Université de Fribourg

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

Deneva, Vera ; Dobrikov, Georgi ; Crochet, Aurélien ; Nedeltcheva, Daniela ; Fromm, Katharina M. ; Antonov, Liudmil

In: Beilstein Journal of Organic Chemistry, 2019, vol. 15, no. 1, p. 1898–1906

The concept for sensing systems using the tautomerism as elementary signaling process has been further developed by synthesizing a ligand containing 4- (phenyldiazenyl)naphthalene-1-ol as a tautomeric block and an amide group as metal capturing antenna. Although it has been expected that the intramolecular hydrogen bonding (between the tautomeric hydroxy group and the nitrogen atom from the...

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

A concept for stimulated proton transfer in 1-(phenyldiazenyl)naphthalen-2-ols

Hristova, S. ; Deneva, Vera V. ; Pittelkow, M. ; Crochet, Aurélien ; Kamounah, Fadhil S. ; Fromm, Katharina M. ; Hansen, P. E. ; Antonov, Liudmil

In: Dyes and Pigments, 2018, vol. 156, p. 91-99

A series of aryl azo derivatives of naphthols (1–3) were studied by means of UV–Vis and NMR spectroscopy in different solvents as well as by quantum chemical calculations and X-ray analysis. Previous studies have shown that Sudan I (1) exists as a tautomeric mixture. The effect of the solvents is minimized by the existing intramolecular hydrogen bond. Therefore, the influence on the...

Université de Fribourg

Controlled tautomeric switching in azonaphthols tuned by substituents on the phenyl ring

Antonov, Liudmil ; Deneva, Vera ; Simeonov, Svilen ; Kurteva, Vanya ; Crochet, Aurélien ; Fromm, Katharina M. ; Shivachev, Boris ; Nikolova, Rositsa ; Savarese, Marika ; Adamo, Carlo

In: ChemPhysChem, 2015, vol. 16, no. 3, p. 649–657

A series of new tautomeric azonaphthols are synthesized and the possibilities for molecular switching are investigated using molecular spectroscopy, X-ray analysis and density functional theory quantum chemical calculations. Two opposite effects that influence switching are studied: attaching a piperidine sidearm, and adding substituents to the phenyl ring. On the one hand, the attached...

Université de Fribourg

Controlled tautomerism – switching caused by an ‘underground’ anionic effect

Antonov, Liudmil ; Deneva, Vera ; Kurteva, Vanya ; Nedeltcheva, Daniela ; Crochet, Aurélien ; Fromm, Katharina M.

In: RSC Advances, 2013, vol. 3, no. 47, p. 25410–25416

In a previous communication, we demonstrated a conceptual idea for a tautomeric switching system based on implementation of a flexible piperidine unit in 4- (phenyldiazenyl)naphthalen-1-ol (1). The results showed that a directed shift in the position of the tautomeric equilibrium can be achieved through protonation/deprotonation in a number of solvents. However, the effect of the counter ion...

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

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...