Near‐Infrared Responsive Conjugated Polymers to 1.5 μm and Beyond: Synthesis and Electrochromic Switching Application

Abstract

Azulene-containing conjugated polymers with near-infrared absorption up to 1.5 μm and beyond are achieved by treating with trifluoroacetic acid (TFA). Density functional theory calculations reveal that the near-infrared absorption arises from a strong intramolecular charge transfer transition on the polymer backbone, and the near-infrared absorption can be tuned by the degree of protonation. Furthermore, TFA treated polymers show a ten-fold enhancement in electrochromic contrast and significantly improved switching stability, suggesting that these polymers are promising candidates for fabrication of the first generation organic near-infrared devices.

Chromophoric materials derived from a natural azulene: syntheses, halochromism and one-photon and two-photon microlithography

“…[3][4][5] Similarly, the physical, electronic, and optical properties of some natural pigments could offer access to key building blocks for developing bio-derived chromophoric materials. [9][10][11][12][13][14][15][16] Chemically, guaiazulene is a nonalternant hydrocarbon that is notable for its low transition energy to the S 1 state and unusually large S 1 -S 2 gap, [17][18][19][20][21][22][23][24][25][26][27] where S 1 and S 2 refer to the first and second electronically excited states, respectively. 3,8 Among known natural pigments, 6-8 guaiazulene has received recent popularity for its interesting physical and electronic properties.…”

“…6-8 Additionally, the non-toxic nature and the accompanying eco-friendly feature of natural dyes could set the stage for chemists to develop "green" routes towards photonic and conductive materials. [17][18][19][20][21][22][23][24][25][26][27] It was shown that extending the conjugation through the seven-membered ring of the parent azulene with aromatic substituents dramatically impacts the optical, electrochemical, and electrochromic properties of the azulenylium carbocation. [9][10][11][12][13][14][15][16][17] As a nontoxic natural product found in the oils of Guajacum officinale and Matricaria chamomilla, as well as in the vibrant-blue mushroom Lactarius indigo, guaiazulene has been approved by the FDA as a cosmetic color additive.…”

“…[9][10][11][12][13][14][15][16][17] As a nontoxic natural product found in the oils of Guajacum officinale and Matricaria chamomilla, as well as in the vibrant-blue mushroom Lactarius indigo, guaiazulene has been approved by the FDA as a cosmetic color additive. [20][21][22] In this work, we describe the use of guaiazulene in the design of a nonerasable 3D fluorescence readout (permanent or write-once read-many, WORM) system, which is comprised of a switch-on fluorescent guaiazulene-containing chromophore and commercially available iodonium photoacid generator (PAG) in thin polymethyl methacrylate (PMMA) film. As a result of its high electron density at C-3, guaiazulene can readily participate in electrophilic aromatic substitution.…”

Carbazole-benzothiadiazole-based conjugated copolymers : synthesis, electrochromism and electrofluorochrochromism

“…135 Wang et al reported azulene-thiophene based CPs that exhibit electrochromism in near IR region (~1500 nm). 136 Azulene can be regarded as an aromatic 6π electron tropylium cation fused by a 6π electron cyclopentadienyl anion. Due to the electron-rich cyclopentadienyl anion, azulene can easily undergo electrophilic substitution at C-1 or C-3 in the 5membered ring and form a very stable aromatic 6π-electron azulenium cation (tropylium cation).…”

“…It is also popularly used in the syntheses of conjugated polymers for EC applications in the recent years. 119,120,135,136,172 Stille coupling, which is another…”