Aggregation‐induced enhanced emission for quantification of recycled content in automotive plastics

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This manuscript describes the preparation of water soluble aggregation-induced emission enhancement (AIEE)-based fluorescent organic nanoparticles (FONs). The fluorescence diversity of the FONs was investigated in the presence of silver nanowires. We observed that the emission of the FONs can be enhanced by mixing with the nanowires, which is believed to originate from resonance between the emission of the FONs and the surface plasmon resonances of the metal surface. That is, the AIEE phenomenon was promoted according to the metal-enhanced fluorescence (MEF) mechanism that can be used to build up a novel double emission enhancement (DEE) platform and to extend the range of AIEE applications. The systemic fluorescence enhancement, lifetime and photostability were measured and the AIEE-MEF evaluation and the interaction between the FONs and nanowires were discussed based on the obtained spectral data and SEM and fluorescent microscopy images.

We report for the very first time the crystal structure and self-assembly of a new aggregation-induced emission enhancement (AIEE) dye 4-(5-methoxythiazolo[4,5-b]pyridin-2-yl)-N,N-dimethylaniline (TPA) and its application in sensing dichromate ions. TPA reveals cyan blue emission under UV and visible light. The self-assembly properties of TPA were studied extensively by scanning electron microscopy (SEM) which revealed the formation of beautiful flower-like morphologies. These structures revealed both green and red fluorescence under FITC and rhodamine filters respectively when observed through fluorescence microscopy connoting the panchromatic emission properties of TPA from blue to red. The interactions which cause self-assembled structure formation in TPA were also validated theoretically using density functional theory (DFT) calculations. Crystal and molecular structure analysis of TPA was carried out via single-crystal X-ray diffraction to visualize the intermolecular interactions occurring in the solid-state and to study the structure-photophysical property relationship in the aggregated state. The photophysical properties of TPA were also studied extensively by UV-visible and fluorescence spectroscopy and its quantum yield and fluorescence lifetime were calculated by time-correlated single-photon counting (TCSPC). Interestingly, TPA could efficiently sense dichromate (Cr2O72-) ions in an acidic medium and an interesting morphological transition from a fluorescent flower to non-fluorescent disassembled structures could also be observed. The limit of detection of TPA for Cr2O72- ions was found to be as low as 5.5 nM, suggesting its exceptional sensitivity. More importantly, TPA could selectively sense Cr2O72- ions in real water samples even in the presence of other metal ions routinely present in polluted water, hence making it practically useful for water quality monitoring.

A novel fluorescence sensor for successive detection of Cu2+ and Fe3+ based on anti-B18H22 derivative which possesses 5-hydroxyisoquinoline as an ionophore was synthesized via a one-pot and its structure and photophysical properties were characterized by NMR, HRMS, FTIR, UV–vis, PL and theoretical calculation. The fluorophore displays two emission peaks at 460 nm and 670 nm in THF solution coming from the emission of the locally excited state and intramolecular charge transfer fluorescence, respectively. The complex exhibited obvious aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O solution by increasing the aqueous concentration from 70% to 95%. The AIEE molecules showed a high selectivity towards Cu2+ over other metal ions by forming a 2:1 metal-to-ligand complex in THF/H2O (fw = 20%) solution, the fluorescence intensity increased as a linear function of the Cu2+ concentration at 460 nm due to the inhibition of PET effect. The fluorescent emission was quenched linearly by the addition of Fe3+, which provides a method for successive determination of Cu2+ and Fe3+ based on ‘off-on-off’ fluorescence of the fluorescent. The detection limit of Cu2+ and Fe3+ was 5.7 × 10−6 M and 7.2 × 10−5 M respectively. Morever, a rapid identification of Cu2+ in the aqueous solution by naked eyes can be realized. In addition, the molecules were pH-sensitive, the fluorescence quenching can be observed in strongly alkaline environment. The method has been applied to the determination of copper ions in water samples with satisfactory results.

