Fluorescence and quantum mechanical approach on the interaction of amides and their role on the stability and coexistence of the rotamer conformations of L-tryptophan in aqueous solution.

Photophysical investigation on the fluorescence decay characteristics of L-tryptophan and a derivative N-acetyl-L-tryptophanamide (NATA) with alkyl amides were carried out in water. L-tryptophan exists in the zwitterionic form and exhibits a biexponential lifetime which is correlated to the existence of rotamer structures. Addition of formamide (F) and dimethylformamide (DMF) results in a decrease in the fluorescence lifetime and its proportion of the most stable structure of L-tryptophan wherein acetamide (ACM) results in an increase of the same.

Electrostatic Investigation of 4-Dicyanomethylene-2,6-dimethyl-4-pyran (DDP) Dye with Amide Derivatives in Water.

Cyclic voltammetry (CV) studies of 4-dicyanomethylene-2,6-4-pyran (DDP) dye with alkyl-substituted amides were carried out in an aqueous solution. Formamide and substituted amide interaction with DDP dye were characterized by fluorescence spectral techniques in an aqueous solution, but the electrochemical nature and the interaction at the interface region between dye-amide remains largely unexplored. The introduction of formamide to DDP dye exhibits an increase in the peak current accompanied with potential values gradually shifting more toward a less positive region.

Fluorescence coupled with electrochemical approach at the bulk and the interface region of hydrogen-bonding self assemblies of urea derivatives with DDP dye in aqueous solution.

Photophysical and electrochemical techniques were employed to hydrogen-bonding self assemblies forming solutes (Urea, Dimethylurea and Tetramethylurea) in the presence of 4-dicyanomethylene 2, 6-dimethyl-4H-pyran (DDP) dye. Addition of urea derivatives to DDP dye (Intramolecular Charge Transfer (ICT)) results in a fluorescence enhancement accompanied with a significant shift. Fluorescence lifetime behavior exhibits a tri-exponential decay with a large variation in the fluorescence lifetime and relative amplitude distribution.

Fluorescence Spectral Studies on the Interaction of Alanine and Valine with Resorcinol-Based Acridinedione Dyes in Aqueous Solution: A Comparative Study with Glycine.

Photophysical studies were carried out for simple amino acids like alanine and valine with resorcinol-based aqueous acridinedione (ADDR) dyes. ADDR dyes exhibit interesting excited-state characteristics on altering the substituents at the 9th and 10th sites (Scheme 1). The longest-wavelength absorption maxima remain the same on adding the amino acids to the fluorophore, whereas the excited-state behavior varies significantly mostly based on the nature of the substituent at the 9th position.

Photophysical and Electrochemical Studies of 4-Dicyanomethylene 2,6-Dimethyl-4H-Pyran (DDP) Dye with Amides in Water.

Photophysical and electrochemical studies of DDP dye with Formamide and alkyl substituted amides were carried out in water. Addition of Formamide (F), Acetamide (ACM), N,N-Dimethylformamide (DMF), Dimethylacetamide (DMAC) to DDP dye result in an isosbestic point. A fluorescence enhancement of DDP dye is observed on the addition of amides.