Ultra‐Long Crystalline Red Phosphorus Nanowires from Amorphous Red Phosphorus Thin Films

Heating red phosphorus in sealed ampoules in the presence of a Sn/SnI₄ catalyst mixture has provided bulk black phosphorus at much lower pressures than those required for allotropic conversion by anvil cells. Herein we report the growth of ultra‐long 1D red phosphorus nanowires (>1 mm) selectively onto a wafer substrate from red phosphorus powder and a thin film of red phosphorus in the present of a Sn/SnI₄ catalyst. Raman spectra and X‐ray diffraction characterization suggested the formation of crystalline red phosphorus nanowires. FET devices constructed with the red phosphorus nanowires displayed a typical I–V curve similar to that of black phosphorus and a similar mobility reaching 300 cm² V^?1 s with an I_on/I_off ratio approaching 10². A significant response to infrared light was observed from the FET device.     

Red Ionic Water‐Soluble Imidazolium‐Containing Polydiacetylene

Synthesis of a water‐soluble polydiacetylene has been achieved by topochemical polymerization in the solid state of the bis(N‐methylimidazolium)diacetylene monomer. Structural characterization for the monomer by X‐ray diffraction and NMR spectroscopy supports a photopolymerization initiated at the surface. Characterization of the polymer (NMR, UV and Raman spectroscopy, and dynamic light scattering) is given along with a molecular modelling interpretation of the polymerization in the solid state.

     

Far‐Red Organic Fluorophores Contain a Fluorescent Impurity

Far‐red organic fluorophores commonly used in traditional and super‐resolution localization microscopy are found to contain a fluorescent impurity with green excitation and near‐red emission. This near‐red fluorescent impurity can interfere with some multicolor stochastic optical reconstruction microscopy/photoactivated localization microscopy measurements in live cells and produce subtle artifacts in chemically fixed cells. We additionally describe alternatives to avoid artifacts in super‐resolution localization microscopy.     

美丽红色胭脂 魅力红色化学*

介绍了中国胭脂的演变简史,以化学视角对胭脂的发展进行分类:无机胭脂、有机胭脂(天然植物胭脂、有机合成类胭脂)等。进行模拟实验研究,探究胭脂制作工艺流程,分析胭脂中红色物质的成分和显色机制。阐述每个阶段胭脂的不足之处,科普胭脂中的红色化学知识,体会化学对美和健康的重要意义,感受化学的无穷魅力。     

A <Superscript>1</Superscript>H NMR study of Nile Red solvation

In order to evaluate the capabilities of NMR spectroscopy for investigation of the solvatochromic effect in luminophore solutions, the ¹H NMR chemical shifts of Nile Red in mixtures of solvents with different polarities (benzene, toluene, methanol) has been determined. Their dependence upon the solvent mixture composition has been revealed and binding sites for luminophore and solvent component molecules have been determined. The results of the NMR study are consistent with data on the fluorescence of Nile Red solutions in toluene-ethanol mixtures.     

Solvent‐Switching Gelation and Orange–Red Emission of Ultrasmall Copper Nanoclusters

By tuning the Cu???Cu and hydrogen‐bonding interactions, the small cluster Cu₃L can be selectively synthesized to develop a stable and highly fluorescent material, as confirmed by matrix‐assisted laser desorption ionization–time of flight mass spectroscopy. Further characterizations, including absorbance spectroscopy, XPS, and XRD demonstrate the formation of tiny Cu nanoclusters (NCs). In water, the as‐prepared Cu NCs can exhibit high orange fluorescence via solution evaporation to eliminate hydrogen‐bonding, and in dimethylformamide, a strong orange fluorescent gel is obtained by solvent induction to enhance the Cu???Cu and hydrogen‐bonding interactions. More importantly, the Cu NCs in their substantial form exhibit nonlinear optical properties upon two‐photon excitation. These results will shed light on Cu and related cluster applications in two‐photon biological imaging, optical power limiting, and solar energy conversion.     

