Supramolecular construction of vesicles based on core-substituted naphthalene diimide appended with triethyleneglycol motifs

The self-assembly of core-substituted naphthalene diimides bearing triethylene glycol motifs leads to the formation of stable vesicles in DMSO and CHCl(3)/MeOH (6?:?4, v/v) solvents. The vesicles were evaluated by means of UV/vis and fluorescence spectroscopy, transmission electron microscopy, atomic force microscopy and dynamic light scattering.     

Core-tetrasubstituted naphthalene diimides: synthesis, optical properties, and redox characteristics

2,3,6,7-tetrabromonaphthalene dianhydride has been synthesized by the bromination of naphthalene dianhydride with dibromoisocyanuric acid in excellent yield. The condensation of this dianhydride with 2,6-diisopropylaniline yielded the corresponding tetrabromo-substituted naphthalene diimide (NDI), which is a versatile precursor for the synthesis of core-tetrafunctionalized NDIs. Nucleophilic substitution of tetrabromo NDI with alkoxy, alkylthio, and alkylamino nucleophiles afforded a series of core-tetrasubstituted NDI chromophores that complete the series of previously reported di- and trifunctionalized NDI derivatives. The effects of electronic nature and number of core substituents on the optical and electrochemical properties of NDIs have been investigated by UV-vis and fluorescence spectroscopy and cyclic voltammetry. The absorption maxima (629-642 nm) of tetraamino NDIs are strongly bathochromically shifted compared to those of other core-functionalized NDIs.     

Synthesis and optical properties of triphenylene-based dendritic donor perylene diimide acceptor systems

A donor-acceptor charge transfer system based on two discotic mesogens has been synthesized. The donor is either a triphenylene (POG0) or a triphenylene-based conjugated dendron (POG1), while the acceptor is a perylene diimide (PDI) core. The donors are covalently linked to the bay positions of the PDI core through an ether linkage. In chloroform, due to the short donor-acceptor distance and the matching frontier orbital levels, photoinduced charge transfer from either the donor excitation or the acceptor excitation are both thermodynamically and kinetically favored, resulting in efficient quenching of both donor and acceptor fluorescence. In a less polar solvent, hexane, while charge transfer is still the dominant mechanism for decay of the excited electronic state of POG1, photoinduced charge transfer is no longer energetically favorable for POG0 when the acceptor PDI core is excited, making the PDI core of POG0 weakly fluorescent in chloroform but strongly so in hexane. In solid film, POG0 is highly aggregated through both PDI-PDI and triphenylene-triphenylene homotopic stacking. POG1, on the other hand, aggregates through triphenylene dendrons with limited PDI-PDI core stacking, presumably due to the steric hindrance caused by bulky triphenylene moieties which block the access to the PDI core. The efficient photoinduced charge transfer, coupled with the homotopic stacking that forms separated electron-transporting PDI-stacked columns and hole transporting triphenylene-stacked columns, suggests that the reported donor-acceptor systems based on dual-discotic mesogens are potentially new efficient photovoltaic materials.     

A tetrathiafulvalene-functionalized naphthalene diimide: synthesis, electrochemical and photophysical properties

A tetrathiafulvalene donor has been attached to the naphthalene diimide core via a rigid bridge affording a new planar molecular dyad. Its electronic properties have been studied experimentally by the combination of electrochemistry and UV-vis-NIR spectroscopy. Various electronic excited charge-transfer states are generated in different oxidation states, leading to almost full absorption in the visible to near-IR region with high extinction coefficients. The observed electronic properties are explained on the basis of density-functional-theory. In particular, the oxidized radical species show a strong tendency to undergo aggregation, in which the long-distance attractive interactions overcome the electrostatic repulsions.     

Synthesis and characterization of naphthalene diimide (NDI)-based near infrared chromophores with two-photon absorbing properties

A new series of 2,7-bis-(2-ethylhexyl)-benzo[lmn][3,8]-phenanthroline-1,3,6,8-tetraone (NDI) based pseudo-quadrupolar molecules (1-6) is presented and their two-photon absorption (2PA) cross-sections measured with the Z-scan method. The spectral properties of these compounds can be fine-tuned via modification of the donor segments. The corresponding 2PA cross-section (σ₂) values at the most readily available 800 nm excitation range from 229±15 to 1092±59 GM owing to differences in conjugation length and/or position of substitution.     

