Preparation of monomethine cyanine dyes as noncovalent labels for nucleic acids

By condensation of quaternary benzothiazolium, quinolinium and acridinium s alts having an active methyl group with 1-(3-bromopropyl)-4-chloroquinolini um or 1-(3-bromo-2-hydroxypropyl)-4-chloroquinolinium salts in the presence of a basic agent such as triethylamine, 8 asymmetric and symmetric monomet hine cyanine dyes bearing omega-bromopropyl substituent with one or two pos itive charges, were synthesized. Additionally, two of the dyes were quatern ized with pyridine, and monomethine cyanines with two and three positive ch arges are prepared. Most of the dyes showed high molar absorptivity (70 000 -100 0001 mol(-1) cm(-1)). The acridinium dyes showed broad peaks with lowe r intensity of 30 0001 mol(-1) cm(-1). In the presence of nucleic acid in a queous solutions, a strong enhancement of the fluorescence of these new dye s was observed. (C) 1998 Elsevier Science Ltd. All rights reserved.