Ring opening of 2,6-diaryl-3,5-diphenyl piperidine-4-one by acetic acid: Structural studies and Hirshfeld surface analysis of (E)-4-aryl-1,3-diphenylbut-3-en-2-ones

Six α,β-unsaturated carbonyl compounds have been obtained from 2,6-diaryl-3,5-diphenylpiperidine-4-one by the treatment with acetic acid. A plausible mechanism for the ring opening of 2,6-diaryl-3,5-diphenyl piperidin-4-ones is proposed. The resultant (E)-4-aryl-1,3-diphenylbut-3-en-2-ones have been characterized by ¹H and ¹³C nuclear magnetic resonance (NMR) spectral studies. One of the compounds was completely characterized by 2D NMR techniques, and structure of the compound is further proved by single-crystal X-ray diffraction (XRD) analysis. The crystal structure, three-dimensional framework of crystal, and Hirshfeld surface analysis of two of the compounds have been discussed. In the crystals, molecules are mainly linked by C H···O hydrogen bonding interactions, and this interaction forms an inversion dimer with R₂¹(6) and R₂¹(10) ring motifs in one of the compounds. Hirshfeld surface indicates the dominance of H···H contacts on the overall surface.     

One Novel Trinuclear Nickel(II) Cluster Containing a Pyramidal Ni<Subscript>3</Subscript>(<Emphasis Type="Italic">μ</Emphasis><Subscript>3</Subscript>-OH) Core: Crystal Structure and Hirshfeld Surface Analysis

One new trinuclear nickel(II) cluster with a Ni₃(μ ₃-OH) core was synthesized by the method of in situ one pot synthesis. The complex [Ni₃(μ ₃-OH)(cpza)₃]Cl₂·H₂O (1) (where Hcpza is N-(4-cyano-1H-pyrazol-3-yl)acetamide) was characterized by single-crystal X-ray diffraction methods, elemental analyses, IR spectroscopy and Hirshfeld surface analysis. For complex 1, the crystal structure is extended into 3D structure through N–H···O and O–H···Cl hydrogen bonds. According to the 3D Hirshfeld surface and 2D fingerprint plots, the main interactions in the cluster are the H···H, N···H and O···H contacts.     

Structural,Hirshfeld surface and in vitro cytotoxicity evaluation of five new N-aryl-N’-alkoxycarbonyl thiocarbamide derivatives

Abstract

Five new compounds, N-(2, 4-dichlorophenyl)-N’-(methoxycarbonyl) thiocarbamide (1), N-(2, 4-dichlorophenyl)-N’-(ethoxycarbonyl) thiocarbamide (2), N-(2, 4-dichlorophenyl)-N’-(2, 2, 2-trichloroethoxycarbonyl) thiocarbamide (3), N-(2,4-dichlrophenyl)-N’-(pentoxycarbonyl) thiocarbamide (4) and N-(4-nitrophenyl)-N’-(pentoxycarbonyl) thiocarbamide (5), have been synthesized by the reaction of various alkoxy chloroformates with 2, 4-dichloroaniline/4-nitroaniline.The molecular structures of the compounds were elucidated by using spectroscopic methods (FT-IR, ¹H and ¹³C NMR) and single-crystal X-ray structure analysis of compounds 2 and 5. Antiperiplanar orientation of C?=?O and C?=?S group across C–N bonds of thiocarbamide core may be due to the presence of intramolecular (N–H···O–C) hydrogen bond in the crystal structure of both the compounds. The presence of intermolecular interactions (C–H···S, C–H···O and N–H···S) in the molecular structure of the compounds has been studied in detail using Hirshfeld surfaces and their associated two-dimensional fingerprint plots. In vitro cytotoxicity screening of the synthesized compounds evaluated on a panel of seven human cancer cell lines (cervical carcinoma (2008, C13*), colorectal (HT29 and HCT116) and ovarian carcinoma (A2780, A2780/CP and IGROV-1)) demonstrated significant inhibitory properties.     

