Logic Signal Amplification System for Sensitive Electrochemiluminescence Detection and Subtype Identification of Cancer Cells.

Achieving sensitive detection and accurate identification of cancer cells is vital for diagnosing and treating the disease. Here, we developed a logic signal amplification system using DNA tetrahedron-mediated three-dimensional (3D) DNA nanonetworks for sensitive electrochemiluminescence (ECL) detection and subtype identification of cancer cells. Specially designed hairpins were integrated into DNA tetrahedral nanostructures (DTNs) to perform a catalytic hairpin assembly (CHA) reaction in the presence of target microRNA, forming hyperbranched 3D nanonetworks. Benefiting from the "spatial confinement effect," the DNA tetrahedron-mediated catalytic hairpin assembly (DTCHA) reaction displayed significantly faster kinetics and greater cycle conversion efficiency than traditional CHA. The resulting 3D nanonetworks could load a large amount of Ru(phen)32+, significantly enhancing its ECL signal, and exhibit detection limits for both miR-21 and miR-141 at the femtomolar level. The biosensor based on modular logic gates facilitated the distinction and quantification of cancer cells and normal cells based on miR-21 levels, combined with miR-141 levels, to further identify different subtypes of breast cancer cells. Overall, this study provides potential applications in miRNA-related clinical diagnostics.

Rh(III)-Catalyzed C-H Allylation of Aromatic Ketoximes with Vinylaziridines.

The Rh(III)-catalyzed reaction of aromatic ketoximes with 2-vinylaziridines affords ortho-allylation products of the phenyl rings of aromatic ketoximes in moderate to excellent yields. The reaction requires 0.5 equiv of NaOAc as a base and occurs under mild conditions. The protocol exhibits ortho-monoallylation selectivity, wide scope of substrates, and good compatibility of functional groups.

Pincer Nickel-Catalyzed Olefination of Alcohols with Benzylphosphine Oxides.

N,N,P-Pincer nickel complexes effectively catalyze reaction of alcohols with benzylphosphine oxides to form alkenes in good yields. The protocol suits for a wide scope of substrates and generates only E-configurated alkenes. The method also shows good compatibility of functional groups. Methoxy, methylthio, trifluoromethyl, ketal, fluoro, chloro, bromo, thienyl, and furyl groups are tolerated. The mechanism studies support that the reaction proceeds through catalytic dehydrogenation of alcohols to aldehydes or ketones followed by condensation with benzyldiphenylphosphine oxides in the presence of KOtBu.

Selective identification of p-nitroaniline by bromine-mediated polarization of carbon dots.

A fluorometric method based on boron, bromide-codoped carbon dots (BBCNs) was developed for the first time for the highly selective detection of p-nitroaniline (PNA) in wastewater samples. It should be noted that the introduction of bromine greatly increases the molecular polarizability of the probe, which can regulate the energy level matching between the probe and PNA, resulting in the interaction between BBCNs and PNA. In the presence of PNA, the fluorescence of BBCNs is obviously quenched and accompanied by a red shift of the fluorescence band, which might be attributed to the formation of aggregates caused by the polar adsorption of BBCNs and PNA. It is beneficial for constructing a highly selective sensing platform for PNA determination compared to its isomers (o-nitroaniline and m-nitroaniline) through atomic bromine-mediated polarization of the BBCNs. With the help of this mechanism, an excellent linear range of 0.5-300 µM with a low detection limit of 0.24 µM toward PNA was obtained. This work further confirms that there is a significant relationship between the nature of doping elements and the optical and physicochemical properties of fluorescent materials.

Synthesis of functionalized tetrahydrodibenzo[b,g][1,8]naphthyridin-1(2H)-ones through base-promoted annulation of quinoline-derived dipolarophiles and cyclic enaminones.

An eco-friendly and metal-free method for the synthesis of tetrahydrodibenzo[b,g][1,8]naphthyridin-1(2H)-ones was established. Quinoline-derived dipolarophiles and cyclic enaminones as starting materials undergo a 1,4-Michael addition/SNAr tandem annulation reaction affording the target products. This approach features transition metal-free conditions, good functional group tolerance and operational simplicity.

