Ligand HL Research Articles

3-Phenoxybenzaldehyde and Glycine-Derived Schiff base M(II) Complexes: Synthesis, molecular Modeling, spectroscopic Exploration, and antimicrobial evaluation

This study synthesized a novel bidentate Schiff base known as 2-((3-phenoxybenzylidene)amino)acetic acid (HL) derived from glycine and 3-phenoxy benzaldehyde and its M(II) complexes (M = Co2+, Cu2+, Ni2+ & Zn2+) was prepared by combining the Schiff base (HL) and the metal acetates in a 1:2 ratio. The molecular structure of the Schiff base was confirmed using CHN analysis, mass, FT-IR, UV–Vis, 1H NMR and 13C NMR spectra. The prepared complexes were analyzed using CHN analysis, mass, FT-IR, UV–Vis, molar conductivity studies, magnetic susceptibility studies, and ESR for Cu(II) complexes. Based on the analysis, square planar geometry is suggested for the Cu(II) & Ni(II) complexes and tetrahedral geometry for Co(II) and Zn(II) complexes. A preliminary in vitro antimicrobial investigation of the synthesized ligand and its related complexes has been performed. The M(II) complexes showed more potent antimicrobial activity than its Schiff base; in particular, the Cu(II) complex illustrated notable inhibitory effects. Molecular docking studies were conducted against CDK2 (PDB ID: 1B39), α-amylase (PDB ID: 4W93), and α-glucosidase (PDB ID: 3TOP). The Ligand HL demonstrated AutoDock/MM-GBSA binding energy values of −5.9 /-104 kcal mol−1 (CDK2), −6.6 /-134 kcal mol−1 (α-amylase), and −7.4/ −174.84 kcal mol−1 (α-glucosidase). The complexes exhibited MM-GBSA binding energy values within the range of −198.20 to −198.72 kcal mol−1 (CDK2), −250.00 to −250.02 kcal mol−1 (α-amylase), and −279.51 to −283.84 kcal mol−1 (α-glucosidase). The molecular docking results shed light on the potential of ligand HL and its metal complexes as promising candidates for further exploration in therapeutics, particularly in targeting CDK2 inhibition (anticancer) and α-amylase and α-glucosidase inhibition (antidiabetic).

DNA interaction, biological, and structural identification studies of bivalent nano‐sized Nickel, Palladium, and Platinum chelates of 2‐(((Z)‐6‐chloro‐3‐((E)‐([2‐hydroxyphenyl]imino)methyl)‐4H‐chromen‐4‐ylidene)amino)phenol Schiff base ligand

New nano‐sized Ni(II), Pd(II), and Pt(II) Schiff base chelates of 2‐(((Z)‐6‐chloro‐3‐((E)‐([2‐hydroxyphenyl]imino)methyl)‐4H‐chromen‐4‐ylidene)amino)phenol were designed and manufactured. The structural characterization of these isolated compounds was accomplished through spectral measurements, thermal and elemental analyses, and magnetic moment and conductivity determinations. The nano‐sized metal(II) complexes molar conductance indicated that they exhibited non‐electrolytic behavior. The UV–Vis spectral data and magnetic moment provided evidence for producing octahedral geometries in the nano‐sized complexes of Ni(II), Pd(II), and Pt(II). Metal chelates' thermal characteristics and decomposition kinetics were examined through Coats‐Redfern technique. The kinetic aspects, including pre‐exponential factor (A), the entropy of activation (ΔS), and activation energy (E) were enumerated. The X‐ray diffraction (XRD) calculations results of the trivalent metal complexes showed that sharp and intense diffraction peaks signify their crystalline properties with nanoscale particle size, and another proof was obtained from the images of SEM, TEM, EDX, and AFM also homogeneous distribution over the complex surface was confirmed. Molecular modeling techniques were adopted to optimize the metal complexes geometry. The viscosity and UV–Vis absorption determinations were utilized to assess the calf thymus DNA (CT‐DNA) interaction with the nano‐sized metal(II) chelates. The acquired data revealed that the complexes exhibit a non‐intercalative or incomplete binding pattern when interacting with DNA. The calculated DNA‐complexes binding constants are 3.93 ± 0.02 × 10,4 1.67 ± 0.3 × 105 and 2.88 ± 0.03 × 105 M−1, for nano‐sized Ni(II), Pd(II) and Pt(II) Schiff base chelates, successively. Both Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Bacillus subtilis and Streptococcus pneumoniae) micro‐organisms were tested against H2L Schiff base ligand and its nano‐sized metal(II) complexes. Candida albicans and Aspergillus fumigatus were tested for antifungal activity, revealing that most complexes had activity lower than H2L ligand, while the complex of Ni(II) exhibited no discernible antifungal activities. Furthermore, the manufactured complexes underwent testing for their in‐vitro anticancer and antibacterial effectiveness. Furthermore, the complexes antioxidant activity was appraised through DPPH and ABTS inhibition tests, revealing distinct scavenging abilities on DPPH radicals. The complexes were ordered according to their scavenging capacity as follows: Ni(II) complex > Pd(II) complex > Pt(II) complex. Finally, the study of cell cycle arrest by the Ni(II), Pd(II), and Pt(II) complexes on HEPG2 has also been performed through flow cell cytometry.

