Elmes_2022_Head.pdf (2.96 MB)
Download file

Head vs. Tail Squaramide–Naphthalimide Conjugates: Self-Assembly and Anion Binding Behaviour

Download (2.96 MB)
journal contribution
posted on 2023-03-14, 11:34 authored by Anthony A Abogunrin, Stephen A. Healy, Orla Fenelon, Robert B.P. Elmes

The syntheses of two squaramide–naphthalimide conjugates (SN1 and SN2) are reported; the structures of SN1 and SN2 differ by the attachment of a squaramide—either at the ‘head’ or the ‘tail’ of the naphthalimide fluorophore. Both compounds displayed weak fluorescence due to the inclusion of a nitro-aromatic squaramide which efficiently quenches the emission of the naphthalimide. Both compounds were also shown to undergo self-aggregation as studied by 1H NMR and scanning electron microscopy (SEM). Furthermore, SN1 and SN2 gave rise to stark colourimetric changes in response to basic anions such as AcO−, SO4 2− HPO4 2−, and F−. The observed colour changes are thought to be due to deprotonation of a squaramide NH. The same basic anions also result in a further quenching of the naphthalimide emission. No colour change or emission modulations were observed in the presence of Cl−; however, 1H NMR studies suggest that moderate H-bonding occurs between this anion and both SN1 and SN2. 


Strategic Funds

Science Foundation Ireland

Find out more...

SFI Research Infrastructure - Cat D - Opportunistic Funding

Science Foundation Ireland

Find out more...




Chemistry 4(4), pp. 1288-1299



Also affiliated with

  • Synthesis and Solid State Pharmaceutical Centre

Department or School

  • Chemical Sciences