Department of Chemistry

India has an ambitious target of achieving 300 GW of solar power by 2030. Conventional methods for producing solar power involve absorbing sunlight by a molecule and converting it directly into electricity. This is possible only during the daytime when sunlight is available. An interesting and complementary prospect is storing the absorbed solar energy by converting it into a different form of energy, such as chemical energy, which can then be transformed into electrical energy when sunlight is not available during the night-time.

To realise this prospect, Assistant Professor Dr Baswanth Oruganti from the Department of Chemistry has designed a molecule that can absorb solar energy and convert it into the chemical energy of the bonds. His paper titled Modulating the Photocyclization Reactivity of Diarylethenes through Changes in the Excited-State Aromaticity of the π-Linker has been published in the Journal of Organic Chemistry, on Cover Page, with an impact factor of 4.2. He is both the first author as well as the corresponding author of the article. For this project, he has collaborated with Prof Bo Durbeej, Division of Theoretical Chemistry, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Sweden.

Abstract

In recent years, the concept of excited-state aromaticity and its applications in photophysics and photochemistry has attracted considerable research interest. Our study uses quantum chemical calculations to systematically investigate if the photocyclization reactivity of diarylethene switches can be controlled by the excited-state aromaticity of the ethene bridge. Indeed, we demonstrate that these switches can be transformed from being highly reactive to completely non-reactive by changing the excited-state character of the bridge from anti-aromatic to aromatic.

Generally, molecules tend to move from a high-energy state to a low-energy state, as the lowering of energy increases the stability of the molecule and makes it chemically less reactive. In contrast, the present study shows that it is possible to chemically transform a molecule from a low-energy (aromatic) state to a high-energy (non-aromatic) state by absorption of light. This reaction occurs via a high-energy (anti-aromatic) electronically excited state of the molecule induced by light and has potential applications for storing solar energy in the form of chemical energy.

One challenge in the design of molecular solar energy storage systems, such as the diarylbenzene designed in the study, is that it is difficult to store solar energy for a longer period due to the instability of the newly formed chemical bonds at room temperature. To store solar energy for a longer period, one needs to compromise on the amount of energy stored in the bonds. In this regard, in the future, researchers are planning to optimise their molecular design by finding the right balance between the amount of solar energy stored and the time period for which it can be stored.

Material Chemistry is rapidly emerging as a critical component of contemporary science. Due to its interdisciplinary nature, the field requires input from all diverse branches of Chemistry. The Department of Chemistry is organising a Faculty Development Programme on Recent advancements in Materials Chemistry. Renowned academicians Prof Srinivas Hotha, IISER Pune, and Prof Chilla Malla Reddy, IISER Kolkata, will be the programme’s keynote speakers.

Prof Srinivas Hotha will deliver a talk on Discovery and Development of Gold-Catalyzed Glycosylation for the Synthesis of Oligosaccharides, and Prof Chilla Malla Reddy will handle a session on Adaptive Soft Molecular Crystals: From Bending to Self-healing Assistant Professor Dr Nimai Mishra and DST – Ramanujan Fellowship Faculty Dr Satheesh Ellipilli are the convenors of the event.

Date: September 7, 2022

Time: 2 PM to 5 PM

About the speakers

Prof Srinivas Hotha is the Dean of Planning and Communications at IISER Pune. He is an expert faculty in Chemistry and Glycochemical Biology. He has more than 25 years of experience in the field of teaching and research. He completed his PhD at Osmania University, Hyderabad.

Prof Chilla Malla Reddy is from the Department of Chemical Sciences of IISER Kolkata. He did his PhD in Supramolecular Chemistry and Crystal engineering from the University of Hyderabad. He continued his research as a post-doctoral fellow at Karlsruhe Institute of Technology, Germany. He has been awarded the prestigious Swarna Jayanti fellowship by the Department of science and technology, Government of India.

The Ministry of Electronics and Information Technology (MeitY) established the Indian Nanoelectronics User’s Programme (INUP) about a decade ago with the intention of improving skilled manpower in the areas of micro and nanoelectronics. This has laid the necessary foundation for the next step of the programme, INUP-i2i. It is a matter of pride that four PhD students from the Department of Chemistry attended the INUP-i2i Familiarisation Workshop on Nanofabrication and characterisations held from August 10 to 12, 2022, at IIT Kharagpur. Mr Syed Akhil, Mr Rahul SIngh, Mr Manoj Palabathuni, and Mr Subarna Biswas are the scholars who have grabbed this incredible opportunity.

Indian Nanoelectronics User’s Programme- Idea to Innovation (INUP-i2i) is developed to facilitate and support the generation of expertise in Nanoelectronics through participation and utilisation of the facilities at Nano-centres at IISc Bangalore, IIT Bombay, IIT Delhi, IIT Kharagpur, IIT Madras, and IIT Guwahati.

INUP will provide easy access to state-of-the-art nanofabrication and characterisation facilities to researchers, thereby creating a critical mass of hands-on experimental researchers across the country. This workshop is being organised both for familiarisation and interaction of the participants with faculty members of IITKGP. INUP has provided the accommodation and food for these shortlisted students. At the end of the workshop, they presented a poster as well.

The Department of Chemistry is glad to announce that Assistant Professor Dr Nimai Mishra and his research group Manoj Palabathuni, Syed Akhil, and Rahul Singh have published an article titled “Charge Transfer in Photoexcited Cesium Lead Halide Perovskite Nanocrystals: Review of Materials and Applications” in the Q1 journal “ACS Applied Nano Materials ” published by The American Chemical Society. The journal has an Impact Factor of 6.14.

Cesium Lead Halide (CsPbX3) perovskite nanocrystals (PNCs) have attracted significant views from researchers due to their essential optoelectronic properties, especially long charge carrier transfer, high efficiency in visible light absorption, and long excited states lifetime, etc. Because of these properties, these materials exhibit outstanding charge transfer and charge separation, which enables them for solar cell applications. Recently, cesium lead halide perovskites have emerged as photocatalysts. In photovoltaics or photocatalysis, upon photoexcitation, the exciton dissociates, and the electron/hole is transmitted from the conduction/valance bands to the electron/hole acceptors. Therefore, it is essential to understand how the charge transfer occurs at the PNCs interface, which can help the researcher maximize the output in solar cells and photocatalytic efficiency.

In this article, Dr Mishra’s research group has outlined different charge transfer dynamics based on critical factors and discussed their optoelectronic properties. Electron/hole transfer dynamics are the most concerning characteristic; thus, they reviewed the relevant literature that reported efficient electron/hole transfer performance. In the end, they highlighted the recent development of the use of perovskite nanocrystal as photocatalyst in organic synthesis.

Read the full paper here