Synthesis and characterization of poly(aryl ether imide)s containing electroactive perylene diimide and naphthalene diimide units

The synthesis and polymerization of two new electroactive bisphenols derived from 3,4,9,10‐perylenetetracarboxylic dianhydride and 1,4,5,8‐naphthalenetetracarboxylic dianhydride with 2‐(4‐aminophenyl)‐2‐(4‐hydroxyphenyl)propane, respectively, are described. Copolymerization using the two new bisphenols and 4,4′‐isopropylidenediphenol with bis(4‐fluorophenyl)sulfone and 4,4′‐difluorobenzophenone, afforded a series of soluble electrochromic poly(aryl ether imide)s with glass‐transition temperatures ranging from 160 to 315 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3467–3475, 2000     

Synthesis and optical properties of soluble near-infrared arylene bisthienoimidazole dyes

Soluble, film-forming near-infrared arylene bisthienoimidazole dyes with a band gap of 1.2-1.3 eV are electrochromic and absorb strongly at the telecommunication wavelengths (1310 and 1550 nm) in the oxidized state.     

The impact of vertical π-extension on redox mechanisms of aromatic diimide dyes

The impact of vertical π-extension on redox mechanisms of aromatic diimides in the organic lithium-ion batteries have been carefully studied by a combined experiment and theoretical analyses.     

Synthesis and characterization of optical and redox properties of bithiophene-functionalized diketopyrrolopyrrole chromophores

A series of six new 2,2'-bithiophene-functionalized diketopyrrolopyrrole (DPP) dyes 7a-f bearing different electron-donating and electron-withdrawing substituents at the terminal thiophene units was synthesized by palladium-catalyzed cross-coupling reactions. The to date unknown diiodinated DPP 2 and the corresponding boronic ester derivative 3 could be prepared in high yields, and these are shown to be versatile building blocks for the synthesis of DPP-based molecular materials by Negishi, Stille, and Suzuki coupling. The influence of the peripheral substituents on the optical and electrochemical properties of the present series of DPP dyes 7a-f were investigated by UV/vis and steady-state fluorescence spectroscopy and cyclic voltammetry, revealing an appreciable effect on the electronic nature of these dyes. The diamino-substituted DPP derivative 7e exhibits a strong absorption band reaching in the near-infrared (NIR) region, which is a highly desirable feature for application in organic photovoltaics.     

Photoblinking and photobleaching of rylene diimide dyes

We investigate photoblinking and photobleaching of perylene diimide (PDI) and its higher homologue terrylene diimide (TDI). Single molecule fluorescence trajectories of the dye molecules embedded in PMMA under ambient conditions exhibit "on"-"off" blinking in the time range from ms to s. Due to the limited statistics of individual trajectories we construct ensemble distributions of "on" and "off" times which follow power laws with similar power law coefficients (m(on) ≈ 1.18, m(off) ≈ 1.31). The blinking is attributed to reversible formation of radical cations which are presumably created by electron transfer from higher excited triplet states T(n) of the molecules to acceptor levels in the PMMA host. This view is corroborated by the properties of TDI, which blinks at an excitation wavelength of 520 nm but does not at lower energy excitation (647 nm). In line with this observation, T(1)-T(n) absorption data of TDI (and PDI) indicate that above a certain illumination wavelength population of higher excited triplet states T(n) does not occur, preventing blinking. It is furthermore argued that the long-lived dark ("off") states, i.e. the radical cations, are precursors for the photobleaching process of the dye molecules. Consequently, the photobleaching quantum yield Y(bl) for TDI is very small at an excitation wavelength of 647 nm (Y(bl) = 2 × 10(-10)) but increases by two orders of magnitude at 520 nm (Y(bl) = 2 × 10(-8)), which lies in the range observed for PDI investigated with an excitation wavelength of 488 nm. Additional studies of a PDI-TDI donor-acceptor dyad give further insights into the blinking and bleaching processes. Important findings include the observation of power law blinking of TDI and PDI (after bleaching of TDI) with similar coefficients as found for the isolated chromophores. Furthermore, in the dyad the photostability of TDI decreases due to efficient population of the states T(n) by singlet-triplet annihilation, while that of PDI (after bleaching of TDI) is the same as for the isolated dye. These findings support the conclusions drawn for the isolated chromophores, in particular the involvement of the triplet manifold in the blinking (and bleaching) behavior.     

