Complexes 2a Research Articles

Synthesis and conjugation properties of alkynyl functionalized salicylidene Ni(II) and Zn(II) phosphine complexes and their use as a precursor for preparation of NiO and ZnO nanoparticles

The complexes of type [Ni(L1/L2 )(PPh3)2/dppe]NO3 (1a-4a) and [Zn(L1/L2 )(PPh3)2/(dppe)]NO3 (1b-4b) [where L1 = 2-((E)-(4-(2-(trimethylsilyl)ethynyl)phenylimino)methyl)-4-(2-(4-bromophenyl)ethynyl) phenol; L2 = 2-((E)-(4-(2-(trimethylsilyl)ethynyl)phenylimino)methyl)-4-(2-(4-methoxyphenyl)ethynyl) phenol; PPh3 = triphenylphosphine; and dppe = 1, 2-bis(diphenylphosphino)ethane] have been synthesized and characterized by elemental analyses, IR, UV–Vis, 1H NMR, and 31P NMR spectral studies. The ancillary phosphine ligands significantly perturb the metal to ligand charge transfer (MLCT) state of Ni(II) and Zn(II) complexes and associated with their electron donating character. The room temperature luminescence is observed for all complexes which corresponds to π→π* ILCT transition with some MLCT character. The second harmonic generation (SHG) efficiency of the complexes was determined by Kurtz-powder technique indicating that all complexes displayed the SHG property. Metal oxide nanoparticles were obtained by calcinations of representative complexes 1a and 4b at 600 °C and are characterized by FTIR, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction techniques.

A binuclear aluminium complex as a single competent catalyst for efficient synthesis of urea, biuret, isourea, isothiourea, phosphorylguanidine, and quinazolinones.

The synthesis and characterisation of two mononuclear aluminium alkyl complexes with the general composition [Al(Me)2{Ph2P(E)N(CH2)2N(CH2CH2)2O}] (E = Se (2a); S (2b)), and two binuclear aluminium complexes, [Al(Me)2{Ph2P-(E)N(CH2)2N(CH2CH2)2O}(AlMe3)] (E = Se (3a) and S (3b)), are described. The binuclear aluminium alkyl complex 3a proved to be a proficient catalyst for the addition of simple nucleophiles to heterocumulenes, leading to the synthesis of a variety of products such as urea, biuret, isourea, isothiourea, phosphorylguanidine, and quinazolinone derivatives, in contrast to its mononuclear analogues. Complex 3a is the first example of a single competent catalyst, which is also low-cost and eco-friendly and derived from a main-group metal, under solvent-free conditions either at room temperature or mild temperatures. Complex 3a possessed a wide functional group tolerance including heteroatoms, yielding the corresponding insertion products in good quantities and with high selectivity.

Synthesis of a diruthenium μ-η4-α-diimine complex via dehydrogenative coupling of cyclic amines and its role in dehydrogenative oxidation of pyrrolidine.

The reaction of [Cp‡Ru(μ-H)4RuCp‡] (1: Cp‡ = 1,2,4-tri-tert-butylcyclopentadienyl) with cyclic amines at 180 °C afforded a μ-η4-α-diimine complex, [(Cp‡Ru)2(μ-η4-C2nH4n-4N2)] (5a-c: n = 4, 5, 6), via dehydrogenative coupling of two cyclic amine molecules. An intermediate μ-η2-1-pyrroline complex, [{Cp‡Ru(μ-H)}2(μ-η2-C4H7N)] (2a), was synthesized by the photoreaction of 1 with pyrrolidine and 5a was shown to be formed via the disproportionation of 2a upon thermolysis yielding 1 and a μ-imidoyl complex, [(Cp‡Ru)2(μ-η2:η2-C4H6N)(μ-H)] (3a). Complex 3a was transformed into 5avia the incorporation of 1-pyrroline, which was formed by the reaction of 2a with H2. DFT calculations on the model complexes supported by C5H5 groups at the B3LYP level suggested that the μ-η4-α-diimine ligand is formed via the insertion of a terminal cyclic aminocarbene ligand into the Ru-C bond of the μ-imidoyl group followed by the elimination of hydrogen. Although 5a was inert under an Ar atmosphere, it catalyzed the dehydrogenative oxidation of pyrrolidine under an atmosphere of hydrogen to yield γ-butyrolactam. An active species possessing a terminal cyclic aminocarbene ligand was generated via the heterolytic activation of hydrogen at the Ru-N bond followed by C-C bond cleavage.

