by Jing Li, Yanan Zhou, Jingkang Wang, Na Wang, Jingtao Bi, Xin Li, Kui Chen and Hongxun Hao

Molecules 2023, 28(2), 726; https://doi.org/10.3390/molecules28020726 - 11 Jan 2023

Cited by 1 | Viewed by 1529

Abstract

In this paper, methyl glycine diacetic acid (MGDA) was found to have great influence on the morphology and particle size of barium sulfate. The effects of additive, concentration, value of pH and reaction temperature on the morphology and particle size of barium sulfate [...] Read more.

In this paper, methyl glycine diacetic acid (MGDA) was found to have great influence on the morphology and particle size of barium sulfate. The effects of additive, concentration, value of pH and reaction temperature on the morphology and particle size of barium sulfate were studied in detail. The results show that the concentration of reactant and temperature have little effect on the particle size of barium sulfate. However, the pH conditions of the solution and the dosage of MGDA can apparently affect the particle size distribution of barium sulfate. The particle size of barium sulfate particles increases and the morphology changes from polyhedral to rice-shaped with the decreasing of the dosage of MGDA. In solution with higher pH, smaller and rice-shaped barium sulfate was obtained. To investigate the interacting mechanism of MGDA, the binding energy between MGDA and barium sulfate surface was calculated. It was found that the larger absolute value of the binding energy would result in stronger growth inhibition on the crystal face. Finally, the experimental data and theoretical calculations were combined to elucidate the interacting mechanism of the additive on the morphology and particle size of barium sulfate. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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17 pages, 5523 KiB

Open AccessArticle

Intermolecular Interactions and Charge Resonance Contributions to Triplet and Singlet Exciton States of Oligoacene Aggregates

by Yasi Dai, Alessandro Calzolari, Maria Zubiria-Ulacia, David Casanova and Fabrizia Negri

Molecules 2023, 28(1), 119; https://doi.org/10.3390/molecules28010119 - 23 Dec 2022

Cited by 1 | Viewed by 1751

Abstract

Intermolecular interactions modulate the electro-optical properties of molecular materials and the nature of low-lying exciton states. Molecular materials composed by oligoacenes are extensively investigated for their semiconducting and optoelectronic properties. Here, we analyze the exciton states derived from time-dependent density functional theory (TDDFT) [...] Read more.

Intermolecular interactions modulate the electro-optical properties of molecular materials and the nature of low-lying exciton states. Molecular materials composed by oligoacenes are extensively investigated for their semiconducting and optoelectronic properties. Here, we analyze the exciton states derived from time-dependent density functional theory (TDDFT) calculations for two oligoacene model aggregates: naphthalene and anthracene dimers. To unravel the role of inter-molecular interactions, a set of diabatic states is selected, chosen to coincide with local (LE) and charge-transfer (CT) excitations within a restricted orbital space including two occupied and two unoccupied orbitals for each molecular monomer. We study energy profiles and disentangle inter-state couplings to disclose the (CT) character of singlet and triplet exciton states and assess the influence of inter-molecular orientation by displacing one molecule with respect to the other along the longitudinal translation coordinate. The analysis shows that (CT) contributions are relevant, although comparably less effective for triplet excitons, and induce a non-negligible mixed character to the low-lying exciton states for eclipsed monomers and for small translational displacements. Such (CT) contributions govern the L_a/L_b state inversion occurring for the low-lying singlet exciton states of naphthalene dimer and contribute to the switch from H- to J-aggregate type of the strongly allowed B_b transition of both oligoacene aggregates. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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23 pages, 8246 KiB

Open AccessArticle

Some Theoretical and Experimental Evidence for Particularities of the Siloxane Bond

by Alexandru-Constantin Stoica, Madalin Damoc, Corneliu Cojocaru, Alina Nicolescu, Sergiu Shova, Mihaela Dascalu and Maria Cazacu

Molecules 2022, 27(23), 8563; https://doi.org/10.3390/molecules27238563 - 05 Dec 2022

Viewed by 1349

Abstract

The specific features of the siloxane bond unify the compounds based on it into a class with its own chemistry and unique combinations of chemical and physical properties. An illustration of their chemical peculiarity is the behavior of 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane (AEAMDS) in the reaction [...] Read more.

