Pyrene Groups Research Articles

Ultrafast Charge Separation Driven by Solvation-Coupled Intramolecular Torsion.

Photoinduced intramolecular charge separation in a pyrene- and triarylamine-based donor-acceptor dyad was studied by polarization-dependent femtosecond time-resolved transient absorption (TA) spectroscopy in polar solvents. Photoexcitation forms an excited state with charge transfer (CT) character due to the intrinsic electronic coupling between the triarylamine and pyrene groups, resulting in ultrafast charge separation (CS) in polar solvents. TA measurements reveal a correlation between the rate of CS and solvation dynamics, which implies that solvation is involved in the CS reaction. In addition, polarization-dependent TA spectroscopy was devoted to tracking the ultrafast anisotropy evolution of the cationic absorption band, which is attributed to intramolecular torsional motion and is proposed to be coupled to diffusive orientational solvent modes. The results therefore reveal that the evolution of the CT state in the condensed phase is driven by solvation-coupled excited-state structural relaxation. In other words, intramolecular torsional motion is directly confirmed to be involved in the reaction coordinate of the CS reaction in a strongly coupled donor-acceptor dyad.

Fluorescence switching of triarylamine-based polyamides with pendant pyrene units and its application in electrochromic smart displays

The pyrene group was directly connected to the triarylamine (TAA) unit through a benzene bridge via the Suzuki reaction to successfully prepare the diamine monomer. A series of new polyamides (PAs) based on TAA units were prepared by polycondensation. The PAs exhibited good solution processability and high thermal stability with the char yield in excess of 53% at 800°C in air atmosphere. In solvents with different polarities, these PAs showed solvatochromic effect and large stokes shift. Strongly photoluminescent PAs have a sensitive stimulus response to explosive and hazardous gas, and its fluorescence is easily turned off by the addition of trinitrophenol (TNP) and hydrogen chloride (HCl). And achieve fluorescence switching between exposure to HCl and ammonia (NH3) gas. The PAs exhibited a reversible color response in the electrochemical oxidation process, with no significant degradation in current and transmittance after 200 cycles. The sandwich structure multicolor electrochromic device can achieve electrochromic performance applied by different voltages.

Understanding the Adsorption and Diffusion Behaviors of PBUT in Biocompatible MOFs.

With the increasing incidence of chronic kidney disease, the effective control of protein-bound uremic toxins (PBUTs), which are difficult to remove through dialysis, has become a priority. In this study, the adsorption and diffusion behaviors of several metal-organic frameworks (MOFs) for PBUTs (indoxyl sulfate and p-cresyl sulfate) were studied by molecular dynamics (MD) simulations and umbrella sampling. For the NU series of MOFs, good correlations between the Gibbs free energy (ΔG) and the experimental clearance rates of PBUTs are found. For the adsorption behaviors, in terms of ΔG, DAJWET exhibits the best adsorption effect for indoxyl sulfate (IS), whereas NU-1000 shows the best effect for p-cresyl sulfate (pCS). Similar trends observed in the radial distribution function and mean square displacement results suggest that the π-π stacking interactions play a crucial role in the adsorption and diffusion of PBUTs by MOFs. Furthermore, it can be concluded that MOFs with highly conjugated groups (porphyrin rings and pyrene groups) tend to generate more PBUT attraction, and provide design principles for potential MOF candidates in the removal of PBUTs.

(Invited) Developing a Graphene Field-Effect Biosensor for Genetic Biomarkers: Simulations Unveil How the Device Sensitivity Is Related to DNA-Graphene Interactions at the Nanoscale

