We are interested to study structural modifications in single crystals of the luminescent compound [Cu4(PCP) 3]+ BF4- using high-pressure X-ray diffraction (HP XRD), eventually aiming to correlate the alteration of the photoluminescent properties of the cluster with the structure evolution under mechanical stress. We anticipate that pressure may significantly change or enhance luminescent properties of the studied compound as the Cu···Cu intramolecular distance is one of the shortest ever reported. The further contraction has the potential to develop new optical properties of this compound, as it has been already demonstrated for some noble-metal complexes.