Dimethylselenide (Me2Se), a simple and small organochalcogen, has been used as a ligand to synthesize complexes [PdII(Me2Se)2Cl2] (1) and [RuII(p-cymene)(Me2Se)2Cl](PF6) (2). Complexes 1 and 2 have been characterized by multi-nuclear...

Herein, we present a square planar Ni(II) cooperative catalyst affixed with azo- and amido-based ligands that has been effectively employed for accessing highly substituted quinolines utilizing 2-aminoaryl alcohols with 2°-alcohols. Additionally, we report the synthesis of 1,2,3,4-tetrahydroquinolines (1,2,3,4-THQs) by transfer hydrogenation of quinolines with borazane (H3N·BH3).

Ruthenium(II)-polypyridyl metalloreceptor Ru-Q1, featuring integrated anion-binding functionalities, has been systematically evaluated for its anion sensing ability. Among various analytes, Ru-Q1 exhibited high selectivity and sensitivity towards biogenic phosphate ions (H2PO4- and HP2O73- ), showing pronounced luminescence quenching and bathochromic shifts. Photoluminescence titrations revealed low detection limits of 0.813 mu M for H2PO4- and 0.6 mu M for HP2O73- , respectively, with binding constants of 8.5 x 104 M- 1 and 4.5 x 105 M- 1. Competitive ion studies confirmed the excellent selectivity of Ru-Q1, even in the presence of potentially interfering metal ions. Mechanistic insights were gained through Job's plot analysis, 1H NMR titration, FE-SEM, emission lifetime studies, and DFT calculations. The probe's applicability in biological contexts was demonstrated via luminescence imaging in HepG2 cells. Preliminary data also indicate potential antimicrobial activity, highlighting the need for in-depth investigation.

Catechol-derived Schiff bases serve as versatile platforms for anion sensing, where intramolecular hydrogen bonding governs recognition and photophysical behavior. We report a catechol-based probe, PyCt, capable of discriminating cyanide (CN-) and fluoride (F-) via distinct hydrogen-bonding modes. Spectroscopic analyses reveal that CN- forms hydrogen bonds with the phenolic -OH without full deprotonation, while F- induces complete deprotonation, disrupting the hydrogen-bonding network. These interactions yield pronounced fluorescence enhancements at 535 nm (CN-) and 544 nm (F-), attributed to enhanced intramolecular charge transfer (ICT) that stabilizes the excited state and promotes radiative decay. Job's plot, 1H NMR and DFT studies confirm a 1:1 binding stoichiometry, with detection limits of 0.42 μM (CN-) and 1.20 μM (F-). PyCt demonstrates reversible recognition, high selectivity, and reliable sensing in real food samples. Furthermore, smartphone-assisted RGB analysis enables facile F- quantification, underscoring the probe's practical applicability.

Developing efficient and selective chemosensors for metal ion detection is essential for environmental monitoring, biological applications, and industrial processes. Herein, we report the synthesis of a novel colorimetric chemosensor, PCNTH2, derived from pyridine-2,6-dicarboxylic acid and 5-nitrothiazol-2-amine, capable of selectively detecting Cu2+ ions with high sensitivity. The chemosensor exhibits a distinct colour change upon binding with the target ions, enabling naked-eye detection without sophisticated instrumentation. UV-Vis spectroscopic studies reveal strong and specific interactions between the chemosensor and Cu2+ ions, with detection limits in the micromolar range. Job's plot analyses indicate a 1:1 stoichiometric complexation, supported by density functional theory (DFT) calculations and spectral data. This work underscores the potential of PCNTH2 as a versatile platform for ion detection in diverse applications.

KRS-1, a biocompatible nickel(II) complex, is introduced as a potent fluorescent probe for PrP106-126 fibrillar aggregates. KRS-1 shows a 15-fold enhancement in PL intensity and detects all stages of PrP106-126 aggregation. Fluorescence microscopy confirms its efficacy in identifying PrP106-126 fibrillar aggregates in HT-22 cells.

