RESUMO
The charge neutral chiral optical sensors 1a-d containing thiourea and amide groups were synthesized by simple steps in good yields and their structures were characterized by IR, 1H NMR, 13C NMR, MS spectra and elemental analysis. The enantioselective recognition for alpha-phenylglycine and phenylglycinol was examined by fluorescence emission and UV-vis spectra. The fluorescence and UV-vis spectra changes of 1a were obvious when the enantiomers of alpha-phenylglycine anion were added, which exhibited that 1a has good enantioselective recognition ability towards alpha-phenylglycine.
Assuntos
Amidas/síntese química , Aminoácidos/análise , Técnicas Biossensoriais/métodos , Corantes Fluorescentes/síntese química , Tioureia/síntese química , Amidas/química , Corantes Fluorescentes/química , Estrutura Molecular , Sensibilidade e Especificidade , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Estereoisomerismo , Tioureia/químicaRESUMO
[structure: see text] The binding affinities of a cholic-acid-based fluorescent neutral receptor toward dicarboxylate anions and amino acids have been investigated in a CH3OH/H2O system (1:1, 0.01 M HEPES buffer, pH = 7.4) by fluorescence titration experiments. The synthetic host bearing four convergent functionalities strongly binds glutamate via multiple hydrogen bonds with a binding constant of (5.57 +/- 0.88) x 10(6).
Assuntos
Aminoácidos Acídicos/química , Técnicas Biossensoriais/métodos , Ácidos Cólicos/química , Ácidos Dicarboxílicos/química , Ânions/química , Sítios de Ligação , Fluorescência , Glutamatos/química , Ligação de Hidrogênio , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Água/químicaRESUMO
[structure: see text] The fluorescent photoinduced electron transfer (PET) chemosensors 1-3 were synthesized from cholic acid. 1 and 2 containing amidothiourea groups as anion receptive sites demonstrated much higher affinity toward anions than 3 containing traditional thiourea H-bond donating group. Comparative studies on their binding affinity toward carboxylates, dihydrogen phosphate, and halides revealed that the amidothiourea moiety on the C17 side chain could work cooperatively with H-bond donating groups on C7 and C12 to bind spherical halogen anions. An unexpected specific fluorescence enhancement of 1 by coordinating bromide ion was observed.
Assuntos
Ânions/análise , Técnicas Biossensoriais/métodos , Ácidos Cólicos/síntese química , Fluorescência , Ligação de Hidrogênio , Espectroscopia de Ressonância MagnéticaRESUMO
Two-armed neutral anion receptors (4,5), were prepared and examined for their anion-binding ability using UV-vis, fluorescence and 1H NMR spectra in DMSO. The results of non-linear curve fitting indicate that 4 or 5 form 1 : 1 stoichiometric complexes with dicarboxylate anions by multiple hydrogen bonding interactions and the sensitivity for recognition of dicarboxylate depends on the chain length of these dicarboxylate anions. Receptors 4 and 5 have no binding ability with acetate, dihydrogen phosphate and the halogen (Cl-, Br-, I-) anions. This demonstrates that receptors 4 or 5 could be used as chemical sensors for some special dicarboxylate anions.
