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The nitrogen–sulfur Schiff base proligand S-n-octyl 3-(1-phenylethylidene)dithiocarbazate, C17H26N2S2 (HL), was prepared by reaction of S-octyl dithiocarbamate with acetophenone. Treatment of HL with nickel acetate yielded the complex bis[S-n-octyl 3-(1-phenylethylidene)dithiocarbazato]nickel(II), [Ni(C17H25N2S2)2] (NiL2), which was shown to adopt a tetrahedrally distorted cis-square-planar coordination geometry, with the NiSN planes of the two ligands forming a dihedral angle of 21.66 (6)°. Changes in the geometry of the L ligand upon chelation of Ni2+ are described, involving a ca 180° rotation around the N(azomethine)—C(thiolate) bond.

The central NiII atom in the title complex, [Ni(C13H25N2S2)2], is located on an inversion center and adopts a roughly square-planar coordination environment defined by two chelating N,S donor sets of two symmetry-related ligands in a trans configuration. The Ni—N and Ni—S bond lenghts are 1.9193 (14) and 2.1788 (5) Å, respectively, with a chelating N—Ni—S bond angle of 86.05 (4)°. These data are compared with those measured for similar dithiocarbazato ligands that bear n-octyl or n-hexyl alkyl chains. Slight differences are observed with respect to the phenylethylidene derivative where the ligands are bound cis relative to one another.

In the title complex, [Ni(C14H21N2S3)2], the nickel(II) atom is located on a crystallographic inversion center and exhibits a square-planar coordination environment, being coordinated by two negatively charged N,S-chelating ligands in a trans configuration. In the crystal, the non-H atoms of the complex are practically coplanar (r.m.s. deviation of fitted atoms = 0.135 Å), and the angle between the thienyl and the chelating rings is 6.7 (1)°. The molecules stack at a distance of 3.623 (2) Å along the b-axis direction.

In the title complex, [Ni(C14H15N2O2)2], the nickel(II) atom exhibits a square-planar coordination geometry, being coordinated by two negatively charged N,O chelating ligands in a trans configuration, with the metal located on a crystallographic center of symmetry. The X-ray structural characterization showed the complex to be disordered over two orientations with refined occupancies of 0.898 (2) and 0.102 (2). The whole molecule is close to planar, the five- and six-membered rings subtending a dihedral angle of 7.5 (2)°. The crystal packing is supported by C—H...π and C—H...O interactions that form a di-periodic layered network.

The molecular and crystal structures of a benzoylhydrazine bearing an ether group, 4-[(4-methylbenzyl)oxy]benzohydrazide, C15H16N2O2, (I), and of the corresponding N′-[(thiophen-2-yl)methylidene]- derivative, 4-[(4-methylbenzyl)oxy]-N′-[(thiophen-2-yl)methylidene]benzohydrazide, C20H18N2O2S, (II), are described. The supramolecular structures of both compounds are governed by N—H...N and N—H...O hydrogen-bonding interactions. The hydrazine compound (I) shows a crystal packing with a more complex hydrogen-bonding scheme because of the NH—NH2 entity, forming a di-periodic supramolecular structure extending parallel to (100). Hydrazone molecules in (II) are hydrogen-bonded through N—H...O interactions, giving rise to the formation of ribbons parallel to [010]. Molecules of (I) and (II) show a different orientation of the carbohydrazide moiety likely to favor the crystal packing and thus hydrogen-bonding interactions.

The molecular structure of the title compound, C22H19N3O4, shows a non-coplanar conformation, with dihedral angles between the phenyl rings of 73.3 (1) and 80.9 (1)°. These deformations are induced by the crystal packing that is mainly governed by N—H...O and C—H...O hydrogen bonds, forming a mono-periodic arrangement parallel to the b axis.

Mercury (II) ions are considered the most harmful heavy metal ion and their accumulation in the human body causes several diseases so need to be detected at trace levels. The use of nanozyme-based colorimetric detection is an acknowledged and innovative method to detect heavy metal ions in water bodies. In this work, we report CuMOF nanoparticles (CuMOF NPs) synthesized using hand grinding technique. The MOF nanoparticles were characterized by FTIR, TGA, SCXRD, PXRD, FESEM and TEM. The SCXRD confirmed paddle wheel type structure and MOF exhibits interpenetrated pcu topology with point symbol {412.63}. BET analysis revealed a high surface area of 15.995 m2g-1 and pore diameter of 3.42 nm for CuMOF NPs. The MOF NPs were found to show peroxidase-like activity. The CuMOF NPs employed as the catalyst, where 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidised by Hg2+ and a bluish solution of oxidised TMB was obtained and recorded by UV–vis spectroscopy. The activity was determined with a detection limit of 0.55 μM, Km of 0.0477 M, and Vmax of 0.3125 M s−1 for TMB, and Km of 2.646 M and Vmax of 0.126 M s−1 for H2O2. The selectivity of the method was excellent and the mechanism was supported by XPS analysis. So, we provide a low-cost, eco-friendly approach for the detection of Hg2+ using CuMOF NPs.

