Highly Stable Self-Association of 5-(Guanidiniocarbonyl)-1H-pyrrole-2-carboxylate in DMSO – The Importance of Electrostatic Interactions
作者:Carsten Schmuck
DOI:10.1002/(sici)1099-0690(199909)1999:9<2397::aid-ejoc2397>3.0.co;2-3
日期:1999.9
led to binding constants of K ≈ 106 mol–1 in DMSO and K ≈ 103 mol–1 in 40% water/DMSO for carboxylate binding by the 2-(guanidiniocarbonyl)pyrrole moiety. The stability constant for the dimer 12 in DMSO could therefore be estimated as K ≈ 1012 mol–1. In solution, the self-association process of 1 can be completely disrupted by protonation of the carboxylate group. In the solid state, however, the hydrochloride
两性离子化合物5-(胍基碘羰基)-1 H-吡咯-2-羧酸酯(1)自组装形成二聚体,即使在170°C或0.001 mM的浓度下,它们在DMSO中也完全稳定。这种高稳定性源于多种弱相互作用的结合。用(1 H-吡咯-2-羰基)胍(6)和[5-(甲氧基羰基)-1 H-吡咯-2-羰基]胍(8)的1 H-吡咯-2-羧酸酯(5)的NMR滴定。导致结合常数ķ ≈10 6摩尔-1在DMSO和ķ ≈10 3摩尔-1在40%的水/ DMSO中溶解2-(胍基碘羰基)吡咯部分的羧酸盐。对于二聚体的稳定性常数1 2因此在DMSO可估计为ķ ≈10 12摩尔-1。在溶液中,羧基的质子化可完全破坏1的自缔合过程。然而,在固态下,盐酸盐1 +也以相似但仅极弱地与氢键结合的二聚体形式存在。