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Pavol Tisovsky, Speaker at Chemical Engineering Conferences
Comenius University, Slovakia (Slovak Republic)
Title : Photochemical and thermal reactivity of bipyridyl-functionalized hydrazones and their ON / OFF functionality


Arylizatin hydrazones in the presence of basic ions (F-, CH3 COO- ) provide the corresponding anions by the NH group hydrogen cleavage located on the hydrazone moiety. The charge delocalization in the anion molecule is reflected in the UV-VIS spectra by the formation of a new, intensively batochromically shifted absorbent band. Hydrazone 1 titration with fluoride ions results in formation of new intensive but hypsochromically shifted absorbent band. By NH-hydrogen substitution for the methyl group is achieved the fact that the UV-VIS titration record is the same as in the above cited works – with hypsochromically shifted absorbent band. The different behavior of the studied hydrazones in the presence of F- ions is illustrated on the scheme 1.

By the NH hydrogen cleavage from the hydrazone, respectively B1-Z or B2-Z anion formation, the intramolecular hydrogen bond is extinguished. The thermodynamic stability of the Z isomer is reduced. Suitable conditions for the thermal Z-E isomerization of anion A2-Z, respectively B2-Z are formed. In the case of hydrazone 1, the N-anion A1-Z transformation to anion B1-Z must be carried out first. Anions C1-E and C2-E are photochemically transformed to Z isomers of this anions and they undergo the thermic Z-E isomerization again.

Audience Take Away:

  • The audience can get information about behavior of new bipyridyl-functionalized hydrazones.
  • This information can help them to use hydrazones as photoswitches in their research.
  • This work can help other researchers to explain behavior of hydrazones in the presence of basic anions.


Pavol Tisovský has completed his PhD in organic chemistry from Comenius University in Bratislava in 2014. He is the researcher in the Institute of Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Slovakia. He has published 9 papers in SCI(E) journals. His research interests are materials for organic electronics and two photochemistry areas: molecular photoswitches and colorimetrical/fluorescent chemo-sensors.