Copper-(II) and -(I) co-ordination by hexa-amine ligands of different rigidities. A thermodynamic, structural and electrochemical investigation †

Bazzicalupi, Carla; Bencini, Andrea; Ciattini, Samuele; Giorgi, Claudia; Masotti, Andrea; Paoletti, Piero; Valtancoli, Barbara; Navon, Nadav; Meyerstein, Dan

doi:10.1039/b002102o

Cited by 20 publications

(12 citation statements)

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“…The Cu II complex 12 is reduced directly to Cu 0 by a single two-electron process at -0.524 V. Such behavior may stem from the higher flexibility of the ligand, which does not allow the Cu I complex to be kinetically stable and enables the reduction of the Cu II center directly to Cu 0 . [22] The reaction of HgCl 2 with ligand 4 gave an insoluble white product, which was not soluble in any of the common solvents. However, when the reaction was performed with Hg(OCOCH 3 ) 2 , a white product 13 was obtained, which is soluble in MeCN and MeNO 2 , and decomposes in DMSO.…”

Section: Resultsmentioning

confidence: 99%

The Ligation Properties of some Reduced Schiff Base Selena/Telluraaza Macrocycles: Versatile Structural Trends

et al. 2005

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The chalcogenaaza macrocycles 4, 5 and 6 show versatility in ligation properties towards various transition metal ions. The structure of the reduced 22-membered selenaaza macrocycle 4 (C 32 H 36 N 4 Se 2 ) has been determined. The Ni II complex 7 exhibits coordination by the N4Se2 donor sites. The Pd II complexes 8, 9, 10, and 14 have been structurally characterized. The molecular structures of these complexes reveal interesting versatile ligating behaviors of the ligands. The Pd complexes 8, 9, and 14 display coordination by hard nitrogen donor atoms only, whereas the complex 10 showed coordina-

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Section: Resultsmentioning

confidence: 99%

The Ligation Properties of some Reduced Schiff Base Selena/Telluraaza Macrocycles: Versatile Structural Trends

et al. 2005

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“…Considering these derivatives as lead molecules we decided to investigate compounds which show some structural similarity with 1 - 5 as potential antiviral agents. Indeed, macrocyclic amines 6-9 investigated here, and reported earlier as metal complexing agents for supramolecular chemistry [ 24 , 25 , 26 , 27 ], contain a 15-membered macrocyclic ring based on o,o’-phenanthroline (in 6, 8 and 9 ) or a simplified 2,2’-bipyridyl scaffold (in 7 ), rather similar to the bicyclam ring present in 1, 2 and 3 . Furthermore, the secondary/tertiary amine functionalities thought to be important for the interaction of the drug with the CXCR4 antagonist [ 10 , 12 , 13 , 14 , 15 , 16 , 17 ] are also present in all the investigational compounds 6-8 used here.…”

Section: Resultsmentioning

confidence: 81%

“…Using AMD3100 (AnorMED, Langley, BC, Canada) as lead molecule, we investigated the structurally related macrocyclic polyamines 6-9 , reported earlier [ 24 , 25 , 26 , 27 ], in order to obtain compounds with lower toxicity or increased activity against both wild type isolates and viruses resistant to this class of drugs. Polyamines 6-9 are water soluble (as hydrobromides) making them interesting clinical candidates.…”

Section: Resultsmentioning

confidence: 99%

“…Polyamines 6-9 are water soluble (as hydrobromides) making them interesting clinical candidates. The phenanthroline-based polyamines 6 [ 24 ], 8 [ 27 ] and 9 [ 25 ] were synthesized by reaction of 2,9-bis(bromomethyl)-1,10-phenanthroline ( a ) [ 28 ] with 1,4,7-tritosyl-1,4,7-triaazaeptane ( b ) [ 29 ], tris[2-( N- tosylaminoethyl)]amine ( c ) [ 30 ] or 1-methyl-1,4-ditosyl-1,4-diazabutane [ 31 ] ( f ), respectively, in anhydrous CH 3 CN or DMF in the presence of Na 2 CO 3 or K 2 CO 3 as bases ( Scheme 1 ). The resulting tosylated derivatives d , e and h were then deprotected in HBr/CH 3 COOH affording compounds 6 , 8 and 9 , respectively, as the corresponding trihydrobromide ( 6 , 8 ) or tetrahydrobromide ( 9 ) salts.…”

Section: Resultsmentioning

confidence: 99%

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New Macrocyclic Amines Showing Activity as HIV Entry Inhibitors Against Wild Type and Multi-Drug Resistant Viruses

et al. 2009

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Considering as a lead molecule the chemokine CXCR4 receptor antagonist AMD-3100, which shows significant anti-HIV activity in vitro and in vivo, we investigated a series of structurally related macrocyclic polyamines incorporating o,o’-phenanthroline or 2,2’-bipyridyl scaffolds as potential antiviral agents with lower toxicity and increased activity against both wild type X4-tropic and dual tropic HIV strains. The antiviral activity of these compounds was evaluated by susceptibility assays in PBMC (Peripheral Blood Mononuclear Cells) and compared to that of AMD-3100. The newly investigated compounds showed IC50s values in the low micromolar range and significantly inhibited the viral replication of wild type X4-tropic isolate and dual tropic strains. These macrocyclic polyamines constitute a promising class of HIV entry inhibitors.

