Sintesis Kemosensor Ion Hg(II) Berbasis Hemisianin

Abstract

In this study, hemicyanine-based chemosensor was successfully synthesized from 3-(carboxymethyl)-2-methylbenzotiazolium bromide (kmb salt) and 4- diethylamino-2-hydroxybenzaldehyde through condensation reaction. Hemicyanine product was (E)-2-(2-(4-(diethylamino)-2-hydroxystyryl)benzo[d] thiazol-3-ium-3-yl)acetate (hemicyanine 1). Kmb salt and hemicyanine 1 were characterized using 1H nuclear magnetic resonance and Fourier transform infrared spectroscopy. The presence of Hg(II) ions shifted the maximum absorption wavelength from 541 to 462.5 nm. The ability of hemicyanine 1 to selectively recognize Hg(II) ions was evidenced by solution color change from red to yellowish green. The role of –OH group on selectivity and sensitivity of hemicyanine 1 toward Hg(II) ions was proven by synthesizing another hemicyanine compound without –OH group, that was (E)-2-(2-(4- (dimethylamino)styryl)benzo[d]thiazol-3-ium-3-yl)acetate (hemicyanine 2). Ultraviolet-visible spectrum of hemicyanine 2 with Hg(II) ions did not shift the maximum absorption wavelength and did not change the color of hemicyanine solution. As the result, hemicyanine 2 cannot be used as chemosensor for Hg(II) ions.