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The oxidation of tetra‐n‐butylammonium acetate, propionate, and pivalate was studied in rigorously anhydrous acetonitrile by conventional linear sweep and convolution voltammetry (LSV and ConV, respectively). The results suggest oxidation occurs via a concerted dissociative electron transfer pathway (RCO2−→R⋅+CO2+e−). The addition of water lowers the intrinsic barrier, signaling a possible change in mechanism to stepwise dissociative electron transfer. In rigorously dry acetonitrile, the oxidation potentials of CH3CO2− (0.60±0.09), CH3CH2CO2−, (0.47±0.05) and (CH3)3CCO2− (0.40±0.04 V vs. Ag/AgNO3 (CH3CN, 0.1 M)) are reported. These values parallel the stabilities of the resulting free radicals, consistent with a possible concerted pathway, although differential solvation of the carboxylate anions cannot be completely excluded as a contributor to this trend. [ABSTRACT FROM AUTHOR]

A semi-flexible imidazole-based urea ligand, 1-(3-(1H-imidazol-1-yl)propyl)-3-phenylurea, and three zincdicarboxylate coordination polymers possessing the ligand were synthesized and characterized. The stoichiometry and coordination number of the zinc(II) ions in the coordination polymers were found to be dependent on the positional isomers of the benzene dicarboxylate. The 1,3-benzenedicarboxylate-based coordination polymer has a one-dimensional structure, whereas, the one possessing 1,4-benzenedicarboxylate has a two-dimensional architecture. The solvent used in the synthesis of the zinc-1,3-benzenedicarboxylate coordination polymer with the ligand played a decisive role on the solvation and conformation of the ligand. The anhydrous form was obtained from a reaction in methanol in which one of the urea moieties has a puckered geometry and the assembly has layers from one-dimensional bunches of coordination chains. However, the same reaction in ethanol provided a solvate having water and ethanol as the solvents of crystallization and it has the two ligands with a stretched geometry forming a cleft-like geometry to include the ethanol molecules. The two forms were not inter-convertible. The coordination polymer with 1,4-benzenedicarboxylate has a 2-dimensional structure with 2 × 2 grids having self-included urea that held DMF molecules by hydrogen bonds. [ABSTRACT FROM AUTHOR]

Four salts, namely, 2,4,6‐triaminopyrimidinium 6‐chloronicotinate dihydrate, C4H8N5+·C6H3ClNO2−·2H2O, (I), 2,4,6‐triaminopyrimidinediium pyridine‐2,6‐dicarboxylate dihydrate, C4H9N52+·C7H3NO42−·2H2O, (II), 2,4,6‐triaminopyrimidinediium sulfate monohydrate, C4H9N52+·SO42−·H2O, (III), and 2,4,6‐triaminopyrimidinium 3,5‐dinitrobenzoate dihydrate, C4H8N5+·C7H3N2O6−·2H2O, (IV), were synthesized and characterized by X‐ray diffraction techniques. Proton transfer from the corresponding acid to the pyrimidine base has occurred in all four crystal structures. Of the four salts, two [(I) and (IV)] exist as monoprotonated bases and two [(II) and (III)] exist as diprotonated bases. In all four crystal structures, the acid interacts with the pyrimidine base through N—H...O hydrogen bonds, generating an R22(8) ring motif. The sulfate group mimics the role of the carboxylate anions. The water molecules present in compounds (I)–(IV) form water‐mediated large ring motifs. The formation of water‐mediated interactions in these crystal structures can be used as a model in the study of the hydration of nucleobases. Water molecules play an important role in building supramolecular structures. In addition to these strong hydrogen‐bonding interactions, some of the crystal structures are further enriched by aromatic π–π stacking interactions [(I) and (II)]. [ABSTRACT FROM AUTHOR]

The presence of carboxyl groups in a molecule delivers an affinity to metal cations and a sensitivity to the chemical environment, especially for an environment that can give rise to intermolecular hydrogen bonds. Carboxylate groups can also induce intramolecular interactions, such as the formation of hydrogen bonds with donor groups, leading to an impact on the conformational space of biomolecules. In the latter case, the protonation state of the amino groups plays an important role. In order to provide an accurate description of the modifications induced in a carboxylated molecule by the formation of hydrogen bonds, one needs a compromise between a quantum chemical description of the system and the necessity to take into account explicit solvent molecules. In this work, we propose a bottom‐up approach to study the conformational space and the carboxylate stretching band of (bio)organic anions. Starting from the anions in a continuum solvent, we then move to calculations using a microsolvation approach including one explicit water molecule per polar group, immersed in a continuum. Finally, we run QM/MM molecular dynamics simulations to analyze the solvation properties and to explore the anions conformational space. The results thus obtained are in good agreement with the description given by the microsolvation approach and they bring a more detailed description of the solvation shell and of the intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

[Display omitted] The unique palladium(ii) complexes, namely, (Phen)Pd((CF 3) 2 pz) 2 , (Phen)Pd(MeCF 3 pz) 2 , and [(Phen)Pd 2 (μ-dmpz) 2 (dmpz)(Hdmpz)](OAc) 2 H, where (CF 3) 2 pzH is 3,5-bis(trifluoro methyl) pyrazole, MeCF3pzH is 3-methyl-5-trifluoro methylpyrazole, Hdmpz is 3,5-dimethyl- pyrazole, Phen is 1,10-phenanthroline, have been obtained by the reactions of (Phen)Pd(OAc) 2 with the corresponding free NH -pyrazoles. According to the X-ray data, in the mononuclear pyrazolate complexes the Pdii atom has a square planar environment of nitrogen atoms of phenanthroline and two monodentate-bound pyrazolate anions. The binuclear pyrazolate-bridged complex is additionally stabilized by intramolecular hydrogen bonding of the terminal dmpz anion and Hdmpz. [ABSTRACT FROM AUTHOR]

Nisin is a natural bacteriocin that exhibits good antibacterial activity against Gram-positive bacteria. It has good solubility, stability, and activity under acidic conditions, but it becomes less soluble, stable, and active when the solution pH exceeds 6.0, which severely restricted the industrial application range of nisin as antibacterial agent. In this study, we investigated the potential of complexing nisin with a cyclodextrin carboxylate, succinic acid-β-cyclodextrin (SACD), to overcome the disadvantages. Strong hydrogen bonding was shown between the nisin and SACD, promoting the formation of nisin-SACD complexes. These complexes exhibited good solubility under neutral and alkaline conditions, and good stability after being held at high pH values during processing with high-steam sterilization. Moreover, the nisin-SACD complexes displayed significantly improved antibacterial activity against model Gram-positive bacteria (S. aureus). This study shows that complexation can improve the efficacy of nisin under neutral and alkaline situations, which may greatly broaden its application range in food, medical, and other industries. [ABSTRACT FROM AUTHOR]

Crystals of Sodium Laurate, Lauric Acid (NaLLA) were obtained and the structure was determined by single-crystal X-ray diffraction. The new crystal form is monoclinic of space group P21/c. The asymmetric unit contains two independent laurate molecules whose carboxylic/carboxylate groups are linked by a low barrier O-H...O hydrogen bond. Two lauric/laurate molecules are in a head-to-head configuration and the elongated hydrophobic chains are parallel to the long b axis. The carboxylic hydrogen atom was found to be disordered, bound on each of the two carboxylate groups in an unsymmetrical way. The non-symmetrical character of the hydrogen bond is related to the presence of two independent fatty acid molecules in the asymmetric unit and is in accordance with the different lengths of the four C-O bonds present in the molecular structure. The crystal structure was analyzed in terms of interactions on the Hirshfeld surface. The packing is stabilized by hydrogen bonds and O...Na ionic interactions in the hydrophilic layer and by C-H...H-C contacts in the hydrophobic layers which are the most enriched major contacts. [ABSTRACT FROM AUTHOR]

