A family of functional Ln‐organic framework constructed by iodine‐substituted aromatic polycarboxylic acid for turn‐off sensing of UO22+

With the rapid development of nuclear energy, one of the main constraints restricting the development of nuclear energy is the long‐term safe disposal of strong uranium waste. Here it is a great significance that we use four new synthetic Ln (III)‐based coordination polymers to test the uranium solution. In this study, four three‐dimensional coordination polymers 1 – 4 (CPs‐( 1–4 ); Ln = Eu, Gd, Sm, Nd) were successfully synthesized through 1:1 complexation of Ln (NO₃)₃·6H₂O with poly‐carboxylic acid ligand H₃TIBTC (2,4,6‐Triiodo‐1,3,5‐benzene tricarboxylic acid) which contains substituents of the carboxylic acid group and halogen atom, respectively. Based on the ligand being excellent fluorescent properties in the solution, it prompted us to further study the fluorescence properties of the coordination polymers. Experimental results show that the coordination polymers are favorable materials for the simultaneous selective detection uranium solution from water, being potentially useful in monitoring water quality and treating uranium‐wastewater.     

Synthesis of ethynylpyrene-modified 3-deaza-2′-deoxyguanosines as environmentally sensitive fluorescent nucleosides: Target DNA-sequence detection via changes in the fluorescence wavelength

Novel pyrene-labeled environmentally sensitive fluorescent (ESF) nucleosides [^1p3zG (1a) and ^2p3zG (1b)] possessing the 3-deazaguanine skeleton were synthesized. Among them, ^1p3zG (1a) exhibited longer fluorescence emission wavelengths compared with the previously reported naphthalene-modified ESF nucleoside ^3nzG (48–71?nm longer in polar solvents) and showed remarkable solvent-polarity-sensitive fluorescence properties. Oligodeoxynucleotide (ODN) probes containing ^1p3zG (1a) clearly discriminated target DNAs by the change in the emission wavelength and intensity through monitoring the microenvironmental change around the DNA minor groove. Thus, these pyrene-labeled ESF nucleosides can be applied in gene detection and molecular diagnostics, as well as in the structural analysis of nucleic acids.     

Solid-Phase Synthesis of Fluorescent Probes for Plasma Membrane Labelling

The cellular plasma membrane plays a fundamental role in biological processes, including cell growth, signaling and transport. The labelling of the plasma membrane with targeted fluorescent probes offers a convenient and non-invasive way to image the morphological changes and dynamics of a membrane in real-time and, despite many examples of fluorescent plasma membrane probes, a “universal targeting/anchoring moiety” is still required. In this study, a small number of stearic acid-based probes labelled with 6-carboxyfluorescein was designed and fabricated via solid-phase synthesis in which variations in both charge and hydrophobicity were explored. To ease the synthesis process, a gram-scale synthesis of the Fmoc-Lys(6-carboxyfluoresein diacetate)-OH building block was developed, allowing the discovery of optimal probes that carried a positively charged amino group and a stearic acid tail that exhibited intense plasma membrane brightness and robust retention.     

Persistent Homology to Quantify the Quality of Surface-Supported Covalent Networks

Covalent networks formed by on-surface synthesis usually suffer from the presence of a large number of defects. We report on a methodology to characterize such two-dimensional networks from their experimental images obtained by scanning probe microscopy. The computation is based on a persistent homology approach and provides a quantitative score indicative of the network homogeneity. We compare our scoring method with results previously obtained using minimal spanning tree analyses and we apply it to some molecular systems appearing in the existing literature.     

Fast-response fluorescent probe with favorable water solubility for highly sensitive imaging of endogenous tyrosinase in living cells and zebrafish model

Tyrosinase (TYR) is an important polyphenolic oxidase enzyme and usually regards as a biomarker of melanoma cancer. Highly effective tracking TYR activity in vivo will help to study the mechanism of TYR in living organisms and forecasts related diseases. In this study, we present a novel TYR-activatable fluorescent probe (CHMC-DOPA) for tracking TYR activity in vitro and in vivo. CHMC-DOPA is constructed by incorporating dopamine (DOPA) moiety into a fluorescent chloro-hydroxyl-merocyanine (CHMC) scaffold. Upon exposure to TYR, the dopamine unit in CHMC-DOPA is oxidized to a dopaquinone derivative, and an intramolecular photo-induced electron transfer (PET) process between CHMC fluorophore and o-dopaquinone will take place, the fluorescence of CHMC-DOPA is quenched rapidly. Therefore, the evaluation of TYR activity is established in terms of the relationship between fluorescence quenching efficiency and TYR activity. In our experiments, CHMC-DOPA shows various advantages, such as fast response (8?min), low concentration of TYR activation (0.5 U/mL), good water-solubility, as well as the lowest detection limit (0.003 U/mL) compared with previously reported works. Furthermore, CHMC-DOPA also exhibits excellent cell membrane permeability and low cytotoxicity, which is successfully used to monitor endogenous TYR activity in living cancer cells and zebrafish models. CHMC-DOPA performs well, and we anticipate that this newly designed novel platform will provide an alternative for high effective monitoring TYR activity in biosystems.     