Co(II) Metal-Organic Complex: Fluorescence Performances and Loaded With Drug Vitamin B2 Hydrogels Against Recurrent Oral Ulcers.

A new coordination polymer (CP) based on Co(II), namely, {[Co3(L)2(4,4'-bipy)(DMA)2]·H2O}n(1) has been synthesized after reacting Co(NO3)2·6H2O with H3L ligand in the existence of N-donor ligand 4,4'-bipyridine (4,4'-bipy), via utilizing a flexible tricarboxylic acid ligand 5-((formic acid-3-sulfur)methyl)isophthalic acid (H3L) with -S-CH2- joint. Additionally, the excellent blue fluorescence properties of CP 1 were confirmed through fluorescence spectroscopy compared to the original ligand. Using natural polysaccharide hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, HA/CMCS hydrogel was prepared by chemical synthesis method. Taking vitamin B2 as the drug model, we designed and synthesized gels loaded with vitamin B2 metal framework and evaluated their efficacy in the treatment of recurrent oral ulcer.

{GdIII7} and {GdIII14} Cluster Formation Based on a Rhodamine 6G Ligand with a Magnetocaloric Effect.

Heptanuclear {GdIII7} (complex 1) and tetradecanuclear {GdIII14} (complex 2) were synthesized using the rhodamine 6G ligand HL (rhodamine 6G salicylaldehyde hydrazone) and characterized. Complex 1 has a rare disc-shaped structure, where the central Gd ion is connected to the six peripheral GdIII ions via CH3O-/μ3-OH- bridges. Complex 2 has an unexpected three-layer double sandwich structure with a rare μ6-O2- ion in the center of the cluster. Magnetic studies revealed that complex 1 exhibits a magnetic entropy change of 17.4 J kg-1 K-1 at 3 K and 5 T. On the other hand, complex 2 shows a higher magnetic entropy change of 22.3 J kg-1 K-1 at 2 K and 5 T.

Designing of novel nano-sized coordination compounds based on Spinacia oleracea extract: Synthesis, structural characterization, molecular docking, computational calculations, and biomedical applications

A novel series of nano-sized metal chelates of 1-((E)-(2-mercaptophenylimino)methyl)naphthalen-2-ol (H2L) Azo-methine ligand with Fe(III), Ni(II) and Ag(II) were prepared and investigated for antitumor activities. The structures of all the synthesized compounds have been analyzed using various physicochemical techniques. The results showed a distorted square-planar geometry for Ni2L2 and AgL, whereas the geometry around the FeL complex is octahedral. The nano-sized Fe and Ag complexes were prepared in an easy, rapid andeco-friendly way using Spinacia oleracea (SO) extract in EtOH. X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV.Vis. spectra were used to assess the structural characteristics and particle size of the newly produced nano-sized Fe and Ag complexes. Furthermore, from TGA, we investigated the impact of heat on the particle size of newly prepared compounds. The geometry optimization of the prepared complexes and various quantum chemical parameters were computed by Gaussian 09 softwares. The results showed that all of the metal complexes studied are more stable than the free ligand H2L, with the Ni2L2 complex being the most stable. All micro- and nano-complexes were tested for in vitro anticancer activities, and the results revealed inhibition of cancer cell activity, although the smaller size is better than the larger size. The liver cancer and COVID‑19 were screened using molecular docking to determine the possible binding energy of inhibitors.

