Noncovalent Bonding in d and f-Type Coordination Compounds and Lattices. A Case Study.

Using as example the [Fe(bpca)(μ-bpca)Gd(NO)]×4CHNO×CHOH system, where Hbpca=bis(2-pyridilcarbonyl)amine), we perform the analysis of bonding components inside the d and f coordination units and between molecular entities from crystal. Aside the nominal long-range interactions between molecular components of the crystal, we considered that the bonding inside the coordination units is also not a covalent regime. We performed Density Functional Theory (DFT) calculations, with plane-waves (PW), in band-structure mode, and with atom-centred bases, by molecular procedures.

New triazole-based coordination complexes as antitumor agents against triple negative breast cancer MDA-MB-468 cell line.

The present work describes the synthesis of a new triazole based ligand 3-(3,5-dimethyl-1-pyrazol-1-yl)-1-methyl-1-1,2,4-triazole (LM) and demonstration of its coordination diversity giving rise to a family of seven new coordination complexes, namely: [Ni(LM)](ClO)·CHOS (5), [Co(LM)](ClO)·(CH)O (6), [Cd(LM)Cl] (7), [Cu(LM)NO]NO (8), [Fe(LM)](BF) (9), [Zn(LM)](BF) (10) and [Zn(LM)NO]NO (11), whose crystal structure was determined by single-crystal X-ray diffraction. Cytotoxic activity was evaluated against the MDA-MB-468 cancer cell line, which serves as a model for triple-negative breast cancer, and compared to the precursor molecule (L), as well as their coordination complexes (HO){[NiL](ClO)} (1), [CoL](ClO)·2HO (2), [CdLCl] (3) and [CuL](NO) (4), for which the crystal structure was earlier determined. Notably, cadmium complexes 3 and 7 exhibit remarkable cytotoxicity and demonstrated a high selectivity index towards cancer cells when compared to peripheral blood mononuclear cells.

Coordination Complexes Built from a Ditopic Triazole-Pyrazole Ligand with Antibacterial and Antifungal Performances.

Four mononuclear complexes (HO){[NiL](ClO)} (), [CoL](ClO)·2HO (), [CdLCl] () and [CuL](NO) () have been prepared employing a newly synthesized 1,2,4-triazole ligand: 3-(3,5-dimethyl-1-pyrazol-1-yl)-1-1,2,4-triazole (). The structures of the complexes, which crystallized in (), (), (), and (), are reviewed within the context of the cooperative effect of the hydrogen bonding network and counter anions on the supramolecular formations. Moreover, within the framework of biological activity examination, these compounds showed favorable antibacterial performances compared to those of various species of bacteria, including both Gram-positive and Gram-negative strains.

Facile In Situ Synthesis of ZnO Flower-like Hierarchical Nanostructures by the Microwave Irradiation Method for Multifunctional Textile Coatings.

ZnO nanoparticle-based multifunctional coatings were prepared by a simple, time-saving microwave method. Arginine and ammonia were used as precipitation agents, and zinc acetate dehydrate was used as a zinc precursor. Under the optimized conditions, flower-like morphologies of ZnO aggregates were obtained.

(4,5,8)-Connected Cationic Coordination Polymer Material as Explosive Chemosensor Based on the in Situ Generated AIE Tetrazolyl-Tetraphenylethylene Derivative.

A multidentate tetrazole molecule based on a TPE core, tetrakis[4-(1-tetrazol-5-yl)phenyl]ethylene (Httpe) with combined advantages of two functional groups, was synthesized by cycloaddition reaction of the corresponding organic benzonitrile derivative and azide salt. Coordination self-assembly of the in situ formed aggregation-induced emission polytetrazole luminogen with cadmium(II) ion produces an unprecedented tetrazolyl-TPE-based microporous cationic metal-organic framework (MOF) with an unusual (4,5,8T14)-connected net of {[Cd(Httpe)Cl]·(N)}, in which the Httpe serves as the first undeprotonated tetrazole ligand of octa-coordinating bridging mode. We investigate, for the first time, the utilization of the luminescent MOF containing a TPE core decorated with tetrazolyl terminals for explosive detection based on the change in fluorescence intensity, which shows high selectivity and efficiency in fluorescence quenching toward TNP detection in water solution.

