Amrita Chakraborty

Role of conformational isomerism in solvent-mediated charge transfer in chiral (S) 1,2,3,4-tetrahydro-3-isoquinoline methanol (THIQM): condensed-phase to jet-cooled spectroscopic studies.

Intramolecular charge-transfer reaction in chiral (S) 1,2,3,4-tetrahydro-3-isoquinoline methanol (THIQM) has been investigated in the condensed phase and in jet-cooled conditions by means of laser-induced fluorescence, dispersed emission, resonance-enhanced two-photon ionization, and IR-UV double resonance experiments, as well as quantum chemical calculations. In the condensed phase, THIQM only shows local emission in nonpolar and protic solvents and dual emission in aprotic polar solvents, where the solvent-polarity dependent Stokes shifted emission is ascribed to a state involving charge transfer from the nitrogen lone pair to the benzene π-cloud. Ab initio calculations reveal two low-energy conformers, which are observed in jet-cooled conditions. In the most stable conformer, THIQM(I), the CH(2)OH substituent acts as a hydrogen bond donor to the nitrogen lone pair in the equatorial position, while the second most stable conformer, THIQM(II), corresponds to the opposite NH···O hydrogen bond, with the nitrogen lone pair in the axial position. The two low-energy jet-cooled conformers of THIQM evidenced from the laser-induced fluorescence and dispersed emission spectra only show structured local emission. Complexes with usual solvents reproduce the condensed phase properties. The jet-cooled complex with aprotic polar solvent acetonitrile shows both local emission and charge transfer emission as observed in solution. The jet-cooled hydrate mainly shows local emission due to the unavailability of the nitrogen lone pair through intermolecular hydrogen bonding.

Photoinduced properties of methyl ester of 2,6-dimethyl-1-amino-4-benzoic acid: Evidence of charge transfer emission from a weak primary amino donor

Photophysical properties of methyl ester of 2,6-dimethyl-1-amino-4-benzoic acid (M26DMB) have been investigated using steady state absorption and emission spectroscopy and time-resolved emission spectroscopy. Interestingly, not only in polar solvents, the molecule M26DMB having a weak primary amino donor group shows broad red-shifted emission band even in non-polar environment which in all probability arises from closely spaced local and charge transfer (CT) states. Clear dual fluorescence in polar protic solvents comprises of less intense local emission band and strong red-shifted CT band. The position of the red-shifted emission band is dependent on both the polarity and the hydrogen-bonding ability of the solvent.

Promising Functional Lipids for Therapeutic Applications

Abstract Until a decade ago, dietary lipids were the most misunderstood and ill-perceived dietary component in the human diet in terms of its relation with health. However, modern day research has provided empirical evidence to show the potential of certain classes of specialty lipids and their coproducts as fast-acting nutraceuticals. Lipid-based dietary components have been shown to provide health benefits in addition to basic nutrition and, hence, are designated as functional lipids. Functional lipids, which also include structured lipids (manipulated from natural sources by bioprocess technology), impede the manifestations of chronic diseases. These functional lipid molecules, often stated as nutraceuticals, have specific mechanisms of action against major lifestyle diseases and which have now been identified. Clinical evidences are also available, which corroborate these findings. The present focus of researchers in the field of functional food technology is to develop such formulations, including bioactive lipids to improve compromised health parameters at the genomic level. This chapter essentially highlights the multidomain progress in lipid research to counter major health challenges, such as diabetes, cardiovascular diseases, arthritis, impaired cognition, and neurological diseases. In particular, the therapeutic role of eicosapentaenoic acid, docosahexaenoic acid, conjugated linoleic acid, conjugated linolenic acid, γ-linolenic acid, pinoleinic acid, phytosterols, and marine phospholipids are being discussed.

A Review on Potential of Proteins as an Excipient for Developing a Nano-Carrier Delivery System

In neo-age research, nano-materials have emerged as potential tools for the revolution of diagnostic and therapeutic field because of their nano-scale effects, increased surface area-volume ratio, and other beneficial properties. For the last few decades, protein has been regarded as the most attractive and versatile natural bio-macromolecule among all of the available biopolymers. Protein is largely exploited as a nano-carrier system in the pharmaceutical industry due to its low cytotoxocity, biocompatibility, biodegradability, abundant renewable sources, significant attaching ability, clinically useful targeting, and site-specific efficient uptake. This review mainly emphasizes on the latest development and progress achieved in the utilization of protein as a nano-vehicle for a large number of therapeutics such as drugs, genes, hormones, enzymse, nutraceuticals, antibodies, peptides, etc. We also discuss the sources of protein materials, fabrication aspects, advantages, constraints, in vivo and in vitro studies and provide a comparative analysis between the different types of proteins as nano-carriers. The variation of the release pattern and molecular mechanism of the encapsulated molecule with respect to different protein types and various nano-structures are also highlighted here to explore the enormous promises of this novel approach.