Estimation of conventional C-Hπ (arene), unconventional C-Hπ (chelate) and C-Hπ (thiocyanate) interactions in hetero-nuclear nickel(ii)-cadmium(ii) complexes with a compartmental Schiff base

Supramolecular clumps of μ2-1,3-acetate bridges of Cd(II)-Salen complex: Synthesis, spectroscopic characterization, crystal structure, DFT quantization's, and antifungal photodynamic therapy

The article divulges the crystal growth, synthesis, and X-ray structure characterization of one centrosymmetric cadmium complex, [Cd{CdL(μ2-1,3-acetate)}2] using Salen ligand (SL). The complex is further characterized using spectroscopic and analytical techniques, including DRS, SEM-EDX, PXRD, and ICP-MS. The crystallographic study showed that the complex has a monoclinic space P21/c. Addison parameters (Ʈ) show the hexagonal geometry of the central Cd(II) metal ion. Hirshfeld surface and 2-D fingerprint confirm supramolecular contacts despite weak C-H⋯O and C-H···π interactions. Energy frameworks, FMOs, global reactivity parameters, MEP, and energy bandgap explain the complex reactivity outlook. The complex inter- and intramolecular bonding interactions were explored through natural bond orbital (NBO), QTAIM, NCI-RDG, Electron Location Function (ELF), and Localized Orbital Locator (LOL) quantization methods. In addition, the complex and its synthetic components in vitro antibacterial efficacy were investigated using Gram-positive and Gram-negative microbial strains. SAR (structure-activity relationship) correlates with biological potency. Molecular docking assessed antimicrobial potency with proteins S. aureus (PDB ID: 1JIJ), C. albicans (PDB ID: 1M7A), E. coli (PDB ID: 1T9U), P. aeruginosa (PDB ID: 2UV0), and A. Niger (PDB ID: 3K4P). The findings are backed by the Protein-Ligand Interaction Profiler (PLIP). The antifungal potency and cell viability test of C. albicans were conducted using photodynamic therapy (APDT).

Structure-directing role of CH⋯X (X = C, N, S, Cl) interactions in three ionic cobalt complexes: X-ray investigation and DFT study using QTAIM Vr predictor to eliminate the effect of pure Coulombic forces

Three cobalt complexes, namely [CoIII(HL1)2(N3)2]ClO4 (1), [CoIII(L2)(HL2)(N3)]ClO4·1.5H2O (2), and [CoIII(L3)(HL3)(NCS)]2 [CoIICl2(NCS)2] (3), where HL1 = 2-(3-(dimethylamino)propyliminomethyl)-6-methoxyphenol, HL2 = 2-(2-(dimethylamino)ethyliminomethyl)-4,6-dichlorophenol, and HL3 = 2-(2-(dimethylamino)ethyliminomethyl)-6-methoxyphenol, as potential tridentate N2O-donor Schiff base ligands, were synthesized and characterized using elemental analysis, IR and UV-vis spectroscopy, and single-crystal X-ray diffraction studies. All three were found to be monomeric ionic complexes. Complex 1 crystallizes in the orthorhombic space group Pbcn, whereas both complexes 2 and 3 crystallize in triclinic space groups, P1̄. Further, 1 and 2 are cationic complexes of octahedral cobalt(iii) with perchlorate anions, whereas complex 3 contains a cationic part of octahedral cobalt(iii) and an anionic part of tetrahedral cobalt(ii). Hydrogen-bonding interactions involving aromatic and aliphatic CH bonds as H-bond donors and the pseudo-halide co-ligands as H-bond acceptors were established, which are important aspects governing the X-ray packing. These interactions were analyzed theoretically using the quantum theory of atoms in molecules (QTAIM) and non-covalent interaction plot (NCI plot) analyses. Moreover, energy decomposition analysis (EDA) was performed to analyze the stabilization of the complexes in terms of the electrostatic, dispersion, and correlation forces.

Palladium complexes containing NNN pincer type ligands and their activities in Suzuki-Miyaura cross coupling reaction

Five new NNN pincer-type ligands and their palladium complexes were successfully synthesised and characterised by FT-IR, ¹H NMR, ¹³C NMR, and UV-vis analyses. TEM analysis was used to observe the morphological character of the black residues obtained from the fourth cycle of the reusability test. Furthermore, suitable crystals of the N²,N⁶-bis(2-tert-butylphenyl)pyridine-2,6-dicarboxamide and its palladium complex were elucidated with the X-ray single crystal diffraction method. Both the ligand and its palladium complex crystallise in a monoclinic system with space group P2₁/c for the H₂L⁴ and C2/c for the palladium complex. The structure of the pincer ligand and its palladium complex were stabilised by intramolecular and intermolecular C-H⋅⋅⋅O, C-H⋅⋅⋅N, and N-H⋅⋅⋅N contacts. A Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid was used to assess the catalytic abilities of the palladium pincer complexes. All of the prepared complexes exhibited considerable catalytic activity. However, complexes 4 (Acetonitrile-N²,N⁶-bis(2-tert-butylphenyl)pyridine-2,6-dicarboxamidopalladium(II)) and 5 (Acetonitrile-N²,N⁶-bis(2-nitrophenyl)pyridine-2,6-dicarboxamidopalladium(II)) provided almost 100% conversion with nearly 100% yield in the reaction between 4-bromotoluene and phenylboronic acid. Furthermore, these active complexes catalysed the reaction of the sterically hindered and deactivated substrates (1-Bromo-4-izobutylbenzene and 2-bromo-6-methoxynaphthalene) with phenylboronic acid, and complete conversion and yields up to 100% were achieved in a short time with the 2-bromo-6-methoxynaphthalene.