Graphene field-effect transistor biosensors (GFETs) offer a promising platform to detect cancer DNA biomarkers at low concentration [1]. At their core, they have an electronic circuit containing a graphene sheet – a two-dimensional nanomaterial made of a single layer of carbon atoms – whose electronic properties are very sensitive to nearby electric charges. Leveraging that feature, the electrical current generated by a GFET can thus be made very sensitive to the concentration of a specific DNA sequence in a biological sample. To achieve this, the complementary DNA sequence is linked to the graphene to bind specifically the target DNA. In most GFETs, the link is done using 1-pyrenebutanoic acid succinimidyl ester (PBASE) because its pyrene group stacks on the graphene through pi-pi interactions, without disrupting the electronic properties of the graphene. However, recent experiments in the Bouilly group have shown variations in GFET sensitivity depending on the incubation time of graphene with PBASE.Here, we use a computational approach developed in our previous work [2] to investigate at the nanoscale the role of PBASE linker molecules on the sensitivity of the GFET. First, we use molecular dynamics simulations to characterize the conformational ensemble of a 10-nt single-stranded DNA sequence linked to a graphene sheet using PBASE. Second, we estimate the electrical response of the GFET from the electrostatic potential generated by these DNA conformations on the graphene, as determined using electrostatic Poisson-Boltzmann simulations. Our results show that the conformational ensemble of DNA is strongly affected by the presence of other PBASE adsorbed on the graphene, thus changing the electrostatic potential generated on the graphene. The predicted change of the electrostatic potential should impact measurably the detection signal of the GFET.We are now using these simulations to explain the experimental characterizations of a GFET designed to detect a genetic biomarker important in breast cancer profiling. Our simulations have the potential to support the development of GFETs with better sensitivity for DNA detection.[1] Béraud, A., Sauvage, M., Bazán, C. M., Tie, M., Bencherif, A., and Bouilly, D. (2021) Graphene field-effect transistors as bioanalytical sensors: design, operation and performance. Analyst. 146:403-428.[2] Côté, S., Mousseau, N., and Bouilly, D. (2022) The molecular origin of the electrostatic gating of single-molecule field-effect biosensors investigated by molecular dynamics simulations. Phys. Chem. Chem. Phys. 24:4174-4186.

The influence of metal-free thiophene spacer chain on optoelectronic analysis by TD-DFT method for efficient dye-sensitized solar cells with enhanced non-linear optical activity

The pyrene group in conjugation with the thiophene moiety was used to design new organic molecules for the dye-sensitized solar cells (DSSCs) along with non-linear optical (NLO) properties. Five new thiophene chain conjugation molecules (PTRA-SPn, n = 1–5) were formed based on the (E)-2-(5-oxo-4-((5-(pyren-1-yl)thiophen-2-yl)methylene)-2-thioxothiazolidin-3-yl)acetic acid (PTRA). To comprehend the function of conjugation in varying the optoelectronic characteristics of these compounds, the π-spacer chain has been screened. The techniques of density functional theory (DFT) and time-dependent DFT (TD-DFT) have been used to study the electronic structures, Ultraviolet–Visible (UV–Vis) absorptions, and NLO activities of donor-spacer-acceptor (D-π-A) structures. According to the computed results, PTRA-SP5 exhibits a smaller energy gap (Eg) of 2.11 eV. The maximum UV–Vis spectrum has been found in PTRA-SP5 with a wavelength (λmax) of 532 nm. The reorganizational energy (RE) and dye regeneration (ΔGreg) of PTRA-SP5 are the smallest (λ- = 0.2340 eV, λ+ = 0.2122 eV, ΔGreg = 0.21 eV) compared to other sensitizers. The lowest exciton binding energies (Eb) of PTRA-SP2 (0.06 eV) and PTRA-SP3 (0.06 eV) are the lowest ones. The open circuit photovoltage (eVoc) for PTRA-SP5 (1.10 eV) is the highest. The NLO activity of the dipole moment (μnormal) and first-order hyperpolarizability (β) values of PTRA-SP5 achieve higher values (9.00 Debye and 34.82 × 10−30 esu, respectively). In summary, this work refined the impact of chain π-linkers on the photophysical characteristics of D-π-A spacer derivatives and offered some helpful suggestions to create new organic materials for optoelectronic uses.

Experimental and kinetic evaluation on cobalt Salen conjugated organic polymers for CO2 cycloaddition reactions and iodine vapor adsorption

The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The Ea was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics.

Quasi-Chromophores Segregated by Single-Chain Nanoparticles of Fluorinated Zwitterionic Random Copolymers Showing Remarkably Enhanced Fluorescence Emission Capable of Fluorescent Cell Imaging.

