Department of Chemistry

SRM University-AP is pleased to announce that Dr Nimai Mishra, Assistant Professor, Department of Chemistry, SRM University-AP, Andhra Pradesh, along with his research group comprising of students pursuing PhD under him, Mr Rahul Singh, Mr Syed Akhil, and Ms V.G.Vasavi Dutt, has published a research article titled “Shell thickness-dependent photostability studies of green-emitting “Giant” quantum dots” in the journal Nanoscale Advances (The Royal Society of Chemistry) with an impact factor of ~4.533.

About the research:

Highly efficient green-emitting core/shell giant quantum dots have been synthesized through a facile “one-pot” gradient alloy approach. Furthermore, an additional ZnS shell was grown using the “Successive Ionic Layer Adsorption and Reaction” (SILAR) method. Due to the faster reactivity of Cd and Se compared to an analogue of Zn and S precursors it is presumed that CdSe nuclei are initially formed as core and gradient alloy shells simultaneously encapsulate the core in an energy-gradient manner and eventually thick ZnS shells were formed. Using this gradient alloy approach, we have synthesized four different sized green-emitting giant core-shell quantum dots to study their shell thickness-dependent photostability under continuous UV irradiation, and temperature-dependent PL properties of nanocrystals. There was a minimum effect of the UV light exposure on the photostability after a certain thickness of the shell. The QDs diameter of ≥ 8.5 nm shows substantial improvement in photostability compared to QDs with a diameter ≤ 7.12 nm when continuously irradiated under the strong UV light (8 W/cm2, 365 nm) for 48 h. The effect of temperature on the photoluminescence intensities was studied with respect to shell thickness. There were no apparent changes in PL intensities observed for the QDs ≥ 8.5 nm, on the contrary, for example, QDs with < 8.5 nm in diameter (for ~7.12 nm) show a decrease in PL intensity at higher temperatures ̴90°C.

More importantly, these results highlight the synthesized green-emitting gradient alloy QDs with superior optical properties can be used for highly efficient green emitters and are potentially applicable for the fabrication of green LEDs.

Read the full paper: https://pubs.rsc.org/en/content/articlelanding/2021/NA/D1NA00663K

SRM University-AP could not be more proud to announce that Dr S Mannathan, Head of Department of Chemistry has made it to the top 5% in the list of the Most Cited Authors by the Royal Society of Chemistry. It is inspiring to have a faculty member in our midst whose work has helped and facilitated the research of so many others.

Dr Mannathan obtained his doctorate from National Tsing Hua University, Taiwan. His research interests primarily lie in Metal-catalyzed organic transformation reactions, Multicomponent reactions, and Asymmetric synthesis. His research followed by scientists all over the world leading him to become one of the top 5% authors in terms of citations

In the field of Transition Metal Complexes as Catalysts in Organic Reactions, he particularly leans towards ‘Nickel-and cobalt-catalyzed three-component coupling and reductive coupling reactions’, and ‘Palladium-catalyzed reductive arylation’. Similarly, in Asymmetric Synthesis, he favours research into ‘Asymmetric reductive Heck reaction for the synthesis of chiral indanones’, and ‘Synthesis of bicyclic tertiary alcohols and its related asymmetric version via reductive [3+2] cycloaddition reaction by using chiral cobalt complexes.’

About the top 5% most cited paper:

In this work, he reported the synthesis and application of a Zn-Bp-BTC MOF (Bp – 4,4′-bipyridine; BTC – 1,3,5-benzene tricarboxylic acid; MOF – metal organic framework) as a heterogeneous catalyst for mediating organic reactions. Initial reaction conditions were optimized for the Knoevenagel condensation reaction using Zn-Bp-BTC as a heterogeneous catalyst. Various factors such as the effect of solvent, temperature and catalyst loading were evaluated. Although the reaction proceeded at room temperature using methanol as the solvent, 60 °C offered the best yield in a shorter duration. Under optimized reaction conditions, a wide range of α,β-unsaturated dicyano compounds were prepared from the corresponding carbonyl precursor and malononitrile, the active methylene counterpart. A systematic investigation was also carried out to assess the role of the ligand and metal salt in the Knoevenagel condensation reaction. It was found that the Zn-Bp-BTC MOF catalyzed the reaction efficiently in comparison to its analogue Zn-BTC MOF and precursor Zn(NO 3 ) 2 ·6H 2 O. Finally, catalytic recycling and stability studies showed that the catalyst is able to mediate the reaction for up to five consecutive cycles without undergoing any significant chemical or morphological changes. Further, the catalyst was tested for its efficacy in a multicomponent reaction (MCR). An MCR with the Zn-Bp-BTC MOF as the catalyst afforded good yields and there was no reaction in the absence of the catalyst. Similarly, the catalyst was tested for its efficiency in benzimidazole synthesis.

