Syntheses,structures and properties of Zn(II) and Co(II) complexes of N-benzesulfonyl-l-glutamic acid ligand

The reaction of N-benzesulfonyl-l-glutamic acid (Bs-glu) with Zn(CH₃COO)₂ · 2H₂O or Co(CH₃COO)₂ · 4H₂O in the presence of imidazole (Im) produced two novel complexes [Zn(Im)₂(Bs-glu)]_n (1) and [Co(Im)₂(Bs-glu)]_n (2). Both of the complexes exhibit similar one-dimensional structural motif and coordination environment. Bs-glu adopts the bis-monodentated coordination mode linking two adjacent metal ions. The complex 1 shows intense photoluminescence in the solid state. Magnetic measurements for 2 show that the exchange interaction of the two Co(II) ions is antiferromagnetic.     

Syntheses of All Stereoisomers of Goniodiol from Yeast-Reduction Products and Their Antimicrobiological Activity

All stereoisomers of goniodiol were synthesized from yeast-reduction products. The C-6 chiral centers were converted from the chiral centers of the yeast-reduction products. Stereoselective conversion of the alkene, which had been prepared from the yeast-reduction product, to glycol constructed the C-7 and C-8 stereochemistry. (+)-Goniodiol and 7-epi-(+)-goniodiol showed the highest antibacterial activity (MIC, 3.1 mM) against Yersinia intermedia.     

Syntheses, structures and photoluminescence properties of cadmium(II) and zinc(II) complexes with pyridinylcarboxamide-containing ligand

Four new coordination complexes [Cd(DPBA-3)₂(H₂O)₂](ClO₄)₂·2H₂O (1), [Cd(DPBA-3)(DMF)(NO₃)₂]·DMF (2), [Cd₃(DPBA-3)₂(SCN)₆]·2DMF·4H₂O (3) and [Zn(DPBA-3)(SCN)₂] (4) [DPBA-3 = N,N′-di(pyridin-3-yl)pyridine-3,5-dicarboxamide] have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. Complexes 1, 3 and 4 exhibit three different types of one-dimensional (1D) chain structures constructed by the metal ions and DPBA-3 ligands, and the Cd(II)-DPBA-3 1D chains in 3 are further linked by bridging SCN⁻ ligands to afford a three-dimensional (3D) framework. Complex 2 possesses a (6,3) two-dimensional (2D) layer structure. In 1-4, the hydrogen bonds involving the amide groups play important role to stabilize the resultant frameworks. The photoluminescence properties of the DPBA-3 and the complexes were studied in the solid state at room temperature.     

Syntheses, Characterization, and Antitumor Activities of Platinum(II) and Palladium(II) Complexes with Sugar-Conjugated Triazole Ligands

Four platinum(II) and palladium(II) complexes with sugar-conjugated bipyridine-type triazole ligands, [Pt(II) Cl(2) (AcGlc-pyta)] (3), [Pd(II) Cl(2) (AcGlc-pyta)] (4), [Pt(II) Cl(2) (Glc-pyta)] (5), and [Pd(II) Cl(2) (Glc-pyta)] (6), were prepared and characterized by mass spectrometry, elemental analysis, (1) H- and (13) C-NMR, IR as well as UV/VIS spectroscopy, where AcGlc-pyta and Glc-pyta denote 2-[4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl]ethyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside (1) and 2-[4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl]ethyl β-D-glucopyranoside (2), respectively. The solid-state structure of complex 6 was determined by single-crystal X-ray-diffraction analysis. These complexes exhibited in vitro cytotoxicity against human cervix tumor cells (HeLa) though weaker than that of cisplatin.     

Pyrazolato-bridged 1-D Co(II) coordination polymer and dinuclear Ni(II) and Cu(II) complexes: Syntheses, crystal structures and magnetic properties

Three complexes of composition [Co₃(Hdcp)₂(phen)₃(H₂O)₂]_n · nH₂O (1), [Ni₂(Hdcp)₂(H₂O)₄](Im)₂ (2) and [Cu₂(Hpca)₂(H₂O)₂(Im)₂] (3) (H₃dcp = 3,5-pyrazoledicarboxylic acid, H₂pca = 1H-pyrazole-5-carboxylic acid, Im = imidazole and phen = 1,10-phenanthroline) have been synthesized via hydrothermal reactions and their structures have been characterized. Complex 1 is mainly constructed by Hdcp and ancillary ligand 1,10-phenanthroline and exhibits one-dimensional linear chain structure. Complexes 2 and 3 are pyrazolato-bridged dinuclear complexes. The ancillary imidazole ligand was not involved in the coordination and stacked to the lattice of the complex in 2. In the process of synthesis 3, imidazole ligand was coordinated to the metal centre; with one of the carboxylic group of the H₃dcp ligand was eliminated to form [Cu₂(Hpca)₂(H₂O)₂(Im)₂] (3) in situ. The results of magnetic susceptibility measurements indicate that there exist antiferromagnetic interactions between Co(II) and Ni(II) centres in compounds 1 and 2, respectively.     