The specific features of the siloxane bond unify the compounds based on it into a class with its own chemistry and unique combinations of chemical and physical properties. An illustration of their chemical peculiarity is the behavior of 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane (AEAMDS) in the reaction with carbonyl compounds and metal salts, by which we obtain the metal complexes of the corresponding Schiff bases formed in situ. Depending on the reaction conditions, the fragmentation of this compound takes place at the siloxane bond, but, in most cases, it is in the organic moieties in the β position with respect to the silicon atom. The main compounds that were formed based on the moieties resulting from the splitting of this diamine were isolated and characterized from a structural point of view. Depending on the presence or not of the metal salt in the reaction mixture, these are metal complexes with organic ligands (either dangling or not dangling silanol tails), or organic compounds. Through theoretical calculations, electrons that appear in the structure of the siloxane bond in different contexts and that lead to such fragmentations have been assessed. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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19 pages, 5243 KiB

Open AccessArticle

[M^II(H₂dapsc)]-[Cr(CN)₆] (M = Mn, Co) Chain and Trimer Complexes: Synthesis, Crystal Structure, Non-Covalent Interactions and Magnetic Properties

by Valentina D. Sasnovskaya, Leokadiya V. Zorina, Sergey V. Simonov, Artem D. Talantsev and Eduard B. Yagubskii

Molecules 2022, 27(23), 8518; https://doi.org/10.3390/molecules27238518 - 03 Dec 2022

Cited by 1 | Viewed by 1583

Abstract

Four new heterometallic complexes combining [M^II(H₂dapsc)]²⁺ cations with the chelating H₂dapsc {2,6-diacetylpyridine-bis(semicarbazone)} Schiff base ligand and [Cr(CN)₆]³⁻ anion were synthesized: {[M^II(H₂dapsc)]Cr^III(CN)₆K(H₂O)_2.5(EtOH) [...] Read more.

Four new heterometallic complexes combining [M^II(H₂dapsc)]²⁺ cations with the chelating H₂dapsc {2,6-diacetylpyridine-bis(semicarbazone)} Schiff base ligand and [Cr(CN)₆]³⁻ anion were synthesized: {[M^II(H₂dapsc)]Cr^III(CN)₆K(H₂O)_2.5(EtOH)_0.5}_n·1.2n(H₂O), M = Mn (1) and Co (2), {[Mn(H₂dapsc)]₂Cr(CN)₆(H₂O)₂}Cl·H₂O (3) and {[Co(H₂dapsc)]₂Cr(CN)₆(H₂O)₂}Cl·2EtOH·3H₂O (4). In all the compounds, M(II) centers are seven-coordinated by N₃O₂ atoms of H₂dapsc in the equatorial plane and N or O atoms of two apical –CN/water ligands. Crystals 1 and 2 are isostructural and contain infinite negatively charged chains of alternating [M^II(H₂dapsc)]²⁺ and [Cr^III(CN)₆]³⁻ units linked by CN-bridges. Compounds 3 and 4 consist of centrosymmetric positively charged trimers in which two [M^II(H₂dapsc)]²⁺ cations are bound through one [Cr^III(CN)₆]³⁻ anion. All structures are regulated by π-stacking of coplanar H₂dapsc moieties as well as by an extensive net of hydrogen bonding. Adjacent chains in 1 and 2 interact also by coordination bonds via a pair of K⁺ ions. The compounds containing Mn^II (1, 3) and Co^II (2, 4) show a significant difference in magnetic properties. The ac magnetic measurements revealed that complexes 1 and 3 behave as a spin glass and a field-induced single-molecule magnet, respectively, while 2 and 4 do not exhibit slow magnetic relaxation in zero and non-zero dc fields. The relationship between magnetic properties and non-covalent interactions in the structures 1–4 was traced. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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9 pages, 1161 KiB

Open AccessArticle

One-Dimensional Iodoantimonate(III) and Iodobismuthate(III) Supramolecular Hybrids with Diiodine: Structural Features, Stability and Optical Properties

by Nikita A. Korobeynikov, Andrey N. Usoltsev, Pavel A. Abramov, Maxim N. Sokolov and Sergey A. Adonin

Molecules 2022, 27(23), 8487; https://doi.org/10.3390/molecules27238487 - 02 Dec 2022

Cited by 2 | Viewed by 941

Abstract

Two isostructural pairs of supramolecular iodoantimonate(III) and iodobismuthate(III) complexes with I₂ units “trapped” in solid state via halogen bonding—Cat₃[[M₂I₉](I₂)} (Cat = tetramethylammonium and 1-methylpyridinium, M = Sb(III) and Bi(III)) were prepared. For all compounds, [...] Read more.