Three magnesium coordination compounds were obtained to explore the influence of carboxylate anions on the pattern of the formed hydrogen bonds. For their synthesis, various salts of magnesium carboxylic acid (formate, acetate, and propionate) were utilized. As an N-donor ligand, hexamethylenetetramine was employed. The supramolecular structures of the obtained compounds were determined and evaluated in Hirshfeld analysis. The length of the carbon chain of the used carboxylate anions has been proven to have a considerable impact on the self-organization of the supramolecular system by altering the three-dimensional net of the created hydrogen bonds. IR spectroscopy was used to characterize the obtained compounds, revealing significant differences between distinct systems. The thermal analysis of the investigated compounds also shows noticeable differences, demonstrating better stability of the systems containing formate anions. [ABSTRACT FROM AUTHOR]

The oxidation reaction of 3,3′,5,5′-tetramethyl-1H,1′H-4,4′-bipyrazole in the HNO3–Fe3+ system unexpectedly resulted in the formation of 1Н-pyrazole-3,4,5-tricarboxylic acid (H3PTCA) isolated as the acid sodium salt Na(H2O)2H2PTCA. The compound has a polymeric structure stabilized by rare seven-membered Н-bonded rings. [ABSTRACT FROM AUTHOR]

Ceftibuten, C15H14N4O6S2, with the systematic name (6R,7R)-7-{[(Z)-2-(2-amino-1,3-thia­zol-4-yl)-4-carb­oxy­but-2-eno­yl]amino}-8-oxo-5-thia-1-aza­bicyclo­[4.2.0]oct-2-ene-2-carb­oxy­lic acid, is a third generation, orally administered cephalosporin anti­biotic with broad anti­microbial activity and stability against extended spectrum β-lactamases. Ceftibuten can exist in various hydration states and to better understand the location of the water mol­ecules of crystallization and their effect on the structure, the crystal structures of anhydrous (I) and hydrated (II) ceftibuten were determined and both occur as zwitterions with proton transfer from the carboxyl­ate group adjacent to the β-lactam ring to the N atom of the thia­zole ring. The β-lactam ring in (I) is almost planar but the equivalent grouping in (II) is slightly buckled. In the extended structure of (I), O—HO and N—HO hydrogen bonds link the mol­ecules into a three-dimensional network. In (II), O—HOc, N—HOc, O—HOw, N—HOw and Ow—HOw (c = ceftibuten, w = water) hydrogen bonds link the components into a three-dimensional network. A large void space is present within the anhydrous crystal structure that can accommodate between two and three mol­ecules of water. [ABSTRACT FROM AUTHOR]

The reaction of three equivalents of 2-(trifluoroacetyl)pyrrole with triols [RC(CH2OH)3, R=H, CH3, CH2OH] produce triesters of pyrrole-2-carboxylic acid (1–3, respectively) which crystallize in space groups with molecular C3 symmetry coinciding with the crystallographic symmetry (averaged in the case of R=CH2OH). All are unsolvated. Compound 1 crystallizes in space group P-3 and 2 and 3 in space group P-43n. In all three, molecules form three R22(10) Hydrogen-bonded interactions between syn pyrrole N-H and carboxyl C = O on neighboring molecules. In 1, molecules are linked into infinite chains and hexamolecular rings, and the cavity at the center of the rings (site symmetry − 3) is too small to harbor a guest molecule. In 2 and 3, supramolecular assemblies radiate from four molecules with methyl and hydroxymethyl groups at tetrahedral sites in the cubic structures. Computations confirm the importance of Hydrogen-bonding in these assemblies which add to the hundreds of similar pyrrole carboxylates previously described. Applications of the R22(10) hydrogen bond motif formed between two pyrrole-2-carboxylate moieties in the design of hydrogen bonded framework. Three tripodal pyrrole-2-carboxylate compounds were synthesized, and their structure were characterized by X-ray crystallography. The three compounds self-assembled into hexamer or cubic supramolecular structures. The relibility of the motif was also proved by DFT calculations and search in Cambridge Structural Database (CSD). [ABSTRACT FROM AUTHOR]

8-(dimethylamino)-N,N-dimethylnaphthalen-1-aminium hydrogenterephthalate (PSH+TPAH-) and 8-(dimethylamino)-N,N-dimethylnaphthalen-1-aminium hydrogen-terephthalate hydrate (PSH+TPAH-·H2O) were prepared by the direct reaction of N1,N1,N8,N8-tetramethylnaphthalene-1,8-diamine, Proton Sponge (PS) © and terephthalic acid (TPAH2) in a 1:1 stoichiometric relation. The structure of both salts is constructed on the base of 1D chains defined by hydrogen bonding of the anionic carboxylate end and the carboxylic acid of TPAH-anion. Additionally for the structure of PSH+TPAH-·H2O the water molecules connect this 1D chains through hydrogen bonds, then defining a 1D-belt. In both cases the PSH+ provides balance of charge among the chains. [ABSTRACT FROM AUTHOR]

The crystal structures of catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4O:O,O′:O′)calcium] 2-methylpropanoate dihydrate], {[Ca(C4H7O2)(H2O)3](C4H7O2)·2H2O}n, (I), catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4O:O,O′:O′)strontium] 2-methylpropanoate dihydrate], {[Sr(C4H7O2)(H2O)3](C4H7O2)·2H2O}n, (II), and catena-poly[[μ-aqua-diaqua(μ3-2-methylpropanoato-κ4O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate], {[(Ca,Sr)(C4H7O2)(H2O)3](C4H7O2)·2H2O}n, (III), are related. (III) can be considered as an Sr-containing solid solution of (I), with Ca2+ and Sr2+ occupationally disordered in the ratio 0.7936 (16):0.2064 (16). (I)/(III) and (II) are homeotypic with different space groups of Pbca and Cmce, respectively. All the title crystal structures are composed of hydrophilic sheets containing the cations, carboxylate groups as well as water molecules. The hydrophobic layers, which consist of 2-methylpropanoate chains, surround the hydrophilic sheets from both sides, thus forming a sandwich-like structure extending parallel to (001). The cohesion forces within these sheets are the cation–oxygen bonds and O—H...O hydrogen bonds of moderate strength. Stacking of these sandwiches along [001] is consolidated by van der Waals forces. The structures contain columns defined by the cation–oxygen interactions in which just one symmetry-independent 2-methylpropanoate anion is included, together with three water molecules. These molecules participate in an irregular coordination polyhedron composed of eight O atoms around the cation. Additional water molecules as well as the second 2-methylpropanoate anion are not part of the coordination sphere. These molecules are connected to the above-mentioned columns by O—H...O hydrogen bonds of moderate strength. In (II), the Sr2+ cation, two of the coordinating water molecules and both anions are situated on a mirror plane with a concomitant positional disorder of the 2-methylpropyl groups; the non-coordinating water molecule also shows positional disorder of its hydrogen atom.

The title alkali propanoates poly[(μ5-propanoato)alkali(I)], M+(C2H5COO)−, with alkali/M+ = Na+, K+, Rb+ and Cs+, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydrophobic layers composed of dangling ethyl chains from the carboxylate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxylate anion, while each of the other four oxygen atoms belongs to different carboxylate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propanoates crystallizes in a different space group. The atoms are in general positions, except for the cation in K+(C2H5COO)−, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na+ and K+ propanoates, in contrast to the Rb+ and Cs+ propanoates. In the Na+ compound, the occupational parameters of the disordered methyl groups are different compared to the K+ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na+ compound with respect to that of the K+ compound, otherwise the structures are homeotypic. In Cs+ propanoate, a disorder of the methyl H atoms is observed.