Syntheses, crystal structures and properties of Cd(II) and Co(II) complexes with 4,4′-dipyridylsulfide ligand

Two new coordination polymers [Cd(dps)₂Cl₂] (1) and [Co(dps)₂(H₂O)₂]·(abs)₂(H₂O)₂ (2) (dps = 4, 4′-dipyridylsulfide, Habs = 4-amino benzenesulfonic acid) have been synthesized under similar conditions and characterized by elemental analysis, fluorescence spectra and single crystal X-ray diffraction. Compound 1 displays a dps-bridged 2D puckered, grid-like layer, which is further linked by C-H?Cl hydrogen bonds to form a 3D supramolecular architecture. Compound 2 shows a dps-bridged double-stranded chain structure, which is extended by N-H?O and O-H?O hydrogen bonds generating a 3D network. Solid-state fluorescence results reveal that both complexes can emit strong emission bands, at 467 nm and 518 nm for 1 and 344 nm for 2, respectively. Magnetic measurements show that there are weak antiferromagnetic interactions between the adjacent Co(II) ions in 2.     

Syntheses and structures of photochromic molybdenum(II) and rhodium(II) complexes with 1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene

Four novel Mo(II) and Rh(II) complexes with cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (cis-dbe) or closed-dbe were synthesized and characterized. Employing [M(O₂CCF₃)₄] (M = Mo, Rh) with cis-dbe or closed-dbe afforded complex [Mo₂(O₂CCF₃)₄(cis-dbe)](benzene) (1), [Rh₂(O₂CCF₃)₄(cis-dbe)](benzene) (2), [{Mo₂(O₂CCF₃)₄}₂(closed-dbe)] (3), and [Rh₂(O₂CCF₃)₄(closed-dbe)](p-xylene) (4). The structures of four metal complexes were revealed by X-ray crystallographic analyses and the correlation between the crystal structures and the photochromic performance was discussed. In all complexes, two cyano groups of the ligand bridged two dimetal carboxylates to give a 1-D zigzag infinite chain structure. Upon irradiation with 405 nm light, complex 1 turned into reddish purple from yellow, and the color reverted to initial yellow on exposure to 563 nm light, indicating the reversible cyclization/ring-opening reaction in the crystalline phase. However, the Rh(II) complex 2 did not display similarities in reaction induced by light, which is attributable to the lower ratio of photoactive anti-parallel conformers compared with complex 1 and coordination effect of metal ions on photochromism of diarylethenes. The complexes of Rh(II) ions did not exhibit the expected reversible photoinduced behavior.     

Syntheses and crystal structures of three Mn(II) complexes with 2-hydroxynicotinate

Three new Mn(II) complexes [Mn(HnicO)₂(H₂O)₂] (1), [Mn₂(HnicO)₂SO₄(H₂O)₂]_n (2), and [NaMn(HnicO)₃]_n (3) (H₂nicO = 2-hydroxynicotinic acid) have been synthesized and determined by X-ray diffraction. For complex 1, the mononuclear units with two bidentate HnicO⁻ ions and two water molecules are assembled into a 3D architecture via hydrogen bonding and π-π interactions. For 2, Mn(II) ions are connected by μ₃-HnicO⁻ and bridging ligands, producing a 2D (6,3) coordination network. For 3, binuclear Na(I)-Mn(II) units with three carbonyl oxygen bridges are interlinked by carboxylate groups, resulting in a 3D 6-connected coordination network with distorted α-Po topology. The magnetic properties of 2 are discussed.     

Syntheses, structures and magnetic properties of Mn(II), Co(II) and Ni(II) metal-organic frameworks constructed from 1,3,5-benzenetricarboxylate and formate ligands

Three compounds, [(CH₃)₂NH₂][M₃(BTC)(HCOO)₄(H₂O)]·H₂O (M = Mn (1), Co (2), Ni (3), H₃BTC = 1,3,5-benzenetricarboxylic acid), were synthesized under hydrothermal conditions and were characterized by single crystal and powder X-ray diffraction, IR spectra, elemental analysis, coupled TG-MS and magnetic measurements. Compounds 1-3 are isostructural analogues and crystallize in monoclinic space group P2₁/c. Each metal ion in these compounds connects to six oxygen atoms to form a MO₆ octahedron. Six MO₆ octahedra link to each other to form a corner-shared hexameric M₆ cluster, which is linked by BTC ligands to form two-dimensional layers. The two-dimensional layers are further connected by formic ions to form a three-dimensional network with channels, where (CH₃)₂NH₂⁺ ions and water molecular are located. Magnetic measurements indicate that anti-ferromagnetic ordering occurs at low temperature for these compounds.     

