Anthracene Chromophore Research Articles

Blue light emission of new anthracene derivatives produced using optimized side group link positions

Using an anthracene chromophore as a core group and a phenyl carbazole chromophore as a side group, three new emitters of blue light, 2-DCPA, 3-DCPA and 4-DCPA, were synthesized. The three compounds differed with regard to the position of the carbazole linked to the core, with 2-DCPA and 4-DCPA using carbazole nodes and 3-DCPA using the lobe position. Density functional theory calculations were performed to determine which positions of the carbazole moiety had node characteristics and which had lobe characteristics. The PLmax values of 2-DCPA, 3-DCPA and 4-DCPA in the film state were in the blue region, at 453, 457, and 452 nm, respectively. Of these materials, 3-DCPA, i.e., that with the linkage to the lobe position, showed the highest efficiency, with a value of 2.91 cd/A, and EQE, with a value of 2.65%. In a doped device using CBP as a host material and 3-DCPA as a dopant, the ELmax emission was observed to be in the deep blue region, at 433 nm, and with a CIE value of (0.150, 0.068).

Sensitizer-Free Photon Upconversion in Single-Component Brominated Aromatic Crystals

A new methodology of single-component photon upconversion (UC) based on S0-to-T1 (S−T) absorption is demonstrated. Although the S−T absorption is spin-forbidden, modification of anthracene chromophores with heavy bromine atoms allows the direct population of the excited triplets in crystals upon near-infrared (NIR) excitation with incident light intensities of ∼W cm−2. The consequent triplet energy migration (TEM) and triplet-triplet annihilation (TTA) events in crystals lead to blue UC emission with a large anti-Stokes shift over 0.9 eV. The generality of the S−T absorption-based UC is further confirmed with crystals of brominated perylene-derivatives that show a green UC emission under a longer-wavelength NIR excitation (λex=856 nm). The single-component UC with large anti-Stokes shifts observed for brominated aromatic crystals compensates for the shortcomings of conventional two-component solid UC system, i. e., energy losses intrinsic to the intersystem crossing of the sensitizers and the triplet energy transfer from sensitizer to emitter. It offers a simple and complementary UC methodology to the conventional two-photon absorption (TPA) and TTA-UC.

Halogen Effect on Non-Conventional Organogel Assisted by Balanced π-π Interaction

Triphenylamine-functionalized anthracene derivatives bearing no alkyl chains or amide units (ADIPA and Br-ADIPA) are synthesized in a straightforward manner. Among these two compounds, Br-ADIPA could form stable gel in organic solvents, but ADIPA cannot gelate any conventional solvents under the tested conditions. In order to disclose the supramolecular self-assembly of Br-ADIPA gel, a series of characterizations were performed, which indicated that it might self-assemble into aggregates which do not involve π-π stacking between anthracene chromophore in the gel state, and intermolecular π-π interactions between phenyl rings on triphenylamine moieties are essential driven forces for its gelation. Interestingly, the self-assemblies of these two compounds calculated using Polymorph software well matched the characterization results. It revealed that a one-dimensional molecular packing was promoted by multiple intermolecular π-π interactions between triphenylamine units in Br-ADIPA, and the bromine atom played important role in its balanced intermolecular π-π interactions. In comparison, these supramolecular forces in ADIPA provided a three-dimensional structure.

Fluorophore Release from a Polymethinic Photoremovable Protecting Group Through a Nonlinear Optical Process

AbstractTriggering the release of chemical species through the use of light is crucial for modern microscopy applications, such as single‐molecule localization and, in general, in the regulation of molecular effectors. Herein, we demonstrate a nonlinear‐optical scheme for the control of photorelease. Our system consists of a two‐photon‐absorbing photoremovable protecting group (PPG) bonded to a second chromophore which undergoes photo‐induced detachment and activation upon excitation with λ=850 nm femtosecond pulses. The two‐photon PPG section consists of a cyanine‐type dye, and the releasable section is a highly fluorescent derivatized anthracene chromophore bonded to the cyanine through a photolabile etheric‐meso‐carbon bond. This method allows for the release of a fluorophore following a spatially localized two‐photon excitation event. Both the excitation energy and the long lifetime of the upper excited states of the PPG chromophore are thought to be involved in the release process.

