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Crystal structures of aminopyridine–succinate salts (1–3) were solved by single crystal X-ray diffraction where salt bridge (SB) interactions between the succinate and protonated aminopyridine dominated their supramolecular architecture. X-ray crystallography reveals that compounds 1 (hydrogensuccinate 2-amino-5-methylpyridinium salt) and 2 (hydrogensuccinate 2-amino-4-methylpyridinium salt) exhibit C–H…SB…π+ assemblies, while compound 3 (succinato-aminopyridinium salt) displays unique N–H…SB…lone pair (l)p networks in the solid state. These unexplored extended networks are described and investigated for the first time in crystalline structures. Our study also describes the duality of the salt bridge in establishing π-facial interactions with electron rich and/or electron poor moieties depending on the positive or negative nature of the SB counterpart that interacts with the SB surface. The theoretical study combines an energetic investigation of the noncovalent forces that contribute to the extended supramolecular network and the characterization of the diverse interactions by means of Bader's theory of “atoms in molecules” (AIM) and the NCIplot index. [ABSTRACT FROM AUTHOR]

Abstract: A mononuclear CuII complex [Cu(IDA)(2,2′-dypam)(H2O)]·H2O (1) where H2IDA and 2,2′-dypam are iminodiacetic acid and 2,2´-dipyridylamine, respectively, has been synthesized and characterized by X-ray single crystal structure analysis. The Cu(II) atom exhibits an unsymmetrical elongated octahedral coordination type 4+1+1. X-ray crystallography reveals that complex (1) has an unprecedented fac-O2 +N(apical) IDA conformation, in the trans-site of Cu–N (IDA-like) bond, in contrast with structural co-relations for complexes with Cu/(IDA or IDA-like)/N-heterocyclic donor ratio 1/1/2 and closely related compounds fac-NO+O(apical) IDA-like conformation and one N-heterocyclic donor in the trans-site to the Cu–N (IDA-like) bond. These findings are attributed to the influence of π–π stacking, C–H⋯π interactions in the molecular recognition process. Moreover, the aromatic moieties of 2,2′-dypam are engaged in carbonyl⋯π interaction with the non-coordinated carbonyl groups of IDA ligand and giving rise to a remarkable supramolecular carbonyl–π/π–π/π–carbonyl interactions. [Copyright &y& Elsevier]

The supramolecular frameworks of two metal complexes with 1,3-diamino-2-hydroxypropanetetraacetic acid (H 4 Hpdta) have been explored in the context of crystal engineering, and the noncovalent interactions are further characterized by Bader's quantum theory of "atoms-in-molecules" (QTAIM), Noncovalent Interaction (NCI) plot index and Scatter plot. [Display omitted] A new 1,3-diamino-2-hydroxypropanetetraacetate copper complex (1) [{Cu(Hpdta)}{Cu(H 2 O) 6 }] has been synthesized and structurally characterized by single crystal X-ray diffraction and compared with a similar cobalt complex (2) of H 4 Hpdta (H 4 Hpdta = 1,3-diamino-2-hydroxypropanetetraacetic acid) retrieved from CSD (CSD ref code: TELBAN) with a detailed analysis of intermolecular interactions. X-ray crystallography reveals that both complexes are stabilized through C−H⋯O and O−H⋯O interactions generating different supramolecular networks. Detailed analysis of Hirshfeld surfaces and 2D fingerprint plot has been carried out for the title complexes to quantify the intermolecular interactions. Further, the noncovalent interactions are characterized through the Bader's theory of 'Atoms in Molecules' (AIM) and noncovalent interaction (NCI) plot index. At the bond critical point (BCP), the electron density (ρ BCP) and the Laplacian of electron density ( ∇ 2 (ρ BCP)) differ significantly for strong and weak noncovalent interactions. The dissociation energies are evaluated for validating the intermolecular interactions required to stabilize the complexes. The analysis of topological parameters extracted from AIM calculation characterized the interactions as closed-shell interactions. [ABSTRACT FROM AUTHOR]

The synthesis and X-ray structural characterization of two silver(I) coordination polymers, [Ag2(bpp)2(Phdac)]·5H2O (1) and [Ag2(bpp)(HSSal)] (2), are reported, where bpp = 4,4′-trimethylene dipyridine, H2Phdac = 1,4-phenylenediacetic acid, and H3SSal = 5-sulfosalicylic acid. X-ray crystallography reveals that the structures are stabilized through hydrogen bonding interactions. The C–H⋯πand metal⋯πinteractions of aromatic molecules play a crucial role in building a layered framework. Intricate combinations of the weak non-covalent interactions have been analyzed to explore cooperativity and competitiveness in the solid-state structures. [ABSTRACT FROM AUTHOR]