Rapid magnetic solid‐phase extraction of Congo Red and Basic Red 2 from aqueous solution by ZIF‐8@CoFe2O4 hybrid composites

Core–shell metal–organic framework materials have attracted considerable attention mainly due to their enhanced or new physicochemical properties compared with their single‐component counterparts. In this work, a core–shell heterostructure of CoFe₂O₄‐Zeolitic Imidazolate Framework‐8 (ZIF‐8@CoFe₂O₄) is successfully fabricated and used as an solid‐phase extraction adsorbent to efficiently extract Congo Red and Basic Red 2 dyes from contaminated aqueous solution. Vibrating sample magnetometry indicates that the saturated magnetization of ZIF‐8@CoFe₂O₄ is 3.3 emu/g, which is large enough for magnetic separation. The obtained hybrid magnetic metal‐organic framework based material ZIF‐8@CoFe₂O₄ can remove the investigated dyes very fast within 1 min of the contact time. The adsorbent ZIF‐8@CoFe₂O₄ also shows a good reusability. After regeneration, the adsorbent can still exhibit high removal efficiency (～97%) toward Congo Red for five cycles of desorption–adsorption. This work reveals the great potential of core–shell ZIF‐8@CoFe₂O₄ sorbents for the fast separation and preconcentration of organic pollutants in aqueous solution before high‐performance liquid chromatography analysis.     

Squalene‐Derived Triterpene Polyethers from the Red Alga Laurencia omaezakiana

In our continuing search on halogenated metabolites from species of the red algal genus Laurencia, a novel squalene‐derived triterpene polyether, named omaezakianol ( 2 ), was isolated from Laurencia omaezakiana Masuda along with 15,16‐anhydrothyrsiferol ( 3 ). Their structures were determined by spectral and chemical methods.     

A Far‐Red Emitting Fluorescent Chemogenetic Reporter for In Vivo Molecular Imaging

Far‐red emitting fluorescent labels are highly desirable for spectral multiplexing and deep tissue imaging. Here, we describe the generation of frFAST (far‐red Fluorescence Activating and absorption Shifting Tag), a 14‐kDa monomeric protein that forms a bright far‐red fluorescent assembly with (4‐hydroxy‐3‐methoxy‐phenyl)allylidene rhodanine (HPAR‐3OM). As HPAR‐3OM is essentially non‐fluorescent in solution and in cells, frFAST can be imaged with high contrast in presence of free HPAR‐3OM, which allowed the rapid and efficient imaging of frFAST fusions in live cells, zebrafish embryo/larvae, and chicken embryos. Beyond enabling the genetic encoding of far‐red fluorescence, frFAST allowed the design of a far‐red chemogenetic reporter of protein–protein interactions, demonstrating its great potential for the design of innovative far‐red emitting biosensors.     

Two‐Step Oxidation Synthesis of Sulfur with a Red Aggregation‐Induced Emission

Sulfur is not normally considered a light‐emitting material, even though there have been reports of a dim luminescence of this compound in the blue‐to‐green spectral region. Now, it is shown how to make red‐emissive sulfur by a two‐step oxidation approach using elemental sulfur and Na₂S as starting materials, with a high photoluminescence quantum yield of 7.2 %. Polysulfide is formed first and is partially transformed into Na₂S₂O₃ in the first step, and then turns back to elemental S in the second step. The elevated temperature and relatively oxygen‐deficient environment during the second step transforms Na₂S₂O₃ into Na₂SO₃ incorporated with oxygen vacancies, thus resulting in the formation of a solid‐state powder consisting of elemental S embedded in Na₂SO₃. It shows aggregation‐induced emission properties, attributed to the influence of oxygen vacancies on the emission dynamics of sulfur by providing additional lower energy states that facilitate the radiative relaxation of excitons.     

Cooling,Spectroscopy and Non‐Sticking of trans‐Stilbene and Nile Red

We create and study trans‐Stilbene and Nile Red in a cryogenic (7 K) cell with a low density helium buffer gas. No molecule–helium cluster formation is observed, indicating limited atom–molecule sticking in this system. We place an upper limit of 5 % on the population of clustered He–trans‐Stilbene, consistent with a measured He–molecule collisional residence time of less than 1 μs. With its very low energy torsional modes, trans‐Stilbene is less rigid than any molecule previously buffer‐gas‐cooled into the Kelvin regime. We also report cooling and gas phase visible spectroscopy of Nile Red, a much larger molecule. Our data suggest that buffer gas cooling will be feasible for a variety of small biological molecules.     