Novel Lipophilic Fluorophores with Highly Acidity-Dependent Two-Photon Response

Lipophilic fluorophores are widely implemented in nonlinear microscopy; however, few existing membrane-specific probes combine the high brightness of two-photon excited fluorescence (2PEF) with pH sensitivity. Herein we describe four novel two-photon excited fluorophores, based on a coumarin 151 core structure, where lipophilicity is induced by a covalently attached phosphazene moiety. Changing the environmental acidity using trifluoromethanesulfonic (triflic) acid leads to profound changes in the linear fluorescence and 2PEF characteristics, due to chromophores’ switching between neutral- and protonated forms. We characterize this dependence by measuring the two-photon absorption (2PA) spectra over the region λ_2PA=550–1000 nm, observing 2PA cross sections of σ_2PA=10–20 GM, with an associated 2PEF brightness of 10–13 GM, in neutral solutions of both acetonitrile and n-octanol. Although quantum chemical modelling and NMR measurements show that, at high chromophore concentrations, protonation may be accompanied by a dimerization process, these dimers likely do not form at the lower concentrations used in optical spectroscopy.     

Bulk Mn2+ Doped 1D Hybrid Lead Halide Perovskite with Highly Efficient,Tunable and Stable Broadband Light Emissions

Mn²⁺ doped colloidal three-dimensional (3D) lead halide perovskite nanocrystal (PNC) has attracted intensive research attention; however, the low exciton binding energy and fatal optical instability of 3D PNC seriously hinder the optoelectronic application. Therefore, it remains significant to explore new stable host perovskite with strongly bound exciton to realize more desirable luminescent property. In this work, we utilized bulk one-dimensional (1D) hybrid perovskite of [AEP]PbBr₅ ⋅ H₂O (AEP=N-aminoethylpiperazine) as structural platform to rationally optimize the luminescent property by a controllable Mn²⁺ doping strategy. Significantly, the series of Mn²⁺-doped 1D [AEP]PbBr₅ ⋅ H₂O show enhanced energy transfer efficiency from the strongly bound excitons of host material to 3d electrons of Mn²⁺ ions, resulting in tunable broadband light emissions from weak yellow to strong red spectral range with highest photoluminescence quantum yield up to 28.41 %. More importantly, these Mn²⁺-doped 1D perovskites display ultrahigh structural and optical stabilities in humid atmosphere, water and high temperature exceeding the conventional 3D PNC. Combined highly efficient, tunable and stable broadband light emissions enable Mn²⁺-doped 1D perovskite as excellent down-converting phosphor showcasing the potential application in white light emitting diode. This work not only provides a profound understanding of low-dimensional perovskites but also opens a new way to rationally design high-performance broadband light emitting perovskites for solid-state lighting and displaying devices.     

Interfacially Super-Assembled Benzimidazole Derivative-Based Mesoporous Silica Nanoprobe for Sensitive Copper (II) Detection and Biosensing in Living Cells

Mesoporous silica nanoparticles (MSNs) functionalized with benzimidazole-derived fluorescent molecules (DHBM) are fabricated via a feasible interfacial superassembly strategy for the highly sensitive and selective detection of Cu²⁺. DHBM-MSN exhibits an obvious quenching effect on Cu²⁺ in aqueous solutions, and the detection limit can be as low as 7.69×10⁻⁸ M. The DHBM-MSN solid-state sensor has good recyclability, and the silica framework can simultaneously improve the photostability of DHBM. Two mesoporous silica nanoparticles with different morphologies were specially designed to verify that nanocarriers with different morphologies do not affect the specific detectionability. The detection mechanism of the fluorescent probe was systematically elucidated by combining experimental results and density function theory calculations. Moreover, the detection system was successfully applied to detect Cu²⁺ in bovine serum, juice, and live cells. These results indicate that the DHBM-MSN fluorescent sensor holds great potential in practical and biomedical applications.     

Indole-Based Long-Wavelength Fluorescent Probes for Bioimaging of S-Nitrosylation in Mitochondria

S-Nitrosylation has been found to play an important role in regulating mitochondrial function. However, probes for detection of protein S-nitrosylation in mitochondria remain unexplored. Herein, a novel 4-(pyridin-4-yl)vinyl-substituted indole was designed, exhibiting a long-wavelength emission and a high fluorescent quantum yield. Functionalization of the 7-position of the indole ring with an arylphosphine ester resulted with probes with efficient mitochondria-targeting ability. Furthermore, the indole-arylphosphine displayed a significant fluorescence enhancement upon exposure to S-nitrosoglutathione (GSNO) at low micromolar concentrations in A431 cells. Taken together, this study provides a new indole-based fluorescent probe with a unique long-wavelength emission for direct detection of S-nitrosylation in mitochondria, which may represent a powerful tool for understanding the critical roles of S-nitrosylation within mitochondria of living organisms.     

Overcoming Steric Hindrance in Aryl-Aryl Homocoupling via On-Surface Copolymerization

On-surface synthesis is a unique tool for growing low-dimensional carbon nanomaterials with precise structural control down to the atomic level. This novel approach relies on carefully designed precursor molecules, which are deposited on suitable substrates and activated to ultimately form the desired nanostructures. One of the most applied reactions to covalently interlink molecular precursors is dehalogenative aryl-aryl coupling. Despite the versatility of this approach, many unsuccessful attempts are also known, most of them associated to the poor capability of the activated precursors to couple to each other. Such failure is often related to the steric hindrance between reactants, which may arise due to their coplanarity upon adsorption on a surface. Here, we propose a copolymerization approach to overcome the limitations that prevent intermolecular homocoupling. We apply the strategy of using suitable linkers as additional reactants to the formation of fully conjugated polycyclic nanowires incorporating non-benzenoid rings.