Chemical and bacterial reduction of azo-probes: monitoring a conformational change using fluorescence spectroscopy

Nicholas J.W. Rattray, Waleed A. Zalloum, David Mansell, Joe Latimer, Mohammed Jaffar, Elena V. Bichenkova, Sally Freeman

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Sterically constrained probes 2,4-O-bisdansyl-6,7-diazabicyclo[3.2.1]oct-6- ene (8) and 2,4-O-bispyrenoyl-6,7-diazabicyclo[3.2.1]oct-6-ene (9) exhibit specific dimer fluorescent characteristics (λmax 555 nm and 511 nm, respectively), attributed to the 2,4-diaxial arrangement of the dansyl or pyrene groups. Reduction of the azo-conformational locking group in (8) and (9) yielded 1,3-bisdansyl-4,6-diaminocyclohexane (16) and 1,3-bispyrenoyl-4,6- diaminocyclohexane (17) in the tetra-equatorial chair conformation, thus minimising interaction of the bisdansyl or bispyrenoyl groups. This induces a change in fluorescence from a cooperative green emission dimer band to a blue-shifted, monomer type fluorescence, with λmax 448 nm and 396 nm for the reduced forms (16) and (17), respectively. The azo-bond conformational lock can either be reduced under biomimetic conditions (using sodium dithionite) or with bacteria (Clostridium perfringens or Escherichia coli) utilising azo-reductase enzymes. These fluorescent probes have the potential to specifically detect azo-reductase expressing bacteria.

Original languageEnglish
Pages (from-to)2758-2766
Number of pages9
Issue number13
Early online date8 Feb 2013
Publication statusPublished - 1 Apr 2013


  • azo-reductase
  • conformational lock
  • dimer
  • escherichia coli
  • fluorescent probe

Cite this