Two isostructural pairs of supramolecular iodoantimonate(III) and iodobismuthate(III) complexes with I₂ units “trapped” in solid state via halogen bonding—Cat₃[[M₂I₉](I₂)} (Cat = tetramethylammonium and 1-methylpyridinium, M = Sb(III) and Bi(III)) were prepared. For all compounds, values of optical band gaps were determined, together with thermal stability; the complexes were additionally characterized by Raman spectroscopy. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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11 pages, 2136 KiB

Open AccessArticle

The Influence of the Halide in the Crystal Structures of 1-(2,3,5,6-Tetrafluoro-4-pyridyl)-3-benzylimidazolium Halides

by Udari A. I. Acharige and Graham C. Saunders

Molecules 2022, 27(21), 7634; https://doi.org/10.3390/molecules27217634 - 07 Nov 2022

Viewed by 1001

Abstract

The crystal structures of 1-(2,3,5,6-tetrafluoro-4-pyridyl)-3-benzylimidazolium chloride (1) and iodide (3) have been determined by single crystal X-ray diffraction. The crystal structure of 1 is similar to that of the bromide salt (2), possessing anion···C₅F₅ [...] Read more.

The crystal structures of 1-(2,3,5,6-tetrafluoro-4-pyridyl)-3-benzylimidazolium chloride (1) and iodide (3) have been determined by single crystal X-ray diffraction. The crystal structure of 1 is similar to that of the bromide salt (2), possessing anion···C₅F₅N···C₆H₅ motifs, whilst that of 3 contains columns of alternating iodide anions and parallel tetrafluoropyridyl rings. All three crystal structures possess C(1)–H∙∙∙X⁻ and C(2)–H∙∙∙X⁻ hydrogen bonding. DFT calculations reveal that the strengths of the hydrogen bonding interactions lie in the order C(1)–H···X⁻ > C(3)–H···X⁻ > C(2)–H···X⁻ for the same halide (X⁻) and Cl⁻ > Br⁻ > I⁻ for each position. It is suggested that salt 3 adopts a different structure to salts 1 and 2 because of the larger size of iodide. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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26 pages, 6717 KiB

Open AccessArticle

Chemical Bonding Effects and Physical Properties of Noncentrosymmetric Hexagonal Fluorocarbonates ABCO₃F (A: K, Rb, Cs; B: Mg, Ca, Sr, Zn, Cd)

by Yuri Zhuravlev and Victor Atuchin

Molecules 2022, 27(20), 6840; https://doi.org/10.3390/molecules27206840 - 12 Oct 2022

Cited by 3 | Viewed by 1449

Abstract

The present work applied the methods of density functional theory and the van der Waals interaction PBE + D3(BJ) on the basis of localized orbitals of the CRYSTAL17 package. It featured the effect of interactions between structural elements of fluorocarbonates ABCO₃F [...] Read more.

The present work applied the methods of density functional theory and the van der Waals interaction PBE + D3(BJ) on the basis of localized orbitals of the CRYSTAL17 package. It featured the effect of interactions between structural elements of fluorocarbonates ABCO₃F (A: K, Rb, Cs; B: Mg, Ca, Sr, Zn, Cd) on their elastic and vibrational properties. The hexagonal structures proved to consist of alternating ···B-CO₃··· and ···A-F··· layers in planes ab, interconnected along axis c by infinite chains ···F-B-F···, where cations formed polyhedra AO_nF₃ and BO_mF₂. The calculations included the band energy structure, the total and partial density of electron states, the energy and band widths of the upper ns- and np-states of alkali and alkaline-earth metals, as well as nd-zinc and nd-cadmium. For hydrostatic compression, we calculated the parameters of the Birch–Murnaghan equation of state and the linear compressibility moduli along the crystal axes and bond lines. We also defined the elastic constants of single crystals to obtain the Voigt–Reuss–Hill approximations for the elastic moduli of polycrystalline materials. The study also revealed the relationship between the elastic properties and the nature of the chemical bond. Hybrid functional B3LYP made it possible to calculate the modes of normal long-wavelength oscillations, which provided the spectra of infrared absorption and Raman scattering. Intramolecular modes ν1 and ν4 with one or two maxima were found to be intense, and their relative positions depended on the lengths of nonequivalent C–O bonds. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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17 pages, 2961 KiB

Open AccessArticle

Involvement of Arsenic Atom of AsF₃ in Five Pnicogen Bonds: Differences between X-ray Structure and Theoretical Models

by Steve Scheiner, Mariusz Michalczyk and Wiktor Zierkiewicz

Molecules 2022, 27(19), 6486; https://doi.org/10.3390/molecules27196486 - 01 Oct 2022

Cited by 3 | Viewed by 1580

Abstract

Bonding within the AsF₃ crystal is analyzed via quantum chemical methods so as to identify and quantify the pnicogen bonds that are present. The structure of a finite crystal segment containing nine molecules is compared with that of a fully optimized cluster [...] Read more.

