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In this work, a new Co metal-organic framework (Co(pbda)(4,4-bpy)·2H 2 O] n Co-MOF) (bpy = 4,4-bipyridine; H 2 pbda = 3-(pyridine-3-yloxy)benzene-1,2-dicarboxylic acid) was synthesized under hydrothermal conditions and then applied as the active materials for high performance hydrogen peroxide sensor. Single-crystal X-ray analysis reveals a three-dimensional supramolecular architecture with a uninodal 4-connected net with the gis topology. The cyclic voltammogram of the Co-MOF modified GC electrode shows a pair of reduction peaks at ca. −0.40 V in 0.1 M NaOH solution corresponding to Co III -MOF/Co II -MOF couple. The amperometric response demonstrates the high electrocatalytic activity of the Co-MOF modified GC electrode towards H 2 O 2 reduction with a wide linear range from 5 μM to 9.0 mM, a low detection limit of 3.76 μM and a high sensitivity of 83.10 μA mM −1 cm 2 at an applied potential of −0.40 V. Moreover, the favourable selectivity and long-term stability were also obtained. Additionally, it was found that Co-MOF possessed highly efficient intrinsic peroxidase-like activity so that it could catalyze H 2 O 2 to produce hydroxyl radical, which oxidized peroxidase substrate (terephthalic acid) to produce colour. Thus, this new Co-MOF has a great potential for applications in H 2 O 2 electrochemical detection. [ABSTRACT FROM AUTHOR]

Wereport here the theoretical analysis of the mechanism and regioselectivityof the direct insertion of silane moieties into the C–N bondof N-heterocyclic carbenes leading to eventual ring expansion andformation of diazasilinanes. Symmetrically and unsymmetrically substitutedNHC have been considered to account for some experimental observations.These reaction steps include (1) Si–H bond activation of thesilane at the NHC; (2) amide transfer to the silicon atom to yielda six-membered intermediate; (3) hydride or phenyl group transferto the carbon atom to give the product. In addition, the computedresults over a variety of silanes agree with experimental evidenceand suggest that both steric and electronic effects play a crucialrole in the regioselectivity outcome and the involvement of operativeintermediates in the reaction pathway. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mechanisms of gold (I)-catalyzed cycloisomerization were investigated. [•] Three possible mechanisms for title reaction are considered. [•] Theoretical investigation was performed to explain the difference of reactivity. [•] Water-assisted [1,2]-H shift for title reaction was located. [•] Calculated results are consistent with the experimental observations. [ABSTRACT FROM AUTHOR]

The mechanisms of PtCl2-catalyzed rearrangementof cyclopropenesto allenes have been investigated using density functional theorycalculations carried out at the B3LYP/6-31G(d,p) (LANL2TZ(f) for Pt)level of theory. The solvent effect was taken into account by B3LYP/6-311(d,p)(LANL2TZ(f) for Pt) single-point calculations with the integral equationformalism polarizable continuum model (IEFPCM) in dichloromethane.The radii and nonelectrostatic terms were taken from Truhlar and co-workers’universal solvation model (SMD). Three pathways which lead to theformation of allene via a [1,2]-C–C bond migration (regioselectivity)and C–Si bond migration were performed. Our calculations suggestthe following. (1) The major pathway of the cycle involves an initial[1,2]-silyl shift leading to a platinum intermediate. A subsequent[1,2]-C–C bond shift of this intermediate then provides thecorresponding allenes. (2) Due to the consequence of an interactionbetween the Lewis acidic platinum and the allene, the rearrangementof α-alkoxy-substituted cyclopropenes does not give the alleneas the final product. (3) The calculations suggest that the electroniceffect of a silyl substituent on the cyclopropene is essential forthis reaction. Furthermore, the silyl groups provide not only theβ-cation-stabilizing effect but also a facile migration groupfor the whole reaction. [ABSTRACT FROM AUTHOR]

