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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. 

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 Traditional MOF e‐CRR, constructed from catalytic linkers, manifest a kinetic bottleneck during their multi‐electron activation. Decoupling catalysis and charge transport can address such issues. Here, we build two MOF/e‐CRR systems, CoPc@NU‐1000 and TPP(Co)@NU‐1000, by installing cobalt metalated phthalocyanine and tetraphenylporphyrin electrocatalysts within the redox active NU‐1000 MOF. For CoPc@NU‐1000, the e‐CRR responsive Co^I/0potential is close to that of NU‐1000 reduction compared to the TPP(Co)@NU‐1000. Efficient charge delivery, defined by a higher diffusion (D_hop=4.1×10⁻¹² cm² s⁻¹) and low charge‐transport resistance (=59.5 Ω) in CoPC@NU‐1000 led FE_CO=80 %. In contrast, TPP(Co)@NU‐1000 fared a poor FE_CO=24 % (D_hop=1.4×10⁻¹² cm² s⁻¹and=91.4 Ω). For such a decoupling strategy, careful choice of the host framework is critical in pairing up with the underlying electrochemical properties of the catalysts to facilitate the charge delivery for its activation. 

Abstract Charge‐transfer excited state (CTES) defines the ability to split photon energy into work producing redox equivalents suitable for photocatalysis. Here, we report inter‐net CTES formation within a two‐fold catenated crystalline metal–organic framework (MOF), constructed with two linkers, N,N′‐di(4‐pyridyl)‐1,4,5,8‐naphthalenetetracarboxydiimide (DPNDI) and 2,6‐dicarboxynaphthalene (NDC). The structural flexibility puts two complementary linkers from two nets in a proximal position to interact strongly. Supported by the electrochemical and steady‐state electronic spectroscopic data, this ground‐state interaction facilitates forming CTES that can be populated by direct excitation. We map the dynamics of the CTES which persists over a few nanoseconds and highlight the utilities of such relatively long‐lived CTES as enhanced conductivity of the MOF under light over that measured in dark and as a proof‐of‐the‐principle test, photo‐reduction of methyl viologen under white light. 

Abstract Metal‒organic frameworks (MOFs) are widely studied molecular assemblies that have demonstrated promise for a range of potential applications. Given the unique and well-established photophysical and electrochemical properties of porphyrins, porphyrin-based MOFs are emerging as promising candidates for energy harvesting and conversion applications. Here we discuss the physical properties of porphyrin-based MOFs, highlighting the evolution of various optical and electronic features as a function of their modular framework structures and compositional variations.