@article{open2427,
          volume = {13},
          number = {5},
           month = {April},
          author = {Muthusamy Ramesh and Prasad V Bharatam and P Venugopalan and Raghuvansh Kishore},
            note = {opyright of this article belongs to ACS.},
           title = {Importance of C?H???O Intramolecular Hydrogen Bonding Across a Nonproteinogenic {\ensuremath{\gamma}}-Aminobenzoic Acid Residue: Stabilization of a Flat {\ensuremath{\beta}}-Strand-like Template},
       publisher = {American Chemical Society},
            year = {2013},
         journal = {Crystal Growth \& Design },
           pages = {2004--12},
             url = {http://crdd.osdd.net/open/2427/},
        abstract = {This paper describes the conformational characteristics of a nonproteinogenic {\ensuremath{\gamma}}-aminobenzoic acid ({\ensuremath{\gamma}}-Abz), investigated experimentally as well as theoretically. The single crystal X-ray diffraction analysis of the model system Boc-{\ensuremath{\gamma}}-Abz-NHMe (1) revealed the existence of an unusual {\ensuremath{\beta}}-strand-like molecular structure. The two weak unconventional C?H???O intramolecular hydrogen-bonds, i.e., main-chain to main-chain: C{\ensuremath{\beta}}i+1?H???O?Ci+1 and main-chain to side-chain C{\ensuremath{\delta}}i+1?H???O?Ci interactions, evidently stabilize the flat molecular topology. The favorable antiparallel {\ensuremath{\beta}}-strand mimics are held together by a network of cross-strand N?H???O intermolecular hydrogen bonds. Interestingly, the noncovalent {\ensuremath{\beta}}-sheet-like duplexes facilitate the fabrication of offset face-to-face aromatic?aromatic interactions, whereas the dimers of dimers are aligned edge-to-edge. The two-dimensional 1H NMR ROESY experiment ascertained the extraordinary stability of the rigid {\ensuremath{\beta}}-strand template and molecular self-assembly in a nonpolar environment. The ab initio molecular modeling substantiated the crystal molecular structure as the minimum energy conformer along with weak C?H???O intramolecular hydrogen bonds. The solid-state Fourier transform infrared spectral analysis sustained the participation of both amide-NHs in intermolecular hydrogen bonding. The highly ordered supramolecular architecture, engendered from a single preorganized molecular component, exploited a variety of strong as well as weak stabilizing forces as varied as N?H???O, C?H???O, Ar???Ar, and van der Waals and/or hydrophobic interactions.}
}