Crystal Packing Of Compounds Research Articles

Phenylenethynylene derivatives of [2.2]paracyclophane: A relationship between crystal structure and fluorescent properties in a solid state

Isomeric di- and tetrasubstituted derivatives of [2.2]paracyclophane containing 1,4-bis(phenylethynyl)benzene as a main component were synthesized. It was found that when shifting from 1,4-bis(phenylethynyl)benzene, 1, to pseudo-para-disubstituted 4,16-di-{phenylethynyl(1,4-phenylene)ethynyl}[2.2]paracyclophane, 2, and then to tetrasubstituted 4,7,12,15-tetra-phenylethynyl[2.2]paracyclophane, 3, the difference between fluorescence maxima in solid state and in solution decreases. Analysis of crystal structure using Hirschfeld method revealed that observed phenomenon correlates well with proportion of C-C contacts in crystal packing of compounds. It has been found, that for [2.2]paracyclophane derivatives 2 and 3, the main contribution to this effect is due to π–π contacts of the proximal paracyclophane groups of neighboring molecules, rather than to stacking interactions discovered for 1. The different polymorphic forms of compound 1 that are present both in film and in solid state are discussed.

Hydrogen bonding, halogen bonding and C–H…π interactions governing the supramolecular architecture of 1-(4-(4-bromophenyl)piperazin-1-yl)-2-chloroethan-1-one: Insights from X-ray crystallography, DFT calculations and urease inhibitory assessment

The use of organic ligands for the generation of supramolecular architectures exhibiting interesting structural properties in crystal engineering have garnered significant attention. In this context, the current work highlights the use of 1-(4-(4-bromophenyl)piperazin-1-yl)-2-chloroethan-1-one (3) as a valuable synthon for evaluating the conspicuous role of several types of noncovalent interactions governing the formation of supramolecular assemblies. Compound 3 was successfully synthesized in good yield using a facile two-step approach and characterized through spectroscopic and X-ray crystallographic methods. Noncovalent interactions including C—H…O, C—H…Cl, C—H…π as well as C—Br…Cl halogen bonds were found as the key contacts in the crystal packing of compound 3. DFT calculations were employed to identify and assess the impact of the C—Br…Cl halogen bond, utilizing MEP, QTAIM, and NBO analyses. These studies confirmed that the Br atom acts as the halogen bond donor and the Cl atom as the halogen bond acceptor. Assessment of urease inhibitory efficacy revealed that the tested compound exhibits a 16-folds superior inhibition than thiourea. Computational modeling analysis augmented the in vitro results by exhibiting numerous favorable binding interactions between compound 3 and active site residues such as TYR32, LYS709, PHE712, ASP730, VAL744 and MET746. The pharmacokinetic evaluation classified the investigated piperazine derivative into a druggable compound.

Never-Ending Story: New Cyclodextrin-Based Metal-Organic Framework Crystal Structures Obtained Using Different Crystallization Methods.

Six novel cyclodextrin (CD)-based metal-organic frameworks (MOFs) were synthesized using distinct crystallization methodologies. A modified vapor diffusion method is introduced for the first time, termed fast crystallization, which enables the rapid solid-state formation of MOF compounds. This innovative method yielded four of the newly synthesized MOFs. The crystal structures of five obtained frameworks were structurally characterized through single-crystal X-ray diffraction, while one, compound 5 (γ-CD-K-5), was additionally characterized as a bulk powder. Structural analysis revealed that two of the newly obtained MOFs, namely, compound 2 (α-CD-K-2) and compound 3 (α-CD-Rb-3), exhibited isostructural characteristics, forming a three-dimensional (3D) framework. Compound 1 (α-CD-K-1) shared the same space group as EVEGET (α-CD-K) and displayed the same framework type. Furthermore, the crystal packing of compound 4 (β-CD-K-4) closely resembled that of compound 1 and EVEGET, with the only distinction lying in the type of CD employed. Notably, compound 6 (γ-CD-K-6) incorporated an iodine ion with an occupancy of 0.2. To discern the intermolecular interactions within the obtained MOFs, the Hirshfeld surface was calculated using Crystal Explorer software.