Organic and polymer fluorescent nanomaterials are a frontier research focus. Here in this work, a series of fluorinated zwitterionic random copolymers end-attached with a quasi-chromophoric group of pyrene or tetraphenylethylene (TPE) are well synthesized via atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP). Those random copolymers with total degree of polymerization 100 or 200 are able to produce fluorescent single-chain nanoparticles (SCNPs) through intra-chain self-folding assembly with quite uniform diameters in the range of 10-20nm as characterized by dynamic light scattering and transmission electron microscopy. By virtue of the segregation or confinement effect, both SCNPs functionalized with pyrene or TPE group are capable of emitting fluorescence, with pyrene tethered SCNPs exhibiting stronger fluorescence emission reaching the highest quantum yield ≈20%. Moreover, such kind of fluorescent SCNPs manifest low cytotoxicity and good cell imaging performance for Hela cells. The creation of fluorescent SCNPs through covalently attached one quasi-chromophore to the end of one fluorinated zwitterionic random copolymer provides an alternative strategy for preparing polymeric luminescence nanomaterials, promisingly serving as a new type of fluorescent nanoprobes for biological imaging applications.

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study.

We theoretically analyze possible multiple conformations of protein molecules immobilized by 1-pyrenebutanoic acid succinimidyl ester (PASE) linkers on graphene. The activation barrier between two bi-stable conformations exhibited by PASE is confirmed to be based on the steric hindrance effect between a hydrogen on the pyrene group and a hydrogen on the alkyl group of this molecule. Even after the protein is supplemented, this steric hindrance effect remains if the local structure of the linker consisting of an alkyl group and a pyrene group is maintained. Therefore, it is likely that the kinetic behavior of a protein immobilized with a single PASE linker exhibits an activation barrier-type energy surface between the bi-stable conformations on graphene. We discuss the expected protein sensors when this type of energy surface appears and provide a guideline for improving the sensitivity, especially as an oscillator-type biosensor.

Unveiling the Activity and Mechanism Alterations by Pyrene Decoration on a Co(II) Macrocyclic Catalyst for CO2 Reduction.

Mechanistic studies involving characterization of crucial intermediates are desirable for rational optimization of molecular catalysts toward CO2 reduction, while fundamental challenges are associated with such studies. Herein we present the systematic mechanistic investigations on a pyrene-appended CoII macrocyclic catalyst in comparison with its pyrene-free prototype. The comparative results also verify the reasons of the higher catalytic activity of the pyrene-tethered catalyst in noble-metal-free CO2 photoreduction with various photosensitizers, where a remarkable apparent quantum yield of 36±3 % at 425 nm can be obtained for selective CO production. Electrochemical and spectroelectrochemical studies in conjunction with DFT calculations between the two catalysts have characterized the key CO-bound intermediates and revealed their different CO-binding behavior, demonstrating that the pyrene group endows the corresponding CoII catalyst a lower catalytic potential, a higher stability, and a greater ease in CO release, all of which contribute to its better performance.

Photophysicochemical and electrochemical properties of pyrene–BODIPY platforms

The photochemical, photophysical, and electrochemical properties of novel BODIPY compounds substituted with iodine or pyrene groups at the 2-, 6-, or 8-positions (meso) were thoroughly investigated.

Enhancing Photoredox Catalysis in Aqueous Environments: Ruthenium Aqua Complex Derivatization of Graphene Oxide and Graphite Rods for Efficient Visible-Light-Driven Hybrid Catalysts.

A ruthenium aqua photoredox catalyst has been successfully heterogeneneized on graphene oxide (GO@trans-fac-3) and graphite rods (GR@trans-fac-3) for the first time and have proven to be sustainable and easily reusable systems for the photooxidation of alcohols in water, in mild and green conditions. We report here the synthesis and total characterization of two Ru(II)-polypyridyl complexes, the chlorido trans-fac-[RuCl(bpea-pyrene)(bpy)](PF6) (trans-fac-2) and the aqua trans-fac-[Ru(bpea-pyrene)(bpy)OH2](PF6)2 (trans-fac-3), both containing the N-tridentate, 1-[bis(pyridine-2-ylmethyl)amino]methylpyrene (bpea-pyrene), and 2,2'-bipyridine (bpy) ligands. In both complexes, only a single isomer, the trans-fac, has been detected in solution and in the solid state. The aqua complex trans-fac-3 displays bielectronic redox processes in water, assigned to the Ru(IV/II) couple. The trans-fac-3 complex has been heterogenized on different types of supports, (i) on graphene oxide (GO) through π-stacking interactions between the pyrene group of the bpea-pyrene ligand and the GO and (ii) both on glassy carbon electrodes (GC) and on graphite rods (GR) through oxidative electropolymerization of the pyrene group, which yield stable heterogeneous photoredox catalysts. GO@trans-fac-3- and GR/poly trans-fac-3-modified electrodes were fully characterized by spectroscopic and electrochemical methods. Trans-fac-3 and GO@trans-fac-3 photocatalysts (without a photosensitizer) showed good catalytic efficiency in the photooxidation of alcohols in water under mild conditions and using visible light. Both photocatalysts display high selectivity values (>99%) even for primary alcohols in accordance with the presence of two-electron transfer processes (2e-/2H+). GO@trans-fac-3 keeps intact its homogeneous catalytic properties but shows an enhancement in yields. GO@trans-fac-3 can be easily recycled by filtration and reused for up to five runs without any significant loss of catalytic activity. Graphite rods (GR@trans-fac-3) were also evaluated as heterogeneous photoredox catalysts showing high turnover numbers (TON) and selectivity values.

