Substitution enables significant new decay channels for a non-canonical amino acid.

UV-Vis absorption spectra and emission peaks of indole and 7-fluoroindole are measured and it is observed that 7-fluoroindole quenches the fluorescence signals significantly compared to indole. This observation is elucidated reconstruction of the potential energy surfaces, determination of the conical intersections, and dynamical studies. It is observed that a single fluorine substitution on indole leads to the appearance of several accessible low-energy conical intersections that cause fast nonradiative decay.

Photophysical Properties of Noncanonical Amino Acid 7-Fluorotryptophan Sharply Different from Those of Canonical Derivative Tryptophan: Spectroscopic and Quantum Chemical Calculations.

Due to the limited number of naturally existing canonical amino acids, several noncanonical amino acids have been designed to understand the diverse complex biological functions. Fluorinated amino acids are one of the important noncanonical amino acids that have been used to understand the different complex processes of proteins. In this study, the photophysical properties of the noncanonical amino acid 7-fluorotryptophan (7F-Trp) in different solvents have been investigated using extensive spectroscopic as well as quantum chemical calculation methods and compared with those of tryptophan (Trp).

Solvent organization around the noncanonical part of tyrosine modulates its fluorescence properties.

Noncanonical amino acids are important molecules that enhance the functionality of proteins, and they are also intensively used in therapeutics. In this paper, we have investigated the fluorescence properties of the noncanonical amino acid 2-(trifluoromethyl) tyrosine (TFTyr) in three different alcohols, namely ethanol (ETH), monofluoroethanol (MFE), and trifluoroethanol (TFE), using spectroscopy, quantum chemical calculations and MD simulations. Further, we have compared its fluorescence properties with those of its canonical derivative tyrosine (Tyr) in the same solvents to understand the role of the noncanonical -CF3 group in the fluorescence properties of TFTyr.

Understanding the Role of Hydrophobic Terminal in the Hydrogen Bond Network of the Aqueous Mixture of 2,2,2-Trifluoroethanol: IR, Molecular Dynamics, Quantum Chemical as Well as Atoms in Molecules Studies.

The aqueous mixture of 2,2,2-trifluoroethanol (TFE) is one of the important alcoholic solvents which has been extensively used for understanding the stability of proteins as well as several chemical reactions. In this paper, the deconvolution of the IR lines in the OH-stretching region has been applied to understand the local structure of water-water, alcohol-water, and alcohol-alcohol interactions in the water mixture of TFE and ethanol (ETH). Further, molecular dynamics simulations, quantum chemical calculations, and atoms in molecules analysis have been performed to encode the local structure information obtained from the experimental data.

Hydrophobic fluorine mediated switching of the hydrogen bonding site as well as orientation of water molecules in the aqueous mixture of monofluoroethanol: IR, molecular dynamics and quantum chemical studies.

The local structures between water-water, alcohol-water and alcohol-alcohol have been investigated for aqueous mixtures of ethanol (ETH) and monofluoroethanol (MFE) by the deconvolution of IR bands in the OH stretching region, molecular dynamics simulation and quantum chemical calculations. It has been found that the addition of a small amount of ETH into the aqueous medium increases the strength of the hydrogen bonds between water molecules. In an aqueous mixture of MFE, the substitution of a single fluorine induces a change in the orientation as well as the hydrogen bonding site of water molecules from the oxygen to the fluorine terminal of MFE.