Chromophore Moieties Research Articles

High‐Performance Solution Processable Single‐Emitting‐Layer White Circularly Polarized Electroluminescence

AbstractAchieving efficient circularly polarized white organic light‐emitting diode (CP‐WOLED) remains a significant challenge. In this study, a proof‐of‐concept for realizing CP‐WOLED is proposed using an electroplex emission strategy between a chiral thermally activated delayed fluorescence (TADF) emitter and hole‐transporting material. A series of chiral polymers (R/S)‐E‐x (x = 0.02, 0.05, and 0.1) are designed and prepared via random copolymerization of a chiral chromophore and styrene moiety, which shows typical TADF character. The neat film of (R/S)‐E‐0.1 presents distinct chiroptical properties with a dissymmetry factor (|glum|) of 2.8 × 10−3. Notably, solution‐processable, single‐emitting‐layer CP‐WOLEDs are fabricated using these chiral polymers in combination with 1,1‐bis[(di‐4‐tolylamino)phenyl]cyclohexane (TAPC) as the emitter, achieving a record maximum external quantum efficiency of 15.1% and Commission Internationale de lʹeclairage coordinate of (0.36, 0.40). Importantly, these CP‐WOLEDs exhibit an impressive |gEL| value of 2.4 × 10−3. This research provides a straightforward and effective strategy for the realization of high‐performance CP‐WOLED.

Multifunctional Temperature-Sensitive Lipid-Protein-Polymer Conjugates: Tailored Drug Delivery and Bioimaging.

In this study, we introduce a protein-polymer bioconjugate comprising bovine serum albumin (BSA) and a lipid-based thermoresponsive block copolymer. These amphiphilic BSA-polymer conjugates can autonomously be organized into vesicular compartments for codelivery of glucose oxidase (GOx) and doxorubicin (DOX), demonstrating high drug loading content and remarkable antitumor activity via synergistic cancer therapy combining chemo-starvation strategies. Through the incorporation of a hydrophilic BSA block, the lower critical solution temperature (LCST) of the bioconjugates is tuned to around 40 °C, facilitating their targeted drug delivery to tumor cells. Consequently, these smart protein-polymer conjugates present greater promise compared to traditional drug delivery vehicles, particularly in the realm of anticancer therapy. Moreover, these bioconjugates displayed enhanced intracellular fluorescence intensity with increasing temperature, attributed to the clustering-triggered emission of the nonconventional chromophore moieties within poly(vinylcaprolactam) (PNVCL). The active aggregation-induced emission (AIE) characteristic and excellent biocompatibility suggest an opportunity to further apply these bioconjugates for biosensing and cellular imaging.

Unravelling the intricacies of fluorescence enhancement in heptamethine cyanine dyes induced by heavy halogen atoms

The classic heavy-atom effect refers to the photophysical phenomenon observed in fluorophores, where the interaction with heavy atoms quenches fluorescence emission. Many fluorophores containing heavy halogen atoms, such as xanthenes, BODIPYs, porphyrins, and anthracenes, adhere to this effect, while the photophysical behavior of others, e.g. halogenated heptamethine cyanine dyes, is poorly studied having contradicting results. In this study, we explored for the first time unexpected fluorescence enhancement induced by heavy halogen atoms in heptamethine dyes, contrasting the classic heavy-atom effect. To this end, a series of novel heptamethine cyanine dyes were synthesized and their photophysical properties were experimentally and theoretically investigated. Heavy halogen atoms were found to significantly affect the fluorescence behaviour of heptamethine dyes depending on the number and position of the attached halogens. Thus, the introduction of bromine and iodine atoms at the non-conjugated positions to the chromophore moieties led to an increase in the fluorescence quantum yields, which contradicts the classic principle and could be explained by heavy halogen-induced vibration restrictions. The value of halogen atom-promoted singlet oxygen generation quantum yield ΦΔ is also not straightforward and depends on the number, position and weight of the halogen atom. The breaking of the classic heavy-atom effect in halogenated heptamethine dyes provides an effective strategy to substantially increase the fluorescence intensity of long-wavelength cyanine dyes, providing new functional advantages for fluorescence imaging, diagnostics, and photodynamic therapy, among other applications.

Symmetry-Engineered BINOL-Based Porous Aromatic Frameworks for H2O2 Production via Artificial Photosynthesis and In Situ Degradation of Pharmaceutical Pollutants.

