Pyrene Groups Research Articles

Mesomorphic Behavior of Symmetric Azomethine Dimers Containing Different Chromophore Groups.

A series of new azomethine dimers was synthesized by the condensation reaction of flexible bis-benzaldehydes with four aromatic amines containing phenyl, naphthyl, anthracene and pyrene groups. Their right structure was confirmed by FTIR and 1H-NMR spectroscopy and their thermal properties were investigated by thermogravimetric analysis, differential scanning calorimetry and polarized light optical microscopy. A view on their photophysical behavior was gained by UV-vis and photoluminescence spectroscopy. The dimers containing pyrene and anthracene presented liquid crystalline behavior, while the other dimers were crystalline compounds. Two dimers containing pyrene moieties formed mesomorphic glasses and had intense luminescence, promising properties for applications in building optoelectronic devices.

Catalytic Enantioselective Dehydrogenative Si-O Coupling to Access Chiroptical Silicon-Stereogenic Siloxanes and Alkoxysilanes.

A rhodium-catalyzed enantioselective construction of triorgano-substituted silicon-stereogenic siloxanes and alkoxysilanes is developed. This process undergoes a direct intermolecular dehydrogenative Si-O coupling between dihydrosilanes with silanols or alocohols, giving access to a variety of highly functionalized chiral siloxanes and alkoxysilanes in decent yields with excellent stereocontrol, that significantly expand the chemical space of the silicon-centered chiral molecules. Further utility of this process was illustrated by the construction of CPL-active (circularly polarized luminescence) silicon-stereogenic alkoxysilane small organic molecules. Optically pure bis-alkoxysilane containing two silicon-stereogenic centers and three pyrene groups displayed a remarkable glum value with a high fluorescence quantum efficiency (glum = 0.011, ΦF = 0.55), which could have great potential application prospects in chiral organic optoelectronic materials.

Highly Crosslinked and Clickable Poly(divinylbenzene) Microspheres by Type II Photoinitiated Precipitation Polymerization

AbstractA new method for the synthesis of highly crosslinked and in situ alkyne functionalized microspheres, by combining type II photoinitiation with precipitation polymerization, is reported. Using a benzophenone‐tertiary amine initiation system, the method allows the preparation of functional microspheres at room temperature by UV irradiation in the absence of stabilizers or surfactants of any kind. To demonstrate the presence and accessibility of the alkyne moiety on the polymer particles, fluorescent pyrene groups are attached to the microspheres by copper(I)‐catalyzed alkyne‐azide cycloaddition click reaction, using 1‐azidomethyl pyrene as a model compound. FT‐IR, fluorescence spectroscopy, fluorescence microscopy, and scanning electron microscopy are used for characterization of the particles and to monitor the click reaction.

Detection of an IL-6 Biomarker Using a GFET Platform Developed with a Facile Organic Solvent-Free Aptamer Immobilization Approach.

Aptamer-immobilized graphene field-effect transistors (GFETs) have become a well-known detection platform in the field of biosensing with various biomarkers such as proteins, bacteria, virus, as well as chemicals. A conventional aptamer immobilization technique on graphene involves a two-step crosslinking process. In the first step, a pyrene derivative is anchored onto the surface of graphene and, in the second step, an amine-terminated aptamer is crosslinked to the pyrene backbone with EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide) chemistry. However, this process often requires the use of organic solvents such as dimethyl formamide (DMF) or dimethyl sulfoxide (DMSO) which are typically polar aprotic solvents and hence dissolves both polar and nonpolar compounds. The use of such solvents can be especially problematic in the fabrication of lab-on-a-chip or point-of-care diagnostic platforms as they can attack vulnerable materials such as polymers, passivation layers and microfluidic tubing leading to device damage and fluid leakage. To remedy such challenges, in this work, we demonstrate the use of pyrene-tagged DNA aptamers (PTDA) for performing a one-step aptamer immobilization technique to implement a GFET-based biosensor for the detection of Interleukin-6 (IL-6) protein biomarker. In this approach, the aptamer terminal is pre-tagged with a pyrene group which becomes soluble in aqueous solution. This obviates the need for using organic solvents, thereby enhancing the device integrity. In addition, an external electric field is applied during the functionalization step to increase the efficiency of aptamer immobilization and hence improved coverage and density. The results from this work could potentially open up new avenues for the use of GFET-based BioMEMS platforms by broadening the choice of materials used for device fabrication and integration.