Effect of Ligand Aromaticity on Cyclohexane and Benzene Sorption in IRMOFs: A Computational Study.

A series of four isoreticular MOFs (IRMOF-1, -10, -14, and -16) were selected for a computational investigation of the effect of ligand aromaticity on the adsorption capacity of an aromatic VOC (benzene) compared to its nonaromatic analog (cyclohexane). The affinity of the adsorbates was evaluated by calculating Henry's constants and adsorption enthalpies. It has been evidenced that while KH values decrease with ligand elongation (IRMOF-10 and -16), inserting a pyrene core into the MOF structure (IRMOF-14) increases both the cyclohexane and benzene adsorption efficiency by ∼290 and 54%, respectively. To elucidate host-guest interactions, we sought to locate preferential adsorption sites in MOF structures for the two VOCs studied by using the GCMC method. It appears that benzene interacts with the metal center (Zn4O clusters) and most of the ligand while cyclohexane tends to localize preferentially only near the Zn4O clusters. Coadsorption isotherms (equimolar mixture of benzene and cyclohexane) demonstrated the preferential adsorption of cyclohexane due to the stronger affinity for the MOF structure. On the other hand, for other isoreticular structures, the ligand elongation leads to a shift of the adsorption curve of cyclohexane caused by pore size increase and therefore less interactions with the walls. This phenomenon is counterbalanced in the case of IRMOF-14 due to stronger interactions between the cyclohexane and pyrene groups. The present results thus open perspectives in the design of promising MOF candidates for high-performing separation and sorption/detection of hydrocarbon VOCs.

Synthesis of pyrene and pyrrole-appended fluorescent turn-off sensor toward Cr(VI) detection: Chemical oxidative and electrochemical polymerization of carboxamide

A carboxylic amide compound containing pyrrole and pyrene groups, referred to as PP, was synthesized and characterized for its structural, optical, and electrochemical properties. Upon excitation with 320 nm light, PP displayed blue emission at 387 nm, which was found to be quenched due to chelate formation in the presence of Cr(VI). Conducted competition experiments involving chloride salts of Ag+, Al3+, Cd2+, Co2+, Cr3+, Fe3+, Hg2+, K+, Mn2+, Ni2+, Pb2+, Sn2+, and Zn2+ demonstrated the notable selectivity of compoundPP towards Cr(VI)ions. This selectivity was evidenced by a pronounced turn-off fluorescent effect, attributed to a chelation-enhanced quenching (CHEQ) mechanism by the formation of 1:2 chelation between Cr(VI) and the ligand PP. Moreover, addition of EDTA toPP– Cr(VI)chelation recovered the fluorescence offering receptorPPas a reversible sensor. The PP probe demonstrated remarkable selectivity in detection Cr(VI)ions among various metallic ions, displaying a limit of detection (LOD) value of 0.106 µM. Chemical oxidative and electropolymerization methods were employed to synthesize two distinct polymers, namely Poly(PP)-O and Poly(PP)-E, respectively. The electropolymerization of PP was carried out in 0.1 M TBAF6P serving as a supporting electrolyte solution, while oxidative polymerization was conducted in the presence of FeCl3. Mass average molecular weight of the oxidative polymerization product was 5200 Da, as determined by GPC analysis. Thermal characterization was performed via TG-DTA-DTG curves. The electropolymerization product of PP coated on the ITO surface was further characterized by SEM.

