Single Crystal X-ray Determination Research Articles

Synthesis, Crystal Structures and Catalytic Property of Oxidovanadium(V) Complexes with N’-(4-Oxopentan-2-ylidene)nicotinohydrazide and 4-Bromo-N’-(4-oxopentan

A pair of structurally similar oxidovanadium(V) complexes with the general formula [VOLL’], with the hydrazone compounds N' -(4-oxopentan-2-ylidene)nicotinohydrazide (H 2 L 1 ) and 4-bromo- N' -(4-oxopentan-2-ylidene)benzohydrazide (H 2 L 2 ), and the acetohydroxamic acid (HL’) as ligands, have been synthesized and structurally characterized by physico-chemical methods and single crystal X-ray determination. Single crystal X-ray analysis indicates that the V atoms in the complexes are in octahedral coordination, with the ONO donor atoms of the hydrazone ligands, and the OO donor atoms of the acetohydroxamate ligands, as well as an oxido O atom. The complexes showed good property for the catalytic epoxidation of styrene.

Iridium complexes with ligands of 1,8-Naphthyridine-2-carboxylic acid derivatives-preparation and catalysis

Complexation of 1,8-naphthyridine(Np)-2-carboxylic derivatives L1-L3 [L1 = Np-2-COOH, L2 = Np-2-CONH2, L3 = Np-2-CONHCH2Py] with [Ir(COD)(µ-OMe)]2 yielded the corresponding complexes [Ir(COD)(Ln)] (1~3, n = 1~3, respectively). The potential tridentate L3 behaves as a bidentate donor in the complex 3. Treatment of L1 with [Ir(COD)Cl]2 under nitrogen atmosphere gave a Ir(III) hydride complex [Ir(COD)(L1)HCl] (4). However, carrying out the reaction in the presence of oxygen rendered a Ir(III) dichloride species [Ir(COD)(L1)Cl2] (5). All these complexes were characterized by spectroscopic analyses and X-ray single crystal determination. Catalytic activity of iridium complexes in amination of amines with alcohols was screened. It appears that iridium amido complexes 2 and 3 show excellent catalytic activity on amination of anilines with alcohols in the presence of Cs2CO3 at 120 °C.

Synthesis, crystal structures, and antimicrobial activities of copper(II) complexes with bis-Schiff bases

Three newly synthesized copper(II) complexes with the general formula [CuL], where L is the dianionic form of N,N′-bis(3,5-difluorosalicylidene)ethane-1,2-diamine (H2L1) for 1, N,N′-bis(3,5-difluorosalicylidene)propane-1,3-diamine (H2L2) for 2, and N,N′-bis(3,5-difluorosalicylidene)-2-hydroxy-1,3-propanediamine (H2L3) for 3, have been obtained and structurally characterized by spectroscopic method and single-crystal X-ray determination. The Cu atoms in the complexes are in square planar coordination, with the two imino N and two phenolate O atoms of the Schiff base ligands. The in vitro antimicrobial activities of the compounds indicate that they are interesting antibacterial agents.

Mechanism study on photo-oxidation dehydrogenation of cyclometalated Ir(III) amino acid complexes

Aerobic oxidation of amino acid complexes is an important process for the functionalization of amino acids. However, the reaction mechanism is still uncertain. Two enantiopure imino acid complexes Δ-[Ir(pq)2(ala-2H)] and Δ-[Ir(ppy)2(ala-2H)] (where pq is 2-phenylquinoline, ppy is 2-phenylpyridine and ala is alanine) have been synthesized respectively via the dehydrogenated oxidation reaction of the corresponding amino acid complexes Δ-[Ir(pq)2(l-ala)] and Δ-[Ir(ppy)2(l-ala)] in EtOH using visible light as the driving force and oxygen as an oxidant under mild conditions. The imino acid complexes have been fully characterized by NMR and MS techniques as well as X-ray single-crystal determination. The mechanism studies show singlet oxygen (1O2) is the main reactive oxygen species (ROS) and the carbon radical intermediate may involve in the reaction process. Therefore, a reaction mechanism involving the formation of a ligand-radical intermediate rather than the higher oxidation state of the metal center was proposed.