Chiral Au(III) chelates exhibit unique NCI-60 cytotoxicity profiles and interactions with human serum albumin.

Au(III) bis(pyrrolide-imine) chelates are emerging as a class of versatile, efficacious metallodrug candidates. Here, we synthesised two enantiopure chiral ligands H2L1 and H2L2 (tetradentate cyclohexane-1,2-diamine-bridged bis(pyrrole-imine) derivatives). Metallation of the ligands with Au(III) afforded the chiral cationic complexes AuL1 and AuL2. The in vitro cytotoxicities of AuL1 and AuL2 determined in the NCI-60 single-dose drug screen were 56.5% and 89.1%, respectively. AuL1 was subsequently selected for a five-dose NCI-60 screen, attaining GI50, IC50, and LC50 values of 4.7, 9.3 and 39.8 μM, respectively. Hierarchical cluster analysis of the NCI-60 data indicated that the profile for AuL1 was similar to that of vinblastine sulfate, a microtubule-targeting vinca alkaloid. Reactions of AuL1 with glutathione (GSH) in vitro confirmed its susceptibility to reduction, Au(III) → Au(I), by intracellular thiols. Because human serum albumin (HSA) is responsible for transporting clinically deployed and investigational drugs, we studied the uptake of AuL1 and AuL2 by HSA to delineate how chirality impacts their protein-binding affinity. Steady-state fluorescence quenching data acquired on the native protein and data from site-specific probes showed that the compounds bind at sites close enough to Trp-214 (subdomain IIA) of HSA to quench the fluorophore. The bimolecular quenching rate constants, Kq, were ca. 102 times higher than the maximum diffusion-controlled collision constant of a biomolecule in water (1010 M-1 s-1), confirming that static fluorescence quenching was the dominant mechanism. The Stern-Volmer constants, KSV, were ∼104 M-1 at 37 °C, while the affinity constants, Ka (37 °C), measured ∼2.1 × 104 M-1 (AuL1) and ∼1.2 × 104 M-1 (AuL2) for enthalpy-driven ligand uptake targeting Sudlow's site I. Although far- and near-UV CD spectroscopy indicated that both complexes minimally perturb the secondary and tertiary structure of HSA, substantial shifts in the CD spectra were recorded for both protein-bound ligands. This study highlights the role of chirality in determining the cytotoxicity profiles and protein binding behaviour of enantiomeric Au(III) chelates.

Structurally diverse zinc(II) complexes containing tripodal tetradentate phenoxido-amines with promising antiproliferative effects.

Structurally diverse zinc(II) complexes with tripodal tetradentate phenolic-amines of variable substituents in the phenol and amine moieties were synthesized and thoroughly characterized. The two dinuclear [Zn2(L1)2](ClO4)2·MeOH (1), [Zn2(L2)2](ClO4)2 (2), and four mononuclear [Zn(L3)(H2O)]·MeOH (3), [Zn(L4)] (4), [Zn(L5)] (5) and [Zn(L6)] (6) complexes revealed distorted octahedral, trigonal-bipyramidal or tetrahedral geometries. The free HL1 and H2L3-6 ligands, and complexes 1-6 were evaluated for in vitro cytotoxicity against human cancer cell lines (A2780, A2780R, PC-3 and 22Rv1) and normal healthy MRC-5 cells. Overall results revealed high-to-moderate cytotoxicity (with the best IC50 values for complex 6 ranging from 2.4 to 4.5 μM), which is however, significantly higher than that of the reference drug cisplatin. The moderately active complexes 1-4 showed considerable selectivity on A2780 cells (IC50 ≈ 16.3-19.5 μM) over MRC-5 ones (with IC50 >50 μM for 1, 2 and 4, and with IC50 >25 μM for 3). The complexes 1, 2, and 6 and the ligand H2L6 were chosen for subsequent deeper biological evaluations. Their time-resolved cellular uptake and other cellular effects in A2780 cells were studied, such as cell cycle profile, intracellular ROS production, induction of apoptosis and activation of caspases 3/7. Complexes 1 and 2 caused significant G0/G1 cell cycle arrest in A2780 cells and antioxidant effects at normal conditions. They showed only limited effects on cellular processes connected with cytotoxicity, i.e. induction of apoptosis, depletion of mitochondrial membrane potential, and autophagy. These findings can be at least partly attributed to the low ability of the complexes to enter the A2780 cells and the depression of metabolic activity of the target cancer cells.

