Close integration of metal nanoparticles (NPs) into a metal-organic framework (MOF) can be leveraged to achieve tailored functionality of the resulting composite structure. Here, we demonstrate a "ship-in-a-bottle" approach to produce ≈4.0 nm bismuth (Bi) NPs within a thiol-rich zirconium-based MOF of Zr-DMBD (DMBD = 2,5-dimercapto-1,4-benzenedicarboxylate). We found that the incorporation of Bi NPs into the Zr-DMBD framework relies on the free-standing thiol groups. These thiols have two roles - (i) aid in binding precursor Bi