Crystal structure and analytical profile of 1,2-diphenyl-2-pyrrolidin-1-ylethanone hydrochloride or `α-D2PV': a synthetic cathinone seized by law enforcement, along with its diluent sugar, myo-inositol

A confiscated package of street drugs was characterized by the usual mass spectral (MS) and FT-IR analyses. The confiscated powder material was highly crystalline and was found to consist of two very different species, accidentally of sizes convenient for X-ray diffraction. Thus, one each was selected and redundant complete sets of data were collected at 100 K using Cu Kα radiation. The selected crystals contained: (a) 1,2-diphenyl-2-(pyrrolidin-1-yl)ethanone hydrochloride hemihydrate or 1-(2-oxo-1,2-diphenylethyl)pyrrolidin-1-ium chloride hemihydrate, C18H20NO+·Cl-·0.5H2O, (I), a synthetic cathinone called `α-D2PV', and (b) the sugar myo-inositol, C6H12O6, (II), probably the only instance in which the drug and its diluent have been fully characterized from a single confiscated sample. Moreover, the structural details of both are rather attractive showing: (i) interesting hydrogen bonding observed in pairwise interactions by the drug molecules, mediated by the chloride counter-anions and the waters of crystallization, and (ii) π-π interactions in the case of the phenyl rings of the drug which are of two different types, namely, π-π stacking and edge-to-π. Finally, the inositol crystallizes with Z' = 2 and the resulting diastereoisomers were examined by overlay techniques.

Preparation and Unique Three-Dimensional Self-Assembly Property of Starfish Ferritin

The structure and assembly properties of ferritin derived from aquatic products remain to be explored. Constructing diverse three-dimensional (3D) protein architectures with the same building blocks has important implications for nutrient delivery, medicine and materials science. Herein, ferritin from Asterias forbesii (AfFer) was prepared, and its crystal structure was resolved at 1.91 Å for the first time. Notably, different from the crystal structure of other reported ferritin, AfFer exhibited a BCT lattice arrangement in its crystals. Bioinspired by the crystal structure of AfFer, we described an effective approach for manufacturing 3D porous, crystalline nanoarchitectures by redesigning the shared protein interface involved in different 3D protein arrays. Based on this strategy, two 3D superlattices of body-centered tetragonal and simple cubicwere constructed with ferritin molecules as the building blocks. This study provided a potentially generalizable strategy for constructing different 3D protein-based crystalline biomaterials with the same building blocks.

Structural Characterization of Multicomponent Crystals Formed from Diclofenac and Acridines

Multicomponent crystals containing diclofenac and acridine (1) and diclofenac and 6,9-diamino-2-ethoxyacridine (2) were synthesized and structurally characterized. The single-crystal XRD measurements showed that compound 1 crystallizes in the triclinic P-1 space group as a salt cocrystal with one acridinium cation, one diclofenac anion, and one diclofenac molecule in the asymmetric unit, whereas compound 2 crystallizes in the triclinic P-1 space group as an ethanol solvate monohydrate salt with one 6,9-diamino-2-ethoxyacridinium cation, one diclofenac anion, one ethanol molecule, and one water molecule in the asymmetric unit. In the crystals of the title compounds, diclofenac and acridines ions and solvent molecules interact via N–H⋯O, O–H⋯O, and C–H⋯O hydrogen bonds, as well as C–H⋯π and π–π interactions, and form heterotetramer bis[⋯cation⋯anion⋯] (1) or heterohexamer bis[⋯cation⋯ethanol⋯anion⋯] (2). Moreover, in the crystal of compound 1, acridine cations and diclofenac anions interact via N–H⋯O hydrogen bond, C–H⋯π and π–π interactions to produce blocks, while diclofenac molecules interact via C–Cl⋯π interactions to form columns. In the crystal of compound 2, the ethacridine cations interact via C–H⋯π and π–π interactions building blocks, while diclofenac anions interact via π–π interactions to form columns.

