Synthesis and characterization of a novel, multifunctional, solvent-free room-temperature liquid based on alkylated double-decker lutetium(III) phthalocyanine (Pc2Lu) are described. Lowering of the melting point and viscosity of intrinsically solid Pc2Lu compounds has been achieved through the attachment of flexible, bulky, and long branched-alkyl chains, that is, thio-2-octyldodecyl, to the periphery of the Pc2Lu unit. The embedded Pc2Lu unit maintains its inherent molecular functions, such as spin-active nature and electrochromic behavior in the liquid state. Comparison of the properties with a solid-like Pc2Lu derivative, functionalized with shorter alkyl chains, that is, thio-2-ethylhexyl, underlines the importance of the hampering effect on the π–π interactions of neighboring Pc2Lu molecules by bulkier and longer branched-alkyl chains. This study could possibly pave the way for novel multifunctional liquids whose spin-activities are associated with their rheological or optoelectronic properties.