Topological control through the solvent effect in two-dimensional cadmium coordination polymers

Two new solvent-induced cadmium (II) coordination polymers, {[CdL1.5(NO3)2](CH3CN)}n (1) and [CdL(NO3)2(H2O)]n (2) were successfully synthesized from the same initial materials Cd(NO3)2.4H2O and 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (L) in EtOH/CH3CN and CH3CN solvent systems, respectively. These coordination polymers were structurally characterized by single-crystal X-ray diffraction analysis and further identified by infrared spectra (FTIR) and powder X-ray diffraction (PXRD). The influence of the solvent system can be observed by a significant change in the topological features. As controlled by solvent, compound 1 shows a 2D coordination polymer that can be simplified as a (6,3) net, while compound 2 is two-dimensional (4,4) coordination network. Our results provide interesting insights into solvent effects on the topological control in construction of non-interpenetrated coordination polymers. Hirshfeld surface analysis of the structures 1 and 2 is used to investigate the percentage of participation of intermolecular interactions in the crystal packing of compounds 1 and 2.

C–H…X (X = F, Cl, Br, I) Versus π-Stacking in the Crystal Packing of Compounds Containing the {M(tpy)X3} Motif

Analysis of the data in the Cambridge Structural Database (CSD) for compounds containing an {M(tpy)X3} motif (tpy = 2,2’:6’,2”-terpyridine, M = any metal, X = F, Cl, Br, I) reveals 17 isostructural mononuclear [M(tpy)X3] compounds crystallizing without lattice solvent; both face-to-face π-stacking of pyridine rings and C–H3/H3’…X hydrogen bonding appear to be equally important. Regardless of coordination number (CN = 6, 7 or 8) and nuclearity (mono- or dinuclear), a recurring packing feature in other compounds containing an {M(tpy)X3} unit is the presence of bifurcated Cl…H3/H3’ interactions, complemented in some cases by Cl…H5’/H3” interactions, consistent with the acidic H3, H3’, H5’, and H3” atoms of a coordinated tpy ligand. Octahedral [M(tpy)F3] complexes crystallize as hydrates with strong F…H–OH hydrogen bonding dominating the crystal packing.

Synthesis of <I>N</I>'-(2,3-dihydroxybenzylidene)-4-methylbenzohydrazide: Spectroscopic Characterization and X-ray Structure Determination

p-Toluic hydrazide was used for synthetizing a new Schiff base <I>N</I>'-(2,3-dihydroxybenzylidene)-4-methylbenzohydrazide (I). The prepared compound was characterized by elemental analysis, infrared and ¹H and ¹³C NMR spectroscopy techniques, and the structure of compound (I) was determined by single-crystal X-ray diffraction study. The compound (C₁₅H₁₄N₂O₃) crystallises in the monoclinic space group <I>P</I>2₁/<i>n</i> with the following unit cell parameters: <i>a</i> = 11.7820 (6) Å, <i>b</i> = 8.5278 (4) Å, <i>c</i> = 13.6054 (7) Å, <i>β</i> = 109.346 (5)°, <I>V </I>= 1289.81 (12) ų, <I>Z</I> = 4, <I>R</I>₁ = 0.071 and <i>wR</i>₂ = 0.197. The X-ray structure shows that the compound (I) adopts an <I>E</I> configuration with respect to the double bond C7=N1. The carbonyl oxygen atom O3 and the nitrogen atom N1 of the hydrazide moiety are in a <i>syn</i> conformation with respect to C8—N2 bond. The crystal packing of compound (I) is stabilized by intramolecular O(phenol)–H•••N(carbohydrazide) which results in an <I>S</I>(6) ring motif and intermolecular O(phenol)–H•••O(carbohydrazide) hydrogen bonds which form chains. The carbonohydrazide moiety C=N–N–C(O)–N–N=C fragment is almost coplanar with the two benzene rings with dihedral angles of their mean planes of 10.35° [C1—C6] and 7.99° [C9—C14], respectively. The dihedral angle between the mean planes of the phenyl rings is 2.46°.

