SYNTHESE DU FOSTEDIL (4-(2-BENZOTHIAZOLYL) BENZYLPHOSPHONATE DE DIETHYLE) A PARTIR D'IMIDATES N-ACYLES

Fostedil (diethyl 4-(benzothiazol-2-yl) benzylphosphonate) 7 has been synthesized efficiently by treatment of 2-(4-bromomethylphenyl) benzothiazole 6 with triethylphosphite. The latter (6) has been prepared by bromation of benzothiazole 3c. N-acylimidates 1(a–d) react with 2-aminobenzenethiol 2 to lead to the corresponding benzothiazoles 3(a–d) after elimination of primary amide 5. The structure of these products have been unequivocally confirmed by means of IR, ¹H, ¹³C, and ³¹P NMR spectroscopy and mass spectra.     

Synthesis,crystal structure,and antibacterial activity of mononuclear nickel(II) and cobalt(III) Schiff-base complexes

Four new mononuclear complexes, [Ni(L¹)(NCS)₂] (1), [Ni(L²)(NCS)₂] (2), [Co(L¹)(N₃)₂]ClO₄ (3), and [Co(L²)(N₃)₂]ClO₄ (4), where L¹ and L² are N,N′-bis[(pyridin-2-yl)methylidene]butane-1,4-diamine and N,N′-bis[(pyridin-2-yl)benzylidene]butane-1,4-diamine, respectively, have been prepared. The syntheses have been achieved by reaction of the respective metal perchlorate with the tetradentate Schiff bases, L¹ and L², in presence of thiocyanate (for 1 and 2) or azide (for 3 and 4). The complexes have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 are distorted octahedral geometries. The antibacterial activity of all the complexes and their constituent Schiff bases have been tested against Gram-positive and Gram-negative bacteria.     

Zinc(II) and mercury(II) complexes with Schiff bases: syntheses,spectral, and structural characterization

Schiff bases o-vanilidene-1-aminobenzene (HL¹) and o-vanilidene-2-methyl-1-aminobenzene (HL²) lead to the formation of mono- and bis-[(Cl)Zn(L¹)] (1), [(Cl)Zn(L²)] (2), [(Cl)Hg(L¹)] (3), [(Cl)Hg(L²)] (4), [Zn(L¹)₂] (5), [Zn(L²)₂] (6), [Hg(L¹)₂] (7), and [Hg(L²)₂] (8) complexes by reactions of zinc(II) and mercury(II) chlorides in different mole ratio(s). Complexes 1–8 have been characterized by elemental analyses (Zn, Hg, C, H, Cl, and N), melting point and spectral (IR, ¹H-NMR), PXRD, molar conductivity measurement, and TGA. Conductivity measurements suggest non-electrolytes. Structural compositions have been assigned by mass spectral studies. Four-coordinate geometry may be assigned to these complexes tentatively. Structural study reveals that in 1–4 two metal centers are held together by two bridged (μ₂-Cl) chlorides, whereas 5–8 contain two bidentate Schiff-base ligands around one metal-producing monomers.     

The DNA-binding behavior and DFT calculation of ruthenium(II) complexes [Ru(phen)2L](ClO4)2 (L = HMOPIP and MOHPIP)

Two ruthenium(II) complexes, [Ru(phen)₂HMPIP]²⁺ (1) and [Ru(phen)₂MHPIP]²⁺ (2), have been synthesized and characterized by elemental analysis, ESI-MS, and ¹H NMR spectroscopy. The DNA-binding properties of 1 and 2 have been investigated by electronic and emission spectra and viscosity experiments. The results show that both 1 and 2 can bind to DNA in intercalating mode, with 1 exhibiting stronger binding affinity. These were confirmed by the strong hypochromism at IL and MLCT absorption bands in both complexes when DNA was added into solution, and the increase in relative viscosity of CT-DNA in the presence of both complexes. Moreover, the calculated intrinsic binding constant for 1 and 2 from the decay of electronic spectra is 3.82 × 10⁵ and 2.06 × 10⁵ M^?1, respectively. Finally, the effects of the substituent groups on the DNA-binding behavior of ruthenium(II) complexes have also been rationally discussed by computer calculation of density functional theory (DFT) methods.     