Ruthenium(II)-Catalyzed S(II)-Directed Aromatic C-H Allylation with Vinylaziridines.

The ruthenium-catalyzed reaction of aryl methyl thioethers with vinylaziridines affords ortho-position mono- or bis-allylation products depending on substituents on the phenyl rings of sulfide substrates or the ratio of reactants. The reaction also features mild reaction conditions, good product yields, wide scope of substrates, good compatibility of functional groups, and the selective formation of E-configurated C-C double bonds.

A single-site porphyrin (Cu)-based COF electrocatalyst for the electrochemical detection of gallic acid sensitively.

Sensitive and convenient determination of gallic acid (GA) is vital for food safety. Here, a novel porphyrin (Cu)-based covalent organic framework named as COF(Cu) was successfully synthesized by condensing pre-metalated 5,10,15,20-tetrakis (para-aminophenyl) porphyrin copper (II) and 2,3,6,7-tetra (4-formylphenyl) tetrathiafulvalene ligands. By combining the advantages of porphyrin with tetrathiafulvalene, it may be possible to create a COF with an intrinsically effective charge-transfer channel. In addition, the Cu-N4 type in the COF(Cu) can be regarded as the single-site electrocatalyst. Benefiting from these advantages, the COF(Cu) based electrochemical sensor demonstrated outstanding response to gallic acid (GA). Under the optimal conditions by square wave voltammetry technique, the COF(Cu) modified electrode showed a wide linear range (0.01-1000 µM), a low detection limit (2.81 nM), good reproducibility, acceptable selectivity as well as high stability. Moreover, the established approach was adopted to detect GA in real tea samples with good recoveries, indicating that the COF(Cu) based electrochemical sensor may pave the way for the application in food analysis.

A Homochiral Fulgide Organic Ferroelectric Crystal with Photoinduced Molecular Orbital Breaking.

Thermally triggered spatial symmetry breaking in traditional ferroelectrics has been extensively studied for manipulation of the ferroelectricity. However, photoinduced molecular orbital breaking, which is promising for optical control of ferroelectric polarization, has been rarely explored. Herein, for the first time, we synthesized a homochiral fulgide organic ferroelectric crystal (E)-(R)-3-methyl-3-cyclohexylidene-4-(diphenylmethylene)dihydro-2,5-furandione (1), which exhibits both ferroelectricity and photoisomerization. Significantly, 1 shows a photoinduced reversible change in its molecular orbitals from the 3 π molecular orbitals in the open-ring isomer to 2 π and 1 σ molecular orbitals in the closed-ring isomer, which enables reversible ferroelectric domain switching by optical manipulation. To our knowledge, this is the first report revealing the manipulation of ferroelectric polarization in homochiral ferroelectric crystal by photoinduced breaking of molecular orbitals. This finding sheds light on the exploration of molecular orbital breaking in ferroelectrics for optical manipulation of ferroelectricity.

Large Phase-Transition Temperature Enhancement Achieved in a Layered Lead Iodide Hybrid Crystal by H/F Substitution.

Organic-inorganic hybrid metal halides with structural flexibility and solution processability have been widely investigated for different application scenarios. However, the effective construction of phase-transition materials with a high phase-transition temperature (Ttr) for potential practical applications remains a great challenge, and reports on the regulation of Ttr with significant enhancement have been rare. In this manuscript, we have realized a large Ttr increase of 148 K in a layered hybrid lead iodide crystal (4-FTMBA)4Pb3I10 (4-FTMBA = 4-fluoro-N,N,N-trimethylbenzenaminium) by the H/F substitution strategy. Compared to the parent (TMBA)4Pb3I10 (TMBA = N,N,N-trimethylbenzenaminium), H/F substitution preserves the structural framework and crystal symmetry in (4-FTMBA)4Pb3I10. The introduction of heavier fluorine will significantly increase the motion barrier for the order-disorder transition, resulting in the remarkably improved Ttr. Temperature-dependent crystal structures, Raman spectra, and dielectric analyses well support the phase-transition behavior. In addition, evident thermochromism with a tunable direct band gap in (4-FTMBA)4Pb3I10 has been observed using UV-vis spectra. To the best of our knowledge, the achieved Ttr enhancement of 148 K by H/F substitution is the highest among the organic-inorganic hybrid lead halide phase-transition materials. This finding would greatly inspire the rational design of functional materials with high performance.