Supramolecular polymerization of hydrogen-bonded rosettes with anthracene chromophores: regioisomeric effect on nanostructures

Regioisomeric introduction of barbituric acid and aliphatic tail units onto anthracene core resulted in distinctly different π–π stacking arrangements upon aggregation in nonpolar solvent, resulting in the formation of supramolecular polymers with either non-helical or helically twisted fibrous morphologies. The difference in the topology of these fibrous nanoaggregates is attributed to the conformational difference of anthracene chromophores with respect to the plane of hydrogen-bonded supermacrocycle.

Syntheses, structures, surface photovoltage and luminescent properties of a novel lead(II) coordination polymer containing anthracene chromophore

A novel 1D lead(II) coordination polymer containing anthracene chromophore through the employment of hydrothermal techniques by using 9-anthracenecarboxylic acid and PbI2, [Pb(9-aca)2(H2O)2] (1) (9-acaH=9-anthracenecarboxylic acid) has been synthesized and structurally characterized by X-ray single-crystal diffraction as well as by powder X-ray diffraction and elemental analysis. In compound 1, each PbO8 polyhedron is linked to each other by oxygen atoms from 9-acaH ligand to form a 1D molecular nanowire with a diameter of 1.22 nm. Surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage (FISPS) of compound 1 indicate that it possesses positive SPV response in the range of 300–800 nm and shows p-type semiconductor characteristic. Luminescent properties of compound 1 reveal that the compound exhibit strong luminescence, ascribed to the charge transfer of anthracene chromophore and the semiconductor 1D Pb2O2 chain.

Molecularly Dispersed Donors in Acceptor Molecular Crystals for Photon Upconversion under Low Excitation Intensity

For real-world applications of photon upconversion based on the triplet-triplet annihilation (TTA-UC), it is imperative to develop solid-state TTA-UC systems that work effectively under low excitation power comparable to solar irradiance. As an approach in this direction, aromatic crystals showing high triplet diffusivity are expected to serve as a useful platform. However, donor molecules inevitably tend to segregate from the host acceptor crystals, and this inhomogeneity results in the disappointing performance of crystalline state TTA-UC. In this work, a series of cast-film-forming acceptors was developed, which provide both regular acceptor alignment and soft domains of alkyl chains that accommodate donor molecules without segregation. A typical triplet sensitizer, PtII octaethylporphyrin (PtOEP), was dispersed in these acceptor crystals without aggregation. As a result, efficient triplet energy transfer from the donor to the acceptor and diffusion of triplet excitons among regularly aligned anthracene chromophores occurred. It resulted in TTA-UC emission at low excitation intensities, comparable to solar irradiance.

Mechanical motion of molecular crystals induced by [4 + 4] photodimerisation

The photomechanical bending of crystals of a stilbene-type compound substituted with anthracene and indanone groups, (E)-2-(9-anthrylmethylene)-1-indanone (trans-1), was investigated. When a narrow plate-like microcrystal was irradiated with ultraviolet (UV) light at 365 nm, the crystal gradually bent away from the light source and finally reached a semicircular shape after more than 10 min. A larger rod-like crystal, approximately 10 mm in length, also exhibited a slight bending motion. The cessation of UV irradiation caused the bent crystals to return very slowly to their straight form. In the crystals, the anthracene planes of two neighbouring trans-1 molecules are arranged in a head-to-tail parallel manner, with a short plane-to-plane distance of only 3.72 A. The 1H nuclear magnetic resonance spectra of trans-1 crystals before and after UV irradiation revealed the intermolecular [4 + 4] photodimerisation of the two anthracene planes, while the trans-to-cis photoisomerisation was not significant. The UV-vis absorption spectra of the trans-1 powder crystals, obtained using a diffuse reflectance spectrophotometer, showed a gradual increase in absorbance between 200 and 500 nm with increasing UV irradiation time, reaching a maximum after 1 h. Thermal back-monomerisation was very slow in the dark, not recovering the initial spectrum even after 25 days. The fluorescence spectra at 570 nm, derived from the anthracene excimer, decreased in intensity with increasing UV irradiation time due to a decrease in the amount of anthracene chromophore via photodimerisation. In situ X-ray measurements revealed that the bending of the crystals was caused by slight elongation of the b axis of the unit cell, corresponding to the long axis of the rod-like crystals. Calculations revealed that the observed crystal elongation could be explained by an optimised head-to-tail [4 + 4] orientation of the anthracene dimer.