New palladium(II) complexes with pyrazole ligands

The pyrazole ligand 3,5-dimethyl-4-iodopyrazole (HdmIPz) has been used to obtain a series of palladium(II) complexes (1–4) of the type [PdX₂(HdmIPz)₂] {X = Cl⁻ (1); Br⁻ (2); I⁻ (3); SCN⁻ (4)}. All compounds have been isolated, purified, and characterized by means of elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H}-NMR experiments, differential thermal analysis (DTA), and thermogravimetry (TG). The TG/DTA curves showed that the compounds released ligands in the temperature range 137–605 °C, yielding metallic palladium as final residue. The complexes and the ligand together with cisplatin have been tested in vitro by MTT assay for their cytotoxicity against two murine cancer cell lines: mammary adenocarcinoma (LM3) and lung adenocarcinoma (LP07).     

Synthesis and thermodynamic studies of the dinuclear adducts between dimethyltin(IV) dichloride with SalenH2 and MII(Salen) complexes in chloroform

A UV-Vis spectrophotometric study of adduct formation of SalenH₂ (1) and M^II(Salen), where M?=?Mn (2), Fe (3), Co (4), Ni (5) and Cu (6) as donors with Me₂SnCl₂ as acceptor have been investigated in chloroform. Adducts (1a–6a) have been characterized by ¹H, ¹³C and ¹¹⁹Sn NMR, IR and electronic spectroscopy and microanalysis. Formation constants and thermodynamic parameters were measured for 1 : 1 and 2 : 1 adducts at various temperatures (T?=?278 to 308 K). The data refinement was carried out with the SQUAD 84 program. The trend of formation constants of M^II(Salen) complexes with Me₂SnCl₂ follows the order: Mn>Fe>Cu>Co>Ni. The formation constants for the free 1 and M^II(Salen) with Me₂SnCl₂ changes according to the following trend: M^II(Salen)>SalenH₂     

Synthesis,characterization, and DNA-binding of [Co(phen)2(CPIA)]3+, [Co(phen)2(BIP)]3+, and [Co(phen)2(CIP)]3+

Three ligands, 2-(3-(carboxymethyl)-1,10-phenanthroline-[5,6-d]imidazole-1-yl)acetate (CPIA), 2-(benzo[d][1,3]dioxol-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (BIP), and 2-(9H-carbazol-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (CIP), and their complexes, [Co(phen)₂(CPIA)]³⁺ (1) (phen = 1,10-phenanthroline), [Co(phen)₂(BIP)]³⁺ (2), and [Co(phen)₂(CIP)]³⁺ (3), have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, cyclic voltammetry, and viscosity measurements. The three complexes bind to DNA through an intercalative mode, and the size and shape of the intercalative ligands have significant effects on the binding affinity of complexes to CT-DNA.     

Square planar complexes of Cu(II) and Ni(II) with N<Subscript>2</Subscript>O donor set of two Schiff base ligands: synthesis and structural aspects

Abstract Two new square planar Cu(II) and Ni(II) complexes, [CuL¹(NCO)] (1) and [NiL²(N₃)] (2) have been synthesized with two different tridentate N₂O donor Schiff base ligands L ¹ H (1:1 condensation product of benzoylacetone and 2-diethylaminoethylamine) and L ² H (1:1 condensation product of benzoylacetone and 2-dimethylaminoethylamine), respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal, and single crystal X-ray diffraction studies. Structural studies reveal that in both the complexes metal centers have square planar environment with N₂O donor set of Schiff base ligands and terminal pseudohalide anions (isocyanate for 1 and azide for 2) at four coordination sites of square plane. Graphical abstract Square planar complexes of Cu(II) and Ni(II) with N ₂ O donor set of two Schiff base ligands: synthesis and structural aspects Subhra Basak, Soma Sen, Samiran Mitra, C. Marschner, W. S. Sheldrick Two new square planar Cu(II) and Ni(II) complexes, [CuL¹(NCO)] (1) and [NiL²(N₃)] (2) have been synthesized with two different tridentate N₂O donor Schiff base ligands L ¹ H and L ² H respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal and single crystal X-ray diffraction studies.      