Structure of Phycobilisomes

Phycobilisomes (PBSs) are extremely large chromophore-protein complexes on the stromal side of the thylakoid membrane in cyanobacteria and red algae. The main function of PBSs is light harvesting, and they serve as antennas and transfer the absorbed energy to the reaction centers of two photosynthetic systems (photosystems I and II). PBSs are composed of phycobiliproteins and linker proteins. How phycobiliproteins and linkers are organized in PBSs and how light energy is efficiently harvested and transferred in PBSs are the fundamental questions in the study of photosynthesis. In this review, the structures of the red algae Griffithsia pacifica and Porphyridium purpureum are discussed in detail, along with the functions of linker proteins in phycobiliprotein assembly and in fine-tuning the energy state of chromophores.

N-Heterocycles Scaffolds as Quorum Sensing Inhibitors. Design, Synthesis, Biological and Docking Studies

Quorum sensing is a communication system among bacteria to sense the proper time to express their virulence factors. Quorum sensing inhibition is a therapeutic strategy to block bacterial mechanisms of virulence. The aim of this study was to synthesize and evaluate new bioisosteres of N-acyl homoserine lactones as Quorum sensing inhibitors in Chromobacterium violaceum CV026 by quantifying the specific production of violacein. Five series of compounds with different heterocyclic scaffolds were synthesized in good yields: thiazoles, 16a-c, thiazolines 17a-c, benzimidazoles 18a-c, pyridines 19a-c and imidazolines 32a-c. All 15 compounds showed activity as Quorum sensing inhibitors except 16a. Compounds 16b, 17a-c, 18a, 18c, 19c and 32b exhibited activity at concentrations of 10 µM and 100 µM, highlighting the activity of benzimidazole 18a (IC50 = 36.67 µM) and 32b (IC50 = 85.03 µM). Pyridine 19c displayed the best quorum sensing inhibition activity (IC50 = 9.66 µM). Molecular docking simulations were conducted for all test compounds on the Chromobacterium violaceum CviR protein to gain insight into the process of quorum sensing inhibition. The in-silico data reveal that all 15 the compounds have higher affinity for the protein than the native AHL ligand (1). A strong correlation was found between the theoretical and experimental results.

Three AgI, CuI and CdII coordination polymers based on the new asymmetrical ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole: syntheses, characterization and emission properties

The new asymmetrical organic ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole (L, C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena-poly[[silver(I)-μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole] hexafluoridophosphate], {[Ag(L)]PF₆}_n, catena-poly[[copper(I)-di-μ-iodido-copper(I)-bis(μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)] 1,4-dioxane monosolvate], {[Cu₂I₂(L)₂]·C₄H₈O₂}_n, and catena-poly[[[dinitratocopper(II)]-bis(μ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)]-methanol-water (1/1/0.65)], {[Cd(L)₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one-dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π-π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.

Stimuli-responsive aggregation-induced fluorescence in a series of biphenyl-based Knoevenagel products: effects of substituent active methylene groups on π-π interactions

A series of three biphenyl-based Knoevenagel products (denoted 1a, 1b, 1c) with active methylene groups has been synthesized. Compounds 1a and 1b show strong solid-state fluorescence, whereas 1c displays low emission. Effects of substituent groups in condensed phase packing of the molecules have been investigated and correlated with their photophysical properties. Interestingly, compound 1a exhibits mechanofluorochromism with emission color changes from yellow to green (wavelength shift of 40 nm) after mechanical grinding. Furthermore, fluorescence of 1a and 1b is turned off under alkaline conditions, making them potential candidates for aggregation-enhanced emission-based pH sensors.