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di‐(N‐Heterocyclic Carbene) Building Blocks

AbstractA series of [2]catenanes has been prepared from di‐NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn‐[1] and the kinked biphenyl‐bridged bipyridyl ligand L2 yield the [2]catenane [2‐IL](OTf)4 by self‐assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl‐linker in L2 for a pyromellitic diimide group gave ligand L3, which yielded in combination with syn‐[1] the [2]catenane [3‐IL](OTf)4. This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L4. Di‐NHC precursor H2‐L4(PF6)2 reacts with Ag2O to give the [Ag2L42]2 [2]catenane [4‐IL](PF6)4, which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au2L42]2 gold species [5‐IL](PF6)4, which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au‐CNHC bonds.

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di-(N-Heterocyclic Carbene) Building Blocks.

A series of [2]catenanes has been prepared from di-NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn-[1] and the kinked biphenyl-bridged bipyridyl ligand L2 yield the [2]catenane [2-IL](OTf)4 by self-assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl-linker in L2 for a pyromellitic diimide group gave ligand L3 , which yielded in combination with syn-[1] the [2]catenane [3-IL](OTf)4 . This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L4 . Di-NHC precursor H2 -L4 (PF6 )2 reacts with Ag2 O to give the [Ag2 L4 2 ]2 [2]catenane [4-IL](PF6 )4 , which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au2 L4 2 ]2 gold species [5-IL](PF6 )4 , which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au-CNHC bonds.

Characterizing the Non-Covalent Binding of a Pyrene-Derived Linker for DNA Immobilization on Graphene Field-Effect Transistors

Graphene field-effect transistors (G-FETs) constitute an emerging platform for biosensing applications. Most genomic applications with G-FETs use single-stranded DNA (ssDNA) as probes in order to capture a specific target DNA sequence and to detect the corresponding change in the electrical response of the sensor1. Controlling the distribution of DNA probes on the graphene surface is crucial to the sensitivity, selectivity and reproducibility of the sensors1. The most popular immobilization approach uses a non-covalent linker molecule named 1-pyrenebutanoic acid succinimidyl ester (PBASE)1. This bifunctional molecule binds to the graphene surface through non-covalent π-π interactions via its aromatic pyrene group, and on the other end, its succinimidyl ester group can form a covalent bond with amine groups added to the terminal end of ssDNA probes. However, the adsorption process of PBASE molecules is not well controlled, which represents a limitation in the optimization of G-FET biosensors.Here, we present an investigation of the kinetics of the non-covalent adsorption of PBASE on graphene, in order to control the density of ssDNA probes for biosensing applications with G-FETs. We fabricated G-FET sensor arrays using CVD-grown graphene and photolithography techniques, as described previously2. First, we investigated the effect of incubation time on PBASE coverage on graphene, using electrical curves as well as Raman hyperspectral imaging (RIMA). We report a significative and reproducible electrical signature for the PBASE compared to the control without PBASE. We find that this electrical signature appears and saturates quickly compared to the timescales usually reported in the literature. Corroborating results were obtained with RIMA spectroscopy, showing a rapid response of the graphene modes following PBASE incubation. Next, we studied the effect of PBASE accumulation on the assembly of ssDNA probes. We will discuss the combined effect of PBASE accumulation and screening effects in saline buffer on the electrical signature of ssDNA probes. Our results will enable a better control on the non-covalent functionalization of graphene with PBASE for the assembly of various biomolecular probes for biosensing applications.1. Béraud A, Sauvage M, Bazan CM, Tie M, Bencherif A, Bouilly D. Graphene field-effect transistors as bioanalytical sensors: design, operation and performance. Analyst. 2021;(146):403-428.2.Bazan CM, Béraud A, Nguyen M, Bencherif A, Martel R and Bouilly D. Dynamic Gate controlled of Aryldiazonium chemistry on Graphene field-effect transistors. Nano Lett. 2022;22(7):2635-2642.

Fluorescent Materials Containing Polycyclic Aromatic Compounds: synthesis, Fluorimetric Detection of Nitroaromatic Compounds and Color Properties

Schiff bases with pyrene, anthracene or naphthalene groups can act as simple, sensitive, and selective sensors for the detection of trace explosives. We have prepared three new types of Schiff bases with fluorescent properties as fluorescent probes for use in the fluorescence detection of explosives. The detection properties of the synthesized compounds of photophysical and fluorescent explosives were investigated. Spectroscopic methods were used for the structural characterization of the compounds. Within the scope of the study, compounds (A, B and C) were used as fluorescent probes in the detection of some explosives and the data obtained were recorded. Instead of the quenching effect expected by the explosives on the emissions of the compounds, it was observed in some experiments that the emission intensity due to aggregation increased. In addition, the color measurements (CIE standards) and Color temperature (CCT) of the compounds were calculated.