Synthesis and crystal structures of two tri- and tetra-heterometallic Ni(ii)–Mn(ii)/Ni(ii)–Co(iii) complexes from two different Ni(ii)-containing metalloligands: effective catalytic oxidase activity and Schottky device approach

The development of tri- and tetra-nuclear heterometallic Ni(ii)–Mn(ii)/Ni(ii)–Co(iii) complexes with effective catalytic oxidase activity and the Schottky device approach.

Synthesis of Ni(ii)-Mn(ii) complexes using a new mononuclear Ni(ii) complex of an unsymmetrical N2O3 donor ligand: structures, magnetic properties and catalytic oxidase activity

A new Ni(ii) complex [NiL] (complex 1) of an asymmetrically di-condensed N₂O₃ donor Schiff base ligand, N-salicylidene-N'-3-methoxysalicylidene-1,3-propanediamine (H₂L), has been synthesized and utilized for the synthesis of three heterometallic complexes, [(NiL)₂Mn(NCS)₂(CH₃OH)₂]·CH₃OH (2) [(NiL)₂Mn(N(CN)₂)₂(CH₃OH)₂]·CH₃OH (3) and [(NiL)₂Mn₂(N₃)₂(μ_1,1-N₃)₂(CH₃OH)₂] (4). Single crystal X-ray diffraction analyses show that complexes 2 and 3 have linear trinuclear structures where two tridentate O₃ donor (NiL) units are coordinated to the central octahedral Mn(ii) centre, whereas complex 4 has a centrosymmetric tetranuclear structure where two binuclear (NiL)Mn units are linked via two phenoxido and two μ_1,1-N₃ bridges. Among the heterometallic complexes (2-4), only 4 is active towards the catalytic oxidation of 3,5-di-tert-butylcatechol to the corresponding quinone. The turnover number for the aerobic oxidation of 3,5-DTBC is 935 h^-1. ESI-mass spectra have been recorded to scrutinize the mechanistic pathway of this catalytic reaction. Variable temperature magnetic susceptibility measurements suggest that complexes 2-4 are antiferromagnetically coupled with coupling constants (J) of -4.84 and -5.23 cm^-1 for complexes 2 and 3, respectively and J₁ = -2.20 cm^-1, J₂ = 1.13 cm^-1 and J₃ = -1.12 cm^-1 for complex 4. DFT calculations have been used to rationalize the magnetic super-exchange in complexes 2-4, by computing the theoretical coupling constants and analyzing the spin density plots.

On the importance of RH3C⋯N tetrel bonding interactions in the solid state of a dinuclear zinc complex with a tetradentate Schiff base ligand

The tetrel bonding and π-stacking interactions in a new dinuclear zinc complex using a tetradentate N₂O₂ donor Schiff base have been analysed energetically using DFT calculations and several computational tools.

A theoretical insight into the formation of chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and benzoate groups as σ-hole acceptors in a dinuclear copper(ii) complex

The formation of two chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and the O atoms of carboxylate groups as acceptors in a dimeric copper(ii) complex has been described.

Differentiating intramolecular spodium bonds from coordination bonds in two polynuclear zinc(ii) Schiff base complexes

Two new zinc(ii) complexes have been synthesized and characterized. Theoretical study is devoted to distinguish between conventional coordination bonds and spodium bonds between the zinc and oxygen centers.

Methylene spacer regulated variation in supramolecular assembly of zinc(ii) dicyanamide complexes with reduced Schiff base ligands: synthesis, structure and DFT study

Three tetranuclear zinc dicyanamide complexes with three potential hexadentate reduced Schiff base ligands have been synthesized and characterized. The DFT study is devoted to the analysis of the competition between C–H⋯π and π⋯π interactions.

A theoretical insight into non-covalent supramolecular interactions in the solid state structures of two octahedral iron(iii) complexes

The nature and characteristics of the C–H⋯π interactions that play an important role in crystal packing of two iron(iii) complexes have been discussed. The DFT calculations have been conducted to determine the interaction energies in these complexes.

Diminishing accessibility of electrophilic nickel(ii) centres due to incorporation of a methylene spacer in the pendant side arm of a series of heterotrinuclear nickel(ii)/sodium complexes: a DFT study using a homodesmotic equation

The ethoxy groups have a dual effect in hindering the attack of the pseudo-halides on the nickel(ii) centre and also in stabilizing the complex by intra-molecular interactions.

