New dithiolene derivatives as coordination chromophores: structural, spectroscopic, electrochemical, Hirshfeld surface analyses, and in-vitro cytotoxicity.

Seven substituted dithiolene systems with acetylacetonate, 3,4-dimethylpyrazole (HPz), and 3,4-dimethoxybenzyl moieties were synthesized by nucleophilic substitution, cyclocondensation, and transchalcogenation reactions. The seven compounds were characterized by NMR and X-ray diffraction techniques. The single-crystal X-ray diffraction analysis revealed that 4,5-bis[(2,4-dioxopentan-3-yl)sulfanyl]-1,3-dithiol-2-one, C13H14O5S4 or DMIO(acac)2, and 4,5-bis[(3,5-dimethylpyrazol-4-yl)sulfanyl]-1,3-dithiole-2-thione methanol monosolvate, C13H14N4S5·CH3OH or DMIT(HPz)2, crystallized in the triclinic P-1 and monoclinic P21/n space groups, respectively, while 4,5-bis[(3,4-dimethoxybenzyl)sulfanyl]-1,3-dithiole-2-thione, C21H22O4S5 or DMIT(3,4-dimethoxybenzyl)2, and 4,5-bis[(3,4-dimethoxybenzyl)sulfanyl]-1,3-dithiol-2-one, C21H22O5S4 or DMIO(3,4-dimethoxybenzyl)2, crystallized in the monoclinic space groups P21/n and P21/c, respectively. Methyl 4-({[5-({[4-(methoxycarbonyl)phenyl]methyl}sulfanyl)-2-sulfanylidene-1,3-dithiol-4-yl]sulfanyl}methyl)benzoate, C21H18O4S5 or DMIT(4-methylbenzoate)2, and methyl 4-({[5-({[4-(methoxycarbonyl)phenyl]methyl}sulfanyl)-2-oxo-1,3-dithiol-4-yl]sulfanyl}methyl)benzoate, C21H18O5S4 or DMIO(4-methylbenzoate)2, crystallized in the orthorhombic P212121 and monoclinic P21/n space groups, respectively. Similarly, 4-{[(5-{[(4-carboxyphenyl)methyl]sulfanyl}-2-oxo-1,3-dithiol-4-yl)sulfanyl]methyl}benzoic acid, C19H14O5S4 or DMIO(4-methylbenzoic acid)2, crystallized in the monoclinic space group P21/c. The molecular packings of the seven crystalline compounds were stabilized by a variety of intermolecular O...H, H...H, C...H, S...H, S...S, S...O, and N...H interactions, depending on the substituent group. Hirshfeld surface analysis confirmed the presence of the above-mentioned interactions and the percentage contributions of the interatomic contacts were determined by 2D fingerprint plots in the total Hirshfeld surface. Studies of the antiproliferative activity against the NCI-60 cell line panel were performed for selected 2-oxo-1,3-dithiole-4,5-dithiolate (DMIO) derivatives.