Layered solids based on second-sphere coordination interactions: synthesis, spectroscopic characterization, crystal structure and packing of two copper(II) naphthalene-2-sulfonates

Crystal packing and layered morphology relationships in naphthalene sulfonate compounds

The crystal structure of sodium naphthalene 2-sulfonate (Na2-NS) is reported. This compound raised the attention as a pollutant, being widely used in industry, and its intercalation in inorganic matrices, such as layered double hydroxides (LDH), could be a suitable removal strategy. The crystal structure of the title compound, despite its simplicity, is not known in the literature, so we looked for a strategy to grow crystals suitable for a single crystal study. Although many attempts were made to recrystallize it, Na2-NS grows in bunches of very thin laminae, with a high degree of mosaicity and intergrowth, explaining the absence of a reported crystal structure. The crystal structure shows layers of Na+ cations with the organic part arranged in between. The crystals grow easily in the layer plane, whilst the growth perpendicular to the layers is driven by weak non-bonding interaction and thus unfavored. The crystal packing features were related to the density of charges in the cationic layer with respect to the size of the anion. By comparing the crystal structures of 2-NS salts with different cations, and with or without an amino substituent in different positions, it was possible to find the relationship between the density of the positive charges and the deepness of interdigitation of the 2-NS moieties. We exploited this information to shed light on the structural features of 2-NS and related compounds intercalated into LDH. The X-ray powder diffraction pattern of 2-NS intercalated LDH (V. Toson, E. Conterosito, L. Palin, et al. Facile intercalation of organic molecules into hydrotalcites by liquid-assisted grinding: yield optimization by a chemometric approach. Cryst. Growth Des. 2015, 15, 5368) resulted consistent with a crystal packing characterized by the partial interdigitation of the 2-NS anions.

The coordination structure of the extracted nickel(ii) complex with a synergistic mixture containing dinonylnaphthalene sulfonic acid and 2-ethylhexyl 4-pyridinecarboxylate ester

In this paper, a synergist complex of Ni(ii) with naphthalene-2-sulfonic acid (HNS) and n-hexyl 4-pyridinecarboxylate ester (L^I), which are corresponding short chain analogues of active synergistic extractants dinonylnaphthalene sulfonic acid (HDNNS) and 2-ethylhexyl 4-pyridinecarboxylate ester (4PC, L^II), was prepared and characterized by Nuclear Magnetic Resonance (¹H-NMR), elemental analyses, Fourier Transform Infrared Spectroscopy (FT-IR) and Electrospray Ionization Mass Spectrometry (ESI-MS) spectroscopic studies. Single crystals of the nickel synergist complex have been grown from a methanol/water (10/1) solution and analyzed by single crystal X-ray diffraction. The crystal structure of the nickel synergist complex shows that Ni(ii) is coordinated by four water molecules and two monodentate L^I ligands and there is no direct interaction of the Ni(ii) with sulfonic oxygen atoms of naphthalene-2-sulfonic acid anions, while hydrogen-bonded interactions of the coordinated water molecules with sulfonic oxygen atoms of naphthalene-2-sulphate anions were observed. In addition, in order to provide parallels to solvent extraction, the extracted Ni(ii) complex with HDNNS and 4PC is also prepared and studied using FT-IR and ESI-MS technology. Compared with their corresponding free ligand, similar shifts assigned to the stretching vibration of the pyridine ring and S[double bond, length as m-dash]O in both the nickel synergist complex and the extracted Ni(ii) complex suggest that in the non-polar organic phase, Ni(ii) is also coordinated by L^II ligands, while the sulfonic oxygen atoms of dinonylnaphthalene sulfonate anions not directly bonded to Ni(ii) form hydrogen bonds with water molecules (coordinated with Ni(ii) or/and solubilized in the non-polar organic phase). For the ESI-MS spectrum of the extracted Ni(ii) complex in non-polar organic phase, there exists a peak at m/z values of 1058.76, which indicates that the extracted Ni(ii) complex in the non-polar organic phase may have a coordination structure, [Ni(H₂O)₄(L^II)₂](DNNS)₂, similar to the coordination structure of the nickel synergist complex.

trans-Diaqua-bis(ethyl-enediamine-κN,N')copper(II) bis[3-(3-pyrid-yl)propionate] dihydrate

The asymmetric unit of the title complex, [Cu(C(2)H(8)N(2))(2)(H(2)O)(2)](C(8)H(8)NO(2))(2)·2H(2)O, contains one anion, one half-cation and one water mol-ecule. The Cu(II) atom in the [Cu(en)(2)(H(2)O)(2)](2+) cation (en is ethyl-enediamine) lies on an inversion centre. The four N atoms of the en ligands in the equatorial plane around the Cu(II) atom form a slightly distorted square-planar arrangement, while the slightly distorted Jahn-Teller octa-hedral coordination is completed by two water O atoms in axial positions. In the crystal structure, intra- and inter-molecular N-H⋯O and O-H⋯O hydrogen bonds form a three-dimensional network.

Three Guest-Including Coordination Solids from a Single Crystallization: A Discrete Cage and Open-Channel Networks from 1-D Ladders and 1-D Ribbons

A study of the coordination assemblies that result from the complexation of 1,3,5-tri(4-sulfophenyl)benzene, L3-, with copper(II) in the presence of pyridine is presented. The present results offer some insights into the subtleties of designing coordination polymers and open-channel solids. From an initial crystallization, three different single crystalline solids, 1-3, are obtained. Compounds 1 and 2 are Cu pyridyl complexes of the trianionic form of the ligand whereas compound 3 is a Cu pyridyl complex of the monoprotonated form, HL2-. Compound 1 is a discrete cage complex. Compound 2 is a 1-D ladder structure that has open channels, and compound 3 is a 1-D ribbon structure that assembles into open channels. All three complexes form from the same crystallization in a ratio of 90:9:1, and all three have the same Cu coordination sphere. The exact ratio of products can be altered by varying the Cu counterion or by the addition of methanol. Addition of hexamethylenetetramine results in the exclusive formation of a different network, 4, which is structurally almost identical to the minor product 3. Single-crystal structures of all four solids are presented along with thermal analysis and IR data for the major products. A number of insights into formation of coordination assemblies are obtained. Compound 3 is discussed as an intermediate to 2, and compounds 3 and 4 offer a design paradigm for the formation of open-channel solids from 1-D building blocks.