We report a new triarylmethyl carbocation radical which was easily synthesized via "one-pot" approach. Interestingly, this "cis" triarylmethyl carbocation radical converted to the "trans" one upon protonation. Such an obviously conformational change is triggered by the intermolecular hydrogen bond interaction involving one exocyclic "keto" oxygen atom and the protonated pyridinium nitrogen atom. Two triarylmethyl carbocation radical crystals were characterized by the elemental analysis and single crystal X-ray diffraction. A change in conformation also brings about change in crystal structure, phosphorescence and magnetic susceptibility properties. (C) 2016 Elsevier B.V. All rights reserved.