Dicationic copper(I) complexes bearing ENE (E = S, Se) pincer ligands; catalytic applications in regioselective cyclization of 1,6-diynes.

Two novel dicationic binuclear Cu(I) complexes of the type [{(BPPP)E2}Cu]2[BF4]2 (E = S (3a); Se (3b)) bearing (BPPP)E2 (BPPP = bis(diphenylphosphino)pyridine) pincer systems were isolated, and structurally characterized. The solid-state structures of 3a/3b display the presence of intermolecular cuprophilic (Cu⋯Cu) interactions between the two monocationic species, and consist of weak Cu⋯S bonding between the two cations. Besides, complex 3a was introduced as a molecular copper(I) catalyst in cyclization reactions, and new protocols were developed for the synthesis of a series of new oxazole and triazole derivatives bearing alkyne-phenyl propargylic ether substituents. 3a was also found to be active in achieving these two classes of heterocyclic compounds by the mechanical grinding method. One of the key intermediate copper-azide species was detected by the high-resolution mass spectrometry technique, which supports the proposed catalytic pathway. All the reported transformations were accomplished sustainably by employing a well-defined, earth-abundant, and cheap copper(I) catalytic system.

C-N linked donor type porphyrin derivatives: unrevealed hole-transporting materials for efficient hybrid perovskite solar cells.

A new series of Zn(II) and Cu(II)-based porphyrin complexes 5a and 5b doubly functionalised with carbazole units were developed to be used as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). These complexes were obtained via a nucleophilic substitution reaction mediated by PhI(OAc)2/NaAuCl4·2H2O, or using C-N transition metal-assisted coupling. The hole extraction capability of 5a and 5b was assessed using cyclic voltammetry; this study confirmed the better alignment of the Zn(II) complex 5a with the perovskite valence band level, compared to the Cu(II) complex 5b. The optimised geometry and molecular orbitals of both complexes also corroborate the higher potential of 5a as a HTM. Photoluminescence characterisation showed that the presence of 5a and 5b as HTMs on the perovskite surface resulted in the quenching of the emission, matching the hole transfer phenomenon. The photovoltaic performance was evaluated and compared with those of reference cells made with the standard HTM spiro-OMeTAD. The optimised 5-based devices showed improvements in all photovoltaic characteristics; their open circuit voltage (Voc) reached close to 1 V and short-circuit current density (Jsc) values were 13.79 and 9.14 mA cm-2 for 5a and 5b, respectively, disclosing the effect of the metallic centre. A maximum power conversion efficiency (PCE) of 10.01% was attained for 5a, which is 65% of the PCE generated by using the spiro-OMeTAD reference. This study demonstrates that C-N linked donor-type porphyrin derivatives are promising novel HTMs for developing efficient and reproducible PSCs.

New copper(I) complexes of bulky 5-substituted-2-iminopyrrolyl ligands as catalysts for azide-alkyne cycloaddition.