One-dimensional networks formed via the self-assembly of anthracenedibenzoic acid with zinc(II)

Self-assembly of metal-organic coordination polymers occurs because of enthalpically favorable interactions. In the case of the bulky 4,4'-(anthracene-9,10-diyl)dibenzoic acid ligand (abdH₂), we demonstrate that the presence of numerous π-π and C-H...π interactions outweigh the formation of saturated coordination complexes with zinc, leading to the formation of a dimethylformamide (DMF) solvate, namely 4,4'-(anthracene-9,10-diyl)dibenzoic acid dimethylformamide disolvate, C₂₈H₁₈O₄·2C₃H₇NO or [(abdH₂)(DMF)₂], at low concentrations of zinc. Meanwhile, at higher zinc concentrations, the abdH₂ ligand gives rise to the nonporous one-dimensional coordination polymer catena-poly[[bis(dimethylformamide-κO)zinc(II)]-μ-4,4'-(anthracene-9,10-diyl)dibenzoato-κ²O:O'], [Zn(C₂₈H₁₆O₄)(C₃H₇NO)₂]_n or [Zn(abd)(DMF)₂]_n, when assembled in dimethylformamide, while a related compound is observed when N,N-dimethylacetamide (DMA) is used as the solvent, namely catena-poly[[[bis(N,N-dimethylacetamide-κO)zinc(II)]-μ-4,4'-(anthracene-9,10-diyl)dibenzoato-κ²O:O'] N,N-dimethylacetamide monosolvate], {[Zn(C₂₈H₁₆O₄)(C₄H₉NO)₂]·C₄H₉NO}_n or {[Zn(abd)(DMA)₂]·DMA}_n. Attempts to use other amide-based solvents did not give rise to any other assembled structures.

π-π-Induced aggregation and single-crystal fluorescence anisotropy of 5,6,10b-tri-aza-acephenanthrylene

The structural origin of absorption and fluorescence anisotropy of the single crystal of the π-conjugated heterocyclic system 5,6,10b-tri-aza-acephenan-thrylene, TAAP, is presented in this study. X-ray analysis shows that the crystal framework in the space group P [Formula: see text] is formed by centrosymmetric dimers of face-to-face mutually oriented TAAP molecules joined by π-π non-covalent interactions. The conformation of the TAAP molecule is stabilized by intramolecular C-H⋯N(sp2), N(sp2)H⋯π(CN), and C-H⋯O(sp2) hydrogen bonds. The presence of weak π-π interactions is confirmed by quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. The analysis of the optical spectra of TAAP in solution and in the solid state does not allow the specification of the aggregation type. DFT calculations for the dimer in the gas phase indicate that the lowest singlet excitation is forbidden by symmetry, suggesting H-type aggregation, even though the overall absorption spectrum is bathochromically shifted as for the J-type. The experimental determination of the permanent dipole moment of a TAAP molecule in 1,4-dioxane solution indicates the presence of the monomer form. The calculated absorption and emission spectra of the crystal in a simple approximation are consistent with the experimentally determined orientation of the absorption and emission transition dipole moments in TAAP single crystals. The electrostatic interaction between monomers with a permanent dipole moment (ca 4 D each) could result in the unusual spectroscopic JH-aggregate behaviour of the TAAP dimer.

Atomistic Molecular Dynamics Simulations of the Initial Crystallization Stage in an SWCNT-Polyetherimide Nanocomposite

