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

Abstract

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 2 L 1 ·(TBA) 2 SiF 6 . Reorganization of hydrogen-bonded self-assembly of 2 L 1 ·(TBA) 2 SiF 6 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.

Water‐Assisted Emission Enhancement of 2‐Hydroxynaphthaldoxime and Related Compounds

“…The assembly also has several C−H⋅⋅⋅Cl interactions (Figure b). This assembly is a rare example of organic ionic cocrystal of quaternary ammonium salt holding two oximes as guest molecules. The complex on dissolution in DMSO showed similar emission features as that of the parent oxime.…”

Neutral, Zwitterion, Ionic Forms of 5‐Aminoisophthalic Acid in Cocrystals, Salts and Their Optical Properties

“…[20][21][22][23][24] The electrostatic interactions in the noncovalent self-assemblies of inorganic complexes are common. [25][26][27][28] Among many examples of organic salts forming cocrystals the salts of active pharmaceutical ingredients, [25] carboxylic acid, [20][21][22][23][24] quaternary ammonium [29] and heterocycle containing oximes [30] are well studied. Depending on the reactivity of a base dicarboxylic acids form salts with different stoichiometries.…”

Substitution Effect on Near Infrared Absorbance Based Selective Fluoride Sensing of Indole Functionalized Thiourea Molecules

“…DMF for crystallization of the ligands as well as their anion adducts, which may nullify the effect of solvent on conformational change of thiourea during crystallization. [12a] Moreover, as evidenced from the single‐crystal X‐ray structures, the dihydrogen phosphate anion binds with the receptors not via two thiourea NH groups, which, in general leads to conformational changes at that center. Rather, it forms non‐covalent bonds with imidazole NH group keeping the conformation around thiourea center intact.…”

“…Synthesis of Compound S1‐S6: All the indole aldehydes were prepared following relevant literature procedure. [12b] A solution of corresponding indole‐3‐aldehyde (2 eqv.) in ethanol (20ml) was added slowly to a solution of thiocarbohydrazide or carbohydrazide (1 eqv.)…”