Molecular Systems Design & Engineering最新文献

It is extremely challenging to design external stimuli-controlled molecular switches with absorption and fluorescence dual-mode outputs that are suited for diverse states. Herein, we propose a general molecular design strategy for achieving fluoride-regulated colorimetric and fluorometric switches based on B–F dynamic covalent reactions by introducing borate units into AIE-active molecular skeletons. A group of fluoride-responsive smart molecules was designed by introducing one or two borate units into the typical aggregation-induced emission molecular skeleton tetraphenylethene, all of which can be combined with fluoride ions to form stable products with sharp color and fluorescence changes. It is proved that the addition of fluoride ions onto the boron center can regulate the photophysical behaviour of these compounds, and the AIE activity of these compounds enables them to perform well in a solid matrix, which is more desirable in diverse practical applications. Their fluoride-responsive photophysical behaviour and AIE activity provide an opportunity to develop a quantitative detection method for fluoride ions with high selectivity and high sensitivity both in solution and on a solid matrix-like test strip, which greatly simplifies the recognition of fluoride ions. The dynamic nature of the B–F covalent reaction and the multicolor switching behaviour of these smart molecules was demonstrated in controllable colorful patterning and advanced data encryption with excellent performance. This study highlights that the combination of the B–F dynamic covalent reaction and the AIEgens can greatly expand fluoride-responsive smart molecules from only solution-based fluoride sensing to diverse surface/interface-involved applications in dual-mode signaling.

The development of polymeric materials with switchable properties upon exposure to external stimuli such as light, heat, force, acids/bases, and chemicals has attracted much attention due to their potential applications in smart coatings, drug carriers, soft robotics, etc. Thus, a systematic understanding of the relationship between the chemical structures and stimuli-responsive properties as well as the corresponding mechanisms of switchable stimuli-responsive polymers is important to guide the sophisticated design of functional macromolecules for specific applications. In this review, we outline the representative chemical structures that enable reversible structural switching to be achieved under photo-, mechano-, CO₂- and chemo-stimuli, with a brief discussion on thermo- and pH-activation. Polymer materials containing these chemical moieties exhibit unique behaviours on changing their mechanical, thermal or photochemical property in a switchable manner, and their applications in healing materials, rewritable surfaces, drug delivery carriers, conductive hydrogels and luminescent materials are highlighted. Based on the comprehensive summary of structural switchable moieties and applications of polymer materials, this review gives insight into how bottom-up approaches can be used to inspire the future design of switchable multi-stimuli-responsive polymer materials.

The state-of-the-art organic composite nanofibers have certain advantages over their metal-oxide counterparts because of mechanical flexibility, lightweightness and electrical conductivity. This study focuses on the synthesis of a novel styrene–butadiene–styrene (SBS) copolymer blended with polystyrene (PStyr) and carbon nanotubes (CNTs), and its properties are compared with CNT-free versions as well as with polystyrene–polybutadiene blends. The semi-crystallinity of SBS/PStyr disappears with the inclusion of CNTs of 1.25 wt%, indicating that even small quantities of CNTs retard the crystallization process. In Fourier transform infrared spectroscopy, the included CNTs reveal themselves by the decreased absorbance of both SBS/PStyr and PStyr/PBu. On the other hand, for Raman spectroscopy, this intensity drop is only recognizable in PStyr/PBu, where the interaction of CNTs with PStyr and PBu was limited in samples with SBS. PStyr/PBu/CNT has a non-porous and rough texture, and it is relatively denser with a mean fiber diameter of 0.66 μm compared to its CNT-free counterpart. The glass transition (T_g) of the PBu peak is determined to be changing between ?96 and ?72 °C, whereas the T_g of polystyrene is not majorly influenced by copolymerization nor by CNT addition. The observed changes are accounted for by the increase in C1s sp² and decrease in C1s C–O, CO and OCO peaks upon CNT addition, particularly for SBS/PStyr.

Although high color purity and efficient organic light-emitting devices (OLEDs) are imperative for high-resolution display applications, the stability of these OLEDs lags far behind that of OLEDs based on conventional thermally activated delayed fluorescent and/or phosphorescent emitters. In this work, using a BODIPY derivative, we successfully developed a high-efficiency, long-lifetime green OLED with high color purity. Based on sophisticated device engineering especially by reducing carrier accumulation at the hole-transporter/emission layer interface, the optimized device realized a narrow full width at half maximum of 32 nm, CIE coordinates of (0.28, 0.67), external quantum efficiency of approximately 19%, and lifetime (LT₅₀) of 14?000 h at 1000 cd m^?2. The device stability was 4.7 times longer than that in the previous work, and among the best reported in the related literature.

