Partha P. Kundu

Bio: Partha P. Kundu is an academic researcher from Jawaharlal Nehru Centre for Advanced Scientific Research. The author has contributed to research in topics: Catalysis & Raman spectroscopy. The author has an hindex of 6, co-authored 13 publications receiving 93 citations.

Dielectric and Raman investigations of structural phase transitions in (C2H5NH3)2CdCl4

Abstract: Temperature-dependent Raman and dielectric measurements have been carried out on (C2H5NH3)2CdCl4 single crystals. Raman studies reveal the presence of two structural phase transitions below room temperature at 216 K and 114 K. The phase transitions are marked by anomalies in temperature dependence of wave-number and full width half maximum (FWHM) of several vibrational modes. The transitions are also accompanied by anomalies in dielectric measurements. Raman and dielectric data indicate that the transition at 216 K is order–disorder in nature and is driven by re-orientation of organic ions, while the transition at 114 K is due to coupling between the CdCl6 octahedron and the organic chain. Further high temperature dielectric measurements reveal the presence of one more structural phase transition around 473 K across which dispersion in dielectric parameters is observed. The activation energies and relaxation time obtained for high temperature dielectric phases are characteristic of combined reorientation motions of alkyl ammonium cations.

Surface enhanced Raman spectroscopy of Aurora kinases: direct, ultrasensitive detection of autophosphorylation

Abstract: Highly sensitive surface enhanced Raman spectroscopy (SERS) was used to study two of the tumorigenic aurora family kinases, Aurora A and Aurora B in sub-picomole quantities. Significantly, the proteins on conjugating to SERS-active citrate-capped silver nanoparticles retain their enzyme activity as demonstrated by kinase assays, making SERS suitable for studies of enzymatic processes. The ability to differentiate between two structurally similar homologous proteins further corroborates the sensitivity of this technique. Based on the available structural information we demonstrate here that SERS could be used for direct and ultra-sensitive detection of autophosphorylation. The overall reduction in SERS intensity and the presence of bands at 952 and ∼1076 cm−1 confirmed the phosphorylated state of Aurora A. Thus, the detection of autophosphorylation in a full length protein is demonstrated for the first time using SERS, which is critical to attain its active conformation.

Novel Heterogeneous SO3Na-Carbon Transesterification Catalyst for the Production of Biodiesel

Abstract: Glycerol, a major biodiesel by-product, was valorised into a novel and highly stable heterogeneous carbon-based solid base catalyst with transesterification activity. The SO3H-carbon catalyst developed previously by us from glycerol was modified into base catalyst by treating with aqueous alkali under controlled conditions. The reported solid base catalyst is first of its kind having polycyclic aromatic carbon sheets attached with -SO3Na, -COONa and -ONa functionalities. The catalyst was characterized for its structural properties using XRD, FTIR, 13C-MAS NMR, XPS, EDAX, SEM, TEM, TG/DTA, ICP-OES and Raman spectral techniques. The SO3Na- catalyst was employed for the transesterification of sunflower oil to fatty acid methyl esters (biodiesel) in high yields (99%) at atmospheric pressure. The strong basic sites of the catalyst contributed to its remarkable performance and the activity was intact even after 8 cycles of reuse without any leaching, indicating its high structural stability. Thus, the reported SO3Na-carbon catalyst possessed the potential of green and economic biodiesel production from oils & fats apart from clean glycerol as by-product.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Functionalised heterogeneous catalysts for sustainable biomass valorisation

Abstract: Efficient transformation of biomass to value-added chemicals and high-energy density fuels is pivotal for a more sustainable economy and carbon-neutral society. In this framework, developing potential cascade chemical processes using functionalised heterogeneous catalysts is essential because of their versatile roles towards viable biomass valorisation. Advances in materials science and catalysis have provided several innovative strategies for the design of new appealing catalytic materials with well-defined structures and special characteristics. Promising catalytic materials that have paved the way for exciting scientific breakthroughs in biomass upgrading are carbon materials, metal–organic frameworks, solid phase ionic liquids, and magnetic iron oxides. These fascinating catalysts offer unique possibilities to accommodate adequate amounts of acid–base and redox functional species, hence enabling various biomass conversion reactions in a one-pot way. This review therefore aims to provide a comprehensive account of the most significant advances in the development of functionalised heterogeneous catalysts for efficient biomass upgrading. In addition, this review highlights important progress ensued in tailoring the immobilisation of desirable functional groups on particular sites of the above-listed materials, while critically discussing the role of consequent properties on cascade reactions as well as on other vital processes within the bio-refinery. Current challenges and future opportunities towards a rational design of novel functionalised heterogeneous catalysts for sustainable biomass valorisation are also emphasized.

