Unsymmetrical Ligand Research Articles

Synthesis and Characterization of Lanthanide Metal Ion Complexes of New Polydentate Hydrazone Schiff Base Ligand

The new homodinuclear complexes of the general formula [Ln2L3(NO3)3] (where HL is newly synthesized 2-((2-(benzoxazol-2-yl)-2-methylhydrazono)methyl)phenol and Ln = Sm3+ (1), Eu3+ (2), Tb3+ (3a, 3b), Dy3+ (4), Ho3+ (5), Er3+ (6), Tm3+ (7), Yb3+ (8)), have been synthesized from the lanthanide(III) nitrates with the polydentate hydrazone Schiff base ligand. The flexibility of this unsymmetrical Schiff base ligand containing N2O binding moiety, attractive for lanthanide metal ions, allowed for a self-assembly of these complexes. The compounds were characterized by spectroscopic data (ESI-MS, IR, UV/Vis, luminescence) and by the X-ray structure determination of the single crystals, all of which appeared to be different solvents. The analytical data suggested 2:3 metal:ligand stoichiometry in these complexes, and this was further confirmed by the structural results. The metal cations are nine-coordinated, by nitrogen and oxygen donor atoms. The complexes are two-centered, with three oxygen atoms in bridging positions. There are two types of structures, differing by the sources of terminal (non-bridging) coordination centers (group A: two ligands, one nitro anion/one ligand, two nitro anions, group B: three ligands, three anions).

A theory-driven synthesis of symmetric and unsymmetric 1,2-bis(diphenylphosphino)ethane analogues via radical difunctionalization of ethylene

1,2-Bis(diphenylphosphino)ethane (DPPE) and its synthetic analogues are important structural motifs in organic synthesis, particularly as diphosphine ligands with a C2-alkyl-linker chain. Since DPPE is known to bind to many metal centers in a bidentate fashion to stabilize the corresponding metal complex via the chelation effect originating from its entropic advantage over monodentate ligands, it is often used in transition-metal-catalyzed transformations. Symmetric DPPE derivatives (Ar12P−CH2−CH2−PAr12) are well-known and readily prepared, but electronically and sterically unsymmetric DPPE (Ar12P−CH2−CH2−PAr22; Ar1≠Ar2) ligands have been less explored, mostly due to the difficulties associated with their preparation. Here we report a synthetic method for both symmetric and unsymmetric DPPEs via radical difunctionalization of ethylene, a fundamental C2 unit, with two phosphine-centered radicals, which is guided by the computational analysis with the artificial force induced reaction (AFIR) method, a quantum chemical calculation-based automated reaction path search tool. The obtained unsymmetric DPPE ligands can coordinate to several transition-metal salts to form the corresponding complexes, one of which exhibits distinctly different characteristics than the corresponding symmetric DPPE–metal complex.

Strong CO2 Chemisorption in a Metal-Organic Framework with Proximate Zn-OH Groups.

A novel Zn benzotriazolate metal-organic framework (MOF), [Zn9(OAc)6(bbtm)6] (1, bbtm2- = bis(benzotriazolyl)methanone, OAc- = acetate), has been synthesized and structurally characterized using micro-crystal electron diffraction. The framework contains 12-connected nonanuclear Zn clusters with Zn-OAc groups separated by short intercluster Zn···Zn distances of 6.06 Å. Postsynthetic OAc-/OH- ligand exchange followed by thermal activation generates 1a-OH, which adsorbs CO2 at very low pressures (1.37 mmol/g at 2.5 mbar) and requires an unusually high desorption temperature (>160 °C). Diffuse reflectance IR Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations have been used to interrogate the CO2 binding mechanism in 1a-OH. The formation of unsymmetric bridging carbonate ligands within the Zn···Zn pockets accompanied by strong hydrogen bonding of the carbonate with a neighboring zinc aqua ligand explains the remarkably strong CO2 affinity of 1a-OH.