Multiple‐resonance (MR) thermal activated delayed fluorescence (TADF) emitters have attracted increasing attention in organic electroluminescence devices, owing to their superior quantum efficiency and narrowband emission for high color purity. However, MR‐TADF materials often suffer from severe aggregation‐caused quenching (ACQ) and efficiency roll‐off problems due to their rigid planar structures and the lack of sufficient charge‐transfer (CT) characters with inefficient reverse intersystem crossing (RISC). Herein, by attaching electron‐rich triphenylamine (TPA) with twisted spatial conformation to the MR framework, two efficient narrowband MR‐TADF emitters, namely BNCz‐pTPA and BNCz‐mTPA, are developed. The TPA substituent endows the new emitters with aggregation‐induced emission enhancement (AIEE) for ACQ suppression. The unprecedented AIEE‐MR‐TADF emitters exhibit CT character in high‐lying triplet excited states for faster RISC, while the locally‐excited (LE) character of the first singlet excited state is retained for narrowband emission with high emission efficiency. An organic light‐emitting diode (OLED) based on BNCz‐pTPA exhibits a maximum external quantum efficiency of 27.3% with slow efficiency roll‐off, demonstrating much higher performances than those of the BNCz‐based OLED. This study may provide a simple but effective approach to constructing high‐performance emitters for wide‐color‐gamut OLED displays.

We present spatiotemporal control of aggregation-induced emission enhancement (AIEE) of a protonated tetraphenylethene derivative by optical manipulation. A single submicrometer-sized aggregate is initially confined by laser irradiation when its fluorescence is hardly detectable. The continuous irradiation of the formed aggregate leads to sudden and rapid growth, resulting in bright yellow fluorescence emission. The fluorescence intensity at the peak wavelength of 540 nm is tremendously enhanced with growth, meaning that AIEE is activated by optical manipulation. Amazingly, the switching on/off of the activation of AIEE is arbitrarily controlled by alternating the laser power. This result means that optical manipulation increases the local concentration, which overcomes the electrostatic repulsion between the protonated molecules, namely, optical manipulation changes the aggregate structure. The dynamics and mechanism in AIEE controlled by optical manipulation will be discussed from the viewpoint of molecular conformation and association depending on the laser power.

Polymer-assisted sol–gel synthesis and characterization of Zn 2SiO 4:Eu 3+ powders

A tetraphenylethylene (TPE) derivative, TPEPhDAT, modified by diaminotriazine (DAT), was prepared by successive Suzuki-Miyaura coupling and ring-closing reactions. This compound exhibits aggregation-induced emission enhancement (AIEE) properties in the DMSO/MeOH system, with a fluorescence emission intensity in the aggregated state that is 5-fold higher than that of its counterpart in a dilute solution. Moreover, the DAT structure of the molecule is a good acceptor of protons; thus, the TPEPhDAT molecule exhibits acid-responsive fluorescence. TPEPhDAT was protonated by trifluoroacetic acid (TFA), leading to fluorescence quenching, which was reversibly restored by treatment with ammonia (on-off switch). Time-dependent density functional theory (TDDFT) computational studies have shown that protonation enhances the electron-withdrawing capacity of the triazine nucleus and reduces the bandgap. The protonated TPEPhDAT conformation became more distorted, and the fluorescence lifetime was attenuated, which may have produced a twisted intramolecular charge transfer (TICT) effect, leading to fluorescence redshift and quenching. MeOH can easily remove the protonated TPEPhDAT, and this acid-induced discoloration and erasable property can be applied in anti-counterfeiting.

A novel mechanoresponsive and solvatochromic luminescentcompound(MO-HBI) was designed by combining an ESIPT-activedonor with a benzophenone acceptor, exhibiting reversible luminescenceswitching and aggregation-induced emission enhancement. The solvatochromicbehavior of MO-HBI was systematically studiedin solvents of varying polarity, revealing a distinct bathochromicshift in both absorption and fluorescence emission, with pronouncedsensitivity attributed to the presence of a carbonyl group. Upon mechanicalstimulation, MO-HBI undergoes a crystalline-to-amorphousphase transition, leading to a significant fluorescence increase andcolor change from faint yellow to yellow-green. Structural analysisand DFT computation confirm that mechanoresponsive property originatesfrom disrupted intermolecular hydrogen bonding and altered molecularpacking. The emission can be fully recovered through solvent fumingor thermal annealing. Based on this, a rewritable optical storagesystem was developed using MO-HBI coatedpaper, allowing erasable data display triggered by mechanical andvapor stimuli. This study provides a promising strategy for designinghigh-contrast, reversible mechanoresponsive systems for sensing andinformation storage applications.

