The Effect of NaCl on the Conformational Behavior of Acenaphthylene Labeled Poly(N,N-diethylacrylamide) in Dilute Aqueous Solution

✍ Scribed by Yong Chen; Ming-zhu Liu; Feng-ling Bian; Bing Wang; Shi-lan Chen; Shu-ping Jin

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 156 KB
• Volume: 207
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200500416

✦ Synopsis

Abstract

Summary: The effect of salts on the conformational behavior of acenaphthylene labeled poly(N,N‐diethylacrylamide) (PDEA/ACE) has been investigated in dilute aqueous solution using UV‐vis and fluorescence spectroscopy. It is demonstrated here that the effectiveness of various salts in changing the lower critical solution temperature (T~LCS~) of the PDEA/ACE solution followed the Hoffmeister series. The addition of NaCl linearly lowered the T~LCS~. In dilute aqueous solution, the PDEA/ACE adopted a loose coil conformation below its T~LCS~. The PDEA/ACE adopted a compact globule conformation above the temperature at which the coil to globule transition (CGT) was completed. A fluorescence anisotropy investigation suggested that a molten globule conformation existed during the CGT of the PDEA/ACE solution. In all of the above three conformations, the PDEA/ACE was more compact in the presence of NaCl than in the absence of any salt.

Temperature and NaCl concentration dependence of fluorescence anisotropy of a PDEA/ACE solution. Inset: thermodynamically stable states of PDEA/ACE.

imageTemperature and NaCl concentration dependence of fluorescence anisotropy of a PDEA/ACE solution. Inset: thermodynamically stable states of PDEA/ACE.