“…ETN crystallizes in space group Cc [ 22 ], without any polymorphic forms known to date. On the other hand, there are several examples in the literature of salts and cocrystals of ETN, namely ETN hydrochloride [ 23 ], hydrobromide [ 24 ], nitrate [ 25 ], oxalate [ 26 , 27 ], maleate [ 27 ] and saccharinate [ 27 ]; ETN·adipic acid [ 26 ], ETN·fumaric acid [ 26 ] and ETN·suberic acid [ 26 ]. Notably, in all salts reported in the literature, N5 of ETN appears to be protonated, while in all cocrystal structures of ETN with carboxylic acids, the COOH group is involved in hydrogen bond (HB) contacts with both N5 (COOH···N) and N10 (C=O···HN).…”