Synthesis of three dissymmetrical pentaamines via bisaminals of linear tetraamines

Bisaminals of linear tetraamines were selectively N-monofunctionalised with acrylonitrile in a Michael-type addition giving rise, after reduction, to three open-chain dissymmetrical pentaamines, bearing a new aminopropyl group on one terminal nitrogen atom.

A new bis-tetraamine ligand with a chromophoric 4-(9-anthracenyl)-2,6-dimethylpyridinyl linker for glyphosate and ATP sensing

The synthesis of a new linear bis-tetraamine ligand L1, based on two 1,4,8,11-tetraazaundecane units grafted at the 2 and 6 positions of a pyridinyl linker substituted by an anthracenyl fluorophore in the para position, is described and anion complexation studies of L1 with anionic substrates are reported. The protonation pattern and the study of the binding properties of L1 in an aqueous medium with two anionic substrates, the nucleotide adenosine triphosphate (ATP) and the herbicide glyphosate (N-(phosphonomethyl)glycine, PMG), were investigated by means of potentiometry, NMR spectroscopy and absorption and emission spectroscopic techniques. To decipher the impact of the chromophoric linker on the complexation process and to highlight its optical properties, a comparison is established with its previously reported analog L2 devoid of the anthracenyl group. The results unambiguously show that the protonation and complexation properties are preserved despite the presence of the bulky linker, allowing for the use of L1 as a fluorescent sensor for ATP and PMG.

Exploring new molecular architectures for anion recognition: synthesis and ATP binding properties of new cyclam-based ditopic polyammonium receptors

Synthesis and characterization of three new polyamine receptors, composed of a cyclam unit (cyclam=1,4,8,11-tetraazacyclotetradecane) linked by a 2,6-dimethylpyridinyl spacer to the linear polyamines 1,4,8,11-tetraazaundecane (L1py), 1,4,7-triazaheptane (L2py), and to a quaternary ammonium group (L3py(+)), are reported. All receptors form highly charged polyammonium cations at neutral pH, suitable for anion recognition studies. ATP recognition was analyzed by using potentiometric, calorimetric, (1)H and (31)P NMR measurements in aqueous solution. All receptors form 1:1 adducts with ATP in aqueous solution, stabilized by charge-charge and hydrogen-bonding interactions between their ammonium groups and the anionic triphosphate chain of ATP. The binding ability of the three receptors for ATP increases in the order of L3py(+)<L2py<L1py. These adducts are stabilized by largely favourable entropic contributions, probably due to the large desolvation of the host and guest species upon complexation. The sequence observed for the binding affinity is explained in terms of the different ability of the three receptors to wrap around the phosphate chain of ATP.