This work investigates the cytotoxic and antioxidant potential of newly synthesized azo-functionalized Schiff base ligands and their corresponding Pd(II) complexes. The ligands were obtained via condensation reactions between azo-aldehydes and 4-aminoantipyrine, and their structures, along with those of the metal complexes, were characterized using FT-IR, UV–Vis, and NMR spectroscopic techniques. In addition, the solid-state structures of ligands 4 and 5 were confirmed by single-crystal X-ray diffraction analysis. Furthermore, density functional theory (DFT) calculations were performed to investigate the optimized molecular geometries, frontier molecular orbitals, global reactivity parameters, nonlinear optical (NLO) properties and tautomeric forms of the synthesized ligands. The biological activities of the synthesized compounds were evaluated under in vitro conditions. Cytotoxicity studies against OUMS and HUVEC cell lines revealed that the biological activities of the Pd(II) complexes were dependent on the ligand framework. While complexes 7 and 8 did not show improved activity compared with the corresponding free ligands, complex 9 exhibited cytotoxic activity comparable to the most active ligand and cisplatin against OUMS cells. The IC50 values ranged from 49.65 to 277.9 μg/mL. Antioxidant activity was assessed spectrophotometrically using the MTS method. All compounds demonstrated measurable antioxidant activity, although their activities remained lower than that of ascorbic acid. These findings indicate that coordination of the aminoantipyrine-based azo-Schiff base ligands to Pd(II) significantly influences their biological behavior.

Two novel mononuclear copper(II) complexes, [Cu(H4N9-mpz)]Cl2·H2O (1) and [Cu(H4N9-mpz)](ClO4)2·2CH3OH (2), were synthesized for the first time utilizing the pyrazine-modulated long-chain pentapyridyltetraamine ligand, N2,N2′-(pyrazine-2,6-diyl)bis(N6-(pyridin-2-yl)pyridine-2,6-diamine) (H4N9-mpz). Both complexes were structurally characterized, and their in vitro cytotoxic activities were systematically evaluated. In each compound, the Cu(II) center is five-coordinate, adopting a slightly distorted trigonal bipyramidal geometry, with Addison distortion parameter τ values of 0.84 for complex (1) and 0.86 for complex (2). The H4N9-mpz ligand adopts an all-anti conformation, coordinating to the copper center as a pentadentate monohelical ligand. This trigonal bipyramidal coordination environment was further corroborated by electronic spectroscopy and the observation of "inverted-type" electron paramagnetic resonance (EPR) spectra. The cytotoxic effects of the free H4N9-mpz ligand and complexes 1 and 2 were evaluated against the DLD-1 and PC3 cancer cell lines, as well as the L929 healthy cell line, and compared with the reference drug cisplatin. Complex 2 exhibited superior antiproliferative activity compared to 1, yielding significantly lower IC50 values of 6.401 µM in DLD-1 cells and 2.956 µM in PC3 cells. However, toxicity profiles on healthy L929 cells revealed that complex 1 possesses a higher selectivity index than complex 2. Molecular docking simulations revealed distinct, target-dependent interaction profiles; the free ligand exhibited the highest predicted affinity toward Bcl-2, whereas the copper(II) complexes demonstrated more favorable docking scores against HSP90. These findings provide preliminary computational insights into potential ligand–protein interactions, prompting further experimental validation.

