56437-98-0Relevant academic research and scientific papers
Benzoylguanidines as Anion-Responsive Systems
Antol, Ivana,Bare?i?, Luka,Glasovac, Zoran,Margeti?, Davor
, p. 845 - 854 (2018/10/05)
A series of benzoylguanidinium salts was prepared and the changes in UV/Vis spectra, triggered by the presence of anions, were investigated. All compounds undergo deprotonation with basic anions like dihydrogenphosphate and acetate in acetonitrile. The most pronounced spectral changes were obtained by deprotonation of N1-benzoyl-N3-(p-nitrophenyl) guanidinium chloride which shows the naked-eye visible color change from colorless to yellow. Measured pKa(BH+) in acetonitrile ranges from 12–16, which is comparable to the pyridinium cations. The proton transfer equilibria were also tested in acetonitrile/water mixture where all but the most acidic derivatives showed pKa(BH+) of 4–6 units which corresponds to apparent association constants of 104–106 dm3 mol?1. UV/Vis spectra of neutral and protonated forms were modelled by the TD-DFT approach using CAM-B3LYP and PBE0 functionals and compared to CC2 results. In the case of CAM-B3LYP, a parameter ω, defining amount of long-range exchange correction, was varied to achieve the best agreement with the experimental spectra. The optimized ω parameters are 0.10 a0?1 for neutral benzoylguanidines and 0.20 a0?1 for neutral nitrobenzoyl and protonated systems. The larger ω parameter in the latter is ascribed to more pronounced charge transfer character of the HOMO-LUMO transition – the one responsible for the lowest energy absorption band.
Aroylthioureas: New organic ionophores for heavy-metal ion selective electrodes
Otazo-Sanchez, Elena,Perez-Marin, Leonel,Estevez-Hernandez, Osvaldo,Rojas-Lima, Susana,Alonso-Chamarro, Julian
, p. 2211 - 2218 (2007/10/03)
Thiourea derivatives (46 aroylthioureas) having different substituents close to the sulfur atom were synthesized and their ionophore potential in ion selective electrodes (ISEs) was examined. Structural considerations were taken into account based on the corresponding heavy-metal ISE parameters. As ionophores, some 1-furoyl-3-substitnted thioureas (series 2) gave the best results in Pb(II), Hg(II) and Cd(II) ISEs. The strong intramolecular hydrogen bond in series 2 allows ligand interaction only through the C=S group. Substituents on the furan and phenyl rings give rise to low solubility in the membrane plasticizer. 3-Alkyl substituted furoylthioureas improve solubility but enhance oxidative processes with chain length. New X-ray diffraction (XRD) structures and theoretical DFT calculations were considered in the analysis of the substituent influence on the selectivity of ISEs. These new ionophores have advantages because of their stability, simple synthesis and easy modification of the sulfur binding ability resulting from substitution.
THE METHANOLYSIS KINETICS AND DISSOCIATION CONSTANTS OF 1-(SUBST. BENZOYL)-3-PHENYLTHIOUREAS
Kavalek, Jaromir,Jirman, Josef,Machacek, Vladimir,Sterba, Vojeslav
, p. 593 - 600 (2007/10/02)
A series of seven 1-(subst. benzoyl)-phenylthioureas have been prepared and their dissociation constants and solvolysis rate constant have been measured in methanol at 25 deg C.The reaction constant found show that the solvolysis rate is limited by the attack of methoxide ion on the benzoyl carbonyl group of the non-dissociated substrate.The polar effect of substituents in benzoyl group is extensively transferred also by the intramolecular hydrogen bond.
INVESTIGATIONS IN THE SERIES OF ACYLTHIOUREAS. ACIDITY IN DIMETHYLFORMAMIDE
Masias, A.,Otazo, E.,Beletskaya, I. P.
, p. 591 - 594 (2007/10/02)
The pKa values of three series of substituted 1-furoyl- and 1-benzoyl-3-arylthioureas were determined in dimethylformamide.It was shown that the investigated acylthioureas are more acidic than pyridine-substituted thioureas and substituted thio
