We have demonstrated that the rational assembly of low-coordinate lanthanide single molecule magnets such as [Er III (BHT)3(THF)] with photochromic ligands like 1,2-bis(2-methyl-5-pyridyl)thien-3yl)perfluorocyclopentene (dtepy) in a strictly non-coordinating hydrocarbon solvent is a rational way to multifunctional molecular materials where both desired functionalities -the slow magnetic relaxation and the photoswitching -are retained. Moreover, compound 1 synthesized and investigated within this study demonstrates the influence of the photocyclization of the ligand on the SMM behavior. The observed effect is irreversible due to the loss of crystallinity of the compound, but enables the formulation of a strategy towards new organometallic single molecule magnets with high blocking temperatures that can be controlled by electromagnetic radiation.