Anion binding and extraction from solutions is currently a dynamic research topic in the field of supramolecular chemistry. A particularly challenging task is the extraction of anions with large ...hydration energies, such as the carbonate ion. Carbonate-binding complexes are also receiving increased interest due to their relevance to atmospheric CO
fixation. Nanojars are a class of self-assembled, supramolecular coordination complexes that have been shown to bind highly hydrophilic anions and to extract even the most hydrophilic ones, including carbonate, from water into aliphatic solvents. Here we present an expanded nanojar that is able to bind two carbonate ions, thus doubling the previously reported carbonate-binding capacity of nanojars. The new nanojar is characterized by detailed single-crystal X-ray crystallographic studies in the solid state and electrospray ionization mass spectrometric (including tandem MS/MS) studies in solution.
The reaction of CuSO4·5H2O, 4-chloro-pyrazole (4-Cl-pzH) and tri-ethyl-amine (Et3N) in di-methyl-formamide (DMF) produced crystals of di-aqua-hexa-kis-(μ-4-chloro-pyrazolato-κ(2) ...N:N')bis-(N,N-di-methyl-formamide)di-μ3-hydroxido-bis-(μ4-sulfato-κ(4) O:O':O'':O'')hexa-copper(II) N,N-di-methyl-formamide tetra-solvate dihydrate, Cu3(OH)(SO4)(C3H2ClN2)3(C3H7NO)(H2O)2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper-pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper-pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the Cu(II) atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square-pyramidal coordination geometry around each copper cation. The metal complex and solvent mol-ecules are involved in O-H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (10-1).
The molecular and crystal structure of a discrete Ni8(μ4-OH)6(μ-4-Rpz)122− (R = H; pz = pyrazolate anion, C3H3N2−) cluster with an unprecedented, perfectly cubic arrangement of its eight Ni centers ...is reported, along with its lower-symmetry alkyl-functionalized (R = methyl and n-octyl) derivatives. Crystals of the latter two were obtained with two identical counter-ions (Bu4N+), whereas the crystal of the complex with the parent pyrazole ligand has one Me4N+ and one Bu4N+ counter-ion. The methyl derivative incorporates 1,2-dichloroethane solvent molecules in its crystal structure, whereas the other two are solvent-free. The compounds are tetrabutylazanium tetramethylazanium hexa-μ4-hydroxido-dodeca-μ2-pyrazolato-hexahedro-octanickel, (C16H36N)(C4H12N)Ni8(C3H3N2)12(OH)6 or (Bu4N)(Me4N)Ni8(μ4-OH)6(μ-pz)12 (1), bis(tetrabutylazanium) hexa-μ4-hydroxido-dodeca-μ2-(4-methylpyrazolato)-hexahedro-octanickel 1,2-dichloroethane 7.196-solvate, (C16H36N)2Ni8(C4H5N2)12(OH)6·7.196C2H4Cl2 or (Bu4N)2Ni8(μ4-OH)6(μ-4-Mepz)12·7.196(ClCH2CH2Cl) (2), and bis(tetrabutylazanium) hexa-μ4-hydroxido-dodeca-μ2-(4-octylpyrazolato)-hexahedro-octanickel, (C16H36N)2Ni8(C11H19N2)12(OH)6 or (Bu4N)2Ni8(μ4-OH)6(μ-4-nOctpz)12 (3). All counter-ions are disordered (with the exception of one Bu4N+ in 3). Some of the octyl chains of 3 (the crystal is twinned by non-merohedry) are also disordered. Various structural features are discussed and contrasted with those of other known Ni8(μ4-OH)6(μ-4-Rpz)122− complexes, including extended three-dimensional metal–organic frameworks. In all three structures, the Ni8 units are lined up in columns.
Only two 4-halo-1H-pyrazole crystal structures are known to date (chloro and bromo, the structure of 4-iodo-1H-pyrazole has not been reported yet). The triclinic structure of 4-fluoro-1H-pyrazole, ...C3H3FN2 (P\overline{1}), reported here is not isomorphous with those of the chloro and bromo analogues (which are isomorphous, orthorhombic Pnma). To avoid sublimation during the measurement, diffraction data were collected at 150 K. Two crystallographically unique 4-fluoro-1H-pyrazole moieties linked by an N—H...N hydrogen bond are found in the asymmetric unit. Unlike the trimeric supramolecular motifs found in the structures of the chloro and bromo analogues, 4-fluoro-1H-pyrazole forms one-dimensional chains by intermolecular hydrogen bonding in the crystal.