Multifunctional Flexible Polyimides for Electroactive Devices with Electrochromic, Electrofluorochromic, and Photodetection Properties

In this study, we report three electroactive carbazolyl polyimides (PIs) containing spiropyran, pyrene, and fluorescein fluorescent groups. The PIs exhibit red, blue, and green fluorescence emissio...

Electrocatalytic hydrogen evolution using hybrid electrodes based on single-walled carbon nanohorns and cobalt(ii) polypyridine complexes

An unprecedented combination of porous SWCNHs with tetradentate polypyridine cobalt(ii) complexes bearing pyrene groups has been realized to produce a hybrid cathode active for the hydrogen evolution reaction (HER) in water at neutral pH.

The modification of a pyrene group makes a Ru(ii) complex versatile.

In this work, the simple modification of a pyrene group on the labile ligand gives the resultant complex 1 versatility, for example, "turn-on" fluorescence after photo-dissociation, dual PDT and PACT activity, and a large two-photon absorption cross section.

Luminescent [ZnIILnIII] complexes anchored on graphene: Synthesis and crystal structures of [ZnIIEuIII] and [ZnIITbIII] complexes decorated with pyrene groups

Two [ZnLn] heterobinuclear complexes decorated with pyrene groups, [ZnEu(valpn)(hfac)2(pb)], have been obtained, in order to be deposited on graphene (LnIIIEuIII 2a; TbIII 2b); H2valpn is the Schiff base compartmental ligand resulted from the condensation reaction between o‐vanillin and propylenediamine (Hpb = 1‐pyrenebutiric acid; Hhfac = hexafluoroacetylacetone). The two complexes have been obtained by replacing the acetato ligand in [ZnEu(valpn)(hfac)2(CH3COO)] (EuIII: 1a; TbIII: 1b) by pb− anions. The crystal structures of 1a, 2a, and 2b have been solved and described. Compounds 2a and 2b were grafted on monolayer graphene/quartz. The new hybrid materials, 2a/graphene and 2b/graphene, as well as the starting complexes are luminescent. The two hybrid materials have been characterized by Raman spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) measurements, which confirm the presence of the complexes on graphene.

Water-soluble polyaromatic-based imidazolium for detecting picric acid: Pyrene vs. anthracene

Highly water-soluble fluorescent polyaromatic-based imidazolium compounds capable of detecting a wide-range of nitroaromatics, e.g., nitrophenols and picric acid in aqueous solution with fully quenched fluorescence are reported. The two probes contained an anthracene and pyrene group with the increased size and angularity of the pyrene ring in pyrene-based imidazolium (PIM) raising the hydrophobicity or π-π stacking and sensitivity of the probe towards all mono-, di-, and trinitrophenols even under harsh conditions (pH 4-8). The high affinity for nitrophenols was confirmed by single crystal X-ray crystallography. Time-dependent density functional theory (TD-DFT) reveals cation-anion interactions between the imidazolium and picrate ions causing fluorescent quenching through PET and charge transfer involving a dark S1 excited state.

A pyrene-containing Schiff base fluorescent ratiometric probe for the detection of Cu2+ in aqueous solutions and in cells

A highly selective and sensitive fluorescent ratiometric probe (1) based on pyrene-containing Schiff base for the dection of Cu2+ was synthesized. In acetonitrile–HEPES buffer solution (20.0 mM HEPES, 8:2, v/v, pH 7.4), only Cu2+, out of tested common cations, could induce the aggregation of probe 1. Fluorescence analysis showed that the excimer emission band of pyrene groups of probe 1 appeared and gradually increased with the addition of Cu2+. The fluorescent intensity ratio of excimer and monomer (I470/I409) of probe 1 increased 27.8-fold upon the addition of one equiv. of Cu2+ with a detection limit of 20.2 nM (1.28 ppb). The addition of Cu2+ also induced obvious color change and the characteristic peaks of pyrene excimer in UV–vis spectrometra of the relutant solution. Results from the Job plot, metal-binding fluorescent titration, mass spectra experiments and density functional theory calculations indicated a binding ratio of 2:1 (probe 1: Cu2+). In addition, probe 1 showed good potential as a fluorescent visualizing probe for the detection of Cu2+ in living GS cells of epinepheluscoioides.