Accomplishing visible light-driven H2O2 production at millimolar concentrations is practically challenging, particularly for organic semiconductors. In this context, achieving a maximum H2O2 production rate of 31.60 mmol·g-1·h-1 by using porous aromatic frameworks (PAFs) represents a significant accomplishment. We report the unusual photoactivity of tetraphenylmethane-BINOL-linked PAFs in triplet oxygen activation to facilitate the generation of reactive oxygen species (ROS), as confirmed by their optical and electrochemical responses, despite the absence of a conventional chromophoric moiety. Moreover, an in situ BINOL formation strategy was used to synthesize these PAFs during polymerization in contrast to the reported protocols involving chiral BINOLs as precursors. The as-synthesized polymers had a capsule-like morphology (for TPM-BINOL-6), high thermal stability up to 348 °C, and a high Brunauer-Emmett-Teller (BET) surface area of up to 1382 m2/g (for TPM-BINOL-4). Interestingly, they showed sunlight-driven production of H2O2 via an oxygen reduction reaction of up to 17.05 mmol·g-1·h-1 in 1:10 isopropanol in water for TPM-BINOL-6, which was quantified by titration with ceric sulfate. It also exhibited exemplary photocatalytic efficiency with an H2O2 production rate of 6.65 mmol·g-1·h-1 in seawater. Interestingly, the H2O2 production rate reached a maximum of 18.03 mmol·g-1·h-1 with an SCC efficiency of 4.5% under an AM 1.5G solar simulator and apparent quantum yield (AQY) of 15.8% (at λ = 456 nm) for TPM-BINOL-6 in ethanol:water = 1:10. Moreover, the exceptionally high H2O2 production rate of 31.60 mmol·g-1·h-1 was achieved in 1:1 ethanol in water under 50 W blue LED light. Furthermore, these PAFs generated adequate ROS, which were utilized in the photocatalytic degradation of tetracycline via the superoxide intermediate. Additionally, the as-formed H2O2 was further channelized in the pollution abatement catalytic system for the fast degradation of ciprofloxacin (within 4 h) and the reduction of toxic oxometallate Cr(VI) within 10 min, which is one of the earliest reports of utilizing photosynthesized H2O2 for environmental detoxification.

GFP chromophore derived amphiphiles containing [12]aneN3 and biotin moieties as bio-imaging and targeting nonviral gene vectors

Gene therapy is a promising treatment, that brings the necessary opportunity to cure human genetic and major diseases, but it is hampered by the lack of safe and efficient gene delivery vectors. In this study, four amphiphiles were derived from GFP chromophore benzylimidazolidinone (G) through modifications with oxypropyl (1) or methylene (2) linked di(triazole-[12]aneN3) (M) in the presence or absence of tumor-targeting biotin (B) moiety, GMB-1/2 and GM-1/2. The four compounds showed excellent aggregation-induced emission (AIE) characteristics, strong DNA condensation abilities, and good biocompatibility. Among them, GMB-1, which containing targeting biotin moiety and a flexible propoxy linker, showed the highest transfection efficiency in three cell lines. The luciferase transfection efficiency of GMB-1 was as high as 15.2 times that of Lipofectamine 2000 (Lipo2000) without auxiliary lipid DOPE, and its gene therapy effect of delivering the p53 gene was also significantly better than that of Lipo2000 in HeLa cells due to its obvious targeting property. Fluorescence tracing experiments indicated that GMB-1 was able to quickly carry DNA into cells, to successfully escape from lysosomes, then to release DNA, and at last to smoothly deliver DNA into the nucleus. Moreover, its EGFP transfection efficiency in zebrafish reached 1.7 times that of Lipo2000. The excellent performance of GMB-1 demonstrated that the appreciative incorporation of GFP chromophore, di(triazole-[12]aneN3), and biotin moieties into the nonviral gene vectors provided a promising strategy for their clinical applications.

Total substitution and partial modification of the set of non-ribosomal peptide synthetases clusters lead to pyoverdine diversity in the Pseudomonas fluorescens complex.