A new mixed-ligand copper(II) maleate complex, [Cu(H₂dpzpda)(mal)]·CH₄O, containing the neutral tridentate H₂dpzpda ligand and a bidentate maleate ligand (mal²⁻), was synthesized and comprehensively characterized by physicochemical methods. The molecular structure of the compound was determined by single-crystal X-ray diffraction analysis. It was shown that the Cu(II) ion is in a five-coordinate N3O2 environment formed by three nitrogen atoms of the ligand and two oxygen atoms of the maleate anion. The Cu–N bond lengths are 1.998(3) Å (Cu–N4), 2.028(3) Å (Cu–N1), and 2.074(3) Å (Cu–N6), while the Cu–O distances are 1.927(3) Å (Cu–O3) and 2.111(3) Å (Cu–O1), which are consistent with typical values for copper(II) complexes. The crystal structure is stabilized by a system of intermolecular hydrogen bonds, leading to the formation of a supramolecular organization. Single-crystal X-ray diffraction analysis revealed that the Cu(II) center is five-coordinate and adopts a distorted trigonal bipyramidal geometry, as indicated by the trigonality index (τ = 0.78). The EPR parameters (g⊥ > g∥ ≈ gₑ, where gₑ = 2.0023) are consistent with this coordination environment and support the localization of the unpaired electron in the dz² orbital.The synthesized copper(II) complex was characterized with particular emphasis on its electronic structure, intermolecular interactions, and biological targeting potential. DFT calculations revealed a HOMO–LUMO energy gap of 3.87 eV, indicating a balance between kinetic stability and chemical reactivity, with significant electrophilic character as supported by a global electrophilicity index of 1.84 eV. Hirshfeld surface analysis and fingerprint plots demonstrated that the crystal architecture is primarily stabilized by H···O (26.8%) and H···N (14.0%) hydrogen bonding, alongside localized but structurally significant π-π stacking interactions (enrichment ratio = 3.10). Molecular Electrostatic Potential (MEP) mapping further identified nucleophilic oxygen sites and electrophilic nitrogen regions, providing a spatial roadmap for potential molecular interactions. Molecular docking simulations revealed that the complex exhibits high binding affinities toward MGLL (-8.3 kcal/mol) and COX-2 (PDB: 5IKQ) (-9.5 kcal/mol), forming stable interaction networks through conventional hydrogen bonds and pi-cationic contacts. These findings, corroborated by SwissTargetPrediction and pharmacophore mapping, suggest that the copper(II) complex is a rational candidate for further investigation in metabolic regulation and anti-inflammatory therapeutic strategies.

In this study, five homoconjugated NLOphore candidates decorated with indole donor groups were synthesized in 55-85% yields via click-type formal [2 + 2] cycloaddition reactions. The obtained compounds were subsequently transformed into spirocyclic push-pull-type chromophores through thermal rearrangements, affording the corresponding spiro products in 54-80% yields. During the formation of the spiro derivatives, the commonly reported low-yield issue associated with aniline-containing substrates in the literature was successfully overcome through the incorporation of indole donor groups, enabling the efficient formation of the target structures. All target compounds were investigated by UV/vis spectroscopy, thermogravimetric analysis (TGA), theoretical calculations, and custom-made Z-scan experiments. The homoconjugated structures exhibit intramolecular charge-transfer (ICT) absorption bands between 496 and 619 nm, whereas the spiro derivatives display lambda max values in the range of 464-471 nm. TGA analysis revealed that the rigid spiro framework contributes to enhanced thermal stability compared to the homoconjugated chromophores. The ICT characteristics of the target molecules were examined in detail through frontier molecular orbital depictions, electrostatic potential maps, and timedependent density functional theory (TD-DFT) calculations. In addition, the calculated first hyperpolarizability values indicate that all chromophores possess significant potential as nonlinear optical (NLO) materials. In this context, the NLO properties were experimentally investigated using a custom-designed Z-scan system. The homoconjugated chromophore series exhibited nonlinear refractive index values (n2) ranging from -4.20 x 10- 7 to -22.30 x 10- 7 cm2 W- 1. A similar, yet even more pronounced trend was observed in the spirocyclic chromophore series, with n2 values ranging from -2.91 x 10- 7 cm2 W-1 to -46.21 x 10- 7 cm2 W-1. Overall, the theoretical and experimental results show good agreement, supporting the potential of these chromophores as promising NLOphore candidates.