Five dinuclear copper(I) complexes of the type [Cu{κN,κN'-5-R-NC4H2-2-C(H)N(2,6-iPr2C6H3)}]2 (1a-e; R = 2,4,6-iPr3C6H2 (a), R = 2,6-Me2C6H3 (b), R = 3,5-(CF3)2C6H3 (c), R = 2,6-(OMe)2C6H2 (d), R = CPh3 (e)) were prepared by the reaction of the respective 5-R-2-iminopyrrolyl potassium salts KLa-e and [Cu(NCMe)4]BF4 in moderate yields. These new copper(I) complexes were characterized by NMR spectroscopy, elemental analysis and, in selected cases, by single crystal X-ray diffraction and their structural and electronic features further analyzed by DFT calculations and cyclic voltammetry, respectively. X-ray diffraction studies reveal dimeric Cu structures assembled by 2-iminopyrrolyl bridging ligands adopting a transoid conformation (complexes 1a and 1d), while complexes 1c and 1e displayed a cisoid conformation of those moieties, with respect to the Cu(I) centers. Additionally, VT-1H NMR and 1H-1H NOESY NMR experiments on complexes 1a-e exhibited complex fluxional processes in solution, assigned to a conformational inversion of the respective Cu2N4C4 metallacycles in all complexes but 1c, accompanied by a cisoid-transoid isomerization in the cases of complexes 1d,e. The Cu(I) complexes were also analyzed by cyclic voltammetry, where all complexes exhibit two oxidation processes, where the first oxidation is reversible, with the exception of 1b and 1c, which also show the highest oxidation potentials. The oxidation potentials follow clear trends related to the structural parameters of the complexes, in particular the Cu⋯Cu distance and the Cu2N4C4 macrocycles torsion angles. All new 5-substituted-2-iminopyrrolyl Cu(I) complexes 1a-e served as catalysts for azide-alkyne cycloaddition (CuAAC) reactions, being able to generate the respective 1,2,3-triazole products in yields as high as 82% and turnover frequencies (TOFs) as high as 859 h-1, after optimizing the conditions. The activity, as measured by the TOF, is in accordance with the oxidation potential of the corresponding complexes, the easier the oxidation, the higher the TOF value. Complex 1-H, where R = H, proved to be a poor catalyst for the same reactions, indicating that the 5-substitution in the ligand framework is crucial in stabilizing any potential catalytic species.

A series of boron difluoride complexes of azinylcarbazoles: synthesis and structure-property relationships.

A series of boron difluoride (BF2) complexes of azinylcarbazoles 1b-1h were synthesized, and the effects of the structure of azine moieties on the photophysical and electrochemical properties of the BF2 complexes were clarified. UV-vis analysis of 1b with quinoline, 1c with isoquinoline, and fully fused 1d revealed that fusion with a benzene ring to a pyridylcarbazole BF2 complex (1a) resulted in red shifts of longest-maximum absorption wavelengths (λmax). UV-vis analysis of 1e and 1f with pyrimidine, 1g with pyridazine, and 1h with pyrazine revealed that substitution of a carbon atom to a nitrogen atom in 1a also resulted in red shifts of λmax. The fluorescence quantum yields (Φf) decreased from 1a to 1b-1h, and especially, the fluorescence of 1e, 1g, and 1h was quenched in solution. At 77 K, the emission intensities of 1b-1h were significantly increased compared with those at ambient temperature, and they also exhibited phosphorescence with relatively narrow energy gaps between the singlet and triplet excited states. These results on the emission at 77 K indicate that the quench of fluorescence from 1e, 1g, and 1h at ambient temperature originates from both internal conversions and intersystem crossing. In the solid state, all of the complexes including 1e, 1g, and 1h exhibited emission. Distinctive aggregation-induced emission properties were observed for 1e-1h. Electrochemical measurements revealed that the replacement of the pyridine moiety in 1a with azine moieties reduced electrochemical gaps mainly due to a decrease in the LUMO levels. The effects of azine moieties on electronic structures were also discussed based on theoretical calculations.

Mononuclear discrete Ag(I) complexes of aryl substituted (E)-N-phenyl-1-(pyridin-3-yl)methanimine: In vitro biological activities and interactions with biomolecules

The synthesis of three pyridinyl imines (L1-L3) with electron-donating and electron-withdrawing functional groups, as well as their silver(I) complexes (1a-3a, 1b-3b and 1c-3c), resulted from our ongoing search for novel metallodrugs with potential pharmacological activity. Various analytical and spectroscopic analyses were used to characterize the Ag(I) complexes. The single crystal X-ray diffraction analysis of complexes 3a and 3b in the solid state confirmed their linear geometry around the Ag(I) center. In vitro antibacterial properties of the complexes evaluated using the minimum inhibitory concentration (MIC) method revealed that complexes containing either a Me- or an F-substituent exhibited greater activity. The ferric-reducing antioxidant power (FRAP) experiment revealed that complexes with hydroxyl substituents have high antioxidant potential. These complexes with IC50 values ranging from 0.86 to 2.47 mg mL-1 outperformed ascorbic acid, with an IC50 of 2.68 mg mL-1. The reported complexes bound to CT-DNA via intercalation mode with significant binding constants for complexes whose ligands bore the OH- substituent. Bovine serum albumin (BSA) binding affinity to the complexes ranges from moderate to high. The studied complexes with methyl substituents are promising anti-cervical cancer candidates.

