structure and properties of 2-[(e)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3h-indolium chloride

 

the structure of styryl dye, 2-[(e)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3h-indolium chloride (i), was investigated using methods such as uv-vis, fluorescence spectroscopy, and nmr (1h, 13c, apt, hmqc, cosy) and also by examining its electrochemical properties. a study of the acid-base properties revealed the existence of three different forms of the dye. the mechanisms of protolysis and hydrolysis are discussed. the reagent exists in a reactive single-charged form i + over a wide range of acidity (ph 4–11). the optimum analytical wavelength of the singlecharged form is 550 nm, where the molar absorptivity is 5.51 × 104 l mol−1 cm−1. the values of the optimum analytical wavelength and molar absorptivity of the protolysed and hydrolysed forms are: λ max(i-h2+) = 380 nm, ɛ(i-h2+) = 2.01 × 104 l mol−1 cm−1; λ max(i-oh) = 320 nm, ɛ(i-oh) = 1.12 × 104 l mol−1 cm−1. a theoretical study of the spectral and chemical properties of i was carried out by performing quantum chemical calculations.