Enantioselective fluorescent recognition of chiral acids by cyclohexane-1,2-diamine-based bisbinaphthyl molecules.
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.
Li
Zi-Bo
ZB
Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904-4319, USA.
Lin
Jing
J
Sabat
Michal
M
Hyacinth
Marilise
M
Pu
Lin
L
D000144:Acids, Acyclic; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D003514:Cyclohexylamines / Q000138:chemical synthesis / Q000737:chemistry*; D047028:Macrocyclic Compounds / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008333:Mandelic Acids / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism
D000144:Acids, Acyclic; D003514:Cyclohexylamines; D047028:Macrocyclic Compounds; D008333:Mandelic Acids; D009281:Naphthalenes; C030435:1,2-cyclohexanediamine; C037938:mandelic acid