Tinospora cordifolia and arabinogalactan exert chemopreventive action during benzo(a)pyrene-induced pulmonary carcinogenesis: studies on ultrastructural, molecular, and biochemical alterations.

The aim of the present study was to unveil the chemopreventive potentials of aqueous Tinospora cordifolia stem extract and its active component viz. Arabinogalactan against Benzo(a)pyrene-induced pulmonary carcinogenesis. Animals were divided into six groups: (I) Control, (II) aqueous Tinospora cordifolia (200 mg/kg b.wt, p.o.), (III) arabinogalactan (7.5 mg/kg b.wt, p.o.), (IV) benzo(a)pyrene (50 mg/kg b.wt, i.p.) at second and fourth week of study, (V) benzo(a)pyrene + aqueous Tinospora cordifolia, and (VI) benzo(a)pyrene + arabinogalactan. The benzo(a)pyrene treatment resulted in severe alterations in the cellular arrangement and morphology of the alveolar tissue in benzo(a)pyrene group. However, benzo(a)pyrene + aqueous Tinospora cordifolia and benzo(a)pyrene + arabinogalactan groups revealed classical features of apoptosis including chromatin condensation and formation of apoptotic bodies. Furthermore, Fourier transform Infrared spectroscopy analysis showed disturbed phospholipid saturation and protein secondary structures in benzo(a)pyrene treated animals. Depletion in relative glycogen and enhancement in total nucleic acid content was observed in benzo(a)pyrene treated animals, and the same was found to be restored upon arabinogalactan and aqueous Tinospora cordifolia supplementation. Benzo(a)pyrene insult also upregulated the phase I carcinogen metabolizing enzymes and differentially modulated the phase II metabolizing enzymes during pulmonary carcinogenesis. Also, depleted (reduced glutathione) and increased lipid peroxidation levels were observed in benzo(a)pyrene treated animals, which was found to be normalized upon aqueous Tinospora cordifolia and arabinogalactan administration. Clastogenic damage inflicted by benzo(a)pyrene was also reversed in benzo(a)pyrene + aqueous Tinospora cordifolia and benzo(a)pyrene + arabinogalactan group. Thus, the present study infers that aqueous Tinospora cordifolia and arabinogalactan showed promising anticancer activity against lung tumorigenesis in terms of ultrastructural, biochemical, and biomolecular aspects.

Synthesis, processability and photoluminescence of pyrene-containing polyimides

Summary Four different contents of pyrene group were introduced in polyimide (PI) backbone via one step polycondensation procedure. The chemical structure, thermal property, process ability, and photophysical performance of polymers were characterized and analyzed. The obtained PIs exhibited high glass-transition temperatures from 270 to 285 °C, and weight remainder rates of PIs were all above 50% at 800 °C in N2. Fluorescence detection of metal ions was taken by adding Cu2+, Pb2+, Cr3+, Cd2+, Fe3+, Co2+, and Ni2+ to polymer solutions. It was interesting to found that the polymer exhibited significant luminescence emission “turn-on” response to Cu2+ and fluorescence emission quenching to Fe3+. Furthermore, the uniform morphologies of pyrene-containing PI fibers were prepared via electrospinning technique for investigating their optical properties in solid state. The fluorescent images and optical photographs indicated that the luminescence stability of polymers in fiber solid state was decided by both the chromophore in macromolecular chain and effective draft of polymer chains during spinning process. This study provided a facility strategy for controlling the morphology structure of materials and keeping the PL emission intensity in flexible devices.

Pyrene Excimer-Based Fluorescent Labeling of Cysteines Brought into Close Proximity by Protein Dynamics: ASEM-Induced Thiol-Ene Click Reaction for High Spatial Resolution CLEM.