The marketed formulation of pazopanib (PAZ) suffers from low and variable bioavailability because of its poor dissolution rate and photostability issues. The drug falls under Biopharmaceutics Classification System (BCS) class II of low solubility and good permeability. The hydrogen bonds and supramolecular interactions in crystalline forms of PAZ with hydroxybenzoic acids (HBAs) and dihydroxybenzoic acids (DHBAs), as well as its salts are analyzed. Ten X-ray crystal structures of PAZ which include the reference drug, a tetrahydrofuran solvate (PAZ·THF) and eight salts with HBAs/DHBAs are reported. There is proton transfer from the carboxylic group of the coformer acid to the most basic nitrogen atom of the 2-aminopyrimidine ring of PAZ in all cases. Two salts were crystallized in neat form, while the remaining six are solvates and hydrates. The crystal structure of PAZ is stabilized by sulfonamide and 2-aminopyrimidine homosynthons of N–H⋯O and N–H⋯N hydrogen bonds in an R 22 (8) ring motif. PAZ·HBA/DHBA salts consistently contain the aminopyridinium⋯carboxylate N+–H⋯O− synthon of the R 22 (8) ring. The sulfonamide homosynthon of PAZ is disrupted in preference to the formation of N–H⋯O and N–H⋯N hydrogen bonds in salt structures. The presence of an additional basic nitrogen atom in the indazole ring of PAZ promotes hydration and solvation through the O–H⋯N hydrogen bond. Whereas the formation of salts is desirable for pharmaceutical formulation, the inclusion of adventitious solvent and/or water molecules with hydroxybenzoic acid coformers in the cocrystal-salt products is a limitation for this class of coformers. The stability problem faced with hydrates and solvates of PAZ·HBA/DHBA salts means that their formation must be carried out by strictly anhydrous procedures. The consistent occurrence of the aminopyridinium⋯carboxylate N+–H⋯O− ring synthon is discussed in relation to the previous results of Aakeröy, Nangia and Zaworotko groups on similar acid–base multi-component systems. [ABSTRACT FROM AUTHOR]

We report a X-ray diffraction and molecular dynamics study on three choline-based bio-ionic liquids, choline formate, [Ch] [For], choline propanoate, [Ch][Pro], and choline butanoate, [Ch][But]. For the first time, this class of ionic liquids has been investigated by X-ray diffraction. Experimental and theoretical structure factors have been compared for each term of the series. Local structural organization has been obtained from ab initio calculations through static models of isolated ion pairs and dynamic simulations of small portions of liquids through twelve, ten, and nine ion pairs for [Ch][For], [Ch][Pro], and [Ch][But], respectively. All the theoretical models indicate that cations and anions are connected by strong hydrogen bonding and form stable ion pairs in the liquid that are reminiscent of the static ab initio ion pairs. Different structural aspects may affect the radial distribution function, like the local structure of ion pairs and the conformation of choline. When small portions of liquids have been simulated by dynamic quantum chemical methods, some key structural features of the X-ray radial distribution function were well reproduced whereas the classical force fields here applied did not entirely reproduce all the observed structural features. [ABSTRACT FROM AUTHOR]

In the presence of PPh3Me+ cations, Kemp's tricarboxylate (kta3−) complexes the uranyl cation to give [PPh3Me][UO2(kta)] (1), a triperiodic framework with cubic symmetry and srs topology. The PPh3Me+ cation is held by weak interactions into cavities with matching three-fold rotational symmetry. Comparison with the diperiodic hemi-hydrate polymorph previously reported points to the disrupting role of OH⋯O hydrogen bonds in the latter. [ABSTRACT FROM AUTHOR]

Tetrapeptides containing a Cys-Gly-Cys motif and a propensity to adopt a reverse-turn structure were synthesized to evaluate how O-, N-, H-, and aromatic π donor groups might contribute to mercury(II) complex formation. Tetrapeptides Xaa-Cys-Gly-Cys, where Xaa is glycine, glutamate, histidine, or tryptophan, were prepared and reacted with mercury(II) chloride. Their complexation with mercury(II) was studied by spectroscopic methods and computational modeling. UV-vis studies confirmed that mercury(II) binds to the cysteinyl thiolates as indicated by characteristic ligand-to-metal-charge-transfer transitions for bisthiolated S-Hg-S complexes, which correspond to 1 : 1 mercury-peptide complex formation. ESI-MS data also showed dominant 1 : 1 mercury-peptide adducts that are consistent with double deprotonations from the cysteinyl thiols to form thiolates. These complexes exhibited a strong positive circular dichroism band at 210 nm and a negative band at 193 nm, indicating that these peptides adopted a β-turn structure after binding mercury(II). Theoretical studies confirmed that optimized 1 : 1 mercury-peptide complexes adopt β-turns stabilized by intramolecular hydrogen bonds. These optimized structures also illustrate how specific N-terminal side-chain donor groups can assume intramolecular interactions and contribute to complex stability. Fluorescence quenching results provided supporting data that the indole donor group could interact with the coordinated mercury. The results from this study indicate that N-terminal side-chain residues containing carboxylate, imidazole, or indole groups can participate in stabilizing dithiolated mercury(II) complexes. These structural insights on peripheral mercury-peptide interactions provide additional understanding of the chemistry of mercury(II) with side-chain donor groups in peptides. [ABSTRACT FROM AUTHOR]

Treatment of Ni(OAc)2·4 H2O with 3,4-pyrazoledicarboxylic acid (H3pdc) and imidazole (ImH) in different metal-to-ligand ratios afforded two dinuclear nickel(II) complexes, [Ni(Hpdc)(ImH)(H2O)2]2·4 H2O (1) and [Ni(Hpdc)(ImH)2(H2O)]2·2.5 H2O (2), which were characterized by elemental analysis (EA), IR spectra and X-ray diffraction analysis and thermogravimetric analysis (TGA). Both in 1 and 2, the dinickle unit [Ni2(µ2-Hdpc)2] with six-numbered Ni2N4 ring was formed by a pair of µ2-Hpdc2− ligands linked two Ni(II) ions in N,O-chelating and N‒N-bridging fashions. The dinuclear units in 1 and 2 were expanded to 2D layer structures though hydrogen-bonding interactions between coordination water molecules, ImH molecules and carboxylate oxygen atoms, whereas the lattice water molecules in 1 and 2 just embedded in the 2D layer through intermolecular hydrogen bonding interactions. Finally, the 2D sheets in 1 were further assembled to a 3D supramolecular architecture via intermolecular C–H⋯O hydrogen bond. Besides, the luminescent and electrochemical properties of two complexes have been reported. Two dinuclear nickel(II) complexes, [Ni(Hpdc)(ImH)(H2O)2]2·4 H2O (1) and [Ni(Hpdc)(ImH)2(H2O)]2·2.5 H2O (2), were obtained by assembling of a Ni(II) ion, 3,4-pyrazoledicarboxylic acid (H3pdc) and imidazole (ImH) in different metal-to-ligand ratios. In 1 and 2, the O(C, N)−H⋯O hydrogen bonds expanded the dinuclear complexes to 3D/2D supramolecular structures, respectively. [ABSTRACT FROM AUTHOR]

