Motorized Photomodulator: Making A Non-photoresponsive Supramolecular Gel Switchable by Light.

Introducing photo-responsive molecules offers an attractive approach for remote and selective control and dynamic manipulation of material properties. However, it remains highly challenging how to use a minimal amount of photo-responsive units to optically modulate materials that are inherently inert to light irradiation. Here we show the application of a light-driven rotary molecular motor as a "motorized photo-modulator" to endow a typical H-bond-based gel system with the ability to respond to light irradiation and create a reversible sol-gel transition. The key molecular design feature is the introduction of a minimal amount (2 mol %) of molecular motors into the supramolecular network as photo-switchable non-covalent crosslinkers. Advantage is taken of the subtle interplay of the large geometry change during photo-isomerization of the molecular motor guest and the dynamic nature of a supramolecular gel host system. As a result, a tiny amount of molecular motors is enough to switch the mechanical modulus of the entire supramolecular systems. This study proves the concept of designing photo-responsive materials with minimum use of non-covalent light-absorbing units.

Hysteresis Nanoarchitectonics with Chiral Gel Fibers and Achiral Gold Nanospheres for Reversible Chiral Inversion.

Intelligent control over the handedness of circular dichroism (CD) is of special significance in self-organized biological and artificial systems. Herein, we report a chiral organic molecule (R1) containing a disulfide unit self-assembles into M-type helical fibers gels, which undergoes chirality inversion by incorporating gold nanospheres due to the formation of Au-S bonds between R1 and gold nanospheres. Upon heating at 80 °C, the aggregation of gold nanospheres results in a disappearance of the Au-S bond, allowing the reversible switching back to M-type helical fibers. The original chirality of M-type fibers could also be retained by adding anisotropic gold nanorods. A series of characterization methods, involving CD, Raman, Infrared spectroscopy, electric microscopy, and small-angle X-ray scattering (SAXS) measurements were used to investigate the mechanism of chiral evolutions. Our results provide a facile way of fabricating hysteresis nanoarchitectonics to achieve dynamic supramolecular chirality using inorganic metallic nanoparticles.

Core Structure Engineering in Hole-Transport Materials to Achieve Highly Efficient Perovskite Solar Cells.

In this work, the thiadiazolopyridine (PT) unit was introduced as the core structure, with N3 ,N3 ,N6 ,N6 -tetrakis(4-methoxyphenyl)-9-phenyl-9 H-carbazole-3,6-diamine as the peripheral group, to obtain a new compound, JY8, for use as a hole-transport material (HTM) in planar perovskite solar cells (PSCs). Compared with the previously reported JY5 with benzothiadiazole as the core structure, the PT unit with stronger electron-withdrawing ability enhanced the intermolecular dipole-dipole interaction. Moreover, the introduction of the PT unit made the central part in JY8 more planar than its analogue JY5, which is conducive to charge transport. Field-emission (FE)-SEM images suggested a smooth and condense morphology of the JY8 film, which could improve the contact between the perovskite layer and the metal electrode. Space-charge limitation of current results, steady-state, and time-resolved photoluminescence decay curves indicated that JY8 as HTM facilitated hole extraction and hole transport. Consequently, planar PSCs fabricated with JY8 as the HTM exhibited a decent efficiency of 19.14 % with a high fill factor of 81 %.

Spontaneously hierarchical self-assembly of nanofibres into fluorescent spherical particles: a leap from organogels to macroscopic solid spheres.

The spontaneous hierarchical self-assembly of organic small molecules into macroscopic architectures with excellent photophysical properties and highly-ordered structures has rarely been reported to date. In this work, we find that the organogel of SY1 formed in ethyl acetate could spontaneously assemble into macroscopic spherical particles with a unique morphology and photophysical properties. Upon increasing the aging time, the gel gradually collapsed and then transformed into many macroscopic spheres (SY1-balls) with an average diameter of ca. 500 µm and strong yellow emission. In view of the emission properties and the porous structure of the SY1-balls, they were successfully applied in the adsorption and detection of heavy metal ions. More interestingly, SY1 shows different assembly behaviours in toluene solution when mixed with a triphenylamine derivative (TPA1). Macroscopic particles (ST-balls) with a core-shell structure were obtained, which were quite different from the SY1-balls in morphology and emission colour. So far as we know, many studies have focused on the change of the micromorphology of a gel, while the spontaneous self-assembly of organogels into macroscopic particles has been reported in this work for the first time. This work enriches the present study on organogels and plays an important role in further understanding the hierarchical self-assembly of organogels.