A new naphthalene-derived Schiff base probe, 1-((2-(diphenylphosphino)ethylimino)methyl)naphthalen-2-ol (HL), has been demonstrated for fluorometric detection of Al3+ and Zn2+ ions. HL was characterized by elemental analysis, FT-IR, NMR, UV-Vis, fluorescence, and ESI-MS analyses. It exhibited high sensitivity and selectivity toward Al3+ and Zn2+ ions in a semi-aqueous medium (CH3CN-H2O; 4 : 1, v/v), remaining unaffected by other competing metal ions. As a 'turn-on' fluorogenic probe, HL displayed strong emission enhancements at 430 nm and 450 nm (λex 300 nm) upon the addition of Al3+ and Zn2+ ions, respectively, with detection limits of 0.62 μM for Al3+ and 0.54 μM for Zn2+. The addition of Al3+ caused ca. 20 nm blue-shift in emission and absorption maxima of HL due to strong complex formation. The calculated binding constant values were found to be 1.39 × 103 M-1 and 4.78 × 103 M-1, respectively, for Al3+ and Zn2+ ions. Job's plot, NMR, ESI-MS, and density functional theory (DFT) studies supported the metal ion binding mechanism with 1 : 1 stoichiometry. Fluorescence imaging experiments further revealed HL's ability to detect intracellular Al3+ in live cells with very low cytotoxicity, highlighting its potential as a selective chemosensory probe.

A 2-(methylthio)aniline based palladacycle [PdII(L)Cl] (1) {where HL = 2-(methylthio)-N-(naphthalen-1-ylmethylene)benzenamine} has been synthesized and characterized by 1H, 13C{1H} NMR, UV-Vis, FT-IR and ESI-MS techniques. The coordination mode of HL in 1 was determined using single-crystal X-ray crystallography. The molecular structural elucidation revealed the orthometallation of Pd(II) with naphthalene moiety in 1. Ligand HL coordinated to Pd(II) via thioaniline-S and imine-N atoms, leading to a distorted square planar geometry around the Pd metal centre. The Pd-N and Pd-S bond distances were depicted as 2.001(8) & Aring; and 2.374(3) & Aring;, respectively. Complex 1 was found to be a highly efficient catalyst for Sonogashira (copper and amine free) and Suzuki-Miyaura cross coupling reactions of various aryl halides under aerobic conditions. The required amount of catalyst to achieve a good to excellent catalytic conversion was 0.01-0.05 mol%. During the course of coupling using 1 as catalyst, unexpected formation of Pd(0) nanoparticles PdNPs1 has been observed. These in-situ generated NPs have been characterized using transmission electron microscopy (TEM), EDAX, EDS mapping, UV-Vis, FT-IR and powder X-ray diffraction (PXRD) studies.

In this article, a chloro-bridged dinuclear ruthenium complex Ru-(a) has been synthesized, which was employed for the synthesis of a photolabile NO liberating complex Ru-(b). A newly synthesized tridentate ligand 2-methyl-6-((2-phenyl-2-(pyridin-2-yl)hydrazineylidene)methyl)pyridine with three N-atoms as donating site was used to synthesize the complex Ru-(a). The molecular structure of Ru-(a) was investigated by single-crystal X-ray crystallography and, in solution was characterized by or ESI mass spectrometry. Several spectroscopic techniques were applied for the characterization of the ligand as well as complexes. To understand the electronic structure of Ru-(a), DFT, as well as TD-DFT computations were utilized. By the utilization of visible light, photo-liberation experiments were examined. The amount of NO released during the photodissociation experiment was measured using the Griess assay technique. The photodissociated NO was fruitfully transported to reduced myoglobin (Mb). The antibacterial activity against Escherichia coli was carried out with 31.2 μg/mL concentration of Ru-(b). In the final results, we detected considerable antibacterial activity against E. coli and showed >99 % inhibition of the bacterial cell after 120 minutes of the experiment on exposure to visible light. These investigations proposed that Ru-(b) could be employed to treat several topical deliveries of NO for treating various topical infections and bacterial infections.