The title compound, C17H18O3, crystallizes with three molecules in the asymmetric unit. The molecules differ in the conformation related to the ethoxy group and in the orientation of the two phenyl rings, one of which has the ethoxy group disordered over two positions with refined occupancies of 0.735:0.265 (9). In the crystal packing, the molecules are connected by weak C—H...π interactions.

In the title complex, [Ni(C23H21N2O2)2], the central NiII atom is located on an inversion centre and exhibits a slightly distorted square-planar N2O2 coordination environment. A trans-configuration of the N,O chelating ligands results from the imposed site symmetry of the central NiII atom. In the crystal, individual molecules stack along the a axis through weak π–π stacking interactions between the phenyl rings.

The non-H atoms of the title compound, C10H12N2O2, are approximately coplanar with the exception of those at the ends: the terminal allyl carbon atom and terminal hydrazide nitrogen atom are displaced from the mean plane by 0.67 (2) and 0.20 (2) Å, respectively. In the crystal, the molecules are linked by N—H...O and N—H...N hydrogen bonds, which give rise a two-dimensional network propagating in the (001) plane.

The complete molecule of the title compound, C26H34O6, is generated by a crystallographic centre of symmetry and the central octyl chain adopts an extended conformation. In the extended structure, weak C—H...π interactions link the molecules.

A new ruthenium(III) complex of molecular formula [Ru(PPh3)Cl2(L)] (1) has been synthesized using the Schiff base ligand obtained from 5-chlorosalicylaldehyde and N,N-dimethylethylenediamine, and characterized by FT-IR, UV-Vis, cyclic voltammetry and single crystal X-ray structural analysis. The metal ion exhibits a slightly distorted octahedral environment where the chelating Schiff base ligand contributes with its NNO donor set. The coordination geometry around the Ru(III) ion is completed by a PPh3 ligand and two chloride anions, and the charge balance is assured by the phenoxo oxygen of the Schiff base. With the aim to analyse the energy related to the halogen bonding interactions in solid state, a theoretical study has been performed on complex 1, by using the MEP and NCI plot computational tools, was also performed with the aim to analyse the energy related to the halogen bonding interaction. Furthermore, complex 1 shows catecholase-like activity in conversion of the model substrate 3,5-di-tert-butylcatechol (3,5-DTBC) to the corresponding 3,5-di-tert-butylquinone (3,5-DTBQ) under aerobic condition. The parameters regarding the enzymatic kinetics have been evaluated from the Lineweaver-Burk plot using the Michaelis-Menten approach of enzyme catalysis. A significant high T.O.N value (2.346×103 h-1) indicates that complex 1 has a very good catalytic efficiency towards 3,5-DTBC

The structures are described of two bis-chelated metal complexes of nickel(II) and copper(II) with S-n-hexyl 3-(1-phenylethylidene)dithiocarbazate Schiff bases in a cis configuration, namely, bis[S-n-hexyl 3-(1-phenylethylidene)dithiocarbazato-κ2N3,S]nickel(II), [Ni(C15H21N2S2)2], and bis[S-n-hexyl 3-(1-phenylethylidene)dithiocarbazato-κ2N3,S]copper(II), [Cu(C15H21N2S2)2]. In both complexes, the metals have distorted square-planar geometries. A search in the Cambridge Structural Database [Groom et al. (2016). Acta Cryst. B72, 171–179] for bis-chelated nickel(II) and copper(II) complexes with similar Schiff bases retrieved 55 and 36 hits for the two metals, respectively. An analysis of the geometrical parameters of complexes showing cis and trans configurations is reported and the values compared with those for the complexes described in this work.