Pyoverdines are high affinity siderophores produced by most Pseudomonas with a wide role in microbial interspecies interactions. They are primarily composed of a conserved chromophore moiety, an acyl side chain and a peptide backbone which may be highly variable among strains. Upon ferric iron sequestration, pyoverdines are internalized through specialized receptors. The peptide precursor of pyoverdine, termed ferribactin, is synthesized by a set of non-ribosomal peptide synthetase (NRPS) enzymes and further modified by tailoring enzymes. While PvdL, the NRPS responsible for the synthesis of the peptide moiety that derives into the chromophore is conserved, the NRPSs for the peptide backbone are different across fluorescent Pseudomonas. Although the variation of pyoverdine is a widely recognized characteristic within the genus, the evolutionary events associated with the diversity and distribution of this trait remain mostly unknown. This study analyzed the NRPSs clusters for the biosynthesis of the peptide backbone of ferribactin in the genomes of a representative subset of strains of the Pseudomonas fluorescens complex. Bioinformatic analysis of the specificity of adenylation domains of the NRPSs allowed the prediction of 30 different pyoverdine variants. Phylogenetic reconstruction and mapping of the NRPS clusters pinpointed two different general levels of modifications. In the first level, a complete replacement of the set of NRPRs by horizontal transfer occurs. In the second level, the original set of NRPSs is modified through different mechanisms, including partial substitution of the NRPS genes by horizontal transfer, adenylation domain specificity change or NRPS accessory domain gain/loss.

High Second-Order Nonlinear Optical Effect Achieved by Gradually Decreased Rotational Energy Barriers

With the aim to efficiently convert the microscopic second-order nonlinear optical (NLO) effect of chromophore moieties into a high macroscopic NLO performance as large as possible, this work focused on...

Development of setups for real-time analysis of the effluent of a microreactor by mass spectrometry.

Monitoring a synthesis reaction in real timecould allow not only the detection of the intermediates involved in the synthesis, to better understand its mechanisms, but also the impurities. Spectroscopic methods could be performed but are not so performant when analyzing complex mixtures and could require specific properties for the detection of the molecules of interest, the presence of a chromophore moiety for example. Mass spectrometry (MS) may overcome these limitations and is able to reach the accuracy and sensitivity required to efficiently detect, quantify, identify, and characterize the reagents and species produced during the synthesis. This is why the hyphenation of a microreactor with MS has already allowed synthesis processesto be monitored, but most of the time ittargets a specific reaction or compounds and involves solvents compatible with MS. In this study, a universal setup for thehyphenation ofa microreactor with MS and based on two valves has been developed. This two-valve setup has proven itself for the analysis of molecules of different nature and hydrophilicity, soluble in a large number of solvents even in non-MS-compatible ones. The developed setup evidenced a good repeatability and a linear response for the detection of the studied compounds. In addition, the dilution step included in the two-valve setup allows theMS monitoring of compounds initially synthesized at different concentrations. Finally, it was successfully used to study an amination reaction allowing the detection of the reaction products in 4min with good repeatability as RSD values of MS signals were lower than 17%.

Development of a liquid chromatographic method for enantioseparation of Eflornithine using (S)-α-ethyl benzylamine as a chiral derivatizing agent

ABSTRACT Eflornithine (2-fluoromethyl-DL-ornithine) is a potent and irreversible inhibitor that selectively targets ornithine decarboxylase, a key enzyme in the polyamine biosynthesis pathway. Due to the lack of chromophoric moiety in the eflornithine structure, its detection via UV detector is difficult. Thus, direct high-performance liquid chromatographic (HPLC) separation of enantiomers of Eflornithine is not feasible, and pre-column derivatization is required for its determination through chiral HPLC columns. We developed an indirect HPLC method using (S)-α-ethyl benzylamine as a chiral derivatizing agent for the enantioseparation of Eflornithine. The diastereomers thus produced were then separated via LiChrospher C18 column (5 μm particle size, L × I. D. 25 cm × 4.6 mm). The mobile phase used was a mixture of acetonitrile and 0.1% aq. TFA and varied in linear gradients of 30–70% of acetonitrile for 30 min run at a flow rate of 1.0 mL min−1 and UV detection at 320 nm. The separation parameters were optimized by altering the mobile phase composition and flow rate. The findings revealed that the chromatographic separation was accomplished within 15 min, with resolution values greater than 4.5 for Eflornithine enantiomers. The detection and quantitation limits were 9.26 ng mL− 1 and 18.52 ng mL− 1 for Eflornithine enantiomers.

Oxygen-induced chromophore degradation in the photoswitchable red fluorescent protein rsCherry

Reversibly switchable monomeric Cherry (rsCherry) is a photoswitchable variant of the red fluorescent protein mCherry. We report that this protein gradually and irreversibly loses its red fluorescence in the dark over a period of months at 4 °C and a few days at 37 °C. We also find that its ancestor, mCherry, undergoes a similar fluorescence loss but at a slower rate. X-ray crystallography and mass spectrometry reveal that this is caused by the cleavage of the p-hydroxyphenyl ring from the chromophore and the formation of two novel types of cyclic structures at the remaining chromophore moiety. Overall, our work sheds light on a new process occurring within fluorescent proteins, further adding to the chemical diversity and versatility of these molecules.

