Bis(1-pyrenylmethyl)-2-benzyl-2-methyl-malonate as a Cu2+ Ion-Selective Fluoroionophore

• Published in: Molecules (Basel, Switzerland) Vol. 22; no. 9; p. 1415
• Main Authors: Moriuchi-Kawakami, Takayo, Hisada, Youji, Higashikado, Akihisa, Inoue, Tsubasa, Fujimori, Keiichi, Moriuchi, Toshiyuki
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 25-08-2017; MDPI
• Subjects: Acetonitrile; Acids; bispyrenyl malonate; Chloroform; CH···π Interaction; Copper; Crystal structure; Crystallography; Cu2+ ion-selective; Emissions; Fluorescence; fluoroionophore; Hydrocarbons; Molecular structure; Pyrene; X-ray crystallographic analysis; X-ray crystallography; π···π interaction
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules22091415

A new malonate possessing two pyrene moieties was synthesized as a fluoroionophore, and its structure and fluorescence spectroscopic properties were investigated. When excited at 344 nm in acetonitrile/chloroform (9:1, v/v), the synthesized bispyrenyl malonate has the fluorescence of intramolecular excimer (λem = 467 nm) emissions and not a pyrene monomer emission (λem = 394 nm). A large absolute fluorescence quantum yield was obtained in the solid state (φPL = 0.65) rather than in solution (φPL = 0.13). X-ray crystallography analysis clarified the molecular structure and alignment of the bispyrenyl malonate in the crystal phase, elucidating its fluorescence spectroscopic properties. Such analysis also suggests there are intramolecular C-H•••π interactions and intermolecular π•••π interactions between the pyrenyl rings. Interestingly, the synthesized bispyrenyl malonate exhibits excellent fluorescence sensing for the Cu2+ ion. Remarkable fluorescence intensity enhancement was only observed with the addition of the Cu2+ ion.