[show abstract][hide abstract] ABSTRACT: BACKGROUND: The title compound belongs to the class of bis-azomethine pigments. On the basis of comparative studies on similar structures, insight into the complex excited state dynamics of such compounds has been gained. It has been shown, for example, that only compounds that possess hydroxyl groups are fluorescent, and that the possibility for cis-trans isomerisation and/or bending motions of the central bis-azomethine fragment allows for different nondestructive decay pathways. RESULTS: The synthesis and structural characterization of 4,4[prime]-dihydroxy-1,1[prime]-naphthaldazine (1), was performed by means of spectroscopic and quantum chemical methods. The tautomerism of 1 was studied in details by steady state UV-Vis spectroscopy and time resolved flash photolysis. The composite shape of the absorption bands was computer processed using a program developed by us for decomposition of the spectra into individual subbands. Thus, the molar fraction of each component and the corresponding tautomeric constants were estimated from the temperature dependent spectra in ethanol. CONCLUSIONS: According to the spectroscopic data the prevalent tautomer is the diol form, which is in agreement with the theoretical (HF and DFT) predictions. The experimental data show, however, that all three tautomers coexist in solution even at room temperature. Relevant theoretical results were obtained after taking into account the solvent effect by the so-called supermolecule-PCM approach. The TD-DFT B3LYP/6-31 G** calculated excitation energies confirm the assignment of the individual bands obtained from the derivative spectroscopy.
Chemistry Central Journal 02/2013; 7(1):29. · 1.31 Impact Factor
[show abstract][hide abstract] ABSTRACT: A series of 22 symmetrical acyclic aromatic aldazines were obtained and their qualitative antimicrobial activities were evaluated against 10 bacterial and 3 fungal species. The results demonstrated that the bi-and polycyclic aromatics studied are remarkably more active than benzaldazines. The latter possess antibacterial activities only, which were dramatically reduced by the introduction of substituents. The tests showed that the activities are strongly dependent on the type and position of the substituents and that the effects on antibacterial and antifungal activities are the opposite. 2-Naphtaldazine was significantly more active than its position isomer 1-naphthaldazine against Saccharomyces cere-visiae and Penicillium chrysogenum, whereas both compounds possess commensurable activities towards Candida tropicalis and the bacterial strains. From the other side, the presence of 4-hydroxy substituent in 1-naphthaldazine re-duced the antibacterial and increased the antifungal activities, while the influence of 2-hydroxy group led to reversed results.
[show abstract][hide abstract] ABSTRACT: High performance liquid chromatography method for the separation of a series of chiral benzyl alcohols on N-(3,5-dinitrobenzoyl)-D-phenylglycine stationary phase (Macherey Nagel, Chiral-2) after pre-column achiral derivatization was developed. Cheap and easy available aromatic acid chlorides were used as derivatization agents. Good to excellent separations of the enantiomers were achieved in all cases in relatively short ana-lytical runs. It was shown that the enantiorecognition depends on the substituents both in the starting alcohol and in the acid chloride. The method presents an efficient alternative to the direct analyses on polysaccharide and cyclodextrine-derived stationary phases.
American Journal of Analytical Chemistry. 01/2010; 1:1-13.
[show abstract][hide abstract] ABSTRACT: 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 interaction between the metal ion captured in the macrocyclic moiety and the tautomeric carbonyl group. The complex formation is accompanied by strong bathochromic (between 60 and 100 nm) and hyperchromic effects on the absorption spectra. Obviously, the tautomeric OH/C=O groups play the role of an active side-arm in the complexation, supporting it via formation of a 3D cavity and giving possibility for ejection of the guest compound under stimuli to shift the tautomeric process back.