Search results for "ligand"
showing 10 items of 2559 documents
Mononuclear and tetranuclear Fe(III) complexes with two different types of N, O donor Schiff base ligands
2013
Abstract A mononuclear Fe(III) complex of a tetradentate N 2 O 2 donor Schiff base ligand derived from 3-ethoxysalicaldehyde and ethylenediamine has been reported. In addition two tetranuclear Fe(III) complexes with discrete Fe 4 III (μ 4 -O) cores have been synthesized and characterized using two Schiff base ligands (H 2 L 1–2 ) derived from two different aromatic acid hydrazides and diacetyl monoxime. The mononuclear Fe(III) and one of the tetranuclear Fe(III) complexes have been structurally characterized by single-crystal X-ray crystallography. The mononuclear complex has a highly distorted octahedral geometry. The tetranuclear Fe(III) complexes are found to be rare examples with discre…
Ligand Design for Heterobimetallic Single-Chain Magnets: Synthesis, Crystal Structures, and Magnetic Properties of MIICuII (M=Mn, Co) Chains with Ste…
2006
Two new series of neutral ox-amato-bridged heterobimetallic chains of general formula [MCu(L x ) 2 ]- m DMSO (m=0-4) (L 1 =N-2-methyl-phenyloxamate, M=Mn (1a) and Co (1 b); L2 = N-2,6-dimethylphenyloxamate, M=Mn (2a) and Co (2b); L 3 = N-2,4,6-trimethylphenyloxamate, M= Mn (3a) and Co (3b)) have been prepared by reaction between the corresponding anionic oxamatocopper(II) complexes [Cu(L x ) 2 ] 2- with Mn 2+ or Co 2+ cations in DMSO. The crystal structures of [CoCu(L 2 ) 2 (H 2 O) 2 ] (2b') and [CoCu(L 3 ) 2 (H 2 O) 2 ]·4H 2 O (3b') have been solved by single-crystal X-ray diffraction methods. Compounds 2b' and 3b' adopt zigzag and linear chain structures, respectively. The intrachain Cu··…
Highly Robust but Surface-Active : An N-Heterocyclic Carbene-Stabilized Au25 Nanocluster
2019
Surface organic ligands play a critical role in stabilizing atomically precise metal nanoclusters in solutions. However, it is still challenging to prepare highly robust ligated metal nanoclusters that are surface-active for liquid-phase catalysis without any pre-treatment. Now, an N-heterocyclic carbene-stabilized Au25 nanocluster with high thermal and air stabilities is presented as a homogenous catalyst for cycloisomerization of alkynyl amines to indoles. The nanocluster, characterized as [Au25(iPr2-bimy)10Br7]2+ (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene) (1), was synthesized by direct reduction of AuSMe2Cl and iPr2-bimyAuBr with NaBH4 in one pot. X-ray crystallization analysis …
Involvement of PAR-4 in Cannabinoid-Dependent Sensitization of Osteosarcoma Cells to TRAIL-Induced Apoptosis
2014
The synthetic cannabinoid WIN 55,212-2 is a potent cannabinoid receptor agonist with anticancer potential. Experiments were performed to determine the effects of WIN on proliferation, cell cycle distribution, and programmed cell death in human osteosarcoma MG63 and Saos-2 cells. Results show that WIN induced G2/M cell cycle arrest, which was associated with the induction of the main markers of ER stress (GRP78, CHOP and TRB3). In treated cells we also observed the conversion of the cytosolic form of the autophagosome marker LC3-I into LC3-II (the lipidated form located on the autophagosome membrane) and the enhanced incorporation of monodansylcadaverine and acridine orange, two markers of t…
Spacer-separated sialyl LewisX cyclopeptide conjugates as potential E-selectin ligands.