The CO2 emission regulations have an increasing impact on the automotive industry, as these regulations are connected with severe penalties in case the average fleet emission is exceeding the limits for Europe, as imposed by the European Commission. These measures are enforcing the automotive industry to a significant increase in fuel efficiency. Basically, the emissions can be reduced, by reducing the wear losses in the powertrain and by reducing the weight of the cars, by using more and more plastic materials. Many of these parts do also have a decorative function and therefor are Chrome plated. As the plating process has to handle heavy poisoning liquids and consumes a lot of water, the industry is looking for green low cost alternatives. In this chapter the Cromatipic® process is introduced which combines a painting with a PVD coating and fulfils all requirements of the automotive industry for interior and exterior decorative parts. Finally will be introduced an integrated inline factory for performing the Cromatipic® process very cost effective.

A new kind of low molecular-mass organic gelator (LMOG) π-electron-deficient N,N-octyl-7,7'-diazaisoindigo (1) with aggregation-induced enhanced emission (AIEE) phenomenon is described. This organogel is capable of self-assembling through intermolecular H-bonding and π−π interactions between diazaisoindigo molecules. Its rheological properties, X-ray diffraction pattern, optical properties and theoretical calculations were investigated. The AIEE effect is exhibited in fluorescence during the formation of the supramolecular organogel, which persisted in the xerogel state, the spectral red-shifts suggest the formation of J-type aggregates during the gelation process via - interactions in microbelts or 3D networks. Fluorescence lifetime and quantum yield significantly increases from dilute solution to the aggregate state. From a theoretical perspective, the effect of the aggregation of 1 on the photophysical properties was also studied by means of the Density Functional Theory (DFT). In this sense, the low...

A novel highly selective probe with both aggregation-induced emission enhancement and intramolecular charge transfer characteristics for CN− detection

Water Dynamics of a Model Protein Phase Separation via Fluorescence Lifetime and Spectral Analysis of ACDAN

Three Eu(III) complexes, named DDA-Eu-7, DDI-Eu-7, and DDE-Eu-7, are constructed by dehydroabietyl imidazoline, ethyl aminoimidazole dehydroabietyl imidazoline, and ethyl esterimidazole dehydroabietyl imidazoline units, respectively. The coordinate structures of three Eu(III) complexes are characterized by FTIR, UV-vis, TG/DTG, ESI-MS, WAXD, elemental analysis, and XPS measurements. Among three Eu(III) complexes, DDA-Eu-7 exhibits the highest fluorescence lifetime (537.46 μM), the largest absolute quantum yield (54.84%), and the narrowest FWHM of 5D0→7F2 transition (5.9 nm). Due to the coordinate structure with high electric diploe and ligand polarization induced by more imidazole groups, DDA-Eu-7 exhibits more Stark-splitting emission peaks than those of DDI-Eu-7 and DDE-Eu-7. The results of fluorescence emission and the Judd–Ofelt parameters indicate that DDA-Eu-7 demonstrates the highest asymmetry of the coordinate structure. The fluorescence quenching ability of haloacetic acids on DDA-Eu-7 is in the order of iodoacetic acid > bromoacetic acid > chloroacetic acid. The analysis of fluorescence spectra and fluorescence lifetime verify that the quenching process of DDA-Eu-7 induced by iodoacetic acid conforms to the dynamic quenching model with the limit of detection of 2.31 μM, whereas the quenching processes invoked by chloroacetic acid and bromoacetic acid are in accord with the mixed quenching model including static and quenching models.

Cash-hungry managers versus real-world sustainability. Is this the case in the automotive plastics and recycling industry? To find out, a survey was conducted throughout Europe covering all the key players, ranging from virgin plastics producers, automotive industries including OEMs and suppliers, shredders, and recyclers as well as research institutions. In this chapter, the survey results are outlined and cross-checked with the results of the experts workshop. By doing so, quantitative data from the survey is merged with qualitative data from the workshops increasing the real-world representation. This approach enables the investigation of the reasons for the insufficient implementation of recycling in the car life-cycle as outlined in the previous chapters, and to ultimately provide solutions to advance the circular economy of automotive plastics.