Luminescent Pt(II) Complexes Containing (1-Aza-15-crown-5)dithiocarbamate and (1-Aza-18-crown-6)dithiocarbamate: Mechanochromic and Solvent-Induced Luminescence.

The strong tendency to stack in the solid state and rich luminescence for the Pt(II) complexes makes them potential candidates as new mechanochromic materials and sensing applications. Six mononuclear complexes [Pt(ppy)(O4NCS2)] (1), [Pt(bpy)(O4NCS2)]ClO4 (2), [Pt(ppy)(O5NCS2)] (3), [Pt(phen)(O4NCS2)]ClO4·CH3OH (5a), [Pt(phen)(O4NCS2)]ClO4 (5b), and [Pt(phen)(O5NCS2)]ClO4 (6a), one dinuclear complex [Pt2(phen)2(NaO5NCS2)2(ClO4)3]ClO4 (6b), and one one-dimensional (1-D) coordination polymer {[Pt2(bpy)2(NaO5NCS2)2(ClO4)2](ClO4)2}n (4) were synthesized by reacting [Pt(ppy)Cl]2, Pt(bpy)Cl2, and Pt(phen)Cl2 (ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine, and phen = 1,10-phenanthroline) with (1-aza-15-crown-5)dithiocarbamate (O4NCS2) or (1-aza-18-crown-6)dithiocarbamate (O5NCS2), respectively, which have been isolated and structurally characterized by X-ray diffraction. Neutral complexes 1 and 3 contain no intermolecular Pt(II)···Pt(II) contact, whereas cationic complexes 2, 5a, 5b, and 6a with ClO4- as counteranions show alternative intermolecular Pt(II)···Pt(II) contacts of 3.535/4.091, 3.480/5.001, 3.527/4.571, and 3.446/4.987 Å in the solid state, respectively. Interestingly, complex 4 forms a 1-D coordination polymer through coordination between the encapsulated Na+ ions inside the azacrown ether rings of O5NCS2 and ClO4- anions with respective intra- and intermolecular Pt(II)···Pt(II) contacts of 3.402 and 3.847 Å in crystal lattices, whereas a dinuclear complex 6b was surprisingly formed and also connected by the encapsulated Na+ ions and ClO4- anions with alternative intra- and intermolecular Pt(II)···Pt(II) contacts of 3.650 and 3.677/4.4.372 Å, respectively. Upon excitation, complexes 1 and 3 showed similar vibronic luminescence at 507, 534, and 502, 532 nm, respectively, and the other complexes 2 and 4-6 showed broad luminescence with maxima at 537-567 nm. The B3LYP/LanL2DZ calculation was carried out and used to clarify their excited-state properties. In addition, the powder samples for complexes 1-4 almost showed no energy shift for the luminescence and significantly those of complexes 5-6 exhibited the mechanochromic luminescence upon grinding. It is noted that complexes 5a and 6a only showed minor red shifts (i.e., from 544 to 556 nm for complex 5a and from 551 to 565 nm for complex 6a), whereas complex 6b exhibited a remarkable red shift from 558 to 603 nm upon grinding. Besides, their luminescence reversibility was also examined toward various solvents.

An Integrated Analysis of Mechanistic Insights into Biomolecular Interactions and Molecular Dynamics of Bio-Inspired Cu(II) and Zn(II) Complexes towards DNA/BSA/SARS-CoV-2 3CLpro by Molecular Docking-Based Virtual Screening and FRET Detection.