Fluorescence microscopy (FM) has revealed vital molecular mechanisms of life. Mainly, molecules labeled by fluorescent probes are imaged. However, the diversity of labeling probes and their functions remain limited. We synthesized a pyrene-based fluorescent probe targeting SH groups, which are important for protein folding and oxidative stress sensing in cells. The labeling achieved employs thiol-ene click reactions between the probes and SH groups and is triggered by irradiation by UV light or an electron beam. When two tagged pyrene groups were close enough to be excited as a dimer (excimer), they showed red-shifted fluorescence; theoretically, the proximity of two SH residues within ~30 Å can thus be monitored. Moreover, correlative light/electron microscopy (CLEM) was achieved using our atmospheric scanning electron microscope (ASEM); radicals formed in liquid by the electron beam caused the thiol-ene click reactions, and excimer fluorescence of the labeled proteins in cells and tissues was visualized by FM. Since the fluorescent labeling is induced by a narrow electron beam, high spatial resolution labeling is expected. The method can be widely applied to biological fields, for example, to study protein dynamics with or without cysteine mutagenesis, and to beam-induced micro-fabrication and the precise post-modification of materials.

Synthesis, characterization and chemical sensor applications of pyrene side‐functional polylactide copolymers

AbstractA novel polylactide (PLA) polymer containing pyrene side groups (P2) was synthesized and employed as a nitroaromatic compound (NAC) and heavy metal ion (HMI) sensing chemical probe. P2 was prepared in a four‐step reaction sequence, including azidification, esterification, ring opening polymerization and click reactions. First, an azido functional cyclic carbonate monomer (ADTC) was synthesized and then a copolymer of l‐lactide and ADTC monomers was synthesized to obtain PLA with azido functional groups (P(LA‐co‐ADTC), P1). Finally, P1 was modified with pyrene groups using ‘click chemistry’ which is a highly effective modification method (P2). The chemical structures and molecular characteristics of the obtained polymers were clearly verified via Fourier transform infrared spectroscopy, gel permeation chromatography and 1H NMR analysis techniques and the fluorescence properties were examined via UV–visible and fluorescence spectrometry. The prepared P2 polymers were employed as a fluorescent probe towards certain HMI (Zn2+, Hg2+, Mn2+, Pb2+, Cd2+, Co2+) compounds and NACs (1,2‐dinitrobenzene, 2,4‐dinitrotoluene, 2,4,6‐trinitrophenol (picric acid, PA), 4‐nitrophenol (4‐NP), 2,4‐dinitrophenol (2,4‐DNP), 2,4,6‐trinitrotoluene, 4‐nitrotoluene). The fluorescence intensity of the P2 polymers was gradually reduced upon the addition of NACs and HMIs. For all compounds, the highest quenching efficiencies were attained in the presence of PA (94.03%), 4‐NP (91.11%) and 2,4‐DNP (89.08%). Because of its simplicity and sensitivity, the proposed P2 polymers can be especially considered as potential chemical probes to detect NACs. © 2020 Society of Industrial Chemistry

Dinuclear copper(II) complexes with derivative triazine ligands as biomimetic models for catechol oxidases and nucleases

The research reported herein focuses on the synthesis of two new Cu(II) complexes {[Cu2(2-X-4,6-bis(di-2-picolylamino)-1,3,5-triazine], with X = butane-1,4-diamine (2) or N-methylpyrenylbutane-1,4-diamine (3)}, the latter with a pyrene group as a possible DNA intercalating agent. The structure of complex (3) was determined by X-ray crystallography and shows the dinuclear {CuII(μ-OCH3)2CuII} unit in which the CuII···CuII distance of 3.040 Å is similar to that of 2.97 Å previously found for 1, which contains a {CuII(μ-OH)2CuII} structural unit. Complexes (2) and (3) were also characterized in spectroscopic and electrochemical studies, and catecholase-like activity were performed for both complexes. The kinetic parameters obtained for the oxidation of the model substrate 3,5-di-tert-butylcatechol revealed that the insertion of the spacer butane-1,4-diamine and the pyrene group strongly contributes to increasing the catalytic efficiency of these systems. In fact, Kass becomes significantly higher, indicating that these groups influence the interaction between the complex and the substrate. These complexes also show DNA cleavage under mild conditions with moderate reaction times. The rate of cleavage (kcat) indicated that the presence of butane-1,4-diamine and pyrene increased the activity of both complexes. The reaction mechanism seems to have oxidative and hydrolytic features and the effect of DNA groove binding compounds and circular dichroism indicate that all complexes interact with plasmid DNA through the minor groove. High-resolution DNA cleavage assays provide information on the interaction mechanism and for complex (2) a specificity for the unpaired hairpin region containing thymine bases was observed, in contrast to (3).