Ni(II) and Pd(II) complexes of a new redox-active pentadentate azo-appended 2-aminophenol ligand: Pd(II)-assisted intraligand cyclization forms a phenoxazinyl ring.

Square planar complexes of Ni(II) and Pd(II) of a new redox-active pentadentate azo-appended 2-aminophenol ligand (H4L = N,N'-bis(2-hydroxy-3,5-di-tert-butylphenyl)-2,2'-diamino-ortho-azobenzene) in three accessible redox levels [amidophenolate(2-), semiquinonate(1-) π radical, and quinone(0)] were synthesized. The coordinated HL(3-) ligand provides four donor sites [two N(iminophenolates), an N'(azo), and an O(phenolate)], while the phenolic OH group remains free in the three complexes. Cyclic voltammetry on complex [Ni(L)] 1 and its corresponding Pd(II) analogue [Pd(L)] 2 in CH2Cl2 displayed three redox responses (two oxidative at E1/2 = 0.06 V and Epa (anodic peak potential) = 0.80 V and one reductive at -0.77 V for 1 and at E1/2 = 0.08 V and Epa = 0.85 V and at -0.74 V for 2vs. Fc+/Fc). The chemical oxidation of 1 with AgSbF6 afforded [Ni(L)]SbF6·2CH2Cl2 (3·2CH2Cl2). Complex [Pd(L*)] 4, which is coordinated by a phenoxazinyl derivative of L(4-), was obtained via intraligand cyclization in the parent complex 2 under basic oxidizing conditions. The molecular structures of 1, 2, 3·2CH2Cl2 and 4 were elucidated through X-ray crystallography at 100 K. Characterization using 1H NMR, X-band EPR, and UV-VIS-NIR spectroscopy established that the complexes have [NiII{(LISQ)˙2-}] 1, [PdII{(LISQ)˙2-}] 2, [NiII{(LIBQ)-}]SbF6/1+SbF6-(3), and [PdII{(L*AP)˙2-}] 4 electronic states. Complexes 1, 2, and 4 possess paramagnetic St (total spin) = 1/2 ground-state, whereas 3 is diamagnetic (St = 0). Density functional theory (DFT) electronic structural calculations at the B3LYP level rationalized the observed experimental results. Time-dependent (TD)-DFT calculations allowed us to identify the nature of the observed absorption spectra.

From field-induced to zero-field SMMs associated with open/closed structures of bis(ZnDy) tetranuclear complexes: a combined magnetic, theoretical and optical study.

