The interactions between zinc salts and the naturally occurring cyclic octapeptide ascidiacyclamide in methanol, as well as a synthetic analogue cyclo[Ile(Oxn)-D-Val(Thz)]2, were monitored by 1H NMR and CD spectroscopy. Three zinc complexes were identified, their relative amounts depending on the nature of the anion (perchlorate, triflate or chloride) and the presence or absence of base. Binding constants for two of the zinc species were calculated from CD or 1H NMR spectra, [Zn(L – H)]+ (KZn(L–H) = [Zn(L – H)+]/[Zn2+][(L – H)–] = 107 ± 2 M–1; 95% methanol/5% water, 298.0 K, NEt3/HClO4 buffer 0.04 M) and [ZnLCl]+ (KZnClL = [ZnClL+]/[Zn2+][Cl–][L] = 107.2 ± 0.1 M–2; d3-methanol, 301 K).
通过 1H NMR 和 CD 光谱监测了
锌盐与
甲醇中天然存在的环状八肽 ascidiacyclamide 以及合成类似物 cyclo[Ile(Oxn)-D-Val(Thz)]2 之间的相互作用。确定了三种
锌络合物,其相对含量取决于阴离子的性质(
高氯酸盐、三酸盐或
氯化物)以及碱的存在与否。根据 CD 或 1H NMR 光谱计算出其中两种
锌的结合常数:[Zn(L - H)]+ (KZn(L-H) = [Zn(L - H)+]/[Zn2+][(L - H)-] = 107 ± 2 M-1; 95%
甲醇/5%
水,298.0 K,NEt3/HClO4 缓冲液 0.04 M)和 [ZnLCl]+ (KZnClL = [ZnClL+]/[Zn2+][Cl-][L] = 107.2 ± 0.1 M-2;d3-
甲醇,301 K)。