When benzaldehyde, acetophenone, and thiourea are condensed in the presence of HCl, a compound, which is 4,5,8a-triphenylhexahydropyrimido[4,5-d]pyridine-2,7(1H,3H)-dithione (THPD) is derived (Barbero et al., A Br & oslash;nsted acid catalysed enantioselective Biginelli reaction. Green Chem. 2017;19:1529-1535. doi:). The structure of the compound synthesized was confirmed by using the single crystal X-ray diffraction technique, which showed that the asymmetric unit consisted of two crystallographically independent molecules with the core being a fused hexahydropyrimido[4,5-d]pyrimidine. The hydrogen bonding and aromatic ring interactions to support crystal packing were investigated by Hirshfeld surface analysis. The electronic structure and charge-transfer properties of the title compound were investigated using density functional theory (DFT) calculations to complement the experimental crystal structure. The results of single-crystal X-ray and optimized geometrical parameters are satisfactory and support each other. The frontier molecular orbital analysis reveals a moderate HOMO-LUMO energy gap, indicating balanced charge-transfer capability and chemical stability. Natural bond orbital investigations and molecular electrostatic potential studies underline strong intramolecular N-S-C conjugation and donor-acceptor nature, which is consistent with the solid-state packing nature, as reported. Molecular docking studies against human DNA topoisomerase II alpha revealed moderate binding affinity and favorable interactions within the protein-DNA binding region.

The reaction of 2-aminopyridine with mercaptoacetic acid was carried out in a benzene solution at a molar ratio of the initial components of 1:1. The thiylated reaction of p-bromoacetophenone with mercaptoacetic acid was carried out in a benzene solution, with a molar ratio of the initial components of 1:4. As a result, new compounds were obtained: 2-aminopyridin-1-ium-2,2 '-disulfanediyldiacetate (ASA) and 1,1-bis-(carboxymethylthio)-1-p-bromophenylethane (BSA). The structure of the newly synthesized compounds was confirmed by using single crystal XRD technique. The structure of ASA is a salt in which there exist two cations and one dianion in the asymmetric unit. The cations and dianions are interlinked by N-H & sdot;& sdot;& sdot;O and C-H & sdot;& sdot;& sdot;O bonding and further stabilization of the crystal packing is due to weak pi & sdot;& sdot;& sdot;pi and C-O & sdot;& sdot;& sdot;pi interactions. In second compound BSA, molecules are interlinked in the form of dimers through O-H & sdot;& sdot;& sdot;O bonding to complete two R22(8) loops and consecutive dimers are connected by C-H & sdot;& sdot;& sdot;Br bonding. Hirshfeld surface analysis is carried out for the exploration of the molecular interactions in terms of interatomic contacts. The theoretical investigation of two related organic compounds, ASA and BSA, using density functional theory (DFT) and related computational tools to evaluate their structural, electronic, and intermolecular interaction properties. Optimized geometries, frontier molecular orbitals (HOMO-LUMO), electrostatic potential (ESP) maps, and dipole moments were obtained using the B3LYP/6-311+G(d,p) level of theory. The analysis of electron localization function (ELF), reduced density gradient (RDG), and topological parameters (via QTAIM) provided insights into electron density distribution, hydrogen bonding, and interaction strengths within the molecules. Hirshfeld surface analysis was performed using Crystal Explorer to explore intermolecular interactions and visualize contact contributions in the crystal state. The findings suggest that ASA, with its higher dipole moment, lower energy gap, and stronger electrophilic nature, exhibits superior potential as a corrosion inhibitor compared to BSA.

The rise of resistance to existing antimicrobial drugs has become a significant global health concern, underscoring the urgent need for new and effective antimicrobial agents. In this context, we prepared six copper(II) (Cu1-Cu6) and six zinc(II) (Zn1-Zn6) complexes bearing N2O2-thiosemicarbazones and confirmed their structures by spectral techniques, including X-ray diffraction analysis. The antimicrobial potential of the target compounds was initially tested against drug-sensitive and isoniazid-resistant Mycobacterium tuberculosis strains. Cu(II)-based complexes were identified as more effective antitubercular agents with negligible cytotoxicity compared to Zn(II)-including counterparts. Furthermore, Cu1-Cu6 and Zn1-Zn6 were tested for their antibacterial and antifungal properties. Although the compounds failed to inhibit the growth of bacterial and fungal strains at low concentrations, Zn1 and Zn2 were determined as effective blockers of the bacterial cell-to-cell communication system known as quorum sensing. Finally, molecular docking studies indicated that inhibiting the enoyl acyl carrier protein reductase (InhA) enzyme could be the mechanism behind the significant antitubercular activity of Cu2. Overall, our study shows that copper(II) and zinc(II) complexes of thiosemicarbazones are promising agents against bacterial infections due to their antitubercular and anti-quorum sensing activities.