We have prepared a bis(compartmental) Mannich base ligand H4L (1,4,8,11-tetraaza-1,4,8,11-tetrakis(2-hydroxy-3-methoxy-5-methylbenzyl)cyclotetradecane) specifically designed to obtain bis(TMIILnIII) tetranuclear complexes (TM = transition metal). In this regard, we have succeeded in obtaining three new complexes of the formula [Zn2(μ-L)(μ-OAc)Dy2(NO3)2]·[Zn2(μ-L)(μ-OAc)Dy2(NO3)(OAc)]·4CHCl3·2MeOH (1) and [TM2(μ-H2L)2(μ-succinate)Ln2(NO3)2] (NO3)2·2H2O·6MeOH (TMII = Zn, LnIII = Dy (2); TMII = Co, LnIII = Dy (3)). Compound 1 contains two different bis(ZnDy) tetranuclear molecules that cocrystallize in the structure, in which acetato bridging ligands connect the ZnII and DyIII ions within each ZnDy subunit. This compound does not exhibit slow magnetic relaxation at zero field, but it is activated in the presence of an applied dc magnetic field and/or by Dy/Y magnetic dilution, showing two relaxation processes corresponding to each of the two different bis(ZnDy) units found in the structure. As revealed by the theoretical calculations, magnetic relaxation in 1 is single-ion in origin and takes place through the first excited state of each DyIII ion. When using the succinato dicarboxylate bridging ligand instead of acetate, compounds 2 and 3 were serendipitously formed, which have a closed structure with the succinate anion bridging two ZnDy subunits belonging to two different ligands. It should be noted that only compound 2 exhibits slow relaxation of magnetization in the absence of an external magnetic field. According to experimental and theoretical data, 2 relaxes through the second excited Kramers doublet (Ueff = 342 K). In contrast, 3 displays field-induced SMM behaviour (Ueff = 203 K). However, the Co/Zn diluted version of this compound 3Zn shows slow relaxation at zero field (Ueff = 347 K). Ab initio theoretical calculations clearly show that the weak ferromagnetic coupling between CoII and DyIII ions is at the origin of the lack of slow relaxation of this compound at zero field. Compound 2 and its diluted analogues 2Y and 3Zn show hysteresis loops at very low temperature, thus confirming their SMM behaviour. Finally, compounds 1 and 2 show DyIII based emission even at room temperature that, in the case of 2, allows us to extract the splitting of the ground 6H15/2 term, which matches reasonably well with theoretical calculations.

Binucleating Jäger-type {(N2O2)2}4- ligands: magnetic and electronic interactions of Fe(II), Ni(II) and Cu(II) across an in-plane TTF-bridge.

The simultaneous presence of different electrophores provides an interesting playground for responsive materials. Herein, we present the incorporation of a twice-reversibly oxidizable tetrathiafulvalene (TTF) unit into a binucleating ligand, bridging two metal centers in a fully conjugated plane. A two-step synthesis scheme gave the D2h symmetric Schiff base-like ligand H4L in moderate yields from which the corresponding copper(II) [Cu2L], nickel(II) [Ni2L], [Ni2L(py)4] and iron(II) complexes [Fe2L(py)4], [Fe2L(dmap)4] and [Fe2L(bpee)2]·1 Tol could be obtained. Characterization was performed through 1H-NMR, IR, UV-vis and 57Fe-Mössbauer spectroscopy, SQUID magnetometry and cyclic voltammetry, supported by density functional theory (DFT) calculations. Single crystal X-ray analysis of [Ni2L(py)4] revealed six-coordinate paramagnetic centers, whereas [Ni2L] underwent gradual coordination induced spin state switching (CISSS) in solution. The magnetic independence of both metal centers is echoed by close-to-ideal Curie-plots of the [Cu2L] system and the gradual spin crossover of all iron(II) compounds. By contrast, cyclic voltammetry measurements in solution indicated oxidation-dependent TTF-metal interactions, as well as metal-metal interactions. The reversible TTF-borne events in H4L and [Ni2L] are overlaid with metal-borne events in the case of [Fe2L(py)4], as is corroborated by an analysis of the frontier orbital landscapes and through diagnostic spectral features upon chemical oxidation.

Effect of ligand substituents on the reactivity pathways of copper(II) complexes towards electrocatalytic water oxidation.

The electrocatalytic water oxidation activity of three copper(II) complexes [Cu(L1H)(L1)](ClO4) (1), [Cu(L2H)(L2)(H2O)](ClO4) (2) and [Cu(L3H)(L2)](ClO4) (3) with aryl oxime ligands L1H, L2H and L3H [L1H = 1-(pyridin-2-yl)methanone oxime, L2H = 1-(pyridin-2-yl)ethanone oxime and L3H = 1-(pyridin-2-yl)propanone oxime] was investigated. All the three ligands have in common a pyridyl group attached to the carbon centre of the oxime moiety and differ in the second substituent attached to the carbon centre. Electrochemical investigation of the catalytic activity of complexes 1, 2 and 3 shows that the nature of the substituent attached to the carbon centre has an influence on the catalytic pathway and overall catalytic activity of these complexes.