Synthesis, crystal structure analysis, DFT calculations, antioxidant and antimicrobial activity of N,N-di-2,4-dimethoxybenzyl-N'-2-nitrobenzoylthiourea

N,N-Di-2,4-dimethoxybenzyl-N'-2-nitrobenzoylthiourea (MBNBT) was synthesized and characterized by 1D and 2D NMR spectroscopy. The molecular structure of MBNBT was also confirmed by SCXRD study. The molecular structure of MBNBT was optimized using the theory level of B3LYP/6–311G(d,p). The obtained theoretical results were compared with experimental ones. Molecular parameters such as bond lengths and bond angles were compared with SCXRD data. Molecular characteristics such as the HOMO-LUMO energy, the energy gap between the LUMO and HOMO energies, and surface maps of molecular electrostatic potential were investigated. Hirshfeld surface analysis showed that H···H (42.5%), H···O/O···H (25.5%), H···C/C···H (17.6%), H···S/S···H (7.1%), and C···O/O···C (2.7%) interactions contact is the most significant contributors in crystal packing of compound. The visualization of 3D topology of molecular packing of the crystal packing for MBNBT is elucidated from energy-framework calculations which suggest that the intermolecular contacts formed between participating molecules are principally dispersive in nature. Furthermore, the antimicrobial and antioxidant activity properties of MBNBT were investigated. The in vitro antioxidant activity of MBNBT was tested by DPPH free radical scavenging activity, H2O2 scavenging activity, superoxide radical scavenging activity and ferric reducing antioxidant power methods. According to the results obtained from the experimental studies, it was determined that MBNBT has effective antioxidant and free radical scavenging activity, when compared with reference substances. At the same time, as a result of antimicrobial activity studies, it was determined that it was effective against C. parapsilosis and C. metapsilosis.

Intramolecular resonance assisted N–H⋅⋅⋅O=C hydrogen bond and weak noncovalent interactions in two asymmetrically substituted geminal amido-esters: Crystal structures and quantum chemical exploration

Two asymmetrically substituted geminal amido-esters, namely ethyl (2E)-2-[(2,5-dimethoxy phenyl)carbamoyl]-3-[(4-nitrophenyl)amino] prop-2-enoate (I) and ethyl (2E)-2-[(9,10-dioxo-9,10-dihydroanthracen-1-yl)carbamoyl]-3-(phenylamino) prop-2-enoate (II) were synthesized and the nature and strength of intramolecular resonance assisted hydrogen bond (RAHB) and non-RAHB was studied. X-ray analysis revealed that intramolecular N–H⋅⋅⋅O, and C–H⋅⋅⋅O interactions lead to the formation of angularly fused pseudo tricyclic (A-C) motif in compound I and fused pseudo pentacyclic (A-E) motif in compound II. Intramolecular RAHB; non-RAHB interactions are characterized and quantified by Bader's quantum theory of atoms-in-molecules approach (QTAIM). In both compounds, ring A was found to exhibit intramolecular RAHB characteristics. Crystal structures of I and II are stabilized by weak intermolecular C–H⋅⋅⋅O, C–H⋅⋅⋅π, and π⋅⋅⋅π interactions. Intermolecular interaction energies for different molecular dimers in I and II have been quantified by using the PIXEL, QTAIM, and DFT methods. The pseudoring stacking interaction is observed only in compound II whereas no such stacking interactions are seen in compound I. Hirshfeld surface (HS) analysis suggested that the H⋅⋅⋅H and O⋅⋅⋅H contacts are the first and second dominant contacts in both crystal structures. The theoretical charge density analysis revealed that the C–H⋅⋅⋅O and C–H⋅⋅⋅C(π) interactions produce closed-shell characteristics. Further, the crystal packing of compounds I and II analyzed based on the energy frameworks.