To meet the challenge of developing efficient energy storage devices, metal organic frameworks (MOFs) with intrinsic properties have emerged as promising candidates. The conductivity and stability of the extended 1D π-d and π-π stacking in a 2D MOF can be further enhanced by fabricating its composite with conductive materials. Herein, a nitrogen-containing 2D Cu-PDA MOF was synthesized and mixed with conductive materials, such as reduced graphene oxide (rGO) and polyaniline (PANI), to enhance the electrical conductivity. After structural investigation, the electrochemical attributes of Cu-PDA and its composites (Cu-PDA@rGO and Cu-PDA@PANI) have been explored by utilizing different electroanalytical techniques like CV, GCD and EIS analyses. In a three-electrode assembly, Cu-PDA@rGO shows a specific capacity of 551.31 C g-1. Hence, for practical applications, a hybrid supercapacitor has been designed by fabricating Cu-PDA@rGO against activated carbon (AC), which reveals a specific capacity of 159.4 C g-1, a specific energy of 32.10 Wh kg-1 and a specific power of 180.17 W kg-1 while maintaining a coulombic efficiency of 99.4% even after 5000 GCD cycles. These excellent findings demonstrate that Cu-PDA@rGO is a potential candidate for future energy storage devices.

In this study, a novel boron-containing polyoxometalate (BPOM) coordination polymer, Na5[trea]3[BW12O40]& sdot; 3H2O (Compound 1; trea = triethylamine), with a molecular weight of 3329.57 g/mol, was synthesized and comprehensively characterized by elemental analysis, single-crystal X-ray diffraction, NMR and FT-IR spectroscopy. Antimicrobial assays demonstrated that Compound 1 exhibited MIC values ranging from 62.5-1000 mu g/mL (1.88x10-5-3.00x10-4 M) for Gram-positive strains and 3.9-62.5 mu g/mL (1.17x10-6-1.88x10-5 M) for Gram-negative strains. The strongest inhibition was observed against Arcobacter butzleri AB5 with a MIC of 3.9 mu g/mL (1.17x10-6 M) and MBC of 7.18 mu g/mL (2.15x10-6 M). For Staphylococcus aureus ATCC 29213, MIC and MBC were 62.5 mu g/mL (1.88x10-5 M) and 250 mu g/mL (7.51x10-5 M), respectively. For Listeria monocytogenes, MIC values were 250-1000 mu g/mL (7.51x10-5-3.00x10-4 M). Antibiofilm testing using a virulent Escherichia coli wild-type strain revealed a concentration-dependent inhibition, with 72% biofilm reduction at 1000 mu g/mL (3.00x10-4 M) and 60%, 56%, 48%, 37%, and 21% reduction at 500, 250, 125, 62.5 and 31.2 mu g/mL, respectively. Haemolysis assays showed 0% erythrocyte lysis up to 1000 mu g/mL, indicating non-toxic behavior toward red blood cells. DNA interaction experiments using pBR322 plasmid DNA demonstrated no conversion of supercoiled Form Ito nicked (Form II) or linear DNA (Form III) at 1000 mu g/mL (3.00x10-4 M) or 500 mu g/mL (1.50x10-4 M) after 4 h incubation at 37 degrees C, indicating absence of DNA cleavage activity. These data position boron-substituted polyoxometalates as promising antimicrobial and antibiofilm candidates with clearly defined quantitative performance parameters.

A new hybrid compound containing 1,2,4-triazole ring and thiophene-2-carboxamide moieties was synthesized and evaluated for biological activity. The structure of this compound was determined using single-crystal diffraction (XRD), IR, 13C and 1H -NMR spectral data. In the present study, in silico studies including DFT (Density Functional Theory) calculations, molecular docking studies and MD (Molecular Dynamics) simulations were also performed to investigate the synthesized compound computationally. In the computational part of the study, conformational analysis, geometry optimization, molecular electrostatic potential map calculation, 1H and 13C NMR spectral analyses were carried out. Molecular docking studies were carried out to investigate the interactions between the synthesized compound and some selected target biomolecules related to the microorganisms tested in the biological activity experiments. MD simulations were also carried out in the present study to investigate whether the ligand-receptor complexes obtained from molecular docking studies can form stable structures. Additionally, the in vitro antimicrobial activity of synthesised compounds was evaluated against various bacterial and fungal species using the microdilution method (MIC) The results revealed that the most potent compound, II, demonstrated superior antimicrobial activity against S. aureus, E. faecalis, and P. aeruginosa compared to the reference antibiotics Amoxicillin and Tetracycline. Therefore, this compound can be considered as bioactive agents for pharmacological and medical applications.