Pillared lanthanide metal organic frameworks with sinusoidal channels formed from bent mixed-donor phenanthroline based ligands of different length.

Five new lanthanide MOFs were prepared by solvothermal synthesis to investigate the effect of ligand and pillar length using the unsymmetrical mixed-donor ligands L1H (4'-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-[1,1'-biphenyl]-3-carboxylic acid) and L2H (3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzoic acid)...

Synthesis and catalytic activity of heterobimetallic Au/M (M = RhIII, IrIII) complexes with ditopic mono- and triphosphane ligands.

A series of heterobimetallic complexes Au/M (M = RhIII, IrIII) were prepared on the basis of two ditopic ligands: a monophosphane ligand L1H and a triphosphane ligand L2H. The complexes were fully characterised, including single-crystal X-ray diffraction studies. Catalytic activity of cationic L1/AuI/IrIII and L2/AuI/IrIII bis(trifluoromethane)sulfonimide was analysed through their capacity to induce allenyl ether rearrangement and cycloisomerisation of N-propargyl benzamide. While cationic L1/AuI/IrIII showed some ability to induce allenyl ether rearrangement, no conversion was observed for cationic L2/AuI/IrIII. Similarly, N-propargyl benzamide could undergo cycloisomerisation in the presence of cationic L1/AuI/IrIII, whereas cationic L2/AuI/IrIII was again inactive. These findings highlight how crucial the surroundings of the metal centre are to the catalytic activity. Catalytic activity is only possible when Au has a free coordination site; the gold complex becomes inactive when the tridentate ligand is present.

Six-coordinated nickel(II) complexes with benzothiadiazole Schiff-base ligands: synthesis, crystal structure, magnetic and HFEPR study.

Two new nickel(II) complexes, namely Ni(L1)2 (1) and Ni(L2)2·CH2Cl2(2) were obtained by reacting nickel(II) acetate tetrahydrate with the benzothiadiazole Schiff base ligands HL1 = 2-[4-(2,1,3-benzothiadiazole)imino]methyl-phenol or HL2 = 2-[(2,1,3-benzothiadiazol-4-ylimino)methyl]-6-methoxyphenol in the presence of Et3N. The tridentate NNO chelate ligands induce a distorted octahedral environment around the nickel(II) ions. Single crystal X-ray diffraction analysis reveals elongated Ni-N bonds with the nitrogen atom of the benzothiadiazole ring in both complexes. Intermolecular hydrogen bonds and π-π stacking interactions create two-dimensional and three-dimensional supramolecular arrays, respectively, for complexes 1 and 2. Magnetic susceptibility and high-field electron paramagnetic resonance measurements show the presence of significant magnetic anisotropy, with an axial distortion parameter D of -8--10 cm-1.

Magnetic properties of a europium(III) complex - possible multiplet crossover.

A dinuclear complex [(H2O)Zn(LH)Eu(NO3)3] containing a hexadentate Schiff-base {N2O4}-donor ligand LH2- was prepared and characterized by X-ray structural analysis and IR, electronic and fluorescence spectroscopy. DC magnetic data show that upon heating the diamagnetic complex with the ground state Eu(III)-7F0 and Zn(II)-1S switches to paramagnetic species due to the population of 7FJ (J = 1 to 6) magnetic multiplets. The magnetic susceptibility increases from zero, passes through a maximum, and then decreases upon heating. This behaviour can be explained using a spin-orbit Hamiltonian with an axial distortion term. There is an alternative interpretation of the susceptibility data based on a two-level model similar to that used in the spin crossover theory.

Using eugenol scaffold to explore the explosive sensing properties of Cd(II)-based coordination polymers: experimental studies and real sample analysis.