An eco-friendly fluorometric assay for high-sensitive meloxicam quantitation in biological matrices.

Meloxicam (Mel), as a powerful and effective anti-inflammatory drug, is commonly employed for the treatment of various inflammatory diseases; however, the use of Mel at high doses or for extended periods could cause severe side effects in human visceral organs. Therefore, a simple, rapid, and reliable method is urgently needed to monitor Mel in biological samples. Herein, novel water-soluble luminescent nano-carbon dots (nano-Cdots) with outstanding physicochemical properties were prepared by a one-pot high-temperature hydrothermal process of ellagic acid and guanidine. The nano-Cdots were further used as an optical probe for the sensitive detection of Mel in serum samples through the cooperative mechanisms of the inner filter effect and photoelectron transfer. By employing this sensor, an excellent linear correlation was achieved between the relative luminescent intensity [(PL0 - PL)/PL0] and the concentration of Mel in the range of 0.1 to 200 µM, with a limit of detection of 34.68 nM (3σ/k). This sensor was effectively employed for the analysis of Mel in real serum samples, implying its potential development prospects for the advancement of drug analysis with carbon-based probes.

The First Enantiomeric Stereogenic Sulfur-Chiral Organic Ferroelectric Crystals.

Chiral ferroelectric crystals with intriguing features have attracted great interest and many with point or axial chirality based on the stereocarbon have been successively developed in recent years. However, ferroelectric crystals with stereogenic heteroatomic chirality have never been documented so far. Here, we discover and report a pair of enantiomeric stereogenic sulfur-chiral single-component organic ferroelectric crystals, Rs -tert-butanesulfinamide (Rs -tBuSA) and Ss -tert-butanesulfinamide (Ss -tBuSA) through the deep understanding of the chemical design of molecular ferroelectric crystals. Both enantiomers adopt chiral-polar point group 2 (C2 ) and exhibit mirror-image relationships. They undergo high-temperature 432F2-type plastic ferroelectric phase transition around 348 K. The ferroelectricity has been well confirmed by ferroelectric hysteresis loops and domains. Polarized light microscopy records the evolution of the ferroelastic domains, according with the fact that the 432F2-type phase transition is both ferroelectric and ferroelastic. The very soft characteristics with low elastic modulus and hardness reveals their excellent mechanical flexibility. This finding indicates the first stereosulfur chiral molecular ferroelectric crystals, opening up new fertile ground for exploring molecular ferroelectric crystals with great application prospects.

Photochromic Single-Component Organic Fulgide Ferroelectric with Photo-Triggered Polarization Response.

Organic photochromic compounds have been widely investigated for optical memory storage and switches. Very recently, we pioneeringly discovered optical control of ferroelectric polarization switching in organic photochromic salicylaldehyde Schiff base and diarylethene derivatives, differently from the traditional ferroelectrics. However, the study of such intriguing photo-triggered ferroelectrics is still in its infancy and relatively scarce. In this manuscript, we synthesized a pair of new organic single-component fulgide isomers, (E and Z)-3-(1-(4-(tert-butyl)phenyl)ethylidene)-4-(propan-2-ylidene)dihydrofuran-2,5-dione (1E and 1Z). They undergo prominent photochromism from yellow to red. Interestingly, only polar 1E has been proven to be ferroelectric, while the centrosymmetric 1Z does not meet the basic requirement for ferroelectricity. Besides, experimental evidence shows that the Z-form can be converted to the E-form by light irradiation. More importantly, the ferroelectric domains of 1E can be manipulated by light in the absence of an electric field, benefiting from the remarkable photoisomerization. 1E also adopts good fatigue resistance to the photocyclization reaction. As far as we know, this is the first example of organic fulgide ferroelectric reported with photo-triggered ferroelectric polarization response. This work has developed a new system for studying photo-triggered ferroelectrics and would also provide an expected perspective on developing ferroelectrics for optical applications in trap future.

