The synthesis of new aminothiazole derivatives on the basis of substituted 1,4-naphthoquinones was carried out by the interaction of 2-R-3,6-dichloro-7-acylamino-1,4-naphthoquinones and potassium thiocyanate, 3,6-dichloro-2,7-diacylamino-1,4-naphthoquinone and dithiocyanate, of 2-R-3,6-dichloro-7-amino-1,4-naphthoquinones, 2-amino-7-nitro-3,6-dichloro-1,4-naphthoquinone and thiourea with the subsequent cyclization in aminothiazoles of 1,4-naphthoquinone. The physical and chemical properties of these compounds were determined, and the methods of their preparation are presented. The PASS computer program was used to predict the biological activity spectra of the new 1,4-naphthoquinone aminothiazole derivatives and to determine the most promising biological activities for experimental testing. Antibacterial and fungicidal activities were studied using the cultures of Staphylococcus aureus, Escherichia coli and Candida tenuis microorganisms. Some of the study compounds were found to have a moderate antibacterial and fungicidal activity, which in more than 90 % of cases coincided with the computational predictions. The analysis of the structure – antimicrobial activity relationships provides recommendations for the design of the new derivatives. Some other biological activities have been predicted by PASS for these compounds, including antiviral, antineoplastic, immunomodulating, acute neurological disease treatment, antiparkinsonian, etc., which help to identify areas for the further research. Thus, the 1,4-naphthoquinone aminothiazole derivatives have been shown to be a promising class for the preparation of novel pharmacological agents with different applications.
Cheminė Technologija, 2012, Nr. 3 (61) 62-69.

Interaction of anions with thiourea-linked acridinedione fluorophore was studied by absorption, 1H NMR, steady-state and time-resolved fluorescence techniques. Addition of AcO and H2PO4 shows a genuine H-bonded complex with thiourea receptor; whereas, F shows stepwise H-bonding and deprotonation of thiourea NH as confirmed by 1H NMR titration. Free receptor 1 shows emission maximum at 418 nm; whereas, Hbonded complex of 1·F shows a new redshifted emission maximum at 473 nm and the deprotonated 1 exhibits an emission peak at 502 nm. Presence of these three different emitting species was probed by 3D emission spectroscopic studies. Equilibrium between the free receptor 1, 1·F H-bonded complex and deprotonated 1 was confirmed by time-resolved fluorescence studies. Time-resolved area normalised emission spectra (TRANES) of 1 in the presence of F shows two isoemissive points at 456 and 479 nm between time delays of 0–0.5 ns and 1–20 ns, respectively, due to the existence of three emitting species in equilibrium. Observation of such an equilibrium based on fluorescence spectroscopic studies further proves the earlier reported absorption and 1H NMR spectroscopic studies of H-bonding and deprotonation processes and also illustrates the dynamics of anion-receptor interactions
Chem. Eur. J. 2010, 16, 13271 – 13277