New thiosemicarbazone-based Ni(II) complexes, [Ni(L1-3)] (1-3), were synthesized, structurally characterized, and evaluated for their cytotoxic potential in a panel of human cervical (HeLa), lung (A549), breast (MDA-MB-231), and pancreatic (PANC-1) cancer cells, along with a non-cancerous human embryonic kidney (HEK-293) cell line. The complexes exhibited selective cytotoxic effects, with HeLa cells showing the highest sensitivity. Among them, complex 2 demonstrated the most pronounced antiproliferative activity and selectivity compared to complexes 1 and 3. Cellular studies in HeLa cells revealed increased oxidative stress markers, mitochondrial dysfunction, and apoptosis-related alterations accompanying the observed cytotoxicity. Chemical antioxidant assays indicated higher radical-scavenging activity for the free ligand, whereas complex 2 displayed the highest TEAC value among the metal complexes. To support the experimental findings, computational studies including quantum chemical calculations, molecular docking, molecular dynamics simulations, and MM/GBSA analyses were performed, revealing favourable electronic properties and stable interactions of the complexes with the PI3Kα/mTOR kinase. Overall, the combined experimental and computational results highlight complex 2 as a promising Ni(II)-thiosemicarbazone scaffold with selective cytotoxic activity associated with altered oxidative stress parameters.

5,6-Dichloro-1H-benzimidazol-2-yl-(4'/5'/6'-substituted)-phenols (HL1-HL20) and MCl2 complexes (M: Co, Ni, Cu, Zn, Pd) of HL1 were synthesized and characterized by various physicochemical and spectroscopic methods such as elemental analysis, thermogravimetric analysis, FTIR, NMR and fluorescence spectroscopy. The structures of the complexes were also confirmed by performing molar conductivity and magnetic moment measurements. HL1 acted as a bidentate, monobasic chelating ligand with NO donor sites in all the complexes. It was found that all complexes have non-electrolytic properties and the M:L ratios are 1:1 in the Zn(II) complex and 1:2 in the other complexes. Crystal structure of HL18 was also investigated. The presence of both intra-and inter-molecular hydrogen bonding was observed in both molecules. According to the fluorescence spectral data, the substituents at the 4-position made the fluorescence emission shifted to the lower wavelengths (redshift) compared to HL1, while the substituents at the 3-and 5-positions caused a blue shift effect. The Zn(II) complex showed a greater redshift effect compared to the other complexes. In addition, antimicrobial activity of the compounds was evaluated against six bacteria and three fungi. It was observed that HL1 and its mono substituted derivatives (HL1-HL11) show selective activity especially against Gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis. Zn(II) complex showed relatively higher activity against Gram-positive bacteria differently from the other complexes.

This study provides insight into the donor characteristics of the indole framework and allows a comparison between its C-2 and C-3 positions. Ten electron-rich alkynes incorporating an indole core were synthesized via the Sonogashira cross-coupling reaction. Structural variations within these substrates led to two distinct reaction pathways for the formation of cyano-containing conjugated systems, yielding eight tricyanovinylation and two [2 + 2] cycloaddition-retroelectrocyclization (CA-RE) products. The tricyanovinylation products formed with tetracyanoethylene (TCNE) were obtained in 40-82% yields, whereas the chromophores produced through the [2 + 2] CA-RE pathway arising from alkyne activation were isolated in 30-63% yields. They display pronounced intramolecular charge transfer (ICT), with λmax values ranging from 494 to 504 nm for the tricyanovinylation products, while the two [2 + 2] CA-RE chromophores absorb at 471 and 495 nm. The observed ICT bands are supported by UV/vis studies by positive solvatochromism and protonation experiments. To clarify the relationship between NLO response and ICT properties, the dipole moment, band gap, electronegativity, average global hardness-softness, average polarizability, and first hyperpolarizability parameters were evaluated using computational methods. In addition to theoretical DFT calculations, the EFISHG technique was employed to investigate the NLO properties. The experimental μβ values of the selected molecules range from 150 to 560 × 10-48 esu.

