The CH/π hydrogen bond is the weakest extreme of hydrogen bonds that occurs between a soft acid CH and a soft base π-system (Figure).[1] The implication in chemistry includes issues of conformation, crystal packing, and specificity in lattice and cavity inclusion complexes. The results obtained by analyzing the Cambridge Structural Database (CSD) will be reviewed.[2] The role of CH/π hydrogen bonds in biomacromolecules[3] will be briefly presented. Recent high-level ab initio MO calculations have provided evidence that specific protein/substrate interactions and folded conformations reported for natural organic compounds such as α-phellandrene is explained in terms of CH/π hydrogen bonds.[4] This will be presented, if time allows.
References:
1. Nishio, M., Hirota, M., Umezawa, Y., The CH/π interaction. Evidence, Nature, and Consequences, 1998, Wiley-VCH, New York; Nishio, M., Hirota, M. Tetrahedron 1989, 45, 7201-7245; Nishio, M. et al., Tetrahedron 1995, 51, 8665-8701; Nishio, M., CrystEngComm 2004, 6, 130-156; Nishio, M. et al., CrystEngComm 2009, 11, 1757-1788.
2. Umezawa. Y. et al., Bull. Chem. Soc. Jpn. 1998, 71, 1207-1213; Takahashi, H. et al., Tetrahedron 1999, 55, 10047-10056; Umezawa, Y. et al., Bioorg. Med. Chem. 1999, 7, 2021-2026; Takahashi, H. et al., Tetrahedron 2000, 56, 6185-6191; Suezawa, H. et al., J. Chem. Soc. Perkin Trans. 2 2001, 2053-2058; Takahashi, O. et al., Bull. Chem. Soc. Jpn. 2001, 74, 2421-2430; Suezawa, H. et al., Eur. J. Inorg. Chem. 2002, 3148-3155; Suezawa, H. et al., New J. Chem. 2003, 27, 1609-1613; Suezawa, H. et al., CrystEngComm 2003, 5, 514-518.
3. Umezawa, Y., Nishio, M., Bioorg. Med. Chem. 1998, 6, 493-504; 1998, 6, 2507-2515; 2000, 8, 2643-2650; Umezawa, Y., Nishio, M., Nucleic Acids Res. 2002, 30, 2183-2192; Umezawa, Y., Nishio, M., Biopolymers 2005, 79, 248-258.
4. Takahashi, O. et al., Tetrahedron 2008, 64, 2433-2440; 2008, 64, 5773-5778; 2009, 65, 3525-3528.
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