Polymorphism of Au11(PR3)7Cl3 clusters: understanding C–H⋯π interaction and C–H⋯Cl–C van der Waals interaction on cluster assembly by surface modification

C–H⋯π interactions and C–H⋯Cl–C van der Waals interactions are dominant in the crystallization of Au₁₁(PR₃)₇Cl₃ clusters, resulting in a crystal system transformation.

Synthesis and structures of polyiodide radical cation salts of donors combining tetrathiafulvalene with multiple thiophene or oligo-thiophene substituents

The preparation and structures of the radical cation salts of a series of new TTF-based donors bearing thiophene or oligothiophene side chains with polyiodide counterions are described.

Molecular docking of polyoxometalates as potential α-glucosidase inhibitors

α-Glucosidase is an important target enzyme for the treatment of type 2 diabetes in humans. In our previous studies, it was found that polyoxometalates exhibited an effective inhibitory effect on the activity of α-glucosidase, while polyoxometalates have the characteristics of structural diversity and unique properties. Herein, we investigated the inhibition of two different series of polyoxometalates on α-glucosidases by enzyme kinetics and molecular docking. The results demonstrated that all of the studied compounds had a significant inhibitory ability on α-glucosidase as compared with the positive control acarbose. H₈[P₂Mo₁₇Cr(OH₂)O₆₁] reversibly inhibited α-glucosidase in a competitive manner with IC₅₀ of 115.50 ± 1.64 μM and K_I value of 44.31 μM. All other compounds reversibly inhibited enzymatic activity in a mixed manner. H₆PMo₉V₃O₄₀ and H₈[P₂Mo₁₇Cu(OH₂)O₆₁] were the best inhibitors in the Keggin and Dawson series, respectively, with IC₅₀ of 9.63 ± 0.43 and 40.13 ± 0.61 μM, respectively. We conducted molecular docking study and found that the compound and α-glucosidase were mainly non-covalently interacting with hydrogen bonds and van der Waals forces. This result further confirmed the inhibition mechanism of enzyme kinetic experiments.

A weaker donor shows higher oxidation state upon aggregation

The charge-transfer between TTFs and I₂ shows that the stronger donor TTF1 is in a cation radical state and the weaker donor TTF2 is neutral in solution, whereas TTF1 exists as a cation radical and TTF2 is dicationic in complexes. The dicationic and neutral states of TTF2 are reversible upon aggregation and solvation.

A weaker donor is dicationic but a stronger donor appears as a cation radical in their CT complexes with iodine.

Crystal structure of ethyl-ene-dioxy-tetra-thia-fulvalene-4,5-bis-(thiol-benzoic acid) 0.25-hydrate

In the title compound (systematic name: 4,4'-{[2-(5,6-di-hydro-[1,3]di-thiolo[4,5-b][1,4]dioxin-2-yl-idene)-1,3-di-thiole-4,5-di-yl]bis-(sulfanedi-yl)}di-benzoic acid 0.25-hydrate), C22H14O6S6·0.25H2O, the tetra-thia-fulvalene (TTF) core adopts a boat conformation, where the central S2C=CS2 plane makes dihedral angles of 31.34 (4) and 26.83 (6)°, respectively, with the peripheral S2C=CS2 and S2C2O2 planes. In the crystal, the benzoic acid mol-ecules are linked via O-H⋯O hydrogen bonds, forming inversion dimers with R22(8) motifs. The dimers are linked through weak C-H⋯O hydrogen bonds into a chain structure along [-101]. The chains stack along the a axis through S⋯S and S⋯C short contacts, forming layers parallel to the ac plane.

Aryl-fused tetrathianaphthalene (TTN): synthesis, structures, properties, and cocrystals with fullerenes

A library of aryl-fused TTN has been synthesized to show shape complementary with fullerene molecules and form “TTN·fullerene” cocrystals.

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

The combination of CuBr2 and arylthio-substituted tetrathiafulvalene derivatives (1-7) results in a series of charge-transfer (CT) complexes. Crystallographic studies indicate that the anions in the complexes, which are derived from CuBr2, show diverse configurations including linear [Cu(I)Br2](-), tetrahedral [Cu(II)Br4](2-), planar [Cu(II)2Br6](2-), and coexistence of planar [Cu(II)Br4](2-) and tetrahedral [Cu(II)Br3](-) ions. On the other hand, the TTFs show either radical cation or dication states that depend on their redox potentials. The central TTF framework on most of TTFs is nearly planar despite the charge on them, whereas the two dithiole rings on molecule 4 in complex 4·CuBr4 are significantly twisted with a dihedral angle of 38.3°. The magnetic properties of the complexes were elucidated. The temperature-dependent magnetic susceptibility of complex 5·Cu2Br6 shows the singlet-triplet transition with coupling constant J = -248 K, and that of 3·(CuBr4)0.5·CuBr3·THF shows the abrupt change at 270 K caused by the modulation of intermolecular interactions. The thermo variation of magnetic susceptibility for the other complexes follows the Curie-Weiss law, indicating the weak antiferromagnetic interaction at low temperature.