Graphdiyne:Structure of Fluorescent Quantum Dots.

Graphdiyne (GDY) as an emerging two-dimensional carbon allotrope exhibits excellent performance in energy chemistry, catalytic chemistry, optoelectronics, electronics, etc. because of the unique structure combining an sp- and sp2 -hybrid carbon network. However, the poor solubility of pristine GDY is a major obstacle to its applications in many fields. Proposed here is a facile strategy to control the preparation of GDY quantum dots (GDY-Py QDs), in which pyrene groups are covalently linked to GDY by using a Sonogashira cross-coupling reaction. The as-prepared GDY-Py QDs, with an average diameter of about 3±0.1 nm, show superior dispersibility in many organic solvents and water. The GDY-Py QDs display not only bright fluorescent with a high relative quantum yield (QY) of 42.82 %, but they are also well-behaved as contrast agents in cell imaging. The GDY-Py QDs are bestowed with high stability and non-cytotoxicity, and exhibit long fluorescent times, and have potential for optical imaging and biomedical applications.

Graphdiyne:Structure of Fluorescent Quantum Dots

AbstractGraphdiyne (GDY) as an emerging two‐dimensional carbon allotrope exhibits excellent performance in energy chemistry, catalytic chemistry, optoelectronics, electronics, etc. because of the unique structure combining an sp‐ and sp2‐hybrid carbon network. However, the poor solubility of pristine GDY is a major obstacle to its applications in many fields. Proposed here is a facile strategy to control the preparation of GDY quantum dots (GDY‐Py QDs), in which pyrene groups are covalently linked to GDY by using a Sonogashira cross‐coupling reaction. The as‐prepared GDY‐Py QDs, with an average diameter of about 3±0.1 nm, show superior dispersibility in many organic solvents and water. The GDY‐Py QDs display not only bright fluorescent with a high relative quantum yield (QY) of 42.82 %, but they are also well‐behaved as contrast agents in cell imaging. The GDY‐Py QDs are bestowed with high stability and non‐cytotoxicity, and exhibit long fluorescent times, and have potential for optical imaging and biomedical applications.

Melatonin supplementation protects against the benzo(e)pyrene cytotoxicity and optic cup formation disruption in chicken embryos

Benzo(e)pyrene is a cytotoxic chemical to the
 eyes, while neurohormone melatonin may exhibit protective effects on this
 cytotoxicity. In the current study, we have investigated the cytotoxic effects
 of benzo(e)pyrene on the chicken embryonic optic cups formation and whether
 melatonin supplementation protects chicken embryos against this xenobiotic
 toxicity. Fertilized chicken eggs were incubated for 48 h and then, they were
 divided into different groups. These groups included basal (without any
 treatment), control (distilled water), benzo(e)pyrene, melatonin and
 benzo(e)pyrene + melatonin groups, respectively. The 10 µl of distilled water
 or same volume of solution containing treatment compounds were injected into
 the air sac of the chicken egg. After an additional 18 h of incubation, the
 chicken embryos were excised and analyzed. The cytotoxicity was measured by a
 colorimetric whole chick embryo trypan blue assay. In embryos from basal,
 control and melatonin (0.01, 1 and 100 µM) groups, the frequency of the embryos
 with normal optic cups was 100% and had no increase in the embryonic cell death
 observed in post excision. In contrast, the frequency of normal optic cups in the
 benzo(e)pyrene (0.02 to 1200 µM) groups was significantly reduced (log IC50=
 -4.24 ± 0.02, R2= 0.98) with concentration-responsive manner. In
 addition, an increase in the embryonic cell death was also observed (log IC50 =
 -7.23 ± 0.28; R2 = 0.63). Melatonin treatment dose-responsively inhibited
 the benzo(e)pyrene-induced optic cups abnormality by 22.35 ± 4.06, 76.38 ± 3.30
 and 100 % at the concentrations of 0.01, 1 and 100 µM, respectively. This same
 phenomenon was also observed in benzo(e)pyrene-induced embryonic cell death,
 i.e., melatonin suppressed the embryonic cell death by 16.67 ± 4.17, 54.17 ±
 4.17 and 100 % with the abovementioned concentrations, respectively. Thus, melatonin
 supplementation injected into the chicken eggs protected against the
 benzo(e)pyrene embryotoxicity. Different pathways can be involved in melatonin’s
 protective effects.

