2-{(E)-2-[(3E)-2-Chloro-3-{(2E)-2-[1,1-dimethyl-3-(3-phenylpropyl)-1,3-dihydro-2H-benzo[e]indol-2-ylidene]-ethylidene}cyclohex-1-en-1-yl]ethenyl}-1,1-dimethyl-3-(3-phenylpropyl)-1H-benzo[e]indolium Iodide

Eric Owens,Maged Henary,Joseph Tawney

doi:10.3390/m814

Abstract

In four synthetic steps we successfully prepared a red-shifted heptamethine cyanine dye (λmax = 825 nm in methanol) that could be very useful for biochemists and bioanalytical chemists for probing lipophilic environments, including the hydrophobic pockets of enzymes. The heptamethine dye structure was characterized by various spectroscopic techniques including 1H-NMR, 13C-NMR and high-resolution accurate mass spectroscopy (HRMS). We have also shown the hydrophobicity spectrally by varying methanol/water ratios and observing corresponding absorbance and fluorescence spectral changes.

Highlights

Cyanine dyes are an interesting class of fluorescent compounds that are defined by two terminal heterocyclic nitrogen containing rings that have a delocalized monocation across a polymethine bridge, as compound 4 shown in Scheme 1 [1,2,3,4,5]
Bioanalytical chemists have successfully employed these compounds as non-covalent labels or nucleic acid fluorescent tags [9,10,11]
We have capitalized on optimum optical properties tailored using the chemical structure by designing a NIR-absorbing and fluorescing heptamethine cyanine dye that reports on the hydrophobicity of its environment

Summary

Introduction

Cyanine dyes are an interesting class of fluorescent compounds that are defined by two terminal heterocyclic nitrogen containing rings that have a delocalized monocation across a polymethine bridge, as compound 4 shown in Scheme 1 [1,2,3,4,5]. We have capitalized on optimum optical properties tailored using the chemical structure by designing a NIR-absorbing and fluorescing heptamethine cyanine dye that reports on the hydrophobicity of its environment. It has been reported throughout the literature that hydrophobic cyanines form non-fluorescent blue-shifted dimers (Haggregates) after being placed in highly polar environments (water, PBS/FBS buffers, etc.) [9,10,11,12,13,14].

Results

Conclusion