Application of Microwave Assisted Organic Synthesis to the Development of Near-IR Cyanine Dye Probes

A Highly Selective Sensor for Cyanide in Organic Media and on Solid Surfaces

“…IR-786 is a commercially available cyanine dye, traded as IR 786 perchlorate (2-(2-[2-chloro-3-([1,3-dihydro-1,3,3-trimethyl-2 H -indol-2-ylidene]ethylidene)-1-cyclohexen-1-yl]ethenyl)-1,3,3-tri-methylindolium perchlorate) with a symmetrical heptamethine bridge ( Scheme 1 ) [ 21 ]. IR-786 possesses useful characteristics to be considered as an anion sensor: absorption spectral near-infra red region, Stokes’ shift (25 nm), large extinction coefficient, high quantum yields [ 16 ] and ability to undergo conjugation with selective anions [ 9 , 22 ]. Therefore, we investigated whether IR-786 can be used as an anion sensor by observing the changes in its color, absorption and emission spectrum before and after the addition of anions (F − , AcO − , CN − , OH − , H 2 PO 4 − , Br − , Cl − , N 3 − , ClO 4 − and HSO 4 − ) in organic media and solvent-free solid surfaces.…”

“…These developments have fueled the development of new NIR dyes with desirable photophysical properties as well as synthesized on a large scale [ 15 , 17 ]. NIR chemical sensors such as IR-786 operate in a longer wavelength range (absorption peak between 700 and 900 nm) [ 21 ], and exhibit minimal background interferences affording for high sensitivity for anions compared to the short wavelength organic sensors [ 17 , 20 , 21 , 22 ]. Moreover, these dyes are relatively inexpensive and can operate in both aqueous and organic media [ 9 , 18 , 19 ].…”

“…, 2-hydroxy-1,4-naphthoquinone or lawsone) was used to detect acetate and cyanide in aqueous media [ 23 ]. However, lawsone operates in the short-wavelength (visible) region, is prone to background interferences and scattering [ 9 ] and therefore is not best suited for biological applications [ 22 , 24 ].…”

Synthesis, crystal structures, and spectral properties of double N-alkylated dimethine cyanine dyes and their interactions with biomolecules and living cells

“…Cyanine dyes, a class of synthetic functional dyes with two heteroaromatic rings joined by a methine chain, are widely used in materials, [1][2][3][4] biomedicine [5][6][7][8] and other elds 9 because of their high extinction coefficients, tunable absorption/emission spectra, and a moderate-to-high uorescence quantum yield. Monomethine cyanine dyes are important in the family of cyanine dyes, and have also been used in the biomedical eld because of their high affinity towards certain biological molecules, 10 such as in nucleic acid detection, [11][12][13] as a protein-based uoromodule, 14 for DNA sequencing [15][16][17] and cell imaging 18,19 and so on.…”

Synthesis of Quaternary Heterocyclic Salts

“…The general procedure for symmetric cyanine dyes involves two equivalents of heterocyclic salt, one equivalent of the bisimine reagent, two equivalents of sodium acetate and solvent, which are added to a reaction vial, sealed and heated in a microwave system [ 20 ]. The ethyl cyanine dye, for example, was synthesized in 79% yield and this was confirmed by 1 H-NMR with the disappearance of the singlet corresponding to the methyl protons of the salt at 2.87 ppm, and the appearance of the doublets of the α- and β- protons of the polymethine bridge at 6.24 ppm and 8.35 ppm, respectively.…”