Hydrogen bonding or deprotonation: on fluoride ion fluorescence sensing with 1,1′-bi-2-naphthol derivatives

Abstract

The isolation and structural characterisation of two ionic complexes (S)-3 and(S)-4 based on fluoride ion-mediated deprotonation of 1,1′-bi-2-naphthol (BINOL) derivatives (S)-1 and (S)-2 have been carried out for the first time. X-ray crystallographic study showed that the deprotonated forms (S)-3 and (S)-4 adopt remarkably different molecular geometries, bond parameters as well as molecular packing modes from their neutral analogs, in agreement with their significant fluorescence changes upon the addition of fluoride ion, giving insights into the actual mechanism of fluoride ion fluorescence sensing. The deprotonation–protonation processes in two BINOL derivatives were also investigated by both fluorescence measurements and X-ray structural analyses. Such chiral basic compounds can be promising organocatalysts for asymmetric reactions.

Abstract

The isolation and structural characterisation of two ionic complexes based on fluoride ion-mediated deprotonationon BINOL derivatives have been carried out for the first time. The deprotonation–protonation processes in two BINOL derivatives were studied by fluorescence measurements and structural analyses.

Keywords::

• BINOL
• deprotonation
• fluoride ion
• fluorescent sensor
• crystal structure

Funding

Funding for this work was provided by a Seed grant from the Office for the Advancement of Research at CUNY John Jay College.