A comparison of linear optical properties and redox properties in chalcogenopyrylium dyes bearing ortho-substituted aryl substituents and tert-butyl substituents

A series of thiapyrylium pentamethine dyes (4 and 12-15) bearing 2,2'-di-tert-butyl-6,6'-diphenyl, 2,2'-di-tert-butyl-6,6'-bis(2,6-dimethylphenyl), 2,2'-di-tert-butyl-6,6'-bis(2-methylphenyl), 2,2',6,6'-tetrakis(2,6-dimethylphenyl), and 2,2',6,6'-tetrakis(2-methylphenyl) substituents, respectively, were prepared and their linear optical properties and electrochemical redox properties were measured and compared to thiapyrylium pentamethine dyes 3 and 5. The tert-butyl and 2,6-dimethylphenyl substituents give nearly identical chromophores with respect to values of lambda(max), molar extinction coefficients (epsilon), bandwidths at half-height (nu(1/2)), and lack of absorption in the visible spectrum. The 2-methylphenyl substituent imparts linear optical properties that are intermediate between those of the tert-butyl and phenyl substituents. The 2,6-dimethylphenyl and 2-methylphenyl substituents impart greater oxidative stability based on anodic shifts in oxidation potential.     

Stepwise cyanation of naphthalene diimide for n-channel field-effect transistors

Stepwise cyanation of tetrabromonaphthalenediimide (NDI) 1 gave a series of cyanated NDIs 2-5 with the monocyanated NDI 2 and dicyanated NDI 3 isolated. The tri- and tetracyano- NDIs 4 and 5 show intrinsic instability toward moisture because of their extremely low-lying LUMO energy levels. The partially cyanated intermediates can be utilized as air-stable n-type semiconductors with OFET electron mobility up to 0.05 cm(2) V(-1) s(-1).     

Electrical and optical properties of some azo dyes

The dipole moments of six monoazo dyes were obtained from measurements of their static dielectric constants and refractive indices of dilute solutions in benzene and carbon tetrachloride at temperatures between 20°C and 40°C. Also their lightfastness and absorption spectra (λ_max) were measured.From the results obtained, it was found that there is a linear relationship between the dipole moment, lightfastness and maximum absorption (λ_max) of the monoazo dyes under investigation.     

Perylene and naphthalene diimide copolymers for all-polymer solar cells: Effect of perylene/naphthalene ratio

We report the synthesis of a series of copolymers, having 2,2′-bithiophene as electron-donating moiety, and perylene diimide (PDI) and/or naphthalene diimide (NDI) as electron-accepting moiety, and employed as non-fullerene acceptors in polymer solar cells (PSCs). All the copolymers show wide absorption varying from 300 to 850 nm in the visible and NIR spectrum. When changing the PDI/NDI ratio in the polymer backbone, The LUMO energy levels vary in the range of −3.90 to −3.80 eV and the HOMO energy levels vary in the range of −6.10 to −5.85 eV. Among PSCs based on PTB7-Th donor and these polymer acceptors, the devices based on PTB7-Th/NDI100 yield the best power conversion efficiency (PCE) of 4.67%, while the PTB7-Th/PDI100-based devices yield a PCE of 1.03%. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 682–689     

Dimeric naphthalene diimide based small molecule acceptors: synthesis,characterization, and photovoltaic properties

Herein, we present two naphthalene diimide (NDI) dimer based small molecule acceptors, Bis-NDI-T-EG and Bis-NDI-BDT-EG, in which two NDI units are bridged, respectively, by a thiophene (T) or a benzodithiophene (BDT), and further symmetrically substituted by 2-methoxylethoxyl (EG), both through the bay-region. These two NDI dimers exhibit broad absorption in the visible region of 300–650 (800) nm and display a HOMO/LUMO energy level of −5.88 eV/−3.80 eV and −5.46 eV/−3.78 eV, respectively. When PBDTTT-C-T was chosen as the polymer donor, Bis-NDI-T-EG and Bis-NDI-BDT-EG exhibited efficiencies of 1.31% and 1.24%, respectively.     

新型菲并二氧化噻二唑类染料的合成及性能

设计合成了4种以菲并二氧化噻二唑结构为电子受体、三苯胺或N,N-二(4-正丁基苯基)苯胺结构为电子给体的D-A-D型纯有机功能染料5a,5b,6a和6b.利用紫外-可见吸收光谱、荧光发射光谱、循环伏安曲线及理论计算对该染料的光学、电化学性质进行了研究.结果表明,染料5a,5b,6a和6b在可见光区域均有较宽的吸收带,其最大吸收波长分别为581,619,644和671 nm.     

Synthesis and optical properties of new 2-oxo-4-vinyl-2H-chromene-3-carbonitrile dyes

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Studies of third-order optical nonlinearities and optical limiting properties of azo dyes

In order to protect optical sensors and human eyes from debilitating laser effects, the intensity of the incoming laser light has to be opportunely reduced. Here, we report our results on the third-order optical nonlinearity and optical limiting properties of three azo dyes exposed to a 532nm continuous wave laser. We have observed low power optical limiting based on nonlinear refraction in our samples.