A mono-nuclear Cu(II) complex of an unsymmetrical Schiff base ligand and its use to synthesise trinuclear CuII2MnII complexes showing anion dependent SMM behaviour

The effort for synthesis complexes of unsymmetrical Schiff base ligands derived from 2,2-dimethyl-1,3-propanediamine, o-hydroxyacetophenone and salicylaldehyde by modified Edler's method resulted in the isolation of mononuclear [CuL]·CH3OH (1), where H2L = N-(α-methylsalicylidene)-N′-(salicylidene)-2,2-dimethyl-1,3-propanediamine. Complex 1 on reaction with Mn(II) ion in presence of ClO4−, N(CN)2−, or N3− yielded three tri-nuclear complexes [(CuL)2Mn(CH3OH)2](ClO4)2·3H2O (2) [(CuL)2Mn(N(CN)2)2] (3) and [(CuL)2Mn(N3)2]∙2H2O (4), respectively. X-ray crystallography revealed square planar geometry of Cu(II) and distorted octahedral geometry of Mn(II) in the complexes. Temperature dependent molar magnetic susceptibility measurements illustrated overall anti-ferromagnetic coupling between the Cu(II) and Mn(II) centres in complexes 2–4 with exchange coupling parameters, J = −16.82 cm−1 and g = 2.06 for 2, J = −19.40 cm−1 and g = 2.10 for 3 and J = −18.98 cm−1 and g = 2.11 for 4. Among these hetero-metallic complexes only the azide derivative (4) presented prominent ac signals under an applied dc bias field. Cyclic voltammetry measurements showed reversible Cu(II)/Cu(I) couple for complex 1 whereas complexes 2–4 showed irreversible reduction of Cu(II).

Selective Formation of Unsymmetric Multidentate Azine-Based Ligands in Nickel(II) Complexes.

A mixture of 2-pyridine carboxaldehyde, 4-formylimidazole (or 2-methyl-4-formylimidazole), and NiCl2·6H2O in a molar ratio of 2:2:1 was reacted with two equivalents of hydrazine monohydrate in methanol, followed by the addition of aqueous NH4PF6 solution, afforded a NiII complex with two unsymmetric azine-based ligands, [Ni(HLH)2](PF6)2 (1) or [Ni(HLMe)2](PF6)2 (2), in a high yield, where HLH denotes 2-pyridylmethylidenehydrazono-(4-imidazolyl)methane and HLMe is its 2-methyl-4-imidazolyl derivative. The spectroscopic measurements and elemental analysis confirmed the phase purity of the bulk products, and the single-crystal X-ray analysis revealed the molecular and crystal structures of the NiII complexes bearing an unsymmetric HLH or HLMe azines in a tridentate κ3 N, N’, N” coordination mode. The HLH complex with a methanol solvent, 1·MeOH, crystallizes in the orthorhombic non-centrosymmetric space group P212121 with Z = 4, affording conglomerate crystals, while the HLMe complex, 2·H2O·Et2O, crystallizes in the monoclinic and centrosymmetric space group P21/n with Z = 4. In the crystal of 2·H2O·Et2O, there is intermolecular hydrogen-bonding interaction between the imidazole N–H and the neighboring uncoordinated azine-N atom, forming a one-dimensional polymeric structure, but there is no obvious magnetic interaction among the intra- and interchain paramagnetic NiII ions.

Synthesis and photophysical investigations of pyridine-pyrazolate bound boron(III) diaryl complexes

This study presents the design and synthetic pathway of unsymmetric ligands based on pyridine-pyrazolate scaffold with Donor–Acceptor (D–A) molecular arrays and their boron complexes to achieve a large Stokes shift. Intermolecular charge transfer (ICT) triggered by the uneven molecular charge distribution from electronically dense pyrazolate (donor) part of the ligands to electron-deficient boron centre (acceptor) resulted in a mega Stokes shift up to 263 nm for selected compounds while retaining the characteristic quantum efficiency and chemical stability. The photophysical properties of derivatization of pyrazolate group in the pyridine-pyrazolate scaffold of diaryl boron complexes were explored based on UV–Visible, steady-state and time-resolved fluorescence spectroscopy. An interesting dual emission along with quenching behaviour was also observed for 2-(6-methoxynaphthelene) 5-(2-pyridyl) pyrazolate boron complex (P5) due to the formation of a twisted intermolecular charge transfer (TICT) state from a locally excited (LE) state rendering it a potential candidate for sensing applications based on H-Bond quenching. In addition, the extended excited state lifetime of the reported compounds compared to classical boron-dipyrromethene (BODIPY) makes them suitable as potential probes for analytical applications requiring a longer excited state lifetime.