Olfactory cues provide critical information for spatial orientation of fish, especially in the context of anadromous migrations. Born in freshwater, juveniles of anadromous fish descend to the ocean ...where they grow into adults before migrating back into freshwater to spawn. The reproductive migrants, therefore, are under selective pressures to locate streams optimal for offspring survival. Many anadromous fish use olfactory cues to orient toward suitable streams. However, no behaviorally active compounds have been identified as migratory cues. Extensive studies have shown that the migratory adult sea lampreys (Petromyzon marinus), a jawless fish, track a pheromone emitted by their stream-dwelling larvae, and, consequently, enter streams with abundant larvae. We fractionated extracts of larval sea lamprey washings with guidance from a bioassay that measures in-stream migratory behaviors of adults and identified four dihydroxylated tetrahydrofuran fatty acids, of which (+)-(2S,3S,5R)-tetrahydro-3-hydroxy-5-(1R)-1-hydroxyhexyl-2-furanoctanoic acid was shown as a migratory pheromone. The chemical structure was elucidated by spectroscopies and confirmed by chemical synthesis and X-ray crystallography. The four fatty acids were isomer-specific and enantiomer-specific in their olfactory and behavioral activities. A synthetic copy of the identified pheromone was a potent stimulant of the adult olfactory epithelium, and, at 5 × 10−13 M, replicated the extracts of larval washings in biasing adults into a tributary stream. Our results reveal a pheromone that bridges two distinct life stages and guides orientation over a large space that spans two different habitats. The identified molecule may be useful for control of the sea lamprey.
Unprecedentedly strong binding of HXO4(2-) and XO4(3-) ions (X = P or As) within self-assembled nanohosts with protein-like anion binding cavities is reported. One of the nanohosts binds two XO4(3-) ...ions at an unusually short distance, resulting in helical chirality.
Nano-sized toroidal copper(II)-hydroxide/pyrazolate assemblies, lined by H-bond donors on the inside and hydrophobic on the outside, selectively extract sulfate from mixtures with nitrate or ...perchlorate. Tetrabutylammonium "lids" seal the "nano-jars" and render the encapsulated sulfate anion completely buried and inaccessible, so that it is not precipitated by Ba(2+) ions.
Crystals of bis(tetrabutylammonium) di-μ 3 -chlorido-tris(μ 2 -4-iodopyrazolato-κ 2 N : N ′)trischloridocuprate(II) 1,4-dioxane hemisolvate, (C 16 H 36 N) 2 Cu 3 (C 3 H 2 IN 2 ) 3 Cl 5 ·0.5C 4 H 8 O ...or (Bu 4 N) 2 Cu II 3 ( μ 3 -Cl) 2 ( μ -4-I-pz) 3 Cl 3 ·0.5C 4 H 8 O, were obtained by evaporating a solution of (Bu 4 N) 2 {Cu II ( μ -OH)( μ -4-I-pz)} n CO 3 ( n = 27–31) nanojars in chloroform/1,4-dioxane. The decomposition of chloroform in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II) pyrazolate complex, and possibly Cu II ions and free 4-iodopyrazole. Cu II ions, in turn, act as catalyst for the accelerated decomposition of chloroform, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II) pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4- R -pyrazoles ( R = H, Cl, Br, Me), the Cu 3 ( μ -4-I-pz) 3 Cl 3 core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes mean length of I...Cl contacts = 3.48 (1) Å, leading to an extended two-dimensional, halogen-bonded network along (-110). The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent molecules, which create further bridges via C—H...Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.
The crystal structure of the ferromagnetically-coupled CuII3−pyrazolato complex, (Bu4N)2Cu3(μ3-Cl)2(μ-4-NO2-pz)3Cl3 (1a, pz = pyrazolato anion), was originally determined in the triclinic P-1 space ...group. By varying the recrystallization solvent and temperature, two additional true polymorphs were crystallized in the monoclinic P21/n (1b) and orthorhombic Pbca (1c) space groups. Comparison of the metric parameters of the three polymorphs revealed only minor variations in their bond lengths and angles but clearly distinguishable packing patterns. The DFT calculations showed that, in vacuum, 1a had the lowest energetic minimum (also the densest of three polymorphs), whereas 1b and 1c lay at 6.9 kcal/mol and 7.8 kcal/mol higher energies. The existence of isolable 1b and 1c is, therefore, attributed to the intermolecular interactions analyzed by the Hirshfeld methods.
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