A Preparative and Preliminary Spectroscopic Study of Analogues of a Zinquin-Related Fluorophore

Abstract

The syntheses of the 4- and 5-methoxy isomers of 4-N-(6-methoxy-2-methyl-8-quinolyl)-4-methylbenzenesulfon-amide and of N-(2-methoxy-8-quinolyl)-4-methylbenzenesulfonamide are described. The 6-methoxy compound is a precursor of Zinquin ester, a specific fluorophore for Zn(II). The 2-methoxy analogue was synthesized by nitration of 2-chloroquinoline and subsequent functional group manipulation. The 4-methoxy isomer was synthesized from a 4-quinolone derivative, and the 5-methoxy isomer was synthesized by a standard Skraup quinoline synthesis. The structures of the 4- and 5-methoxy isomers were determined by single-crystal X-ray analysis. All of these compounds showed a bathochromic shift in their ultraviolet/visible spectra upon addition of Zn(II) to the solution. These compounds are all weakly or non-fluorescent in solution. All form fluorescent complexes with Zn(II) except the 5-methoxy compound. The 4-methoxy compound forms a significantly more fluorescent complex than those of the 6-methoxy compound and Zinquin ester and has a higher quantum yield than the others.

Preparation of New Bis(8‐aminoquinoline) Ligands and Comparison with Bis(8‐hydroxyquinoline) Ligands on Their Ability to Chelate CuII and ZnII

“…2-Chloro-8-nitroquinoline: Was synthesized as described previously. [27] More precise NMR spectroscopic data than previously published are given, and other unpublished characterizations are added. 1 (23 mg, 37 µmol).…”

Characterization of New Specific Copper Chelators as Potential Drugs for the Treatment of Alzheimer’s Disease

“…The first step consisted of nitration at position C8 to afford 8-nitro-2-chloroquinoline 3 according to a published procedure. [22] The following steps are depicted in Figure 2 and Figure 3, for 1 and 2, re-spectively. The w-amine side chain was first coupled by nucleophilic substitution of chlorine at C2, to provide compounds 4 and 8, respectively, bearing a secondary amine at C2.…”

2,4,6-Triisopropyl-N-(6-methoxy-2-methyl-8-quinolyl)benzenesulfonamide

“…Compound (I) was prepared according to the procedure described by Kimber et al (2003). Single crystals of (I) suitable for X-ray data collection were obtained by recrystallization from a methanoldichloromethane (1:1) solvent mixture (m.p.…”