The Synthesis and Fluorescent Properties of Analogues of the Zinc(II) Specific Fluorophore Zinquin Ester

Abstract

The synthesis and fluorescent properties in the absence and presence of zinc(II) of a range of 2-substituted derivatives of N-(6-methoxy-2-methyl-8-quinolyl)-4-methylbenzenesulfonamide are described. These analogues formed complexes with zinc(II) as indicated by a bathochromic shift in their UV/vis spectra. Analogues with isobutenyl and isobutyl side chains at the 2-position formed fluorescent complexes whose fluorescence was stronger than that of the 2-methyl-containing parent. These derivatives were converted, via conversion to the phenol with boron tribromide and reaction with ethyl bromoacetate, to systems with ester-containing side chains analogous to zinquin ester, a specific cellular fluorophore for zinc(II). All of these ester derivatives formed complexes with zinc(II) resulting in a bathochomic shift in their UV/vis spectra. Compounds with isobutyl, isobutenyl, and styryl side chains exhibited increased fluorescence compared to that of zinquin ester in the presence of zinc(II). The compound with the 2-isobutyl side chain was more selective in its fluorescence for zinc(II) over cadmium(II) compared to zinquin ester.

The use of the zinc‐fluorophore, Zinpyr‐1, in the study of zinc homeostasis in Arabidopsis roots

“…Particular chemical modifications enable a membrane‐permeable probe to be converted to an impermeable derivative through enzymatic modification in the cell. An example of this is the hydrolysis of an ethyl ester group on the Zinquin probe by endogenous cellular esterases (Kimber et al ., 2000). Zinc fluorophores have been used for imaging Zn in vivo in animal cells, particularly in neural cell biology where, for example, Zn appears to modulate neurotransmission and the disruption of neuronal zinc homeostasis is associated with Alzheimer's disease (Woodroofe et al ., 2004; Kay et al ., 2006).…”

3-[2-(8-Quinolinyl)benzoxazol-5-yl]alanine derivative—a specific fluorophore for transition and rare-earth metal ion detection

“…11,12 Depending on the 8-quinoline derivative used, this chemosensor is selective to Zn 2C or Cd 2C ions. [9][10][11][12] In spite of the presence of numerous fluorescence sensors, [4][5][6][7][8] there is still a need for new ones-more selective and sensitive. In this paper we describe a new chemosensor containing an 8-quinoline moiety appended to position 2 of 3-(benzoxazol-5-yl)-alanine (Bx(8-Q)) ( Fig.…”

A tautomeric zinc sensor for ratiometric fluorescence imaging: Application to nitric oxide-induced release of intracellular zinc

“…Several families of fluorescent Zn 2ϩ probes have been described, including those with peptide-or protein-based scaffolds (18)(19)(20)(21)(22). There are also a number of cell-permeable, synthetic chemosensors that induce a change in fluorescence intensity upon Zn 2ϩ binding and do not require microinjection for intracellular use (23)(24)(25)(26)(27)(28)(29)(30). Although these and related (31,32) intensity-based fluorescent probes are of considerable practical value, they cannot provide quantitative information about changes in Zn 2ϩ concentrations, owing to variations in excitation intensity, emission collection efficiency, sample thickness, and artifacts associated with probe concentration and environment.…”