Palladium(II) complexes containing cytokinins derived from 6-benzylaminopurine

A series of palladium(II) complexes of general formula [Pd(LH⁺)Cl₃] (1–12) containing 6-benzylaminopurine derivatives has been prepared [L?=?6-(2-methoxybenzylamino)purine (1), 6-(3-methoxybenzylamino)purine (2), 6-(4-methoxybenzylamino)purine (3), 6-(2-hydroxy-benzylamino)purine (4), 6-(3-hydroxybenzylamino)purine (5), 6-(4-hydroxybenzylamino) purine (6), 6-(2-fluorobenzylamino)purine (7), 6-(3-fluorobenzylamino)purine (8), 6-(4-fluorobenzylamino)purine (9), 6-(2-chlorobenzylamino)purine (10), 6-(3-chlorobenzylamino) purine (11) and 6-(4-chlorobenzylamino)purine (12)]. The compounds have been characterized by elemental analysis, IR, ES+ MS and ¹H- and ¹³C-NMR spectroscopy, and two of them, 6 and 12, also by TG/DSC analyses. The complexes have been screened in vitro against the four human tumour cell lines G-361, HOS, K-562 and MCF7.     

Zinc(II) and lead(II) coordination polymers built by 3-(4-carboxyphenylhydrazono)pentane-2,4-dione

Two coordination polymers [Zn(L)₂(4,4′-bipy)₂] _n (4,4′-bipy = 4,4′-bipyridine) (1) and [Pb(η ²-L)(µ₃-η ²-CH₃COO)(H₂O)] _n (2) have been prepared by the reaction of 3-(4-carboxyphenylhydrazono)pentane-2,4-diketone (HL) with zinc(II) or lead(II) in solution. Polymer 1 shows an infinite zigzag chain, in which Zn(II) are linked by 4,4′-bipy bridges with carboxylate of L^? monodentate to Zn(II). In 2, Pb(II) are bridged by tetradentate µ₃-η ²-CH₃COO^? to form a linear 1-D chain, and each Pb(II) is chelated by carboxylate of L^?. Their molecular structures have been characterized by elemental analysis, infrared, and single-crystal X-ray diffraction. Thermal and fluorescent properties of the two complexes have been investigated.     

Mn(III) and Cu(II) complexes of 1-((3-(dimethylamino)propylimino)methyl) naphthalen-2-ol): Synthesis,characterization, catecholase and phenoxazinone synthase activity and DFT-TDDFT study

Two new complexes, [MnL₂](ClO₄) (1) and [CuL₂] (2) (where LH = (E)-1-((3-(dimethylamino)propylimino)methyl)naphthalen-2-ol), have been synthesized and characterized by spectroscopic techniques and their molecular structures are established by single-crystal X-ray diffraction study. Complex 1 adopts an octahedral geometry around the central manganese atom which is in + 3 oxidation state, whereas in complex 2, the Cu⁺² ion preferred a square pyramidal environment around it through the ligand donor atoms. Both complexes were tested for catecholase and phenoxazinone synthase activity. Complex 1 catalyzes the oxidation of 3,5-ditertiary-butyl catechol with a k_cat value of 6.8424 × 10² h^?1 in acetonitrile whereas the same for complex 2 is 3.7485 × 10² h^?1 in methanol. Phenoxazinone synthase activity was shown only by complex 2 having k_cat = 74.225 h^?1. Structures of both the title complexes have been optimized by means of DFT calculations. Experimental electronic spectra of the complexes have been corroborated by TDDFT analysis. Electrochemical investigations by means of cyclic voltammetry have been carried out to study the electron transfer processes in the complexes.     

Effect of the ancillary ligands on the binding of ruthenium(II) complexes [Ru(dmp)2(MCMIP)]2+ and [Ru(dmb)2(MCMIP)]2+ with DNA

Two polypyridine ruthenium(II) complexes, [Ru(dmp)₂(MCMIP)]²⁺ (1) (MCMIP = 2-(6-methyl-3-chromonyl)imidazo[4,5-f][1,10]-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline) and [Ru(dmb)₂(MCMIP)]²⁺ (2) (dmb = 4,4′-dimethyl-2,2′-bipyridine), have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR. The DNA-binding behaviors of these complexes were investigated by electronic absorption titration, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The results show that 1 and 2 effectively bind to CT-DNA; the DNA-binding affinities are closely related to the ancillary ligand.     