Planning and projecting of a green isoindole-based fluoro-probe for feasible tagging and tracking of topiramate, a non-fluorescent drug in bulk powder and prescribed commercial products

Fluorescent probes have supplanted more conventional techniques in many experiments due to their versatility, sensitivity, and measurability. Topiramate, the objective compound lacks fluorogenic or chromophoric moieties rendering its direct analysis impractical. Without these groups, the molecule lacks the ability to fluoresce or absorb light in its natural state when subjected to a source of ultraviolet radiation. Tagging with a tracking reagent or fluorescent probing can overcome this phenomenon. Under the specific conditions In this study, a new, eco-friendly, practically applicable, and specific fluorometric approach to the assay of none fluorescent drug, topiramate was proposed. The planned analytical approach is dependent on the integration of fluorescence probes through the use of the o-phthalaldehyde reagent to yield a potent fluorescent product that can be measured fluorimetrically. Topiramate's unsubstituted amine moiety can condense with o-phthalaldehyde and thiol moiety in a buffered solution. After being excited at 339 nm. the product was measured at em 440 nm. This technique provides linearity within a concentration scale of 0.1–0.9 µg mL−1. The system quantum yield was evaluated by a comparative method. Also, the probe validation was analyzed in accordance with the standards set by the International Council for Harmonization (ICH). Excipients had no appreciable impact on the proposed probe's performance when testing topiramate in both batch powder and commercially available products. The results show remarkable consistency with the documented reference method with no obvious discrepancies between the two. Finally, the planned system was evaluated from the environmental side through different ecological metrics such as National Environmental Methods Index (NEMI), Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI), and Analytical GREEnness measure (AGREE) and showed a high degree of greenness (ES: 93/100; AGREE 0.75/1 and full green NEMI pictograms).

A novel and unusual utility of the cardiosintol drug as a fluoro-prober in the amendment of a highly fluorescent module for determining the non-fluorescent N-acetylcysteine drug

It is common to use reagents to determine the drugs by exploiting the properties of these reagents in the development of fluorescence of the target drug or sometimes increasing its intensity; this is the usual and predominant in the methods used in various techniques. But using a drug as a reagent to analyze another drug is unique, unusual, and uncommon; that's the idea of this paper. This is possible by creating a chemical modulation in the drug's structure using another drug. Targeted analyte molecules (N-acetylcysteine, as an example) that lack fluorogenic or chromophoric moieties cannot be monitored or evaluated without undergoing structural modification. Thus, the chemical mending of the analyte's molecular structure can achieve the transformational process. This protocoled analytical method generates an amended fluorescence sensation that can be chased fluorimetrically at 441 nm (emission) following excitation at 339 nm. When o-dialdehyde, diformylbenzene, a non-fluorescent moiety, is added to a solution of non-fluorescent analyte in the presence of cardiosintol drug, at a specific pH, the target drug-thiol moiety can be amended into a highly fluorescent compound. This study presented a sensitive and feasible fluorometric test for acetylcysteine. The response is linear throughout the range of 0.05–0.80 µg mL−1. Quantum yield and procedure validation were evaluated according to I.C.H. standards. The formed mutated product was successfully applied to the precise assessment of the studied drug in batch powder and dose form(s), with no impact from excipients. Compared to the referenced publication, the outcomes demonstrate remarkable precision and accuracy.

A tricarbonyl rhenium(I) complex decorated with boron dipyrromethene for endoplasmic reticulum-targeted photodynamic therapy