The molecular structures of five diorganotin(IV) carboxylates, (I)–(V), can be categorized into two main well‐known structural types for such Sn complexes. One is the mononuclear dialkytin(IV) carboxylates with an [R2Sn(LH)2]‐type skew‐trapezoidal bipyramid, where the alkyl ligands are in pseudo‐axial positions and the O atoms from two asymmetrically coordinated bidentate carboxylate ligands are in the equatorial plane. This structure type is adopted by dibutylbis{(E)‐2‐hydroxy‐5‐[(3‐methylphenyl)diazenyl]benzoato}tin(IV) cyclohexane hemisolvate, [Sn(C4H9)2(C14H11N2O3)2]·0.5C6H12, (I), dibenzylbis{(E)‐5‐[(4‐bromophenyl)diazenyl]‐2‐hydroxybenzoato}tin(IV), [Sn(C7H7)2(C13H8BrN2O3)2], (II), and aquadibenzylbis(4‐{(E)‐[(Z)‐4‐hydroxypent‐3‐en‐2‐ylidene]amino}benzoato)tin(IV) benzene disolvate, [Sn(C7H7)2(C12H12NO3)2(H2O)]·2C6H6, (III), although the latter has an additional water ligand to give a distorted pentagonal bipyramidal coordination geometry in which the carboxylate groups are more symmetrically coordinated to the Sn atom than in (I) and (II). The other structure motif is that of the tetranuclear bis(dicarboxylatotetraorganodistannoxanes), {[R2Sn(LH)]2O}2, which contain an Sn4O2 core decorated with four bridging carboxylate ligands, plus two alkyl ligands at each SnIV centre. The complexes octabutyltetrakis{μ‐(E)‐4‐[(4‐hydroxy‐3,5‐dimethylphenyl)diazenyl]benzoato}di‐μ3‐oxido‐tetratin(IV) ethanol disolvate, [Sn4(C4H9)8(C15H13N2O3)4O2]·2C2H6O, (IV), and octabutyltetrakis{(E)‐3‐[(2‐hydroxybenzylidene)amino]propanoato}di‐μ3‐oxido‐tetratin(IV), [Sn4(C4H9)8(C10H10NO3)4O2], (V), display this motif. The structures obtained correlate with the 1:1 and 1:2 stoichiometric ratios of the dialkyltin(IV) and carboxylic acid starting materials in the syntheses. The supramolecular structures arising from consideration of secondary Sn...O interactions and/or classic hydrogen bonds include discrete molecules for (V), centrosymmetric dimers for (I), extended chains for (II) and (III), and sheets for (IV). [ABSTRACT FROM AUTHOR]

Focusing mainly on sodium 2‐ethylhexanoate, this study reveals that the carboxylate exists as a dimer in MeOD solution as evidenced by Diffusion Ordered NMR SpectroscopY (DOSY). Two crystalline varieties with distinct polymeric structures have been synthesised and crystallographically characterised. A mixed 1,10‐phenanthroline–water solvate [{(C5H10)(C2H5)COONa.(H2O)[1,10‐phen]}2]∞ contains dimeric [Na(OH2)]2 subunits, which propagate through hydrogen bonds between O atoms of the carboxylate and OH water bonds. Adjacent polymeric chains interdigitate with each other through π−π interactions between 1,10‐phen rings. Solvent‐free sodium 2‐ethylhexanoate has five‐coordinate cations comprising one bidentate chelating and three monodentate carboxylate oxygen atoms. Here, the packing arrangement is different with the central hydrophilic (NaO2)∞ core surrounded by a wrapping of disordered alkyl groups. A similar polymeric structure is observed for the crystalline DMSO‐solvated sodium valproate [{(C3H7)(C4H8)COONa.(DMSO)}]∞. This adopts a layered arrangement comprising alternating sodium carboxylate hydrophilic layers and hydrophobic organic bilayers. [ABSTRACT FROM AUTHOR]

Four novel coordination polymers based on 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide (odabco) with the following formulas [Zn(H2O)2(HCOO)2]·odabco (1), [Zn2(OH)(odabco)2(HCOO)2](NO3) (2), [Zn(odabco) (OAc)2] (3, OAc– = acetate) and [Zn2(odabco)3(OAc)2](NO3)2 (4) are prepared in solvothermal conditions. The structure of these compounds is determined by single crystal X-ray diffraction. The coordination polymer 1 is formate containing odabco guest molecules. The coordination polymers 2-4 contain odabco as a bridging ligand with additional terminally coordinated carboxylate anions. The system of hydrogen bonds in the layered formates 1 and 2 leads to the formation of 3D supramolecular frameworks. The acetates 3 and 4 containing no strong hydrogen bonds are one-dimensional and layered coordination polymers, respectively. It is established that the nature of the carboxylate anion has a decisive effect on the structure of resulting products. [ABSTRACT FROM AUTHOR]

The title compound, {[K4Ni2(C7H6N4O7)2]·4.8H2O}n, was obtained as a result of a template reaction between oxalohydrazidehydroxamic acid, formaldehyde and nickel(II) nitrate followed by partial hydrolysis of the formed intermediate. The two independent [Ni(C7H6N4O7)]2- complex anions exhibit pseudo-CS symmetry and consist of an almost planar metal-containing fragment and a 1,3,5-oxadiazinane ring with a chair conformation disposed nearly perpendicularly with respect to the former. The central NiII atom has a square-planar N2O2 coordination arrangement formed by two amide N and two carboxylate O atoms. In the crystal, the nickel(II) complex anions form layers parallel to the ab plane. Neighboring complex anion layers are connected by layers of potassium cations for which two of the four independent cations are disordered over two sites [ratios of 0.54 (3):0.46 (3) and 0.9643 (15):0.0357 (15)]. The framework is stabilized by an extensive system of hydrogen bonds where the water molecules act as donors and the carboxylic O atoms, the amide O atoms and the oxadiazinane N atoms act as acceptors. [ABSTRACT FROM AUTHOR]

Five new lanthanide complexes, [Pr(HL1)(H2O)4]Cl2·2H2O (1), [Ho(HL1) (H2O)3]Cl2·2H2O (2), [Dy(HL1)(H2O)3]Cl2·2H2O (3), [Dy(H2L2)2(H2O)6]Cl3 (4) and [Ce(H2L3)(CH3CO2)2(H2O)2]·H2O (5), based on carboxylate ligands have been prepared. All complexes have been characterized via elemental analysis, single-crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis. According to single-crystal X-ray analysis, 1–3 and 5 are coordination polymers (CPs) with 1D zigzag chains, while 4 is a 0D structure. The 3D supramolecular structures of 1–4 are formed by the interaction of C/N − H···Cl hydrogen bonds and π···π stacking interactions. In addition, the luminescent and magnetic properties of 1–5 have been discussed. [ABSTRACT FROM AUTHOR]

In the present study the solution and coordination chemistry of copper(II)–alkyl-N-iminodiacetate systems are studied in aqueous solution by potentiometry, using ion selective copper and pH electrodes, EXAFS (extended X-ray absorption fine structure) and dye probe molecular absorption spectrophotometry. Alkyl-N-iminodiacetates with varying alkyl chain length, methyl (CH3–), n-hexyl (C6H13–), n-dodecyl (C12H25–) and n-octadecyl (C18H37–) were used to tune the amphiphilic properties of the ligands. The polar head groups have both oxygen (hard Lewis base) and nitrogen donor (border-line Lewis base) atoms. This means that metal ions with different bonding characteristics may bind these ligands differently. Furthermore, the chelating properties of the polar head group may be regulated by pH as the acid–base properties of the imine and carboxylic acid groups are different. Copper(II) forms two stable complexes with alkyl-N-iminodiacetates with short alkyl chains, present as monomers in aqueous solution, log10β1 = 11.10(2), log10β2 = 19.5(2) for methyl-N-iminodiacetate, and log10β1 = 12.22(4), log10β2 = 21.9(2) for n-hexyl-N-iminodiacetate. n-Octadecyl-N-iminodiacetic acid, present as large aggregates in acidic aqueous solution, has short strong hydrogen bonds between carboxylic acid and carboxylate groups in the surface of the aggregates, which hinder complex formation at pH values below 4, obstructs it in the pH region 4–7, while the complex formation behaves as for short-chained alkyl-N-iminodiacetates at pH > 7. The structure around copper in copper(II)–alkyl-N-iminodiacetate complexes in aqueous solution and solid state formed at different pH values and copper(II):alkyl-N-iminodiacetate ratios has been determined by EXAFS. The coordination chemistry of copper(II) shows four strong bonds in the equatorial plane, and two different Cu–O/N bond distances, ca. 0.2 Å apart, in the axial positions of a non-centrosymmetric tetragonally elongated octahedron. [ABSTRACT FROM AUTHOR]