A Stereoselective Synthesis of Antimycinone A3 and Its Stereoisomers

Antimycinone A₃, which is a neutral fragment of mild alkaline hydrolysate of antimycin A₃, and its stereoisomers were synthesized stereoselectively from methyl trans-2-n-butylpent-3-enoate or methyl cis-2-n-butylpent-3-enoate, and natural antimycinone A₃ was proved to possess Hα-Hβ and Hβ-Hγ trans configuration.     

Syntheses, characterizations and crystal structures of four zinc(II) and cadmium(II) complexes constructed by ligand bearing poly-coordination atoms

Treatment of 3-(4-carboxyphenylhydrazono)pentane-2,4-dione (HL) with transition metal ions afforded four novel complexes, [Zn(L)(μ₂-OOCCH₃)(H₂O)]_n (1), [Zn(L)₂(MeOH)₄] (2), {[Cd₄(η²-L)₄(μ₂-η²-L)₄(H₂O)₄(MeOH)₂]·MeOH} (3) and [Cd(η²-L)(μ₂-η²-OOCCH₃)(H₂O)₂]_n (4). Their crystal structures have been characterized by single-crystal X-ray crystallography. In polymer 1, the acetate anions bridge the Zn(II) ions forming an infinite one-dimensional (1-D) chain with L⁻ units acting as monodentate ligands in the side chain. In mononuclear complex 2, two L⁻ ligands act as monodentate fashion to coordinate to the Zn(II) ion. In its solid-state structure, [Zn(L)₂(MeOH)₄] groups are joined together by hydrogen bonds forming a three-dimensional (3-D) supramolecular network. In tetranuclear complex 3, four Cd(II) ions are linked by four μ₂-η²-L⁻ ligands, and chelated by another four L⁻ ligands, respectively. In polymer 4, the acetate anions bridge the Cd(II) ions leading to a 1-D chain containing chelating L⁻ units in the side chain.     

Syntheses of PbO nano-powders using new nano-structured lead(II) coordination polymers

Nano-structures of two new Pb(II) coordination polymers, [Pb(DPAcO)₂]_n (1) and [Pb(MPAcO)₂]_n (2), HDPAcO = diphenyl acetic acid and HMPAcO = monophenyl acetic acid} were synthesized by a sonochemical method. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compound 2 was structurally characterized by single crystal X-ray diffraction. The crystal structure of the compound 2 consists of one-dimensional polymeric units of [Pb(MPAcO)₂] and shows the coordination number in the Pb^II ions is six. The thermal stability of compounds 1 and 2 were studied by thermal gravimetric and differential thermal analyses and shows that nanostructures of compounds 1-2 are somewhat less stable then their bulk materials. PbO nano-powders were obtained by calcinations of the nano-structures of compounds 1 and 2 at 400 °C.     

Syntheses,characterization and DNA-binding studies of ruthenium(II) terpyridine complexes: [Ru(tpy)(PHBI)]2+ and [Ru(tpy)(PHNI)]2+

Two novel tridentate ligands, 2-(2-benzimidazole)-1,10-phenanthroline (PHBI) and 2-(2-naphthoimidazole)-1,10-phenanthroline (PHNI), and their heteroleptic complexes [Ru(tpy)(PHBI)](ClO(4))(2).2H(2)O (1) and [Ru(tpy)(PHNI)](ClO(4))(2).H(2)O (2) (tpy=2,2':6',2"-terpyridyl) have been synthesized and characterized by elemental analysis, mass spectra, 1H NMR, and electronic spectroscopy. The electrochemical behaviors of the two novel complexes were studied by cyclic voltammetry. The DNA-binding properties of the two complexes were investigated by spectroscopic methods and viscosity measurements. The results indicated that the two complexes interact with DNA in different binding modes. Complex 1 may bind to DNA via electrostatic interaction, while complex 2 binds to DNA by partial intercalation via the extended naphthyl ring into the base pairs of DNA.     