Novel constructed bioactive mixed-ligand complexes (1b) [CuII(L)2(phen)] and (2b) [ZnII(L)2(phen)] {where, L = 2-(4-morpholinobenzylideneamino)phenol), phen = 1,10-phenanthroline} have been structurally analysed by various analytical and spectroscopic techniques, including, magnetic moments, thermogravimetric analysis, and X-ray crystallography. Various analytical and spectral measurements assigned showed that all complexes appear to have an octahedral geometry. Agar gel electrophoresis's output demonstrated that the Cu(II) complex (1b) had efficient deoxyribonucleic cleavage and complex (2b) demonstrated the partial cleavage accomplished with an oxidation agent, which generates spreadable OH● through the Fenton type mechanism. The DNA binding constants observed from viscosity, UV-Vis spectral, fluorometric, and electrochemical titrations were in the following sequence: (1b) > (2b) > (HL), which suggests that the complexes (1b-2b) might intercalate DNA, a possibility that is supported by the biothermodynamic measurements. In addition, the observed binding constant results of BSA by electronic absorption and fluorometric titrations indicate that complex (1b) revealed the best binding efficacy as compared to complex (2b) and free ligand. Interestingly, all compounds are found to interact with BSA through a static approach, as further attested by FRET detection. The DFT and molecular docking calculations were also performed to realize the electronic structure, reactivity, and binding capability of all test samples with CT-DNA, BSA, and the SARS-CoV-2 3CLPro, which revealed the binding energies were in a range of -8.1 to -8.9, -7.5 to -10.5 and -6.7--8.8 kcal/mol, respectively. The higher reactivity of the complexes than the free ligand is supported by the FMO theory. Among all the observed data for antioxidant properties against DPPH᛫, ᛫OH, O2-• and NO᛫ free radicals, complex (1a) had the best biological efficacy. The antimicrobial and cytotoxic characteristics of all test compounds have been studied by screening against certain selected microorganisms as well as against A549, HepG2, MCF-7, and NHDF cell lines, respectively. The observed findings revealed that the activity enhances coordination as compared to free ligand via Overtone's and Tweedy's chelation mechanisms. This is especially encouraging given that in every case, the experimental findings and theoretical detections were in perfect accord.

Enriching Chemical Space of Bioactive Scaffolds by New Ring Systems: Benzazocines and Their Metal Complexes as Potential Anticancer Drugs.

The search for new scaffolds of medicinal significance combined with molecular shape enhances their innovative potential and continues to attract the attention of researchers. Herein, we report the synthesis, spectroscopic characterization (1H and 13C NMR, UV-vis, IR), ESI-mass spectrometry, and single-crystal X-ray diffraction analysis of a new ring system of medicinal significance, 5,6,7,9-tetrahydro-8H-indolo[3,2-e]benzazocin-8-one, and a series of derived potential ligands (HL1-HL5), as well as ruthenium(II), osmium(II), and copper(II) complexes (1a, 1b, and 2-5). The stability of compounds in 1% DMSO aqueous solutions has been confirmed by 1H NMR and UV-vis spectroscopy measurements. The antiproliferative activity of HL1-HL5 and 1a, 1b, and 2-5 was evaluated by in vitro cytotoxicity tests against four cancer cell lines (LS-174, HCT116, MDA-MB-361, and A549) and one non-cancer cell line (MRC-5). The lead compounds HL5 and its copper(II) complex 5 were 15× and 17×, respectively, more cytotoxic than cisplatin against human colon cancer cell line HCT116. Annexin V-FITC apoptosis assay showed dominant apoptosis inducing potential of both compounds after prolonged treatment (48 h) in HCT116 cells. HL5 and 5 were found to induce a concentration- and time-dependent arrest of cell cycle in colon cancer cell lines. Antiproliferative activity of 5 in 3D multicellular tumor spheroid model of cancer cells (HCT116, LS-174) superior to that of cisplatin was found. Moreover, HL5 and 5 showed notable inhibition potency against glycogen synthase kinases (GSK-3α and GSK-3β), tyrosine-protein kinase (Src), lymphocyte-specific protein-tyrosine kinase (Lck), and cyclin-dependent kinases (Cdk2 and Cdk5) (IC50 = 1.4-6.1 μM), suggesting their multitargeted mode of action as potential anticancer drugs.