Modular Synthesis and Structure–Property Correlation of Pyrene – Rylene Dyes for Cellular Imaging

Polycyclic aromatic hydrocarbon with extended conjugation and broad absorption properties are interesting due to their easy accessibility, response to external stimuli and high stability. Herein, we report synthesis and full characterization of four compounds having multiple photoactive units in conjugation with a central pyrene group. The compound 2 with extended conjugation showed high fluorescence intensity in the solid state. Since the target molecules are non‐toxic and highly fluorescent, water dispersible nanoparticles were prepared from these molecules and explored for cellular imaging.

(Invited) Electroactive Redox Polymers, Redox Glyconanoparticles and Supramolecular Assemblies Based on Nanotubes for Bioelectrochemical Applications

For four decades, the development of biointerfaces has been the subject of increasing research efforts in the field of analytical chemistry and energy conversion. In particular, the functionalization of electrodes by biomaterials based on electrogenerated polymers and / or carbon nanotubes, is widely used for the design of biosensors and biofuel cells. Nanotube deposits were successfully functionalized by electropolymerization or π−π stacking interactions with pyrene derivatives exhibiting both affinity or covalent binding interactions towards redox molecules or proteins. Some new approaches for developing nanostructured biomaterials based on functionalized tungsten disulfide nanotubes and self-supporting film of carbon nanotubes (buckypapers) will be illustrated with enzymes as biosensing element [1]. In particular, WS2 nanotubes functionalized with carboxylic acid functions were used for the tyrosinase immobilization in order to form an amperometric biosensor towards catechol and dopamine. Moreover, heteropolyoxometalates (C4H10N)6[P2Mo18O62] and (C6H8NO)4[H2P2W18O62] were immobilized within carbon nanotube matrix and used as mediators for the electron transfer with FAD dependent glucose dehydrogenase [2]. The glucose detection was performed with a sensitivity of 198 mAmolL-1cm-2, and a good reproducibility. A new generation of flexible buckypaper electrodes was produced by using linear polynorbornene polymers containing multiple pyrene groups as crosslinker [3]. In addition, the use of bifunctionalized polymers (pyrene and NHS groups) leads to robust buckypapers with the covalent binding of redox groups or enzymes [4].We have been also interested in the development and characterization of glyconanoparticles (vesicles, micelle aggregates) obtained from the self-assembly of block copolymers composed of polystyrene as a hydrophobic tail and cyclodextrin as a hydrophilic part. These glyconanoparticles, which are stable in suspension in aqueous media, have an outer layer composed of cyclodextrin which allows a post-functionalization of the nanoparticle by hydrophobic molecules through host-guest interactions. These nanoparticles are thus a versatile platform for fixing a wide range of redox mediators. Two types of redox nanoparticles in solution for the electrical connection of enzymes have been developed: nanoparticle modified by 9,10-phenanthrenequinone and nanoparticle modified by ABTS modified by two pyrene groups. This innovative approach will be applied to the electrical wiring of enzymes in solution for the elaboration of solubilized enzymatic fuel cell [5,6]. Acknowledgements The author wishes to acknowledge the support from the Sino-French international research network GDRI 0876 “New nanostructured materials and biomaterials for renewable electrical energy sources” for providing facilities. This work is partly supported by the French National Research Agency (ANR-18-CE09-0022-01).[1]