2006
Completely protected sialyl LewisX azide was synthesized from a neolactosamine azide precursor carrying a 3-O-allyloxycarbonyl group as the temporary protecting group. After its Pd(0)-catalyzed deprotection and stereoselective alpha-fucosylation, the obtained LewisX azide was subjected to O-deacetylation in the galactose unit and subsequent regio- and stereoselective sialylation. Reduction of the anomeric azido group afforded the sialyl LewisX amine building block. Two molecules of this tetrasaccharide ligand were conjugated to a preformed cyclooctapeptide containing two equidistant l-asparagine units equipped with carboxy-terminated tetraethyleneglycol side chains to give, after deprotecti…
Stepwise formation of a pentanuclear Ni4Cu heterometallic complex exhibiting a vertex-sharing defective double-cubane core and diphenoxo- and phenoxo…
2013
Sequential reaction of a N5O3 octadentate tripodal ligand with Ni(2+) and subsequently with Cu(2+) and azide ligand afforded the first example of a heterobridged (phenoxo/μ(1,1)-azido) pentanuclear heterometallic (Ni4Cu) compound, which exhibits a centrosymmetric vertex-sharing defective double-cubane structure. The study of the magnetic properties reveals that the compound shows ferromagnetic interaction interactions, leading to an S = 9/2 spin ground state. Density functional theory calculations on the X-ray structure and model compounds predict ferromagnetic interactions through the magnetic exchange pathways involving each couple of metal ions.
The azido ligand: a useful tool in designing chain compounds exhibiting alternating ferro- and antiferro-magnetic interactions
1997
A one-pot reaction of NiII 1, CoII 2, FeII 3 and MnII 4 with 2,2A-bipyridine (bipy) and azide in water leads to [M(bipy)(N3)2]n chains where the metal ion is alternatively bridged by double end-on (EO) and end-to-end (EE) azido bridges; theoretical analysis of the variable-temperature magnetic susceptibility data of 1 and 4 reveals the occurrence of intrachain alternating ferro- (through EO) and antiferro-magnetic (through EE) interactions. Julve Olcina, Miguel, Miguel.Julve@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Clemente Juan, Juan Modesto, Juan.M.Clemente@uv.es
Synthesis and structural studies by infrared and Mössbauer spectroscopy of adducts of tin(IV) and organotin(IV) derivatives with 2,2′-azopyridine
1985
Abstract A number of complexes have been prepared by the reaction between 2,2′-azopyridine(AZP) and tin(IV) halides and organotin(IV) halides, and characterized by elemental analysis and infrared and variable temperature 119Sn Mossbauer spectroscopies. All of the new compounds have 1:1 stoichiometry, with the AZP ligand occupying two coordination sites by bonding through one of the ring and one of the azo group nitrogen atoms, to give rise to distorted octahedral structures. In the diorganotin complexes the two organic groups occupy trans positions. The infrared and Mossbauer spectroscopic data suggest that these compounds are monomeric in the solid state.
Enzymatic Synthesis of 3′–5′, 3′–5′ Cyclic Dinucleotides, Their Binding Properties to the Stimulator of Interferon Genes Adaptor Protein, and Structu…
2021
The 3′–5′, 3′–5′ cyclic dinucleotides (3′3′CDNs) are bacterial second messengers that can also bind to the stimulator of interferon genes (STING) adaptor protein in vertebrates and activate the host innate immunity. Here, we profiled the substrate specificity of four bacterial dinucleotide synthases from Vibrio cholerae (DncV), Bacillus thuringiensis (btDisA), Escherichia coli (dgcZ), and Thermotoga maritima (tDGC) using a library of 33 nucleoside-5′-triphosphate analogues and then employed these enzymes to synthesize 24 3′3′CDNs. The STING affinity of CDNs was evaluated in cell-based and biochemical assays, and their ability to induce cytokines was determined by employing human peripheral …
Lowest triplet excited states of a novel heteroleptic iridium(III) complex and their role in the emission colour
2009
Abstract The [Ir(ppy-F 2 ) 2 Me 4 phen] +1 complex, where ppy-F 2 is 2-(2′,4′-fluorophenyl)pyridine and Me 4 phen is 3,4,7,8-tetramethyl-1,10-phenanthroline, has been theoretically investigated by means of DFT calculations. The molecular and electronic properties calculated for [Ir(ppy-F 2 ) 2 Me 4 phen] +1 are compared with those obtained for the simpler [Ir(ppy)(bpy)] +1 complex. The introduction of fluorine substituents in the ppy ligands and the use of phenanthroline instead of 2,2′-bipyridine as the diimine ligand increase the HOMO–LUMO energy gap and blue-shift the emission colour. The phenanthroline ligand causes the appearance of two nearly-degenerate LUMO orbitals of different symm…