• New binuclear monooxo, dioxo and tetramolecular tetraoxo bridging molybdenum(VI) complexes with ONS donor ligand has been synthesized. • Complexes give rise to interesting supramolecular architectures. • Hirshfeld surface analysis and fingerprint plots have been done for better understanding of non-covalent interactions. • 'Atoms in molecules' (QTAIM) along with 'non-covalent interaction' (NCI) plot index analyses have also been carried out. New Binuclear monooxo, Mo 2 O 4 L 2 1(H 2 O)CHCl 3 (1), tetranuclear tetraoxo, Mo 4 O 8 L 4 1 (2) and binuclear dioxo, Mo 2 O 4 L 2 2 (3) bridged molybdenum(VI) complexes have been synthesized using two diprotic tridentate ONS donor Schiff base ligands H 2 L1 and H 2 L2 (H 2 L1 = S - benzyl-β-N-(2-hydroxyphenyl) methylene dithiocarbazate and H 2 L2 = S - benzyl-β-N-(5‑bromo-2-hydroxyphenyl) methylene dithiocarbazate. All the three complexes have been characterized by elemental analyses and IR, UV–vis and 1H NMR spectroscopies and their crystal structures were solved by single crystal X-ray diffraction technique. Complexes (1) and (3) crystallized in triclinic space group P-1 and complex (2) in monoclinic space group P2 1 /n. Complexes 1, 2 and 3 exhibit distorted octahedral geometry around Mo(VI) center. X-ray crystallography reveals that in the crystal packing of the complexes C–H···O, O–H···O, O–H···N, C–X···π (X = Br) and π···π stacking interactions cooperatively take part. A detailed analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions which are crucial in building different supramolecular architectures of three molybdenum complexes. Crystal structure analysis supported with the Hirshfeld surface and fingerprint plots enabled the identification of the significant intermolecular interactions. The intermolecular interactions are further characterized by analyzing the topological parameters through Bader's theory of 'atoms in molecule' (QTAIM) along with the 'non-covalent interaction' (NCI) plot index. The investigation of topological parameters of electron density at the (3, −1) bond critical point classified the interactions as 'closed-shell' interactions. Using two diprotic tridentate ONS donor Schiff base ligands (H 2 L1 and H 2 L2), new binuclear monooxo, Mo 2 O 4 L 2 1(H 2 O)CHCl 3 (1), tetramolecular tetraoxo, Mo 4 O 8 L 4 1 (2) and binuclear dioxo, Mo 2 O 4 L 2 2 (3) bridging molybdenum(VI) complexes have been synthesized and structurally characterized. Complexes 1–3 give rise to interesting supramolecular architectures. Hirshfeld surface, fingerprint plots and AMI (atoms in molecules) analysis has also been done in order to acquire a better understanding of non-covalent interactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• 4′-functionalized 2,2′:6′,2″-terpyridine derivatives have been synthesized and structurally characterized. • Supramolecular self-assembly of the X-ray structures are explored in detail in the context of crystal engineering. • Quantification of noncovalent interactions through Hirshfeld surface analysis. • Bader's theory of 'atoms-in-molecules'(AIM) have been performed to characterize the noncovalent interactions. • Theoretical 'Noncovalent Interaction' (NCI) plot index have been used to characterize the interactions that are involved within the structures. Three versatile 4′-substituted 2,2′:6′,2″-terpyridine compounds (1 – 3) having different substitutions (4-ethoxyphenyl, 4-methoxyphenyl and pyridyl) at 4′-position of the central pyridine ring have been synthesized and structurally characterized. Three representative crystal structures have been determined through single crystal X-ray diffraction analysis. X-ray crystallography revels that the structures are stabilized through C–H···π and π–π stacking interactions. In the solid-state, the supramolecular assemblies of the title compounds have been explored in detail. Compounds (1) and (3) exhibits both C–H···π and π–π interactions in building supramolecular assemblies whereas compound (2) exhibit π–π interaction only. All the intermolecular interactions that are involved within the structures are quantified through Hirshfeld surface analyses. The weak noncovalent interactions that played significant role in building supramolecular assemblies are further characterized by Bader's theory of 'atoms-in-molecules' (AIM). Finally, the supramolecular networks are characterized by theoretical 'Noncovalent Interaction' (NCI) plot index. The supramolecular solid-state frameworks of three 4′-functionalized 2,2′:6′,2″-terpyridine derivatives have been quantified which are further characterized theoretically by the Bader's theory of 'atoms-in-molecules'(AIM) and 'noncovalent interaction' (NCI) plot index. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Polymorphism in 2-amino-3-nitropyridine has been studied. • Supramolecular self-assemblies of the X-ray structures were explored. • Hirshfeld surface analysis was performed to quantify the noncovalent interactions. • Theoretical DFT and PIXEL methods were used to explore the interaction energies. • 'Atoms in molecule', and 'Noncovalent interaction' plot analysis were performed. Two polymorphic forms (Form–I and Form–II) of 2-amino-3-nitropyridine are structurally characterized by single crystal X-ray diffraction analysis and compared with another polymorphic form (Form–III , retrieved from CSD) with a detailed analysis of the Hirshfeld surfaces and fingerprint plots facilitating a comparison of intermolecular interactions. X-ray crystallography exposes that the polymorphs generate completely different network structures through hydrogen bonding interactions. Polymorphic Form–I exhibit a layer assembly through the cooperative face-to-face π⋯π and lone pair⋯π interactions, whereas Form–II, and Form–III displays hydrogen bonds only. A detailed investigation of Hirshfeld surface analysis reveals much more detailed scrutiny of intermolecular interactions experienced by the polymorphic forms of 2-amino-3-nitropyridine. The quantitative analysis of the interaction energies involving various noncovalent interactions was computed and compared to get a deeper insight into the role of such interactions in stabilizing the polymorphs. The interaction energies of non-covalent interactions are calculated through theoretical DFT calculations as well as the PIXEL method. The PIXEL method provides us precise interaction energy calculation with an energy decomposition scheme. Higher electrostatic interaction shows higher interaction energy while the lower interaction energy corresponds to the higher dispersive interaction. The lattice energies of the polymorphs are also obtained via the PIXEL method. The nature and strength of these interactions have been studied using Bader's quantum theory of atoms in molecules. The topological analysis unequivocally establishes the presence of (3, −1) bond critical point, suggesting that the intermolecular interactions are closed-shell interactions. The NCI (Non-covalent Interaction) plots are further employed to identify and characterize the non-covalent interactions of the polymorphs. The polymorphic forms (Form-I, Form-II and Form-III) of 2-amino-3-nitropyridine have been shown to possess distinguishable noncovalent interactions and have been investigated by Hirshfeld surface analysis, DFT, QTAIM, and NCI plot index analyses. [Display omitted] [ABSTRACT FROM AUTHOR]

