Sensitized terbium(iii) macrocyclic-phthalimide complexes as luminescent pH switches

Gaoyun Chen, Nicholas J. Wardle, Jason Sarris, Nicholas P. Chatterton*, S. W Annie Bligh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Four new macrocyclic-phthalimide ligands were synthesised via the coupling of N-(3-bromopropyl)phthalimide either to cyclen (1,4,7,10- tetraazacyclododecane) itself or its carboxylate-functionalized analogues, and photophysical studies were carried out on their corresponding Tb(iii) complexes in aqueous media as a function of pH. Luminescence intensities of Tb·L1a-Tb·L3a were in 'switched off' mode under acidic conditions (pH < 4), and were activated on progression to basic conditions as the phthalimido functions therein were hydrolysed to their corresponding phthalamates Tb·L1b-Tb·L3b. Emission of phthalamate-based macrocyclic Tb(iii) complexes Tb·L 1b-Tb·L3b was in 'switched on' mode between pH 4 and 11, exhibiting high quantum yields (Φ) and long lifetimes (τ) of the order of milliseconds at pH ∼ 6. Tb(iii) emissions were found to decline with increasing number of chromophores. The values of Φ and τ were 46% and 2.4 ms respectively for Tb·L1b at pH ∼ 6 when activated. This is the best pH-dependent sensor based on a Tb(iii) complex reported to date, benefiting from the macrocyclic architecture of the ligand.

Original languageEnglish
Pages (from-to)14115-14124
Number of pages10
JournalDalton Transactions
Volume42
Issue number39
Early online date19 Jul 2013
DOIs
Publication statusPublished - 21 Oct 2013
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry

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