Despite their apparent similarity, framework materials based on tetraphenylmethane and tetraphenylsilane building blocks often have quite different structures and topologies. Herein, we describe a new silicon tetraamidinium compound and use it to prepare crystalline hydrogen bonded frameworks with carboxylate anions in water. The silicon‐containing frameworks are compared with those prepared from the analogous carbon tetraamidinium: when biphenyldicarboxylate or tetrakis(4‐carboxyphenyl)methane anions were used similar channel‐containing networks are observed for both the silicon and carbon tetraamidinium. When terephthalate or bicarbonate anions were used, different products form. Insights into possible reasons for the different products are provided by a survey of the Cambridge Structural Database and quantum chemical calculations, both of which indicate that, contrary to expectations, tetraphenylsilane derivatives have less geometrical flexibility than tetraphenylmethane derivatives, that is, they are less able to distort away from ideal tetrahedral bond angles. [ABSTRACT FROM AUTHOR]

The crystal structure is reported of sodium 2-[2-(2,6-di­chloro­anilino)phen­yl]acetate 3.5-hydrate or tetra-μ-aqua-κ8O:O-deca­aqua­bis­{μ3-2-[2-(2,6-di­chloro­anilino)phen­yl]acetato-κ³O:O:O}tetra­sodium(I) bis­{2-[2-(2,6-di­chloro­anil­ino)phen­yl]acetate}, {[Na4(C14H10Cl2NO2)2(H2O)14](C14H10Cl2NO2)2}n, which re­presents a new hydrate form of the NSAID sodium diclofenac (SD). The triclinic unit cell contains one ionic compound with formula Na4(C14H10Cl2NO2)4(H2O)14, in which two symmetry-related carboxyl­ate anions C14H10Cl2NO2− are bonded to a centrosymmetric [Na4]4+ core cationic cluster, while the others are only hydrogen bonded to the cationic cluster. The conformation for the anions is similar to that found in other diclofenac compounds, and the [Na4(Ocarbox)2(H2O)14]4+ cluster displays an unprecedented geometry, which can be described as an incomplete dicubane cluster formed by face-sharing incomplete cubes. A complex framework of O—H⋯O hydrogen bonds stabilizes the crystal structure. The herein reported crystal structure for SD·3.5H2O in space group P is different from those previously reported for other hydrates, namely SD·4.75H2O (P21) and SD·5H2O (P21/m). [ABSTRACT FROM AUTHOR]

The crystal structure of the title complex, [Pb3(C4H7O2)6(H2O)2]n, was redetermined on basis of modern CCD-based single-crystal X-ray data at 120 K. The current study basically confirms the previous report [Fallon et al. (1997). Polyhedron, 16, 19–23] at 190 K, but with higher accuracy and precision. In particular, positional disorder of one of the 2-methylpropanoate anions over two sets of sites was resolved, showing a refined ratio of the disorder components of 0.535 (9):0.465 (9). The three independent cations in the structure have coordination numbers of [7 + 1], [6 + 1], and [5 + 3], with O atoms belonging either to carboxylate groups or water molecules. This arrangement leads to the formation of sheets parallel to (\overline{1}01), whereby the hydrophobic 2-methylpropanyl groups of the anions are oriented above and below the hydrophilic sheets to form a layered structure. Within a sheet, hydrogen bonds of the type Owater—H...O are formed, whereas the hydrophobic groups between adjacent layers interact through van der Waals forces.

A carboxylate⋯iodine supramolecular heterosynthon can be reliably applied in cocrystal engineering, using metal carboxylates as building blocks. Analysis of the energy framework of the exemplary paddlewheel crystal [Cu(OAc)2MeOH]2 indicates a robust 1D chain and even 2D layer long-range synthon modules, which can be intactly transferred into cocrystals. However, this approach allows the identification of a "weak link" – i.e. layers where the C–H⋯O＝C hydrogen bonds between ([Cu(OAc)2(MeOH)]2)n polymeric chains will be subject to substitution by I⋯O＝C halogen bonds during interaction with halogen bond donor co-formers. In contrast to the O–H⋯O＝C/C–H⋯O＝C catemeric crystals of pure acetic acid, the crystal design exercise based on the I⋯O＝C(carboxyl) supramolecular synthon afforded a 1 : 1 cocrystal of 1,4-C6F4I2 and CH3COOH, where the discrete centrosymmetric dimers of acetic acid are stabilized by I⋯O＝C(carboxyl) halogen bonds. [ABSTRACT FROM AUTHOR]

The crystal structures of catena-poly[[π-aqua-diaqua(π3-2-methylpropanoato- k4O:O,O':O')calcium] 2-methylpropanoate dihydrate], {[Ca(C4H7O2)(H2O)3]- (C4H7O2)2H2O}n, (I), catena-poly[[π-aqua-diaqua(π3-2-methylpropanoato- k4O:O,O0:O0)strontium] 2-methylpropanoate dihydrate], {[Sr(C4H7O2)(H2O)3]- (C4H7O2) 2H2O}n, (II), and catena-poly[[π-aqua-diaqua(π3-2-methylpropanoato- k4O:O,O0:O0)(calcium/strontium)] 2-methylpropanoate dihydrate], {[(Ca,Sr)(C4H7O2)(H2O)3](C4H7O2)2H2O}n, (III), are related. (III) can be considered as an Sr-containing solid solution of (I), with Ca2+ and Sr2+ occupationally disordered in the ratio 0.7936 (16):0.2064 (16). (I)/(III) and (II) are homeotypic with different space groups of Pbca and Cmce, respectively. All the title crystal structures are composed of hydrophilic sheets containing the cations, carboxylate groups as well as water molecules. The hydrophobic layers, which consist of 2-methylpropanoate chains, surround the hydrophilic sheets from both sides, thus forming a sandwich-like structure extending parallel to (001). The cohesion forces within these sheets are the cation-oxygen bonds and O--H O hydrogen bonds of moderate strength. Stacking of these sandwiches along [001] is consolidated by van der Waals forces. The structures contain columns defined by the cation-oxygen interactions in which just one symmetryindependent 2-methylpropanoate anion is included, together with three water molecules. These molecules participate in an irregular coordination polyhedron composed of eight O atoms around the cation. Additional water molecules as well as the second 2-methylpropanoate anion are not part of the coordination sphere. These molecules are connected to the above-mentioned columns by O-- H O hydrogen bonds of moderate strength. In (II), the Sr2+ cation, two of the coordinating water molecules and both anions are situated on a mirror plane with a concomitant positional disorder of the 2-methylpropyl groups; the noncoordinating water molecule also shows positional disorder of its hydrogen atom. [ABSTRACT FROM AUTHOR]

Here in, the condensation of boc-glycine with 2,6-anhydro-3,4,5-tri-O-benzyl-D-gluco-heptitol followed by its boc-deprotection to form 2,6-anhydro-3,4,5-tri-O-benzyl-D-gluco-heptitolyl bis-glycinate, which in turn on condensation with succinic acid/pyridine-2,6-dicarboxylic acid led to the formation of sugar-amino acid hybrid macrocyclic compounds 4, 6 and debenzylated marocyclic compound 5, having amide bonds that function as efficient host for polar, hydrogen bond acceptors and carboxylate ions. The anion inclusion capability of synthesized macrocylic hosts has been evaluated by the study of their binding with boc-GlyCOOˉ anion as guest through 1H NMR titration studies in CDCl3. The binding constant (Ka) of boc-GlyCOOˉ guest with macrocyclic hosts 4 and 6 involving succinate and pyridine-2,6-dicarboxylate linkers was found to be 9.201 × 103 and 1.437 × 104 M−1, respectively. The higher binding constant was observed in the complex of boc-GlyCOOˉ with pyridine-dicarboxylate containing host may be due to the extra rigidity & suitable conformation attained by the presence of rigid-aromatic dicarboxylate linker. [ABSTRACT FROM AUTHOR]