Eugenol, the major constituent of clove oil, has been explored as an essential natural ingredient for ages owing to its versatile pharmacological properties. However, to date, the coordination chemistry of eugenol derivatives has not been much explored. In the present work, an eugenol-based Schiff base ligand (HL) was synthesized and structurally confirmed through ESI-MS, NMR, and FT-IR spectroscopy studies. Consequently, the N,O-donor chelating ligand HL was coordinated with Cd2+, in the presence of bridging pseudohalides (thiocyanate, SCN-, and dicyanamide, N(CN)2-) to synthesize two luminescent coordination polymers (CPs 1 and 2): [Cd2(L)2(X)2]n (where HL = 4-allyl-2-(((2-(benzylamino)ethyl) imino)methyl)-6-methoxyphenol and Xs are bridging pseudohalides, i.e., SCN- and N(CN)2-) on a Cd-eugenol scaffold. The CPs depicted structural diversity, bulk-phase purity, thermal stability, and the presence of interlayer supramolecular C-H⋯π interactions together with C-H⋯S (for CP 1) and C-H⋯N (for CP 2) interactions. The CPs further exemplified themselves as selective and sensitive 'turn-off' probes towards trinitrophenol (TNP) (quenching efficiency: 82.02% and 83.86% for 1 and 2) among a pool of hazardous nitroaromatic compounds (NACs). Accordingly, 1 and 2 exhibited an ultralow limit of detection (LOD) of 0.29 and 0.15 μM, with high quenching constants (KSV) of 5.91 × 104 and 17.60 × 104 M-1, respectively. In addition, TNP sensing events were evidenced to be recyclable and exhibited fast response (∼31 s, 1, and ∼40 s, 2), which increased its real-world viability. Vapor phase TNP sensing was also accomplished upon drop-casted CP films. Experimental investigations and theoretical DFT study confirmed the cooperative occurrence of RET-IFE-PET-collisional quenching and non-covalent π⋯π stacking as key factors involved in the TNP sensing performance. The competency of 1 and 2 in the detection of TNP from several complex environmental matrices (CEMs), viz. matchstick powder, river and sewage water, and soil specimens, was also established with good recovery (∼66-86% and ∼68-93% for 1 and 2, respectively) and high KSV values (3.90-11.39 × 104 and 6.17-18.79 × 104 M-1 for 1 and 2, respectively).

IMPACT OF METAL SALTS ON COORDINATION CHEMISTRY OF NICKEL(II) WITH A N3O DONOR SCHIFF BASE LIGAND: SYNTHESIS, STRUCTURES AND HERSHFIELD SURFACE ANALYSIS

The key findings and significance of this report is the synthesis and characterization of two mononuclear nickel(II) complexes, [Ni(L)(val)].0.5MeOH (1) and [Ni(HL)2](ClO4)2 (2) derived from a tetradentate Schiff base ligand HL and two different nickel(II) salts. These complexes were thoroughly characterized using techniques such as elemental analysis, IR spectroscopy, single crystal X-ray diffraction, and Hirshfeld surface analysis. The results revealed distinct coordination modes of the ligands in the complexes, leading to different non-covalent interactions and packing arrangements in their crystal structures. Specifically, complex 1 exhibited tetradentate coordination in addition to the bidentate o-vanillinate ligand, while complex 2 featured tridentate coordination with the zwitterionic form of the ligand. Hirshfeld surface analysis provided insights into the relative contributions of various intermolecular interactions, highlighting the significance of hydrogen bonding, tetrel bonding, and other non-covalent interactions in stabilizing the crystal structures. In general, this study contributes to the differences in structural integrity on slide variation in metal salts and the understanding in depth of various non covalent interactions using Hirshfeld surface analysis tool.

