Research Area

Inorganic and Organometallic Chemistry

• Transition metal carbene and isocyanide complexes
• Abundant luminescent complexes
• Photochemistry and spectroscopy
• Catalyst design and photocatalysis

Research Interests

We will be working on cutting-edge research topics in the field of Inorganic and Organometallic Chemistry. One of our core research topics is to develop abundant transition metal based photocatalysts and their application in photocatalysis. Most of the well-known transition metal based photocatalysts are made from rare and expensive 4d6 or 5d6 metals like Ru(II), Os(II), Ir(III). These are extensively used in various fields of photochemistry, for example, photocatalysis, light-emitting diodes (LEDs), solar energy conversion, bioimaging, photodynamic therapy and so on, due to the presence of long-lived and highly emissive metal-to-ligand charge transfer (MLCT) excited states. Our focus is to replace these expensive luminophores with abundant and isoelectronic first-row transition metals like Cr(0), Mn(I), Fe(II) and Co(III).

Our major goal is to design innovative ligands based on N-heterocyclic carbenes (NHCs) and arylisocyanides. Then these ligands will be incorporated with first-row transition metals, to prepare new organometallic complexes in the direction that these complexes will be photoactive as mentioned in the previous section. After successful preparation of these complexes, they will be characterized by various analytical methods including NMR spectroscopy, mass spectrometry, IR spectroscopy, and X-ray crystallography. If the complexes are photoactive then additional characterizations like UV-Vis and luminescence spectroscopy, transient absorption spectroscopy, cyclic voltammetry, spectro-electrochemistry will be carried out. Thereafter, these complexes will be used in light induced energy and electron transfer catalysis, and other various applications of photochemistry.

Representative Publications

• N. Sinha, P. Yaltseva, O. S. Wenger,* “The Nephelauxetic Effect Becomes an Important Design Factor for Photoactive First-Row Transition Metal Complexes,” Angew. Chem. Int. Ed. 2023, 62, e202303864.
• N. Sinha, O. S. Wenger,* “Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d6 Complexes with Cr(0), Mn(I), Fe(II), and Co(III),” J. Am. Chem. Soc. 2023, 145, 4903-24920.
• N. Sinha, B. Pfund, C. Wegeberg, A. Prescimone, O. S. Wenger,* “Cobalt(III) Carbene Complex with an Excited-State Structure Similar to Cyclometalated Iridium(III) Compounds,” J. Am. Chem. Soc. 2022, 144, 9859-9873.
• N. Sinha, J.-R. Jiménez, B. Pfund, A. Prescimone, C. Piguet,* O. S. Wenger,* “A Near-Infrared-II Emissive Chromium(III) Complex,” Angew. Chem. Int. Ed. 2021, 60, 23722-23728.
• N. Sinha, L. Stegemann, T. T. Y. Tan, C. A. Strassert,* F. E. Hahn,* “Turn on Fluorescence in Tetra-NHC Ligands by Rigidification through Metal Complexation: An Alternative to Aggregation-Induced Emission,” Angew. Chem. Int. Ed. 2017, 56, 2785-2789.

Recent Publications

• N. Sinha, C. Wegeberg, D. Häussinger, A. Prescimone, O. S. Wenger,* “Replacing Noble Ru(II) and Os(II) with Abundant Cr(0) in Photoactive Complexes,” Nat. Chem. 2023 (accepted).
• B. Mondal, R. Naskar, A. Dey, N. Sinha, F. E. Hahn,* R. Maity,* “Trinuclear Pd(II) Complexes Bearing a C3-Symmetric Triphenylbenzene-Based Tris-NHC Ligand: Catalytic Benefits,” Chem. Eur. J. 2023, 29, e202300548.
• H. Li, C. Wang, F. Glaser, N. Sinha, O. S. Wenger,* “Metal-Organic Bichromophore Lowers the Upconversion Excitation Power Threshold and Promotes UV Photoreactions,” J. Am. Chem. Soc. 2023, 145, 11402–11414.
• T. Ogawa, N. Sinha, B. Pfund, A. Prescimone, O. S. Wenger,* “Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes,” J. Am. Chem. Soc. 2022, 144, 21948-21960.
• N. Sinha, D. Heijnen, B. L. Feringa,* M. G. Organ,* “Murahashi Cross-Coupling at -78 °C: A One-Pot Procedure for Sequential C-C/C-C, C-C/C-N, and C-C/C-S Cross-Coupling of Bromo-Chloro-Arenes,” Chem. Eur. J. 2019, 25, 9180–9184.