Formation of dimethoxy bridged dinuclear iron(III) complex of pyridoxal Schiff base with iron-catalyzed oxidative C[sbnd]N bond cleavage – Structure, magnetic properties, and DFT calculations

Mononuclear Fe(III) complex [FeL(N3)]·CH3OH, where L2– is the dianion of an unsymmetrical propyl-ethyl pentadentate Schiff base ligand condensed from pyridoxal and N-(2-aminoethyl)propane-1,3-diamine, and dinuclear Fe(III) complex [{FeL’}2(μ-OCH3)2]·2.5CH3OH·H2O, where L’2– is the dianion of tetradentate Schiff base ligand based on pyridoxal and ethylenediamine, have been synthesized and characterized by elemental analysis, X-ray structural analysis, FT-IR and mass spectrometry. Tetradentate pyridoxal Schiff base ligand L’2– of the dinuclear complex was generated in situ via iron-catalyzed oxidative CN bond cleavage of the pentadentate Schiff base. The coordination geometry around the iron(III) centers of the complexes can be described as adistorted octahedron. Magnetic investigations of [FeL(N3)]·CH3OH complex revealed that the octahedral Fe(III) center retains high-spin in the entire temperature range (2–300 K) and enabled the evaluation of the axial zero-field splitting (ZFS) parameter D = –1.78 cm−1, intermolecular exchange parameter zj́ = –1.35 cm−1 and temperature-independent paramagnetism χTIM = 0.00029 cm3mol−1. Magnetic investigations of [{FeL’}2(μ-OCH3)2]·2.5CH3OH·H2O showed that Fe(III) centers are coupled by a strong antiferromagnetic interaction (J = –94.5 cm−1). The experimental magnetic properties of the complexes were compared with the data obtained from the density functional theory (DFT) calculations.

Pseudo‐heterolepticity in Low‐Symmetry Metal‐Organic Cages

AbstractHeteroleptic metal‐organic cages, formed through integrative self‐assembly of ligand mixtures, are highly attractive as reduced symmetry supramolecular hosts. Ensuring high‐fidelity, non‐statistical self‐assembly, however, presents a significant challenge in molecular engineering due to the inherent difficulty in predicting thermodynamic energy landscapes. In this work, two conceptual strategies are described that circumvent this issue, using ligand design strategies to access structurally sophisticated metal‐organic hosts. Using these approaches, it was possible to realise cavity environments described by two inequivalent, unsymmetrical ligand frameworks, representing a significant step forward in the construction of highly anisotropic confined spaces.

Pseudo-heterolepticity in Low-Symmetry Metal-Organic Cages.

Heteroleptic metal-organic cages, formed through integrative self-assembly of ligand mixtures, are highly attractive as reduced symmetry supramolecular hosts. Ensuring high-fidelity, non-statistical self-assembly, however, presents a significant challenge in molecular engineering due to the inherent difficulty in predicting thermodynamic energy landscapes. In this work, two conceptual strategies are described that circumvent this issue, using ligand design strategies to access structurally sophisticated metal-organic hosts. Using these approaches, it was possible to realise cavity environments described by two inequivalent, unsymmetrical ligand frameworks, representing a significant step forward in the construction of highly anisotropic confined spaces.

Vanadium complexes bearing the bulky bis(imino)pyridine ligands: Good thermal stability toward ethylene polymerization

Vanadium complexes with unsymmetric bulky ligands 2-[1-(2,6-dibenzhydryl-4-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridine (V1-V3) and symmetrical bulky ligand 2,6-bis(1-(2,6-dibenzhydryl-4-methylphenylimino)ethyl)pyridine (V4) were prepared and thoroughly characterized. Single crystals of V1 and V4 were further tested with X-ray single crystal diffraction to prove the molecular structures, and a distorted triangular biconical geometry was adopted around vanadium centers of V1 and V4. These vanadium complexes bearing bulky ligands displayed moderate to high catalytic activity (up to 24.0 × 106 g molV-1 h−1) toward ethylene polymerization when ethylaluminum sesquichloride was employed as a cocatalyst, affording moderate to ultrahigh molecular weight polyethylenes (18.7 × 104 to 176.9 × 104 g/mol). Compared with the classical bis(imino)pyridine vanadium complex VR, complex V3 demonstrated a long lifetime as well as excellent thermal stability. Furthermore, polyethylenes derived from complexes V1-V4 had significantly higher molecular weights at high temperatures.

Anion-Driven Circularly Polarized Luminescence Inversion of Unsymmetrical Europium(III) Complexes for Target Identifiable Sensing.