Crystallization of all-aromatic heterocyclic polymers typically results in an improvement of their thermo-mechanical properties. Nucleation agents may be used to promote crystallization, and it is well known that the incorporation of nanoparticles, and in particular carbon-based nanofillers, may induce or accelerate crystallization through nucleation. The present study addresses the structural properties of polyetherimide-based nanocomposites and the initial stages of polyetherimide crystallization as a result of single-walled carbon nanotube (SWCNT) incorporation. We selected two amorphous thermoplastic polyetherimides ODPA-P3 and aBPDA-P3 based on 3,3′,4,4′-oxydiphthalic dianhydride (ODPA), 2,3′,3,4′-biphenyltetracarboxylic dianhydride (aBPDA) and diamine 1,4-bis[4-(4-aminophenoxy)phenoxy]benzene (P3) and simulated the onset of crystallization in the presence of SWCNTs using atomistic molecular dynamics. For ODPA-P3, we found that the planar phthalimide and phenylene moieties show pronounced ordering near the CNT (carbon nanotube) surface, which can be regarded as the initial stage of crystallization. We will discuss two possible mechanisms for ODPA-P3 crystallization in the presence of SWCNTs: the spatial confinement caused by the CNTs and π–π interactions at the CNT-polymer matrix interface. Based on our simulation results, we propose that ODPA-P3 crystallization is most likely initiated by favorable π–π interactions between the carbon nanofiller surface and the planar ODPA-P3 phthalimide and phenylene moieties.

CuII and ZnII β-diketonate coordination polymers based on pyrimidin-2-amine, pyrazine and 1,2-bis(4-pyridyl)ethane

Copper(II) and zinc(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionato) compounds with pyrimidin-2-amine (pyr2a), pyrazine (pyz) and 1,2-bis(4-pyridyl)ethane (dpet) were prepared and solid-state structures of coordination polymers [M(tfpb)₂(pyr2a)]_∞ [M = Cu (1), Zn (2); tfpb = 4,4,4-trifluoro-1-phenylbutane-1,3-dionate], [M(tfpb)₂(pyz)]_∞ [M = Cu (3), Zn (4a, 4b)] and [Cu(tfpb)₂(dpet)]_∞ (5), respectively, were determined by single-crystal X-ray analysis. The coordination of metal centers in all compounds is octahedral with nitrogen ligands occupying the axial positions. Compound (1) crystallizes in the triclinic space group P\bar 1, whereas (2) crystallizes in the monoclinic space group P2/n. Differences are due to the different orientation of adjacent M(tfpb)₂ units, whereas the orientation of pyrimidin-2-amine is the same in both compounds. Polymeric chains in (1) and (2) contain intramolecular N-H...O hydrogen bonding between amino and carbonyl groups. Room-temperature structures (3) and (4a) are isomorphous adopting the monoclinic space group C2/m; however, on cooling crystals (4a) to 150 K a single-crystal-to-single-crystal transformation to (4b) possessing the triclinic space group P\bar 1 was observed. Compound (5) crystallizes in the triclinic space group P\bar 1 and contains a parallel aggregation of chains in contrast to the known structure of the non-fluorinated benzoylacetonato ligand, where chains aggregate in a perpendicular fashion. In the compounds studied intramolecular C-H...O and/or C-H...F interactions are present. The neighboring chains are linked by π...π interactions and in some compounds also by C-H...π interactions [(1), (4b), (5)].

Crystal structure and hydrogen bonding in the hydrated cocrystalline salt tryptaminium-3,5-dinitrobenzoate-quinoline-water (3/3/2/2)

The study of ternary systems is interesting because it introduces the concept of molecular preference/competition into the system where one molecule may be displaced because the association between the other two is significantly stronger. Current definitions of a tertiary system indicate that solvent molecules are excluded from the molecule count of the system and some of the latest definitions state that any molecule that is not a solid in the parent form at room temperature should also be excluded from the molecule count. In the structure of the quinoline adduct hydrate of tryptaminium 3,5-dinitrobenzoate, 3C₁₀H₁₃N₂⁺·3C₇H₃N₂O₆^-·2C₉H₇N·2H₂O, the asymmetric unit comprises multiple cation and anion species which are conformationally similar among each type set. In the crystal, a one-dimensional hydrogen-bonded supramolecular structure is generated through extensive intra- and inter-unit aminium N-H...O and N-H...N, and water O-H...O hydrogen bonds. Within the central-core hydrogen-bonding associations, conjoined cyclic R₄⁴(10), R₅³(10) and R₄⁴(12) motifs are generated. The unit is expanded into a one-dimensional column-like polymer extending along [010]. Present also in the crystal packing of the structure are a total of 19 π-π interactions involving both cation, anion and quinoline species [ring-centroid separation range = 3.395 (3)-3.797 (3) Å], as well as a number of weak C-H...O hydrogen-bonding associations. The presence of the two water molecules in the crystal structure is considered to be the principal causative factor in the low symmetry of the asymmetric unit.