Four novel Co(II) and Mn(II) coordination polymers with triazolyl derivate: Syntheses, crystal structures and magnetic properties

Four novel coordination polymers, one-dimensional chains [M(PTE)₂(N₃)₂]_n (M = Mn for 1 and Co for 2), and two-dimensional layers [M(PTE)₂(dca)₂]_n (M = Mn for 3 and Co for 4) (PTE = 1-(2,4-difluorophenyl-2-(1H-1,2,4-triazol-1-yl)ethanone, dca = dicyanamide anion, N(CN)₂⁻), have been synthesized under mild ambient conditions and structurally characterized by single crystal X-ray diffraction. In all four crystal structures, the metal atoms adopt octahedral coordination geometry with six nitrogen atoms from two monodentate PTE ligands and four azido (or dca) bridging ligands. The crystal structures of 1 and 2 are isostructural 1-D polymeric chains, alternatively linked by double end-on and double end-to-end azido bridges. However, the bent dca ligands as bidentate μ₂-1,5 bridging ligands interlink the octahedral metal units to lead to 2-D (4,4) grid networks in 3 and 4. Temperature-dependent magnetic measurements in 2-300 K have been performed for these four polymers, and suggest alternative ferro- and antiferromagnetic couplings for end-on and end-to-end azido bridges in 1, and the dominant ferromagnetic coupling in 2, respectively. Both polymers 3 and 4 show weak antiferromagnetic exchanges through the μ₂-1,5-dca bridges. The effects of auxiliary coligands on the structure and the nature of these magnetic exchanges are discussed in the light of the crystal structures in detail.     

Syntheses, crystal structure and cytotoxicity of diamine platinum(II) complexes containing maltol

The cationic complexes (1,2-diaminoethane)(maltolato)platinum(II) ([Pt(en)(ma)]+) and (1R,2R-1,2-diaminocyclohexane)(maltolato)platinum(II) ([Pt(R,R-DACH)(ma)]+) have been prepared and the structure of [Pt(R,R-DACH)(ma)]NO3 has been determined by single crystal X-ray diffraction. The geometry of the metal in [Pt(R,R-DACH)(ma)]NO3 is essentially square planar and the maltolate ligand has a geometry similar to other chelate complexes involving this ligand. The cytotoxicities of the compounds have been assessed in the human cell lines HeLa and K562 and the IC50 values are approximately 32 microM in HeLa cells and 26 microM in K562 cells. In these cell lines the cytotoxicity of cisplatin is higher than the maltolate complexes by a factor of 2 to 3 whereas the cytotoxicity of carboplatin is lower than the maltolate complexes.     

Syntheses and structures of mononuclear manganese(II) complexes bearing bis(1-methylimidazol-2-yl)ketone ligands

The ligand bis(1-methylimidazol-2-yl)ketone (bik) (1) was applied in the synthesis of mononuclear manganese(II) complexes. The complexes [Mn(bik)₂Cl₂] (2), [Mn(bik)₂(OH₂)Br]Br × H₂O (3b) and [Mn(bik)₃](ClO₄) (4) were characterised by X-ray crystallography, ESR and UV-Vis methods.     

Tetranuclear mixed-valence Co(II/III) and binuclear Ni(II) complexes incorporating hydroxyl-rich ligand: Syntheses, structures and magnetic properties

Three complexes of composition [Co₂^IICo₂^III(H₂hbhpd)₂(H₄hbhpd)₂(H₂O)₂]Cl₂(CH₃OH)₄ (1), [Co₂^IICo₂^III(H₂hbhpd)₂(H₄hbhpd)₂(H₂O)₂](NO₃)₂(CH₃OH)₄ (2) and [Ni₂(H₄hbhpd)₂(NO₃)](NO₃)(CH₃OH)_1.5 (3) (H₅hbhpd = 2-(2-hydroxy-benzylamino)-2-hydroxymethyl-propane-1,3-diol) have been synthesized and their structures have been characterized. Complexes 1 and 2 are mixed-valence cobalt clusters and display face-sharing monovacant dicubane structures. In the complexes 1 and 2, one of the three alkyl hydroxyl groups of H₅hbhpd ligand is deprotonated instead of deprotonation of phenyl hydroxyl group; thus monoanionic H₄hbhpd⁻ ligand displays novel η³, η¹, η¹, μ₃ coordination mode. Complex 3 is binuclear, and the two metal centers of 3 are bridged by two deprotonated phenyl hydroxyl oxygen atoms and iso-orthogonalized by a nitrato group in η¹η¹-O,O′ coordination fashion. Variable-temperature solid-state dc magnetization studies have been performed in the temperature range 2-300 K for compounds 1 and 3. Antiferromagnetic interactions were determined for 1 and ferromagnetic couplings were found for 3.     

