Polyazapodands derived from biphenyl. Study of their behaviour as conformationally regulated fluorescent sensors

Ana M. Costero, Joaquín Sanchis, Salvador Gil, Vicente Sanz, M. Carmen Ramírez De Arellano, J. A.Gareth Williams

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)

Abstract

Eight new polyazapodands containing a 4,4′-substituted biphenyl moiety have been synthesised. Four (7, 8, 9 and 11) are functionalised on positions 4 and 4′ with a nitro group and four (1, 2, 3 and 10) with a dimethylamino substituent. Comparison of the emission behaviour of 1, 2, 3 with that of the reference compounds 10 and tetramthylbenzidine, clearly suggests that a modification in the dihedral angle between the biphenyl rings is an important factor in determining the fluorescent response of the molecule. The fluorescence is pH dependent, due to the formation of intramolecular hydrogen bonds between protonated aliphatic nitrogens and a carbonyl oxygen, which influences the aforementioned dihedral angle. A crystal structure resolved by X-ray diffraction of 7·2HCl has been determined, and confirms the dependence of the angle and the rigidity on the hydrogen bonding. The complexation properties of these ligands have been studied with Zn2+, Cd2+, Ni2+, Cu2+ and Pb2+, which show that the number of amino groups within the pendants has a strong influence on the nature of the complexation and the fluorescent response of each ligand.

Original languageEnglish
Pages (from-to)435-446
Number of pages12
JournalSupramolecular Chemistry
Volume16
Issue number6
DOIs
Publication statusPublished - 1 Sept 2004
Externally publishedYes

Keywords

  • Conformational regulation
  • Fluorescent sensors
  • Tetramethylbenzidine

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