Characteristic Evaluation of Graphene Oxide for Bisphenol A Adsorption in Aqueous Solution

This paper investigates the characteristics of graphene oxide (GO) for Bisphenol A (BPA) adsorption in water. Batch experiments on the influence of significant parameters were performed. While an improvement of the adsorption capacity of BPA was obtained by the increment of contact time and the initial BPA concentration, the increment of pH above 8, GO dosage, and temperature showed the reverse results. The thermodynamic study suggested that BPA adsorption on GO was an exothermic and spontaneous process. The kinetics was explained by the pseudo-second-order model which covers all steps of adsorption. The fit of the results with the Langmuir isotherm indicated the monolayer adsorption. At 298 K, the adsorption reached equilibrium within 30 min with the maximum adsorption capacity of 49.26 mg/g. The low BPA adsorption capacity of GO can be interpreted by the occurrence of oxygen-containing functional groups (OCFGs) that are able to form hydrogen bonds with the surrounding OCFGs and water molecules. This effect inhibited the role of π–π interactions that are mainly responsible for the adsorption of BPA.

Two different one-dimensional Cd(II) halide coordination polymers constructed through bridging carboxylate ligands

Two cadmium halide complexes, catena-poly[[chloridocadmium(II)]-di-μ-chlorido-[chloridocadmium(II)]-bis[μ2-4-(dimethylamino)pyridin-1-ium-1-acetate]-κ(3)O:O,O';κ(3)O,O':O], [CdCl2(C9H12N2O2)]n, (I), and catena-poly[1-cyanomethyl-1,4-diazoniabicyclo[2.2.2]octane [[dichloridocadmium(II)]-μ-oxalato-κ(4)O(1),O(2):O(1'),O(2')] monohydrate], {(C8H15N3)[CdCl2(C2O4)]·H2O}n, (II), were synthesized in aqueous solution. In (I), the Cd(II) cation is octahedrally coordinated by three O atoms from two carboxylate groups and by one terminal and two bridging chloride ligands. Neighbouring Cd(II) cations are linked together by chloride anions and bridging O atoms to form a one-dimensional zigzag chain. Hydrogen-bond interactions are involved in the formation of the two-dimensional network. In (II), each Cd(II) cation is octahedrally coordinated by four O atoms from two oxalic acid ligands and two terminal Cl(-) ligands. Neighbouring Cd(II) cations are linked together by oxalate groups to form a one-dimensional anionic chain, and the water molecules and organic cations are connected to this one-dimensional zigzag chain through hydrogen-bond interactions.

Structural consequences of weak interactions in dispirooxindole derivatives

Spiro scaffolds are being increasingly utilized in drug discovery due to their inherent three-dimensionality and structural variations, resulting in new synthetic routes to introduce spiro building blocks into more pharmaceutically active molecules. Multicomponent cascade reactions, involving the in situ generation of carbonyl ylides from α-diazocarbonyl compounds and aldehydes, and 1,3-dipolar cycloadditon with 3-arylideneoxindoles gave a novel class of dispirooxindole derivatives, namely 1,1''-dibenzyl-5'-(4-chlorophenyl)-4'-phenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-2,2''-dione, C44H33ClN2O3, (I), 1''-acetyl-1-benzyl-5'-(4-chlorophenyl)-4'-phenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-2,2''-dione, C39H29ClN2O4, (II), 1''-acetyl-1-benzyl-4',5'-diphenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-2,2''-dione, C39H30N2O4, (III), and 1''-acetyl-1-benzyl-4',5'-diphenyl-4',5'-dihydrodispiro[indoline-3,2'-furan-3',3''-indoline]-2,2''-dione acetonitrile hemisolvate, C39H30N2O4·0.5C2H3N, (IV). All four compounds exist as racemic mixtures of the SSSR and RRRS stereoisomers. In these structures, the two H atoms of the dihydrofuran ring and the two substituted oxindole rings are in a trans orientation, facilitating intramolecular C-H···O and π-π interactions. These weak interactions play a prominent role in the structural stability and aid the highly regio- and diastereoselective synthesis. In each of the four structures, the molecular assembly in the crystal is also governed by weak noncovalent interactions. Compound (IV) is the solvated analogue of (III) and the two compounds show similar structural features.