This work describes a new well-defined, air-stable, phosphine free palladium(II) [Pd(L)Cl] (1) catalyst. This catalyst was utilized for N-alkylation of amines and indole synthesis where H2O was found to be the by-product. A broad range of aromatic amines were alkylated using this homogeneous catalyst with a catalyst loading of 0.1 mol%. Greener aromatic and aliphatic primary alcohols were utilized and a hydrogen auto-transfer strategy via a metal-ligand cooperative approach was investigated. The precursor of the antihistamine-containing drug molecule tripelennamine was synthesized on a gram scale for large-scale applicability of the current synthetic methodology. A number of control experiments were performed to investigate the possible reaction pathway and the outcomes of these experiments indicated the azo-chromophore as a hydrogen reservoir during the catalytic cycle.

In this report, we revealed a method for transfer hydrogenation of nitroarenes to the equivalent amines while using precisely formulated Co-based catalysts. To enable sustainable, environmentally friendly, and affordable production, ethanol is used as a solvent, and hydrazine hydrate is used as a source of hydrogenation. The mechanistic investigation demonstrated that Co(II) complexes were reduced to Co(0) nanoparticles under the reaction conditions. By utilizing XPS, SEM, TEM, AFM, and EDX investigation, Co(0) nanoparticles were identified. Catalyst recyclability and green solvents are essential aspects of the approach. Notably, the synthesis of a few clinically significant compounds, including benzocaine, butamben, dapsone, and paracetamol, showed the practical application of the present methodology.

Three novel cyclometalated ruthenium complexes ([Ru.L(9)] [Ru.L(10)] and [Ru.L(11)]) featuring azo functionalities were synthesized and characterized using a variety of spectroscopic techniques, namely FT-IR, electronic absorption spectroscopy, and ESI-MS. Representative solid-state structures of the acquired complexes were determined through X-ray crystallography. These complexes were evidenced to be efficient catalysts for the synthesis of various α-alkylated compounds utilizing simple acetophenone derivatives with easily affordable and economically viable alcohols, which were isolated and characterized via 1H and 13C NMR spectroscopy. The optimum reaction conditions were found by employing toluene as solvent and potassium tert-butoxide as a base at 115 °C temperature utilizing 0.8 mol % of catalyst [Ru.L(10)]. The yield of the desired compounds was found to be in the range of 83-97 %. Additionally, mass spectrometry provided insights into the in-situ generated ruthenium hydride and ruthenium alkoxy intermediates, shedding light on the catalytic mechanism.

In the last few decades, nitric oxide (NO) metal complexes and macromolecules have been extensively studied for their biological activities. The main interest is in designing of various molecules and strategies for on-demand delivery of NO to a specific biological target. Since NO is involved in different biological processes, such as vasodilation, apoptosis, neurotransmission, and antioxidant activities. NO-releasing molecules are widely tested for various clinical and therapeutic applications every year. This review has discussed the current research on various, organic, inorganic metal complexes and polymeric material-based NO-donors for biological applications and further discussed their future perspectives.

Zinc is one of the most vital components of the living system and is also involved in promoting various neurodegenerative diseases. Therefore, direct monitoring of Zn2+ in biological systems is essential for human well-being. In this work, a chemosensor probe (HL) based on pyridine was synthesised, characterised, and re-ported for its highly efficient recognition of the zinc ions. The chemosensing behaviour of HL was determined by fluorescence spectroscopy. The probe was extremely sensitive for Zn2+, with an intensity enhancement of over 80-fold and a low detection limit (LOD) of 4 x 10-10 M (0.4 nM), which is remarkably low. In the presence of Co2+, Cr3+, and Cu2+ metal ions, HL shows fluorescence quenching, probably due to their paramagnetic nature. This chemosensor probe was used for applications in cell imaging and sensing of the Zn2+-induced prion (PrP106-126) peptide aggregation.