SYNTHESIS OF (Z)-N'-(PHENYL(PYRIDIN-2-YL)METHYLENE)-NICOTINOHYDRAZIDE: STRUCTURAL CHARACTERIZATION AND ANTIOXIDANT ACTIVITY SCREENING

Asymmetrical ligand ( Z )- N '-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide ( I ) was synthesized from the condensation of nicotinic acid hydrazide with 2-benzoylpyridine. The compound was characterized by physicochemical analyses, elemental analysis, FTIR, 1 H and 13 C NMR spectroscopy techniques. The structure of the compound was determined by a single-crystal X-ray diffraction study. The ligand crystallizes in the triclinic space group P-1 with the following unit cell parameters: a = 8.2699 (11) A, b = 8.6514 (8) A, c = 11.583 (11) A, a = 91.308 (3)°, b = 94.155 (5)°, g = 109.008 (4)°, V = 755.17 (14) A 3 , Z = 2, R 1 = 0.050, wR 2 = 0.145. The carbonohydrazone moiety of the molecule is slightly twisted as reflected by the torsion angles values of -1.2 (2)° [O1—C13—N3—N2]. The dihedral angle between the mean planes of the pyridine rings is 11.799 (9)°. The crystal packing of compound ( I ) is stabilized by intramolecular N(carbohydrazide)–H···N(pyridine) and intermolecular C(phenyl)–H···O(amide) and C(phenyl)–H···N(hydrazino) hydrogen bonds, leading to the formation of sheets parallel to ac plane. The compound screened for antioxidant activity showed variable DPPH inhibition value for different concentrations of DPPH solution.

Synthesis of mono and bis-substituted asymmetrical compounds, (1-(pyridin-2-yl)ethylidene)carbonohydrazide and 1-(2'-hydroxybenzylidene)-5-(1'-pyridylethylidene)carbonohydrazone: Structural characterization and antioxidant activity study

Carbonohydrazide was used for synthetizing a new dissymmetrical bis-substituted Schiff base 1-(2'-hydroxybenzylidene)-5-(1'-pyridylethylidene)carbonohydrazone (2). A mono substituted compound (1-(pyridin-2-yl)ethylidene)carbonohydrazide (1) was firstly prepared by condensation reaction of carbonohydrazide and 2-acetylpyridine in 1:1 ratio. Secondly, compound 2 was obtained by condensation reaction of compound 1 and salicylaldehyde in 1:1 ratio. The prepared compounds were characterized by elemental analysis, infrared and 1H and 13C NMR spectroscopy techniques, and the structure of compound 2 was determined by single-crystal X-ray diffraction study. The compound 2 (C15H15N5O2) crystallises in the monoclinic space group P21/c with the following unit cell parameters: a = 8.3683(3) Å, b = 13.9986(4) Å, c = 12.1610(4) Å, β = 97.512(3)°, V = 1412.37(8) Å3, Z = 4, T = 100(2) K, μ(MoKα) = 0.098 mm-1, Dcalc = 1.398 g/cm3, 6057 reflections measured (5.708° ≤ 2Θ ≤ 54.962°), 6057 unique (Rsigma = 0.0395) which were used in all calculations. The final R1 was 0.0474 (I &gt; 2σ(I)) and wR2 was 0.1971 (all data). The oxygen atom O1 and the azomethine nitrogen atom N5 adopt cis-configuration relative to the C8-N4 bond, while O1 adopts trans-configuration with the azomethine nitrogen atom N2 relative to C8-N3 bond. The crystal packing of compound 2 is stabilized by intramolecular O(phenol)–H···N(carbohydrazide) and intermolecular N (carbohydrazide)–H···O (carbo-hydrazide) hydrogen bonds which form layers parallel to [010] axis. Additional C–H···O hydrogen bond consolidate the structure. The carbonohydrazide moiety C=N–N–C(O)–N–N=C fragment and the phenyl ring are almost coplanar; with an angle of 1.73(1)° between their means plans. The dihedral angle between the mean planes of the phenyl and the pyridine rings is 22.267(2)°.

Synthesis and crystal structures of 2-(ferrocenyl-carbon-yl)benzoic acid and 3-ferrocenylphthalide.

