New mono- and di-branched derivatives of Kryptofix K22 with N-4-methoxyamino-3,5-dinitrobenzoyl substituents. Synthesis and properties

Starting from the Kryptofix 22 azacrown compound, mono-and di-branched derivatives have been synthesized, by coupling with one or two 4-chloro-3,5-dinitrobenzoyl chloride units and then substituting the chlorine(s) on the aromatic ring(s) with methoxyamine. The two new compounds were characterized by IR, NMR, and UV-Vis spectra; they are soluble in organic solvents, yielding a yellow color, which is changing to blue in the presence of a base (such as alkali metal hydroxides), thus acting as colorimetric chemosensors. The ratios of complexation and extraction constants with alkali metal cations were measured.