Organelle-targeted photodynamic therapy (PDT) has recently emerged as a promising strategy for developing effective and precise cancer therapy. Selective generation of highly cytotoxic reactive oxygen species (ROS) in the endoplasmic reticulum (ER) region by PDT can effectively kill cancer cells. In this work, an ER-targeted tricarbonyl Re(I) complex (Re-BDP) was designed and synthesized by combining a tricarbonyl Re(I) unit and a photoactive boron dipyrromethene (BODIPY) chromophore moiety. Complex Re-BDP was characterized by ESI-MS, 1H NMR spectroscopy, FT-IR spectroscopy, and high-performance liquid chromatography (HPLC). The complex displayed strong absorbance (ε = 6.56 × 104/M−1 cm−1 in CH2Cl2) in the visible light region (∼512 nm) and a high singlet oxygen quantum yield (ΦΔ = 0.89 in methanol). Co-localization assays revealed that it accumulated preferentially in the ER. Complex Re-BDP exhibited high phototoxicity upon visible light (525 nm) irradiation toward human cervical cancer HeLa, human lung cancer A549 and human breast cancer MDA-MB-231 cells. Mechanism experiments showed that complex Re-BDP caused reactive oxygen species (ROS) generation and induced ER stress in HeLa cells upon light irradiation, leading to caspase-dependent apoptosis, accompanied by mitochondrial dysfunction. Overall, the results demonstrate that complex Re-BDP is a promising phototherapeutic agent for ER-targeted cancer phototherapy. This work highlights the effectiveness of developing efficient organelle-targeted metal-based phototherapeutic agents by appropriate conjugation of metal complexes and organic chromophores.

Optical, electrochemical and photophysical analyses of heteroleptic luminescent Ln(iii) complexes for lighting applications.

A series of lanthanide complexes have been synthesized with fluorinated 1,3-diketones and heteroaromatic ancillary moieties. Spectroscopic studies reveal the attachment of the respective lanthanide ion to the oxygen site of β-diketone and nitrogen site of auxiliary moieties. The conducting behavior of the complexes is proposed by their optical energy gaps which lie in the range of semiconductors. The emission profiles of the lanthanide complexes demonstrate red and green luminescence owing to the distinctive transitions of Sm3+ and Tb3+ ions, respectively. Energy transfer via antenna effect clearly reveals the effective transfer of energy from the chromophoric moiety to the Ln3+ ion. The prepared conducting and luminescent Ln(iii) complexes might be employed as the emitting component in designing OLEDs.

Effective Fragment Potentials for Microsolvated Excited and Anionic States.

The effective fragment potential (EFP) approach is a sophisticated hybrid approach that allows the inclusion of solvation effects when describing properties and reactivity in the condensed phase, without using empirical parameters. This work examines the performance of the EFP method when describing microsolvation in electronically excited states of neutrals and anions. The examples selected include both localized valence states, as well as diffuse nonvalence states, which represent greater challenges to conventional electronic structure methods. The equation-of-motion coupled cluster with singles and doubles (EOM-XX-CCSD) methodology has been used to provide the quantum chemical description of both the full microsolvated clusters, and the chromophoric moiety in mixed quantum/EFP calculations. We find that, when averaging over multiple configurations of microsolvated clusters, the differences between QM/EFP and full quantum results are minimal, although individual configurations often have larger errors. As expected, diffuse states have somewhat larger errors, although not significantly so. The close proximity of states leading to mixing can make QM/EFP less accurate because a change of ordering of states can occur. Other properties, such as photoelectron images and lifetimes of metastable states, are very well described for the monohydrated clusters investigated.

Oxidative depolymerization of kraft lignin assisted by potassium tert-butoxide and its effect on color and UV absorption

A chemically mild methodology was demonstrated to obtain decomposed lignin products via oxidative depolymerization. We effectively produced light-colored lignin materials with low molecular weight and narrow molecular weight distribution by simple agitation at ambient temperature and pressure in the presence of potassium tert-butoxide and gaseous oxygen. This oxidative depolymerization dissociated various lignin bonding structures and oxidized aliphatic hydroxyl groups of lignin, expanding conjugated system within the depolymerized lignin molecules. This chemical transformation resulted in the generation of effective chromophoric moieties to enhance the UV absorption property of the resulting depolymerized products, which showed a significant improvement in the sun protection capability.

Contact-Mediated Retinal-Opsin Coupling Enables Proton Pumping in Gloeobacter Rhodopsin.

When a chromophore embedded in a photoreceptive protein undergoes a reaction upon photoexcitation, the photoreaction triggers structural changes in the protein moiety that are necessary for the function of the protein. It is thus essential to elucidate the coupling between the chromophore and protein moiety to understand the functional mechanism for photoreceptive proteins, but the mechanism by which this coupling occurs remains poorly understood. Here, we show that nonbonded atomic contacts play an essential role in driving functionally important structural changes following photoisomerization of the chromophore in Gloeobacter rhodopsin (GR). Time-resolved ultraviolet resonance Raman spectroscopy revealed that the substitution of Trp222, which contacts with methyl groups of the retinal chromophore, with a Phe residue reduced the extent of structural change. The proton-pumping activity of the GR mutant was as small as 9% of that of the wild type. Time-resolved visible absorption and resonance Raman spectra showed that the photocycle of the mutant proceeded to the L intermediate following the all-trans to 13-cis photoisomerization step but did not result in the deprotonation of the chromophore. The present results demonstrate that the atomic contacts between the chromophore and the Trp222 side chain induce the structural changes necessary for proton transfer. The requirement for dense atomic packing in a protein structure for the efficient propagation of structural changes through a coupling mechanism is discussed.