The title compounds, 2-(ferrocenylcarbon-yl)benzoic acid, [Fe(C5H5)(C13H9O3)], 1, and 3-ferrocenylphthalide [systematic name: 3-ferrocenyl-2-benzo-furan-1(3H)-one], [Fe(C5H5)(C13H9O2)], 2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The crystal structure of compound 1 was solved recently at room temperature [Qin, Y. (2019 ▸). CSD Communication (CCDC deposition number 1912662). CCDC, Cambridge, England]. Here we report a redetermination of its crystal structure at 90 K with improved precision by a factor of about three. The mol-ecular structures of both compounds exhibit a typical sandwich structure. In the crystal packing of compound 1, each mol-ecule engages in inter-molecular hydrogen bonding, forming a centrosymmetric dimer with graph-set notation R 2 2 (8) and an O⋯O distance of 2.6073 (15) Å. There are weak C-H⋯O and C-H⋯π inter-actions in the crystal packing of compound 2. The phthalide moiety in 2 is oriented roughly perpendicular to the ferrocene backbone, with a dihedral angle of 77.4 (2)°.

Twist-chair conformation of the tetraoxepane ring remains unchanged in tetraoxaspirododecane diamines.

A detailed structural analysis has been performed for N,N'-bis(4-chlorophenyl)-7,8,11,12-tetraoxaspiro[5.6]dodecane-9,10-diamine, C20H22Cl2N2O4, (I), N,N'-bis(2-fluorophenyl)-7,8,11,12-tetraoxaspiro[5.6]dodecane-9,10-diamine, C20H22F2N2O4, (II), and N,N'-bis(4-fluorophenyl)-7,8,11,12-tetraoxaspiro[5.6]dodecane-9,10-diamine, C20H22F2N2O4, (III). The seven-membered ring with two peroxide groups adopts a twist-chair conformation in all three compounds. The lengths of the C-N and O-O bonds are slightly shorter than the average statistical values found in the literature for azepanes and 1,2,4,5-tetraoxepanes. The geometry analysis of compounds (I)-(III), the topological analysis of the electron density at the (3,-1) bond critical points within Bader's quantum theory of `Atoms in molecules' (QTAIM) and NBO (natural bond orbital) analysis at the B3LYP/6-31G(d,2p) level of theory showed that there are nO→σ*(C-O), nN→σ*(C-O) and nO→σ*(C-N) stereoelectronic effects. The molecules of compounds (I) and (III) are packed in the crystals as zigzag chains due to strong N-H...O and C-H...O hydrogen-bond interactions, whereas the molecules of compound (II) form chains in the crystals bound by N-H...O, C-H...π and C-H...O contacts. All these data show that halogen atoms and their positions have a minimal effect on the geometric parameters, stereoelectronic effects and crystal packing of compounds (I)-(III), so that the twist-chair conformation of the tetraoxepane ring remains unchanged.

Electronic aspects of hydrogen bond patterns of P=O···H in crystal structures of phosphoramido acid derivatives: QSAR study of anti-urease activity, Hirshfeld surface analysis, and DFT calculations

New derivatives of phosphoramido acid with the formula(C6H11NCH3)(NHCOCF3)P(O)(O−)(CH3–+NH2–C6H11)(1) (amidophosphoricacid), (C6H5)2P(O)(O−)(+NH3–C6H4–NH2)(2) (phosphonicacid), (C6H5O)2P(O)(O−)(+NH3–C6H4–NH2) (3) (phosphoricacidester) were synthesized and characterized by X-ray crystallography. The asymmetric unit of compounds 1–3 consists of one molecule with the P atom in a tetrahedral environment. The X-ray structural analysis showed that the H-bond patterns depend on the kind of atoms linked to the P atom. In the crystal packing of compound 1, P(O)···H–N and C(O)···H–N hydrogen bonds in 3 and P(O)···H–N distances in compounds 2 and 3 led to a one-dimensional arrangement. The energy of P–O···H–N hydrogen bond (EHB) model and stabilizing energies (E2) were calculated. Hirshfeld surface analysis demonstrated that the C···H contact is attributed to CH···π contact in the 2 and 3 compounds and the F···H contact is referred to hydrogen bond in one O···H counterion interaction. Quantitative structure–activity relationship (QSAR) was used to comprehend the relationship between molecular structural features and the inhibitory of investigated compounds. The use of density functional theory along with the QSAR model for enzymes revealed the importance of QH parameter in describing the anti-AChE and anti-urease activities of monophosphoramidates including P(O)–NH2 moiety.

