We herein report two crystals based on 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical and its perchlorate, and investigate the relationship between magnetic properties and crystal stacking structures or supramolecular interactions. 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical in two crystals mainly exist as diamagnetic dimer formed via short atomic contacts or supramolecular interactions (hydrogen bonds, anion-π or lonepair-π interactions), leading to low magnetic susceptibilities. 2-(imidazo[1,2-a]pyridin-2-yl)-2-oxoacetic acid radical crystal exhibits quasi-one-dimensional columnar stacking chain and weak antiferromagnetism. However, its perchlorate crystal possesses one-dimensional doublestranded chain structure assembled through double hydrogen bonds and anion-π interactions, and reveals weak ferromagnetism.