Insights into developing innovative routes for the stabilization of photogenerated charge-separated states by suppressing charge recombination in photocatalysts is a topic of immense importance. Herein, we report the synthesis of a metal−organic framework (MOF)-based composite where CdS nanoparticles (NPs) are confined inside the nanosized pores of Zr 4+ -based MOF-808, namely, CdS@MOF-808. Anchoring L-cysteine into the nanospace of MOF-808 via postsynthetic ligand exchange allows the capture of Cd 2+ ions from their aqueous solution, which are further utilized for in situ growth of CdS NPs inside the nanosized MOF pores. The formation of CdS@MOF-808 opens up a possibility for visible-light photocatalysis as CdS NPs (1−2 nm) are a well-studied semiconductor system with a band gap of ∼2.6 eV. The confinement of the CdS NPs inside the MOF pores, close to the Zr 4+ cluster, opens up a shorter electron transfer route from CdS to the catalytic Zr 4+ cluster and shows a high rate of H 2 evolution (10.41 mmol g −1 h −1 ) from water with a loading of 3.56 wt % CdS. In contrast, a similar composite in which CdS NPs are stabilized on the external surface of MOF-808 reveals poor activity (0.15 mmol g −1 h −1 ). CdS NPs stabilized on the MOF-808 surface show slower and inefficient electron transfer kinetics compared to CdS stabilized inside the nanospace of the MOF, as realized by the transient absorption measurements. Therefore, this work unveils the critical role of stabilizing the photosensitizer NPs in close proximity of the catalytic sites in MOF systems towards developing highly efficient H 2 evolution photocatalysts.

Metal-organic frameworks (MOFs, also known as porous coordination polymers or PCPs) are a novel class of crystalline porous material. The tailorable porous structure, in terms of size, geometry and function,...

In recent years, extensive research has been directed toward the successful preparation of nanoscale luminescent thermometers with high sensitivities operative in a broad temperature range. To achieve this goal, we have devised a unique design and facile multistep synthesis of Zr-ctpy-NMOF@ Tb x Eu y compounds by confining Ln-complexes (Ln = Eu 3+ /Tb 3+ ) into a robust nanoscale Zr-NMOF (MOF-808) via postsynthetic modification. Covalent grafting of 4-(4′-carboxyphenyl)-2,2′:6,2″terpyridine ligand (ctpy) with a high triplet state energy and corresponding immobilization of bimetallic Ln 3+ ions resulted in yellow light-emitting Zr-ctpy-NMOF@Tb 1.66 Eu 0.14 to achieve a sensitivity of 5.2% K −1 (thermal uncertainty dT < 1 K) operative over a broad temperature range of 25−400 K. To defeat the odds related to the detection of minute temperature changes using luminescent materials, we prepared a white light-emitting Zr-ctpy-NMOF@Tb 1.4 Eu 0.31 that showed temperature-modulated multispectrum chromism where the color drastically changes from green (at 25 K, Q.Y.: 20.21%) to yellowish-green (at 200 K, Q.Y.: 23.13%) to white (at 300 K, Q.Y.: 26.4%) to orange (at 350 K, Q.Y.: 26.93%) and finally red (at 400 K, Q.Y.: 28.2%) with a high energy transfer efficiency of 49.8%, which is further supported by electron−phonon coupling.

Five isostructural 1D porous coordination polymers (PCPs) of TbIII (1), EuIII (2), YbIII (3), NdIII (4) and ErIII (5) have been synthesized using a flexible tripodal organic linker and characterized....

The sensitive and instantaneous detection of a variety of classes of analytes using a single material exemplifies an environmentally and economically lucrative approach. Herein, the presence of an excited-state intramolecular...

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Herein, we have demonstrated a simple nickelcatalyzed C-3-selective alkylation of 2-oxindoles using a wide variety of secondary alkyl alcohols. As a special highlight, functionalization of the cholesterol derivative was reported. Control experiments, initial mechanistic studies, and deuterium-labeling experiments were performed for the alkylation process.

Shaheen Bagh - how an indefinite sit-in became an organic protest site and used art as resistance.