A supramolecular receptor of diatomic molecules (O2, CO, NO) in aqueous solution
A supramolecular receptor of diatomic molecules (O2, CO, NO) in aqueous solution
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DOI：
10.1021/ja8009583
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发表时间：
2008-06-25
影响因子：
15
通讯作者：
Hirota, Shun
中科院分区：
文献类型：
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作者：
Kano, Koji;Itoh, Yoshiki;Hirota, Shun
全O-甲基化β-环糊精二聚体Py2CD可通过两个步骤方便地制备：3,5-双(溴甲基)吡啶和β-环糊精(β-CD)进行Williamson反应，产生2A,2'A-O-[3,5-吡啶二基双(亚甲基)双-β-环糊精(bisCD)，然后将bisCD的所有羟基进行O-甲基化。 Py2CD 与[5,10,15,20-四(对磺酸基苯基)卟啉]铁(III) ((FeTPPS)-T-II) 在水溶液中形成非常稳定的1:1 络合物(Fe(III)PCD)。 Fe(III)PCD 用 Na2S2O4 还原，得到 (FeTPPS)-T-II/Py2CD 复合物 (Fe(II)PCD)。双氧与 Fe(II)PCD 结合，3 摄氏度和 25 摄氏度下的 P-1/2(O2) 值分别为 42.4 +/- 1.6 和 176 +/- 3 Torr。在 25 摄氏度下，分子氧结合的 k(on)(O2) 和 k(off) (O2) 值分别确定为 1.3 x 10(7) M(-1)s(-1) 和 3.8 x 10(3) s(-1)。尽管分子氧加合物不是很稳定 (K-O2 = k(on)(O2) /k(off)(O2) = 3.4 x 10(3) M-1)，没有观察到 Fe(II)PCD 的双氧加合物到 Fe(III)PCD 的自氧化。这些结果表明，Py2CD 对 (FeTPPS)-T-II 的封装不仅严格抑制双氧从环糊精笼中挤出，而且还严格抑制水分子渗透到笼中。 Fe(II)PCD的一氧化碳亲和力远高于分子氧亲和力； 25 度时，P-1/2(CO)、k(on)(CO)、k(off)(CO) 和 K-CO 值分别为 (1.6 +/- 0.2) x 10(-2) Torr、2.4 x 106 M(-1)s(-1)、4.8 x 10(-2) s(-1) 和 5.0 x 10(7) M-1 C. Fe(II)PCD 也结合一氧化氮。 NO从(NO)Fe(II)PCD解离的速率((5.58+/-0.42)×10(-1)s(-1))与(NO)Fe(II)PCD氧化成Fe(III)PCD和NO3-的最大速率((5.12+/-0.18)×10(-5)S-1)非常一致，表明NO的自氧化(NO)Fe(II)PCD 通过 NO 和 O-2 之间的配体交换进行，然后 (O-2)Fe(II)PCD 与释放的 NO 快速反应，在环糊精笼内提供 Fe(II)PCD 和 NO3- 阴离子。
A per-O-methylated beta-cyclodextrin dimer, Py2CD, was conveniently prepared via two steps: the Williamson reaction of 3,5-bis(bromomethyl)pyridine and beta-cyclodextrin (beta-CD) yielding 2A,2'A-O-[3,5-pyridinediylbis(methylene) bis-beta-cyclodextrin (bisCD) followed by the O-methylation of all the hydroxy groups of the bisCD. Py2CD formed a very stable 1:1 complex (Fe(III)PCD) with [5,10,15,20-tetrakis(psulfonatophenyl)porphinato]iron(III) ((FeTPPS)-T-II) in aqueous solution. Fe(III)PCD was reduced with Na2S2O4 to afford the (FeTPPS)-T-II/Py2CD complex (Fe(II)PCD). Dioxygen was bound to Fe(II)PCD, the P-1/2(O2) values being 42.4 +/- 1.6 and 176 +/- 3 Torr at 3 and 25 degrees C, respectively. The k(on)(O2) and k(off) (O2) values for the dioxygen binding were determined to be 1.3 x 10(7) M(-1)s(-1) and 3.8 x 10(3) s(-1), respectively, at 25 degrees C. Although the dioxygen adduct was not very stable (K-O2 = k(on)(O2) /k(off)(O2) = 3.4 x 10(3) M-1), no autoxidation of the dioxygen adduct of Fe(II)PCD to Fe(III)PCD was observed. These results suggest that the encapsulation of (FeTPPS)-T-II by Py2CD strictly inhibits not only the extrusion of dioxygen from the cyclodextrin cage but also the penetration of a water molecule into the cage. The carbon monoxide affinity of Fe(II)PCD was much higher than the dioxygen affinity; the P-1/2(CO), k(on)(CO), k(off)(CO), and K-CO values being (1.6 +/- 0.2) x 10(-2) Torr, 2.4 x 106 M(-1)s(-1), 4.8 x 10(-2) s(-1), and 5.0 x 10(7) M-1, respectively, at 25 degrees C. Fe(II)PCD also bound nitric oxide. The rate of the dissociation of NO from (NO)Fe(II)PCD ((5.58 +/- 0.42) x 10(-1) s(-1)) was in good agreement with the maximum rate ((5.12 +/- 0.18) X 10(-5) S-1) of the oxidation of (NO)Fe(II)PCD to Fe(III)PCD and NO3-, suggesting that the autoxidation of (NO)Fe(II)PCD proceeds through the ligand exchange between NO and O-2 followed by the rapid reaction of (O-2)Fe(II)PCD with released NO, affording Fe(II)PCD and the NO3- anion inside the cyclodextrin cage.