Organotellurium(IV) complexes of N-methylisatin-o-aminothiophenol Schiff base: Preparation, characterization, DFT, molecular docking studies, antimicrobial and antioxidant activity

The reactions of organotellurium(IV) chlorides (RTeCl3 and R2TeCl2) with Schiff base(NMeIATP) derived by condensation of N-methylisatin with 2-aminothiophenol results in the formation of new organotellurium(IV) complexes (4a-4f) of type RTeCl2.NMeIATP and R2TeCl.NMeIATP (where R = 4-Methoxyaryl, 4-Hydroxyaryl and 3-Methy-4-hydroxyaryl; aryl = phenyl). These complexes were characterized by different experimental and spectroscopic techniques like elemental analyses, molar conductance, SEM analysis, FT-IR, DFT calculations, powder X-ray diffraction, mass spectrometry, 1H NMR, 13C NMR, UV–Vis and Thermogravimetric analysis. These spectroscopic studies revealed that ligand acted as monobasic tridentate ligand coordinated with tellurium metal through Carbonyl oxygen, azomethine nitrogen and sulphur atom from the 2-aminothiophenol ring. The molecular geometries of NMeIATP and its organotellurium(IV) complexes(4a-4f) were optimized and quantum mechanical parameters were calculated by using DFT/B3LYP basis sets in Guassian09 program. Based on the spectral results, suitable geometries of the complexes are purposed. Molecular docking studies were carried out to determine the binding energy between NMeIATP and complexes with receptor proteins: S. aureus (3ty7), B. subtilis (5h67) and E. coli (3t88). Antioxidant activity of NMeIATP and organotellurium(IV) complexes were evaluated by DPPH assay. The radical scavenging activity(IC50 value) of complex 4a (IC50 = 59.08 μg/ml) was found to be greater than other compounds. NMeIATP and organotellurium(IV) complexes were tested against different bacteria and fungi. MIC values show that complexes possess better antimicrobial activity than Schiff base (NMeIATP).

Well-Defined and Highly Effective Nickel Catalysts Coordinated on Tridentate SNO Schiff-Base Derivatives for Alternating Copolymerization of Epoxides and Anhydrides.

A series of Ni complexes supported by SNO Schiff-base derivatives were synthesized in this study. Complex synthesis and characterization data are reported herein. Treatment of the pro-ligands [L1-H = 2-(((2-(methylthio)ethyl)imino)methyl)phenol, L2-H = 2,4-di-tert-butyl-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L3-H = 2-(((2-(methylthio)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L4-H = 4-bromo-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L5-H = 4-chloro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded six-coordinate mono-Ni(II) complexes [L2nNi] (n = 1-5). Noteworthy, a heptanuclear nickel(II) octacarboxylate species complex 6 and dinuclear nickel complex 6a resulted from treatment of L6-H [4-fluoro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with different metal precursors [Ni(OAc)2·4H2O for 6; NiBr2 for 6a] giving a quantitative yield. The reaction of nickel acetate tetrahydrate and L7-H to L9-H [L7-H = 2-methoxy-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L8-H = 5-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L9-H = 4-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol] produced the four-coordinate complexes [L2nNi] (n = 7-9). The highest performing catalyst was complex 3, which was highly efficient for the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) in the presence of a cocatalyst (4-dimethylaminopyridine). In addition, the same copolymerization conditions produced narrowly dispersed polyesters, with high selectivity and polymerization control. In addition to PA-CHO copolymerization, efficient diglycolic anhydride-PA and PA-propene oxide copolymerization was achieved under the same conditions. These catalysts are straightforward to produce and extend the scope of potential substrates.