Toxic Metals Increase Serum Tumor Necrosis Factor-α Levels, Modified by Essential Elements and Different Types of Tumor Necrosis Factor-α Promoter Single-nucleotide Polymorphisms.

BACKGROUND: Lead (Pb), cadmium (Cd), and arsenic (As) could cause health issues through oxidative stress that is indicated in the elevated tumor necrosis factor-alpha (TNF-α). However, some of the essential elements-selenium (Se), zinc (Zn), cobalt (Co), and copper (Cu)-are cofactors or structural components of antioxidant enzymes. It is suggested that single-nucleotide polymorphisms (SNPs) in the TNF-α gene have different TNF-α responses. This study aims to evaluate the effect of serum TNF-α levels through the interactions between toxic metals and essential elements and how the interactions between the toxic metals and TNF-α SNPs (-1031 T > C, -863 C > A, -857 C > T, -308 G > A, -238 G > A) influence serum TNF-α levels. METHODS: Blood samples were collected from 455 workers who carried out annual health examinations and multielements determined by inductively coupled plasma mass spectrometry (ICP-MS). TNF-α levels were detected by enzyme-linked immunosorbent assay (ELISA). TNF-α promoter SNPs were analyzed by specific primer probes using real-time polymerase chain reaction (PCR) methods. RESULTS: Increasing blood Pb, Cd, and As levels were associated with elevated TNF-α levels. The interaction between Pb and Cu decreased TNF-α levels and so did the interaction between Cd and Se. In the interaction between Pb and SNPs, individuals with AA/AG (-308 G > A) and AA/AG (-238 G > A) had higher serum TNF-α levels. However, lower TNF-α levels were noted in those individuals with AA/CA (-863 C > A). In the interaction between As and SNPs, workers with AA/AG (-238 G > A) had synergic effect with As and induced higher serum TNF-α levels. CONCLUSIONS: Blood Cu and Se were antagonists of toxic metals (Pb, As, and Cd) through lower serum TNF-α levels. Variant types of TNF-α SNPs (-308 G > A, -238 G > A) and wild type of -863 CC would be more susceptible to toxic metals.

Replacement of Biphenyl by Bipyridine Enabling Powerful Hole Transport Materials for Efficient Perovskite Solar Cells.

Here, 2,2'- and 3,3'-bipyridine are introduced for the first time as the core structure to get two new hole transport materials (HTMs), namely F22 and F33. The electron-withdrawing nature of bipyridine lowers the HOMO level of the new compounds and enhances the open-circuit voltage of perovskite solar cells. Especially for F33, the better planarity leads to better conjugation in the whole molecule and the molecular interaction is enhanced. Hole-mobility tests, steady-state photoluminescence (PL) spectra as well as time-resolved PL decay results demonstrate that the new HTMs exhibit good hole extraction and hole-transporting property. Impressive power conversion efficiencies of 17.71 and 18.48 % are achieved in conventional planar perovskite (CH3 NH3 PbI3-x Clx ) solar cells containing F22 and F33 as HTMs, respectively. As far as we know, this is the first report on bypiridine-based HTMs with leading efficiencies, and the design motif in this work opens a new way for devising HTMs in the future.

High-Efficiency Perovskite Solar Cells Based on New TPE Compounds as Hole Transport Materials: The Role of 2,7- and 3,6-Substituted Carbazole Derivatives.

In this work, four tetraphenylethylene (TPE)-centered hole transport materials (HTMs), with 2,7- or 3,6-substituted carbazole derivatives as periphery groups are deliberately synthesized and characterized. Their photophysical properties, energy levels, and photovoltaic performances are systematically investigated, and their performances as HTMs are discussed with respect to the different substituent positions on the carbazole moiety. It is interesting to find that the TPE-based HTMs with 2,7-carbazole substituents rival the 3,6-carbazole substituents in hole mobility and hole extraction ability. A high power conversion efficiency of up to 16.74 % is achieved for the devices based on the 2,7-carbazole periphery arms, which is even higher than the one of the "star" HTM Spiro-OMeTAD (2,2-7,7-tetrakis(N,N'-diparamethoxy-phenylamine 9,9'-spirobifluorene) under the same conditions. As far as we know, this is the highest efficiency achieved in tetraphenylethylene derivatives.