The title alkali propano­ates poly[(μ5-propano­ato)alkali(I)], M+(C2H5COO)−, with alkali/M+ = Na+, K+, Rb+ and Cs+, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydro­phobic layers composed of dangling ethyl chains from the carboxyl­ate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxyl­ate anion, while each of the other four oxygen atoms belongs to different carboxyl­ate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propano­ates crystallizes in a different space group. The atoms are in general positions, except for the cation in K+(C2H5COO)−, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na+ and K+ propano­ates, in contrast to the Rb+ and Cs+ propano­ates. In the Na+ compound, the occupational parameters of the disordered methyl groups are different compared to the K+ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na+ compound with respect to that of the K+ compound, otherwise the structures are homeotypic. In Cs+ propano­ate, a disorder of the methyl H atoms is observed. [ABSTRACT FROM AUTHOR]

The crystal structures of two manganese(I) complexes with ester-substituted bi­pyridine or bi­quinoline supporting ligands are reported, namely, fac-bromido­tricarbon­yl(diethyl 2,2′-bi­pyridine-4,4′-di­carboxyl­ate-κ²N,N′)mangan­ese(I), [MnBr(C16H16N2O4)(CO)3], I, and fac-bromido­tricarbon­yl(diethyl 2,2′-bi­quinoline-4,4′-di­carboxyl­ate-κ²N,N′)manganese(I), [MnBr(C24H20N2O4)(CO)3], II. In both complexes, the manganese(I) atom adopts a distorted octa­hedral coordination sphere defined by three carbonyl C atoms, a Br− anion and two N atoms from the chelating α-di­imine ligand. Both complexes show fac configurations of the carbonyl ligands. In I, the complex mol­ecules are linked by C—H...Br hydrogen bonds and aromatic π–π contacts. In II, intra­molecular C—H...O hydrogen bonds are present as well as inter­molecular C—H...O and C—H...Br hydrogen bonds and π–π inter­actions. [ABSTRACT FROM AUTHOR]

The title alkali propano­ates poly[(μ5-propano­ato)alkali(I)], M+(C2H5COO)−, with alkali/M+ = Na+, K+, Rb+ and Cs+, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydro­phobic layers composed of dangling ethyl chains from the carboxyl­ate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxyl­ate anion, while each of the other four oxygen atoms belongs to different carboxyl­ate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propano­ates crystallizes in a different space group. The atoms are in general positions, except for the cation in K+(C2H5COO)−, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na+ and K+ propano­ates, in contrast to the Rb+ and Cs+ propano­ates. In the Na+ compound, the occupational parameters of the disordered methyl groups are different compared to the K+ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na+ compound with respect to that of the K+ compound, otherwise the structures are homeotypic. In Cs+ propano­ate, a disorder of the methyl H atoms is observed. [ABSTRACT FROM AUTHOR]

The crystal structures of four new chiral [1,2,3]triazolo[5,1‐b][1,3,4]thiadiazines are described, namely, ethyl 5′‐benzoyl‐5′H,7′H‐spiro[cyclohexane‐1,6′‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine]‐3′‐carboxylate, C19H22N4O3S, ethyl 5′‐(4‐methoxybenzoyl)‐5′H,7′H‐spiro[cyclohexane‐1,6′‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine]‐3′‐carboxylate, C20H24N4O4S, ethyl 6,6‐dimethyl‐5‐(4‐methylbenzoyl)‐6,7‐dihydro‐5H‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine‐3‐carboxylate, C17H20N4O3S, and ethyl 5‐benzoyl‐6‐(4‐methoxyphenyl)‐6,7‐dihydro‐5H‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine‐3‐carboxylate, C21H20N4O4S. The crystallographic data and cell activities of these four compounds and of the structures of three previously reported similar compounds, namely, ethyl 5′‐(4‐methylbenzoyl)‐5′H,7′H‐spiro[cyclopentane‐1,6′‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine]‐3′‐carboxylate, C19H22N4O3S, ethyl 5′‐(4‐methoxybenzoyl)‐5′H,7′H‐spiro[cyclopentane‐1,6′‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine]‐3′‐carboxylate, C19H22N4O4S, and ethyl 6‐methyl‐5‐(4‐methylbenzoyl)‐6‐phenyl‐6,7‐dihydro‐5H‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine‐3‐carboxylate, C22H22N4O3S, are contrasted and compared. For both crystallization and an MTT assay, racemic mixtures of the corresponding [1,2,3]triazolo[5,1‐b][1,3,4]thiadiazines were used. The main manner of molecular packing in these compounds is the organization of either enantiomeric pairs or dimers. In both cases, the formation of two three‐centre hydrogen bonds can be detected resulting from intramolecular N—H...O and intermolecular N—H...O or N—H...N interactions. Molecules of different enantiomeric forms can also form chains through N—H...O hydrogen bonds or form layers between which only weak hydrophobic contacts exist. Unlike other [1,2,3]triazolo[5,1‐b][1,3,4]thiadiazines, ethyl 5′‐benzoyl‐5′H,7′H‐spiro[cyclohexane‐1,6′‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadiazine]‐3′‐carboxylate contains molecules of only the (R)‐enantiomer; moreover, the N—H group does not participate in any significant intermolecular interactions. Molecular mechanics methods (force field OPLS3e) and the DFT B3LYP/6‐31G+(d,p) method show that the compound forming enantiomeric pairs via weak N—H...N hydrogen bonds is subject to greater distortion of the geometry under the influence of the intermolecular interactions in the crystal. For intramolecular N—H...O and S...O interactions, an analysis of the noncovalent interactions (NCIs) was carried out. The cellular activities of the compounds were tested by evaluating their antiproliferative effect against two normal human cell lines and two cancer cell lines in terms of half‐maximum inhibitory concentration (IC50). Some derivatives have been found to be very effective in inhibiting the growth of Hela cells at nanomolar and submicromolar concentrations with minimal cytotoxicity in relation to normal cells. [ABSTRACT FROM AUTHOR]

The synthesis of ethyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole- 5-carboxyl­ate via the Hantzsch reaction and partial in situ transesterification during recrystallization from methanol-d4 to the d3-methyl ester, resulting in the title solid solution, ethyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole-5-carboxyl­ate–d3-methyl 2-[(4-methyl­pyridin-2-yl)amino)-4-(pyridin-2-yl)thia­zole-5-carboxyl­ate (0.88/0.12), 0.88C17H16N4O2S·0.12C16D3H11N4O2S, is reported. The refined ratio of ethyl to d3-methyl ester in the crystal is 0.880 (6):0.120 (6). The pyridine ring is significantly twisted out of the plane of the approximately planar picoline thia­zole ester moiety. N—H...N hydrogen bonds between the secondary amino group and the pyridine nitro­gen atom of an adjacent symmetry-related mol­ecule link the mol­ecules into polymeric hydrogen-bonded zigzag tapes extending by glide symmetry in the [001] direction. There is structural evidence for intra­molecular NS chalcogen bonding and inter­molecular weak C—H...O hydrogen bonds between adjacent zigzag tapes. [ABSTRACT FROM AUTHOR]

In this paper, three isostructural 1D lanthanide complexes, [Ln(dppc)(H2O)4]n·2nH2O (Ln = Eu, Tb and Eu0.501Tb0.499, named 1-Eu, 2-Tb and Eu0.501Tb0.499), based on 3-(2,4-dicarboxylate phenyl)-2-pyridinecarboxylic acid (H3dppc) have been synthesized and characterized by elemental analysis, IR, PXRD, TG and X-ray crystallography. The complexes exhibit a 1D chain structure, which is further linked into a 3D supramolecular framework by hydrogen bonds. Tuneable emission colour of Eu0.501Tb0.499 is realized by adjusting the excitation wavelength. The sensing properties of 1-Eu and 2-Tb towards Fe3+ and aniline indicate that the two complexes have almost the same superior sensitivity and low detection limit for Fe3+ in aqueous solution, while they have different detection abilities for aniline in DMF solvent. The different detection abilities were discussed by means of PXRD, UV-vis, luminescence lifetimes and molecular surface calculations (Hirshfeld surface analysis and 2D fingerprint plots). [ABSTRACT FROM AUTHOR]