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“…Molecular Modeling Procedures : Molecular dynamics (MD) simulations were performed on L1 and L2 . The molecular solid state structure of closely related ligands was used to build up the starting geometries of both the ligands. MD simulations were carried out in vacuum as well as in implicit solvent, in the latter case a distance dependent dielectric constant set to 80r was used.…”

Section: Methodsmentioning

confidence: 99%

Switching on the Fluorescence Emission of Polypyridine Ligands by Simultaneous Zinc(II) Binding and Protonation

et al. 2020

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The synthesis and characterization of the two new open-chain ligands 1,15-bis-[6-(2,2'-bipyridyl)]-2,5,8,11,14-pentaaza-octadecane (L1) and 1,15-bis-[2-(1,10-phenanthroline)-9-methyl]-2,5,8,11,14-pentaazaoctadecane (L2), both featuring a tetraethylenpentaamine chain linking via methylene bridges the 6 and 2 positions of two identical 2,2'-bipyridyl (bpy) and 9-methyl-1,10phenanthroline (9-methyl-phen) moieties respectively, are reported. Their protonation and binding ability for Cu 2 + , Zn 2 + , Cd 2 + and Pb 2 + have been studied by coupling potentiometric titrations with UV-vis absorption and fluorescence emission measurements in water. L1 and L2 afford stable mono-and dinuclear complexes, in which the metal ion is bound by a single bpy or 9-methyl-phen unit and the amine groups on the aliphatic chain. However, L1 displays a greater binding ability for Cu 2 + and Zn 2 + with respect to L2, the stability constants of the [ML1] 2 + complexes being 21.8 (Cu 2 + ) and 19.4 (Zn 2 + ) log units vs 20.34 and 16.8 log. units for the corresponding L2 species. Among all the metal ions tested, only the Zn 2 + complex with L2 features an enhanced fluorescence emission at neutral pH, thanks to the simultaneous binding of one Zn 2 + ion and H + ion(s), that inhibits any possible photoinduced electron transfer (PET) process from the amine donors to the excited phen moiety. Binding of a second metal switches off the emission again.[a] Dr.by the structural characteristics of the ligand and its Zn 2 + complexes, including the number and disposition of amine donors, the overall rigidity of the molecular backbone, and, in the case of macrocyclic ligands, the dimension of the cavity. In these complexes, the heteroaromatic nitrogens are unequivocally coordinated to the metal cations. However, the stiffening of the macrocyclic structure imposed by the heteroaromatic moieties may not allow the simultaneous coordination to the metal cations of all the nitrogen donors of the binding unit. Interestingly enough, the 'benzylic' amine groups, close to the heteroaromatic unit, are not coordinated, or weakly coordinated, to the metal cation. Therefore, their lone pairs are able to quench the fluorophore excited state thanks to a photoinduced electron transfer (PET) process. As a consequence, normally fluorescent Zn 2 + complexes result to be scarcely emissive. [8a,b,22-24] In this paper, we extend this study to two open-chain ligands, L1 and L2 in Scheme 1, containing a pentaamine aliphatic chain linked at its extremities to two equal 2,2'bipyridyl (bpy) or 9-methyl-1,10-phenanthroline (9-methylphen) moieties, respectively. Our purpose is the analysis of the effects on both metal binding and sensing of the presence of two fluorogenic units linked by a flexible chain.Therefore, complex stability and fluorescence emission in the presence of metal cations will be compared to those of the previously reported ligands L3 [24] and L4 [8a] (Scheme 1), which contain the same aliphatic pentaamine chain linking the 6,6' and 2,9 positions of a single...

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Copper-(II) and -(I) co-ordination by hexa-amine ligands of different rigidities. A thermodynamic, structural and electrochemical investigation †

Cited by 20 publications

References 50 publications

The Ligation Properties of some Reduced Schiff Base Selena/Telluraaza Macrocycles: Versatile Structural Trends

The Ligation Properties of some Reduced Schiff Base Selena/Telluraaza Macrocycles: Versatile Structural Trends

New Macrocyclic Amines Showing Activity as HIV Entry Inhibitors Against Wild Type and Multi-Drug Resistant Viruses

Switching on the Fluorescence Emission of Polypyridine Ligands by Simultaneous Zinc(II) Binding and Protonation

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