Detail publikace

4-OH coumarin based rotary switches: Tautomeric state and effect of the stator

YORDANOV, D. DENEVA, V. GEORGIEV, A. VASSILEV, N VALA, M. ZHIVKOV, I. ANTONOV. L

Originální název

4-OH coumarin based rotary switches: Tautomeric state and effect of the stator

Typ

článek v časopise ve Web of Science, Jimp

Jazyk

angličtina

Originální abstrakt

Two new 4-OH coumarin based rotary switches, containing fixed carbonyl groups in the rotor, have been synthesized and their properties have been studied by combined use of DFT calculations and molecular spectroscopy (UV-Vis absorbance and emission, NMR). It was found that the structure of the stator (naphthyl in 2 or quinolyl moiety in 3) and solvents polarity do not influence their azo-hydrazone tautomerism. Both compounds exist as keto (hydrazone) tautomers. The NMR data indicate a mixture of E (major) and Z (minor) keto form isomers in solution. The results are in very good agreement with ground state DFT calculations. The keto tautomers exhibit different emission behavior depending on the structure of the stators. Comparing to 2, more intensive emission and higher lifetime was observed in 3, where the formation of intramolecular hydrogen bonding of the hydrazone NH with the N atom of quinoline restricts the rotation of the stator. According to the spectral data and the TDDFT analysis the observed emission originates from the excitation of the keto tautomers and does not include excited state proton transfer. It was shown that the protonation is a suitable stimulus for E/Z switching in 2, where a possible mechanism is sketched. In the case of 3, the addition of acid leads to the pmtonation of the quinolyl nitrogen atom, which slightly affects the E/Z isomerization ratio.

Klíčová slova

4-Hydroxycoumarin; Rotary switch; Molecular spectroscopy; DFT; Tautomerism; Photochemistry

Autoři

YORDANOV, D.; DENEVA, V.; GEORGIEV, A.; VASSILEV, N; VALA, M.; ZHIVKOV, I.; ANTONOV. L

Vydáno

11. 1. 2021

Nakladatel

ELSEVIER SCI LTD

Místo

OXFORD

ISSN

0143-7208

Periodikum

DYES AND PIGMENTS

Ročník

184

Číslo

108861

Stát

Spojené království Velké Británie a Severního Irska

Strany od

1

Strany do

12

Strany počet

12

URL

https://www.sciencedirect.com/science/article/pii/S0143720820315588?via%3Dihub

BibTex

@article{BUT172907,
  author="YORDANOV, D. and DENEVA, V. and GEORGIEV, A. and VASSILEV, N and VALA, M. and ZHIVKOV, I. and ANTONOV. L",
  title="4-OH coumarin based rotary switches: Tautomeric state and effect of the stator",
  journal="DYES AND PIGMENTS",
  year="2021",
  volume="184",
  number="108861",
  pages="1--12",
  doi="10.1016/j.dyepig.2020.108861",
  issn="0143-7208",
  url="https://www.sciencedirect.com/science/article/pii/S0143720820315588?via%3Dihub"
}