Naphthalimide‐Containing Isomeric Urea Derivatives: Mechanoluminescence and Fluoride Recognition. Issue 11 (21st September 2017)

• Record Type: Journal Article
• Authors: Devi, Kakali; Sarma, Rupam J
• Is Part Of: ChemPhotoChem. Volume 1:Issue 11(2017)
• Page Start: 524
• Page End: 531
• Publication Date: 2017-09-21
• Subjects: anion sensing -- fluoride -- mechanoluminescence -- naphthalimide -- urea; Photochemistry -- Periodicals; Periodicals; Electronic journals; 541.35
• DOI: 10.1002/cptc.201700123
• Languages: English
• ISSNs: 2367-0932

Abstract

Abstract: Isomeric ortho, meta and para naphthalimide–urea derivativesND‐2U, ND‐3U andND‐4U were synthesized and characterized. Upon gentle mechanical stimulation, the weakly emissive ortho isomeric sampleND‐2U was transformed into a yellow‐green emissive material ( λ em =500 nm), with Δ λ ≈125 nm. The mechanoluminescent emission of this isomer could be "switched off" by exposing the sample to solvent vapour. Moreover, ND‐2U could respond to fluoride anions in solution with a dramatic enhancement of fluorescence at λ =446 nm. The sigmoidal nature of the binding isotherm suggested cooperative binding of fluoride to the ortho isomer. 1 H NMR spectroscopic studies provided vital insights into the nature ofND‐2U /F − complexation, highlighting the role of the proximal 1, 8‐naphthalimide motif. Abstract : The daily grind : The mechanoluminescent behaviour of naphthalimide‐containing urea derivatives varies depending on the isomeric linkage positions. The geometrically constrained ortho isomer shows reversible mechanoluminescent switching with Δ λ ≈125 nm in the solid state. Moreover, in solution the isomer recognises fluoride anions with distinct cooperativity, characterised by a sigmoidal binding isotherm.