ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structure and properties of 2-[(E)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3H-indolium chloride

Martina Lešková, Yaroslav R. Bazel, Marcel Torok, and Yaroslav Studenyak

P. J. Šafárik University, Moyzesova 11, 04154, Košice, Slovakia

E-mail: matka.leskova@gmail.com

Abstract: 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.

Keywords: 2-[(E)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3H-indolium chloride – structure – properties

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-012-0290-8

Chemical Papers 67 (4) 415–422 (2013)