A Triazolate-Supported Fe<Subscript>3</Subscript>(<Emphasis Type="Italic">μ</Emphasis><Subscript><Emphasis Type="Italic">3</Emphasis></Subscript>-O) Core: Crystal Structure,Fluorescence, and Hirshfeld Surface Analysis

One new trinuclear Fe(III) cluster with a Fe₃(μ ₃-O) core was synthesized by the method of hydrothermal synthesis. The complex [Fe₃(μ ₃-O)(pmta)₆(H₂O)₃]FeCl₄·2H₂O (1) (where Hpmta is 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid) was characterized by single-crystal X-ray diffraction methods, elemental analyses, IR spectroscopy, fluorescence and Hirshfeld surface analysis. For complex 1, the crystal structure is extended into 3D structure through N–H···O and O–H···O hydrogen bonds. According to the 3D Hirshfeld surface and 2D fingerprint plots, the main interactions in the cluster are the H···H, N···H and C···H contacts.     

High pressure,a protocol to identify the weak dihydrogen bonds:experimental evidence of C–H···H–B interaction

Pressure, as a thermodynamic parameter, provides an appropriate method to detect weak intermolecular interactions. The C–H···H–B dihydrogen bond is so weak that the experimental evidence of this interaction is still limited. A combination of in situ high pressure Raman spectra and angle-dispersive X-ray diffraction(ADXRD) experiments was utilized to explore the dihydrogen bonds in dimethylamine borane(DMAB). Both Raman and ADXRD measurements suggested that the crystal structure of DMAB is stable in the pressure region from 1 atm(1 atm=1.01325×10~5 Pa) to 0.54 GPa. The red shift of CH stretching and CH_3 distortion modes gave strong evidence for the existence of C–H···H–B dihydrogen bonds. Further analysis of Raman spectra and Hirshfeld surface confirmed our proposal. This work provided a deeper understanding of dihydrogen bonds.And we wish that high pressure could be applied to identify other unconfirmed hydrogen or dihydrogen bond.     

Synthesis and crystal structure of 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate

The compound 2-{5-[2-(2,6-dichlorophenylamino)benzyl]-4-p-tolyl-4H-1,2,4-triazol-3-ylthio}acetate has been prepared and characterized by IR, ¹H NMR, ¹³C NMR and mass spectra. The crystal and molecular structure were further confirmed using single crystal X-ray diffraction. The crystal structure has been found to be stabilized by intermolecular C–H···O interaction generating bifurcated hydrogen bonds whereas the C–H···N interactions generate chain of molecules. The intramolecular N–H···N hydrogen bond forms a ring with S(7) graph-set motif.     

Mixed Ligand Palladium(Ⅱ) Complex with NS-Bidentate S-Allyldithiocarbazate Schiff Base: Synthesis, Spectral Char-acterization, Crystal Structure and Decoding Intermolecular Interactions with Hirshfeld Surface Analysis

A new mixed ligand palladium(II) complex with bidentate NS‐donor chelate, [PdCl(PPh₃)L] (L: S‐allyl β‐N‐(benzylidene)dithiocarbazate), has been prepared and characterized using single crystal X‐ray diffraction and spectroscopic (electronic, IR, ¹H NMR and ¹³C NMR) techniques. The shorter Pd? P bond distance, 2.255(7) Å, than the sum of the single bond radii for palladium and phosphorus (2.41 Å), showed partial double bond character. Visualizing and exploring the crystal structure using Hirshfeld surface analysis showed the presence of π··· π, N··· π, C? H··· π, Cl···H and weak C? H···S interactions as most important intermolecular interactions in the crystal lattice, which are responsible to extension of the supramolecular network of the compound and stabilization of the crystal structure.     

One‐pot Synthesis of a 3,4,5‐Triaryltriazole from the Subsitituted 1,3,4‐Oxadiazole: Crystal Structures Characterization

Two heterocyclic compounds, 2‐(p‐bromophenyl)‐5‐(2‐pyridyl)‐1,3,4‐oxadiazole ( 1 ) and 3‐(p‐bromophenyl)‐4‐phenyl‐5‐(2‐pyridyl)‐1,2,4‐triazole ( 2 ) were successfully synthesized and characterized by UV–vis, FTIR, ¹H NMR, ESI‐MS spectra, elemental analysis, and single crystal X‐ray crystallography. The structural analysis indicates that 1 is almost a planar molecule but 2 not. The crystal structure of 1 is stabilized by two kinds of intermolecular π–π interactions and two types of intermolecular C–H···N hydrogen bonds, whereas 2 by three kinds of C–H···π interactions and three types of intermolecular C–H···N hydrogen bonds. Additional, 2 can be prepared directly from 1 in an aniline solution at 190°C in a yield of 70%.     