4,4'-Bipyridine-1,1'-diium acetylenedicarboxylate: a new member of the (H2bipy)[Cu(ox)2] (bipy is 4,4'-bipyridine and ox is oxalate) family

4,4'-Bipyridine-1,1'-diium (H2bipy) acetylenedicarboxylate, C10H12N2(2+)·C4O4(2-), (1), is a new member of a family of related structures with similar unit-cell parameters. The structures in this family reported previously [Chen et al. (2012). CrystEngComm, 14, 6400-6403] are (H2bipy)[Cu(ox)2] (ox is oxalate), (2), (H2bipy)[NaH(ox)2], (3), and (H2bipy)[H2(ox)2], (4). Compound (1) has a one-dimensional structure, in which H2bipy(2+) cations and acetylenedicarboxylate (ADC(2-)) anions are linked through a typical supramolecular synthon, i.e. R2(2)(7), and form linear `-cation-anion-' ribbons. Through an array of nonclassical C-H...O hydrogen bonds, adjacent ribbons interact to give two-dimensional sheets. These sheets stack to form a layered structure via π-π interactions between the H2bipy(2+) cations of neighbouring layers. The supramolecular isostructurality of compounds (1)-(4) is ascribed to the synergistic effect of multiple interactions in these structures. The balanced strong and weak intermolecular interactions stabilizing this structure type include strong charge-assisted N-H...O hydrogen bonds, C-H...O contacts and π-π interactions.

Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate

The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen-bonded centrosymmetric dimers, which are further connected by π-π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single-ion anisotropy, D, which arises from the reduced local symmetry of the cis-NiO2N4 chromophore. The fitting of the variable-temperature magnetic data (2-300 K) gives g(iso) = 2.134 and D/hc = 3.13 cm(-1).

Mechanochemistry in Polymers with Supramolecular Mechanophores

Mechanochemistry is a burgeoning field of materials science. Inspired by nature, many scientists have looked at different ways to introduce weak bonds into polymeric materials to impart them with function and in particular mechano-responsiveness. In the following sections, the incorporation of some of the weakest bonds, i.e. non-covalent bonds, into polymeric solids is being surveyed. This review covers sequentially π-π interactions, H-bonding and metal-ligand coordination bonds and tries to highlight some of the advantages and limitations of such systems, while providing some key perspective of what may come next in this tantalizing field.

New insights into the interactions between cork chemical components and pesticides. The contribution of π-π interactions, hydrogen bonding and hydrophobic effect

