Host-guest complexes of cucurbituril with 4-amino-4′-nitroazobenzene and 4,4′-diaminoazobenzene in acidic aqueous solutions

被引:38
作者
Neugebauer, R [1 ]
Knoche, W [1 ]
机构
[1] Univ Bielefeld, Fak Chem, D-33501 Bielefeld, Germany
来源
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1998年 / 03期
关键词
D O I
10.1039/a708015h
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The thermodynamics and kinetics of the reaction of cucurbituril (Cuc) with 4-amino-4'-nitroazobenzene (DO3) and 4,4'-diaminoazobenzene (Diam) have been studied in aqueous HCl, and it is shown that DO3 is well suited as an indicator for uncomplexed Cuc (actual concentration of Cue) and Diam is well suited as an indicator for the total concentration of Cuc (sequestering agent) in aqueous solutions. The formation of 1:1 guest-host complexes is observed. For proton concentrations up to 1 mol dm(-3), DO3 reacts according to eqn. (a), with the values for the dissociation constant of DO3H(+) log(K-a/dm(3) mol(-1)) = CucH(+) + DO3H(2)(2+) reversible arrow CucH(+) + DO3H(+) + H+ reversible arrow CucH(+) + DO3 + 2H(+) reversible arrow CucDO3H(+) + 2H(+) (a) -2.42, DO3H(2)(2+) log(K-b/dm(3) mol(-1)) = 0.53, for the stability constant of CucDO3H(+) log (K-c/mol dm(3)) = 8.05 and for the rate constant of complex formation log (k(f)/dm(3) mol(-1) s(-1)) = 5.25. Reaction enthalpies and activation energies have also been determined. The complexation of Cuc with Diam has been studied in 0.1-1 mol dm(-3) HCl where a very strong complexation has been observed.
引用
收藏
页码:529 / 534
页数:6
相关论文
共 7 条
[1]   A SYSTEMATIC ENTROPY RELATIONSHIP FOR THE GENERAL-BASE CATALYSIS OF THE DEPROTONATION OF A CARBON ACID - A QUANTITATIVE PROBE OF TRANSITION-STATE SOLVATION [J].
BUNTING, JW ;
STEFANIDIS, D .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1990, 112 (02) :779-786
[2]   CUCURBITURIL - SUPRAMOLECULAR PERSPECTIVES FOR AN OLD LIGAND [J].
CINTAS, P .
JOURNAL OF INCLUSION PHENOMENA AND MOLECULAR RECOGNITION IN CHEMISTRY, 1994, 17 (03) :205-220
[3]  
Davies W. C., 1962, ION ASS
[4]   HOST-GUEST COMPLEXES OF CUCURBITURIL WITH THE 4-METHYLBENZYLAMMONIUM ION, ALKALI-METAL CATIONS AND NH4+ [J].
HOFFMANN, R ;
KNOCHE, W ;
FENN, C ;
BUSCHMANN, HJ .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 1994, 90 (11) :1507-1511
[5]  
MOCK L, 1995, TOP CURR CHEM, V175
[6]  
Robinson R. A., 1970, ELECTROLYTE SOLUTION
[7]  
1978, CRC HDB CHEM PHYSICS