Synthesis,crystal structure and antibacterial activity of manganese(III) and cobalt(III) complexes containing pentadentate Schiff bases of a common amine and thiocyanate

Abstract

Four new mononuclear Schiff base manganese(III) and cobalt(III) complexes viz. [Mn(L¹)(NCS)] (1), [Mn(L²)(NCS)] (2), [Co(L³)(NCS)] (3), and [Co(L⁴)(NCS)]·0.5CH₃OH·0.5H₂O (4), containing thiocyanate as a common pseudohalide ion are reported. The pentadentate Schiff base ligands H₂L¹, H₂L², H₂L³, and H₂L⁴ were obtained by the condensation of substituted salicylaldehydes with N-(3-aminopropyl)-N-methylpropane-1,3-diamine. The syntheses of the complexes have been achieved by the reaction of manganese(II) perchlorate or cobalt(II) perchlorate with the respective Schiff bases in the presence of thiocyanate in methanol medium. Complexes 1–4 have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1–4 adopt nearly similar structures containing the MN₄O₂ (M?=?Mn, Co) chromophore in which each central M(III) ion adopts a distorted octahedral geometry. Weak intermolecular H-bonding interactions are operative in these complexes to bind the molecular units. The antibacterial activity of 1–4 and their constituent Schiff bases has been tested against some common bacteria.     

Preparation,Isolation and Characterization of all of the Regioisomeric 61, 6N-Bis-O-(Monomethoxytrityl) and-(Dimethoxytrityl) Derivatives of Cyclomalto-Olgosaccharides

Abstract

Regioisomeric 6¹, 6ⁿ-bis-O-(monomethoxytrityl) or 6¹, 6ⁿ-bis-O-(dimethoxytrityl) cyclomaltohexaose, -cyclomaltoheptaose (n = 2-4), and -cyclomaltooctaose derivatives (n = 2-5) were prepared by the reaction of cyclomaltohexaose (1, cG₆, αCD), cyclomaltoheptaose (11, cG₇, βCD) or cyclomaltooctaose (21, cG₈, γCD) and 4-monomethoxytrityl chloride or 4,4′-dimethoxytrityl chloride in pyridine. Products were isolated by HPLC. The regiochemical determination of these positional isomers was done by converting these compounds to the respective 6¹, 6ⁿ-bis-O-(tert-butyldimethylsilyl) derivatives¹ whose structures have been already established.     

Synthesis and Characterization of a Novel Phosph(V)azane-Tin(IV) Complex

Abstract

The reaction of bis(anilino)phosphine oxide (C₆H₅NH)₂P(O)H, 1 with Bu₂ ⁿSnCl₂ in the presence of an excess of triethylamine (TEA) in dry tetrahydrofurane (THF) yields the novel N,O-bonded tin complex Bu₂ ⁿSn[NPh(O)P(H)NPh(HNEt₃)]₂, 2. TEA is used as a base to deprotonate the phosphazane ligand and is separated as Et₃NH⁺Cl^?, whereas HTEA⁺ exists in the final product 2 and act as a charge balancing and H-bond structure–directing agent. This new compound has been fully characterized by means of IR, MS, and multinuclear (¹H, ³¹P, and ¹¹⁹Sn NMR) spectroscopy.     

1-(2-Hydroxyethyl)-5-mercapto-1H-tetrazole as ligand in Cu(I) complexes with or without X-ions (X = Cl,Br, I): synthesis,crystal structures and properties

Four Cu(I) complexes with 1-(2-hydroxyethyl)-5-mercapto-1H-tetrazole (Hhmt) as a ligand, [Cu(hmt)]_n (1), [Cu₂Cl(hmt)]_n (2), [Cu₄Br(hmt)₃]_n (3), and [Cu₄I(hmt)₃]_n (4), have been synthesized. In 1–4, hmt adopts a μ₄-η^1?:^? η^1?:^? ηS² coordinate mode to join the adjacent Cu(I) ions, which form different two-dimensional (2-D) structures. In 1, the neighboring four Cu(I) atoms are connected by μ₄-hmt to form a 2-D structure. In 2, the Cu(I) ions are firstly connected with Cl ions to form a 1-D [Cu₄Cl₂] subunit chain, which then have been bridged by hmt to form a 2-D structure. However, the inorganic [Cu₄Br] and [Cu₄I] motifs are respectively connected by hmt to form 2-D structures in isostructural 3 and 4. In addition, the fluorescent properties and the thermal stability properties of 1–4 have been investigated.     

