Synthesis And Properties Of Functional Alkynyl Aromatic Aminecompounds With D-D-A Structure

Aromatic amine compounds carbazole (CZ), triphenylamine (TA) and phenothiazine (PTZ) are the important groups in the design of functional dyes. In order to improve the electron donating ability and the molecular absorption in the visible region, using CZ-CZ, TA-CZ, CZ-PTZ and TA-PTZ as double electron donors, novel D-D-A dyes were designed and synthesized in this paper. Study of their photophysical and photochemical properties and the application as photosensitizer in the photopolymerization were carried out.The synthesized D-D-A dyes were N-ethyl-6-((carbazole-3') ethynyl)-carbazole-3-aldehyde (CZ-CZ-CHO), N-ethyl-6-((carbazole-3') ethynyl)-phenothiazine-3-aldehyde (CZ-PTZ-CHO), N-ethyl-6-((triphenylamine-4')ethynyl)-carbazole-3- aldehyde (TA-CZ-CHO), N-ethyl-6-((triphenylamine-4')ethynyl)-phenothiazine-3-aldehyde (TA-PTZ-CHO) respectively, were synthesized via Sonogashira coupling reaction of 3-ethynylcarbazole,4-ethynyltriphenylamine with3-bromo-9-ethylcarbazole-6-carboxaldehyde,7-bromo-10-ethyl-10H-phenothiazine-3-carboxaldehyde,2-cyano-3-(9-ethyl-6-((9-ethyl-9H-carbazol-3-yl)ethynyl)-9H-carbazol-3-yl)acrylic acid (CZ-CZ-CN),2-cyano-3-(10-ethyl-7-((9-ethyl-9H-carbazol-3-yl)ethynyl)-10H-phenothiazin-3-yl)acrylic acid (CZ-PTZ-CHO), 2-cyano-3-(6-((4-(diphenylamino)phenyl)ethynyl)-9-ethyl-9H-carbazol-3-yl) acrylic acid (CZ-CZ-CHO) and 2-cyano-3-(7-((4-(diphenylamino)phenyl)ethynyl)-10-ethyl-10H-phenothi azin-3-yl)acrylic acid (TA-PTZ-CN). All products were characterized by IR,'H NMR and 13C NMR. Their structures were optimized through the quantum chemistry calculation and molecular frontier orbital analysis.The physical properties were studied via UV-vis absorption spectroscopy, fluorescence spectroscopy.The dyes exhibit the obvious charge transfer character in the ground and excited states and show strong absorption from 380-550nm.One-photon fluorescence spectra indicated that the fluorescence emission wavelengths were between 380nm-700nm. They had large fluorescence quantum efficiency.Ring-opening cationic polymerization of epoxides and free radical polymerization of acrylates upon exposure to irradiation of laser diodes at 455 nm and 532 nm were performed using dyes with iodonium salt (ONI) initiating systems. The combinations of the obtained dyes with iodonium salt exhibit high polymerization efficiency. The highest polymerization efficiency was CZ-PTZ-CHO/ONI under the laser diode of 455nm. The highest polymerization efficiency was CZ-PTZ-CN/ONI under the laser diode of 532nm.Electron-transfer photosensitization mechanism was found by steady state photolysis experiments, theoretical calculation of molecular orbitals, and electrochemistry. Owing to their higher polymerization efficiency, these dyes would have extensive application prospects in the fields of photopolymerization by soft visible light irradiation sources.