Dr Mannathan did this research in collaboration with Dr. Kathiresan Murugavel, Scientist, Electro Organic Division, CSIR-Central Electrochemical Research Institute (Govt of India), Karaikudi.

SRM University-AP is honoured to host Dr Satheesh Ellipilli as a DST- Ramanujan Fellowship Faculty and facilitate his research for the next five years.

Ramanujan Fellowship is one of the most prestigious scientific fellowships that is offered to the Indian scientists working abroad. This fellowship is offered by Science and Engineering Research Board (SERB) to encourage scientists of Indian origin to return and research in an Indian institute/University.

SERB offers the scientists Rs 1,35,000/- per month along with research grant of Rs 7,00,000/- per annum and Rs 60,000/- per annum for overhead charges.

Dr. Satheesh Ellipilli obtained his PhD from Indian Institute of Science Education and Research, Pune. He worked as a postdoctoral researcher in The Ohio State University (Columbus, USA), Emory University (Atlanta, USA), and The University of Utah (Salt Lake City, USA).

Dr. Satheesh Ellipilli has extensive experience in the field of nucleic acid chemistry, particularly, focusing on utilization of RNA nanotechnology for cancer therapy using RNAi therapeutics in combination with small molecule drugs.

He has made numerous publications in some of the most renowned journals like Journal of Organic Chemistry, Journal of Controlled Release, Chemical Communications, Bioconjugate Chemistry, Organic and Biomolecular Chemistry, and Chemical Review to name a few.

Having Dr Ellipilli with us for the duration of his fellowship is a golden learning opportunity and a pleasure to be the host institution for his work. We hope that our students and scholars develop stronger research ethics and acumen in his company.

Dr Nimai Mishra, Assistant Professor, Department of Chemistry, SRM University-AP along with his team comprising of his PhD scholars Mr. Syed Akhil, Ms. V.G.Vasavi Dutt, and Mr Rahul Singh have published a research article titled “Surface-State-Mediated Interfacial Hole Transfer Dynamics Between CsPbBr3 Perovskite Nanocrystals and Phenothiazine Redox Couple” in The Journal of Physical Chemistry-C, published by The American Chemical Society with an impact factor of ~4.126.

Dr Mishra’s research interests lie in Semiconductor nanocrystals, Core/shell branched structures, Nanowires, Perovskite nanocrystals and Optoelectronic device fabrication. He studied the role of surface chemistry for improving excited state hole transfer from CsPbBr3 nanocrystals to an acceptor, potentially applicable for photocatalytic applications.

About the research:

Recently, caesium lead bromide (CsPbBr3) perovskite nanocrystals (PNCs) gained enormous attention for designing photocatalytic reactions because of their photocatalytic properties. But the surface chemistry of nanocrystals is often ignored which dictate the excited state interactions of these semiconductor nanocrystals with the charge shuttling redox-active molecules. In this work, we have explored the impact of CsPbBr3 perovskite nanocrystals with the three different surface chemistries on the excited state interactions with the standard hole acceptor phenothiazine molecule. From the steady PL-lifetime decay measurements we have calculated the photoinduced hole transfer (PHT). In the amine-free PNCs case, PHT is 6 times higher than the conventional amine capped ligands. Using the lifetime fast component (1) rate constants, we have calculated the hole transfer constant (kht) which is 3.942 × 108 s-1 and it is 4 times higher in amine-free ligands when compared with conventional amine ligands system.

According to Dr Nimai Mishra, the most important contribution of this research is that these results highlight the impact of surface chemistry on the excited state interactions of CsPbBr3 PNCs and conclude amine-free PNCs could be an ideal candidate for photocatalytic reactions.

Read the full paper: https://pubs.acs.org/doi/10.1021/acs.jpcc.1c07129