Nickel-catalyzed reductive coupling of arylcarboxylic acid 2-pyridyl esters with alkyl methanesulfonates: access to alkyl aryl ketones.

Alkyl aryl ketones were synthesized via a nickel-catalyzed reductive coupling reaction of arylcarboxylic acid (2-pyridyl)esters with primary and secondary alkyl methanesulfonates under mild reaction conditions. This method suits a wide range of substrates and shows good compatibility with functional groups.

Large Piezoelectric Response in a Metal-Free Three-Dimensional Perovskite Ferroelectric.

Metal-free perovskites with light weight and eco-friendly processability have received great interest in recent years due to their superior physical features in ferroelectrics, X-ray detection, and optoelectronics. The famous metal-free perovskite ferroelectric MDABCO-NH4-I3 (MDABCO = N-methyl-N'-diazabicyclo[2.2.2]octonium) has been demonstrated to exhibit excellent ferroelectricity comparable to that of inorganic ceramic ferroelectric BaTiO3, such as large spontaneous polarization and high Curie temperature (Ye et al. Science 2018, 361, 151). However, piezoelectricity as a vitally important index is far from enough in the metal-free perovskite family. Here, we report the discovery of large piezoelectric response in a new metal-free three-dimensional perovskite ferroelectric NDABCO-NH4-Br3 (NDABCO = N-amino-N'-diazabicyclo[2.2.2]octonium) by replacing the methyl group of MDABCO with the amino group. Besides the evident ferroelectricity, strikingly, NDABCO-NH4-Br3 shows a large d33 of 63 pC/N more than 4 times that of MDABCO-NH4-I3 (14 pC/N). The d33 value is also strongly supported by the computational study. To the best of our knowledge, such a large d33 value ranks the highest among the documented organic ferroelectric crystals to date and represents a major breakthrough in metal-free perovskite ferroelectrics. Combined with decent mechanical properties, NDABCO-NH4-Br3 is expected to be a competitive candidate for medical, biomechanical, wearable, and body-compatible ferroelectric devices.

Boron-enriched rice-like homologous carbon nanoclusters with a 51.5% photoluminescent quantum yield for highly sensitive determination of endogenous hydroxyl radicals in living cells.

Exploring the ultrahigh quantum efficiency of a carbon-based probe via a green and simple technique, and utilisation of its sensing ability for highly bioactive molecule detection is still highly challenging. Herein, we prepared a novel boron-enriched rice-like homologous carbon nanoclusters (BRCNs) with an ultrahigh quantum efficiency of ∼51.5% by introduction of a conjugated structure attached to the CN bond and an electron-withdrawing boron active centre. Unexpectedly, the BRCNs obtained showed a stable dispersion of rice-like carbon nanograins, composed of small carbon dot assembled nanoclusters with an average diameter size of ∼30 nm, and containing boron units of ∼24.68 at%. What's exciting is that the BRCNs obtained exhibited an "on-off-on" three-state emission with the addition of an hydroxyl radical (OH˙) and its antioxidants. Thus, two distinctive fluorescent responses for OH˙ and antioxidants based on the BRCN probe had been developed, and the mechanism has been determined using TEM, XPS, FT-IR, FL, UV-vis spectrophotometry, UPS and fluorescent lifetimes. The OH˙, generated from the Fenton's reagent, preferentially attack the electron-deficient vacancy p orbit of the boron atom in the surface of the BRCNs, which results in the boron atom being easily substituted/attacked by OH˙, and leading to spontaneous aggregation induced quenching (AIQ) due to the existence of a strong intermolecular hydrogen bond between denatured BRCNs. Furthermore, the proposed method was also successfully applied to monitor endogenous OH˙ generation in HeLa cells by confocal imaging, which could be used for elucidating OH˙-induced oxidative damage to biological tissues and proteins.