Two Zinc(II) Complexes with Similar Hydrazone Ligands: Syntheses, Crystal Structures and Antibacterial Activities

A pair of new mononuclear zinc(II) complexes with hydrazone ligands 4-methoxybenzoic acid (1-pyridin-2-ylmethylidene)hydrazide (HLa) and benzoic acid (1-pyridin-2-ylethylidene)hydrazide (HLb) were prepared. They are [Zn(La)2] (1) and [Zn(Lb)2] (2). The complexes were characterized by physico-chemical methods and single crystal X-ray determination. The tridentate hydrazone ligands coordinate to the Zn atoms through the pyridine nitrogen, imino nitrogen and enolate oxygen atoms. The Zn atom in each complex is six coordinated by two hydrazone ligands, to form octahedral coordination. The complexes have effective activities against the bacteria Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas fluorescens.

Vanadium complexes derived from fluoro-substituted Schiff bases: Synthesis, crystal structures, and antimicrobial activity

Two new vanadium complexes, [VO(L1)2] (1) and [V2O2(μ-O)2(L2)2] (2), where L1 is 2-(cyclohexyliminimethyl)-4,6-difluorophenolate, L2 is 2,4-difluoro-6-[(2-isopropylaminoethylimino)methyl]phenolate, have been synthesized and characterized by elemental analysis, FT-IR and UV-Vis spectra, and single crystal X-ray determination. The V atom in complex 1 is in a coordination between trigonal bipyramidal and square pyramidal, and that in complex 2 is in octahedral coordination. The antibacterial activity of the compounds against various bacteria was assayed. The fluoro-substituted groups play an essential role in the biological process.

Structural revision and pharmacological activity of hemslecin C

Hemslecin C, a compound with a novel skeleton, is synthesized by refluxing hemslecin A with KOH in alcohol. Hemslecin C was structurally characterized by specific optical rotation measurement, high-resolution mass spectroscopy, and nuclear magnetic resonance spectroscopic analysis. In addition, the molecular structure of hemslecin C was unambiguously determined by X-ray single-crystal determination. We found that its structure was different from that reported in the literature. The acetyl group of hemslecin A is transferred to the carbonyl α carbon of the side chain and is attacked by the 22-hydroxyl group to give a hemi-acetal that is dehydrated to give hemslecin C. The anticancer activity of this new skeleton is determined by sulforhodamine B assay method, and demonstrates excellent activity, thus providing a new framework for the development of anticancer drugs.

Synthesis, Characterization, X-Ray Crystal Structures and Antibacterial Activities of Oxidovanadium(V) Complexes with Hydrazone and Hydroxamate Ligands

Two new oxidovanadium(V) complexes, [VOL1L] (1) and [VOL2L]·CH3OH (2·CH3OH), where L1 and L2 are the dianionic form of N'-(3-bromo-2-hydroxybenzylidene)picolinohydrazide (H2L1) and 2-chloro-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H2L2), respectively, and L is the monoanionic form of 2-hydroxybenzohydroxamic acid (HL), were prepared and characterized by elemental analysis, infrared and electronic spectroscopy. Structures of the complexes were further confirmed by single crystal X-ray determination. The V atoms in the complexes are in octahedral coordination. The hydrazone ligands coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. The hydroxamate ligand coordinates to the V atom through the carbonyl and hydroxy O atoms. The complexes show effective antibacterial activity against B. subtilis, S. aureus and E. coli. The presence of Cl substitute group in the complex may enhance the antibacterial activity.