Synthesis, Application, and Antibacterial Activity of New Direct Dyes based on Chromene Derivatives.

This study aimed at synthesizing, analyzing, and utilizing two new direct dyes based on chromene derivatives as the chromophoric moiety in dyeing wool, silk, and cotton, with good color strength, light fastness, and other desirable features. New direct dyes with antimicrobial activities for Gram-positive, Gram-negative bacteria, and fungus are being developed. These dyes are used on cotton, silk, and wool materials, which have excellent light fastness, washing, rubbing, and perspiration fastness. All dyeing fabrics were tested for antibacterial activity. As a part of the experiment, parent structure 1 was previously synthesized. Then, diazotization and coupling reactions were used to prepare these dyes. P-Aminobenzenesulfonic acid (C1) and 4-Aminoazobenzene-3,4'-disulfonic acid (C2) were diazotized in hydrochloric acid with sodium nitrite and then coupled with compound 1 in a molar ratio of 1:1 at 25 °C until the pH was fixed at 5. Finally, the monoazo and diazo direct dyes (D1 and D2) were prepared. Wool, silk, and cotton materials benefit from the increased antibacterial activities and dyeing qualities (exhaustion and fixing) of synthetic dyes. Furthermore, they offer excellent fastness qualities (light, rubbing, and perspiration).

Steric and Electronic Origins of Fluorescence in GFP and GFP-like Proteins.

Fluorescent proteins have become routine tools for biological imaging. However, their nanosecond lifetimes on the excited state present computational hurdles to a full understanding of these photoactive proteins. In this work, we simulate approximately 0.5 nanoseconds of ab initio molecular dynamics to elucidate steric and electronic features responsible for fluorescent protein behavior. Using green fluorescent protein (GFP) and Dronpa2─widely used fluorescent proteins with contrasting functionality─as case studies, we leverage previous findings in the gas phase and solution to explore the deactivation mechanisms available to these proteins. Starting with ground-state analyses, we identify steric (the distribution of empty pockets near the chromophore) and electronic (electric fields exerted on chromophore moieties) factors that offer potential avenues for rational design. Picosecond timescale simulations on the excited state reveal that the chromophore can access twisted structures in Dronpa2, while the chromophore is largely confined to planarity in GFP. We couple ab initio multiple spawning (AIMS) and enhanced sampling simulations to discover and characterize conical intersection seams that facilitate internal conversion, which is a rare event in both systems. Our AIMS simulations correctly capture the relative fluorescence profiles of GFP and Dronpa2 within the first few picoseconds, and we attribute the diminished fluorescence intensity of Dronpa2, relative to GFP, to flexible chromophore intermediates on the excited state. Furthermore, we predict that twisted chromophore intermediates produce red-shifted intensities in the Dronpa2 fluorescence spectrum. If confirmed experimentally, this spectroscopic signature would provide valuable insights when screening and developing novel fluorescent proteins.

Methacrylic copolymers with quinoxaline chromophores in the side chain exhibiting quadratic nonlinear optical response

AbstractThe first example of polymer materials containing in the side chain original D‐π‐A chromophore with quinoxaline core in the π‐electron bridge is presented and their quadratic nonlinear optical (NLO) activity is studied. Two synthetic procedures: esterification and radical copolymerization, are used to obtain methacrylic copolymers P1Ch and P2Ch, respectively, which contain chromophores with quinoxaline moiety in various concentrations (4, 6, 7, and 9 mol%). Atomistic modeling has shown that introduction of chromophores in polymer side chains results in less pronounced chromophore aggregation in the material compared with the case of relative composites. NLO coefficients of the thin films obtained on the basis of copolymers P1Ch and P2Ch and composite material PMMA/AEEA‐VQV‐TCF with relative chromophore‐guest are up to 40, 21, and 43 pm/V, respectively, at chromophore content 25 wt%. Covalent attachment of chromophore moiety to the polymer side chain is shown to improve the temporal and thermal stability of the material NLO coefficient compared with that of the composite material.