4-(2-Methoxyphenyl)-5-(thiophen-2-ylmethyl)-2,4-Dihydro-1H-1,2,4-Triazole-3-Thione and Its Complex with Cadmium Chloride: Molecular and Crystal Structures

Compound 4-(2-methoxyphenyl)-5-(thiophen-2-ylmethyl)-2,4-dihydro-1H-1,2,4-triazole-3-thione (LН) and its complex with cadmium(II) C42.12H39.50N9O3.12S6Cl2Cd (I) are synthesized. Their molecular and crystal structures are determined by X-ray diffraction analysis (СIF files CCDC nos. 1835776 (LН) and 1547251 (I)). Free ligand LН is thione and in the crystal forms H-bonded centrosymmetric dimers by two hydrogen bonds N–H···S. Complex I has a distorted trigonal bipyramidal structure: the sulfur atoms lie in the base and the chlorine atoms occupy the axial positions. Compound LН manifests itself as a monodentate ligand (S) when forming complex I and retains the thione form. The molecule of complex I is stabilized due to strong intramolecular contacts N–H···Cl. The crystal packing of compounds LН and I is formed due to the intermolecular contacts C–H···π, H···S, H···O, and H···N.

Structural correlation and computational quantum chemical explorations of two 1,2,3-triazolyl-methoxypyridine derivatives as CYP51 antifungal inhibitors

Structural correlation and computational quantum chemical optimization of two 1,2,3-triazolyl-methoxypyridine derivatives fused with a five-membered heterocyclic moiety, furan (I) or thiophene (II), were performed. Compounds I and II belong to the triclinic crystal classification with P-1 space group. The bond lengths and angles of the optimized crystal structures are in good agreement with the XRD experimental data. We confirmed the hydrogen bonding interactions that observed in crystal packing of compounds I and II using Hirshfeld surface and energy framework analysis. The DFT functional non-linear optical and thermochemistry parameters of the title compounds were calculated. The local reactivity domains of compounds I and II were recognized by the Fukui function parameter analysis. In silico molecular docking simulations were carried out to discover the lanosterol 14 α-demethylase (CYP51) enzyme inhibition against target protein (PDB ID: 1EA1). Antifungal activity of the title molecules was predicted by in vitro antifungal studies against three fungal strains using fungal drug fluconazole as a positive control. Compound I exhibited enhanced affinity with receptor 1EA1 and higher inhibition activity with fungal strains compared to compound II.

Molecular self-assembly in indole-based benzamide derivative: Crystal structure, Hirshfeld surfaces and antimicrobial activity

Two new compounds, 1H-indole-7-amine (1) and N-(1H-indol-7-yl)-2-methylbenzamide (2) were synthesized and structurally characterized by NMR and FT-IR spectroscopic techniques. The molecular structure of compound 2 was further elucidated by single-crystal X-ray diffraction technique. Moreover, the crystal packing of compound 2 is analyzed in terms of non-covalent N-H···O, C-H···π, and parallel displaced π···π interactions. Hirshfeld surface analysis and decomposed fingerprint plots of the compound 2 were performed to visualize the presence of strong hydrogen bond N-H···O and C-H···π stacking interactions. Hirshfeld surface analysis and decomposed fingerprint plots show that the structure of compound 2 is stabilized by H···H, N-H···O, C-H···π and π···π intermolecular interactions and these interactions contribute mostly to molecular self-assembly in the crystal. In addition, compound 2 was evaluated for both their in-vitro antibacterial and antifungal activity. The obtained results have been reported, explained and compared with fluconazole and ampicillin used as reference drugs.

1D helical cadmium coordination polymers containing hydrazide ligand: The role of solvent and molar ratio

Three new cadmium coordination polymers, [Cd(L)(NO3)2CH3OH]n, 1, {[Cd(L)2(NO3)]NO3}n, 2 and {[Cd(L)2(NO3)]NO3.H2O}n3, which L is nicotinohydrazide have been synthesized and characterized by spectroscopic methods as well as single crystal X-ray diffraction. Compounds 1–3 have been synthesized by changing solvent and metal-to-ligand ratio. X-ray crystallography showed that compounds 1–3 have different 1D helical structural motif. Semi-flexible nature of L ligand causes to syn-syn conformation which leading to form 1D helical chains coordination polymers. Compounds 2 and 3 were synthesized under the same reaction conditions with similar molar ratio, but using different solvent system. These compounds are pseudopolymorph which differs in the presence or absence of water molecule in their crystal packing. Hirshfeld surface analysis of the structures 1–3 have been performed and find the percent of participation of intermolecular interactions in the crystal packing of compounds.