Ligands derived from 2-(1-phenylhydrazinyl)pyridine and salicylaldehyde (HL1), 3-methoxysalicylaldehyde (HL2), 5-bromosalicylaldehyde (HL3), and 3,5-di-tert-butylsalicylaldehyde (HL4) react with [(VO)-O-IV(acac)(2)] in MeOH followed by aerial oxidation to give [(VO2)-O-V(L-1)] (1), [(VO2)-O-V(L-2)] (2), [(VO2)-O-V(L-3)] (3), and [(VO2)-O-V(L-4)] (4). Complex [(VO)-O-IV(acac)(L-1)] (5) is also isolable from [(VO)-O-IV(acac)(2)] and HL1 in dry MeOH. Structures of all complexes were confirmed by single-crystal X-ray and spectroscopic studies. They efficiently catalyze benzyl alcohol and its derivatives' oxidation in the presence of H2O2 to their corresponding aldehydes. Under optimized reaction conditions using 1 as a catalyst precursor, conversion of benzyl alcohol follows the order: 4 (93%) > 2 (90%) > 1 (86%) > 3 (84%) approximate to 5 (84%). These complexes were also evaluated for antifungal and antiproliferative activities. Complex 3 with MIC50 = 16 mu g/mL, 4 with MIC50 = 12 mu g/mL, and 5 with MIC50 = 16 mu g/mL are efficient toward planktonic cells of Candida albicans and Candida tropicalis. On Michigan cancer foundation-7 (MCF-7) cells, they show comparable cytotoxic effects and exhibit IC50 in the 27.3-33.5 mu g/mL range, and among these, 4 exhibits the highest cytotoxicity. A similar study on human embryonic kidney cells (HEK293) confirms their less toxicity at lower concentrations (4 to 16 mu g/mL) compared to MCF-7.

Amines, N-heterocyclic compounds, and their derivatives are ubiquitous in all naturally occurring compounds, particularly alkaloids, and are widely used in pharmaceuticals, agrochemicals, lubricants, and surfactants. The design of pincer type ligands and corresponding metal complexes is a fundamental step with a unique reactivity. In this article, the NNN-pincer type of ruthenium complexes were synthesized and analyzed using a variety of spectroscopic techniques, including UV-Visible, infrared, and NMR. The molecular structures of the complexes were examined by X-ray crystallography. These complexes were also employed to activate carbon and nitrogen (C-N bond) bonds in C-N coupling processes. This paper describes the synthetic approach, product purification, and spectroscopic characterization, and nuclear magnetic resonance (NMR) spectroscopy was used to demon-strate the catalytically synthesized substrates. A total number of 16 quinolines and 22 N-alkylated substrates were synthesized and characterized by NMR spectroscopic technique.

Nitric oxide (NO) molecule participates in various biological events such as vasodilation, neurotransmission, antioxidant, and immune responses. In living organisms, it is generated as a side product by nitric oxide synthase (NOS) enzyme via conversion of L-arginine to L-citrulline. The physiological role of NO is concentration-dependent, which is crucially important to obtain the desired effects in biosystem. Coordination complexes of NO with transition metals, especially ruthenium (Ru), have gained increasing interest for the past few decades. So far, several ruthenium nitrosyl complexes have been developed as NO carriers, and their photochemical properties are well documented in the literature. Most of the ruthenium nitrosyl (Ru–NO) complexes are found photolabile in nature and release NO molecule in the presence of the light of suitable wavelength. The photoreleased NO can stimulate various biological targets in different in-vitro and in-vivo models. The main motif of this book chapter is to cover majority of the light sensitive Ru–NO complexes, and the photochemical properties of these complexes, quantification, delivery and application of NO molecule for various biological targets are discussed at a length.

Cobalt complexes (1 and 2) supported by strong π-acidic ligands were synthesized and characterized. These complexes were employed as catalysts for the oxidation of sp 3 C–H bonds. Mechanistic pathways are proposed on the basis of experimental evidence.