A new Co(II) complex of general formula [Co(L)2] has been synthesized from a NNO tridentate Schiff base ligand, 2-[(piperidin-2-ylmethylimino)-methyl]-phenol (L). The title complex is characterized by elemental, spectroscopic, antibacterial, and single crystal X-ray structural studies. X-Ray crystallography reveals that the complex shows a distorted octahedral geometry around the Co(II) ion. The complex was tested against several bacteria and shows good antibacterial activities against almost all of the bacteria. The interactions of the title complex with calf thymus deoxyribonucleic acid (CT-DNA) have been investigated by electronic absorption and fluorescence spectroscopy, showing that the complex interacts with CT-DNA via partial intercalation. Thermogravimetric analysis (TGA) of the complex has also been reported and the result shows that the complex is thermally stable up to 134 °C. [ABSTRACT FROM AUTHOR]

A new coordination compound [HgL(ClO 4) 2 EtOH] (1) was fabricated from a mixture of Hg(NO 3) 2 and NaClO 4 with 1,2-diphenyl-1,2-bis((phenyl-(pyridin-2-yl)methylene)hydrazono)ethane (L). Complex 1 exhibits a mononuclear heteroleptic discrete structure, where the ligand L adopts a helical twist conformation. The Hg(II) cation is N 4 O 3 coordinated by four nitrogen atoms from L and by three oxygen atoms from two monocoordinated ClO 4 – anions and one ethanol molecule. The crystal structure is stabilized by the intermolecular O–H⋯O hydrogen bonds, and Cl–O⋯π Ph and C–H⋯π Ph interactions. The long Hg–N/O bonds have been analyzed in terms of coordination, semicoordination or spodium bonds using QTAIM and NCIplot index computational tools. [Display omitted] • [HgL(ClO 4) 2 EtOH] (1) was fabricated from a mixture of Hg(NO 3) 2 and NaClO 4 with L. • L stands for 1,2-diphenyl-1,2-bis((phenyl-(pyridin-2-yl)methylene)hydrazono)ethane. • Complex 1 exhibits a mononuclear heteroleptic discrete structure. • L adopts a helical twist conformation. In this work we have synthesized and characterized a new coordination compound [HgL(ClO 4) 2 EtOH] (1), fabricated from a mixture of Hg(NO 3) 2 and NaClO 4 with 1,2-diphenyl-1,2-bis((phenyl-(pyridin-2-yl)methylene)hydrazono)ethane (L). Single-crystal X-ray crystallography revealed the formation of a mononuclear heteroleptic discrete structure with one molecule [HgL(ClO 4) 2 EtOH] in the asymmetric unit. The ligand L adopts a helical twist conformation. The Hg(II) cation is coordinated by four nitrogen atoms from L and by three oxygen atoms from two monocoordinated ClO 4 – anions and one ethanol molecule. The crystal structure of 1 is stabilized by the intermolecular O–H⋯O hydrogen bonds, and Cl–O⋯π Ph and C–H⋯π Ph interactions, yielding a supramolecular 3D framework. Moreover, the long Hg–N/O bonds have been analyzed in terms of coordination, semicoordination or spodium bonds using QTAIM and NCIplot index computational tools. [ABSTRACT FROM AUTHOR]

