“…A number of ammonium sulfonates co-crystallize with water, resulting in a balancing of the number of hydrogen-bond donor and acceptor sites in the structure (Banerjee et al, 1984;Andrews et al, 1986;Laks et al, 1986;Marchand et al, 1990;Balasubramanian & Muthiah, 1996;Merritt & Duf®n, 1970). We obtained pyridinium d(+)-10-camphorsulfonate hemihydrate, (I) ( Fig.…”