Efficient and Environmentally Friendly Adsorbent Based on β-Ketoenol-Pyrazole-Thiophene for Heavy-Metal Ion Removal from Aquatic Medium: A Combined Experimental and Theoretical Study.

A new sustainable and environmentally friendly adsorbent based on a β-ketoenol-pyrazole-thiophene receptor grafted onto a silica surface was developed and applied to the removal of heavy-metal ions (Pb(II), Cu(II), Zn(II), and Cd(II)) from aquatic medium. The new material was well characterized and confirms the success of covalent binding of the receptor on the silica surface. The effect of environmental parameters on adsorption including pH, contact time, temperature, and the initial concentration were investigated.

New Substituted Benzoylthiourea Derivatives: From Design to Antimicrobial Applications.

The increasing threat of antimicrobial resistance to all currently available therapeutic agents has urged the development of novel antimicrobials. In this context, a series of new benzoylthiourea derivatives substituted with one or more fluorine atoms and with the trifluoromethyl group have been tested, synthesized, and characterized by IR, NMR, CHNS and crystal X-ray diffraction. The molecular docking has provided information regarding the binding affinity and the orientation of the new compounds to DNA gyrase B.

Highly Selective Removal of Pb(II) by a Pyridylpyrazole-β-ketoenol Receptor Covalently Bonded onto the Silica Surface.

Efficient materials capable of capturing toxic metals from water are widely needed. Herein, a new pyridylpyrazole-β-ketoenol receptor, X-ray diffraction analyzed, was covalently incorporated into the silica surface to produce solid and recyclable adsorbent particles. The new material, fully characterized, revealed extremely efficient removal of toxic metals from water, with a selectivity order of Pb(II) > Zn(II) > Cu(II) > Cd(II).

The Structural Details of Aspirin Molecules and Crystals.

We revisit, in the key of structural chemistry, one of the most known and important drugs: the aspirin. Although apparently simple, the factors determining the molecular structure and supramolecular association in crystals are not trivial. We addressed the problem from experimental and theoretical sides, considering issues from X-ray measurements and results of first-principle reconstruction of molecule and lattices by ab initio calculations.

Coordination polymers from alkaline-earth nodes and pyrazine carboxylate linkers.

A new series of alkaline-earth-metal based coordination polymers were synthesized by using a pyrazine-2,5-dicarboxylic acid (2,5-H2pzdc) ligand under hydrothermal conditions. These compounds show a variety of structural topologies, reflecting the variable coordination geometries of the alkaline-earth ions as well as the key role of the metal precursor salts. Ca, Sr, and Ba give porous three-dimensional compounds, namely [Ca(2,5-pzdc)(H2O)2]·H2O (1), [Sr(2,5-pzdc)(H2O)4]·H2O (3), [Ba(2,5-pzdc)(H2O)4]·2H2O (4) and [Ba(2,5pzdc)(H2O)2] (5), that feature one-dimensional hydrophilic channels which are filled with water molecules.

On The Density Functional Theory Treatment of Lanthanide Coordination Compounds: A Comparative Study in a Series of Cu-Ln (Ln = Gd, Tb, Lu) Binuclear Complexes.

The nontrivial aspects of electron structure in lanthanide complexes, considering ligand field (LF) and exchange coupling effects, have been investigated by means of density functional theory (DFT) calculations, taking as a prototypic case study a series of binuclear complexes [LCu(OCOMe)Ln(thd)], where L = N,N'-2,2-dimethyl-propylene-di(3-methoxy-salicylidene-iminato) and Ln = Tb, Lu, and Gd. Particular attention has been devoted to the Cu-Tb complex, which shows a quasi-degenerate nonrelativistic ground state. Challenging the limits of density functional theory (DFT), we devised a practical route to obtain different convergent solutions, permuting the starting guess orbitals in a manner resembling the run of the β electron formally originating from the f configuration of the Tb(III) over seven molecular orbitals (MOs) with predominant f-type character.

A rational synthesis of hierarchically porous, N-doped carbon from Mg-based MOFs: understanding the link between nitrogen content and oxygen reduction electrocatalysis.

