SYNTHESIS AND STUDY OF SPECTRAL PROPERTIES OF AMINO ACIDS – BODIPY CONJUGATES

Abstract

The present work describes direct one-pot synthesis of the two novel amino acids – boron-dipyrromethene (BODIPY) conjugates with histidine and tyrosine residues bound to fluorophore via amino group. The synthesized compounds were fully characterized by means of 1H and 11B nuclear magnetic resonance spectroscopy, infrared spectroscopy, time-of-flight mass spectrometry with matrix-activated laser desorption / ionization. All the data are in accordance with the proposed structures. The amino acids – BODIPY conjugates under study were investigated by means of absorbance and fluorescence spectroscopy. Absorption and emission spectra of the compounds in dimethyl sulfoxide (DMSO) – buffer solution (BS) mixture (1:1) were obtained. Moreover, a number of photophysical characteristics of the conjugates, namely: relative fluorescence quantum yield, molar extinction coefficient, relative fluorescence lifetime, radiative and non-radiative rate constants were calulated. 3D fluorescence spectra of the compounds in DMSO – BS mixture (1:1) were obtained. Absorption and emission titration of the compounds was carried out. The results of the titration allowed us to confirm additionally a stoichiometric composition of the conjugates. Quantum chemical analysis of structural and spectral properties of the compounds in a ground state was carried out. The results of quantum chemical calculations gave an insight to a nature of the BODIPY – amino acid interactions in the conjugates. Besides, the synthesized amino acids – BODIPY conjugates are found to be highly soluble in polar solvents. Thus, a range of unique properties of the objects of the present research enables us to use them for visualization of bioactive macromolecules as well as biochemical processes in living cells.