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The synthesis of cyclic carbonates through cycloaddition reactions between epoxides and carbon dioxide (CO2) is an important industrial process. Metal-Organic Frameworks (MOFs) have functional and ordered pore structures, making them attractive catalysts for converting gas molecules into valuable products. One approach to enhance the catalytic activity of MOFs in CO2 cycloaddition reactions is to create open metal sites within MOFs. In this study, the amino-functionalized rare earth Gd-MOF (Gd-TPTC-NH2) and its ionic liquid composite catalysts (Gd-TPTC-NH-[BMIM]Br) were synthesized using 2'-amino-[1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid (H4TPTC-NH2) as the ligand. The catalytic performance of these two catalysts was observed in the cycloaddition reaction of CO2 and epoxides. Under the optimized reaction conditions, Gd-TPTC-NH-[BMIM]Br can effectively catalyze the cycloaddition reaction of a variety of epoxide substrates with good to excellent yields of cyclic carbonate products. Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, promote higher yields of cyclic carbonates due to the electron-withdrawing nature of Cl and Br substituents. Additionally, the Gd-TPTC-NH- [BMIM]Br catalyst demonstrated good recyclability and reproducibility, maintaining its catalytic activity without any changes in its structure or properties after five reuse cycles. [ABSTRACT FROM AUTHOR]

A series of highly reduced Mo red clusters {Mo28} (1), {Mo30} (2), and {Mo40} (3) are synthesized from the rational assembly of planar {MoV4} building blocks and employed for proton conduction. 3 exhibits the best conductivity of 7.56 × 10-3 S cm-1 under optimal conditions due to the most efficient hydrogen-bonding network. [ABSTRACT FROM AUTHOR]

Incorporating catalytic units into a crystalline porous matrix represents a facile way to build high-efficiency heterogeneous catalysts, and by rational design of the porous skeleton with appropriate building blocks the catalytic performance can be significantly enhanced for a series of organic transformations owing to the synergistic effect from the multicomponent and confined porous microenvironment around catalytically active sites. Herein, we demonstrate that the design and synthesis of a porous polyoxometalate-based metal–organic framework YL2(H2O)2[CrMo6O18(PET)2]·4H2O (POMOF-1) constructed from Anderson-type [CrMo6O18(PET)2] (PET = pentaerythritol), which can be employed as a multifunctional platform for synthesis of N-containing compounds via selective oxidative coupling with amines. POMOF-1 features microporous 1D channels defined by Y3+ and L, with [CrMo6O18(PET)2] arranged orderly between adjacent Lvia electrostatic interactions. Upon using POMOF-1 as a catalyst and H2O2 as an oxidant, a variety of amines could be effectively converted to value-added amides, imines and azobenzenes via the oxidative cross-coupling with alcohols or homo-coupling. In particular, POMOF-1 showed dramatically improved activity for the N-formylation reaction owing to the synergistic and confinement effect, with the yield of amides up to 95% and 4 times higher than that of homogeneous [CrMo6O18(PET)2]. Meanwhile, the oxidative homo-coupling of arylmethylamines and arylamines can be facilely tuned by adjustment of the amount of oxidant, solvent and additive, affording imines and azobenzenes in high selectivity and yield, respectively. POMOF-1 is robust and can be reused for 5 cycles with little loss of catalytic activity and structural integrity. The work demonstrates that the combination of catalytically active POMs with crystalline porous MOFs holds great potential to build robust and recyclable heterogeneous systems with enhanced activity and selectivity for multifunctional catalysis. [ABSTRACT FROM AUTHOR]

Push–pull π-conjugated molecules are one of the paradigms of second order nonlinear optical (NLO) materials and have been extensively explored. However, high-performance second order NLO materials with an optimum electron donor (D), π-bridge (π) and acceptor (A) under this paradigm are still the most sought-after. In the present work, D–π–A molecules with optimal D, π and A combination for strong second order NLO properties are proposed based on molecular orbital theories. The optimal D–π–A push–pull molecule achieves an unprecedentedly strong NLO response under the D–π–A paradigm, i.e., the static first hyperpolarizability reaches −453.92 × 10−30 esu per heavy atom using azulene as part of the π-bridge and acceptor to synergistically reinforce the strength of the acceptor. The protocols of D–π–A NLO molecule design through frontier molecular orbital matching of D, π and A with optimal combination of electron donating and accepting strengths shed light on future molecular NLO materials exploration. The simulated two-dimensional second order spectra provide useful information (e.g., sum frequency generation) on the applications of those D–π–A push–pull molecules in nonlinear optics. [ABSTRACT FROM AUTHOR]