Controlled mixtures of novel Mg-based metal-organic frameworks (MOFs) were prepared, with H(+) or K(+) as counterions. A linear relation was found between synthesis pH and K/H ratio in the resultant mixture, establishing the tunability of the synthesis. Upon pyrolysis, these precursor mixtures yield nitrogen-doped, hierarchically porous carbons, which have good activity towards the oxygen reduction reaction (ORR) at pH 13.

A new class of thermotropic lanthanidomesogens: Eu(III) nitrate complexes with mesogenic 4-pyridone ligands.

A new class of thermotropic lanthanidomesogens has been designed and prepared. They are based on 4-pyridone ligands that possess mesogenic cyanobiphenyl groups attached to the 4-pyridone unit via a flexible long alkyl spacer and show a very high thermal stability (decomposition temperatures near 300 °C). Depending on the alkyl length spacer, these complexes exhibit a SmA phase with transition temperatures influenced by the number of mesogenic groups employed and the spacer length.

Development and applications of the LFDFT: the non-empirical account of ligand field and the simulation of the f-d transitions by density functional theory.

Ligand field density functional theory (LFDFT) is a methodology consisting of non-standard handling of DFT calculations and post-computation analysis, emulating the ligand field parameters in a non-empirical way. Recently, the procedure was extended for two-open-shell systems, with relevance for inter-shell transitions in lanthanides, of utmost importance in understanding the optical and magnetic properties of rare-earth materials. Here, we expand the model to the calculation of intensities of f → d transitions, enabling the simulation of spectral profiles.

A novel one-dimensional chain built of vanadyl ions and pyrazine-2,5-dicarboxylate.

We present a new coordination polymer, {[VO(pzdc)(H2O)2] H2O}n, built from vanadyl and pyrazine-2,5-dicarboxylate (pzdc) ions. It consists of a one-dimensional chain of vanadyl ions linked by pzdc ions. The carboxylate groups show monodentate coordination, while the pyrazine ring is present both in non-coordinated and coordinated modes.

Highly selective water adsorption in a lanthanum metal-organic framework.

We present a new metal-organic framework (MOF) built from lanthanum and pyrazine-2,5-dicarboxylate (pyzdc) ions. This MOF, [La(pyzdc)1.5(H2O)2]⋅2 H2O, is microporous, with 1D channels that easily accommodate water molecules.

Density Functional Theory (DFT) Study of Coumarin-based Dyes Adsorbed on TiO₂ Nanoclusters-Applications to Dye-Sensitized Solar Cells.

Coumarin-based dyes have been successfully used in dye-sensitized solar cells, leading to photovoltaic conversion efficiencies of up to about 8%. Given the need to better understand the behavior of the dye adsorbed on the TiO₂ nanoparticle, we report results of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies of several coumarin-based dyes, as well as complex systems consisting of the dye bound to a TiO₂ cluster. We provide the electronic structure and simulated UV-Vis spectra of the dyes alone and adsorbed to the cluster and discuss the matching with the solar spectrum.

Magnetic anisotropy and exchange coupling in a family of isostructural Fe(III)2Ln(III)2 complexes.

The reaction of [Fe3O(O2CPh)6(H2O)3](O2CPh) with lanthanide/rare earth nitrate salts in the presence of triethanolamine (H3tea) in acetonitrile/methanol solution yields a series of compounds with isostructural tetranuclear core motifs [Fe(III)2Ln(III)2(μ3-OH)2(teaH)2(O2CCPh)6]·3MeCN (Ln = Ce (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10), Tm (11), Yb (12), Y (13)). In all cases the core topology is a defect-dicubane planar or "butterfly" Fe2Ln2 motif. Compounds 1-13 were investigated using a combination of experimental techniques and theoretical studies.

Chiral crystallization of a heterodinuclear Ni-Ln series: comprehensive analysis of the magnetic properties.

Four heterodinuclear (H(2)O)(2)NiL-Ln(NO(3))(3) complexes (Ln = Tb, Dy, Er, Yb) with a double phenoxo bridge coming from the dideprotonated Schiff-base ligand are synthesized and characterized by crystal and powder X-ray diffraction studies. This series of compounds devoid of any chiral center, crystallizes in a noncentrosymmetric space group P2(1), as the previously described (H(2)O)(2)NiL-Gd(NO(3))(3) equivalent. All four complexes are ferromagnetically coupled.

