Anthraquinone Imide Research Articles

A Star-Shaped Molecule with Low-Lying Lowest Unoccupied Molecular Orbital Level, n-Type Panchromatic Electrochromism, and Long-Term Stability.

An electron-deficient star-shaped molecule based on anthraquinone imide was synthesized and characterized. It showed high electron accommodating capacity and strong electron-withdrawing ability with a low-lying lowest unoccupied molecular orbital (LUMO) of -4.10 eV. In addition, it exhibited panchromatic electrochromism attributed to the simultaneous presence of π*-π* transitions and intervalence charge transfer (IV-CT) upon one-electron reduction, and revealed long-term stability in electron gain and loss due to the proper LUMO energy level and ordered intermolecular assembly.

Design,Synthesis and Their Application in Photodetectors of Conjugated Polymers Based on Anthraquinone Imide

Design,Synthesis and Their Application in Photodetectors of Conjugated Polymers Based on Anthraquinone Imide

Colorless to Purple–Red Switching Electrochromic Anthraquinone Imides with Broad Visible/Near‐IR Absorptions in the Radical Anion State: Simulation‐Aided Molecular Design

The large redshift of near-infrared (NIR) absorptions of nitro-substituted anthraquinone imide (Nitro-AQI) radical anions, relative to other AQI derivatives, is rationalized based on quantum chemical calculations. Calculations reveal that the delocalization effects of electronegative substitution in the radical anion states is dramatically enhanced, thus leading to a significant decrease in the HOMO-LUMO band gap in the radical anion states. Based on this understanding, an AQI derivative with an even stronger electron-withdrawing dicyanovinyl (di-CN) substituent was designed and prepared. The resulting molecule, di-CN-AQI, displays no absorption in the Vis/NIR region in the neutral state, but absorbs intensively in the range of λ=700-1000 (λmax ≈860 nm) and λ=1100-1800 nm (λmax ≈1400 nm) upon one-electron reduction; this is accompanied by a transition from a highly transmissive colorless solution to one that is purple-red. The relationship between calculated radical anionic HOMO-LUMO gaps and the electron-withdrawing capacity of the substituents is also determined by employing Hammett parameter, which could serve as a theoretical tool for further molecular design.

Near-infrared and multicolored electrochromism of solution processable triphenylamine-anthraquinone imide hybrid systems

A series of novel donor-acceptor molecules (TPA-AQI, TPA-AQI2 and TPA-AQI3) with various number of electron-accepting anthraquinone imide (AQI) arms connected to the electron-donating triphenylamine (TPA) core were synthesized and characterized by UV–vis absorption spectroscopy, cyclic voltammetry and spectroelectrochemical measurements. The geometries of these molecules in ground-state as well as the electronic absorption properties on the basis of the optimized geometries were investigated by theoretical calculations. For all the three molecules, there are two main absorptions in the range of 300–450nm and 450–700nm, respectively. The former corresponds to ππ* transitions and the latter a nature of intramolecular charge transfer (ICT). Hypsochromic shift of the ICT absorption was observed from the single armed molecule TPA-AQI to the tribranched molecule TPA-AQI3, which may result from the increased steric hindrance between the donor and acceptor segments. Electrochemical studies revealed the ambipolar properties of these molecules and three redox couples, with two quasi-reversible redox couples appearing in the cathodic regime and one redox couple in the anodic regime, on CV curves. CV results also indicated the stabilization of the HOMO levels by increasing AQI arms. Spectroelectrochemical measurements demonstrated the near-infrared (NIR) and multicolor electrochromism of these molecules. When reduced to radical anions or oxidized to radical cations, intense NIR absorptions were observed accompanied with color changes of the solutions. As for TPA-AQI, there existed four different colors at different redox states: Indian-red at the neutral state, bluish green at the radical cationic state, olive green at the radical anionic state, and dark blue at the dianion state. The detailed transitions of the observed NIR absorptions were also discussed.

