Synthesis and in vitro evaluation of novel acyclic and cyclic nucleoside analogs with a thiadiazole ring.

5-diacetylamino-1,2,4-thiadiazol-3-one (1), 5-amino-2- (tetrahydrofuran-2-yl)-1,2,4-thiadiazol-3-one (2), 5-amino-3-[(2'-hydroxyethoxy)methyl]-1,3,4-thiadiazol-2-one (3), 5-amino-3-(4'-hydroxy-2'-hydroxymethyl-butyl)-1,3,4-thiadiazole-2-thione (4), (R)-5-amino-3-(2',3'-dihydroxypropyl)-1,3,4-thiadiazole-2-thione (5), and (S)-5-amino-3-(2',3'-dihydroxypropyl)-1,3,4-thiadiazole-2-thione (6). The synthesis, characterization, and properties of these new synthesized thiadiazole derivatives are discussed. A dimerization of 5-amino-3H-1,3,4-thiadiazole-2-thione (14) by sodium nitrite resulting in di-(5-amino-1,3,4-thiadiazol-2-yl) disulfide (19) is also reported.

Fluorescence properties and dipole moments of novel fused thienobenzofurans. Solvent and structural effects.

The electronic absorption, fluorescence excitation and emission spectra, and fluorescence quantum yields of novel fused thienobenzofurans, including thieno[3,2-b][1]benzofuran (1), [1]benzothieno[3,2-b]furan (2), and [1]benzothieno[3,2-b][1]benzofuran (3), were recorded in fourteen solvents of different polarities at room temperature. Compound 2 was not fluorescent. Experimental ground-state dipole moments of compounds 1-3 were measured in benzene at 298 K and compared with the corresponding theoretical dipole moment values.

Luminescence and photophysical properties of benzo[a]phenothiazines--therapeutic, physico-chemical, and analytical applications.

Luminescence studies on a series of new 12H-benzo[a]phenothiazines (BPHTs), possessing potentially useful antitumor therapeutic properties, are reviewed. The electronic absorption and fluorescence spectral properties of BPHTs, as well as their triplet- and singlet-excited states luminescence quenching are reviewed. Ground-state and singlet-excited state dipole moments and solvatochromic relationships are also described for these compounds.

Solvatochromic correlations and ground- and excited-state dipole moments of curcuminoid dyes.

Experimental dipole moments of curcumin (1) and of its parent compound dicinnamoylmethane (2) were determined in dioxane and benzene, respectively. Theoretical dipole moments were calculated using a combination of the PPP method (pi-moment) and a vector sum of the sigma-bond moments (sigma-moment) as well as by the ZINDO/1 method. Solvatochromic correlations were used to obtain the experimental first excited singlet-state dipole moments.