Selective complexation of N-alkylpyridinium salts: binding of NAD+ in water.
A new class of receptor molecules is presented that is highly selective for N-alkylpyridinium ions and electron-poor aromatics. Its key feature is the combination of a well-preorganized molecular clip with an electron-rich inner cavity and strategically placed, flanking bis-phosphonate monoester anions. This shape and arrangement of binding sites attracts predominantly flat electron-poor aromatics in water, binds them mainly by pi-cation, pi-pi, CH-pi, and hydrophobic interactions, and leads to their highly efficient desolvation. NAD(+) and NADP, the important cofactors of many redox enzymes, are recognized by the new receptor molecule, which embraces the catalytically active nicotinamide site and the adenine unit. Even nucleosides such as adenosine are likewise drawn into the clip's cavity. Complex formation and structures were examined by one- and two-dimensional NMR spectroscopy, Job plot analyses, and isothermal titration microcalorimetric (ITC) measurements, as well as quantum chemical calculations of (1)H NMR shifts. The new receptor molecule is a promising tool for controlling enzymatic oxidation processes and for DNA chemistry.
Fokkens
Michael
M
Fachbereich Chemie der Universität Marburg, 35032 Marburg, Germany.
Jasper
Christian
C
Schrader
Thomas
T
Koziol
Felix
F
Ochsenfeld
Christian
C
Polkowska
Jolanta
J
Lobert
Matthias
M
Kahlert
Björn
B
Klärner
Frank-Gerrit
FG
D002151:Calorimetry; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004164:Diphosphonates / Q000737:chemistry; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009010:Monte Carlo Method; D009243:NAD / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014867:Water / Q000737:chemistry
D004164:Diphosphonates; D007202:Indicators and Reagents; D011726:Pyridinium Compounds; D014867:Water; D009243:NAD; D004247:DNA