Liu Yu, Song Yun, Chen Yong, Li Xue-Qing, Ding Fei, Zhong Rui-Qin
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P.R. China.
Chemistry. 2004 Aug 6;10(15):3685-96. doi: 10.1002/chem.200305724.
A series of bridged beta-cyclodextrin (beta-CyD) dimers possessing functional tethers of various lengths was synthesized in moderate yield by the treatment of 2,2'-biquinoline- 4,4'-dicarboxylic dichloride with beta-CyD or mono[6-oligo(ethylenediamino)-6-deoxy]-beta-CyDs. The products were 2,2'-biquinoline-4,4'-dicarboxy-bridged bis(6-O-beta-CyD) (8), N,N'-bis(2-aminoethyl)-2,2'-biquinoline-4,4'-dicarboxamide-bridged bis(6-amino-6-deoxy-beta-CyD) (9), and N,N'-bis(5-amino-3-azapentyl)-2,2'-biquinoline-4,4'-dicarboxamide-bridged bis(6-amino-6-deoxy-beta-CyD) (10). The reaction of 8-10 with copper perchlorate give their copper(II) complexes 11-13 in satisfactory yields of over 77 %. All the bis(beta-CyD)s 8-13 act as efficient fluorescent sensors and display remarkable fluorescence enhancement upon addition of optically inert steroids. The inclusion complexation behaviors of 8-13 when treated with the representative steroids cholate (14), deoxycholate (15), and glycocholate (16) in aqueous solution at 25 degrees C were investigated by means of UV/Vis spectroscopy, conductivity and fluorescence measurements, circular dichroism spectroscopy, and 2D NMR spectroscopy. The tether length of bis(beta-CyD) 9 allows it to adopt a cooperative host-tether-guest binding mode in which the spacer and guest are co-included in the two CyD cavities. As a result of this cooperation, 9 has a stability constant (K(s)) about 2x10(2) times higher than that of monomodified beta-CyD 4 for inclusion complexation with cholate. Metallooligo(beta-CyD)s with four beta-CyD units have enhanced binding abilities compared with monomodified beta-CyDs. These metallo compounds have binding affinities for guest steroids that are up to 50-4.1x10(3) times higher than those of CyDs 2-4. The guest-induced fluorescence enhancement of bis(CyD)s opens a new channel for the design of sensor materials. The complex stability constants of these compounds are discussed from the viewpoint of induced-fit interaction and cooperative multiple binding between host and guest.
通过用β-环糊精（β-CyD）或单[6-低聚（乙二胺基）-6-脱氧]-β-CyDs处理2,2'-联喹啉-4,4'-二羧酸二氯化物，以中等产率合成了一系列具有不同长度功能连接基的桥连β-环糊精（β-CyD）二聚体。产物为2,2'-联喹啉-4,4'-二羧基桥连双（6-O-β-CyD）（8）、N,N'-双（2-氨基乙基）-2,2'-联喹啉-4,4'-二羧酰胺桥连双（6-氨基-6-脱氧-β-CyD）（9）和N,N'-双（5-氨基-3-氮杂戊基）-2,2'-联喹啉-4,4'-二羧酰胺桥连双（6-氨基-6-脱氧-β-CyD）（10）。8 - 10与高氯酸铜反应，以超过77%的令人满意的产率得到它们的铜（II）配合物11 - 13。所有双（β-CyD）s 8 - 13都作为高效的荧光传感器，并且在加入光学惰性甾体时显示出显著的荧光增强。通过紫外/可见光谱、电导率和荧光测量、圆二色光谱和二维核磁共振光谱研究了8 - 13在25℃水溶液中与代表性甾体胆酸盐（14）、脱氧胆酸盐（15）和甘氨胆酸盐（16）处理时的包合络合行为。双（β-CyD）9的连接基长度使其能够采用一种协同的主体-连接基-客体结合模式，其中间隔基和客体共同包含在两个CyD腔中。由于这种协同作用，9与胆酸盐形成包合络合物的稳定常数（K(s)）比单修饰的β-CyD 4高约2×10(2)倍。与单修饰的β-CyDs相比，具有四个β-CyD单元的金属低聚（β-CyD）s具有增强的结合能力。这些金属化合物对客体甾体的结合亲和力比CyDs 2 - 4高达到50 - 4.1×10(3)倍。双（CyD）s的客体诱导荧光增强为传感器材料的设计开辟了一条新途径。从诱导契合相互作用和主体与客体之间的协同多重结合的角度讨论了这些化合物的络合稳定常数。