Molecular Adducts of Isoniazid: Crystal Structure,Electronic Properties,and Hirshfeld Surface Analysis

Three molecular adducts of the antituberculosis drug isoniazid (INH) are synthesized with γ-resorcylic acid (γRA), phloroglucinol (PG), and gallic acid (GA). The new solid phases are preliminarily characterized by the thermal analysis (DSC/TGA) and powder X-ray diffraction. The formation of new solid phases is confirmed by single crystal X-ray diffraction, infrared (FT-IR) and Raman spectroscopy. All three new solid crystalline forms are stabilized by various hydrogen bonding interactions such as N⁺···H–O^–, N···H–O, O···H–O, and π–π stacking. The FT-IR analysis puts forward that the solid form of INH1 is a salt whereas the INH2 and INH3 molecular complexes are cocrystals. We have also investigated the density of states (DOS), band structure, and atomic orbit projected density of state (PDOS) of title compounds by adopting the density functional theory (DFT) technique in the local density approximation (LDA). The electronic structure calculations show that energy states are delocalized in the k-space due the hydrogen and covalent bonds in the crystals. The frontier molecular orbital (FMO) analysis reveals that charge transfer takes place within the compounds. The Hirshfeld analysis shows that H–H and N?H–O hydrogen bonding interactions are dominant in all three molecular adducts of INH.     

Different molecular assemblies in two new phosphoric triamides with the same C(O)NHP(O)(NH)<Subscript>2</Subscript> skeleton: crystallographic study and Hirshfeld surface analysis

Different molecular assemblies were compared in two new structures [4-CH₃-C₆H₄C(O)NH]P(O)[NH]₂(CH₂)₃, 1, and [4-CH₃-C₆H₄C(O)NH]P(O)[NHC₆H₃(3,4-CH₃)₂]₂, 2, belonging to the families of “cyclic phosphoric triamide” and “phosphoric triamide”, respectively. The differences in the hydrogen bond motifs were discussed (by single crystal X-ray diffraction) as a result of three factors: (1) action of two N atoms with a non-planar environment in 1 as an H-bond acceptor, (2) different orientations of three N–H bond vectors in two molecules and (3) different conformations of C=O and P=O groups. These differences lead to more complicated hydrogen bond pattern of 1, with respect to that of 2, as structure 1 may be considered as a model of four-acceptor–three-donor versus a two-acceptor–three-donor system in 2. The main discrepancies of 1 and 2, monitored by the Hirshfeld surface analysis, are related to the contribution portions of O···H/H···O contacts, in which compound 1 not only involves the greater existence of classical hydrogen bonds but also contains the further C–H···O weak interactions in its crystal packing with respect to compound 2. Instead, in 2, the shortage of O···H/H···O contacts has been partially compensated by the C···H/H···C interactions, due to the presence of more unsaturated carbon acceptors. The differences in assemblies are also reflected in the solid-state IR spectra, especially for the N–H vibration frequencies. The new compounds were further studied by 1D NMR experiments (¹H, ¹³C, ³¹P), 2D NMR techniques [HMQC and HMBC (H–C correlation), HSQC (N–H correlation)], high-resolution ESI–MS, EI–MS spectrometry and IR spectroscopy.     

Elaboration,Structural, Vibrational,DSC Investigations and Hirshfeld Surface Analysis of New Organic–Inorganic Hybrid Compound: [H<Subscript>2</Subscript>mela]Cu<Subscript>2</Subscript>Br<Subscript>6</Subscript>

The present paper accounts for the synthesis, crystal structure, differential scanning calorimetry and vibrational spectroscopy of a new compound (1,3,5-triazinidium-2,4,6-triamine) hexabromidodicuprate (II) grown at room temperature by slow evaporation of aqueous solution. From X-ray diffraction data collected at room temperature, it is concluded that it crystallizes in the monoclinic system (P2₁/c space group). The anion and the cation are linked by N–H···Br hydrogen bonds. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed. The differential scanning calorimetric has also been investigated. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.     

