14 research outputs found
Di-maltol-polyamine ligands to form heterotrinuclear metal complexes: solid state, aqueous solution and magnetic characterization
The binding properties of the two ligands (L) N,Nâ-bis[(3-hydroxy-4-pyron-2-yl)methyl]-N,Nâ-dimethylethylendiamine
(Malten) and 4,10-bis[(3-hydroxy-4-pyron-2-yl)methyl]-1,7-dimethyl-1,4,7,10-tetraazacyclododecane
(Maltonis) towards M(II) transition metal ions (M(II) = Cu(II) for Malten and Co(II) for
Maltonis, respectively), were investigated in aqueous solution. Each compound contains two 3-hydroxy-
2-methyl-4-pyrone units (Maltol) symmetrically spaced by a different polyamine fragment. The formation
of only mononuclear complexes was detected and the main species present in a wide range of pH is the
neutral [M(II)(Hâ2L)] complex. This is able to stabilize one hard M(III) metal ion such as Gd(III) and Y(III),
giving rise to the formation of new hetero-trinuclear complexes of M(II)âM(III)âM(II) sequence. The trinuclear
species having the formula {M(III)[M(II)(Hâ2L)]2}3+ (M(II) = Cu(II) and M(III) = Y(III) or Gd(III) for Malten
and M(II) = Co(II) and M(III) = Gd(III) for Maltonis) are also formed in a wide range of pH, including pH = 7
and can be isolated in high yield as a perchlorate salt. The crystal structures of all the studied heterotrinuclear
species highlight that such systems are formed thanks to the synergy between the different
stereochemical requirement of the transition metal (Cu(II) or Co(II)) and the different donor atoms set of
the ligands which preorganize the maltol units for the binding of the hard M(III) metal, otherwise
difficult to bind in water, through L/M(II)/M(III) self-assembling. The magnetic properties of the heterotrinuclear
spin systems were investigated; in the M(II)âGd(III)âM(II) species, Gd(III) interacts with the two 3d
ions of this class of compounds by similar coupling mechanism
PluS Nanoparticles as a tool to control the metal complex stoichiometry of a new thio-aza macrocyclic chemosensor for Ag(I) and Hg(II) in water
We report here the synthesis of a new thio-âaza macrocyclic chemosensor based on the 2,â5-âdiphenyl[1,â3,â4]âoxadiazole in which two thioether groups were inserted in a macrocycle with the aim to make it suitable for the coordination of soft and heavy metal ions. In acetonitrile soln., the fluorescence of the chemosensor changes upon addn. of different metal ions, such as Cu(II)â, Zn(II)â, Cd(II)â, Pb(II)â, Hg(II) and Ag(I)â, that form a not fluorescent ML species and a fluorescent M2L species characterized also via NMR expts. The hosting of the chemosensor inside the PluS Nanoparticles leads to a high water soly., allowing to perform the metal detection without the use of addnl. solvents and also induced an higher selectivity towards Ag(I) and Hg(II)â. Moreover, it was demonstrated for the first time the possibility to control the stoichiometry of the formed complex upon changing the no. of ligands per nanoparticles. To our opinion, this possibility can give an addnl. tool for the tuning of the affinity and selectivity of the chemosensor that could be of great interest for the design of more and more efficient systems
Modulating the Sensor Response to Halide Using NBD-Based Azamacrocycles
Ligand L (2,6-bis{[7-(7-nitrobenzo[1,2,5]oxadiazole-4-yl)-3,10-dimethyl-1,4,7,10-tetraazacyclododeca-1-yl]methyl}phenol) is a fluorescent sensor that is useful for detecting Cu(II), Zn(II), and Cd(II). Some of the complexes formed are able to sense the presence of halides in solution. L passes through the cellular membrane, becoming fluorescent inside cells. The Hâ1Lâ species is able to form dinuclear complexes with [M2Hâ1L]3+ stoichiometry with Cu(II), Zn(II), and Cd(II) ions, experiencing a CHEF effect upon metal coordination in an acetonitrile/water 95:5 (v/v) solution. In all three of the complexes investigated, the metal cations are coordinatively unsaturated and can therefore bind secondary ligands as anionic species. The crystal structure of [Cd2(Hâ1L)Cl2](ClO4)â˘4H2O is discussed. The Zn(II) complex behaves as an OFFâON sensor for fluoride and chloride anions
Modulating the Sensor Response to Halide Using NBD-Based Azamacrocycles
Ligand <b>L</b> (2,6-bisÂ{[7-(7-nitrobenzoÂ[1,2,5]Âoxadiazole-4-yl)-3,10-dimethyl-1,4,7,10-tetraazacyclododeca-1-yl]Âmethyl}Âphenol)
is a fluorescent sensor that is useful for detecting CuÂ(II), ZnÂ(II),
and CdÂ(II). Some of the complexes formed are able to sense the presence
of halides in solution. <b>L</b> passes through the cellular
membrane, becoming fluorescent inside cells. The H<sub><i>â</i>1</sub><b>L</b><sup><i>â</i></sup> species
is able to form dinuclear complexes with [M<sub>2</sub>H<sub><i>â</i>1</sub><b>L</b>]<sup>3+</sup> stoichiometry
with CuÂ(II), ZnÂ(II), and CdÂ(II) ions, experiencing a CHEF effect upon
metal coordination in an acetonitrile/water 95:5 (v/v) solution. In
all three of the complexes investigated, the metal cations are coordinatively
unsaturated and can therefore bind secondary ligands as anionic species.
The crystal structure of [Cd<sub>2</sub>(H<sub><i>â</i>1</sub><b>L</b>)ÂCl<sub>2</sub>]Â(ClO<sub>4</sub>)¡4H<sub>2</sub>O is discussed. The ZnÂ(II) complex behaves as an OFFâON
sensor for fluoride and chloride anions
Modulating the Sensor Response to Halide Using NBD-Based Azamacrocycles
Ligand <b>L</b> (2,6-bisÂ{[7-(7-nitrobenzoÂ[1,2,5]Âoxadiazole-4-yl)-3,10-dimethyl-1,4,7,10-tetraazacyclododeca-1-yl]Âmethyl}Âphenol)
is a fluorescent sensor that is useful for detecting CuÂ(II), ZnÂ(II),
and CdÂ(II). Some of the complexes formed are able to sense the presence
of halides in solution. <b>L</b> passes through the cellular
membrane, becoming fluorescent inside cells. The H<sub><i>â</i>1</sub><b>L</b><sup><i>â</i></sup> species
is able to form dinuclear complexes with [M<sub>2</sub>H<sub><i>â</i>1</sub><b>L</b>]<sup>3+</sup> stoichiometry
with CuÂ(II), ZnÂ(II), and CdÂ(II) ions, experiencing a CHEF effect upon
metal coordination in an acetonitrile/water 95:5 (v/v) solution. In
all three of the complexes investigated, the metal cations are coordinatively
unsaturated and can therefore bind secondary ligands as anionic species.
The crystal structure of [Cd<sub>2</sub>(H<sub><i>â</i>1</sub><b>L</b>)ÂCl<sub>2</sub>]Â(ClO<sub>4</sub>)¡4H<sub>2</sub>O is discussed. The ZnÂ(II) complex behaves as an OFFâON
sensor for fluoride and chloride anions