Controlled Intramolecular Charge Transfer Using a Sulfur-Containing Acceptor Group

A series of donor–acceptor (D–A) and donor–acceptor–donor (D–A–D) molecules containing anthracene chromophores paired with a sulfur-containing acceptor group have been prepared. The oxidation state of the acceptor sulfur atom controls the degree of charge transfer character in the excited state wave function. Steady-state photoluminescence spectroscopy shows more pronounced solvatochromism with increasing sulfur oxidation state. Computational methods (DFT/TD-DFT) are used to show that orbital mixing between donor and acceptor is facilitated as the oxidation state of the acceptor sulfur is increased.

Anthracene adamantylbisurea receptors: switching of anion binding by photocyclization

Anion binding of adamantane bisurea receptors 1–4 bearing anthracene chromophores was investigated in DMSO solution by UV–vis and fluorescence titrations. All derivatives form stable complexes with F− (K1:2≈105–106 M−2), AcO− (K1:1≈103 M−1), and H2PO4− (K1:1≈103–104 M−1, K1:2≈105–106 M−2). Photochemical reactivity of 1–4 in the [4π+4π] photocyclizations was also investigated. Anthracene 1 is photochemically stable, 3 and 4 undergo reaction giving mixture of products, but 2 reacts selectively yielding only cyclic product 5. Product 5 was isolated and characterized by X-ray analysis. Cyclic receptor 5 also binds anions but forms complexes with different stability constants than its opened analogue 2. Anthracene 2 forms more stable complex with H2PO4−, whereas cyclic receptor 5 forms the most stable complex with AcO− (K1:1 >106 M−1).

Luminescence Properties of Anthracene Chromophores in Cyclosiloxane-Based Hybrid Polymer Films

Luminescence properties of anthracene chromophores were investigated. Anthracene chromophores were incorporated in cyclosiloxane-based hybrid polymers through one-pot hydrosilylation reaction. Using four-armed cyclosiloxanes, divinylterminated siloxane monomers, and 9-vinylanthracenes, anthracene-labeled hybrid polymers were prepared. Free-standing hybrid polymer films were prepared successfully by doctor-blade method and thermal treatment. The polymer films exhibit strong blue fluorescence from anthracene and its fluorescence lifetime was not influenced by the temperature, indicating that the movement of anthracene chromophores was restrained in cyclosiloxane-based hybrid polymer films.

Photophysical characterization of the 9,10-disubstituted anthracene chromophore and its applications in triplet–triplet annihilation photon upconversion

Eight 9,10-disubstituted anthracenes have been synthesized, photochemically characterized and used for triplet–triplet annihilation photon upconversion.

Fluorescent chemodosimeter based on NHC complex for selective recognition of cyanide ions in aqueous medium

Novel N-heterocyclic carbene based mono and di-nuclear silver probes having the anthracene chromophore act as chemodosimeters for selective and sensitive detection of cyanide ions in the aqueous medium and signal the event through visible enhancement in fluorescence intensity.

Photochemical crosslinking of poly-(ethylene–butyl-acrylate) copolymers functionalized with anthracene moieties by reactive extrusion

Anthracene chromophores were successfully bonded onto an ethylene-co-butyl acrylate (EBA) with a content of 19% butyl ester (BA) by transesterification reaction in the molten state using dibutyl tin oxide (DBTO) as catalyst. The modified EBA with covalently attached anthracene moieties (EBA-Ant) were crosslinked by irradiation at 365nm due to face-to-face dimerization in the solid state using films of 10 and 200μm thickness. Also, the anthracene photodimers were cleaved in solid films by irradiating at 280nm. The photoreactions were monitored by UV and fluorescence spectroscopic methods while the mechanical properties of the materials, initial and irradiated, were studied by Dynamic Mechanical Thermal Analysis (DMTA) coupled with measurements of tensile strength and retention of elongation at break.

Synthesis, DNA binding properties and electrochemistry towards an electrode-bound DNA of a novel anthracene–viologen conjugate

We have synthesized herein a novel molecular conjugate integrating an anthracene chromophore and a viologen moiety in the same molecular skeleton, joined together by a p-xylene spacer. This conjugate preserves both the DNA intercalative properties of the anthracene polycycle and the reversible electrochemical behavior of the viologen unit. The simultaneous presence of these components in one single molecular structure increases the affinity towards DNA in solution with respect to that observed for the isolated functional units, probably due to a co-operation of intercalative and electrostatic binding modes. The molecular conjugate interacts with both single and double-stranded DNA absorbed on ITO surfaces. It is shown that the presence of the anthracene unit plays a key role in increasing the affinity for the electrode-bound DNA also for the reduced, monocationic form of the conjugate. The application of the synthesized compound as an electroactive indicator able to discriminate between non-hybridized and hybridized surface-immobilized DNA has been investigated.

