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Molecular Recognition of Bridged Bis(β‐cyclodextrin) s Linked by Phenylenediseleno Tether on the Primary or Secondary Side with Fluorescent Dyes
Author(s) -
Li Li,
He Song,
Liu Yu
Publication year - 2003
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.20030210748
Subject(s) - chemistry , cyclodextrin , binding constant , fluorescence , dimer , stability constants of complexes , molecule , hydrophobic effect , molecular binding , aqueous solution , rhodamine b , crystallography , gibbs free energy , acridine , fluorescence spectroscopy , stereochemistry , binding site , organic chemistry , biochemistry , physics , quantum mechanics , photocatalysis , catalysis
Abstract A novel β‐cyclodextrin dimer, 2, 2′‐ o ‐phenylenediseleno‐bridged bis (β‐cyclodextrin) (2), has been synthesized by reaction of mono‐[2‐ O ‐( p ‐tolylsulfonyl)]‐β‐cyclodextrin and poly( o ‐phenylenediselenide). The complexation stability constants (K 2 ) and Gibbs free energy changes (‐Δ G °) of dimer 2 with four fluorescence dyes, that is, ammonium 8‐anilino‐1‐naphthalenesulfonate (ANS), sodium 6‐( p ‐toluidino)‐2‐naphthalenesulfonate (TNS), Acridine Red (AR) and Rhodamine B (RhB) have been determined in aqueous phosphate buffer solution (pH = 7.2, 0.1 mol‐L −1 ) at 25 °C by means of fluorescence spectroscopy. Using the present results and the previously reported corresponding data of β‐cyclodextrin (1) and 6, 6′‐ o ‐phenylenediseleno‐bridged bis (β‐cyclodextrin) (3), binding ability and molecular selectivity are compared, indicating that the bis (β‐cyclodextrin)s 2 and 3 possess much higher binding ability toward these dye molecules than parent β‐cyclodextrin 1, but the complex stability constant for 2 linked from the primary side is larger than that of 3 linked from the secondary side, which is attributed to the more effective cooperative binding of two hydrophobic cavities of host 3 and the size/shape‐fit relationship between host and guest. The binding constant (K 2 ,) upon inclusion complexation of host 3 and AR is enhanced by factor of 27.3 as compared with that of 1. The 2D 1 H NOESY spectrum of host 2 and RhB is performed to confirm the binding mode and explain the relative weak binding ability of 2.