Synthesis,Structure and Properties of a Novel Tetranuclear Copper Cluster-Based Polymer with Di-Schiff-Base

A novel tetranuclear cluster-based polymer {[Cu₄(L)₂(NO₃)₂(DMF)₂]·(CH₂Cl₂)₂}_n (1, H₃L = (1Z,2E,N′E)-N′,2-bis(2-hydroxybenzylidene)hydrazinecarbohydrazonic acid) was synthesized through diffusion method. The structure of 1 was characterized by elemental analysis, IR, and single crystal X-ray diffraction. 1 is tetranuclear copper cluster which further constructed 1-D chain through double Cu–O bonds. Luminescent and magnetic properties of 1 have been studied. Hirshfeld surfaces analysis revealed that complex 1 was supported mainly by H···H, O···H and H···Cl intermolecular interactions.     

Synthesis and Crystal Structure of a [Mo8O26]4– Cluster Derivative with 4‐MePyH+. First β‐Octamolybdate Derivative with π–π Stacking

Dioxobis(pyridine‐2‐thiolate‐N, S)molybdenum(VI) (MoO₂(Py‐S)₂), reacts with of 4‐methylpyridine (4‐MePy) in acetonitrile, by slow diffusion, to afford the title compound. This has been characterized by elemental analysis, IR and ¹H NMR spectroscopy. The X‐ray single crystal structure of the complex is described. Structural studies reveal that the molecular structure consists of a β‐Mo₈O₂₆ polyanion with eight MoO₆ distorted edge‐shared octahedra with short terminal Mo–O bonds (1.692–1.714 Å), bonds of intermediate length (1.887–1.999 Å) and long bonds (2.150–2.473 Å). Two different types of hydrogen bonds have been found: N–H···O (2.800–3.075 Å) and C–H···O (3.095–3.316 Å). The presence of π–π stacking interactions and strong hydrogen bonds are presumably responsible for the special disposition of the pyridinic rings around the polyanion cluster.     

On the relationships between molecular conformations and intermolecular contacts toward crystal self-assembly of mono-, di-, tri-, and tetra-oxygenated xanthone derivatives

Oxygenated xanthones have been extensively investigated over the years, but there are few reports concerning their crystal structure. Our chemical investigations of Brazilian plants resulted in the isolation of four natural products named 1-hydroxyxanthone (I), 1-hydroxy-7-methoxyxanthone (II), 1,5-dihydroxy-3-methoxyxanthone (III), and 1,7-dihydroxy-3,8-dimethoxyxanthone (IV). The structures of these compounds were established on the basis of single crystal X-ray diffraction. The xanthone nucleus conformation is essentially planar with the substituents adopting the orientations less sterically hindered. In addition, classical intermolecular hydrogen bonds (O–H···O) present in III and IV give rise to infinite ribbons. However, the xanthone I does not present any intermolecular hydrogen bonds, meanwhile the xanthone II presents only a non-classical one (C–H···O). The crystal packing of all xanthone structures is also stabilized by π–π interactions. The fingerprint plots, derived from the Hirshfeld surfaces, exhibited significant features of each crystal structures.     

Synthesis, Characterization and Crystal Structure of [Na2(APZC)2(μ-H2O)2(μ3-H2O)]n

The synthesis and spectroscopic properties of a Na^＋ complex with ligand 3-aminopyrazine-2-carboxylic acid were described. The resulting complex was characterized by elemental analysis, IR, UV-Vis, NMR spectroscopy and single crystal X-ray diffraction method. The title compound crystallizes in the triclinic system with space group . The crystalline structure of this compound consists of supramolecular architectures involving strong intramolecular N—H…O in pyrazine molecules and intermolecular O—H…N, O—H…O, and N—H…N hydrogen bonds between substituted pyrazine and water molecules.     

Synthesis,characterization, X-ray diffraction studies and biological evaluation of tert-butyl 4-(2-ethoxy-2-oxoethyl)-piperazine-1-carboxylate and tert-butyl 4-(2-hydrazino-2-oxoethyl)piperazine-1-carboxylate

Two derivatives of N-Boc piperazine, an ester derivative, i.e., tert-butyl 4-(2-ethoxy-2-oxoethyl)-piperazine-1-carboxylate (1), and, a hydrazide derivative tert-butyl 4-(2-hydrazino-2-oxoethyl)piperazine-1-carboxylate (2) were synthesized and were characterized by FT-IR, ¹H & ¹³C NMR and LCMS spectroscopic studies. The structures of both 1 and 2 were further confirmed by single crystal X-ray diffraction analysis. The molecule of 1 is linear in shape with the ethyl acetate moiety adopting fully extended conformation, while the molecule of 2 is L-shaped with the molecule being twisted at the C10 atom. The crystal structure of 1 adopts a two-dimensional zig-zag architecture featuring C–H…O intermolecular interactions, while that of 2 features strong N–H…O hydrogen bonds and intermolecular interactions of the type N–H…N and C–H…N, resulting in a two-dimensional structure. Furthermore, a detailed analysis of the intermolecular interactions and crystal packing of 1 and 2 via Hirshfeld surface analysis and fingerprint plots was performed. The antibacterial and antifungal activities of both the compounds have been studied against several microorganisms, and were found to be moderately active.     

