Search results for "molecular structure"
showing 10 items of 1246 documents
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.
A new method of anomeric protection and activation based on the conversion of glycosyl azides into glycosyl fluorides
1993
Glycosyl azides provide reliable anomeric protection stable to conditions for hydrolytic removal of ester groups, for reductive opening or release of acetalic diol protection, for the introduction of ether-type protection, and for glycosylation processes. The utility of this anomeric protection is further enhanced as glycosyl azides may be converted into glycosyl fluorides, which can be activated for glycosylation reactions. To this end, glycosyl azides have been subjected to 1,3-dipolar cycloaddition with di-tert-butyl acetylenedicarboxylate. On treatment with hydrogen fluoride-pyridine complex the N-glycosyl triazole derivatives directly give glycosyl fluorides.
Folate-targeted supramolecular vesicular aggregates based on polyaspartyl-hydrazide copolymers for the selective delivery of antitumoral drugs.
2010
Supramolecular vesicular aggregates (SVAs) have the advantage of combining the safe and biocompatible properties of colloidal vesicular carriers based on phospholipids with those of polymeric materials, i.e. polyaspartyl-hydrazide (PAHy) copolymers. To provide SVAs with a certain tumour selectivity, folate moieties were chemically conjugated to PAHy copolymers. Physicochemical properties (mean sizes, polydispersity index and zeta potential) of folate-targeted SVAs (FT-SVAs) loaded with gemcitabine were evaluated. The antiproliferative and anticancer activity of gemcitabine-loaded FT-SVAs was evaluated against two cancer cell lines, i.e. MCF-7 cells which over-express the folate receptor and…
Synthesis and in vitro antimicrobial activities of new (cyano-NNO-azoxy) pyrazole derivatives
2011
The antibacterial and antifungal activity of a series of products, in which the 1,5-dimethyl-4-(cyano- NNO-azoxy)pyrazol-3-yl and 1,3-dimethyl-4-(cyano-NNO-azoxy)pyrazol-5-yl moieties were linked to pyridine, pyrazole, isoxazole, thiophene and the furan ring, were examined. No molecule displayed activity against the Gram-negative bacteria tested. Conversely, some compounds displayed activity against two Staphylococcus aureus strains, including the methicillin resistant strain. All compounds displayed interesting antifungal activity, the most active compound of the series being the thiophene derivative 7a. This compound’s activity against Candida krusei and Candida glabrata (MIC = 0.25 and 0…
Orthorhombic polymorphs of twotrans-4-aminoazoxybenzenes
2002
The two isomeric compounds 4-amino-ONN-azoxybenzene [or 1-(4-aminophenyl)-2-phenyldiazene 2-oxide], i.e. the alpha isomer, and 4-amino-NNO-azoxybenzene [or 2-(4-aminophenyl)-1-phenyldiazene 2-oxide], i.e. the beta isomer, both C(12)H(11)N(3)O, crystallized from a polar solvent in orthorhombic space groups, and their crystal and molecular structures have been determined using X-ray diffraction. There are no significant differences in the bond lengths and valence angles in the two isomers, in comparison with their monoclinic polymorphs. However, the conformations of the molecules are different due to rotation along the Ar-N bonds. In the alpha isomer, the benzene rings are twisted by 31.5 (2)…
Synthesis, structure, properties and antimicrobial activity of para trifluoromethyl phenylboronic derivatives
2021
The [2-formyl-4-(trifluoromethyl)phenyl]boronic acid as well as its benzoxaborole and bis(benzoxaborole) derivatives were obtained and their properties studied. The 2-formyl compound displays an unusual structure in the crystalline state, with a significant twist of the boronic group, whereas in DMSO solution it tautomerizes with formation of a cyclic isomer. All the studied compounds exhibit relatively high acidity as well as a reasonable antimicrobial activity. Docking studies showed interactions of all the investigated compounds with the binding pocket of Candida albicans LeuRS. High activity against Bacillus cereus was determined for the 2-formyl compound as well as for the novel bis(be…
Synthesis and biological evaluation of new bicyclic fluorinated uracils through ring-closing metathesis.
2006
Two families of bicyclic fluorinated uracils have been prepared starting from a gem-difluorinated unsaturated nitrile, by means of a ring-closing metathesis reaction to form the new ring, which is fused at the C-5/C-6 or N-1/C-6 positions of the uracil moiety. The selective formation of olefin regioisomers in the metathesis process can be controlled according to the reaction conditions (catalyst, solvent, and temperature). The acaricidal activities of the resulting compounds have also been investigated.
Cu2+and AMP complexation of enlarged tripodal polyamines
2006
The synthesis, characterization, Cu2+ coordination and interaction with AMP of three tripodal polyamines are reported. The polyamines are based on the structure of the tetraamine (tren) which has been enlarged with three propylamino functionalities (TAL), with a further anthrylmethyl fragment at one of its terminal primary nitrogens (ATAL) or with naphthylmethyl fragments at its three ends (N3TAL). The protonation constants of all three polyamines show that at pH 6, all six primary and secondary nitrogen atoms in the arms are protonated. The interaction with Cu2+ and AMP (adenosine-5′-monophosphate) has been studied by potentiometric, UV-Vis, ESI-MS spectroscopy and NMR techniques. pH-Metri…
Diorganotin(IV) N-acetyl-L-cysteinate complexes: synthesis, solid state, solution phase, DFT and biological investigations.
2009
Diorganotin(IV) complexes of N-acetyl-L-cysteine (H(2)NAC; (R)-2-acetamido-3-sulfanylpropanoic acid) have been synthesized and their solid and solution-phase structural configurations investigated by FTIR, Mössbauer, (1)H, (13)C and (119)Sn NMR spectroscopy. FTIR results suggested that in R(2)Sn(IV)NAC (R = Me, Bu, Ph) complexes NAC(2-) behaves as dianionic tridentate ligand coordinating the tin(IV) atom, through ester-type carboxylate, acetate carbonyl oxygen atom and the deprotonated thiolate group. From (119)Sn Mössbauer spectroscopy it could be inferred that the tin atom is pentacoordinated, with equatorial R(2)Sn(IV) trigonal bipyramidal configuration. In DMSO-d(6) solution, NMR spectr…
De novo design of protein kinase inhibitors by in silico identification of hinge region-binding fragments.
2013
Protein kinases constitute an attractive family of enzyme targets with high relevance to cell and disease biology. Small molecule inhibitors are powerful tools to dissect and elucidate the function of kinases in chemical biology research and to serve as potential starting points for drug discovery. However, the discovery and development of novel inhibitors remains challenging. Here, we describe a structure-based de novo design approach that generates novel, hinge-binding fragments that are synthetically feasible and can be elaborated to small molecule libraries. Starting from commercially available compounds, core fragments were extracted, filtered for pharmacophoric properties compatible w…