Capillary electrophoresis (CE) has been applied for determination of the thermodynamic acidity constants (pK_a) of the sulfamidoalkyl and sulfonamidoalkyl groups, the actual and limiting ionic mobilities and hydrodynamic radii of important compounds, eight carborane‐based inhibitors of carbonic anhydrases, which are potential new anticancer drugs. Two types of carboranes were investigated, (i) icosahedral cobalt bis(dicarbollide)(1‐) ion with sulfamidoalkyl moieties, and (ii) 7,8‐nido‐dicarbaundecaborate with sulfonamidoalkyl side chains. First, the mixed acidity constants, pK_a^mix, of the sulfamidoalkyl and sulfonamidoalkyl groups of the above carboranes and their actual ionic mobilities were determined by nonlinear regression analysis of the pH dependences of their effective electrophoretic mobility measured by capillary electrophoresis in the pH range 8.00−12.25, at constant ionic strength (25 mM), and constant temperature (25°C). Second, the pK_a^mix were recalculated to the thermodynamic pK_as using the Debye–Hückel theory. The sulfamidoalkyl and sulfonamidoalkyl groups were found to be very weakly acidic with the pK_as in the range 10.78−11.45 depending on the type of carborane cluster and on the position and length of the alkyl chain on the carborane scaffold. These pK_as were in a good agreement with the pK_as (10.67−11.27) obtained by new program AnglerFish (freeware at https://echmet.natur.cuni.cz), which provides thermodynamic pK_as and limiting ionic mobilities directly from the raw CE data. The absolute values of the limiting ionic mobilities of univalent and divalent carborane anions were in the range 18.3−27.8 TU (Tiselius unit, 1 × 10⁻⁹ m²/Vs), and 36.4−45.9 TU, respectively. The Stokes hydrodynamic radii of univalent and divalent carborane anions varied in the range 0.34−0.52 and 0.42−0.52 nm, respectively.

中文翻译：

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毛细管电泳法测定碳硼烷基碳酸酐酶抑制剂的酸度常数、离子迁移率和流体动力学半径

毛细管电泳 (CE) 已用于测定磺酰胺烷基和磺酰胺烷基的热力学酸度常数 (p Ka )、重要化合物的实际和限制离子迁移率和流体动力学半径，八种基于碳硼烷的碳酸酐酶_抑制剂，是潜在的新型抗癌药物。研究了两种类型的碳硼烷，（i）具有磺酰胺烷基部分的二十面体钴双（二碳化物）（1-）离子，和（ii）具有磺酰胺烷基侧链的7,8- nido- dicarbaundecaborate。一、混合酸度常数，p K _a ^mix，上述碳硼烷的磺酰氨基烷基和磺酰氨基烷基中的磺酰氨基烷基和它们的实际离子迁移率是通过对其有效电泳迁移率的 pH 依赖性的非线性回归分析来确定的，这些迁移率是通过毛细管电泳在 8.00-12.25 的 pH 范围内测量的，在恒定的离子强度（25 mM ) 和恒温 (25°C)。其次，使用 Debye-Hückel 理论将 p K _a^混合物重新计算为热力学 p K _{a s。}根据碳硼烷簇的类型以及碳硼烷支架上烷基链的位置和长度，发现磺胺烷基和磺胺烷基具有非常弱的酸性，p Ka s 在 10.78-11.45 范围内_。这些 p K_a s 与新程序 AnglerFish（https://echmet.natur.cuni.cz 上的免费软件）获得的 p Ka s (10.67−11.27) 非常一致，该程序提供热力学 p Ka _s和_限制离子迁移率直接来自原始 CE 数据。一价和二价碳硼烷阴离子的极限离子迁移率的绝对值分别在 18.3-27.8 TU（Tiselius 单位，1 × 10 ^-9 m ² /Vs）和 36.4-45.9 TU 范围内。一价和二价碳硼烷阴离子的斯托克斯流体动力学半径分别在 0.34-0.52 和 0.42-0.52 nm 范围内变化。