229 research outputs found
Tales of the unexpected: The case of zirconium(IV) complexes with desferrioxamine
The Zr4+ complexes with desferrioxamine (H3DFO) and its derivatives are the only 89Zr-based imaging agents for proton emission tomography (PET) that have been used so far in clinical trials. Nevertheless, a complete speciation of the Zr4+/H3DFO system in solution has never been performed and the stability constants of the relevant complexes are still unknown. Here we report, for the first time, the speciation of this system in water, performed by potentiometric titrations, and the determination of the stability constants of all complexes formed in the pH range 2.5–11.5. Surprisingly, although desferrioxamine gives rise to very stable 1:1 complexes with Zr4+ (logK = 36.14 for Zr4+ + DFO3− = [ZrDFO]+), 2:2 and 2:3 ones are also formed in solution. Depending on the conditions, these binuclear complexes can be main species in solution. These results were corroborated by small-angle X-ray scattering (SAXS) and MALDI mass spectrometry analyses of complex solutions. Information on complex structures was obtained by means of density functional theory (DFT) calculations
Solution Studies and Crystal Structures of Heteropolynuclear Potassium/Copper Complexes with Phytate and Aromatic Polyamines: Self-Assembly through Coordinative and Supramolecular Interactions
Sensing Zn2+ in aqueous solution with a fluorescent scorpiand macrocyclic ligand decorated with an anthracene bearing tail
Synthesis of the new scorpiand ligand L composed of a [9]aneN3 macrocyclic ring bearing a CH2CH2NHCH2-anthracene tail is reported. L forms both cation (Zn2+) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 Âą 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn2+ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn2+ in the pH range 6â10 down to nM concentrations of the metal ion. L can efficiently sense Zn2+ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion
Colorimetric response to anions by a "robust" copper(II) complex of a [9]aneN3 pendant arm derivative: CN- and I- selective sensing
The 1 : 1 complex [Cu(L)](BF4)2MeCN (1) of the tetradentate ligand 1-(2-quinolinylmethyl)-1,4,7-triazacyclononane (L) selectively changes its colour in the presence of CN in H2O and MeCN (without undergoing decomplexation from the macrocyclic ligand). The same complex in MeCN assumes different colours in the presence of CN or I
DNA binding by a new metallointercalator that contains a proflavine group bearing a hanging chelating unit.
Induction of a four-way junction structure in the DNA palindromic hexanucleotide 5 '-d(CGTACG)-3 ' by a mononuclear platinum complex
Four-way junctions (4WJs) are supramolecular DNA assemblies comprising four interacting DNA strands that in biology are involved in DNA-damage repair. In this study, a new mononuclear platinum(II) complex 1 was prepared that is capable of driving the crystallization of the DNA oligomer 5 '-d(CGTACG)-3 ' specifically into a 4WJ-like motif. In the crystal structure of the 1-CGTACG adduct, the distorted-square-planar platinum complex binds to the core of the 4WJ-like motif through pi-pi stacking and hydrogen bonding, without forming any platinum-nitrogen coordination bonds. Our observations suggest that the specific molecular properties of the metal complex are crucially responsible for triggering the selective assembly of this peculiar DNA superstructure.Metals in Catalysis, Biomimetics & Inorganic Material
Induction of a FourâWay Junction Structure in the DNA Palindromic Hexanucleotide 5â˛âd(CGTACG)â3Ⲡby a Mononuclear Platinum Complex
Fourâway junctions (4WJs) are supramolecular DNA assemblies comprising four interacting DNA strands that in biology are involved in DNAâdamage repair. In this study, a new mononuclear platinum(II) complex 1 was prepared that is capable of driving the crystallization of the DNA oligomer 5â˛âd(CGTACG)â3Ⲡspecifically into a 4WJâlike motif. In the crystal structure of the 1âCGTACG adduct, the distortedâsquareâplanar platinum complex binds to the core of the 4WJâlike motif through ĎâĎ stacking and hydrogen bonding, without forming any platinumânitrogen coordination bonds. Our observations suggest that the specific molecular properties of the metal complex are crucially responsible for triggering the selective assembly of this peculiar DNA superstructure.Metals in Catalysis, Biomimetics & Inorganic Material
- âŚ