Silicon incorporation in polymethine dyes

Abstract

Incorporation of silicon into heterocycles for polymethine dyes can impart red-shifts of up to 100 nm, while also enhancing photostability up to 10-fold, resulting in photostable fluorophores with emission above 900 nm.

Near-infrared dyes for two-photon absorption in the short-wavelength infrared: strategies towards optical power limiting

“…For instance, it was shown that the conformational restraint within polymethines is helpful to slightly red-shift the absorption while significantly improving the radiative deexcitation rate in heptamethine 37 or julolidinebased cation 38. [144][145][146] Heterocyclic extremities such as azaazulene, 147,148 indolizine, 149 flavylium [150][151][152] or xanthylium 153 were also developed and demonstrated stronger abilities to red-shift the absorption compared to classical indolenium or pyridinium moieties. The flavylium and xanthylium series 39 and 40 show that NIR wavelengths are straightforwardly reached with only a trimethine-long bridge.…”

Counterion Pairing Effects on a Flavylium Heptamethine Dye†

“…This phenomenon occurs predominately in longer chained polymethine dyes (Fig. 1a, n ≥ 3) though there are few instances where large heterocycles can cause a similar effect in shorter vinylogs (30)(31)(32)(33). Counterion identity can play a major role in which these two states dominate (27,34).…”

Flavylium‐ and Silylrhodapolymethines In Excitation Multiplexing

“… Comparison of silylrhodapentamethine and rhodapentamethine dyes (values shown are in dichloromethane) [4] …”

“…The silylrhodapentamethine showed absorbance peaks characteristic of both the silylrhodamine and the polymethine fragments at 663 and 938 nm. The system is solvatochromatic, the lower wavelength absorbance became more prevalent in polar solvents [4] . Dual absorbance peaks and solvatochromaticity are an effect of incomplete resonance between one silylrhodamine and the rest of the dye.…”