We report the first visible light photocatalytic oxidation of NO on CdS nanorods (CdS-NRs), one of the typical reduction type semiconductor photocatalysts. The NO removal rate in a continuous reactor sharply increases from 44% to 58% after in situ deposition of Bi nanoplates on CdS-NRs. The LSPR effect of metallic Bi causes the dramatic production of superoxide radicals (˙O2−) and singlet oxygen (1O2) that are responsible for the oxidation of NO. [ABSTRACT FROM AUTHOR]

The modulation of selectivity of transfer hydrogenation of alkynes to E-alkenes using formic acid is a challenge due to the limited knowledge of the complex reaction network, including oxidative addition, decarboxylation, reductive elimination, Z→E isomerization, and β-H elimination. Here, the search for the reaction pathway and experiment explorations revealed that the selectivity of Pd(PMe3)4-catalyzed hydrogenation of 1-phenyl-1-propyne to (E)-1-phenylpropene is controlled by the water content in the aqueous solution of formic acid and the reaction time. The combination of an automatic reaction pathway search and density functional theory (DFT) calculations found that the intermolecular hydrogen bonds with water molecules have an influence on lowering the free energy activation barrier of transition states in the oxidative addition steps. The reasonable reaction barriers of Z→E isomerization and hydrogenation result in the dependence of selectivity on reaction time, which has been supported by experiments. By using molecular sieves, the water in formic acid is removed, and the yield of the desired (Z)-1-phenylpropene product increases to the highest value (86%) in 5 hours but decreases to 54% when the reaction is run for 16 hours due to the further Z→E isomerization and hydrogenation. In the second stage which starts from (Z)-1-phenylpropene, the yield of (E)-1-phenylpropene decreased from 90% (with 4 Å MS) to 67% in the aqueous solution of formic acid. [ABSTRACT FROM AUTHOR]

The interaction between monolayered arsenene and fourteen kinds of solvents is found to be correlated with the extent of charge transfer from arsenene to the solvents by density functional theory calculations. Among them, three kinds of aprotic solvents (cyclohexane, tetrahydrofuran and chloroform), representing different adsorbability with arsenene, were selected to exfoliate bulk arsenic crystals into nanosheets in experiments. The as-prepared concentrations of the three dispersions vary monotonically with the calculated adsorption energies and charge transfer per contact area. Transmission electron microscopy (TEM) characterization and size distribution analyses manifested that the lateral size distributions of the exfoliated arsenic nanosheets ranged from 100 nm to 1050 nm. This strategy shows the potential usage in liquid-phase exfoliation of multi-layered materials due to the interaction effects between the solvents and the surface of the materials. [ABSTRACT FROM AUTHOR]

A conjugated BODIPY–triphenylamine multi-aldoxime (BTN) was designed and synthesized by the Sonogashira coupling reaction. The chemodosimeter showed a red emission (670 nm), fast response (within seconds), high selectivity and good sensitivity towards hypochlorite based on the redox reaction of four aldoximes. BTN possessed two original absorption peaks at 366 nm and 588 nm, respectively, corresponding to fluorescence emissions at 440 nm and 660 nm, which exhibited a ratiometric change in the presence of hypochlorite. With the addition of hypochlorite, the redox reaction of aldoxime led to the termination of isomerization of the C=N bond, the fluorescence intensity at 660 nm gradually changed from weak to strong, accompanied by a slight 10 nm red-shift; in contrast, the fluorescence intensity began to decrease at 440 nm. Moreover, as the two-photon excited fluorescent NaOCl probe, BTN afforded an enhanced signal response for hypochlorite at 686 nm under two-photon excitation (λTPEFex = 800 nm). Meanwhile, successful imaging of living cells was carried out for BTN towards hypochlorite in A-549 cells. The results demonstrated that BTN had potential application prospects and was promising for practical application in biological systems and environmental systems. [ABSTRACT FROM AUTHOR]

