Himanshu Sekhar Jena

We report, to the best of our knowledge, the first Raman sensor for antibiotics spiked in human plasma using silicon nitride waveguides functionalized with a mesoporous silica top-cladding. Leveraging waveguiding signal enhancement, chemical enrichment, and molecular sieving, we demonstrate detection of 1 mg/l ceftazidime in plasma within 2 min. Ceftazidime quantification is achieved in plasma over 0, 20, 40, and 60 mg/l, demonstrating its potential for clinical use. Requiring minimal sample preparation, this method has great potential for point-of-need monitoring for optimal antibiotic therapy.

25 years after the first papers on the development of Periodic Mesoporous Organosilicas, and in this special issue in honor of prof. Ozin who stood at the cradle of PMOs, we here report for the first time an “acac-PMO” with the acac-functionality intact and embedded in the organic environment of the linker. Periodic mesoporous organosilicas (PMOs) have emerged as versatile sensors due to their stability, low toxicity, and scalability. This study reports for the first time on embedding the acetylacetone (acac) group into the PMO backbone. This integration of acac into the PMO framework opens new applications in both sensing and catalysis. The Eu³⁺ grafted acac-PMOs demonstrate enhanced sensitivity, with a detection limit of 108 nM, and high selectivity in aqueous copper (Cu²⁺) ion sensing. Additionally, these novel PMOs show high catalytic efficiency in Mannich reactions.

Lanthanide-based periodic mesoporous organosilica (LnPMO) hollow spheres with interior lanthanide-doped fluorides for luminescence turn-off sensing of Hg²⁺ with a low detection limit and wide detection range.

Covalent organic frameworks (COFs) are an emerging class of porous organic polymers that have been utilized as scaffolds for anchoring metal active species to act as heterogeneous catalysts. Though several examples of such COFs exist, a thorough experimental and computational analysis on such catalysts is limited. In this work, a series of two-dimensional (2D) imine COFs (TTA-DFB COF (N), TTA-TBD COF (N∧O), and TTA-DFP COF(N∧N)) were synthesized by using suitable building units to obtain three different coordination sites (N, N∧O, and N∧N). These were post-modified with Pd(II) to catalyze the Suzuki-Miyaura coupling reaction. Pd@TTA-DFB COF, where Pd(II) was coordinated to N sites, showed the fastest reactivity and lower stability. Pd@TTA-DFP COF showed highest stability but slowest reactivity. Pd@TTA-TBD COF was the best among the three with both high stability and fast reactivity. By combining both experimental and computational results, we conclude that the Pd(II) to Pd(0) reduction is a key step in the difference between the catalytic reactivities of the three COFs. This study demonstrates the importance of the building block approach to design COFs for efficient heterogeneous catalysis and to understand the fate of the reaction profile.

Iodoarenes are important precursors for fine chemicals and pharmaceuticals. The direct iodination of arenes using molecular iodine (I₂) has emerged as an attractive green synthesis method. Most of the direct iodination protocols are still homogeneous systems that require harsh conditions and use or produce toxic products. We report a new heterogeneous catalytic route for the direct aerobic iodination of arenes under mild conditions using a PMoV₂ polyoxometalate (POM) embedded in the metal-organic framework (MOF) MIL-101 (PMoV₂@MIL-101). The catalyst shows full yield for the conversion of mesitylene to 2-iodomesitylene at a rate that is similar to the homogeneous POM system. Moreover, the catalyst is applicable for a wide range of substrates in an oxygen atmosphere without using any co-catalysts or sacrificial agents. To the best of our knowledge, this is the first report on designing a sustainable and green MOF-based heterogeneous catalytic system for the direct iodination reaction using molecular oxygen and iodine.

Metal–Organic Frameworks (MOFs) can be a good alternative to conventional catalysts because they are non-toxic and can be selective without compromising efficiency. Nano MOFs such as UiO-66 have proven themselves to be competitive in the catalytic family. In this study, we report the excellent catalytic behavior of UiO-66 MOF in the reduction of a model reaction: 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) over MOF-5 (Zn-BDC) and MIL-101 (Fe-BDC). Nano UiO-66 crystals were synthesized by a hydrothermal process and characterized by Powder X-ray Diffraction, Diffused Reflectance UV-Vis spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. The catalysts’ performance during the hydrogenation reduction reaction from 4-NP to 4-AP was investigated in the presence of a reducer, NaBH₄. The UiO-66 nano crystals exhibited excellent catalytic behavior owing to its large surface area and Lewis acidic nature at the metal nodes. Furthermore, UiO-66 showed excellent recyclability behavior, verified during repeated consecutive use in a sequence. The catalyst yielded similar catalytic behavior during the reduction of nitrophenols at each cycle, which is a novel finding.