The role of chemical components of cork in the sorption of several pesticides has been investigated. For this purpose raw cork and three cork extracted fractions (i.e. cork free of aliphatic extractives, cork free of all extractives and cork free of all extractives and suberin) were used as sorbent of three ionic pesticides (propazine, 2,4-dichlorophenoxy acetic acid (2,4-D) and alachlor) and five non-ionic pesticides (chlorpyrifos, isoproturon, metamitron, methomyl and oxamyl) with a logKow within the range -0.47 to 4.92. The effect of cations on the ionic pesticides, propazine and 2,4-D sorption was also analyzed. Results indicated that the highest yields were obtained for chlorpyrifos and alachlor sorption onto raw cork (>55%). After removal of aliphatic extractives sorption of all pesticides increased that ranged from 3% for propazine to 31% for alachlor. In contrast, removal of phenolic extractives caused a sorption decrease. Low sorption yields were obtained for hydrophobic pesticides such as metamitron, oxamyl and methomyl (<11%) by using all cork fractions and extremely low when using raw cork (<1%). FTIR analysis was useful to indicate that lignin moieties were the main components involved on the sorption process. Modelling calculations evidenced that π-stacking interactions with the aromatic groups of lignin play a major role in determining the adsorption properties of cork toward aromatic pesticides. Results presented in this paper gain insights into the cork affinities for pesticides and the interactions involved in the sorption process and also enables to envisage sorption affinity of cork for other organic pollutants.

Structure determination of three furan-substituted benzimidazoles and calculation of π-π and C-H···π interaction energies

The synthesis and structural characterization of 2-(furan-2-yl)-1-(furan-2-ylmethyl)-1H-benzimidazole [C16H12N2O2, (I)], 2-(furan-2-yl)-1-(furan-2-ylmethyl)-1H-benzimidazol-3-ium chloride monohydrate [C16H13N2O2(+)·Cl(-)·H2O, (II)] and the hydrobromide salt 5,6-dimethyl-2-(furan-2-yl)-1-(furan-2-ylmethyl)-1H-benzimidazol-3-ium bromide [C18H17N2O2(+)·Br(-), (III)] are described. Benzimidazole (I) displays two sets of aromatic interactions, each of which involves pairs of molecules in a head-to-tail arrangement. The first, denoted set (Ia), exhibits both intermolecular C-H···π interactions between the 2-(furan-2-yl) (abbreviated as Fn) and 1-(furan-2-ylmethyl) (abbreviated as MeFn) substituents, and π-π interactions involving the Fn substituents between inversion-center-related molecules. The second, denoted set (Ib), involves π-π interactions involving both the benzene ring (Bz) and the imidazole ring (Im) of benzimidazole. Hydrated salt (II) exhibits N-H···OH2···Cl hydrogen bonding that results in chains of molecules parallel to the a axis. There is also a head-to-head aromatic stacking of the protonated benzimidazole cations in which the Bz and Im rings of one molecule interact with the Im and Fn rings of adjacent molecules in the chain. Salt (III) displays N-H···Br hydrogen bonding and π-π interactions involving inversion-center-related benzimidazole rings in a head-to-tail arrangement. In all of the π-π interactions observed, the interacting moieties are shifted with respect to each other along the major molecular axis. Basis set superposition energy-corrected (counterpoise method) interaction energies were calculated for each interaction [DFT, M06-2X/6-31+G(d)] employing atomic coordinates obtained in the crystallographic analyses for heavy atoms and optimized H-atom coordinates. The calculated interaction energies are -43.0, -39.8, -48.5, and -55.0 kJ mol(-1) for (Ia), (Ib), (II), and (III), respectively. For (Ia), the analysis was used to partition the interaction energies into the C-H···π and π-π components, which are 9.4 and 24.1 kJ mol(-1), respectively. Energy-minimized structures were used to determine the optimal interplanar spacing, the slip distance along the major molecular axis, and the slip distance along the minor molecular axis for 2-(furan-2-yl)-1H-benzimidazole.

A one-dimensional Zn(II) coordination polymer: poly[dichlorido(μ₂-1,4-phenylenediacetato-κ²O:O')bis{μ₂-1,3-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene-κ²N³:N³'}dizinc(II)]

In the title one-dimensional Zn(II) coordination polymer, [Zn(C10H8O4)(0.5)Cl(C12H12N6)]n, the asymmetric unit consists of a Zn(II) cation, a 1,3-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene ligand and half of a fully deprotonated centrosymmetric 1,4-phenylenediacetic acid ligand. The crystal structure shows a one-dimensional rotaxane-like structure. This coordination polymer is reinforced by C-H···O and C-H···Cl hydrogen bonds and π-π interactions.