The asymmetric units of the title compounds, namely, catena-poly[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-1,3-bis(3-carboxylatopropyl)tetramethyldisiloxane-κ2O:O'], [Ni(C10H25O5Si2)(C12H24N4)]n (I), and catena-poly[[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-4-({[(3-carboxypropyl)dimethylsilyl]oxy}diethylsilyl)butanoato-κ2O:O'] perchlorate], {[Ni(C10H25O5Si2)(C12H24N4)]ClO4}n (II), consist of one (in I) or two crystallographically non-equivalent (in II) centrosymmetric macrocyclic cations and one centrosymmetric dianion (in I) or two centrosymmetric monoanions (in II). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and the mutually trans O atoms of the carboxylate in a slightly tetragonally distorted trans-NiN4O2 octahedral coordination geometry. The crystals of both types of compounds are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] and [110] directions in I and II, respectively. In I, each polymeric chain is linked to four neighbouring ones by hydrogen bonding between the NH groups of the macrocycle and the carboxylate O atoms, thus forming a three-dimensional supramolecular network. In II, each polymeric chain contacts with only two neighbours, forming hydrogen bonds between the partially protonated carboxylic groups of the bridging ligand. As a result, a lamellar structure is formed with the layers oriented parallel to the (111) plane. [ABSTRACT FROM AUTHOR]

Diphenic acid (H2dip) has been used to synthesize nine homo- or heterometallic uranyl ion complexes under solvo-hydrothermal conditions. The diphenate ligand dip2− adopts different coordination modes, mixtures of κ2-O,O′-chelation by individual carboxylate groups, chelation involving both carboxylate groups, and bridging, resulting in different associations of the cations present. [UO2(dip)] (1), [UO2(dip)(bipy)] (2), and [UO2(dip)(phen)] (3) crystallize as monoperiodic coordination polymers, complex 1 with the bridging and both chelation modes of the ligand, and 2 and 3 with only the bis-κ2-O,O′-chelated mode and further chelation by 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen). The two isomorphous complexes [H2NMe2]2[(UO2)2(dip)3] (4) and [(UO2)2Ag2(dip)3(H2O)(CH3CN)] (5) display ladder-like monoperiodic arrangements with the hydrogen bonded H2NMe2+ or carboxylate-bound, decorating Ag+ cations occupying similar positions within the chains. [Ni(R,S-Me6cyclam)(H2O)2][UO2(dip)2] (6) contains a discrete dianionic mononuclear species, while [(UO2)2(dip)2(Hdip)2Ni(cyclam)]·2H2O·2CH3CN (7) crystallizes as a monoperiodic, heterometallic polymer, with further formation of layers through reciprocal hydrogen bonding of the carboxylic acid groups. A discrete dinuclear dianionic complex is present in [Cu(R,S-Me6cyclam)][UO2(dip)(NO3)]2 (8), which crystallizes together with [(UO2)3(dip)4Cu(R,S-Me6cyclam)(H2O)2]·6H2O (9), a diperiodic assembly in which uranyl-containing dimeric units are assembled in chains through diaxial carboxylate coordination of Cu(R,S-Me6cyclam)2+ cations, with further bridging by uranyl cations generating a network with the fes topology. The uranyl emission spectra of complexes 3, 4 and 5 show the usual vibronic fine structure, while uranyl emission in 7 is largely quenched. [ABSTRACT FROM AUTHOR]

Two hitherto unknown one-dimensional coordination polymers (1D CPs) [M(adc)(4-spy)2(H2O)2]n, (M = Mn(II) (1) and Co(II) (2); H2adc = acetylenedicarboxylic acid and 4-spy = 4-styrylpyridine) have been characterized by infrared spectra, elemental analysis, thermogravimetric analyses (TGA), powder X-ray diffraction (PXRD) patterns and single-crystal X-ray diffraction techniques. Both these compounds 1 and 2, are isostructural and construct 3D supramolecular networks by the combination of hydrogen bonding and C–H···π interactions. Interestingly, these two materials exhibit variable temperature magnetic moment. Two new isostructural coordination polymers have been synthesized using linear spacer ligand acetylenedicarboxylate and monodented 4-styrylpyridine ligands. The X-ray crystallographic analysis exhibits that both the compounds form 1D chain structures which undergo hydrogen bonding and C–H···π interactions to furnish 3D supramolecular architectures. Effect of metal ion on variable temperature magnetic moment has been studied. [ABSTRACT FROM AUTHOR]

Using the DFT method PBE0/6-31G(d, p) and taking into account the solvent, the formation of bi- and pentahedral Ni(II) complexes with carboxylate and N-containing ligands in the gas phase was studied, and ΔG° of their formation from simple compounds was estimated. The functional role of bridging groups and hydrogen bonds in the formation of polynuclear structures was revealed. A model of self-organization of penta-nuclear coordination compounds [NiII5(O2CR)8L2n(μ-OH)2]0 from binuclear complex [NiII2(O2CR)4Ln(μ-H2O)]0 was proposed, into the structure of which mononuclear NiII cations are embedding and promote proton transfer from bridging aqua ligands. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title com­pound, catena-poly[[[(perchlorato-κO)copper(II)]-μ-3-(3-carb­oxy­prop­yl)-1,5,8,12-tetra­aza-3-azonia­cyclo­tetra­decane-κ4N¹,N5,N8,N12] bis­(per­chlorate)], {[Cu(C13H30N5O2)(ClO4)](ClO4)2}n, (I), consists of a macrocyclic cation, one coordinated per­chlorate anion and two per­chlorate ions as counter-anions. The metal ion is coordinated in a tetra­gonally distorted octa­hedral geometry by the four secondary N atoms of the macrocyclic ligand, the mutually trans O atoms of the per­chlorate anion and the carbonyl O atom of the protonated carb­oxy­lic acid group of a neighbouring cation. The average equatorial Cu—N bond lengths [2.01 (6) Å] are significantly shorter than the axial Cu—O bond lengths [2.379 (8) Å for carboxyl­ate and average 2.62 (7) Å for disordered per­chlorate]. The coordinated macrocyclic ligand in (I) adopts the most energetically favourable trans-III conformation with an equatorial orientation of the substituent at the protonated distal 3-position N atom in a six-membered chelate ring. The coordination of the carb­oxy­lic acid group of the cation to a neighbouring com­plex unit results in the formation of infinite chains running along the b-axis direction, which are cross­linked by N—H∙∙∙O hydrogen bonds between the secondary amine groups of the macrocycle and O atoms of the per­chlorate counter-anions to form sheets lying parallel to the (001) plane. Additionally, the extended structure of (I) is consolidated by numerous intra- and interchain C—H∙∙∙O contacts. [ABSTRACT FROM AUTHOR]

The title compound, C15H12ClNO3, consists of a 1,2-di­hydro­quinoline-4-carb­oxyl­ate unit with 2-chloro­ethyl and propynyl substituents, where the quinoline moiety is almost planar and the propynyl substituent is nearly perpendicular to its mean plane. In the crystal, the mol­ecules form zigzag stacks along the a-axis direction through slightly offset π-stacking inter­actions between inversion-related quinoline moieties which are tied together by inter­molecular C—HPrpn­yl···OCarbx and C—HChlethy···OCarbx (Prpnyl = propynyl, Carbx = carboxyl­ate and Chlethy = chloro­eth­yl) hydrogen bonds. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from HH (29.9%), H···O/O···H (21.4%), H···C/C···H (19.4%), H···Cl/Cl···H (16.3%) and C···C (8.6%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HPrpn­yl···OCarbx and C—HChlethy···OCarbx hydrogen bond energies are 67.1 and 61.7 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. [ABSTRACT FROM AUTHOR]