Graphene nanomaterials as biocompatible and conductive scaffolds for stem cells: impact for tissue engineering and regenerative medicine

Abstract: The discovery of the interesting intrinsic properties of graphene, a two-dimensional nanomaterial, has boosted further research and development for various types of applications from electronics to biomedicine. During the last decade, graphene and several graphene-derived materials, such as graphene oxide, carbon nanotubes, activated charcoal composite, fluorinated graphenes and three-dimensional graphene foams, have been extensively explored as components of biosensors or theranostics, or to remotely control cell-substrate interfaces, because of their remarkable electro-conductivity. To date, despite the intensive progress in human stem cell research, only a few attempts to use carbon nanotechnology in the stem cell field have been reported. Interestingly, most of the recent in vitro studies indicate that graphene-based nanomaterials (i.e. mainly graphene, graphene oxide and carbon nanotubes) promote stem cell adhesion, growth, expansion and differentiation. Although cell viability in vitro is not affected, their potential nanocytoxicity (i.e. nanocompatibility and consequences of uncontrolled nanobiodegradability) in a clinical setting using humans remains unknown. Therefore, rigorous internationally standardized clinical studies in humans that would aim to assess their nanotoxicology are requested. In this paper we report and discuss the recent and pertinent findings about graphene and derivatives as valuable nanomaterials for stem cell research (i.e. culture, maintenance and differentiation) and tissue engineering, as well as for regenerative, translational and personalized medicine (e.g. bone reconstruction, neural regeneration). Also, from scarce nanotoxicological data, we also highlight the importance of functionalizing graphene-based nanomaterials to minimize the cytotoxic effects, as well as other critical safety parameters that remain important to take into consideration when developing nanobionanomaterials.

Electron‐State Confinement of Polysulfides for Highly Stable Sodium–Sulfur Batteries

Abstract: Confinement of polysulfides in sulfur cathodes is pivotal for eliminating the "shuttle effect" in metal-sulfur batteries, which represent promising solutions for large-scale and sustainable energy storage. However, mechanistic exploration and in-depth understanding for the confinement of polysulfides remain limited. Consequently, it is a critical challenge to achieve highly stable metal-sulfur batteries. Here, based on a 2D metal-organic framework (2D MOF), a new mechanism to realize effective confinement of polysulfides is proposed. A combination of in situ synchrotron X-ray diffraction, electrochemical measurements, and theoretical computations reveal that the dynamic electron states of the Ni centers in the 2D MOF enable the interaction between polysulfides and the MOF in the discharge/charge process to be tuned, resulting in both strong adsorption and fast conversion kinetics of polysulfides. The resultant room-temperature sodium-sulfur batteries are amongst the most stable reported so far, thus demonstrating that the new mechanism opens a promising avenue for the development of high-performance metal-sulfur batteries.

SERS Quantification and Characterization of Proteins and Other Biomolecules.

Abstract: Changes in protein expression levels and protein structure may indicate genomic mutations and may be related to some diseases. Therefore, the precise quantification and characterization of proteins can be used for disease diagnosis. Compared with several other alternative methods, surface-enhanced Raman scattering (SERS) spectroscopy is regarded as an excellent choice for the quantification and structural characterization of proteins. Herein, we review the main advance of using plasmonic nanostructures as SERS sensing platform for this purpose. Three design approaches, including direct SERS, indirect SERS, and SERS-encoded nanoparticles, are discussed in the direction of developing new precise approaches of quantification and characterization of proteins. While this Review is focused on proteins, in order to highlight concepts of SERS-based sensors also detection of other biomolecules will be discussed.