A copper(I) coordination polymer incorporation the corrosion inhibitor 1H-benzotriazole: poly[μ3-benzotriazolato-κ(3)N(1):N(2):N(3)-copper(I)]

The title complex, [Cu(C6H4N3)]n, was synthesized by the reaction of cupric nitrate, 1H-benzotriazole (BTAH) and aqueous ammonia under hydrothermal conditions. The asymmetric unit contains three crystallographically independent Cu(I) cations and two 1H-benzotriazolate ligands. Two of the Cu(I) cations, one with a linear two-coordinated geometry and one with a four-coordinated tetrahedral geometry, are located on sites with crystallographically imposed twofold symmetry. The third Cu(I) cation, with a planar three-coordinated geometry, is on a general position. Two Cu(I) cations are doubly bridged by two BTA(-) ligands to afford a noncentrosymmetric planar [Cu2(BTA)2] subunit, and two [Cu2(BTA)2] subunits are arranged in an antiparallel manner to form a centrosymmetric [Cu2(BTA)2]2 secondary building unit (SBU). The SBUs are connected in a crosswise manner via the sharing of four-coordinated Cu(I) cations, Cu-N bonding and bridging by two-coordinate Cu(I) cations, resulting in a one-dimensional chain along the c axis. These one-dimensional chains are further linked by C-H···π and weak van der Waals interactions to form a three-dimensional supramolecular architecture.

Synthesis, characterization and crystal structure of the new pentahydrate of bis(2,2'-bipyridine-κ(2)N,N')(oxalato-κ(2)O(1),O(2))nickel(II)

The reaction of NiCl2, K2C2O4·H2O and 2,2'-bipyridine (bpy) in water-ethanol solution at 281 K yields light-purple needles of the new pentahydrate of bis(2,2'-bipyridine)oxalatonickel(II), [Ni(C2O4)(C10H8N2)2]·5H2O or [Ni(ox)(bpy)2]·5H2O, while at room temperature, deep-pink prisms of the previously reported tetrahydrate [Ni(ox)(bpy)2]·4H2O [Román, Luque, Guzmán-Miralles & Beitia (1995), Polyhedron, 14, 2863-2869] were gathered. The asymmetric unit in the crystal structure of the new pentahydrate incorporates the discrete molecular complex [Ni(ox)(bpy)2] and five solvent water molecules. Within the complex molecule, all three ligands are bonded as chelates. The complex molecules are involved in an extended system of hydrogen bonds with the solvent water molecules. Additionally, π-π interactions also contribute to the stabilization of the extended structure. The dehydration of the pentahydrate starts at 323 K and proceeds in at least two steps as determined by thermal analysis.

A tetranuclear organotin compound consisting of a core of three fused Sn2O2 rings

The crystal structure of the tetranuclear organotin compound 1,1,3,3,5,5,7,7-octabutyl-7-((E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoyloxy)-4,8-dimethyl-2,4,6,8-tetroxa-1,3,5,7-tetrastannatricyclo[4.2.0.0(2,5)]oct-3-yl (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate, [Sn4(C4H9)8(C21H19N2O4)2(CH3O)2(μ3-O)2], consists of a core of three fused Sn2O2 rings. The central ring consists of two Sn atoms each coordinated by two n-butyl chains, two μ3-bridging O atoms and one μ2-bridging methanolate O atom. The peripheral Sn2O2 rings consist of one of the central ring Sn atoms, and an Sn coordinated by one μ3-bridging O atom, one μ2-bridging methanolate O atom, two n-butyl chains and the carboxylate O atom of a (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate ligand (L). Despite an apparent centrosymmetric nature, the complex does not crystallize about an inversion centre. The structure packs with π-π interactions between carbazole moieties on adjacent molecules.