ABSTRACT Theophylline, a naturally occurring xanthine derivative with well‐established pharmaceutical applications, has recently emerged as an attractive scaffold in coordination chemistry and catalysis because of its unique heterocyclic structure and donor properties. In this study, two novel N(7)‐substituted theophylline derivatives, namely 1,3‐dimethyl‐7‐((2,3,5,6‐tetramethyl)benzyl)‐3,7‐dihydro‐1 H ‐purine‐2,6‐dione and 1,3‐dimethyl‐7‐((2,3,4,5,6‐pentamethyl)benzyl)‐3,7‐dihydro‐1 H ‐purine‐2,6‐dione, were synthesized and comprehensively characterized by spectroscopic methods, single‐crystal x‐ray diffraction analysis, and density functional theory (DFT) calculations. Structural and theoretical investigations were carried out to evaluate their electronic features, coordination behavior, and potential interaction sites. For the first time, these theophylline‐based heterocyclic compounds were employed as ligand‐like components in in situ generated palladium catalytic systems for C─H bond activation reactions. The catalytic results demonstrated that the N(7)‐substituted theophylline framework effectively stabilizes palladium intermediates and promotes selective C─H functionalization under mild reaction conditions. DFT studies further revealed that the nitrogen donor centers of the theophylline scaffold play an important role in tuning the electronic properties and reactivity of the palladium species. In addition, frontier molecular orbital analyses, including HOMO–LUMO energy levels and orbital localizations, provided insight into the possible coordination and interaction regions of the molecules. These findings establish N(7)‐substituted theophylline derivatives as a new class of ligand‐like scaffolds for Pd‐catalyzed C─H activation.

In this work, 4-aminoantipyridine based Schiff base ligands and their novel palladium complexes were prepared and characterized by FT-IR spectroscopy, UV-Vis spectroscopy, elemental analysis, NMR and HRMS techniques. The spectroscopic and analytical data have revealed that the ligand: Pd(II) ratio is 1:1 for all complexes. The molar conductivity of complexes indicates that they are non-electrolytes. Besides this, X-ray crystallography has been employed to characterize the solid structures of ligand 6. The antibacterial activities of ligands and complexes against gram positive and gram negative bacteria. The best results were obtained for 7 in gram positive bacteria and 9 in gram negative bacteria. In the cytotoxicity study, all of the compounds exhibited cytotoxic effects on the cancerous OUMS cells, with ligand 4 showing the lowest IC50 value. About the antioxidant properties, when tested against ascorbic acid, a standard reference, complex 8 at 1450 µM showed significantly higher antioxidant activity. Overall, the synthesized 4-aminoantipyridine-based Schiff base palladium complexes exhibit promising antioxidant activities and cytotoxic effects. Further research is needed to elucidate their mechanism of action and evaluate their in vivo efficacy and safety profiles. The synthesized compounds were optimized using the DFT method, and HOMO–LUMO and MEP analyses were performed. Their interactions with VEGFR2 and TIE-2 proteins were investigated through molecular docking, and compounds 4 and 9 stood out with strong binding energies and experimental cytotoxicity.

In this study, three novel palladium(II) complexes based on S-methylthiosemicarbazone ligands derived from 1,3-butanedione and 2,4-pentanedione-functionalized with methyl (CH3), trifluoromethyl (CF3), and thiophene groups-were synthesized and structurally characterized by spectroscopic methods and single-crystal X-ray diffraction. To evaluate their potential as VEGFR-2 inhibitors, a comprehensive computational investigation was performed. Molecular docking and molecular dynamics (MD) simulations were employed to assess the binding affinities and dynamic stability of the co-ligand (colig) and three complexes (comp1, comp2, and comp3) with the VEGFR-2 receptor (PDB ID: 3CJG). Binding analyses consistently identified colig as the most potent binder, exhibiting the most favorable binding free energy (triangle G(bind) of -106.282 kJ/mol). MD simulations revealed two distinct stability profiles: colig and comp1 formed highly stable and rigid complexes, confirmed by low RMSD and RMSF values. In contrast, comp2 and comp3 were found to be significantly more flexible. Per-residue energy decomposition revealed that this stability is achieved through two different mechanisms: superior van der Waals interactions for colig, and a powerful electrostatic anchor with ASP1044 for comp1. Additionally, MTT assays on HUVEC cells revealed low cytotoxicity (IC50 > 50 mu M) for all synthesized complexes. Considering its high dynamic stability, unique electrostatic binding mechanism, and favorable safety profile, comp1 emerges as the most promising synthesized candidate for further development. These combined findings provide valuable insights for designing next-generation palladium(II)-based VEGFR-2 inhibitors.

