Proton-Selective 17O-1H Distance Measurements in Fast Magic-Angle-Spinning Solid-State NMR Spectroscopy for the Determination of Hydrogen Bond Lengths

Abstract

We present a proton-selective method to determine 17O-1H distances in organic, biological and biomimetic materials by fast magic-angle-spinning (MAS) solid-state NMR spectroscopy. This method allows the determination of internuclear distances between specific (17O, 1H) spin pairs selectively. In this way medium-range 17Oâââ1H distances across hydrogen bonds can be estimated in the presence of short-range 17O-1H contacts sharing the same 17O site. The method employs the newly developed symmetry-based radio-frequency (rf) pulse sequence SR412 applied to the protons to achieve heteronuclear dipolar recoupling, while simultaneously decoupling the homonuclear proton dipolar interactions. Fast MAS (50 kHz) and high static magnetic fields (18.8 T) achieve the required proton spectral resolution. Hydrogen bonding is an essential component of the structure and functioning of bio(mimetic) materials.1 17O solid-state NM