Dinuclear alkoxo-bridged copper(II) coordination polymers: Syntheses, structural and magnetic properties

The alkoxo-bridged dinuclear copper(II) complexes [Cu₂(ap)₂(NO₂)₂] (1), [Cu₂(ap)₂(C₆H₅COO)₂] (2) and [Cu₂(ap)₂μ-1,3-C₆H₄(COO)₂(dmso)₂]·dmso (3) (ap = 3-aminopropanolato and dmso = dimethyl sulfoxide) have been synthesized via self-assembly from copper(II) perchlorate, 3-aminopropanol as main chelating ligand and nitrite and isophthalate anions as spacers and benzoate anion as auxiliary ligand. Complexes 1 and 3 crystallize as 2D and 1D coordination polymers, respectively, and their structures consist of dinuclear [Cu₂(ap)₂]²⁺ units connected with nitrite and isophthalate ligands. The adjacent dinuclear units of 2 and 1D polymers of 3 are further connected by hydrogen bonds resulting in the formation of 2D layers. The variable temperature crystallographic measurements of 1 at 100, 173 and 293 K indicate the static Jahn-Teller distortion with librational disorder in the nitrite group. Experimental magnetic studies showed that complexes 1-3 exhibit strong antiferromagnetic couplings. The values of the magnetic exchange coupling constant for 1-3 are well reproduced by the theoretical calculations.     

Syntheses and structural studies of platinum(II) complexes of O-methylselenomethionine and related ligands

The complexes dichloro[2-(phenylselanyl)ethanamine]platinum(II), dichloro[2-(benzylselanyl)ethanamine]platinum(II) and dichloro(O-methylselenomethionine)platinum(II) have been prepared and the structure of dichloro(O-methylselenomethionine)platinum(II) has been determined by single crystal X-ray diffraction. The Pt(II) is in a square planar environment and is coordinated by two cis chloride ligands and a chelating O-methylselenomethionine ligand. The cytotoxicities of the compounds have been assessed in the human cell lines HeLa and K562 and they are at least threefold less toxic than cisplatin in both cell lines.     

Platinum(II) complexes with aryl tellurols and diaryl ditellurides: Syntheses and spectral investigations

Arytellurol complexes [PtCl(TeAr)(PPh₃)₂] (I) and [Pt(TeAr)₂(PPh₃)₂] (II) are readily obtained from cis-[PtCl₂(PPh)₃)₂] and NaTeAr (Ar = C₆H₅, 4-CH₃OC₆H₄ and 4-CH₃CH₂OC₆H₄) in ethanolbenzene at room temperature. ³¹P NMR spectra of (I) and (II) indicate their trans configuration in solution. Metathetical reactions between I (Ar = 4-CH₃OC₆H₄) and NaX (X = I, Br, SCN) occur in methanol to give [Pt(X)(TeC₆H₄OCH₃-4)(PPh₃)₂]. ¹H NMR shows that equimolar proportions of NaTeC₆H₅, NaTeC₆H₄OCH₂CH₃-4 and cis-[PtCl₂(PPh₃)₂] give a mixture of three complexes: II, Ar = C₆H₅; II, Ar = 4-CH₃CH₂OC₆H₄; and [Pt(TeC₆H₅)(TeC₆H₄OCH₂CH₃-4)(PPh₃)₂]. Polymeric complexes [PtCl(TeAr)]_n (III) and [Pt(TeAr)₂]_n (IV) result from reaction between K₂[PtCl₄] and NaTeAr in aqueaous ethanol. They react with excess of PPh₃ in CDCl₃ to yield monomeric complexes I and II respectively which were characterized in situ by ¹H and ³¹P NMR of the reaction mixtures. IR spectra indicate the presence of bridging chloride ligands in III. An alternating chloride and tellurol bridged chain structure for III and a tellurol bridged for IV have been proposed. Reaction between equimolar amounts of III and PPh₃ in dichloromethane yielded a tellurol bridged dimeric complex [PtCl(μ-TeAr)(PPh₃)]₂ (V) with terminal chloride ligand as suggested by IR study. Ethanolic solutions of diarylditellurides also react readily with an aqueous solution of K₂[PtCl₄] at 10 °C to give complexes for which the structure trans-[PtCl₂(ArTeTeAr)₂] (VI) is suggested from their elemental analyses, IR, Raman (in one case only), ¹H, ¹²⁵Te (in one case only), and ¹⁹⁵Pt NMR spectra and reactions with triphenylphosphine which liberated free ditellurides. At 40 °C or above the same ditellurides form polymeric complexes III with K₂[PtCl₄] in aquaeous ethanol.