Synthesis and properties of acyldiphenylphosphine oxides photoinitiators carrying triphenylamine or pyrene group for free radical photopolymerization

AbstractTwo new photoinitiators of acyldiphenylphosphine oxides carrying triphenylamine (NHPO) or pyrene group (BHPO) were designed and synthesized with diphenylphosphine oxide reacting with 4‐(diphenylamino) benzaldehyde or 1‐pyrenecarboxaldehyde. The solubility of NHPO is about 13.7 wt% in TMPTA, which is higher than that of (2,4,6‐trimethylbenzoyl) diphenylphosphine oxide (TPO) (about 12.5 wt%). The UV–Vis spectrum of NHPO and BHPO revealed that their maximum absorption wavelengths have redshifted to 397 and 419 nm, respectively, with a molar extinction coefficient of around 19,057 and 24,257 M−1 cm−1, suggesting that they are likely to be effective photoinitiators when exposed to light from LEDs. According to real‐time Fourier transform infrared spectroscopies, the degree of double bond conversion of NHPO reached 65%, which was higher than that of TPO (about 45%), showing that NHPO had substantially better photoinitiated properties than TPO. Using steady‐state photolysis and electron spin resonance spin‐trapping studies, the photocuring mechanism was examined, and it was discovered that the NHPO and BHPO had produced two free radicals. Additionally, NHPO exhibited superior biocompatibility performance as demonstrated by cytotoxicity assays and had a low migration rate of only 0.23%, as determined by migration. As a result, NHPO might be utilized in coatings for food packaging.

Preparation and fluorescence performance of high elastic core-shell structure composite fibers based on electrospun nanofibers

Fluorescent fibers with light weight and good mechanical properties provide exciting opportunities for the development of flexible optical sensing textiles. This could accelerate the realization of the wearable technology goal of functional and large area display. Here, we synthesized a polyimide containing 20% pyrene group (Py-20) with excellent fluorescence and thermal properties. Then, fluorescent composite fibers with core–shell structure were prepared by using Py-20 electrospun membrane as surface layer and polyurethane (TPU) fiber as inner layer. The diameter and thickness of surface fluorescent fibers was 500 nm and 100 μm, respectively. Polarized infrared spectra analysis proved that the aggregation of polymer molecular chains in electrospun fiber could be reduced effectively. The DR (DR = I∥/I⊥) values of polymer film and electrospun fibers were 0.7553 and 0.5955, respectively. Therefore, the fiber samples exhibited higher fluorescence intensity than the polymer film. The maximum photoluminescence peaks of electrospun and composite fibers were located at about 595 nm. In addition, thanks to interlaced layered structure of electrospun fibers, the fluorescent composite fiber maintained a relatively uniform morphology at 40.84% (strain) and 4.96 MPa (stress). Importantly, this Py-20/TPU composite fiber could meet the complex weaving process of yarns and display bright yellow-orange colors under ultraviolet light irradiation. Thermal analysis exhibited that the initial decomposition temperature (Td) of composite fiber in the air could reach to 269 °C. This fiber material will become a competitive candidate in smart textiles with the excellent luminescence, mechanical and thermal properties.

Visualizing mitochondrial viscosity during ferroptosis by using a solvatochromic effect-decreased hemicyanine probe

Because the vinyl-bridged donor-π-acceptor (D-π-A) structure of hemicyanine dye is very sensitive to the change of microenvironmental viscocity, they were applied for measurement of viscosity change in living cells. As the optical properties of most reported hemicyanine derivatives were strongly influenced by the solvent-sensitive amino group or hydroxyl group within the fluorophore, the design of hemicyanine dye with weak solvent effect for monitoring the change of viscosity in living cells is valuable. Herein, we developed a pyrene- and dehydropyridocolinium-containing fluorescent probe PyQz for monitoring the change of viscosity in mitochondria during ferroptosis process. As the probe using a pyrene group without a solvent-sensitive amino group or hydroxyl group as the electron donor and a dehydropyridocolinium as a electron acceptor, compared to many hemicyanine dyes the probe showed an obviously decreased solvatochromic effect and good chemical stability. The probe exhibited a good stability, ca. 25-fold enhancement in response to 95% glycerol, fast response time (<10 s) and excellent mitochondrial targeting ability (Pearson’s correlation coefficient 0.98).