Design and Synthesis of Piezochromic Materials Based on Push–Pull Chromophores: A Mechanistic Perspective

Computational analysis predicts that intramolecular charge transfer (ICT) exists in anthraquinone imide (AQI) derivatives with electron-donating substituents at the 6-position, such as 4-methoxylphenyl, 4-N,N-dimethylaminophenyl, and thiophene. However, for those with electron-withdrawing ones, no clear ICT interaction could be observed. We predicted, on the basis of the simulation results, that AQI derivatives with electron-donating substituents would be piezochromic. To verify this hypothesis, the corresponding AQI derivatives with various substituents were synthesized. Absorption spectra recorded with a diffuse reflectance method on powders revealed that 4-methoxylphenyl-, 4-N,N-dimethylaminophenyl-, and thiophene-substituted AQI exhibited piezochromism, but not 4-nitrophenyl-substituted AQI, which is in good agreement with the simulation results. Interestingly, redshifts of both the lower and higher energy absorption bands were observed along with redshifts of the emission spectra. However, XRD patterns before and after being pressed presented no significant changes, which was different from known piezochromic molecules described in the literature. An unprecedented mechanism in which enhanced ICT from better conjugation between the donor and acceptor segments induced by the decrease of θ under pressure could be responsible for the piezochromism of aryl-substituted AQIs is proposed.

Visible and near-infrared chiroptical gels containing electrochromic anthraquinone imide groups

A cholesterol-based organogelator bearing an anthraquinone imide (AQI) group was synthesized and characterized. It self-assembled into chiral gels in acetonitrile at low concentrations, which displayed a combination of electrochromic and chiroptical properties. Upon electrochemical reduction at −700 mV, the gel exhibited new absorption bands at around 820 nm corresponding to π*-π* (SOMO→LUMO) transitions of the radical anion of AQI and strong negative Cotton effects in the same spectral region. With further reduction at −1000 mV, a new CD band with a negative Cotton effect in the range from 500 nm to 800 nm appeared concomitant with the variation of absorption spectrum. Thus, with the use of electrochromic AQI chromophore as a switch-responsive unit and the stable gel of compound N-[3β-cholest-5-en-3-yl N-(2-aminoethyl) carbamate] anthraquinone-2,3-dicarboxylic imide as a chiral scaffold, a redox-triggered chiroptical switch operating in visible and near-infrared region was realized.

Anthraquinone‐Imide‐Based Dimers: Synthesis, Piezochromism, Liquid Crystalline and Near‐Infrared Electrochromic Properties

AbstractA series of anthraquinone‐imide‐based dimers, C5*‐AQI‐Si2, C5*‐AQI‐Si3, C5*‐AQI‐Si4, and C5*‐AQI‐Si8, have been prepared by the hydrosilylation of N‐(hex‐5‐enyl)‐6‐(4′‐((S)‐2‐methylbutoxy)phenyl)anthraquinone‐2,3‐dicarboxylic imide and hydride‐terminated siloxanes with different lengths. Their liquid crystalline behaviors, and piezochromic and near‐infrared electrochromic properties have been characterized by DSC, wide‐angle X‐ray diffraction, cyclic voltammetry, and UV–vis–NIR spectroscopy. Although anthraquinone imide is not liquid crystalline by itself, all the dimers formed a smectic A mesophase. Under moderate pressure, the color of the dimers changed from light yellow to deep red. Upon reduction to a radical anionic state, the dimers exhibited an intense NIR absorption at 844 nm. These anthraquinone‐imide‐based dimers are probably the first multifunctional molecules with combined liquid crystalline, mechanochromic, and NIR electrochromic properties.magnified image

Near-infrared electrochromic and chiroptical switching polymers: synthesis and characterization of helical poly(N-propargylamides) carrying anthraquinone imide moieties in side chains

Optically active poly(N-propargylamides) containing chiral anthraquinone imide (AQI) side groups have been synthesized. The chiroptical and electrochromic properties of the polymers are investigated. The polymers exhibit intense Cotton effects in the absorption regions of both main- and side-chains, strongly suggesting a helical conformation of the polymer backbone and a skewed packing of pendant chromophores. Additionally, the polymers show two reversible redox states (radical anion and dianion). Intense circular dichroism (CD) signals centered at 780 nm and 530 nm are assigned to the radical anion and dianion intermediates, respectively. The voltage-controlled reversible Cotton effects demonstrate the newly synthesized AQI-containing poly(N-propargylamides) as potential electrochemically driven chiroptical switching materials that operate in the near-infrared wavelength region.

