Study of γ-cyclodextrin host-guest complex and nanotube aggregate by fluorescence correlation spectroscopy.
J Phys Chem B
; 115(35): 10456-61, 2011 Sep 08.
Article
in En
| MEDLINE
| ID: mdl-21806026
ABSTRACT
Fluorescence correlation spectroscopy (FCS) has been used to study the formation of large nanotube aggregates involving γ-cyclodextrin (γ-CD) and coumarin 153 (C153). It is observed that the length of a γ-CDC153 nanotube aggregate is â¼770 nm. This is â¼480 times larger than the length of a 11 γ-CDC480 complex (â¼1.6 nm) and â¼950 times that of a γ-CD. This implies that 950 γ-CD units are noncovalently attached in the γ-CDC153 aggregate. Binding constants (K(b)) of both the dyes to γ-CD were obtained from the fluctuation in fluorescence intensity. The rate of association and dissociation are obtained from the inverse of τ(off) and τ(on), respectively. The binding constant for the 11 γ-CDC480 complex is â¼1000 M(-1). The burst integrated fluorescence lifetime (BIFL) histogram reveals presence of three distinct lifetime 1.8 ns (18%), 2.8 ns (69%), 3.2 ns (13%). These three lifetimes correspond to C153 present in bulk water and at the end and middle of the γ-CDC153 nanotube aggregate, respectively. The lifetime of C480 in the 11 γ-CDC480 complex is found to be 3.7 ns.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Phys Chem B
Journal subject:
QUIMICA
Year:
2011
Document type:
Article
Affiliation country:
India