Bis-maltol-polyamine family: structural modifications at strategic positions. Synthesis, coordination and antineoplastic activity of two new ligands

Substitution at the maltol C6 position affects the antineoplastic and coordination properties of Malten, acting on degradation time, binding ability and biological activity.

Playing with Structural Parameters: Synthesis and Characterization of Two New Maltol-Based Ligands with Binding and Antineoplastic Properties

Two maltol-based ligands, N,N′-bis((3-hydroxy-4-pyron-2-yl)methyl)-1,4-piperazine (L1) and N,N′,N′-tris((3-hydroxy-4-pyron-2-yl)methyl)-N-methylethylendiamine (L2), were synthesized and characterized. L1 and L2, containing, respectively, two and three maltol units spaced by a diamine fragment, were designed to evaluate how biological and binding features are affected by structural modifications of the parent compound malten. The acid-base behavior and the binding properties towards transition, alkaline-earth (AE) and rare-earth (RE) cations in aqueous solution, studied by potentiometric, UV-Vis and NMR analysis, are reported along with biological studies on DNA and leukemia cells. Both ligands form stable complexes with Cu(II), Zn(II) and Co(II) that were studied as metallo-receptors for AE and RE at neutral pH. L1 complexes are more affected than L2 ones by hard cations, the L1-Cu(II) system being deeply affected by RE. The structural modifications altered the mechanism of action: L1 partially maintains the ability to induce structural alterations of DNA, while L2 provokes single strand (nicks) and to a lesser extent double strand breaks of DNA.

Radical polymerization as a versatile tool for surface grafting of thin hydrogel films

The surface of solid substrates is the main part that interacts with the environment.

Insights into the Chemical Mechanism for CO2(aq) and H+ in Aqueous Diamine Solutions - An Experimental Stopped-Flow Kinetic and 1H/13C NMR Study of Aqueous Solutions of N,N-Dimethylethylenediamine for Postcombustion CO2 Capture

In an effort to advance the understanding of multiamine based CO₂ capture process absorbents, we report here the determination of the kinetic and equilibrium constants for a simple linear diamine N,N-dimethylethylenediamine (DMEDA) via stopped-flow spectrophotometric kinetic measurements and ¹H/¹³C NMR titrations at 25.0 °C. From the kinetic data, the formation of monocarbamic acid (DMEDACOOH) from the reaction of DMEDA with CO₂(aq) is the dominant reaction at high pH > 9.0 (k₇ = 6.99 × 10³ M^-1·s^-1). Below this pH, the formation of protonated monocarbamic acid (DMEDACOOH₂) via the pathway involving DMEDAH⁺ and CO₂(aq) becomes active and contributes to the kinetics despite the 107-fold decrease in the rate constant between the two pathways. ¹H and ¹³C NMR spectra as a function of decreasing pH (increasing HCl concentration) at 25.0 °C have been evaluated here to confirm the protonation events in DMEDA. Calculations of the respective DMEDA nitrogen partial charges have also been undertaken to support the NMR protonation study. A comparison of the DMEDA kinetic constants with the corresponding data for piperazine (PZ) reveals that despite the larger basicity of DMEDA, the enhanced and superior kinetic performance of PZ with CO₂(aq) above its predicted Bronsted reactivity is not observed in DMEDA.