Syntheses, characterization, crystal structures, and antimicrobial activity of oxidovanadium(V) complexes with hydrazone and pyrone ligands

A pair of new oxidovanadium(V) complexes, [VOLL1] (1) and [VOLL2] (2), where L is the dianionic form of the hydrazone ligand N′-(2-hydroxy-3-methoxybenzylidene)-3-methylbenzohydrazide (H2L), L1 and L2 are the deprotonated form of 3-hydroxy-2-methyl-4H-pyran-4-one (HL1) and 3-hydroxy-2-ethyl-4H-pyran-4-one (HL2), respectively, have been prepared and characterized by elemental analyses, IR, UV-Vis, 1H NMR and single crystal X-ray determination. The V atoms in the complexes are in octahedral coordination, with the hydrazone ligand coordinates to the metal atoms through the phenolate O, imino N, and enolate O atoms, and with the pyrone ligands through the carbonyl and hydroxyl O atoms. The effect of the compounds on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.

Synthesis, characterization and single crystal X-ray structures of oxidovanadium(V) complexes derived from N’-(2-hydroxy-3-methoxybenzylidene)-3,5-dimethoxybenzohydrazide with antibacterial activity

A new oxidovanadium(V) complex, [VOL(OCH3)(CH3OH)] (1), was prepared from N’-(2-hydroxy-3-methoxybenzylidene)-3,5-dimethoxybenzohydrazide (H2L). Reaction of 1 with ethyl maltol (HL') in methanol afforded the new oxidovanadium(V) complex, [VOLL'] (2). The complexes were characterized by IR, UV and 1H NMR spectra. Structures of the complexes were further confirmed by single crystal X-ray determination. The V ions in the complexes are octahedral. The hydrazone ligands coordinate to V through the phenolate O, imino N, and enolate O. The ethyl maltolate ligand coordinates to V through the carbonyl and hydroxy oxygens. Both complexes show effective antibacterial activity against B. subtilis, S. aureus and P. aeruginosa. Thermogravimetric analysis was also performed.

Hydrogen Bonding Influenced Coordination Mode of Azide Ligand in Schiff base Copper(II) Complexes: Synthesis, Crystal Structures, and Antibacterial Activity

Two copper(II) complexes, [CuL1N3] (I) and [CuL2(μ1, 1-N3)] (II), where L1 = 2-[(2-diethylaminoethylimino)methyl]-4,6-difluorophenolate, L2 = 2,4-difluoro-6-[(2-isopropylaminoethylimino)-methyl]phenolate, have been prepared and structurally characterized by elemental analyses, IR and UV-Vis spectra, as well as single crystal X-ray determination (CIF files CCDC nos. 1848289 (I) and 1848290 (II)). In complex I, the Cu atom is in square planar coordination, with the azide ligand in terminal coordination mode. In complex II, the Cu atom is in square pyramidal coordination, with the azide ligand in end-on bridging mode. The crystals are stabilized by hydrogen bonds, which influence the coordination mode of the azide ligand. The complexes have strong antibacterial activity against B. subtilis and S. aureus.

Gross rearrangement of Fe(II) aggregate structure by replacement of two H+ by two Li+: Visualizing altered structure of acid versus conjugate base

Double deprotonation of [(H2L)FeCl2]2·FeCl2 with LiN(SiMe3)2 under varying conditions occurs to give the acid [(THF)2LiClFe2L2]2[Fe(OH)2], 1, and the lithium salt of its doubly deprotonated conjugate base Li2([(THF)1.5LiClFe2L2]2[Fe(O)2]), 2. Single crystal X-ray determination of both structures shows that replacement of two protons by two Li+ causes both oxo and chloride ligands to adopt higher connectivity bridging roles. This illustrates the core event of moving towards more closed and higher dimensionality. The added lithium ions bind to various nucleophilic centers in the resulting intimate ion pair, all with general contraction of the metal framework, as an illustration of the general shrinkage towards a compact solid as hydroxide is converted to oxide.

