Complex formation of amino polyphosphonates. 1. Potentiometric and nuclear magnetic resonance studies of nitrilotris(methylenephosphonato) complexes of the alkaline-earth-metal ions

1987 ◽  
Vol 26 (8) ◽  
pp. 1199-1204 ◽  
Author(s):  
Kiyoshi Sawada ◽  
Tsutomu Araki ◽  
Toshio Suzuki

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.



2021 ◽  
Author(s):  
Chengming Shang ◽  
Pascal Reiller

The complex formation of triscarbonatouranyl(VI) UO2(CO3)34- with alkaline earth metal ions Mg2+ and Ca2+ in 0.10 mol kgw-1 NaCl were studied at variable temperatures: 5-30°C for Mg2+ and 10-50°C for...



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