Bonding within the AsF₃ crystal is analyzed via quantum chemical methods so as to identify and quantify the pnicogen bonds that are present. The structure of a finite crystal segment containing nine molecules is compared with that of a fully optimized cluster of the same size. The geometries are qualitatively different, with a much larger binding energy within the optimized nonamer. Although the total interaction energy of a central unit with the remaining peripheral molecules is comparable for the two structures, the binding of the peripherals with one another is far larger in the optimized cluster. This distinction of much stronger total binding within the optimized cluster is not limited to the nonamer but repeats itself for smaller aggregates as well. The average binding energy of the cluster rises quickly with size, asymptotically approaching a value nearly triple that of the dimer. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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20 pages, 10162 KiB

Open AccessArticle

Facile Access to 2-Selenoxo-1,2,3,4-tetrahydro-4-quinazolinone Scaffolds and Corresponding Diselenides via Cyclization between Methyl Anthranilate and Isoselenocyanates: Synthesis and Structural Features

by Vladimir K. Osmanov, Evgeniy V. Chipinsky, Victor N. Khrustalev, Alexander S. Novikov, Rizvan Kamiloglu Askerov, Alexander O. Chizhov, Galina N. Borisova, Alexander V. Borisov, Maria M. Grishina, Margarita N. Kurasova, Anatoly A. Kirichuk, Alexander S. Peregudov, Andreii S. Kritchenkov and Alexander G. Tskhovrebov

Molecules 2022, 27(18), 5799; https://doi.org/10.3390/molecules27185799 - 07 Sep 2022

Cited by 4 | Viewed by 1415

Abstract

A practical method for the synthesis of 2-selenoxo-1,2,3,4-tetrahydro-4-quinazolinone was reported. The latter compounds were found to undergo facile oxidation with H₂O₂ into corresponding diselenides. Novel organoselenium derivatives were characterized by the ¹H, ⁷⁷Se, and ¹³C NMR spectroscopies, [...] Read more.

A practical method for the synthesis of 2-selenoxo-1,2,3,4-tetrahydro-4-quinazolinone was reported. The latter compounds were found to undergo facile oxidation with H₂O₂ into corresponding diselenides. Novel organoselenium derivatives were characterized by the ¹H, ⁷⁷Se, and ¹³C NMR spectroscopies, high-resolution electrospray ionization mass spectrometry, IR, elemental analyses (C, H, N), and X-ray diffraction analysis for several of them. Novel heterocycles exhibited multiple remarkable chalcogen bonding (ChB) interactions in the solid state, which were studied theoretically. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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11 pages, 2137 KiB

Open AccessArticle

Selenium(IV) Polybromide Complexes: Structural Diversity Driven by Halogen and Chalcogen Bonding

by Nikita A. Korobeynikov, Andrey N. Usoltsev, Alexander S. Novikov, Pavel A. Abramov, Maxim N. Sokolov and Sergey A. Adonin

Molecules 2022, 27(16), 5355; https://doi.org/10.3390/molecules27165355 - 22 Aug 2022

Cited by 3 | Viewed by 1562

Abstract

Reactions between bromoselenate(IV)-containing solutions, dibromine and salts of pyridinium-family organic cations resulted in structurally diverse, bromine-rich polybromine-bromoselenates(IV): (4-MePyH)₅[Se₂Br₉][SeBr₆](Br₃)₂ (1), (2-MePyH)₂{[SeBr₆](Br₂)} (2), (PyH) [...] Read more.