Copper-Catalyzed Reaction of 2,3-Allenols with Silylzinc Reagents: Access to 2-Silyl-1,3-butadienes.

Reaction of 2,3-allenols with PhMe2SiZnCl or Ph2MeSiZnCl under catalysis of IPrCuCl or SIPrCuCl was carried out, affording 2-silyl-1,3-butadienes. Secondary and tertiary 2,3-allenols could be used as coupling partners. Reaction of secondary 2,3-allenols gave (E)-2-silyl-1,3-butadienes as the only products.

Rhodium(I)-Catalyzed P(III)-Directed Aromatic C-H Acylation with Amides.

The rhodium-catalyzed P(III)-directed aromatic C-H acylation reaction with amides is described. The reaction features a simple catalyst system, mild reaction conditions, monoacylation selectivity, a wide scope of substrates, and good compatibility of functional groups.

One-pot green preparation of deep-ultraviolet and dual-emission carbon nanodots for dual-channel ratiometric determination of polyphenol in tea sample.

A novel deep-ultraviolet and dual-emission carbon nanodots (DUCDs)-based dual-channel ratiometric probe was prepared by a one-pot environmental-friendly hydrothermal process using guanidine as the only starting material for sensing polyphenol in tea sample (TPPs). Under the exposure to TPPs, the DUCDs not only provided a characteristic colorimetric response to TPPs, but also displayed TPPs-sensitive ratiometric fluorescence quenching. The detection mechanism was proved to be that enrichment-specific hydroxyl sites (e.g., -NH2 and -COOH) of DUCDs can specifically react with phenolic hydroxyl groups of TPPs to generate dynamic amide and carboxylate bonds by dehydration and/or condensation reaction. As a result, a new carbon nanomaterial with decrement of surface passivation groups, inherent light-absorbing, and invalid fluorescence emission was generated. The ratio (FL297nm/FL395nm) of fluorescence intensity at 297 nm and 395 nm of DUCDs excited at 275 nm decreased with increasing TPPs concentration. The linearity range was 5.0 ng/mL to 100 µg/mL with a detection limit (DL) of 3.5 ± 0.04 ng/mL for TPPs (n = 3, 3σ/k). Colorimetry of DUCDs, best measured as absorbance at 320 nm, was increased linearly in the TPP concentration range 200 ng/mL-200 µg/mL with a DL of 94.7 ± 0.04 ng/mL (n = 3, 3σ/k). The probe was successfully applied to the determination of TPPs in real tea samples, showing potential application prospects in food analysis.

Domain memory effect in the organic ferroics.

Shape memory alloys have been used extensively in actuators, couplings, medical guide wires, and smart devices, because of their unique shape memory effect and superelasticity triggered by the reversible martensitic phase transformations. For ferroic materials, however, almost no memory effects have been found for their ferroic domains after reversible phase transformations. Here, we present a pair of single-component organic enantiomorphic ferroelectric/ferroelastic crystals, (R)- and (S)-N-3,5-di-tert-butylsalicylidene-1-(1-naphthyl)ethylamine SA-NPh-(R) and SA-NPh-(S). It is notable that not only can their ferroic domain patterns disappear and reappear during reversible thermodynamic phase transformations, but they can also disappear and reappear during reversible light-driven phase transformations induced by enol-keto photoisomerization, both of which are from P1 to P21 polar space groups. Most importantly, the domain patterns are exactly the same in the initial and final states, demonstrating the existence of a memory effect for the ferroic domains in SA-NPh-(R) and SA-NPh-(S). As far as we are aware, the domain memory effect triggered by both thermodynamic and light-driven ferroelectric/ferroelastic phase transformations remains unexplored in ferroic materials. Thermal and optical control of domain memory effect would open up a fresh research field for smart ferroic materials.

Giant electromechanical effects in polymers.

A four-ingredient polymer chain has record-breaking piezoelectric capability.