PNCNP Pincer Platinum Chloride Complex as a Catalyst for the Hydrosilylation of Unsaturated Carbon-Heteroatom Bonds

A PNCNP pincer-ligated platinum(II) chloride complex [2,6-(tBu2PNH)2C6H3]PtCl (1a) was synthesized and fully characterized. Complex 1a was applied to the catalytic hydrosilylation of unsaturated carbon-heteroatom bonds. For comparison, the corresponding hydride complex [2,6-(tBu2PNH)2C6H3]PtH (1b) and the related POCOP pincer chloride complex [2,6-(tBu2PO)2C6H3]PtCl (1c) were also used to catalyze the reactions. It was found that 1a is a good catalyst for the hydrosilylation of both C═O and C═N bonds. Wide ranges of aldimines, ketimines, aldehydes, and ketones were hydrosilylated, and the expected amine or alcohol products were obtained in good to excellent yields. The reactions also feature good functional group compatibility. Complex 1a represents the most effective transition metal catalyst for the hydrosilylation of the C═N bond and is among the best transition metal catalysts for the hydrosilylation of the C═O bond. The reactions are likely catalyzed by a cationic platinum(II) species generated from complex 1a during the reactions.

Metal complexes of ‘Heena’ (2-hydroxy-1,4-naphthoquinone): Synthesis, Characterization and anticancer activity

The Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of Henna; 2-hydroxy-1,4-naphthoquinone (Lw) are synthesized at 0 °C (Mn2+; 1, Co2+; 2, Ni2+; 3, Cu2+; 4 and Zn2+; 5), 26 °C (Mn2+; 1A, Co2+; 2A, Ni2+; 3A, Cu2+; 4A and Zn2+; 5A) and characterized. The compositions of all complexes are of the type [M(Lw)2(H2O)2]. The geometry of the complexes synthesized at 26 °C is trans, whereas cis for complex 4 at 0 °C. The pyridine adduct (4Apy) of copper complexes 4A and methanol (4MeOH) adduct of complex 4 is characterized by single crystal X-ray diffraction studies. The molecular interactions are revealed from the X-ray structures of 2A, 5A, 4Apy, and 4MeOH. Anticancer activity of all complexes was evaluated against two cancer cell lines, MCF-7 (breast cancer cell line) and A-549 (lung cancer cell line). The complexes synthesized at 0 °C show enhanced activity against the A549 cell line. Cell cycle analysis, effect on mitochondrial potential, estimation of Reactive Oxygen Species (ROS), effect on peripheral blood mononuclear cells (PBMCs), Tunnel assay, etc., experiments were performed on complex 1A.

Antiparasitic activities of bimetallic N‐heterocyclic carbene gold(I) complexes with ferrocene ligands: Relevance of chlorido and phosphino ligands

Gold(I) complexes carrying imidazole‐2‐ylidene ligands and ferrocene substituents were prepared. Their activities against protozoal Leishmania major and Toxoplasma gondii parasites were analyzed. Certain gold(I) complexes with chlorido and 1,1′‐bis(triphenylphosphino)ferrocene ligands revealed promising antiparasitic effects. The new chlorido complexes 5b and 5c showed high activities against T. gondii tachyzoites and L. major promastigotes while the new ferrocene‐bridged bis‐gold(I) complexes 8a and 8b were particularly active against L. major amastigotes and considerably selective as to toxicity results from Vero cells and macrophages.

A 2D Porous Zinc-Organic Framework Platform for Loading of 5-Fluorouracil

A hydrostable 2D Zn-based MOF, {[Zn(5-PIA)(imbm)]·2H2O}n (1) (5-H2PIA = 5-propoxy-isophthalic acid, imbm = 1,4-di(1H-imidazol-1-yl)benzene), was synthesized and structurally characterized. Complex 1 shows good water and thermal stability based on the TGA and PXRD analyses and displays a 2D framework with 1D channels of 4.8 × 13.8 and 10.0 × 8.3 Å2 along the a axis. The 5-fluorouracil (5-FU) payload in activated complex 1 (complex 1a) is 19.3 wt%, and the cumulative release value of 5-FU at 120 h was about 70.04% in PBS (pH 7.4) at 310 K. In vitro MTT assays did not reveal any cytotoxic effect of NIH-3T3 and HEK-293 cells when the concentration of 1 was below 500 μg/mL and 5 μg/mL, respectively. No morphological abnormalities were observed on zebrafish exposed to complex 1.

