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Abstract Silver cluster‐based solids have garnered considerable attention owing to their tunable luminescence behavior. While surface modification has enabled the construction of stable silver clusters, controlling interactions among clusters at the molecular level has been challenging due to their tendency to aggregate. Judicious choice of stabilizing ligands becomes pivotal in crafting a desired assembly. However, detailed photophysical behavior as a function of their cluster packing remained unexplored. Here, we modulate the packing pattern of Ag₁₂clusters by varying the nitrogen‐based ligand. CAM‐1 formed through coordination of the tritopic linker molecule and NC‐1 with monodentate pyridine ligand; established via non‐covalent interactions. Both the assemblies show ligand‐to‐metal‐metal charge transfer (LMMCT) based cluster‐centered emission band(s). Temperature‐dependent photoluminescence spectra exhibit blue shifts at higher temperatures, which is attributed to the extent of the thermal reverse population of the S₁state from the closely spaced T₁state. The difference in the energy gap (ΔE_ST) dictated by their assemblies played a pivotal role in the way that Ag₁₂cluster assembly in CAM‐1 manifests a wider ΔE_STand thus requires higher temperatures for reverse intersystem crossing (RISC) than assembly of NC‐1. Such assembly‐defined photoluminescence properties underscore the potential toolkit to design new cluster‐ assemblies with tailored optoelectronic properties. 

Abstract High quantum yield triplets, populated by initially prepared excited singlets, are desired for various energy conversion schemes in solid working compositions like porous MOFs. However, a large disparity in the distribution of the excitonic center of mass, singlet‐triplet intersystem crossing (ISC) in such assemblies is inhibited, so much so that a carboxy‐coordinated zirconium heavy metal ion cannot effectively facilitate the ISC through spin‐orbit coupling. Circumventing this sluggish ISC, singlet fission (SF) is explored as a viable route to generating triplets in solution‐stable MOFs. Efficient SF is achieved through a high degree of interchromophoric coupling that facilitates electron super‐exchange to generate triplet pairs. Here we show that a predesigned chromophoric linker with extremely poor ISC efficiency (k_ISC) butform triplets in MOF in contrast to the frameworks that are built from linkers with sizablek_ISCbut. This work opens a new photophysical and photochemical avenue in MOF chemistry and utility in energy conversion schemes.