The joint computational and experimental efforts reveal that the organic molecule 1,2-diisocyano-4,5-dimethylbenzene (1) acts as both a reactant and a photosensitizer (PS) in a metal-free reaction with perfluoroalkylhalide (2) to produce 2-perfluoroalkyl quinoxalines (3) under visible light. Both the π–π stacking aggregation in crystals and the solvation in various solvents of PS 1 exhibited visible-light absorption at 466 nm in spite of its smaller coefficient than that of the ultraviolet-light absorption. Such an aggregation-assisted visible-light absorption phenomenon is rationalized by theoretical calculations of the condensed-phase properties with the consideration of the explicit polarization effect from the neighboring molecules. Upon irradiation with different wavelengths, the emission colors changed from navy to bright yellow. Fluorescence lifetime measurements show that the emission of 1 comes from its singlet excited state. The aggregation induced emission when excited at 420 nm has a shorter lifetime (0.45 ns) than that of the emission from isolated molecules (2.71 ns) when excited at 381 nm. It is conceived that the aggregation assisted visible light absorption properties may be general in other photo-reactive molecules, such as 1,4-diisocyano-2,5-dimethylbenzene (4), 1,4-dicyanobenzene (5), and 1,4-diisocyanobenzene (6), which are widely used in many photochemical reactions in the absence of any external photosensitizer. [ABSTRACT FROM AUTHOR]

A smart two-photon fluorescent platform based on desulfurization–cyclization was developed by attaching rhodamine to a cyanine skeleton through the Knoevenagel reaction. Based on the platform, a CyRSN probe was rationally designed and synthesized, in which morpholinyl naphthalimide and modified rhodamine thiohydrazide were linked to form a structure of monothio-bishydrazide. The probe exhibits excellent two-photon properties toward Hg2+ under Ti:sapphire pulsed laser 800 nm irradiation, allowing the naked-eye signal and fluorescence “turn-on” signal at 746 nm to be obviously distinguished. The addition of Hg2+ to the probe ensured that the naphthalimide donor and modified rhodamine acceptor were connected with electronically conjugated bonds (1,2,4-oxadiazole). Hence, a typical TBET process took place, resulting in an increase of the modified rhodamine NIR emission at 746 nm by about 34-fold as well as a decrease of the naphthalimide emission at 540 nm and producing a colorimetric change from pale yellow to green. The chemodosimeter exhibits a stable response for Hg2+ over other metal ions with a detection limit of 1.91 × 10−7 M, high sensitivity, a rapid response time, and pH independence under neutral conditions (pH 6.0–10.0). In addition, the CyRSN probe was successfully applied in the detection and quantification of Hg2+ in water samples with satisfactory recovery results. [ABSTRACT FROM AUTHOR]

Hypochlorite serves as a significant antimicrobial agent in the human immune system, and its detection is of great importance. Herein, a novel near-infrared BODIPY-based ClO− fluorescent probe (NCS-BOD-OCH3) was designed and synthesized. The emission bands of NCS-BOD-OCH3 concentrated at 595 nm and 665 nm. Since the electron withdrawing group 1,3,4-oxadiazole was formed after the desulfurization reaction, the fluorescence intensity of NCS-BOD-OCH3 decreased significantly in THF/H2O (v/v, 1 : 1, buffered with 10 mM PBS pH = 7.4), which is visible to the naked eye with an obvious color change. NCS-BOD-OCH3 can realize the two-photon up-converted fluorescence emission. The low detection limit was calculated from the titration results, with the figure for NCS-BOD-OCH3/ClO− being 1.15 × 10−6 M. The result of living cell imaging experiment demonstrated that NCS-BOD-OCH3 can successfully detect ClO− in living cells and can serve as a NIR mitochondrial imaging agent. It is an excellent platform for developing NIR ClO− fluorescent probes. [ABSTRACT FROM AUTHOR]