Solid state conversion of novel coordinated precursors to visible light active photocatalysts with enhanced photocatalytic activity

The new polydentate N'1,N'3‐bis((E)‐3‐oxopentan‐2‐ylidene)malonohidrazide chelating agent (H2L) and its coordinated complexes of Co2+, Cu2+, and Ni2+ were prepared and characterized by elemental analysis, molar conductance, and spectra (Fourier transform infrared [FT‐IR], ultraviolet–visible spectroscopy [UV–vis], and Fast‐Atom Bombardment Mass Spectrometry (FAB‐MS). Also, thermal and magnetic investigations were conducted. X‐ray single crystal of the H2L ligand revealed a triclinic structure with space group P‐1. In this study, we provide a one‐pot preparation approach for transition metal oxide nanoparticles (NPs) such as CuO, Co3O4, and NiO NPs. The methodology entails the thermal decomposition of coordinated metal precursors in a solid‐state environment, obviating the necessity for agitation and rinsing. The remarkable significance of this method lies in its ability to produce highly pure NPs without the requirement of washing, and it allows for systematic and efficient production. Herein, we propose a large‐scale, environmentally benign and renewable, transition metals oxide NPs such as CuO, Co3O4, and NiO using solid‐state thermal degradation of their coordinated precursors. The NPs are subjected to analysis employing a range of techniques, such as X‐ray powder diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), N2 sorpometry (BET), and UV–vis). The photocatalytic activities of the synthesized NPs were assessed using photodegradation of organic contaminants in wastewater.

New Pd(II) complexes containing hydrazinyl oxazolyl coumarin derivatives: synthesis, spectral characterization and anti-cancer studies

Abstract New palladium(II) complexes containing coumarin derivatives such as (E)-3(2-(2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinyl)oxazol-4-yl)-2H-chromen-2-one (HL 1 ), (E)-7-hydroxy-3(2-(2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinyl)oxazol-4-yl)-2H-chromen-2-one (HL 2 ) were successfully designed and synthesized from the reaction of K2[PdCl4] with ligands HL 1&2 with in Methanol medium. The ligands and complexes were characterized by various analytical and spectral techniques such as FT-IR, UV–Vis, 1H NMR and 13C NMR spectral techniques. From the spectral data we confirmed that the ligands neutrally coordinated with Pd(II) ion via their lactone oxygen, azomethine nitrogen and oxazolyl ring nitrogen atoms. The electrolytic nature of the complexes was confirmed by using conductivity experiments. Further anticancer activity of the compounds has examined with HeLa (human cervical cancer) cells along with the cisplatin as positive control and the obtained results revealed that the complexes possess significant anticancer activity and non-toxic towards HUVEC (human umbilical vein endothelial) cells.

Structural investigations of new tridentate-phenylacetohydrazide Schiff base metal chelates: X-ray diffraction, Hirshfeld surface analyses, DFT, antibacterial and molecular docking studies

The coordination complexes of a tridentate-phenylacetohydrazide Schiff base (2-hydroxybenzylidene-2-phenylacetohydrazide, HL) with metal ions, namely, iron(II), zinc(II), palladium (II), silver(I) and cadmium(II), were synthesized and investigated using various analytical and spectroscopic techniques. A single-crystal X-ray diffraction analysis was performed on the silver derivative. The HL ligand and Ag complex were also characterized via Hirshfeld surface analyses. Both X-ray and Hirshfeld surface analysis revealed intriguing structure and geometric characteristics, as well as remarkably intramolecular and intermolecular hydrogen bonding. All metal ions, with the exception of palladium one, bonded to two molecules of ligand without deprotonation of the hydroxyl moieties. In addition, 1H NMR studies of the diamagnetic complexes and X-ray analysis of the silver complex revealed the presence of the unprotonated OH. DFT-B3LYP calculations were used to determine the energy-minimized molecular geometric arrangements of the Pd(II), Ag(I), and Cd(II) derivatives. Quantum global reactivities of the complexes were also computed. Antibacterial and molecular docking studies of complexes were carried out to examine the potential applications of derivatives as therapeutic reagents. The Ag(I) complex showed the highest antibacterial inhibition towards the tested bacteria with zone diameter = 21.7, 21.0, 19.3 and 15.7 mm. Molecular docking analysis revealed that the complexes have high binding affinities against the selected receptors (PDB: 1BNA and 5AEP) and demonstrated different DNA binding potencies.