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Updated: Jul 14, 2026

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores
Published on: August 19, 2013
Enantioselective fluorescent recognition of chiral acids by cyclohexane-1,2-diamine-based bisbinaphthyl molecules
Zi-Bo Li1, Jing Lin, Michal Sabat
1Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319, USA.
Abstract:
The cyclohexane-1,2-diamine-based bisbinaphthyl macrocycles (S)-/(R)-5 and their cyclic and acyclic analogues are synthesized. The interactions of these compounds with various chiral acids are studied. Compounds (S)-/(R)-5 exhibit highly enantioselective fluorescent responses and high fluorescent sensitivity toward alpha-hydroxycarboxylic acids and N-protected amino acids. Among these interactions, (S)-mandelic acid (10(-3) M) led to over 20-fold fluorescence enhancement of (S)-5 (1.0 x 10(-5) M in benzene/0.05% DME) at the monomer emission, and (S)-hexahydromandelic acid (10(-3) M) led to over 80-fold fluorescence enhancement. These results demonstrate that (S)-5 is useful as an enantioselective fluorescent sensor for the recognition of the chiral acids. On the basis of the study of the structures of (S)-5 and the previously reported 1,2-diphenylethylenediamine-based bisbinaphthyl macrocycle (S)-4, the large fluorescence enhancement of (S)-5 with a chirality-matched alpha-hydroxycarboxylic acid is attributed to the formation of a structurally rigidified host-guest complex and the further interaction of this complex with the acid to suppress the photoinduced electron-transfer fluorescent quenching caused by the nitrogens in (S)-5.
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