The biological activity of the vanadium Schiff base complexes, which can be potentially used as insulin-mimetic compounds, was extensively studied in the last decade. Pharmacological data showed that these compounds produced a significant decrease in blood glucose level and improved liver and kidney function after two weeks of daily use. The vanadium complexes obtained so far with Schiff bases create problems, most often with cytotoxicity, very low solubility in water, difficulty in studying the crystal structure, instability at pH = 2 and transport to cells. Therefore, it is necessary to search for new organic vanadium compounds to optimize their pharmaceutical activity. Lastly, several hundred vanadium(III–V) complexes with Schiff bases were tested, controlling both the starting vanadium compound for the synthesis of complexes, as well as changing the substituents in the aromatic ring of aldehyde and hydrazide—Schiff base components. The obtained neutral compounds were highly soluble in organic solvents; however, they were insoluble in water. Therefore, the DMSO-H2O mixture was used to test the stability of the complexes. In the last studies, the synthesis and physicochemical characterization of the vanadium(V) complex with triethylamine as a cation—HTEA[VO2(L)] (where L = Schiff base formed from 5-bromosalicylaldehyde and 2-hydroxybenzhydrazide)—was described. In the formed ionic complexes, the crystal studies show additional hydrogen interactions between the cation and the complex anion. The ionic structure of such compounds should increase the solubility of the complexes in water, thus maximizing their availability in the biological systems studied.

A series of novel ONO ligands bearing an ionic pendant-armed (hereinafter indicated as ONONu, where Nu corresponds to an anionic nucleophile) were synthesized, characterized, and successfully coordinated to cobalt and manganese precursors. New air-stable cobalt (III) complexes (1–6) and manganese (II) complexes (7 and 8) were obtained and characterized. Single crystal X-ray diffraction analysis of the Co(III) compound 5 confirmed the presence of two quaternized ligands coordinated to the metal and iodide as counterion. These novel complexes were revealed to be active catalysts in the coupling reaction of carbon dioxide and propylene oxide (PO) in different degrees of success. Among these, the manganese complex 8 afforded the best results towards the formation of propylene carbonate (PC) with a productivity of 256 kg PC/(kg cat·h), achieving a TON of 4860.

Four dioxidovanadium(V) complexes with Schiff-base ligands based on 2-hydroxybenzhydrazide with four different substituted salicylaldehydes (5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 5-nitrosalicylaldehyde, 3-bromo-5-chlorosalicylaldehyde) were synthesized and described, by using V2O5 and triethylamine. The single crystal X-ray structure measurements as well as elemental analyses and IR spectra confirmed the formulas of the ionic complexes with a protonated triethylamine acting as counterion, HTEA[VO2(L)] (HL = Schiff-base ligand). The kinetic stability of the complexes at pH = 2 and 7 was discussed with respect to the neutral vanadium(V) complexes previously studied as potential insulin-mimetic agents. A correlation between the substituents in an aromatic ring of the Schiff-base ligands with crystal packing, and also with the stability of the compounds, was presented.

The present work opens with an acknowledgement to the research activity performed by Luciana Naldini while affiliated at the Università degli Studi di Sassari (Italy), in particular towards gold complexes and clusters, as a tribute to her outstanding figure in a time and a society where being a woman in science was rather difficult, hoping her achievements could be of inspiration to young female chemists in pursuing their careers against the many hurdles they may encounter. Naldini’s findings will be a key to introduce the most recent results in this field, showing how the chemistry of gold compounds has changed throughout the years, to reach levels of complexity and elegance that were once unimagined. The study of gold complexes and clusters with various phosphine ligands was Naldini’s main field of research because of the potential application of these species in diverse research areas including electronics, catalysis, and medicine. As the conclusion of a vital period of study, here we report Naldini’s last results on a hexanuclear cationic gold cluster, [(PPh3)6Au6(OH)2]2+, having a chair conformation, and on the assumption, supported by experimental data, that it comprises two hydroxyl groups. This contribution, within the fascinating field of inorganic chemistry, provides the intuition of how a simple electron counting may lead to predictable species of yet unknown molecular architectures and formulation, nowadays suggesting interesting opportunities to tune the electronic structures of similar and higher nuclearity species thanks to new spectroscopic and analytical approaches and software facilities. After several decades since Naldini’s exceptional work, the chemistry of the gold cluster has reached a considerable degree of complexity, dealing with new, single-atom precise, materials possessing interesting physico-chemical properties, such as luminescence, chirality, or paramagnetic behavior. Here we will describe some of the most significant contributions.

The nickel(II) cation of the title complex, [Ni(C17H25N2OS2)2], is located on a crystallographic inversion centre. It has a square-planar coordination geometry, with a trans configuration of the N,S-chelating ligands, as imposed by the crystal symmetry.