Luminescent materials with aggregation-induced emission (AIE) properties have attracted considerable interest for their promising applications in light-emitting and display devices and fluorescent chemosensors. Coumarin and its derivatives are one of the most attractive chromophores due to their excellent properties, such as high fluorescence quantum yield, large Stokes shift, less toxicity, ease of modification and visible wavelength emission. A coumarin-based AIE-active red fluorogen was designed and synthesised. It was found that CDPA exhibits AIE property, red emission, self-assembly and thermally activated delayed fluorescence (TADF) in the solid state. [ABSTRACT FROM AUTHOR]

Copper (Cu) is one of the essential microelements for plants and algae. It can stimulate growth and photosynthesis at low concentration but inhibit them at higher concentration. The knowledge of molecular response mechanisms to copper stress in green algae is still limited. The responses of the green algae Dunaliella salina to Cu stress were studied using the physiochemical indexes and RNA-seq analysis. The physiochemical indexes such as growth rate, the content of chlorophyll and soluble sugar, photosynthesis and peroxidase activity were all changed in D. salina under Cu stress. In addition, a total of 3799 differentially expressed genes (DEGs) were identified between the control and Cu-treated group. Among these, 2350 unigenes were up-regulated whereas 1449 were down-regulated. Here, the DEGs encoding proteins relevant to photosynthesis, carbon assimilation and carbohydrate mechanism were significantly up-regulated in the Cu-treated group. In addition, the unigenes encoding proteins involved in the antioxidant system and heat shock proteins were also up-regulated, and these were consistent with the expression patterns based on TPM (transcripts per million) values. This study shows that the enhanced growth and photosynthesis and carbon mechanism in D. salina can be triggered by copper, which will lay a firm foundation for future breeding and carotenoid production, further highlighting the underlying application of D. salina as a functional food.

The modulation of selectivity of transfer hydrogenation of alkynes to E-alkenes using formic acid is a challenge due to the limited knowledge of the complex reaction network, including oxidative addition, decarboxylation, reductive elimination, Z→E isomerization, and β-H elimination. Here, the search for the reaction pathway and experiment explorations revealed that the selectivity of Pd(PMe 3 ) 4 -catalyzed hydrogenation of 1-phenyl-1-propyne to (E)-1-phenylpropene is controlled by the water content in the aqueous solution of formic acid and the reaction time. The combination of an automatic reaction pathway search and density functional theory (DFT) calculations found that the intermolecular hydrogen bonds with water molecules have an influence on lowering the free energy activation barrier of transition states in the oxidative addition steps. The reasonable reaction barriers of Z→E isomerization and hydrogenation result in the dependence of selectivity on reaction time, which has been supported by experiments. By using molecular sieves, the water in formic acid is removed, and the yield of the desired (Z)-1-phenylpropene product increases to the highest value (86%) in 5 hours but decreases to 54% when the reaction is run for 16 hours due to the further Z→E isomerization and hydrogenation. In the second stage which starts from (Z)-1-phenylpropene, the yield of (E)-1-phenylpropene decreased from 90% (with 4 Å MS) to 67% in the aqueous solution of formic acid.

Hypochlorite serves as a significant antimicrobial agent in the human immune system, and its detection is of great importance. Herein, a novel near-infrared BODIPY-based ClO - fluorescent probe (NCS-BOD-OCH 3 ) was designed and synthesized. The emission bands of NCS-BOD-OCH 3 concentrated at 595 nm and 665 nm. Since the electron withdrawing group 1,3,4-oxadiazole was formed after the desulfurization reaction, the fluorescence intensity of NCS-BOD-OCH 3 decreased significantly in THF/H 2 O (v/v, 1 : 1, buffered with 10 mM PBS pH = 7.4), which is visible to the naked eye with an obvious color change. NCS-BOD-OCH 3 can realize the two-photon up-converted fluorescence emission. The low detection limit was calculated from the titration results, with the figure for NCS-BOD-OCH 3 /ClO - being 1.15 × 10 -6 M. The result of living cell imaging experiment demonstrated that NCS-BOD-OCH 3 can successfully detect ClO - in living cells and can serve as a NIR mitochondrial imaging agent. It is an excellent platform for developing NIR ClO - fluorescent probes.