The mechanisms of the gold(I)-catalyzed rearrangementof homopropargylsulfoxides have been investigated using density functional theorycalculations done at the B3LYP/6-31G(d, p) (SDD for Au) level of theory.Solvent effects on these reactions have been explored by calculationsthat included a polarizable continuum model (PCM) for the solvent(CH2Cl2). Two plausible pathways which leadto the formation of benzothiepinones or benzothiopines via an α-carbonylAu carbenoid through 5-exo-dig cyclization or 6-endo-dig cyclization were proposed. Our calculation resultssuggested the following. (1) The first step of the cycle is nucleophilicaddition of the sulfoxide oxygen onto the triple bond to form an alkenylgold intermediate through 5-exo-dig cyclization or6-endo-dig cyclization. The alkenyl gold speciesis then capable of pushing out the sulfide moiety, forming an α-carbonylAu carbenoid. Finally, α-carbonyl Au carbenoids undergo intramolecularFriedel–Crafts alkylation to produce the observed productsand liberate the cationic gold(I) catalyst. (2) When the alkyne issubstituted with an electron-withdrawing group, 5-exo-dig cyclization of the nucleophile onto the internal carbon of thealkyne is favored. On the other hand, when the alkyne is substitutedwith an alkyl group, 6-endo-dig cyclization of thenucleophile onto the internal carbon of the alkyne is favored. (3)For 6-endo-dig cyclization, an intramolecular reactionof the α-carbonyl Au carbenoid with the benzene ring was therate-determining step. However, migration of the hydrogen atom resultingin the formation of the final product was the rate-determining stepfor 5-exo-dig cyclization. (4) In the presence ofwater, the direct [1,5]-hydride shift has been changed into a deprotonation/protonationprocess. A very easy deprotonation process was found in the case ofwater. The higher activation free energies for the protonation processindicate that this step became the rate-determining one. [ABSTRACT FROM AUTHOR]

The natural polymer cellulose exhibits significant potential for various applications due to its unique optical, electronic, and chemical properties. However, the use of cellulose materials in luminescent applications has been relatively limited. This study aims to develop a simple and efficient method to enhance the fluorescence of cellulose materials by incorporating rare earth elements, thereby expanding their range of applications. In this work, we synthesized hybrid cellulose materials by grafting Eu‐bpy (H2bpydc=2,2‐bipyridine‐5,5‐dicarboxylic acid) onto the surface of cellulose fibers through a straightforward post‐processing procedure, resulting in materials with excellent fluorescence properties. By leveraging the abundant hydroxyl groups on the surface of cellulose fibers, Eu‐bpy@CF exhibits high luminescence in response to relative humidity and pH changes, with a noticeable color shift from light red to red visible to the naked eye. Consequently, these materials were further applied in the construction of smart fluorescent switches for the highly accurate and selective detection of phenylenediamine. Our research provides a simple approach to creating environmentally responsive handheld fluorescent papers and expands the diversity of rare‐earth cellulose fibers for developing new fluorescent materials with smart functions. [ABSTRACT FROM AUTHOR]

With a rapid expansion in applications of epoxy resins (EP) and derived composites, there is a high demand for improving their flame retardant and dielectric properties. In this work, a facile and convenient strategy for loading a dimethyl methylphosphonate (DMMP) flame retardant into the channels of ZIF-8 (zeolitic imidazolate framework) was developed, followed by the assembly of a hybrid ZIF-8@DMMP material with epoxy resin (EP). The obtained MOF-containing hybrid EP composites, abbreviated as 820/EP (with 20 wt% ZIF-8) and 8 FR20/EP (with 20wt% ZIF-8@DMMP), were fully characterized and shown to feature superior flame retardant behavior, contributing to an enhanced safety of such material in terms of total smoke suppression, lower levels of total heat release and carbon monoxide generation. The results demonstrated that the formation of an intumescent dense char layer restrained further combustion, thus enabling this composite material to feature a better flame retardant performance. Besides, the composite exhibited a dielectric permittivity and dielectric loss of as low as 3.0 at a high frequency, which significantly outperforms the neat epoxy resin. This work thus showcases a simple and efficient route to enhance dielectric and flame retardant properties of polymeric epoxy resins, while merging the inherent porosity of ZIF-8 and traditional flame retardant behavior of DMMP. [ABSTRACT FROM AUTHOR]

Post-synthetic modification of metal–organic frameworks (MOFs) and fabrication of hybrid composites are currently hot topics in the development of new functional materials. In this study, a facile and direct approach for coupling of lanthanide MOFs with epoxy silanes was developed, providing an access to a new series of functional composites. Two types of commercially available epoxy silane, namely 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECTMS) and (3-glycidoxypropyl)methyl diethoxysilane (KH563), were used to modify Ln-BTB MOFs ([Ln(BTB)(H2O)]n·2n(C6H12O); Ln = Tb or Eu0.001Tb0.999; H3BTB = 1,3,5-benzenetrisbenzoic acid) via covalent grafting involving mechanical grinding, epoxide coupling and curing reactions. The fabricated composites (Tb-BTB@ECTMS, Eu0.001Tb0.999-BTB@ECTMS, Tb-BTB@KH563, Eu0.001Tb0.999-BTB@KH563) and their Ln-MOF precursors were fully characterized, including a detailed study of their stability and fluorescence properties. The obtained composites show high thermal and solution stability, under boiling water conditions and in a wide pH range of 1–12. Application of the composites as temperature sensors in the 197–297 K and 273–343 K temperature ranges was explored in detail, revealing a remarkable sensing behavior. For example, Tb-BTB@ECTMS shows a maximum relative sensitivity (Sr) of 6.85% K−1 at 343 K. Eu0.001Tb0.999-BTB@ECTMS represents a white-light emission material with the CIE coordinates (0.3194, 0.3049) that are very close to those of white light, along with good temperature sensing performance and a relative sensitivity of 4.32% K−1 at 297 K. An enhanced performance of the composites in comparison with the parent MOF materials as well as the mechanism of energy transfer were rationalized by DFT calculations. By unveiling a facile and efficient method for improving the stability of luminescent MOFs, via post-synthetic grafting with epoxy silanes, the present study will stimulate further research at the interface of materials chemistry, MOF design, photoluminescence and temperature sensing. [ABSTRACT FROM AUTHOR]