A new supramolecular Pb(II) complex [PbL(NO2)]n was synthesized from Pb(NO3)2, N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO2. [PbL(NO2)]n is constructed from discrete [PbL(NO2)] units with an almost ideal N2O3 square pyramidal coordination environment around Pb(II). The ligand L− is coordinated through the 2-pyridyl N-atom, one aza N-atom, and the carbonyl O-atom. The nitrite ligand binds in a κ2-O,O coordination mode through both O-atoms. The Pb(II) center exhibits a hemidirected coordination geometry with a pronounced coordination gap, which allows a close approach of two additional N-atoms arising from the N=C(O) N-atom of an adjacent molecule and from the 4-pyridyl N-atom from the another adjacent molecule, yielding a N4O3 coordination, constructed from two Pb–N and three Pb–O covalent bonds, and two Pb⋯N tetrel bonds. Dimeric units in the structure of [PbL(NO2)]n are formed by the Pb⋯N=C(O) tetrel bonds and intermolecular electrostatically enforced π+⋯π− stacking interactions between the 2- and 4-pyridyl rings and further stabilized by C–H⋯π intermolecular interactions, formed by one of the methyl H-atoms and the 4-pyridyl ring. These dimers are embedded in a 2D network representing a simplified uninodal 3-connected fes (Shubnikov plane net) topology defined by the point symbol (4∙82). The Hirshfeld surface analysis of [PbL(NO2)] revealed that the intermolecular H⋯X (X = H, C, N, O) contacts occupy an overwhelming majority of the molecular surface of the [PbL(NO2)] coordination unit. Furthermore, the structure is characterized by intermolecular C⋯C and C⋯N interactions, corresponding to the intermolecular π⋯π stacking interactions. Notably, intermolecular Pb⋯N and, most interestingly, Pb⋯H interactions are remarkable contributors to the molecular surface of [PbL(NO2)]. While the former contacts are due to the Pb⋯N tetrel bonds, the latter contacts are mainly due to the interaction with the methyl H-atoms in the π⋯π stacked [PbL(NO2)] molecules. Molecular electrostatic potential (MEP) surface calculations showed marked electrostatic contributions to both the Pb⋯N tetrel bonds and the dimer forming π+⋯π− stacking interactions. Quantum theory of atoms in molecules (QTAIM) analyses underlined the tetrel bonding character of the Pb⋯N interactions. The manifold non-covalent interactions found in this supramolecular assembly are the result of the proper combination of the polyfunctional multidentate pyridine-hydrazide ligand and the small nitrito auxiliary ligand.

(R)-9-hydroxystearic acid, (R)-9-HSA, is a chiral nonracemic hydroxyacid of natural origin possessing interesting properties as an antiproliferative agent against different cancer types. Considering its potential application for medical and pharmaceutical purposes, the structures and rheological properties of (R)-9-HSA were investigated. Oscillatory rheology measurements reveal that (R)-9-HSA gels only paraffin oil, with less efficiency and thermal stability than its positional isomer (R)-12-HSA. Conversely, (R)-9-HSA affords crystals from methanol, acetonitrile, and carbon tetrachloride. The single crystal structures obtained both at 293 K and 100 K show non-centrosymmetric twisted carboxylic acid dimers linked at the midchain OHs into long, unidirectional chains of hydrogen bonds, owing to head-tail ordering of the molecules. Synchrotron X-ray powder diffraction experiments, performed on the solids obtained from different solvents, show the occurrence of polymorphism in paraffin oil and through thermal treatment of the solid from methanol.

Two new chiral, enantiomerically pure, hybrid P-N ligands, namely (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octan-4-one (1) and (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octane (2), have been synthesized starting from L-proline. The two ligands differ in the presence or not of a carbonyl group in the diazaphosphane ring. Their coordination chemistry towards Pd(II) was studied by reacting them with [Pd(CH3)Cl(cod)]. A different behaviour was observed: ligand 2 shows the expected bidentate chelating behaviour leading to the mononuclear Pd-complex, while ligand 1 acts as a terdentate ligand giving a dinuclear species. The corresponding cationic derivatives were obtained from the palladium neutral complexes, both as mono- and dinuclear derivatives, and tested as precatalysts for styrene dimerization, yielding E-1,3-diphenyl-1-butene regio- and stereoselectively as the sole product. A detailed analysis of the catalytic behaviour is reported.

The whole molecule of the title complex, [Pd(C15H21N2S2)2], is generated by twofold rotational symmetry. The palladium(II) atom exhibits a square-planar coordination geometry, and is located on the crystallographic twofold axis that induces a cis configuration of the N,S chelating ligands. In the crystal, molecules stack along the c-axis direction and there are no significant intermolecular interactions present. The structure was refined as an inversion twin with a final BASF parameter of 0.34 (2).

In the title compound, C11H12N2S2, the dithiocarbazate group adopts an EE configuration with respect to the C=C and C=N bonds of the propenylidene group. The atoms of the propenylidene and dithiocarbazate unit are essentially co-planar, with a maximum deviation of 0.058 (1) Å; the phenyl ring forms a dihedral angle of 18.3 (1)° with this fragment. In the crystal, molecules form inversion dimers via pairs of N—H...S hydrogen bonds involving the terminal S atom.