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Poster Session 2
Poster Session 2
Balasaheb Ghotekar
Balasaheb Ghotekar
Total Synthesis of Lipoteichoic acid of Streptococcus pneumoniae and Streptococcus oralis Uo5
Streptococcus pneumonia and Streptococcus oralis Uo5 are amongst the common gram positive bacteria observed in upper respiratory track where they cause sever infections.2 The cell wall of S. Pneumoniae consists of several layers of peptidoglycans, covalently linked to teichoic acid and of lipoteichoic acid (LTA) that is anchored in the cell membrane. S. oralis Uo5 LTA has an overall architecture similar to pneumococcal LTA (pnLTA). S. pneumoniae is frequently associated with diseases such as otitis media, pneumonia, meningitis. S. mitis and causes disease such as endocarditis.3 When it gains access to the lower respiratory tract or the bloodstream, high mortality rates are often observed. We synthesized both biologically active trisaccharides through a common disaccharide approach. The monosaccharide building blocks were synthesized using our efficient methodology via regioselective displacement of corresponding triflates on D-sugars.
Pankaj Hande
Pankaj Hande
Lewis acid mediated synthesis of highly fluorescent carbazoles via intermolecular [4+2] cycloaddition reaction of the vinylogous carbamates of the carbazoles
Small molecule-fluorophores are being used to visualize the biological events and thus attracted attention in recent years because of its high sensitivity, quick response time and easy preparation.1, 2 Recently, our group has developed a one-step protocol to design small molecule quinoline based ratiometric probe to target the intracellular lysosomal pH.3 Further, to design simplest method to get fluorophore in shortest route, we report TMSOTf mediated intermolecular [4+2] cycloaddition reaction of vinylogous carbamates to get highly fluorescent carbazoles in one step. The carbazoles possess excellent photophysical properties with high quantum yield. Similarly, an attempt has been made to design the ratiometric probe as an out of table example.
Valay Agarawal
Valay Agarawal
Coupled Cluster Theory in Reduced Dimension: Interplay of Nonlinear Dynamics and Shallow Machine Learning
The time series dynamics associated with the iteration scheme of coupled cluster theory has been analysed. The phase space analysis indicates the presence of a few cluster amplitudes, mostly involving valence excitations, which dictate the dynamics, while all other amplitudes are enslaved. The enslaved variables are expressed in terms of those few master amplitudes which behave as the order parameters. A supervised machine learning scheme with polynomial Kernel Ridge Regression method has been employed to express the enslaved variables in terms of the master amplitudes via a few coupled cluster iterations. The subsequent coupled cluster iterations are restricted to a much smaller dimension spanned solely by the order parameters. We will show that our scheme leads to tremendous reduction in computational time without sacrificing the accuracy
Dr. Rajesh Manne
Dr. Rajesh Manne
Tuning of Hydrolytic Stability of Titanium(IV) Complexes by ONO Donor ligands and Correlation of their Cytotoxic Activities
A series of homoleptic Ti(IV) compounds, of the type [Ti(Ln)2] where Ln is a variously substituted dianionic tridentate Schiff base ligands, were synthesized by reacting the appropriate hydrazide or aminoacids with 2-hydroxybenzaldehyde or 2’-hydroxyacetophenone and titanium(IV) tetra(isopropoxide) in a 2:2:1 molar ratio. The solid-state structures of 14 complexes were deduced from the single crystal X-ray diffraction data, which indicated that each L2− ligand is fully deprotonated and coordinated to the Ti(IV) cation via the enolic oxygen, the imino nitrogen and the phenolic oxygen atoms (ONO donor set) in an enol tautomeric form, the metal assuming the distorted octahedral geometry. All complexes displayed high hydrolytic stability. In vitro cytotoxicity assays towards human ovarian A2780 and colon HT-29 cancer cell lines revealed the activity dependence on the hydrolytic stability and the solubility and promoting cytotoxicity. The lead compound of this study presents IC50 values of 2.5 ± 0.2 and 4.2 ± 0.6 µM for ovarian A2780 and colon HT-29 human cancer cells, respectively.
Sanjog Nagarkar
Sanjog Nagarkar
Coordination Polymer Crystals, Glasses and Liquids
Solid to liquid phase transition is a fundamentally important and technologically relevant process. On heating, the cohesive forces operating in the solids “loosen” at a certain temperature (Tm) resulting in the melting of the solid (eg. small molecules, macromolecules, metals, salts). The phenomenon offers opportunities to synthesize new functional solid (eg. Glasses, composites, glass-ceramics) and liquid (porous liquids) materials having unique properties and functions. This is in addition to beneficial processability and formability to synthesize large single-crystals, films, fibers impregnations, etc. Surprisingly, this important phenomenon remained unexplored in the realm of inorganic-organic hybrid materials. Coordination polymers (CPs) constitute an important class of hybrid material, wherein metal ions and ligands are periodically connected to form a highly ordered crystalline network structure. While tens of thousands of CPs have been reported, on heating, most of the CPs decompose without melting, except for a handful of CPs. In our group, we are interested in developing CP based new hybrid glasses and liquids for emerging applications. Here, we present design strategies we have explored to make CP glasses and their applications in clean energy research.