Crystal structure, fluorescence, and nanostructuration studies of the first Zn(II) anthracene-based curcuminoid.

In the following article the coordination properties of a recently reported curcuminoid 9Accm (9Accm = 1,7-(di-9-anthracene)-1,6-heptadiene-3,5-dione) with Zn(II) are reported. Preparation, crystal structure, and fluorescence spectroscopic studies of [Zn(II)(9Accm)(2)(py)] (1) are presented, as well as preliminary AFM and confocal microscopy studies on graphite surfaces. Complex 1 is the first crystallographically characterized Zn-curcuminoid in the literature; the intrinsic features of the complex are contrasted with the free ligand, 9Accm, and [Cu(II)(9Accm)(2)(py)] (2), a similar copper system, which has been recently described by us.

Structure and magnetism in Fe-Gd based dinuclear and chain systems. The interplay of weak exchange coupling and zero field splitting effects.

The synthesis and characterization of two Fe-Gd systems based on bpca(-) (Hbpca = bis(2-pyridilcarbonyl)amine) as bridging ligand is presented, taking the systems as a case study for structure-property correlations. Compound 1, [Fe(LS)(II)(μ-bpca)(2)Gd(NO(3))(2)(H(2)O)]NO(3)·2CH(3)NO(2), is a zigzag polymer, incorporating the diamagnetic low spin Fe(LS)(II) ion. The magnetism of 1 is entirely determined by the weak zero field splitting (ZFS) effect on the Gd(III) ion.

Rationalization of the lanthanide-ion-driven magnetic properties in a series of 4f-5d cyano-bridged chains.

Magnetic properties of new d-f cyanido-bridged 1D assemblies [RE(pzam)(3)(H(2)O)W(CN)(8)]·H(2)O (RE(III) = Gd, 1, Tb, 2, Dy, 3; pzam = pyrazine-2-carboxamide) were studied by temperature- and field-dependent magnetization measurements. No evidence for 3D interchain magnetic ordering is found above 2 K. Multiconfiguration ab initio calculations and subsequent modeling afforded simulation of the weak zero-field splitting effect in 1 and discussion of magnetic anisotropy in the f units of compounds 2 and 3.

Case study on a rare effect: the experimental and theoretical analysis of a manganese(III) spin-crossover system.

The six-coordinated mononuclear manganese(III) complex [Mn(5-Br-sal-N-1,5,8,12)]ClO(4) has been synthesized and isolated in crystalline form. Magnetic measurements and variable-temperature single-crystal X-ray crystallography corroborated with theoretical analysis provided firm evidence for the spin-crossover effects of this system. The monomeric complex cations are made by a hexadentate mixed-donor Schiff base ligand imposing a distorted octahedral geometry and subtle structural effects determining the manifestation of the variable spin properties of the manganese(III) centers.

Spin coupling in the supramolecular structure of a new tetra(quinoline-TEMPO)yttrium(III) complex.

The newly synthesized tetra(quinoline-TEMPO)yttrium(III) potassium salt shows interesting structural features at the molecular and supramolecular levels, revealed by the analysis of the X-ray diffraction data. The magnetic susceptibility and EPR data corroborated with structural considerations showed that the exchange and dipolar spin coupling interactions are taking place at the nodes assembling the supramolecular 2D structure. The Y(III) center shows antiprismatic octacoordination, close to the idealized D2 symmetry.

Cyanide-bridged Fe(III)-Mn(III) chain with metamagnetic properties and significant magnetic anisotropy.

The assembling of [Mn(5-MeOsalen)(H2O)]+ and [(Tp)Fe(CN)3]- affords the one-dimensional zigzag chain [(Tp)Fe(CN)3Mn(5-MeOsalen).2CH3OH]n [1; Tp- = hydrotris(pyrazolyl)borate and 5-MeOsalen2- = N,N'-ethylenebis(5-methoxysalicylideneiminate)]. The corroborated experimental and ab initio data indicate ferromagnetic Fe(III)-Mn(III) couplings and D < 0 anisotropy on Mn(III).