Anion-induced isomerization of fluorescent semi(thio)carbazones. Issue 3 (20th October 2017)

• Record Type: Journal Article
• Authors: Amendola, Valeria; Boiocchi, Massimo; Fabbrizzi, Luigi; La Cognata, Sonia; Legnani, Laura; Lo Presti, Eliana; Mangano, Carlo; Miljkovic, Ana
• Is Part Of: Organic chemistry frontiers. Volume 5:Issue 3(2018)
• Page Start: 391
• Page End: 397
• Publication Date: 2017-10-20
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/c7qo00805h
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : An anion-controlled flapping motion has been observed in a series of novel semi(thio)carbazone molecules. Abstract : In this work, we have investigated the properties of novel fluorescent semi(thio)carbazone systems with anions by UV-vis, spectrofluorimetric and NMR studies, in acetonitrile and DMSO solutions. Conformational preferences were determined by theoretical calculations within the DFT approach. For the free receptors, these studies pointed out a marked prevalence of anti conformations, which are stabilized by intramolecular H-bonds between the (thio)urea NH group and the imino nitrogen atom. For the julolidine-based thiosemicarbazone system, intermolecular interactions involving the thiourea NH groups and the S atoms of two receptor molecules were also found in the crystals, leading to the formation of supramolecular dimers. Theoretical studies showed that anion binding involved a change of the conformation of the receptors from anti to syn . In the syn isomers, two NH groups actually point in the same direction, thus favouring the binding of anions, e.g. the Y-shaped acetate ion. This thorough study on the novel semi(thio)carbazones provides useful information for the application of this type of molecule in all the fields of chemistry, in which urea-based systems are employed ( e.g. anion recognition and transport, catalysis, soft materials, etc .).