Arnab
Arnab
Decoding nature’s blueprint for solar to chemical energy transformation
Renewable energy resources (such as solar, wind, or tidal) have emerged as the most promising options for replacing the existing fossil fuel economy. However, the intermittent nature and dilute energy density of these alternative energy resources have restricted their practical application. Our lab is interested in following a natural photosynthesis-inspired strategy where renewable energy resources can be stored in readily usable chemical feedstocks. Here, we are originating photo-driven small molecule activation reactions such as hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and water oxidation reaction (WOR) to facilitate solar to chemical energy conversion. In this pursuit, we have developed earth-abundant first-row transition metal-based molecular catalysts containing natural metalloenzymes' hallmarks. We have followed their activity via a series of electrochemical and photocatalytic in aqueous solution.
Harish
Harish
Pd(II) and Pt(II) Assisted Tandem P−C Bond Breaking and P−N Bond Formation Reactions by an Amide Functionalized Bisphosphine: Synthesis, Mechanistic Studies and Catalytic N-alkylation Reactions
Metathesis1 is one of the important reactions in organic chemistry owing to its applications in the field of drug discovery, in biomass valorisation including alkene metathesis.2 In particular, metathesis of C(sp2)–P bonds are attractive targets for generating new ligand systems and also in catalysis.3 Interestingly, Amide-based bisphosphine 1 having CO and –NH functionalities in the ligand framework showed metathesis of C(sp2)–P bonds upon treatment with PdII and PtII precursors. The reactions of 1 with Pd(COD)Cl2 afforded κ 2-P,P complex 2 with in-situ formation of a phosphole ring involving nitrogen by tandem P–C bond breaking and P–N bond formation. Similar reactions of 1 with [Pd(COD)Cl2] in the presence of a base or with half equiv of [Pd(η 3-C3H5)Cl]2 yielded a PNP pincer complex 3 which on further treatment with anhydrous HCl produced a κ 2-P,P complex 2. Interestingly, the reaction of 1 with [Pt(COD)Cl2] resulted in the formation of a simple κ 2-P,P complex 7 which on subsequent treatment with LiHMDS produced a κ 2-P,P complex 8, resulting in a phosphole ring followed by the migration of a phenyl group from PPh2 to the PtII center. Complex 7 upon refluxing in toluene or treating 1 with [Pt(COD)Cl2] in the presence of a base afforded pincer complex 9. Mechanistic studies for the formation of complex 2 were carried out using NMR spectroscopy, DFT calculations and by single crystal X-ray data. The palladium complex 2 showed excellent activity for catalytic N-alkylation of amines with alcohols with very less catalyst loadings (0.05 mol %).
Tejmani
Tejmani
Probing the spatial distribution of monomers in a self-assembled block co-polymer using FRET microscopy
The single molecule (SM) level fluorescence measurements is able probe the molecular level interactions which otherwise be hidden in the ensemble level measurements. The length scale of these molecular interactions is much smaller than the conventional resolution limit (diffraction limit) of the microscope. The co-localization can be used to ensure the presence of the two interacting species within the area of ~250 nm (diffraction limit), but still it lacks in assuring the interaction. In such a case, fluorescence resonance energy transfer (FRET) can be used as a powerful technique to study and understand the molecular interaction in few angstroms length scale. FRET is a distance dependent physical process where the energy of a photo-excited fluorescent molecule (donor, D) transferred non-radiatively to another fluorophore (acceptor, A) by means of long-range intermolecular dipole-dipole interaction. It can serve a strong tool for the investigation of molecular interaction at a proximity of nanometer length scale (1-10 nm). Owing to its sensitivity to the distance, we used spatially and spectrally resolved FRET micro-spectroscopy to investigate the local distribution of fluorescent monomers with in a single supramolecular organic fibril, where the donors and acceptors self-assembled in a blocky fashion to form block co-polymer (BCP) (Figure 1(a)) [1]. The BCP shows a directional transfer of energy from the donor segment to acceptor with a high degree of sensitized acceptor emission at the interfaces (Figure 1(b)).
Jayanti
Jayanti
Elucidating the Allosteric regulation in the NtrC family Transcriptional Regulator, MopR and its application in the field of biosensor
MopR from Acinetobacter calcoaceticus is an AAA+ Enhancer Binding Protein (belongs to NtrC family of transcriptional regulators) that act as molecular machine involved in the remodeling of DNA with σ-54 dependent RNA polymerases and initiate transcription[1,2]. This remodeling is crucial for survival of the bacteria under stressful conditions such as those created by a toxic environment and/or by pathogenic bacteria for onset of virulence [2]. MopR possesses a modular design consisting of three major domains; a N-terminal signal reception (A) domain which binds phenol, followed by a central ATPase(C) domain responsible for ATP hydrolysis and a C-terminally located DNA binding (D) domain[1]. The ATP hydrolysis is foremost phenomena for DNA remodeling and is allosterically regulated via the phenol binding sensor domain. In the absence of phenol, the sensor domain adopts conformation that represses the ATPase activity whereas in the presence of the effector, de-repression takes place which restore ATP hydrolysis[1,2,3]. Additionally, it has been proposed that this event also results in signal transduction between domains and leads to shift in the protein population from a lower oligomeric (dimer) to a higher oligomeric assembly which then adopts a complex allostery mechanism of functioning[2]. The exact mechanism of phenol binding as well as depression and the allosteric regulation both intra- and inter- subunits is poorly understood. Therefore, here by employing a combination of crystallography and biochemical studies, we aim to develop allosteric models which describe the functioning of this mechanoenzymes. We have also engineered this protein so that it can respond to a broader spectrum of toxic aromatic compounds beyond its actual substrate scope for its application in the field of biosensors.
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