Hydrogen bonding and protonation effects in amino acids' anthraquinone derivatives - Spectroscopic and electrochemical studies

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Nov 5:222:117226. doi: 10.1016/j.saa.2019.117226. Epub 2019 Jun 2.

Abstract

Six novel amino acid chromophores were synthesized and their spectroscopic, acid-base, and electrochemical properties are discussed in this work. In studied compounds, selected amino acid residues (l-Aspartic acid, l-Glutamic acid, l-Glutamine, l-Histidine, l-Lysine, l-Arginine) are attached to the 1-(piperazine) 9,10-anthraquinone skeleton via the amide bond between the carboxyl group of amino acid and nitrogen atom of the piperazine ring. All derivatives have been characterized using a variety of spectroscopic techniques (mass spectrometry, 1HNMR, UV-Vis, IR spectroscopy), acid-base (electrochemical and UV-Vis) titrations, and cyclic voltammetry methods. Basing on observed experimental effects, supported by quantum chemical simulations, the structure-properties links were established. They are indicative of the specific interactions within and/or in-between amino acid side groups, which are prone to form both, intra- and intermolecular hydrogen bonds as well as electrostatic interactions with the anthraquinone system.

Keywords: Amino acids; Anthraquinone; Electrochemistry; Hydrogen bonding; Protonation; Pyroglutamic acid.

MeSH terms

  • Amino Acids / chemical synthesis
  • Amino Acids / chemistry*
  • Anthraquinones / chemical synthesis
  • Anthraquinones / chemistry*
  • Coloring Agents / chemical synthesis
  • Coloring Agents / chemistry*
  • Electrochemical Techniques
  • Hydrogen Bonding
  • Models, Molecular
  • Protons
  • Spectrophotometry, Ultraviolet

Substances

  • Amino Acids
  • Anthraquinones
  • Coloring Agents
  • Protons
  • 9,10-anthraquinone