Vanadium(V) Complexes with Bromo-Substituted Hydrazones: Synthesis, Characterization, X-ray Crystal Structures and Antimicrobial Activity

Two new VV complexes with the bromo-substituted hydrazones N'-(3-bromo-2-hydroxybenzylidene)-3-hydroxy-4-methoxybenzohydrazide (H2L1), N'-(3-bromo-2-hydroxybenzylidene)-3,5-dimethoxybenzohydrazide (H2L2), [VOL1(OCH3)(CH3OH)] (1) and [VOL2(OCH3)(CH3OH)] (2), were synthesized and structurally characterized by IR, UV-Vis and 1H NMR spectroscopy, as well as single-crystal X-ray determination. The V atom in the mononuclear complexes are six-coordinated in octahedral geometry. The free hydrazones and the complexes were studied on their antibacterial activity on S. aureus, B. subtilis, E. coli and P. fluorescence, and antifungal activity on C. albicans and A. niger. The bromo groups of the hydrazone ligands may increase their antibacterial activity.

Synthesis, Crystal Structure and Antimicrobial Activity of a Linear Trinuclear Nickel(II) Complex with Schiff Base Ligand

A new linear trinuclear Schiff base nickel(II) complex, [NiNiL(α2-α1:α1-OAc)(OH2)2]·H2O, where L is the dianionic form of N,N'-bis(5-chloro-2-hydroxybenzylidene)-1,3-propanediamine (H2L), was synthesized and characterized by elemental analyses, IR spectroscopy, and X-ray single-crystal determination. There are three bridges across the Ni-Ni atom pairs, involving two phenolate O atoms of a Schiff base ligand, and an O-C-O moiety of a α2-α1:α1-OAc group. The Ni atoms have octahedral coordination. The acetate bridges linking the central and terminal nickel atoms are mutually trans. The adjacent NiαααNi distances are 3.047(1) α. The complex was evaluated for its antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and antifungal (Candida albicans and Aspergillus niger) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method.

Indole Diterpenoids from an Endophytic Penicillium sp.

A chemical investigation of the endophyte Penicillium sp. (strain ZO-R1-1), isolated from roots of the medicinal plant Zingiber officinale, yielded nine new indole diterpenoids (1-9), together with 13 known congeners (10-22). The structures of the new compounds were elucidated by 1D and 2D NMR analysis in combination with HRESIMS data. The absolute configuration of the new natural products 1, 3, and 7 was determined using the TDDFT-ECD approach and confirmed for 1 by single-crystal X-ray determination through anomalous dispersion. The isolated compounds were tested for cytotoxicity against L5178Y, A2780, J82, and HEK-293 cell lines. Compound 1 was the most active metabolite toward L5178Y cells, with an IC50 value of 3.6 μM, and an IC50 against A2780 cells of 8.7 μM. Interestingly, 1 features a new type of indole diterpenoid scaffold with a rare 6/5/6/6/6/6/5 heterocyclic system bearing an aromatic ring C, which is suggested to be important for the cytotoxic activity of this natural product against L5278Y and A2780 cells.

Synthesis, Characterization, and Crystal Structures of Oxidovanadium(V) Complexes Derived from 2-Chloro-N'-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide with Antimicrobial Activity

Two new oxodovanadium(V) complexes, [VO(L)(OEt)(MeOH)] (I) and [VO(L)(Bha)] · EtOH (II), where L is the anion of 2-chloro-N'-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide (H2L), Bha is the anion of 2-hydroxybenzohydroxamic acid (HBha), were prepared and characterized by IR, UV-Vis and single crystal X-ray determination (CIF files CCDC nos. 1840661 (I) and 1840662 (II)). Complex I crystallizes as the monoclinic space group P21/c with unit cell dimensions a = 8.272(1), b = 21.326(2), c = 12.979(1) A, β = 107.173(2)°, V = 2187.5(4) A3, Z = 4, R1 = 0.0811, wR2 = 0.2152, GOOF = 1.048. Complex II crystallizes as the triclinic space group P $$\bar {1}$$ with unit cell dimensions a = 7.407(2), b = 14.195(2), c = 14.330(2) A, α = 117.262(2)°, β = 92.947(2)°, γ = 95.771(2)°, V = 1324.4(4) A3, Z = 2, R1 = 0.0919, wR2 = 0.1539, GOOF = 0.986. X-ray analysis indicates that the complexes are mononuclear vanadium(V) species, with the V atoms in octahedral coordination. The complexes were evaluated for their antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescence) and antifungal (Candida albicans and Aspergillus niger) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. The two complexes have from medium to strong activities against B. subtilis, S. aureus, and E. coli.