Synthesis, Electrochemistry, and Hydrolysis of Anthraquinone Derivatives

Anthraquinone (AQ) derivatives, including members of the anthraquinone imide (AQI) family, have been synthesized to afford good candidates for electron-transfer studies in DNA. Electron-withdrawing groups on the AQ ring give a less negative reduction potential, as desired. As expected, the AQI derivatives have less negative reduction potentials than AQ derivatives. The AQI ring system has a half-life for hydrolysis of about 75 min in a 3:7 MeCN and 0.005 M K2CO3 in MeOH.

Synthesis and voltage-controlled multicolor electroluminescent property of copolyfluorenes containing a pendent anthraquinone-2,3-dicarboxylic imide

A new series of four fluorene-thiophene copolymers, PF-co-2%TAQI, PF-co-5%TAQI, PF-co-10%TAQI and PF-co-15%TAQI, were synthesized by the Suzuki cross-coupling polymerization of 9,9-dihexylfluorene-2,7-dibromofluorene and N-butyl 6-[3-(2,5-dibromothienyl)]anthraquinone-2,3-dicarboxylic imide. The polymers have good solubility in common organic solvents and can form thin films by spin coating or casting. The UV–vis and photoluminescence (PL) spectra for the copolymers in dilute solution are similar to those of polyfluorene, i.e. maximum absorption at 381 nm and 417 nm and PL at 439 nm. The UV–vis spectra of the polymer films also exhibit a single peak at 378 nm, while an extra emission peak was found at 612 nm, 618 nm, 628 nm and 626 nm for PF-co-2%TAQI, PF-co-5%TAQI, PF-co-10%TAQI and PF-co-15%TAQI, respectively, presumably resulting from the excimer of anthraquinone imide groups. The electroluminescent properties of the copolymers were investigated using single-layer (ITO/PEDOT/Polymer/LiF/Al) and double-layer (ITO/PEDOT/Polymer/TPBi/LiF/Al) (TPBi, 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene) LED devices. The double-layer devices based on copolymers emit multicolors under different voltages. The Commission Internationale de l’Eclairage (CIE) coordinates of PF-co-2%TAQI are (0.356, 0.249), (0.285, 0.210), (0.264, 0.277) and (0.240, 0.250) under 12 V, 14 V, 16 V and 18 V, respectively.

Synthesis and characterization of a novel kind of near-infrared electrochromic polymers containing an anthraquinone imide group and ionic moieties

A novel near-infrared (NIR) electrochromic polyelectrolyte consisting of anthraquinone imide (AQI) pendants and a poly(1-vinylimidazole bromide) main chain was synthesized viaradical polymerization. Its AQI content was varied by copolymerization with 1-vinyl-3-butylimidazole bromide to improve the processability of the polymer as well as the monomer conversion. The electrochemical and electrochromic properties of both homopolymer and copolymers were investigated. All the (co)polymers exhibited two reversible redox states (radical anions and dianions). Spectroelectrochemical analysis in solution showed that the radical anions possessed intense NIR absorptions with λmax values in the range 820 to 830 nm, while the dianions exhibited absorptions between 460 and 560 nm. The homopolymer film displayed an optical attenuation of 3 dB/µm at 810 nm with a switching time of 20 s. Such a polymer can change color in a single film device without any additional electrolytes and showed a rapid response time of 1 s at 810 nm.

Peptide nucleic acid-anthraquinone conjugates: strand invasion and photoinduced cleavage of duplex DNA.

A bis-peptide nucleic acid (PNA)-anthraquinone imide (AQI) conjugate has been synthesized and shown to form strand invasion complexes with a duplex DNA target. The two arms of the bis-PNA each consist of five consecutive thymine residues and are linked by a flexible, hydrophilic spacer. Probing with potassium permanganate reveals that the bis-PNA complexes to duplex DNA at A5.T5sites with local displacement of the T5DNA strand. The 5 bp sequence targeted by the PNA is the shortest strand invasion complex reported to date. Irradiation of the strand invasion complex results in asymmetric cleavage of the displaced strand, with more efficient cleavage at the 3'-end of the loop. This result indicates that the bis-PNA binds to the DNA such that the C-terminal T5sequence forms the strand invasion complex, leaving the N-terminal T5sequence to bind by triplex formation, thereby placing the AQI closer to the 3'-end of the displaced strand, consistent with the observed photocleavage pattern. The ability of the PNA to directly report its binding site by photoinduced cleavage could have significant utility in mapping the secondary and tertiary structure of nucleic acids.