Novel Mg-responsive fluorescent chemosensor based on benzo-15-crown-5 possessing 1-naphthaleneacetamide moiety

A new fluorescent ionophore for Mg²⁺, 4′-(1-naphthaleneacetamido)benzo-15-crown-5 (1), was synthesized, and its complexation behavior in acetonitrile was investigated by means of UV and fluorescence spectrometry. In the absence of a metal ion, the naphthalene moiety showed quite weak fluorescence emission (fluorescence ‘Off’ state). On the other hand, after the addition of Mg²⁺, fluorescence emission from the naphthalene moiety increased (fluorescence ‘On’ state).     

The "off-on" fluorescence detection of alkaline earth metal ions by using 1-naphthylacetanilide derivatives: new cation sensors based on oligo-ethylene oxides connecting 1-naphthylacetanilide at its terminals.

New fluorescent ionophores containing the 1-naphthylacetanilide moiety based on oligo-ethylene oxide (1(4) and 1(5)) have been synthesized, and their photochemical behaviors have been studied. In the absence of a metal ion, the 1-naphthylacetanilide moiety showed a weak fluorescence emission (fluorescence "off state"). However, complexation with Ca(2+) induced a large enhancement effect on the fluorescence intensity of 1(4) and 1(5) from the naphthalene ring (fluorescence "on" state). This behavior can be explained in terms of a similar twisted intramolecular charge-transfer relaxation mechanism. Such "off-on" fluorescence responses of 1(4) and 1(5) provide the digital detection of alkaline earth metal ions.     

Control of photochemistry of stilbazolium ion by adsorption to poly(potassium vinylsulfate) and to hectorite clay

Adsorption or intercalation of trans-1-methyl-4-(2-phenylvinyl)pyridinium ion (stilbazolium ion, SB ( 1 )) to a polyelectrolyte, i. e., poly(potassium vinylsulfate) (PVSK), and to a hectorite clay is studied and its effect on the photochemistry of SB examined. trans-cis Photoisomerization of SB molecularly adsorbed to PVSK proceeds efficiently as with free SB in water, while that of SB molecularly intercalated in the clay is markedly suppressed. Photodimerization proceeds efficiently with SB intercalated in the clay in the aggregated form. Overall photodecoloration, however, proceeds more efficiently with SB adsorbed to PVSK under multiple adsorption conditions apparently due to the higher mobility of PVSK-adsorbed SB compared to that of clay-intercalated SB.