Steric repulsion and supra-molecular assemblies via a two-dimensional plate by C-H⋯O hydrogen bonds in two closely related 2-(benzo-furan-2-yl)-2-oxoethyl benzoates.

2-(Benzo-furan-2-yl)-2-oxoethyl 2-chloro-benzoate, C17H11ClO4 (I), and 2-(benzo-furan-2-yl)-2-oxoethyl 2-meth-oxy-benzoate, C18H14O5 (II), were synthesized under mild conditions. Their chemical and mol-ecular structures were analyzed by spectroscopic and single-crystal X-ray diffraction studies, respectively. These compounds possess different ortho-substituted functional groups on their phenyl rings, thus experiencing extra steric repulsion force within their mol-ecules as the substituent changes from 2-chloro (I) to 2-meth-oxy (II). The crystal packing of compound (I) depends on weak inter-molecular hydrogen bonds and π-π inter-actions. Mol-ecules are related by inversion into centrosymmetric dimers via C-H⋯O hydrogen bonds, and further strengthened by π-π inter-actions between furan rings. Conversely, mol-ecules in compound (II) are linked into alternating dimeric chains propagating along the [101] direction, which develop into a two-dimensional plate through extensive inter-molecular hydrogen bonds. These plates are further stabilized by π-π and C-H⋯π inter-actions.

Structural Characterization of Chirality‐Organized Ferrocene–Dipeptide Conjugates that Contain Pyridine N‐Oxide Moieties

AbstractTwo ferrocene–dipeptide conjugates, Fc(l‐Ala−l‐Pro−PyO)2 (2) and Fc(l‐Ala−l‐Pro−PyO)1 (3), were synthesized by the introduction of an l‐Ala−l‐Pro dipeptide that contained a C‐terminal pyridine N‐oxide moiety into the ferrocene organometallic scaffold. Single‐crystal X‐ray structure determination of ferrocene–dipeptide conjugate 2, which was composed of two dipeptide chains, confirmed the formation of intramolecular antiparallel β‐sheet‐like hydrogen bonds between the CO (Ala) and NH (Ala of another chain) groups to induce a chirality‐organized structure in which the ferrocenoyl moiety adopted a P‐helical chirality. In the crystal packing of compound 2, the peptide chains adopted a right‐handed molecular arrangement through hydrogen‐bonding interactions. On the contrary, ferrocene–dipeptide conjugate 3, which was composed of only one dipeptide chain, self‐assembled into a tetramer structure through the formation of intermolecular hydrogen bonds and π–π interactions between pyridine N‐oxide moieties.

Synthesis, characterization, and crystal structure of mercury(II) complex containing new phosphine oxide salt

The reaction of new phosphonium-phosphine oxide salt [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]Br (1) with mercury(II) iodide in a methanolic solution yielded [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2[Hg2I5Br](2). These two compounds were fully characterized by elemental analysis, IR, 1H, 31P, and 13C NMR spectra. Crystal and molecular structure of 2 has been determined by means of X-ray diffraction. In mercury compound, the phosphine oxide salt is found as a counter ion letting the mercury(II) ion to bound halides to all four coordination sites and to give dimermercurate(II) ions as the structure-constructing species. The neighboring [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2+cations are joined together by intramolecular CH⋯O hydrogen bonds to give a 1-D chain structure along the crystallographic b-axis. The [Hg2I5Br]2−anions act as cross-linkers between neighbouring strands extending the supramolecular structure into 2D layers in (110) planes as well as balances the charge of the complex. The significant effects of CH⋯X (XO, Br and I) and π⋯π aromatic interactions play a major role in the crystal packing of compound 2.