Hydrogen-bonded networks in trans-3-(3-pyridyl)acrylic acid and rctt-3,3′-(3,4-dicarboxycyclobutane-1,2-diyl)-dipyridinium dichloride

The structure of trans- 3-( 3- pyridyl) acrylic acid, C8H7NO2, ( I), possesses a two- dimensional hydrogen- bonded array of supramolecular ribbons assembled via heterodimeric synthons between the pyridine and carboxyl groups. This compound is photoreactive in the solid state as a result of close contacts between the double bonds of neighbouring molecules [ 3.821 ( 1) A] along the a axis. The crystal structure of the photoproduct, rctt- 3,3'( 3,4- dicarboxycyclobutane- 1,2- diyl)dipyridinium dichloride, C16H16N2O4 (2+) center dot 2Cl(-), ( II), consists of a three- dimensional hydrogen- bonded network built from crosslinking of helical chains integrated by self- assembly of dipyridinium cations and Cl. anions via different O - H center dot center dot center dot Cl, C - H center dot center dot center dot Cl and N+ - H center dot center dot center dot Cl hydrogen- bond interactions.