Structural Study of Salicylic Acid Salts of a Series of Azacycles and Azacrown Ethers

Interaction of salicylic acid (saH) with the azacycles piperidine (pipe) and meso-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (teta) and with the aza-crown ethers aza-12-crown-4 (A12C4), benzoaza-15-crown-5 (BA15C5), aza-18-crown-6 (A18C6), and diaza-18-crown-6 (DA18C6) afforded the proton-transfer complexes (organic salts) of compositions [pipeH][sa], [tetaH2][sa]2, [A12C4H][sa], [BA15C5H][sa], [A18C6H][sa]·2H2O, and [DA18C6H2][sa]2·3H2O, whose structures were determined by a single crystal X-ray method. These products were also obtained by the same synthetic conditions starting from acetylsalicylic acid (aspirin) as a result of hydrolysis. The charge-assisted N−H···O hydrogen-bond provides the main driving force for direct binding of sa with cyclic azonia cations. The crystal packing is also supported by weak C−H···O hydrogen bonding and edge-to-face π···π intermolecular interactions.