Interplay of monomer, intra- and intermolecular excimer fluorescence in cyclophanes and selective recognition of methanol vapours

With an objective to develop simple organic systems for optoelectronic applications, we have investigated photophysical properties of water soluble cyclophane derivatives 1, 2 and model compound 3 in solution and solid state. Of these, the symmetrical cyclophane 1 exhibited monomer emission in methanol, whereas an intramolecular excimer emission was observed in the aqueous medium. Interestingly, in the solid state it showed a highly red-shifted emission maximum when compared to those in the solution. The unsymmetrical cyclophane 2, on the other hand, exhibited monomer emission in both organic and aqueous media, while a dual emission (monomer and excimer) was observed in the solid state. Insights into these unique fluorescence properties were gained by studying the molecular packing of the cyclophanes through single crystal X-ray structure analysis. The cyclophane 1 exhibited a unidirectional sandwich-type packing pattern thereby resulting in strong face-to-face π–π stacking interactions between the anthracene chromophores, whereas 2 exhibited both herringbone and sandwich-type pattern, wherein the interacting anthracene moieties are arranged in an intermolecular T-shaped fashion. By virtue of different molecular packing the cyclophane 1 showed visible fluorescence colour change from yellow to blue when exposed to methanol vapours as compared to ethanol, acetonitrile, hexane and water vapours. Uniquely, this system can detect as low as 1% of methanol in ethanol solution thereby demonstrating its usefulness as an optical probe for the detection of methanol vapours.

Synthesis and DNA interaction of ethylenediamine platinum(II) complexes linked to DNA intercalants

A series of ethylenediamine platinum(II) complexes connected through semi-rigid chains of 1,2-bis(4-pyridyl)ethane to DNA intercalating subunits (naphthalene, anthracene or phenazine) has been synthesized, and their interactions with calf thymus (CT) DNA have been evaluated by viscometric titrations and equilibrium dialysis experiments. The parent ligands that contain anthracene or phenazine chromophores showed a monointercalative mode of DNA interaction (especially the anthracene derivative), with apparent association constants in the order of 104M−1. The corresponding platinum(II) complexes bind CT DNA through bisintercalation, as established by the significant increase of DNA contour length inferred from viscosity measurements, and the association constants are in the order of 105M−1. The naphthalene derivatives, however, exhibit a mixed mode of interaction, which suggests a partial contribution of both intercalation and groove binding for the ligand, and monointercalation in the case of the platinum(II) complex. Competition dialysis experiments carried out on the intercalative compounds have revealed a moderate selectivity towards GC DNA sequences for the derivatives containing the anthracene chromophore.

Hydrogen‐Bonding‐Induced One‐Handed Helical Polynorbornenes Appended With Chiral Alaninegland

AbstractPolynorbornenes appended with anthracene and chiral alanine linkers are synthesized. Hydrogen bonding between the adjacent bisamidic linkers brings adjacent anthracene chromophores in a more suitable orientation for exciton coupling and renders one‐handed helical structures for these polymers. Excimer formation is observed from their emission spectra. Monoamidic linkers provide only one hydrogen bond, which would be less robust and result in much lower circular dichroic response.

Low Molecular Weight Fluorescent Organogel for Fluoride Ion Detection

The design, synthesis, and the photophysical properties of a Low Molecular Weight Gel (LMWG) based on AB(3) and AB(2) type poly(aryl ether) dendrons with an anthracene chromophore attached through an acylhydrazone linkage are described. The gel is utilized for an efficient 'naked eye' detection of fluoride ions (as low as 0.1 equiv with respect to the gelator concentration), through a reversible gel-sol transition, which is associated with a color change from deep yellow to bright red.

Fabrication of layered double hydroxide/photoresponsive dendron nanocomposite multilayer film by electrostatic layer-by-layer assembly

A novel inorganic–organic nanoscopic multilayer film consisting of exfoliated MgAl-type layered double hydroxide (LDH) nanosheets and anthryl dendrons [i.e., poly(amidoamine) dendrons with an anthracene chromophore group at the focal point] was fabricated using an electrostatic layer-by-layer (LbL) assembly. UV–vis spectroscopy and X-ray diffraction analysis indicated the successful LbL growth of dendron/LDH multilayer films. Furthermore, fluorescence spectroscopic analysis indicated that the dendrons are present as a monolayer between LDH nanosheets in the film.