Anion-responsive sign inversion of circularly polarized luminescence (CPL) was successfully achieved by N3O6-type nona-coordinated europium(III) (Eu3+) complexes [(R)-1 and (S)-1] composed of a less-hindered unsymmetrical N3-tridentate ligand (a chiral bis(oxazoline) ligand) and three O2-chelating (β-diketonate) ligands. Here, (R)-1 exhibited a positive CPL signal (IL – IR > 0) at the 5D0 → 7F1 transition of Eu3+, which can be changed to a negative sign (i.e., IL – IR > 0 → IL – IR < 0) by the coordination of trifluoroacetic anions (CF3COO–) to the Eu3+ center. However, (R)-1 preserved the original positive CPL signal (i.e., IL – IR > 0 → IL – IR > 0) in the presence of a wide range of competing anions (Cl–, Br–, I–, BF4–, ClO4–, ReO4–, PF6–, OTf–, and SbF6–). Thus, (R)-1 acts as a smart target identifiable probe, where the CPL measurement (IL – IR) can distinguish the signals from the competing anions (i.e., IL – IR < 0 vs IL – IR > 0) and eliminate the background emission (i.e., IL – IR = 0) from the background emitter (achiral luminescent compounds). The presented approach is also promising in terms of bio-inspired optical methodology because it enables nature’s developed chiral sensitivity to use circularly polarized light for object identification (i.e., IL – IR = 0 vs | IL – IR | > 0).

Solubility measurements and thermodynamic modelling of organoaluminum supported by unsymmetrical β-diketimine ligand

Organoaluminum supported by unsymmetrical β-diketimine ligands had special spatial and electronic effects. They were widely used in organic transformation, medicinal chemistry, and catalysis. Surveys the solubility of LH (1) and LAliBu2(2) in four pure solvents by the static analysis. The solubility data were correlated by seven thermodynamic models. All models demonstrated excellent fitting effect (absolute relative deviation (ARD) < 3 %, root mean square deviation (RMSD) < 0.01 %). For LAliBu2(2), Hirshfeld surface analysis was used to visualize the intermolecular interactions, and the simulation result showed that H···H contacts dominated major contact interactions. Further, the apparent thermodynamic functions were derived. It showed that, under the experimental conditions, the dissolution process of LH (1) and LAliBu2(2) was endothermic and entropy-driven. The results of the experiment have important implications for catalytic reactions and purification operations and the design of LH (1) and LAliBu2(2) in industrial production.

Synthesis and characterization of Ni(0) complexes supported by an unsymmetric C,N ligand

Over the past decade, N-heterocyclic carbene (NHC), bipyridine (bpy), and pyridine oxazoline (PyOx) ligands have been increasingly applied in nickel catalysis, where the combination of a low-oxidation-state 3d metal and an electron-rich ligand can enable otherwise challenging bond activations. Herein we report the synthesis and characterization of two Ni(0) complexes supported by an alternative, bidentate, C,N ligand, hIMesPy (“half-IMes-pyridine” or 1-(2,4,6-trimethylphenyl)-3-(2-pyridinyl)-imidazol-2-ylidene). The unsymmetric ligand combines the strong σ-donating properties of an NHC with the π-accepting properties of pyridine to afford homoleptic [Ni(hIMesPy)2] and heteroleptic [Ni(cod)(hIMesPy)] complexes. Characterization through the combination of single-crystal X-ray diffraction analysis and NMR spectroscopy, as well as reactivity studies demonstrating reversible interconversion between the two species, provide a strong basis for future applications to overcome reactivity challenges.

Chromium Catalysts Based on Unsymmetrical PNP Ligands for Selective Ethylene Tri-/Tetramerization: Effect of Electron-Withdrawing/Donating Substituents on Catalytic Performance

The in situ formation and activation of Cr(III) catalysts based on unsymmetrical PNP ligands yield efficient catalytic systems for selective ethylene tri-/tetramerization. The electronic nature (electron-withdrawing or electron-donating) and position (para or meta) of the substituents over the phenyl rings of the PNP, the nature of cocatalyst (DMAO/AlEt3 and MMAO-3A), and reaction conditions have been observed to have a marked impact on catalytic performance, particularly catalytic activity. Ligand L2, bearing 4-(trifluoromethyl)phenyl substituents, yielded 33.6 kg(product).g(Cr)−1·h−1 catalytic activity with 57.7% C8 selectivity under optimal conditions. Ligand L4, having para-tolyl substituents, yielded 43.3 kg(product).g(Cr)−1·h−1 with 59.0% C8 selectivity under optimum conditions. Changing the positions of both the electron-withdrawing and electron-donating substituents from para to meta over the phenyls of the PNP may lead to both catalytic systems exhibiting poor performance.