Designing of Pb(II)-Based Novel Coordination Polymers (CPs): Structural Elucidation and Optoelectronic Application

[Pb₂(bdc)_1.5(aiz)] _n (1) and [Pb₂(bdc)_1.5(aiz)(MeOH)₂] _n (2) (H₂bdc = 1,4-benzene dicarboxylic acid, aiz = (E)-N'-(thiophen-2-ylmethylene)isonicotinohydrazide) have been synthesized, and structural characterization has been established by X-ray analysis and thermogravimetric analysis (TGA). Here, bdc^2- links two Pb(II) centers and the aiz ligand binds the metal centers in two different manners: chelating and monodonating. Thus, polymerizations have taken place from the combination of mixed ligand system. Optical band gaps have been studied via UV measurements. Again, the experimental and calculated (from density functional theory (DFT)) band gaps agree well and the semiconducting properties of synthesized polymeric materials have been approved. Thus, optoelectronic and photonic devices can be made by this type of coordination polymers (CPs). The I-V representative curves of 1 (device-A) and 2 (device-B) in both dark and illuminated conditions show that device-A has a higher magnitude of current than device-B. Dark- and photo-conductivity values of device-A are calculated as 2.94 × 10^-6 and 6.12 × 10^-6 S m^-1, respectively, whereas for device-B, the values of dark- and photo-conductivity are 2.92 × 10^-7 and 3.66 × 10^-7 S m^-1, respectively, at room temperature.

Methylene spacer regulated variation in molecular and crystalline architectures of cobalt(iii) complexes with reduced Schiff base ligands: a combined experimental and theoretical study

Two heteronuclear cobalt(iii)/sodium complexes, [(H₂O)₂Co(H₂L¹)Na(N₃)₂] (1) and (μ-N₃)₂[(N₃)Co(H₂L²)Na]₂ (2) have been synthesized by the reaction of two compartmental reduced Schiff bases, H₂L¹ [(1,2-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)] and H₂L² [(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)], with cobalt(ii) nitrate hexahydrate in methanol. Structures of both the complexes have been confirmed by single crystal X-ray diffraction analysis. In each complex, cobalt(iii) is located in the inner N₂O₂ compartment and sodium is placed in the outer O₂O'₂ compartment of the respective ligands. In complex 1, the saturated five-membered chelate ring assumes a half-chair conformation, thereby facilitating the anti-orientations of two N-H bonds, which in turn favours the formation of very strong hydrogen bonds forming an infinite one-dimensional assembly. Formation of this one-dimensional chain is also supported by C-Hπ (arene) interactions. On the other hand, the best hydrogen bond donor NH groups are in syn disposition (as the saturated chelate ring is six-membered and assumes a chair conformation) and do not participate in the crystal packing in complex 2. However, very strong C-Hπ(N₃) interactions have been established in complex 2, where the π-system of the bridging azide ligand participates as the π-donor. A search in the Cambridge structural database (CSD) has also been carried out to investigate the abundance and directionality of the interaction using different pseudohalides. Energies of all these supramolecular interactions were estimated by DFT calculations including Grimme's dispersion correction and characterized by the NCI plot index computational tool.

Relative stability of the cis and trans isomers of octahedral cobalt(iii) complexes of the type [Co(N2O2)X2] with tetradentate salen type Schiff bases: a combined theoretical and experimental study

Energies of cis and trans isomers of a series of octahedral cobalt(iii) complexes with salen type Schiff bases have been estimated by DFT calculations.

Metal–ligand ring aromaticity in a 2D coordination polymer used as a photosensitive electronic device

14-Membered metal–ligand ring present in a photosensitive 2D coordination polymer, [Zn₂(fum)₂(4-phpy)₄(H₂O)₂] (H₂fum = fumaric acid and 4-phpy = 4-phenyl pyridine) shows aromatic character as evident by the nucleus-independent chemical shifts (NICS) calculation.

Formation of a tetranuclear supramolecule via non-covalent Pb⋯Cl tetrel bonding interaction in a hemidirected lead(ii) complex with a nickel(ii) containing metaloligand

A hetero-nuclear nickel(ii)/lead(ii) complex has been synthesized and characterized. The tetrel bonding interactions established between the σ-hole at the hemi-coordinated lead(ii) and the electron rich chlorido ligand has been analyzed by DFT study.

Non-covalent tetrel bonding interactions in hemidirectional lead(ii) complexes with nickel(ii)-salen type metalloligands

Tetrel bonding interactions have been investigated in hetero-dinuclear nickel(ii)/lead(ii) complexes using MEP and DFT calculations.

Exploring weak intermolecular interactions in thiocyanate-bonded Zn(ii) and Cd(ii) complexes with methylimidazole: crystal structures, Hirshfeld surface analysis and luminescence properties

We report the synthesis, spectroscopy and X-ray crystal structures of four Cd(ii) and Zn(ii) coordination compounds with imidazole derivatives and thiocyanate as co-ligands.

σ-Hole halogen bonding interactions in a mixed valence cobalt(iii/ii) complex and anti-electrostatic hydrogen bonding interaction in a cobalt(iii) complex: a theoretical insight

Supramolecular interactions in the solid state structures of a mixed valence cobalt(ii/iii) complex and a cobalt(iii) complex have been studied using DFT calculations.