Resistance of Neisseria gonorrhoeae to extended-spectrum cephalosporins (ESCs) has become a major threat to human health. The primary mechanism by which N. gonorrhoeae becomes resistant to ESCs is by acquiring a mosaic penA allele, encoding penicillin-binding protein 2 (PBP2) variants containing up to 62 mutations compared with WT, of which a subset contribute to resistance. To interpret molecular mechanisms underpinning cephalosporin resistance, it is necessary to know how PBP2 is acylated by ESCs. Here, we report the crystal structures of the transpeptidase domain of WT PBP2 in complex with cefixime and ceftriaxone, along with structures of PBP2 in the apo form and with a phosphate ion bound in the active site at resolutions of 1-7-1.9 Å. These structures reveal that acylation of PBP2 by ESCs is accompanied by rotation of the Thr-498 side chain in the KTG motif to contact the cephalosporin carboxylate, twisting of the β3 strand to form the oxyanion hole, and rolling of the β3-β4 loop toward the active site. Recognition of the cephalosporin carboxylate appears to be the key trigger for formation of an acylation-competent state of PBP2. The structures also begin to explain the impact of mutations implicated in ESC resistance. In particular, a G545S mutation may hinder twisting of β3 because its side chain hydroxyl forms a hydrogen bond with Thr-498. Overall, our data suggest that acylation is initiated by conformational changes elicited or trapped by binding of ESCs and that these movements are restricted by mutations associated with resistance against ESCs. [ABSTRACT FROM AUTHOR]

Two novel diorganotin(IV) carboxylates: Ph2SnL21 and Cy2SnL22 (HL = 2-benzoylbenzoic acid), were assembled by dialkyltin oxide (alkyl = phenyl or cyclohexyl) and HL with 1:2 molar ratio. The synthesized complexes have been structurally characterized by elemental analysis, IR, 1H, 13C, 119Sn NMR spectroscopy and X-ray crystallography diffraction analyses. Both 1 and 2 are mono-nuclear dialkyltin carboxylates. The carboxylate groups of HL in 1 and 2 adopt bidentate mode to coordinate with the central Sn atom. 1D, 2D and 3D supramolecular structures formed by intermolecular hydrogen bonds, C-H···π and π···π interactions are discussed in detail. Furthermore, the preliminary luminescent properties of 1 and 2 have been studied. [ABSTRACT FROM AUTHOR]

A series of organic salts based on the monoanion of 2,3,5,6-tetrafluoroterephthalic acid were synthesized. All the compounds show characteristic hydrogen-bonded chain structures via short O–H…O hydrogen bonds between carboxyl and carboxylate groups. Upon deuteration, the overall structures of these compounds do not change. But the short O–H…O hydrogen bonds exhibit noticeable elongations (0.003–0.021 Å) of the O…O distance, known as a positive geometric H/D isotope effect. However, there is no definite relationship between the O…O distance and the geometric H/D isotope effect due to complex intermolecular interactions between the cations and anions in the crystal structures. Further investigation reveals that there is a weak negative correlation between the O…O distance and the packing effect of the cations which can be described by the plane spacing between two adjacent benzene rings of the acid. [ABSTRACT FROM AUTHOR]

The heterobifunctional organic ligand, 3-(1,2,4-triazol-4-yl)adamantane-1-carboxylate (tr-ad-COO-), was employed for the synthesis of the title silver(I) coordination polymer, {[Ag(C13H16N3O2)].2H2O}n, crystallizing in the rare orthorhombic C2221 space group. Alternation of the double μ2-1,2,4-triazole and μ2-η²:η¹-COO- (chelating, bridging mode) bridges between AgI cations supports the formation of sinusoidal coordination chains. The AgI centers possess a distorted {N2O3} square-pyramidal arrangement with τ5 = 0.30. The angular organic linkers connect the chains into a tetragonal framework with small channels along the c-axis direction occupied by water molecules of crystallization, which are interlinked via O--H···O hydrogen bonds with carboxylate groups, leading to right- and left-handed helical dispositions. [ABSTRACT FROM AUTHOR]

[Zn(OOCCH 2 C 6 H 4 OH) 2 ] n (1) and [(Phen)Zn(OOCCH 2 C 6 H 4 OH) 2 ] (2) were made by the reaction of zinc(II)acetate dihydrate with 4-hydroxyphenylacetic acid in the absence and presence of 1,10-phenenthroline, respectively. The complex 1 crystallizes as coordination polymer formed by the μ−η1,η1 carboxylate bridged tetrahedral zinc centers. The complex 2 comprises a distorted octahedral zinc center coordinated by the two bidentate carboxylates and a bidentate 1,10-phenanthroline. Thermal stabilities of the complexes were studied by TG and DTA techniques at varied heating rates (10 °C/min, 15 °C/min and 20 °C/min). Both complexes follow a two-stage degradation processes with the formation of ZnO as the final residue where complex 2 has higher energetic stability compared with complex 1. The kinetic and thermodynamic parameters were calculated from the TG curves employing the Horowitz-Metzger method. Zinc complexes were examined for their DNA binding abilities by UV–vis spectroscopic analysis and structurally rationalized by the docking studies. The binding constant values (K b) for DNA-complex interactions were found to be 7.7 × 104 M-1 and 2.94 × 104 M-1 for complexes 1 and 2 , respectively. Complex 1 interacted with DNA exclusively by hydrogen bond formation whereas complex 2 developed both hydrogen and arene-cation interactions with the active residues of DNA. • Stable zinc complexes of 4-hydroxyphenylacetic acid were synthesized. • One of the zinc complexes was containing ancillary ligand 1,10-phenenthroline. • Both the complexes revealed different geometries viz; tetrahedral and octahedral. • Kinetic and thermodynamic parameters were calculated from the TG curves. • Zinc complexes were examined for their DNA binding abilities. [ABSTRACT FROM AUTHOR]

A monomeric ternary complex [Cu(tmen)(mef)2] (1) (where mef = mefenamate anion (C15H15NO21−, tmen = N,N,N′,N′-tetramethylethylenediamine) is prepared by the reaction of CuCl2·2H2O, mefenamic acid (mefH = 2-(2,3-dimethylphenyl)aminobenzoic acid), and N,N,N′,N′-tetramethylethylenediamine (tmen) in the presence of sodium hydroxide. Complex 1 is characterized by the elemental combustion analysis, UV-visible and FT–IR spectroscopy, thermal analysis, and single crystal X-ray diffraction. From the crystal structure of complex 1, it is evident that each copper(II) ion is six-coordinate and is bonded to chelating tmen, and four O atoms of two mef anions (mef1–). In the crystal, the intramolecular hydrogen bonding exists between the H atom of the –NH group of mef and the O atom of one of the coordinated carboxylate O atoms, belonging to the same mef ligand. Complex 1 is tested for antibacterial properties against four strains, including Staphylococcus aureus, Bacillus spizizenii, Escherichia coli, and Klebsiella pneumonia. The complex shows a biological activity against Staphylococcus aureus and Bacillus spizizenii. [ABSTRACT FROM AUTHOR]

Multicomponent metal‐organic frameworks (MOFs) are built up from multiple ligands that are geometrically distinct. These ligands occupy specific positions in the MOF lattice. Installing different functionalities at precise locations in the framework is an important step in making MOFs for specific applications. This can be achieved by designing functionalized ligands for multicomponent MOFs. Here, we report a simple synthetic procedure for a new tritopic triazatruxene based tricarboxylic acid, H3tat. We show that this ligand can be symmetrically derivatized with various substituents on its nitrogen centres. We report a new isoreticular series of well‐ordered quaternary MOFs based on these new triazatruxene ligands together with two linear carboxylate ligands and Zn4O clusters. These MOFs are isostructural to the previously reported MUF‐77 series and show similar high surface areas and large pore volumes. Furthermore, H‐bonding between the NH sites of the incorporated triazatruxene ligands and guest molecules is employed to modify their fluorescence behavior. [ABSTRACT FROM AUTHOR]