Three new coordination complexes of cobalt(III), manganese(II), and copper(II) with N,N,O-donor hydrazone ligands: syntheses and structural characterizations

Three new coordination complexes, 2{[Co(L¹)₂]ClO₄} · 0.5CH₃OH (1), [Mn(L²)₂] (2), and [Cu(HL²)(L²)]ClO₄ · 2H₂O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL¹, 2-acetylpyridine-salicyloylhydrazone, and HL², 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV–Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L¹)₂]⁺ units and 2 consists of a neutral [Mn(L²)₂] molecule while 3 consists of a cationic [Cu(HL²)(L²)]⁺ unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.     

Synthesis,structure, and catalytic activity of lanthanide Gd(III) and La(III) complexes with N-(cyclohexyl)isopropyl amidate ligand

Two new lanthanide amidate complexes, {Gd₂[Cy(NCO)ⁱPr]₆} (1) and {La₂[Cy(NCO)ⁱPr]₆[Cy(HNCO)ⁱPr]} (2) (ⁱPr = isopropyl, Cy = cyclohexyl), have been synthesized in good yields by silylamine elimination reaction between Gd[N(SiMe₃)₂]₃ or La[N(SiMe₃)₂]₃ and N-(cyclohexyl)isopropyl amide. Complexes 1 and 2 have been characterized by NMR, elemental analyzes, and X-ray diffraction. The molecular structures of {[Cy(NCO)ⁱPr]Gd[μ₂-Cy(NCO)ⁱPr]₃Gd[Cy(NCO)ⁱPr]₂} (1) and {[Cy(NCO)ⁱPr]La[μ₂-Cy(NCO)ⁱPr]₃La[Cy(NCO)ⁱPr]₂[Cy(HNCO)ⁱPr]} (2) exhibit a dimer structure with three μ₂-O bridging bonds that look like a windmill. Additionally, 2 formed an intramolecular N–H···O hydrogen bond via a neutral amide. The catalytic properties of 1 and 2 for ring-opening polymerization (ROP) of ε-caprolactone have been studied. The results show that 1 and 2 are efficient catalysts for the ROP of ε-caprolactone.     

NMR studies of 4(3H)-quinazolinones and 4(3H)-quinazolinethiones

Summary Unambiguous¹H and¹³C NMR assignments for 4(3H)-quinazolinones1–6 and their corresponding 4-thiones7–12 have been made. This resulted in the revision of the previous assignments for the two benzenoid carbons (C-5 and C-8) of quinazolinones1,2,4, and5. Thionation of the nucleophilic amides1–6 has been found to cause a distinct change in the¹³C chemical shift of particularly C-4, but also of those of C-4a, C-5, and C-8a. One-bond and several long range heteronuclear coupling constants for the compounds have also been measured.

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Kernresonanzspektroskopie von 4(3H)-Chinazolinonen und 4(3H)-Chinazolinthionen

Zusammenfassung Die¹H- und¹³C-NMR-Spektren der 4(3H)-Chinazolinone1–6 und ihrer entsprechenden 4-Thione7–12 wurden zugeordnet. Dabei zeigte sich, daß eine frühere Zuordnung der beiden benzoiden Kohlenstoffe (C-5 und C-8) der Chinazolinone1,2,4 und5 falsch war. Ersatz des Sauerstoffs durch Schwefel in den nukleophilen Amiden1–6 führt insbesondere für C-4, aber auch für C-4a, C-5 und C-8a zu einer deutlichen Änderung der chemischen Verschiebung. Heteronukleare Kopplungskonstanten über eine und über mehrere Bindungen wurden bestimmt.

     

Exploratory syntheses,crystal structures,and properties of two new 3-D coordination polymers of Mn(II) and Fe(II) with (54.62) (510.63.7.8) topological spaces

Solvothermal reactions of terphenyl-2,5,2′,5′-tetracarboxylic acid (H₄qptc) and M^II (M = Mn, Fe) in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) afford two new coordination polymers, [M(qptc)(dppe-O)] _n (M?=?Mn (1), Fe (2)) (1,2-bis(diphenylphosphoryl)ethane?=?dppe-O). The structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR, TGA, and magnetism. The M^II in 1 and 2 are linked by qptc^4? to form 2-D layers, which are further connected via the oxidized dppe (dppe-O) exhibiting a (4,6)-connected network with the (5⁴.6²)(5¹⁰.6³.7.8) topology.