Dicarboxylated ethynylarenes as buffer-dependent chemosensors for Cd(II), Pb(II), and Zn(II)

Abstract

Two dicarboxylated ethynylarenes were prepared efficiently from condensation of 1,3-bis(3-aminoph enylethynyl)benzene with two equivalents of either succinic anhydride or glutaric anhydride. These compounds behave as fluorescent chemosensors selective for Cd(II), Pb(II) and Zn(II) cations under buffered aqueous conditions, with analyte binding observed as bathochromically shifted, intensified fluorescence. It was noteworthy that the fluorescence responses varied significantly with buffer identity. A conformational restriction mechanism involving reversible interactions between the fluorophore, metal cation and buffer itself is proposed.

Spermine detection via metal-mediated ethynylarene ‘turn-on’ fluorescence signaling

“…[41] The initial group of polyamines evaluated were spermine ( 2 ), spermidine ( 3 ), ethylenediamine ( 4 ), 1,3-diaminopropane ( 5 ), putresceine ( 6 ), cadaverine ( 7 ), 1,6-diaminohexane ( 8 ), 1,7-diaminoheptane ( 9 ) and 1,8-diaminooctane ( 10 ) (Figure 2). In addition to the four major biogenic polyamines ( 2, 3, 6, 7 ), this group includes diamines with shorter ( 4, 5 ) and longer ( 8–10 ) carbon chain spacing in order to gain insight into the ability of this system to discriminate between similar aliphatic polyamines.…”

“…This response is nearly identical to that previously observed for TRIS buffered systems. [41] While the intensity of the turn-on response varies significantly as metal cation and analyte components are varied, the bathochromic shift itself is largely independent of metal cation or polyamine identity, changing by no more than 5 nm among the conditions studied. In the absence of metal cation or polyamine, 1 displays a fluorescence quantum yield of 0.41% (ϕ F = 0.0041) under aqueous conditions for its 345 nm emission band.…”

“…[41] Polyamine analytes spermine ( 2 ), spermidine ( 3 ), ethylenediamine ( 4 ), 1,3-diaminopropane ( 5 ), putrescine ( 6 ), cadaverine ( 7 ), 1,6-diaminohexane ( 8 ), 1,7-diaminoheptane ( 9 ), 1,8-diaminooctane ( 10 ), diethylenetriamine ( 11 ), N -(2-aminoethyl)-1,3-propanediamine ( 12 ), bis(3-aminopropyl)amine ( 13 ), triethylenetetramine ( 14 ), N -(2-aminoethyl)- N -3-aminopropylethylene diamine ( 15 ), N,N′ -bis(2-aminoethyl)-1,3-propanediamine ( 16 ), 1,2-bis(3-aminopropylamino)ethane ( 17 ), N,N′ -bis(3-aminopropyl)-1,3-propanediamine ( 18 ) and tris(2-aminoethyl)amine ( 19 ) were used as purchased from Aldrich. CdCl 2 , PbCl 2 and ZnCl 2 were used as purchased from Strem.…”

“…[41] Notably, the bathochromic shifts in fluorescence emission displayed by this system in pH = 7.6 aqueous conditions were only observed for buffer molecules possessing one amine unit and at least one additional heteroatom, such as in TRIS, MOPS and HEPES. [41] It was demonstrated that the ‘turn-on’ fluorescence signal generated by this sensor was promoted by a three-component association, which was proposed to include a coordinate interaction between buffer and transition metal as well as an electrostatic interaction between the carboxylate unit of the sensor and the ammonium unit of the buffer. [41]…”

“…[41] It was demonstrated that the ‘turn-on’ fluorescence signal generated by this sensor was promoted by a three-component association, which was proposed to include a coordinate interaction between buffer and transition metal as well as an electrostatic interaction between the carboxylate unit of the sensor and the ammonium unit of the buffer. [41]…”