High-spin ground-state polyradicals are an important platform due to their potential applications in magnetic and spintronic devices. However, a low high-to-low spin energy gap limits the population of the high-spin state, precluding their application at room temperature. Also, design strategies delineating control of the ground electronic state from a closed-shell low-spin to open-shell polyradical character with a high-spin ground state are not well established. Here, we report indacenodinaphthothiophene isomers fused with a 6,6-dicyanofulvene group showing a high-spin quintet ground state. Density functional theory calculations indicate that the syn- and anti-configurations have a closed-shell low-spin singlet ground state. However, the linear-configuration displays a high-spin quintet ground state, with the energy difference between the high-spin quintet to the nearest low-spin excited states calculated to be as large as 0.24 eV (≈5.60 kcal mol^?1), exhibiting an exclusive population of the high-spin quintet state at room temperature. These molecules are compelling synthetic targets for use in magnetic and spintronic applications.

Metal–organic frameworks (MOFs) combining both organic and inorganic redox-active moieties have recently drawn interest in the field of electrochemical energy storage. Here we focused our attention on MIL-53(M) (M = Al, Fe) analogues based on 2,5-dioxo-1,4-benzenedicarboxylate, as this ligand was already found to present an interesting electrochemical activity based on the quinone/phenolate redox couple in the solid state. We described here our attempts to chemically lithiate the title solids. Various synthetic paths were explored, and the resulting solids were characterized by a broad set of techniques, including X-ray diffraction, MAS NMR spectroscopy, transmission electron microscopy, inductively coupled plasma-atomic emission spectroscopy and total X-ray scattering experiments, among others. We showed that although the lithiation was accompanied by a loss of the long-range order whatever the synthetic conditions and the trivalent cation, the reactivity strongly differed for M = Al and Fe. Eventually, the electrochemical extraction/uptake of Li⁺ in the lithiated derivatives was evaluated in Li-half cells. Although their storage capacities are moderate, we found that the presence of even a minor amount of M³⁺ cations not only impacts the working potential of the ligand but also improves their long term capacity retention.

Consistent progress in therapeutics is important to overcome the emerging challenges in human health and diseases. Nano/microrobots are one of the most advanced types of nano/microscale particles with self-propagating ability, and have significantly addressed human health related challenges. These nano/microrobots are the combinational outcomes of technology with nanoscience, and piqued the interest of many researchers worldwide. The most notable achievement in this field is active targeting and on-demand controlled motion of nano/microrobots, reducing the driving time in the circulatory system and off-target accumulation, which is difficult to achieve in traditional drug delivery systems. Our discussion in the review includes fabrication processes, actuation mechanisms of DNA, magnetic force driven and light driven nano/microrobots, and their applications in various disease theranostics. Finally, we concluded with the advantages of nano/microrobots over conventional nano/microparticles and their limitations and future prospects.

When immobilised on a suitable electrode surface, metal organic frameworks (MOFs) can effectively promote the oxygen evolution reaction (OER) – the anode process of water electrolysis for the green hydrogen synthesis – most commonly through the electrooxidative decomposition of the framework into thermodynamically stable (oxy)hydroxides/oxides. In this study, the potential advantageous electrocatalytic effect of the macrocyclic amine core coordinating to the cobalt ions in an interdigitating 2D sheet framework is investigated. Nickel foam electrodes modified with Co-TMBT-MOF at a low loading of 0.25 mg cm^?2 (0.004 mmol_Co cm^?2) sustained the OER rate of 20 mA cm^?2 (80 A g_MOF^?1) in 1 M KOH at ambient temperature at a stabilised overpotential of only 0.294 ± 0.005 V on a timescale of 20 h. Physical characterisation of the electrode after the OER tests confirmed transformation of the MOF into the catalytically active cobalt oxyhydroxide.

Due to the rising scarcity of clean water in arid climates, there is an increased relevance in accessing clean and renewable water resources. One such perspective method, sorption-based atmospheric water harvesting, collects atmospheric water as an alternative to ground and surface water. Metal–organic frameworks (MOFs) are proposed as excellent porous materials for the capture and storage of small molecules, including water, owing to their large pore volume, high surface area, and chemical and structural tunability. Here a zwitterionic MOF (Ni-ZW-MOF), [Ni(dcpb)(H₂O)₄·14H₂O]_n, was synthesized and studied for its water sorption performance, displaying selective water adsorption and desorption capabilities. Respective sorption properties were tested in controlled low and high humidity environments over multiple cycles, demonstrating its regenerative ability and high working capacity (126.4 mL kg^?1 per cycle).