• X-ray structure of Pent-2-ynol derivatives. • Exploration of noncovalent interactions and self-assemblies. • Bader's theory of 'atoms-in-molecules'(AIM). • 'Noncovalent Interaction' (NCI) plot index. Two new compounds namely, 6-methyl-1-(p-tolyl)hept‑3‑yne-1,5-diol (1) and N-(5‑hydroxy-1-phenylhex-3-yn-1-yl)-4-nitrobenzenesulfonamide (2) have been synthesized and structurally characterized through single-crystal X-ray diffraction analysis. X-ray crystallography reveals that the structures are stabilized through hydrogen bonds. However, compound (1) exhibits dual C–H∙∙∙π interactions. The solid-state supramolecular self-assemblies have been reconnoitered in detail for both structures. The noncovalent interactions that are exhibited by the structures are quantified through Hirshfeld surface analyses. The noncovalent interactions are characterized by Bader's theory of 'atoms-in-molecules' (AIM). Additionally, the supramolecular frameworks are further characterized by the theoretical 'Noncovalent Interaction' (NCI) plot index. The supramolecular solid-state frameworks of two pent‑2-ynol derivatives have been quantified and are theoretically characterized by Bader's theory of 'atoms-in-molecules'(AIM) and 'noncovalent interaction' (NCI) plot index. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: New iron(III) complexes of 5-methyl-3-formylpyrazole-N(4)-dimethylthiosemicarbazone (HMPZNMe2) (I) and 5-methyl-3-formylpyrazole-N(4)-diethylthiosemicarbazone (HMPZNEt2) (III), [Fe(MPZNMe2)2]NO3·H2O (II) and [Fe(MPZNEt2)2]NO3·H2O (IV), respectively, have been synthesised for the first time and physico-chemically characterised by magnetic measurements (polycrystalline state), electronic and IR spectra. Both are cationic complexes containing two monodeprotonated tridentate ligands with NNS donor sites and an anionic counterpart; the complex species behave as 1:1 electrolytes in MeOH. IR spectra (4000–200cm−1) indicate coordination to iron(III) centre via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulfur atom. X-ray crystallographic data of (II) (monoclinic, C2/c) and (IV) (, triclinic) have authenticated the FeN4S2 octahedral coordination in both complex ions, as envisaged from the spectral data. In both species, the two azomethine nitrogen atoms are trans to each other, while the pyrazolyl ring nitrogen and the thiolato sulfurs atoms are in cis positions. We further observed that both the ligands and their corresponding complexes were capable of killing HeLa cells in culture, but the cytotoxicity of the complexes was found to be greater than their corresponding ligands. Complex (II) does not have any role in cell-cycle progression, but complex (IV) arrests the M-phase to prevent cell-cycle progression. [Copyright &y& Elsevier]

· Newer ninhydrin derivatives have been studied. • Supramolecular self-assembly of the X-ray structure were explored in detail. • Hirshfeld surface and Energy framework analysis were performed. • DFT calculation were performed to explore the energetic features. • Bader's theory of "atoms-in-molecules" (AIM) have been performed. Three ninhydrin derivatives (2 – 4) have been synthesized where the reaction of ninhydrin with Meldrum's acid yielded [3.3.3] propellanoid (2) and ethyl 2,2-bis (1,3-dioxo-2,3-dihydro-1 H -inden-2-yl)acetate (3) while with malononitrile yielded a spiroindenopyran (4). The products being crystalline in nature and are characterized by single crystal X-ray diffraction in addition to other spectroscopic studies. X-ray crystallography reveals that solid-state structure of the title compounds exhibits C‒H···π, π‒π and lone-pair(l.p)···π interactions in building supramolecular assemblies. Indeed, compound (2) was stabilized through extended supramolecular C‒H···π/π‒π/π···H‒C network whereas compounds (3) and (4) are stabilized through lone-pair (l.p)···π and π‒π interaction respectively. The diverse intermolecular interactions via Hirshfeld surface analysis enables quantitative contributions to the crystal packing that exposes the similarities and differences in the interactions experienced by each compound. The distinctive energy frameworks have been calculated for individual molecules and the interaction energies suggest that the contacts are largely dispersive in nature. The binding energies associated with the non-covalent interactions observed in the crystal structures have been calculated using theoretical DFT calculations. Finally, the interplay between the interactions have been characterized by Bader's theory of "atoms-in-molecules" (AIM). Image, graphical abstract [ABSTRACT FROM AUTHOR]