Differential study on the transition from a new polyhalogen-substituted unsymmetric salamo-based ligand to its Cu(II) and Co(II) complexes

Two structurally different Cu(II) and Co(II) complexes, [Cu(L)] (1) and [Co2(L)2]⋅2CH3OH (2), constructed from a new polyhalogen-substituted unsymmetric salamo-based ligand (H2L, 4-chloro-4′-bromo-6-bromo-6′-tert-butyl-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol) were synthesized by wet-chemical methods. Complexes 1 and 2 were characterized through elemental analyses, IR and UV-vis spectroscopies and single crystal X-ray crystallography. In addition, the differences of the structures, electronic absorption characteristics and fluorescence property transitions from the ligand to complexes 1 and 2 were studied. The largest difference is that the ligand H2L can react with M(OAc)2 (M = Cu(II) and Co(II)) to give two complexes with distinct structures and behaviors. There are two chemically identical but crystallographically independent structural units (molecules A and B) in 1. Moreover, each Cu(II) ion (Cu1 or Cu2) is four-coordinate and possesses a square planar geometry, but both Co(II) ions of 2 are bridged by phenoxide ions and possess five-coordinate trigonal bipyramidal configurations. At the same time, Hirshfeld surface analyses showed there are short-range interaction features from the ligand to complexes 1 and 2, the O···H/H···O interactions of the ligand are significantly stronger than those of 1 and 2.

Coordination Chemistry, Antibacterial Screening, and In Silico ADME Study of Mononuclear NiII and CuII Complexes of Asymmetric Schiff Base of Streptomycin and Aniline

Two novel metal complexes, that is, Ni (StmAn)2(4) and Cu (StmAn)2(5), were synthesized from unsymmetrical Schiff base ligand StmAn (3). The ligand was prepared by refluxing streptomycin (2) and aniline (1). They were characterized by elemental microanalysis, conductivity measurements, and spectroscopic techniques such as 1H NMR, FT-IR, ESI-mass, and electronic absorption spectral study. Interestingly, the study revealed metal coordination through azomethine nitrogen and N-atom of NH-CH3 of N-methyl-L-glucosamine unit of streptomycin. The electronic absorption spectral study supported an octahedral geometry for complex 4 and a tetrahedral geometry for complex 5. Particle size calculation by Scherrer’s formula indicated their nanocrystalline nature. The geometry optimization of the complexes was achieved by running an MM2 job in Gaussian supported Cs-ChemOffice ultra-12.0.1 and ArgusLab 4.0.1 version software. Based on SwissADME predictions, a theoretical drug profile was generated by analyzing absorption, distribution, metabolism, excretion, and toxicity (ADMET) scores of the compounds. They were screened for in vitro antibacterial activity study against four clinical pathogens such as E. coli, S. pneumoniae, P. vulgaris, and S. aureus. Minimum inhibitory concentration (MIC) study demonstrated greater inhibitory potency of complex (4) (0.024 g/L) for S. aureus relative to ligand (3) and complex (5). Studies show that metal complexes are more toxic to bacteria.

A Ni(II) chetale of an unsymmetrical N2O3 donor ligand and its use as flexidentate metalloligand to synthesise heterometallic Ni(II)-Mn(II) complexes: Recurrent CH⋯π and π-stacking motifs in the structures

An attempt to synthesis complexes of a N2O3 donor unsymmetrical Schiff base ligand, obtained from the condensation of 2,2-dimethyl-1,3-propanediamine with o-hydroxyacetophenone and o-vanillin via modified Edler's method yielded a mononuclear Ni(II) complex, [NiL]·1.5H2O·0.5CH3OH (1), where H2L = N-(α-methylsalicylidene)-N′-(3-methoxysalicylidene)-2,2-dimethyl-1,3-propanediamine. Three heterometallic Ni(II)-Mn(II) complexes, [(NiL)2Mn(H2O)2](ClO4)2·2H2O (2), [(NiL)MnCl2] (3) and [(NiL)Mn(NCS)2(H2O)]·[NiL] (4), have been isolated upon reaction of complex 1 with Mn(II) ions in presence respective co-anions, of which two are discrete complexes while third is a co-crystal. Single crystal X-ray crystallography revealed that Ni(II) centre is four coordinated in square planar environment in all complexes, whereas the geometry of Mn(II) centre is distorted octahedral in complexes 2 and 4, and distorted trigonal bipyramidal in 3. Structural differences have been rationalized by density functional theory (DFT) calculations. All the complexes exhibit recurrent π-stacking and CH⋯π motifs in solid state which have been characterized by molecular electrostatic potential (MEP) surface calculations and non-covalent interaction plot.