Synthesis of a Far‐Red Photoactivatable Silicon‐Containing Rhodamine for Super‐Resolution Microscopy

The rhodamine system is a flexible framework for building small‐molecule fluorescent probes. Changing N‐substitution patterns and replacing the xanthene oxygen with a dimethylsilicon moiety can shift the absorption and fluorescence emission maxima of rhodamine dyes to longer wavelengths. Acylation of the rhodamine nitrogen atoms forces the molecule to adopt a nonfluorescent lactone form, providing a convenient method to make fluorogenic compounds. Herein, we take advantage of all of these structural manipulations and describe a novel photoactivatable fluorophore based on a Si‐containing analogue of Q‐rhodamine. This probe is the first example of a “caged” Si‐rhodamine, exhibits higher photon counts compared to established localization microscopy dyes, and is sufficiently red‐shifted to allow multicolor imaging. The dye is a useful label for super‐resolution imaging and constitutes a new scaffold for far‐red fluorogenic molecules.     

Carbon Dots in a Matrix: Energy‐Transfer‐Enhanced Room‐Temperature Red Phosphorescence

High‐efficiency red room‐temperature phosphorescence (RTP) emissions have been achieved by embedding carbon dots (CDs) in crystalline Mn‐containing open‐framework matrices. The rationale of this strategy relies on two factors: 1) the carbon source, which affects the triplet energy levels of the resulting CDs and thus the spectral overlap and 2) the coordination geometry of the Mn atoms in the crystalline frameworks, which determines the crystal‐field splitting and thus the emission spectra. Embedding the carbon dots into a matrix with 6‐coordinate Mn centers resulted in a strong red RTP with a phosphorescence efficiency of up to 9.6 %, which is higher than that of most reported red RTP materials. The composite material has an ultrahigh optical stability in the presence of strong oxidants, various organic solvents, and strong ultraviolet radiation. A green‐yellow RTP composite was also prepared by using a matrix with 4‐coordinate Mn centers and different carbon precursors.     

Light‐Regulated Polymerization under Near‐Infrared/Far‐Red Irradiation Catalyzed by Bacteriochlorophyll a

Photoregulated polymerizations are typically conducted using high‐energy (UV and blue) light, which may lead to undesired side reactions. Furthermore, as the penetration of visible light is rather limited, the range of applications with such wavelengths is likewise limited. We herein report the first living radical polymerization that can be activated and deactivated by irradiation with near‐infrared (NIR) and far‐red light. Bacteriochlorophyll a (Bachl a) was employed as a photoredox catalyst for photoinduced electron transfer/reversible addition–fragmentation chain transfer (PET‐RAFT) polymerization. Well‐defined polymers were thus synthesized within a few hours under NIR (λ=850 nm) and far‐red (λ=780 nm) irradiation with excellent control over the molecular weight (M_n/M_w<1.25). Taking advantage of the good penetration of NIR light, we showed that the polymerization also proceeded smoothly when a translucent barrier was placed between light source and reaction vessel.     

Dual Illumination Enhances Transformation of an Engineered Green‐to‐Red Photoconvertible Fluorescent Protein

The molecular mechanisms for the photoconversion of fluorescent proteins remain elusive owing to the challenges of monitoring chromophore structural dynamics during the light‐induced processes. We implemented time‐resolved electronic and stimulated Raman spectroscopies to reveal two hidden species of an engineered ancestral GFP‐like protein LEA, involving semi‐trapped protonated and trapped deprotonated chromophores en route to photoconversion in pH 7.9 buffer. A new dual‐illumination approach was examined, using 400 and 505 nm light simultaneously to achieve faster conversion and higher color contrast. Substitution of UV irradiation with visible light benefits bioimaging, while the spectral benchmark of a trapped chromophore with characteristic ring twisting and bridge‐H bending motions enables rational design of functional proteins. With the improved H‐bonding network and structural motions, the photoexcited chromophore could increase the photoswitching‐aided photoconversion while reducing trapped species.