This is the author version of a paper published as: Smith, G., Wermuth, U. D., Young, D. J., and Healy, P. C., "Strychnine-8-Ammonio- 2-naphthalenesulfonate-water (1/1/3.5): The First Structure of a Strychnine Compound with a Zwitterionic Species," J. Chem. Crystallogr., 2006, 36 , 805-811 Copyright 2006 Springer Strychnine-8-ammonio-2-naphthalenesulfonate-water (1/1/3.5): The first structure of a strychnine or brucine compound with a zwitterionic species Graham Smith 1 , Urs D. Wermuth 1 , Peter C. Healy 2 and David J. Young 2 (1) School of Physical and Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane, Qld. 4001, Australia (2) School of Science, Griffith University, Nathan, Qld. 4111, Australia Graham Smith - Email: g.smith@qut.edu.au Abstract: The crystal structure of the 1:1 adduct hydrate of strychnine with 1,7- Cleve's acid (8-amino-2-naphthalenesulfonic acid), namely strychnine-8-ammonio-2- naphthalenesulfonate-water (1/1/3.5) has been determined and provides a unique example of a neutral association involving strychnine and an achiral zwitterionic acid species, previously unobserved in the structures of either strychnine or brucine addition compounds. Crystals are orthorhombic, space group P2 1 2 1 2 1 , with Z=4 in a cell with dimensions a=10.4484(8), b=30.850(3), c=9.4998(11) Å. Hydrogen bonding involving all available proton-donor and acceptor sites on all species gives rise to a three-dimensional framework polymer structure. The crystallographic literature for strychnine and brucine and their compounds is also reviewed. KEY WORDS: strychnine - 1,7-Cleve's acid - naphthylaminesulfonic acids - molecular adduct - hydrogen bonding Introduction The alkaloids strychnine (strychnidin-10-one) and brucine (2,3-dimethoxystrychnidin- 10-one) were first used by Fischer1 in 1899 for the separation of enantiomeric mixtures of optically active amino acids (as their N-benzoyl-protected derivatives). Since that time both of these alkaloids have been variously employed on a hit-or-miss basis for the resolution of chiral organic compounds, although of the two, brucine has proved to be the better one.