The proficiency of molecule based magnetic materials in controlling their functionalities with external stimuli is an extremely intriguing and appealing trait. A remarkable contribution is attributed to the field of bistable magnetic materials by the spin crossover (SCO) systems where bistability occurs as a result of switching between low-spin (LS) and highspin (HS) states of d 4 -d 7 transition-metal complexes. Extensive studies have been carried out over the years with these SCO systems due to their responses towards various external stimuli such as temperature, pressure, light, pH, electric and magnetic fields to change their physical properties as well as functionalities. Hence, such materials are the great prerequisites for the design of several multifunctional materials including data storage devices, sensors and switches. Among all the categories of spin-crossover systems, Fe(II) complexes having FeN6 environment emerged as a prominent candidate of extensive research due to their remarkable diversity in terms of spin transition characteristics. The distinction between the paramagnetic HS [(t2g) (eg) 2 ] (S = 2) and diamagnetic LS state [(t2g) (eg) 0 ] (S = 0) of these systems can easily be studied by magnetic, optical and structural changes that occurred during the spin-state switching. However, the SCO solely depends on the nature of the ligands, solvent molecules, structural matrix, counter cations / anions, guest molecules etc. Recently, using octacyanometallate building blocks [M IV/V (CN)8] 4-/3-(M = Mo, W, Nb, Re) and SCO active Fe(II) units, we have explored the multifunctional properties of SCO materials that can point towards the development of advanced bistable materials with improved functionalities. Our recent studies revealed that, bimetallic assemblies of extended coordination networks based on octacyanometallate building blocks are good candidates as they can offer eight coordination sites coming from eight cyanide ligands and can have various structural topologies ranging from one dimensional to threedimensional networks. Most importantly, the topology of structures formed by these complexes are extremely variant and shows important physical as well as chemical properties. It is worth noting that very few Fe(II) SCO systems connecting with [Mo IV/V (CN)8] n-building blocks have been reported so far and among them 3D network exhibiting complete SCO property is very rare in the literature. In this regard to design the multifunctional magnetic material we have synthesized a novel 3D cyanide-bridged hexagonal coordination network based on octacyanometallate building block which exhibits solvent-Please do not adjust margins Please do not adjust margins triggered reversible spin-state switching and Light-Induced Excited Spin State Trapping (LIESST) effect at low temperature. Applying complex as ligand strategy, herein we used octacyanometallate (HNBu3)3[Mo V (CN)8] building block to prepare a 3D hexagonal coordination network of formula {