Synthesis, Structural Studies and Antimicrobial Evaluation of Nickel(II) Bis-Complex of Schiff Base of S-Benzyldithiocarbazate

A tridentate nitrogen-oxygen-sulfur (NOS) S-benzyl(2-oxoindolin-3-ylidene)dithiocarbazate, HSBISA (HL1) ligand was synthesized via a condensation reaction between S-benzylditihocarbazate (SBDTC) and isatin. The produced ligand was reacted with nickel(II) acetate salt in 1:2 (metal:ligand) ratio to yield a brown Ni(SBISA)2 complex (2) (SBISA = monoanionic form of HL1). Characterization of HL1 and its Ni(II) complex was performed via elemental analysis, FT-IR, ICP-AES, UV-Vis spectroscopy and mass spectrometry, along with molar conductivity and magnetic susceptibility measurement. Slow evaporation of 2 from DMSO at room temperature led to a structure crystallizing in the monoclinic P21/a space group with a = 18.6860(3), b = 11.3037(2), c = 19.8993(3), b = 112.1897(10), V = 3891.86(11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I). The nickel(II) metal center is ligated by doubly-deprotonated NOS monoanionic tridentate HL1 ligands forming a neural distorted octahedral Ni(SBISA)2×2DMSO (2a) complex. The antimicrobial assays of both compounds were performed on selected pathogenic bacteria and fungi strains. HIGHLIGHTS Octahedral Ni(II) complex was synthesized using acetate salt Compound was characterized via physico-chemical analyses Structural studies were resolved via single crystal X-ray diffraction Compound 2a crystallized in a monoclinic system (P21/a space group) with cell parameters a = 18.6860 (3), b = 11.3037 (2), c = 19.8993(3), b = 112.1897 (10), V = 3891.86 (11) Å3, wR2 (all data) = 0.0407 and R1 = 0.0386 for data with I > 2σ(I) Compound was evaluated for its antimicrobial activity GRAPHICAL ABSTRACT

Synthesis of Trapen Ligand-Based U(IV) and Th(IV) 2-Phosphaethynolate Complexes and Comparison of Covalency with Corresponding Ti(IV) Analogues.

The involvement of the 2-phosphaethynolate anion species with ambident nucleophilic properties serves as an essential protocol for synthesizing oxygen-bound or phosphorus-bound complexes. This work mainly describes the synthesis and characterization of U, Th, and Ti phosphaethynolate complexes featuring a preferential O-coordination fashion. Among these complexes, the first examples of a Ti(IV)-OCP complex 3A, Th(IV)-OCP complex 3B, and U(IV)-OCP complex 3C were assembled by a salt metathesis reaction between M(TrapenTMS)(Cl) (M = Ti, Th, U) and NaOCP(dioxane)2.5 and were all crystallographically characterized. The structural similarity of this series of phosphaethynolate complexes allows us to compare the bonding properties of d- and f-block elements in the corresponding compounds. The well-established density functional theory (DFT) computational method was employed to explore the electronic structures and covalency in M-O bonding, and the results showed a consistent pattern. The calculation result showed that 2-phosphaethynolate complexes exhibited the covalency trend of U-O > Th-O > Ti-O due to the involvement of 5f orbitals.

Unprecedented cleavage of -N-N- bond of ligand and phenyl ring nitration during nitric oxide (NO) reactivity studies: new ruthenium nitrosyl complex and photoinduced liberation of NO

A two-step procedure was used to make the ruthenium nitrosyl complex [Ru(L3)(PPh3)(NO)Cl2] (1a). The product generated when ligand L1 and [Ru(PPh3)3Cl2] reacted to an acidified nitrite solution treatment. Single-crystal X-ray diffraction was used to determine the crystal structure of (1a). Complex (1a) has a {Ru–NO}6 moiety in the Enemark–Feltham notation and was found to be diamagnetic in nature. Photolytic cleavage of metal-bound NO in (1a) was observed under ultraviolet light, and photoreleased free NO was trapped by reduced myoglobin. The amount of photoreleased NO was estimated by the Griess assay. DFT computations were also performed to authenticate the electronic properties of (1a).