Design, Synthesis, Pharmacological Evaluation and DFT Investigation of New Bioactive Unsymmetrical Bi-Functional Ligand

Compounds with more than one bioactive motif become of great interest. In this regard, a new tridentate 1,2-unsymmetrical ligand consists of flexible and rigid bioactive arms spaced by benzene ring in an ortho position designed to form a bifunctional molecule. The 2-((3-(pyridin-2-yl)-1H-pyrazol-1-yl)methyl)benzonitrile (PPMB) synthesized under phase transfer reaction and characterized using 1H-NMR and mass spectroscopy and studied as potent kinase inhibitors. Theoretically, the molecule structure was investigated at the B3LYP/6-311++G(d,p) level of theory in the gas phase and revealed that all bond lengths and bond angles within the accepted limit. The frontier molecular orbitals (FMO) energies (HOMO and LUMO), energy gap, dipole moment, chemical softness and chemical hardness were calculated. Pharmacologically, the ligand activity was investigated in silico using SWISS ADME. Furthermore, the compound was docked into the transforming growth factor (TGF) beta type I receptor kinase active site to evaluate the ability of ligand as a kinase inhibitor.&#x0D; Keywords: DFT, pyrazolyl-pyridine, physiochemical, properties molecular docking, bioactive molecules, unsymmetrical ligands

Syntheses, crystal structures, theoretical studies, and anticancer properties of an unsymmetrical schiff base ligand N-2-(6-methylpyridyl)-2-hydroxy-1-naphthaldimine and its Ni(II) complex

In this work, syntheses of Schiff-base ligand, N-2-(6-methylpyridyl)-2-hydroxy-1-naphthaldimine (1) and its hitherto unknown chelate with a Ni(II) salt, bis[N-2-(6-methylpyridyl)-2-oxo-1-naphthaldimnato-k3N^N^O] nickel(II) (2) have been reported and characterized by spectral techniques (IR, 1H NMR, Mass). Solid state structures and non-covalent interactions persisting in 1 and 2 are studied by Density Functional Theory (DFT) optimizations and Hirshfeld Surface (HS) analysis. X-ray diffraction (XRD) study shows zwitter ionic keto-amine tautomer form of planar Schiff base 1 that exists as dimer formed by C13 ̶ H13A···O1i [(i) -x+1, -y, -z+1] hydrogen bonds and distorted octahedral geometry around Ni+2 center in chelate 2, where overall crystal structure stability may be attributed to weak C ̶ H···π, π···π stacking, van der Waals interactions, and C ̶ H···O type intermolecular hydrogen bonds. The HS study and 2D Finger Print (FP) plots corroborate well with XRD data and show prominent O···H/H···O spikes (2.2 Å < de+di < 2.3 Å) and C···H/H···C (2.5 Å < de+di < 2.6 Å) spikes that arise from C ̶ H···O type H-bonds and C ̶ H···π interactions respectively, along with significant C···C interactions (de+di ∼ 3.3 Å) due to π···π stacking (2). The anticancer activity has been investigated by using cytotoxicity measure (MTT assay), apoptosis assay, quantitative polymerase chain reaction (qPCR), and colony formation assays. The Ni(II) metal complex demonstrates dose-dependent cytotoxicity in vitro, killing A549 lung cancer cells via an apoptotic pathway.

Spectroscopic investigation, molecular structure, catalytic activity with computational studies of a novel Pd(II) complex incorporating unsymmetrical tetradentate Schiff base ligand

The treatment of an unsymmetrical tetradentate Schiff base ligand with Pd(OAc)2 salt yields novel palladium(II) Schiff base complex. The generated palladium(II) complex was characterized using elemental analysis (CHN) and different spectroscopic methods such as FT-IR and 1H NMR. Single crystal X-ray diffraction (SC-XRD) investigation has also been used to examine the crystal structure of the palladium complex. It is revealed from the SC-XRD study that the palladium ion in the complex is tetra-coordinated, inhabited by ONNO donor sites of the chelated ligand in a distorted square planar manner. The non-covalent interactions were explored by Hirshfeld surface analysis. The theoretical parameters calculated by DFT using the B3LYP/Def2-TZVP level of theory revealed that the theoretical conclusions matched the actual findings. For different aryl halides, the palladium(II) complex has exhibited excellent efficiency in the Suzuki-Miyaura cross-coupling reactions (SMCR), yielding biaryls in good to high yield.