Synthesis, redox properties, and basicity of substituted 1-aminoanthraquinones: spectroscopic, electrochemical, and computational studies in acetonitrile solutions

Abstract

1-Amino-, 1-ethylamino-, and 1-(diethylamino)anthraquinone were characterized by UV-Vis spectroscopy, acid-base titration, electrochemical methods, and quantumchemical (QM) calculations at the B3LYP/6-31 ??G ** level. Acid-base titration and the relative differences between the free energies of the basic and acidic forms of the studied species show that 1-(diethylamino)anthraquinone is the strongest base in an acetonitrile solution. Moreover, the structural differences between the B3LYP-optimized neutral and protonated anthraquinones, notably the presence or the absence of internal hydrogen bonds, account well for the sequence of the measured/calculated basicity. The basicity of the investigated compounds strongly influences their electrochemical properties in acetonitrile. Indeed, the cyclic voltammograms of 1-aminoanthraquinone and 1-(ethylamino)anthraquinone display two well-resolved reduction waves that indicate a two-step reduction process (EE mechanism). On the other hand, the electroreduction of 1-(diethylamino)anthraquinone becomes complicated by the interaction of its reduced forms with traces of water present in an acetonitrile solution (ECE mechanism). The mechanism of this reaction is proposed, and its possibility to occur is examined based on QM calculations.

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

“…Several hypotheses of the mechanism responsible for reversible photodegradation in DO11/PMMA have been proposed, including intramolecular proton transfer and dimer formation [46], twisted intramolecular charge transfer [55], and domain-assisted reversible photodegradation [51,56,57], none have been experimentally proven. These hypotheses, together with anion formation [58,59] and protonation [60,61] of dye molecules observed in similar systems, have been investigated and the results suggest that they are unlikely responsible for reversible photodegradation of 1-substituted aminoanthraquinone derivatives doped in PMMA and PS [49].…”

“…These hypotheses, together with anion formation [58,59] and protonation [60,61] of dye molecules observed in similar systems, have been investigated and the results suggest that they are unlikely responsible for reversible photodegradation of 1-substituted aminoanthraquinone derivatives doped in PMMA and PS [49].…”

Molecule Confined Isolated Metal Sites Enable the Electrocatalytic Synthesis of Hydrogen Peroxide

“…[ 12 ] For the isolated AQNH 2 molecule, the band at around 310 nm is associated with the benzenoid character of the molecule, and the absorption around 480 nm is caused by the nitrogen atom of the amine group at position 1 of anthraquinone. [ 13 ] We note that NiN x /C‐AQNH 2 shows the same absorption peaks as compared with the isolated AQNH 2 molecule, demonstrating that AQNH 2 exists on NiN x /C. X‐ray photoelectron spectroscopy (XPS) results also indicate the successful introduction of AQNH 2 on NiN x /C.…”

New anticancer zinc(II) complexes comprising thiosemicarbazones of saturated ring: structure, DNA/protein binding, DNA cleavage, topoisomerase‐1 inhibition and anti‐proliferation studies

“…The K app values found are 6.86 × 10 5 and 4.90 × 10 5 M −1 for 1 and 2 , respectively, which reveals that 1 has a stronger binding affinity to DNA than 2 . This clearly demonstrates that the unsubstituted amino groups of 1 can form stronger hydrogen bonds with the polyanionic backbone of DNA …”

“…This clearly demonstrates that the unsubstituted amino groups of 1 can form stronger hydrogen bonds with the polyanionic backbone of DNA. [33] The decrease in fluorescence of the DNA-EB system hints at the intercalation mode of binding. However, the complexes also quench the fluorescence of DNA-groove binder (Hoechst) system ( Fig.…”