7Li, 23Na and 9Be nuclear magnetic resonance investigations of the influence of N-substitution on the solvation interaction of amides with alkali and alkaline earth metal ions

Author(s):  
Bernd M. Rode ◽  
Thomas Pontani ◽  
Gernot Heckmann
2011 ◽  
Vol 89 (7) ◽  
pp. 835-844 ◽  
Author(s):  
Irene C.M. Kwan ◽  
Yi-Min She ◽  
Gang Wu

We report structural determination of cation-templated self-assembly of a guanosine derivative, 2′,3′,5′-O-triacetylguanosine (TAG), in the presence of three alkaline earth metal ions (Ca2+, Sr2+, and Ba2+) in CDCl3. Using a combination of nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) methods, we have found that TAG molecules form discrete octamers in the form of [TAG]8M2+ (M2+ = Ca2+, Sr2+, and Ba2+), which is composed of two G-quartets and a sandwiched metal ion. We have determined the ability of the three alkaline earth metal ions to promote TAG self-assembly (relative binding affinity) to be Sr2+ ≫ Ba2+ > Ca2+. More importantly, we have used two-dimensional (2D) NMR methods to determine the structural details of [TAG]8Sr2+. In particular, we found that each octamer consists of an all-anti G-quartet stacking on top of an all-syn G-quartet in a tail-to-head fashion with a twist angle of 45° between the two G-quartets. This TAG octamer structure represents a unique case quite different from other lipophilic guanosine octamers reported in the literature.


2011 ◽  
Vol 50 (15) ◽  
pp. 6956-6964 ◽  
Author(s):  
Wen-Jian Chen ◽  
Da-Hai Yu ◽  
Xin Xiao ◽  
Yun-Qian Zhang ◽  
Qian-Jiang Zhu ◽  
...  

Author(s):  
Yiran Wang ◽  
Wen Zhang ◽  
Xianjie Zeng ◽  
Tao Deng ◽  
Jianyou Wang

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