2,4‐Dimethyl‐1,3‐thiazole‐5‐carboxylic acid: an X‐ray structural study at 100 K and Hirshfeld surface analysis

The crystal structure of the title thiazolecarboxylic acid derivative, C₆H₇NO₂S, (I), has been determined from single‐crystal X‐ray analysis at 100 K. In the crystal packing, an interplay of O—H...N and C—H...O hydrogen bonds connects the molecules to form C(6)R₂²(8) polymeric chains, which are further linked via weak C—H...O hydrogen bonds into a two‐dimensional supramolecular framework. The relative contributions of different interactions to the Hirshfeld surface in (I) and a few related thiazolecarboxylic acid derivatives indicate that the H...H, N...H and O...H contacts can account for about 50–70% of the total Hirshfeld surface area in this class of compound.     

Synthesis,crystal structure,Hirshfeld surface analysis and DNA binding properties of interactions with lattice pyrazinamide and its zinc(II) coordination polymer

The compound {[Zn(μ_1,5-dicyanamide)₂(pyrazinamide)₂](pyrazinamide)₂}_n has been synthesized and further characterized by elemental analysis, single-crystal X-ray diffraction, and thermogravimetric analysis. Structural analysis revealed that the dicyanamide anion acted as bridging ligand in a μ-1,5 mode, resulting a polymeric 1-D chain structure. The pairwise N3-H3B···N1 and N9-H9B···N7, N3-H3A···O2 and N9-H9A···O1, N3-H3B···N7 and N9-H9B···N1 multiple hydrogen bonding interactions, impart enhanced stability to supramolecular structures. Hirshfeld surfaces and fingerprint plots were applied to arrive at the same conclusion, which is stabilised mainly by H–H, N–H, O–H interactions. DNA binding studies showed that the compound had interacted with DNA.     

Intermolecular interactions in group 14 hydrides: Beyond CH···HC contacts

In line with previous work in which we established the factors that enhance attractive C?H···H?C dihydrogen interactions in alkanes, an extended theoretical analysis of noncovalent intermolecular interactions in group 14 hydrides is presented here. Remarkably, these weak interactions may play a major role in determining the crystal structures adopted by several families of molecules. A combined structural and computational analysis at the MP2 level allowed us to identify and characterize different interactions of the type E?H···H?E and E···H?E (E = Si, Ge, Sn, and Pb), and to find also the most suitable scenario for the establishment of each particular type. The nature of the interactions has been analyzed in terms of natural charges of the atoms involved and a topological analysis of the electron density of several dimers confirms the existence of H···H and H···E attractive contacts. We have observed that the interaction strength increases when descending down the periodic group and that silicon has a marked tendency to establish Si···H?Si interactions. A size‐dependent backbone effect that reinforces H···H dihydrogen interactions in polyhedral systems has also been found.     

Intermolecular interactions in group 14 hydrides: Beyond C?H···H?C contacts

In line with previous work in which we established the factors that enhance attractive C? H···H? C dihydrogen interactions in alkanes, an extended theoretical analysis of noncovalent intermolecular interactions in group 14 hydrides is presented here. Remarkably, these weak interactions may play a major role in determining the crystal structures adopted by several families of molecules. A combined structural and computational analysis at the MP2 level allowed us to identify and characterize different interactions of the type E? H···H? E and E···H? E (E = Si, Ge, Sn, and Pb), and to find also the most suitable scenario for the establishment of each particular type. The nature of the interactions has been analyzed in terms of natural charges of the atoms involved and a topological analysis of the electron density of several dimers confirms the existence of H···H and H···E attractive contacts. We have observed that the interaction strength increases when descending down the periodic group and that silicon has a marked tendency to establish Si···H? Si interactions. A size‐dependent backbone effect that reinforces H···H dihydrogen interactions in polyhedral systems has also been found.