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A comparative study was conducted to evaluate the chiral recognition ability of several inherently chiral calixcrown carboxylic acids towards chiral aminoalcohols. 1 H NMR titration experiments indicated that inherently chiral calixcrown carboxylic acids each having a phenolic hydroxyl group possess superior chiral recognition ability to the completely alkylated calixarene derivatives. Particularly, inherently chiral calix[4]crown-6 carboxylic acid cone conformer 10 demonstrated significant enantioselectivity in its chiral recognition towards 2-amino-3-methyl-1-butanol (G3) and 2-amino-2-phenylethanol (G6), with the (cS)-10 preferably binding the (S)-guests. Job plots confirmed that 10 and both enantiomers of G3/ G6 form 1 : 1 instantaneous complexes. DFT calculations revealed the existence of multiple hydrogen bonds in the host-guest complexes. The enantioselectivity of the recognition is ascribed to the stronger hydrogen bonding between (cS)-10 and (S)-guests than between (cS)-10 and (R)-guests, based on the calculation results.

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Two new rhodamine-based fluorescent probes were synthesized and characterized by NMR, high resolution mass spectrometer (HR-MS) and IR. The probes displayed a high selectivity for Fe(3+) among environmentally and biologically relevant metal ions in aqueous solution (CH3OH-H2O = 3 : 2, v/v). The significant changes in the fluorescence color could be used for naked-eye detection. Job's plot, IR and (1)H NMR indicated the formation of 1: 1 complexes between sensor 1 and Fe(3+). The reversibility establishes the potential of both probes as chemosensors for Fe(3+) detection. The probe showed highly selectivity in aqueous solution and could be used over the pH range between 5 and 9. A simple paper test-strip system for the rapid monitoring of Fe(3+) was developed, indicating its convenient use in environmental samples.