π-Stacking among the Anthracenyl Groups of a Copper Complex Resulted in Doubling of Unit Cell Volume To Provide New Polymorphs

Two polymorphs of the 9-N-(3-imidazolylpropylamino)methylanthracene (Hanthraimmida) containing hydrated copper(II)-2,6-pyridinedicarboxylate complex are reported. The two polymorphs have either lamellar or Herringbone arrangements of π-stacks among the anthracenyl groups of organocation. The difference between the two polymorphs originated from having face-to-face stacking arrangements between the two anthracenyl groups of the symmetry independent cations within the unit cell in one of the polymorphs. The π-stacked anthracenyl groups in consecutive layers of the polymorphs are oriented in one direction in the polymorph designated as P1, whereas the polymorph designated as P2 has such orientations in opposite directions. The unit cell volume of the polymorph P2 (Z = 4) has approximately twice the volume of the polymorph P1 (Z = 2); it happend due to coalescence of two unit cells of P1 in the ab-crystallographic plane. A mixed methanol/water solvate of the copper complex is also reported. It has a channel-like arrangement of the cations; has the anions and the solvents within the cation embraced channel-like enclosures. This complex is unstable, once taken out from the methanol solvent, it transforms in real time to P2 by replacements of the methanol molecules by water molecules.

Conformation and Visual Distinction between Urea and Thiourea Derivatives by an Acetate Ion and a Hexafluorosilicate Cocrystal of the Urea Derivative in the Detection of Water in Dimethylsulfoxide

Structures of different solvates and solute-solvent interactions of 4-(3-(4-nitrophenyl)urido)benzoate (L ₁ ) and methyl-4-(3-(4-nitrophenyl)thiourido)benzoate (L ₂ ) with different solvents are analyzed. The solution of L ₁ with tetrabutylammonium acetate (TBAA) in dimethylsulfoxide (DMSO) is colorless, but a similar solution of L ₂ with TBAA is orange. On the other hand, respective solutions of these urea and thiourea derivatives with tetrabutylammonium fluoride (TBAF) in DMSO are orange. Urea derivative L ₁ facilitates the reaction of TBAF with glass to form tetrabutylammonium hexafluorosilicate, which on further interaction with L ₁ forms cocrystal 2L ₁ ·(TBA)₂SiF₆. Reorganization of hydrogen-bonded self-assembly of 2L ₁ ·(TBA)₂SiF₆ in DMSO caused by water is established by a dynamic light scattering study. With an increase in the amount of water in the solution, visual color changes from orange to colorless, and the color changes are reversed upon the addition of a dehydrating agent such as molecular sieves. Solvates of L ₁ with DMSO, dimethylformamide (DMF), and dimethylacetamide are quasi-isostructural. The respective self-assembly of these solvates differs due to orientations of aromatic rings and the carbomethoxy group across the thioamide/amide bond. Significant differences in self-assemblies of the respective DMSO solvate of L ₁ and L ₂ are observed; self-assembly of the former has dimeric subassemblies as repeat units, whereas the latter has monomeric subassemblies. DMF solvates of L ₁ and dimethylacetamide of L ₁ are built by dimeric subassemblies to form self-assembled structures, but these subassemblies differ in the orientation of the carbomethoxy group across the urea units.