A SYSTEM WHICH CAN “TUNE” DRUGS
TO PERFECT THEM INTO MORE POTENCY
ABOUT THE PROJECT
Traditionally our research is focused to organic and hybrid systems used as dyes, indicators, sensing and NLO materials.Molecular spectroscopy (UV-Vis-NIR, IR/ Raman, fluorescence, NMR and mass spectrometry) and quantum chemistry are used as tools.In other words we are on the border between physical organic and organic analytical chemistry, depending on the viewpoint.
First tautomeric compounds have been reported more than 120 years ago. But even now, the study of the tautomerism and proton transfer mechanism remains a challenge. Tautomeric processes are in the basis of the information transfer/storage in the living organisms and tautomeric systems are used as photoprotectors, molecular switches, laser dyes, optical sensors, etc.
We have concentrated our efforts to investigate equilibrium tautomeric systems, i.e. the tautomers co-exist in solution. They cannot be experimentally separated and analyzed conventionally. Due to the methods for quantitative analysis of undefined mixtures we have developed many tautomeric systems have been investigated quantitatively and structure – tautomeric properties relations have been found.
Three are the main classes of tautomeric systems we have studied.
Keto-enol tautomerism in azodyes and Schiff bases:
Important information about the effects of the substituents, strength of the intramolecular hydrogen bonding, solvents, temperature and acidity have been found by using conventional UV-Vis spectroscopy and advanced chemometrics, steady-state and time-dependent fluorescence, quantum chemistry and linear solvation energies relationships. As a result, using the accumulated knowledge, we have developed a tautomeric molecular switch, which allows directed shift in the position of the tautomeric equilibrium in 1-phenylazo-4-naphthol under addition of acid or metal ions.
Ammonium-azonium tautomerism in protonated amino azodyes: Depending on the structure and substituents a clear color change is observed under protonation, allowing these dyes to be used as pH-indicators.
Tautomerism, stability and aggregation of heterocyclic compounds: Here we have studied the tautomeric properties and stability of thiopyridines and pyrimidines and the concentration effects on the tautomerism in 2-aminobenzimidazole.
Exploiting the tautomerism for switching/signaling purposes. L.Antonov, V.Deneva, S.Simeonov, V.Kurteva, D.Nedeltcheva & J.Wirz;
Angewandte Chemie International Edition, 48, 7875 (2009) Tautomerism in 1-phenylazo- 4-naphthols: experimental results vs quantum-chemical predictions. L.Antonov, V.Kurteva, A.Crochet, L.Mirolo, K.Fromm & S.Angelova;
Dyes & Pigments, 92, 714 (2012) Chemometric models for quantitative analysis of tautomeric Schiff bases and azodyes. D.Nedeltcheva, L.Antonov, A.Lycka, B.Damyanova & S.Popov; Current Organic Chemistry, 13, 217 (2009)
Tautomerism in hydroxynaphthaldehyde anils and azo analogues: a combined experimental and computational study.
STEP BY STEP FILTER
Smart approach to increase the information, which can be extracted by using derivative spectroscopy
Program for resolution of overlapping bands and quantitative spectral analysis of undefined (with unknown individual spectra of the components) mixtures
Program for resolution of charge transfer absorption/ emission bands