The emergence of resistance to antimicrobial and anticancer drugs poses severe threats to public health worldwide, highlighting the need for more efficient treatments. Here, four monoanionic Au bisdithiolate complexes [Au(mnt) 2 ]-(where mnt = 1,1dicyanoethylene-2,2-dithiolate)(1), [Au(i-mnt) 2 ]-(where i-mnt = 2,2-dicyanoethylene-1,1-dithiolate)(2), [Au(cdc) 2 ]-(where cdc = cyanodithioimido carbonate)(3), and [Au(qdt) 2 ]-(where qdt = quinoxaline-2,3-dithiolate)(4) were screened for their antimicrobial and antitumor activities. Complexes 3 and 4 showed antibacterial activity against Staphylococcus aureus (MIC = 15.3 and 14.7 µg/mL, respectively). Complex 3
The synthesis and characterization of (α-DT-TTF)2[Au(mnt)2] is reported. The magnetic properties of this new salt show that it is still a rare example of an organic spin-ladder. (α-DT-TTF)2[Au(mnt)2] shares the same ladder structure of the DT-TTF and ETT-TTF analogues, and its room temperature conductivity is ∼2 S/cm. Despite the observed donor orientation disorder associated with the thiophenic sulfur atoms, the intermolecular interactions between donor units, calculated using the extended Hückel approximation and a double-ξ basis set, show that the interaction values do not depend on the configuration of the sulfur atom on the thiophenic ring. The insensitivity of the spin-ladder magnetic properties to the donor molecular disorder in (α-DT-TTF)2[Au(mnt)2] is a direct consequence of the negligible contribution of the disordered thiophenic sulfur atom to the HOMO. In the related donor ETT-TTF, this contribution is significant and destroys the magnetic interactions, and no spin-ladder is observed. This compound not only enlarges the number of organic spin-ladder systems in this series of closely related compounds but also provides an interesting example of weakly disordered molecular spin-ladder system.
The electronic donor α‐DT‐TTF (α‐dithiophene‐tetrathiafulvalene), which among the thiophenic TTF derivatives has remained essentially unexplored, and some of its charge transfer salts are described in detail in this paper. This donor was efficiently prepared by the homocoupling of 5,6‐thieno[2,3‐d]‐1,3‐dithiol‐2‐one, and its redox properties are intermediate between those of DT‐TTF (dithiophene‐tetrathiafulvalene) and BET‐TTF [bis(ethylenethio)tetrathiafulvalene]. The crystal structure of α‐DT‐TTF shows a molecular packing composed of trios of donor chains with alternating orientation. This pattern is clearly distinct from those previously found in all other thiophenic TTF donors. Used as an active material in a field‐effect transistor, α‐DT‐TTF presents a mobility μFE = 5 × 10–5 cm2/V s. The possibility to convert this new donor to conducting charge‐transfer salts with suitable anions was demonstrated by preparing its PF6– salts. Two salts with different crystal structures and stoichiometries were identified by X‐ray diffraction studies: (α‐DT‐TTF)(PF6)0.6 and (α‐DT‐TTF)2(PF6). The electrical conductivities of these salts, measured in the single crystal, range from 9 to 50 S/cm at room temperature. In all cases, the salts show a semiconducting behaviour and properties that are comparable to those of the analogous nonaromatic BET‐TTF salts.
The Au and Ni monoanionic complexes of ter-buthyl and diisopropyl substituted thiophedithiolate ligand [M(α-tb-tpdt)2] and [M(α-dp-tpdt)2], were synthesized and characterized namely by single crystal X-Ray diffraction and magnetic susceptibility measurements. These complexes, prepared in a first step as monoanioc species, are easier to oxidized than the related nonsubstituted thiophenedithiolates and could be obtained also as stable neutral species, As expected, the peripheral alkyl groups in the ligands confer also to the complexes an high solubility in common organic solvents, The neutral gold complex [Au(α-tbtpdt)2] presents a significant ligand asymmetry indicative of unpaired electron localization in one ligand at variance with [Au(α-dp-tpdt)2] that is within experimental uncertainty fully symmetric illustrating the role of the intermolecular interactions in the stabilization of SOMO … SOMO interactions. While in [Au(α-tbtpdt)2] a significantr intermolecular interaction between paramagnetic molecules is possible leading to diamagnetic dimers of molecules, in [Au(α-dptpdt)2] the bulkier substituents prevent the intermolecular interactions, leading to a regular stacking of molecules in symmetrical configuration. The regular stacks of paramagnetic [Au(α-dp-tpdt)2] units behave at high temperatures as an antiferromagnetic chains undergoing an AFM transition at ca. 25 K.
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