Université de Fribourg

Betti bases from 4-(3-pyridazo)-1-naphthol: synthesis, coordination behaviour and unusual substitution reactions

Kurteva, Vanya B. ; Lubenov, Lubomir A. ; Shivachev, Boris L. ; Nikolova, Rositsa P. ; Fromm, Katharina M.

In: ChemistrySelect, 2018, vol. 3, no. 43, p. 12017–12021

A series of Betti bases from 4‐(3‐pyridyl)azo‐1‐naphthol dye, possessing flexible methylene or more constrained aryl‐methyne spaced NH‐containing side‐chains, were obtained and characterized. It was shown by NMR spectroscopy that the ligands exist in keto form. The products’ structure was confirmed by single crystal XRD of a selected sample. A study on the coordination ability...

Université de Fribourg

4-Hydroxy-1-naphthaldehydes: proton transfer or deprotonation

Manolova, Y. ; Kurteva, Vanya B. ; Antonov, Liudmil M. ; Marciniak, H. ; Lochbrunner, S. ; Crochet, Aurélien ; Fromm, Katharina M. ; Kamounah, Fadhil S. ; Hansen, P. E.

In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 15, p. 10238–10249

A series of naphthaldehydes, including a Mannich base, have been investigated by UV-Vis spectroscopy, NMR and theoretical methods to explore their potential tautomerism. In the case of 4-hydroxy-1-naphthaldehyde concentration dependent deprotonation has been detected in methanol and acetonitrile. For 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (a Mannich base) an intramolecular proton...

Université de Fribourg

Switching azonaphthols containing a side chain with limited flexibility. Part 1. Synthesis and tautomeric properties

Kurteva, Vanya B. ; Antonov, Liudmil ; Nedeltcheva, Daniela V. ; Crochet, Aurélien ; Fromm, Katharina M. ; Nikolova, Rositsa P. ; Shivachev, Boris L. ; Nikiforova, Maya S.

In: Dyes and Pigments, 2012, vol. 92, no. 3, p. 1266–1277

A series of azo dyes, possessing amide fragments with restricted flexibility tethered to 4-(phenyldiazenyl)naphthalen-1-ol, was obtained from 1-hydroxy-2-naphthoic acid by subsequent conversion to amides and diazo coupling. It was shown that the position of the tautomeric equilibrium in solution strongly depends on the solvent in both UV and NMR concentration scale. The compounds exist as...

Université de Fribourg

(E)-1-(4-Methoxyanthracen-1-yl)-2-phenyldiazene

Crochet, Aurélien ; Fromm, Katharina M. ; Kurteva, Vanya B. ; Antonov, Liudmil

In: Acta Crystallographica Section E, 2011, vol. 67, no. 4, p. o993

The title compound, C₂₁H₁₆N₂O, has an E-conformation about the diazene N=N bond. It is reasonably planar with the phenyl ring being inclined to the mean plane of the anthracene moiety [planar to within 0.077 (3) Å] by 6.43 (10)°. The crystal structure is stabilized by C-H..π and weak π-π interactions [centroid-centroid distances of 3.7192 (16) and 3.8382 (15) Å],...

Université de Fribourg

Tautocrowns: a concept for a sensing molecule with an active side-arm

Antonov, Liudmil ; Kurteva, Vanya B. ; Simeonov, Svilen P. ; Deneva, Vera V. ; Crochet, Aurélien ; Fromm, Katharina M.

In: Tetrahedron, 2010, vol. 66, no. 24, p. 4292-4297

A new sensing molecule containing aza-15-crown-5 as a receptor and 4- (phenyldiazenyl)naphthalen-1-ol as a signal converter has been synthesized. In the free ligand, the hydrogen bonding between the tautomeric OH group and the nitrogen atom from the macrocycle fully shifts the tautomeric equilibrium towards the enol form. The complexation reverses the equilibrium as a result of the strong...