Research
Key Research Topics
Theoretical Spectroscopy
Water Dynamics at Surfaces & Interfaces
Desalination of Sea-Water
Nano Confinement and Water Dynamics
Metalloproteins: Structure, Dynamics and Biological Activities
Chemical Dynamics in Condensed Phases
Theoretical Spectroscopy
The bulk water hydrogen bond network gets significantly modified in presence of external solutes. The presence of external solutes perturbs the length scale and the time scale of the hydrogen bond network that makes the systems even more interesting. As the vibrational frequencies of water are highly sensitive to the local microscopic solvation structure, ultrafast IR spectroscopy is an appealing method for investigation of these systems. In spite of its extensive use, meaningful interpretation of IR spectroscopy faces the formidable challenge of establishing the connection among the experimental spectra to molecular structures in the bulk phase. Experimental spectra show a superposition of different transient solvation structures, hence represent the macroscopic response. Moreover, the presence of strong anharmonic couplings leads to further delocalization through mixing the character of different vibrational modes. On the contrary, the microscopic resolution of computer simulation assisted spectroscopy modelling enables us to study these systems at the molecular level. We use several theoretical spectroscopy methodologies to decipher the experimental data in rather quantitative way.
Publications:
Why does urea not alter the vibrational spectroscopic signatures of water? P. Adhikary and R. Biswas, Chemical Physics Impact 8,100609 (2024).
Theoretical Spectroscopy Aided Validation of Hydration Structure of Trimethylamine N-oxide (TMAO), K. D. Reddy and R. Biswas, J. Phys. Chem. B (part of the virtual special issue "Early-Career and Emerging Researchers in Physical Chemistry Volume 2”) 127, 12, 2774–2783 (2023).
Effects of hydrophobic solute on water normal modes, K. D. Reddy, A. Joy and R. Biswas, Chem. Phys. 550, 111303 (2021) (arxiv:2105.00640).
Theoretical Spectroscopy of Isotopically Dilute Water and Hydrophobicity, K. D. Reddy and R. Biswas, J. Chem. Phys. 153, 094501 (2020) (arXiv:2006.07960v1).
IR spectral assignments for the hydrated excess proton in liquid water, R. Biswas, W. Carpenter, J. A. Fournier, G. A. Voth and A. Tokmakoff, J Chem Phys 146, 154507 (2017).
Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water, R. Biswas, W. Carpenter, G. A. Voth and A. Tokmakoff, J Chem Phys 145, 154504 (2016).
Layer-wise decomposition of water dynamics in reverse micelles: A simulation study of two-dimensional infrared spectrum, R. Biswas and B. Bagchi, J. Chem. Phys. 139, 144906, (2013).
Funding:
"Theoretical spectroscopic investigation of the microscopic origin of chaotropicity and kosmotropicity of osmolytes," SERB-DST, 2021-2024.
Water Dynamics at Surfaces & Interfaces
The continuous evolution of hydrogen bond network makes water as one of the most interesting liquid. In spite of the restriction of its smaller size, water molecules are capable of behaving hydrogen bond donor and acceptor simultaneously. As a result a massive hydrogen bond network is abundant in bulk water. The ultrafast evolution of this gigantic hydrogen bond network gives rise to many unique properties of water. A huge number of experimental and theoretical investigations have been and are still being dedicated to understanding the source of the anomalous properties of water. Still, many characteristics of its dynamical features remain ill understood.
In nature, water is frequently found in contact with a variety of surfaces of different length scales. This includes lipid bilayers, reverse micelles, biomolecules like proteins, DNA etc. While the presence of surfaces and interfaces disrupts the uninterrupted hydrogen bond network of liquid water, confinement on a mesoscopic scale originates novel features. We investigate the rich dynamics of water in presence of different exotic surfaces and interfaces by computer simulations and phenomenological modelling approach.
Anomalous water dynamics at surfaces and interfaces: Synergistic effects of confinement and surface interactions, R. Biswas and B. Bagchi J. Phys. Cond. Mat. 30, 013001 (2017).
Non-monotonic, distance-dependent relaxation of water in reverse micelles: Propagation of surface induced frustration along hydrogen bond networks, R. Biswas, T. Chakraborti, B. Bagchi and K. G. Ayappa, J. Chem. Phys. 137, 014515 (2012).
A kinetic Ising model study of dynamical correlations in confined fluids: Emergence of both fast and slow time scales, R. Biswas and B. Bagchi, J. Chem. Phys. 133, 084509 (2010).
Metalloproteins: Structure, Dynamics and Biological Activities
A class of proteins that comprise metal ions as cofactors are commonly known as metalloproteins. Nearly half of all proteins in biology are metalloproteins. Metalloproteins possess exceptionally critical role in nature. They are responsible for catalyzing some of the most fundamental functions, which includes photosynthesis, respiration, water oxidation, molecular oxygen reduction, and nitrogen fixation etc. After the landmark discovery of iron in sperm whale myoglobin by X-ray crystal structure during 1950s, scientists took significant interests in exploring the metalloproteins. Metalloproteins play critical responsibilities in many biological activities, and their malfunctioning or anomalous over-expression has been related to a variety of diseases. We use advanced state of the art computational methodologies to study structure, dynamics and function of these special class of bio-macromolecules.
Significance of Disulfide Bridge in the Structure and Stability of Metalloprotein Azurin, A. Joy and R. Biswas, J. Phys. Chem. B 128, 4, 973–984 (2024).
Role of Metal Cofactor in Enhanced Thermal Stability of Azurin, A. Joy and R. Biswas, J. Phys. Chem. B 127, 4374–4385 (2023).
Molecular Insight into the High Thermal Stability of Metalloprotein Azurin, A. Joy and R. Biswas, J. Phys. Chem. B (Kankan Bhattacharyya Festschrift), 126, 2496–2506 (2022).
Desalination of Sea-Water
Drinking water scarcity is a significant problem and is increasing with the urbanization of society. Desalination only accounts for a fraction of the world’s potable water supply, and groundwater remains the primary source of drinking water even today. The membranes-based reverse osmosis (RO) is the leading process in this area. The alternate membrane desalination technology is growing and has the potential to become the most efficient technique for long-term water sustainability across the globe. Using computational modellings and molecular simulations, we aim to explore water desalination using biologically motivated artificial water channels.
Funding:
“Theoretical Investigation of Bio-inspired Channel Based Membrane for Water Purification,” SERB-DST, 2022-2025.