In this study, compound 2, a novel Schiff base ligand containing an aminothiophene group, was synthesized and thoroughly characterized. The amine precursor (1) was condensed with 5-chloro-2-hydroxybenzaldehyde to yield the target ligand in high yield (90%). The ligand's structure was confirmed using FT-IR, 1H NMR, 13C-APT NMR, LC-MS (-ESI), and elemental analysis. The crystallographic study revealed that the ligand is arranged in the triclinic P & imath; space group, with two molecules present in each unit cell. The measured C7-N1 and C10-O2 bond lengths exhibit double-bond character, and the phenyl-thiophene dihedral angle of 6.02 degrees points to an almost planar structure. A hydrogen bond formed within the molecule between the phenolic-OH and imine nitrogen, and pi & sdot;& sdot;& sdot;pi interactions between adjacent molecules enhanced crystal stability. The ligand reacted with Co2+ and Ni2+ salts under reflux conditions to afford the corresponding metal complexes (3 and 4). Analysis by FT-IR revealed that the phenolic-OH band vanished, while the C = O and imine (C = N) groups participated in coordination. The imine stretching shift indicated nitrogen coordination, and the additional bands in the 655-531 cm-1 region verified metal-oxygen interactions. Elemental analyses matched the proposed molecular formulas, and magnetic susceptibility measurements indicated octahedral Co2+ and Ni2+ centres with paramagnetic properties. Thermal analyses revealed a multi-step decomposition process, ultimately yielding metal oxides (CoO, NiO) as the final residues. This study demonstrates that the Schiff base ligand acts as a bidentate (O, N) chelating agent, forming stable metal complexes. The ligand and its complexes, due to the imine group, thiophene ring, and heterocyclic structure, offer potential antimicrobial, anticancer, antioxidant, and sensor applications. These results underscore the role of Schiff bases and transition metal complexes in catalysis, materials science, and bioinorganic applications.

Two new quinoline-containing compounds namely, 3-(5-chloro-2-methoxyphenyl)quinoline (CMPQ) and 5-(quinolin-3-yl)thiophene-2-carbaldehyde (QYTC) have been synthesized by Suzuki-Miyaura Cross Coupling reaction. The synthesized compounds have been characterized by various spectroscopic techniques namely FTIR, UV-visible, 1H-NMR and 13C-NMR. Moreover, crystal structure of compounds has been determined by single-crystal X-ray diffraction (SC-XRD). The crystallographic study shows that in CMPQ, the quinoline-phenyl dihedral angle is 50.97° with a distinctly twisted conformation, while the two independent QYTC molecules are nearly planar with quinoline- thiophene angles of 6.36 and 1.91°. This conformational difference results from ortho-methoxy steric hindrance in CMPQ and stronger π-conjugation in QYTC. Hirshfeld surface analysis is done to order to explore the crystal packing of CMPQ and QYTC. Hirshfeld surface analysis showed that the top three contributors in stability of the crystal packing of CMPQ are H⋯H, H⋯C and H⋯N contacts while the packing of QYTC is mainly stabilized by H⋯H, H⋯O and H⋯C contacts. DFT calculations at the B3LYP/def2-SVP level reproduced the main conformational features. The HOMO–LUMO gaps of CMPQ and QYTC were 4.38 and 3.69 eV, respectively, which suggested that QYTC was more electronic soft with better charge-transfer ability. The results demonstrate the significant influence of the substituent-controlled conformation on the crystal packing and electronic properties of quinoline-containing compounds.