Boronic acids as fructose sensors. Structure determination of the complexes involved using (1)J(CC) coupling constants
Boronic acids as fructose sensors. Structure determination of the complexes involved using (1)J(CC) coupling constants
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DOI：
10.1039/p29960002583
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发表时间：
1996-12-01
期刊：
影响因子：
--
通讯作者：
Eggert, H
中科院分区：
文献类型：
--
作者：
Norrild, JC;Eggert, H
利用C-13核磁共振波谱研究了中性非水溶液和碱性水溶液中对甲苯基硼酸与D-果糖形成络合物的情况，以评价基于硼酸的果糖传感器的可能性。在这两种条件下都观察到了络合物的混合物。根据(T)J(CC)偶合常数确定了配合物在溶液中的结构，为形成的环状硼酸酯提供了结合部位的信息。在碱性水溶液中，观察到7种不同的络合物。当硼酸与果糖之比为1：1时，主要络合物(82%)为β-D-呋喃果糖2，3，6-三-O-(对甲苯基正硼酸)1。次要络合物为β-D-呋喃果糖2，3-(对甲苯基羟基硼酸酯)，以2a和2b两种非对映异构体形式存在。在较高的硼酸/果糖比下，还观察到四种可能的β-D-果糖2，3：4，5-二(对甲苯基羟基硼酸酯)3a-d的非对映异构体。在非水条件下，观察到13种不同化合物的信号。这些复合体中有五个在结构上被指定。当硼酸与果糖的比例为1：1时，主要的络合物是β-D-呋喃果糖2，3(对甲苯基硼酸酯)5，占46%。在4：1的比例下，主要物种为β-D-果糖2，3：4，5-二(对甲苯基硼酸酯)7，占67%。还观察到两个单酯化的吡喃糖和一个呋喃糖。归属为β-D-吡喃果糖1，2-(对甲苯基硼酸酯)8、α-D-吡喃果糖1，3-(对甲苯基硼酸酯)9和β-D-呋喃果糖1，3-(对甲苯基硼酸酯)6。
Complex formation between p-tolylboronic acid and D-fructose was investigated by C-13 NMR spectroscopy both in neutral nonaqueous and alkaline aqueous solutions to evaluate the possibilities of boronic acid based fructose sensors. Under both conditions a mixture of complexes was observed. The structures of the complexes in solution were assigned on the basis of (t)J(CC) coupling constants which provided the information of the binding sites for the formed cyclic boronic esters. In alkaline aqueous solution seven different complexes were observed. At a 1:1 boronic acid:fructose ratio the major complex (82%) was beta-D-fructofuranose 2,3,6-tri-O-(p-tolylorthoboronate) 1. The minor complex was beta-D-fructofuranose 2,3-(p-tolylhydroxyboronate) present in two diastereomeric forms 2a and 2b. At higher boronic acid:fructose ratios four additional complexes were observed namely the four possible diastereomeric forms of beta-D-fructopyranose 2,3:4,5-bis(p-tolylhydroxyboronate) 3a-d. Under nonaqueous conditions signals arising from 13 different compounds were observed. Five of these complexes were structurally assigned. At a 1:1 boronic acid:fructose ratio the major complex was beta-D-fructofuranose 2,3(p-tolylboronate) 5 present in 46%. At a ratio of 4:1 the major species was beta-D-fructopyranose 2,3:4,5-bis(p-tolylboronate) 7 present in 67%. Two additional monoesterified pyranoses and one furanose were observed. They were assigned to the beta-D-fructopyranose1,2-(p-tolylboronate) 8, the alpha-D-fructopyranose 1,3-(p-tolylboronate) 9 and the beta-D-fructofuranose 1,3-(p-tolylboronate) 6. It is concluded that results of earlier studies on binding constants bear no relation to the actual formed complexes.