The 6',6 ''-(2-phenylpyrimidine-4,6-diyl)bis(6-methyl-2,2'-bipyridine) ligand L reacts with trifluoromethanesulfonate silver(I) to give dinuclear helical complex [Ag2L2](CF3SO3)(2)center dot H2O in which metal ions are in approximately heavily flattened tetrahedron coordination geometry. The complex has been characterized by spectroscopic techniques, elemental analysis, transmission and scanning electron microscopies, and thermogravimetry. The solid state structure of complex has been determined by X-ray diffractometry. The methylene blue (MB) degradation was studied with UV-Vis spectrophotometry. A maximum degradation efficiency of 90% of the dye has been achieved. Photodegradation of the dye follows second-order kinetics. [Ag2L2](CF3SO3)(2)center dot H2O is active photocatalyst of MB degradation under UV-Vis and sunlight irradiation. (C) 2012 Elsevier Inc. All rights reserved.