Reactions between bromoselenate(IV)-containing solutions, dibromine and salts of pyridinium-family organic cations resulted in structurally diverse, bromine-rich polybromine-bromoselenates(IV): (4-MePyH)₅[Se₂Br₉][SeBr₆](Br₃)₂ (1), (2-MePyH)₂{[SeBr₆](Br₂)} (2), (PyH)₂{[SeBr₅]Br(Br₂)₂} (3), (1-MePy)₂{[SeBr₆](Br₂)} (4). The compounds feature halogen and (in the case of 3) chalcogen bonding in solid state, resulting in formation of supramolecular architectures of different dimensionality. DFT calculations allowed estimation of the energies of non-covalent interactions in 1–4; additionally, characterization by Raman spectroscopy was performed. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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13 pages, 4075 KiB

Open AccessArticle

Crystal Structure and Noncovalent Interactions of Heterocyclic Energetic Molecules

by Yan Liu, Jiake Fan, Zhongqing Xue, Yajing Lu, Jinan Zhao and Wenyan Hui

Molecules 2022, 27(15), 4969; https://doi.org/10.3390/molecules27154969 - 04 Aug 2022

Cited by 3 | Viewed by 1445

Abstract

Nitrogen-rich heterocyclic compounds are important heterocyclic substances with extensive future applications for energetic materials due to their outstanding density and excellent physicochemical properties. However, the weak intermolecular interactions of these compounds are not clear, which severely limits their widespread application. Three nitrogen-rich heterocyclic [...] Read more.

Nitrogen-rich heterocyclic compounds are important heterocyclic substances with extensive future applications for energetic materials due to their outstanding density and excellent physicochemical properties. However, the weak intermolecular interactions of these compounds are not clear, which severely limits their widespread application. Three nitrogen-rich heterocyclic compounds were chosen to detect their molecular geometry, stacking mode and intermolecular interactions by crystal structure, Hirshfeld surface, RDG and ESP. The results show that all atoms in each molecule are coplanar and that the stacking mode of the three crystals is a planar layer style. A large amount of inter- and intramolecular interaction exists in the three crystals. All principal types of intermolecular contacts in the three crystals are N···H interactions and they account for 40.9%, 38.9% and 32.9%, respectively. Hydrogen bonding, vdW interactions and steric effects in Crystal c are stronger than in Crystals a and b. The negative ESPs all concentrate on the nitrogen atoms in the three molecules. This work is expected to benefit the crystal engineering of heterocyclic energetic materials. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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15 pages, 5473 KiB

Open AccessArticle

Noncovalent Interactions and Crystal Structure Prediction of Energetic Materials

by Yan Liu, Chongwei An, Ning Liu, Minchang Wang, Baoyun Ye and Dongjie Liao

Molecules 2022, 27(12), 3755; https://doi.org/10.3390/molecules27123755 - 10 Jun 2022

Cited by 7 | Viewed by 1516

Abstract

The crystal and molecular structures, intermolecular interactions, and energy of CL-20, HATO, and FOX-7 were comparatively predicted based on molecular dynamic (MD) simulations. By comparison, the 2D fingerprint plot, Hirshfeld surface, reduced density gradient isosurface, and electrostatic potential surface were studied to detect [...] Read more.

The crystal and molecular structures, intermolecular interactions, and energy of CL-20, HATO, and FOX-7 were comparatively predicted based on molecular dynamic (MD) simulations. By comparison, the 2D fingerprint plot, Hirshfeld surface, reduced density gradient isosurface, and electrostatic potential surface were studied to detect the intermolecular interactions. Meanwhile, the effects of vacuum and different solvents on the crystal habit of CL-20, HATO, and FOX-7 were studied by AE and MAE model, respectively. The energy calculation was also analysed based on the equilibrium structures of these crystal models by MD simulations. Our results would provide fundamental insights for the crystal engineering of energetic materials. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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Jump to: Research

18 pages, 1284 KiB

Open AccessReview

Energy Electronegativity and Chemical Bonding

by Stepan S. Batsanov

Molecules 2022, 27(23), 8215; https://doi.org/10.3390/molecules27238215 - 25 Nov 2022

Cited by 6 | Viewed by 1611

Abstract

Historical development of the concept of electronegativity (EN) and its significance and prospects for physical and structural chemistry are discussed. The current cutting-edge results are reviewed: new methods of determining the ENs of atoms in solid metals and of bond polarities and effective [...] Read more.

Historical development of the concept of electronegativity (EN) and its significance and prospects for physical and structural chemistry are discussed. The current cutting-edge results are reviewed: new methods of determining the ENs of atoms in solid metals and of bond polarities and effective atomic charges in molecules and crystals. The ENs of nanosized elements are calculated for the first time, enabling us to understand their unusual reactivity, particularly the fixation of N₂ by nanodiamond. Bond polarities in fluorides are also determined for the first time, taking into account the peculiarities of the fluorine atom’s electronic structure and its electron affinity. Full article

(This article belongs to the Special Issue Covalent and Noncovalent Interactions in Crystal Chemistry)

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