Synthesis, characterization and crystal structures of copper(II), zinc(II) and vanadium(V) complexes, derived from 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide, with antibacterial activity

Three copper(II), zinc(II), and vanadium(V) complexes, [CuL(HL)]ClO4 (1), [ZnL2] (2) and [VO2L] (3), where L is the anionic form of 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL), were prepared and characterized by IR, UV–vis and single-crystal X-ray determination. X-ray analysis indicates that the complexes are mononuclear species, with the Cu and Zn ions in 1 and 2 in octahedral coordination, and with the V ion in 3 in trigonal bipyramidal coordination. The hydrazone compound and the three complexes were evaluated for antibacterial activities. The copper complex has effective activities.

Synthesis and Crystal Structure of a Polymeric Copper(II) Complex Derived from 2-Hydroxy-5-methylbenzaldehyde Oxime with Antibacterial Activities

A centrosymmetric O-bridged polynuclear copper(II) complex, [CuL2]n, where L is the deprotonated form of the Schiff base ligand 2-hydroxy-5-methylbenzaldehyde oxime, has been prepared and characterized by IR, UV and single-crystal X-ray determination. There is a crystallographic inversion center in the complex. The Cu atom in the complex is coordinated by the phenolate oxygen, imino nitrogen and hydroxyl oxygen atoms from two Schiff base ligands, forming octahedral geometry. The complex was tested in vitro for its antibacterial activity.

Syntheses, Crystal Structures, and Antibacterial Activity of Mononuclear Vanadium(V) Complexes with Aroylhydrazone and Pyrone as Mixed Ligands

Two mononuclear vanadium(V) complexes, [VOL1(KA)] (I) and [VOL2(EM)] (II), where L1 and L2 are the dianionic form of N'-(3-ethoxy-2-hydroxybenzylidene)-4-methoxybenzohydrazide (H2L1) and 4-bromo-N'-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide (H2L2), respectively; KA and EM are the monoanionic form of kojic acid and ethyl maltol, respectively, were prepared. The complexes were characterized by elemental analysis, IR and UV-Vis spectra, and single crystal X-ray determination (CIF files CCDC nos. 1823339 (I) and 1823341 (II)). The crystal of complex I crystallizes in the triclinic space group P–1 with unit cell a = 7.7813(16), b = 11.297(2), c = 14.3390(18) A, α = 90.449(2)°, β = 100.402(2)°, γ = 108.366(2)°, V = 1173.8(4) A3, Z = 2. The crystal of complex II crystallizes in the monoclinic space group P21/n with unit cell a = 8.6935(5), b = 30.9695(18), c = 18.4469(11) A, β = 99.366(2)°, V = 4900.3(5) A3, Z = 8. The V atoms in the complexes are in octahedral geometry. The antimicrobial activities of the compounds against K. pneumoniae, S. aureus, P. aeroginosa, E. coli, and B. subtilis were investigated.

Syntheses, characterization and crystal structures of Schiff base nickel(II) complexes with antibacterial activity

Two nickel(II) complexes, [NiL1N3] (1) and [Ni(HL2)2(NCS)2)] (2), where L1 = 2-[(2-diethylaminoethylimino)methyl]-4,6-difluorophenolate, L2 = 2,4-difluoro-6-[(2-isopropylaminoethylimino)methyl]phenolate, have been prepared and structurally characterized by elemental analyses, IR and UV-Vis spectra, as well as single crystal X-ray determination. In complex 1, the Ni atom is in square planar coordination, with three donor atoms of the deprotonated Schiff base ligand L1 and the azido N atom. In complex 2, the Ni atom is in octahedral coordination, with the three donor atoms of the zwitterionic Schiff base ligand HL2 and two thiocyanato N atoms. The crystals are stabilized by hydrogen bonds. The complexes have strong antibacterial activity against B. subtilis, S. aureus and E. coli.