93839-35-1Relevant academic research and scientific papers
A Comparison of the Selectivity of Extraction of [PtCl6]2- by Mono-, Bi-, and Tripodal Receptors That Address Its Outer Coordination Sphere
Warr, Rebecca J.,Bell, Katherine J.,Gadzhieva, Anastasia,Cabot, Rafel,Ellis, Ross J.,Chartres, Jy,Henderson, David K.,Lykourina, Eleni,Wilson, A. Matthew,Love, Jason B.,Tasker, Peter A.,Schr?der, Martin
, p. 6247 - 6260 (2016/07/06)
Extraction and binding studies of [PtCl6]2- are reported for 24 mono-, bi-, and tripodal extractants containing tris(2-Aminoethyl)amine (TREN) or tris(3-Aminopropyl)amine (TRPN) scaffolds. These reagents are designed to recognize the outer coordination sphere of [PtCl6]2- and to show selectivity over chloride anion under acidic conditions. Extraction from 0.6 M HCl involves protonation of the N-center in tertiary amines containing one, two, or three urea, amide, or sulfonamide hydrogen-bond donors to set up the following equilibrium: 2L(org) + 2H+ + [PtCl6]2- [(LH)2PtCl6](org). All reagents show higher Pt loading than trioctylamine, which was used as a positive control to represent commercial trialkylamine reagents. The loading of [PtCl6]2- depends on the number of pendant amides in the extractant and follows the order tripodal > bipodal > monopodal, with urea-containing extractants outperforming amide and sulfonamide analogues. A different series of reagents in which one, two, or three of the alkyl groups in tris-2-ethylhexylamine are replaced by 3-N′-hexylpropanamide groups all show a comparably high affinity for [PtCl6]2- and high selectivity over chloride anion in extractions from aqueous acidic solutions. 1H NMR titration of three extractants [LH·Cl] with [(Oct4N)2PtCl6] in CDCl3 provides evidence for high selectivity for [PtCl6]2- over chloride for tri-and bipodal extractants, which show higher binding constants than a monopodal analogue.
New 1H-Pyrazole-Containing Polyamine Receptors Able to Complex L-Glutamate in Water at Physiological pH Values
Miranda, Carlos,Escarti, Francisco,Lamarque, Laurent,Yunta, Maria J. R.,Navarro, Pilar,Garcia-Espana, Enrique,Jimeno, M. Luisa
, p. 823 - 833 (2007/10/03)
The interaction of the pyrazole-containing macrocyclic receptors 3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14(28),24-tetraene 1[L1], 13,26-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14(28),24-tetraene 2[L2], 3,9,12,13,16,22,25,26-octaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14(28),24-tetraene 3[L3], 6,19-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14,(28),24-tetraene 4[L4], 6,19-diphenethyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14(28),24-tetraene 5[L5], and 6,19-dioctyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1 11,14]-octacosa-1(27),11,14(28),24-tetraene 6[L6] with L-glutamate in aqueous solution has been studied by potentiometric techniques. The synthesis of receptors 3-6[L3-L6] is described for the first time. The potentiometric results show that 4[L4] containing benzyl groups in the central nitrogens of the polyamine side chains is the receptor displaying the larger interaction at pH 7.4 (Keff = 2.04 × 104). The presence of phenethyl 5[L5] or octyl groups 6[L6] instead of benzyl groups 4[L4] in the central nitrogens of the chains produces a drastic decrease in the stability [Keff = 3.51 × 102 (5), Keff = 3.64 × 102 (6)]. The studies show the relevance of the central polyaminic nitrogen in the interaction with glutamate. 1[L1] and 2[L2] with secondary nitrogens in this position present significantly larger interactions than 3[L3], which lacks an amino group in the center of the chains. The NMR and modeling studies suggest the important contribution of hydrogen bonding and π-cation interaction to adduct formation.