A new quinoline-based probe was designed that shows one-photon ratiometric and two-photon off-on changes upon detecting Cd2+. It exhibits fluorescence emission at 407 nm originating from quinoline groups in Tris-HCl (25 mm, pH 7.40), H2O/EtOH (8:2, v/v). Coordination with Cd2+ causes quenching of the emission at 407 nm and simultaneously yields a remarkable redshift of the emission maximum to 500 nm with an isoemissive point at 439 nm owing to an intramolecular charge-transfer mechanism. Thus, dual-emission ratiometric measurement with a large redshift (Δλ=93 nm) and significant changes in the ratio (F500/F439) of the emission intensity (R/R0 up to 27) is established. Moreover, the sensor H2L displays excellent selectivity response, high sensitive fluorescence enhancement, and strong binding ability to Cd2+. Coordination properties of H2L towards Cd2+ were fully investigated by absorption/fluorescence spectroscopy, which indicated the formation of a 2:1 H2L/Cd2+ complex. All complexes were characterized by X-ray crystallography, and TD-DFT calculations were performed to understand the origin of optical selectivity shown by H2L. Two-photon fluorescence microscopy experiments have demonstrated that H2L could be used in live cells for the detection of Cd2+. [ABSTRACT FROM AUTHOR]

[Display omitted] • The "silver effect" in regiodivergent Au-catalyzed hydroamination of terminal alkynyl sulfamides was investigated by DFT. • The regioselectivity is mainly controlled by "silver effect" rather than the steric effect. • A gem-diaurated structure with a three-center two-electron bond was observed instead of the σ,π-digold complex. The mechanism and "silver effect" in regiodivergent gold-catalyzed hydroamination of terminal alkynyl sulfamides have been explored by the density functional theory (DFT) in the model systems composed of [AuCl(Ph 3 P)]/AgOTf (series A), AuCl(Ph 3 P)]/K 2 CO 3 (series B) and [AuCl(Ph 3 P)]/Ag 2 CO 3 (series C). Our results clearly showed that the regioselectivity of the terminal alkynyl sulfamides is mainly controlled by true involvement of Ag in the catalysis when using different silver salts as a component of gold-based catalytic system, rather than the steric effect. In the [AuCl(Ph 3 P)]/AgOTf and [AuCl(Ph 3 P)]/Ag 2 CO 3 catalytic systems, the formation of π-activation or σ-gold-π-silver intermediates turns more favorable the 6-endo-dig cyclization in comparison with the 5-exo-dig pathway. On the other hand, the 5-exo-dig cyclization involving a three-membered Au-C-Au ring activated alkyne intermediate is likely the major pathway for the [AuCl(Ph 3 P)]/K 2 CO 3 catalytic system. Furthermore, the regioselectivity and its origin as well as the rationalization of "silver effect" are also examined and discussed in detail. [ABSTRACT FROM AUTHOR]

• Ligand-controlled mechanisms and chemo-, regio- and stereoselectivities were theoretically investigated in the Pd-catalyzed semireduction of allenamides. • Theoretical evidence suggests that an η 1- η 3- η 1 interconvertible intermediate play a vital role in determining the selectivity. • Hydride insertion is the first regioselective and stereoselective step for the formation of production. • Independent gradient model based on hirshfeld partition (IGMH) and atoms-in-molecules (AIM) analysis reveals that the regioselectivity is influenced by the difference in noncovalent interactions in XPhos and BINAP ligand systems. The ligand-controlled mechanisms and chemo-, regio- and stereoselectivities were theoretically investigated in the Pd-catalyzed semireduction of allenamides. Two different ligands, including monodentate XPhos and bidentate BINAP, were selected as model systems in the DFT calculations. For both types of ligand systems, the obtained results clearly indicate that the first step of the reaction involves the formation of a Pd-hydride intermediate via the oxidative addition of formic acid to Pd(II) precursor. For a monodentate XPhos ligand, the hydride insertion between a Pd-hydride intermediate and allenamide generates an η 3-allyl palladium intermediate and gives a 1,2-semireduction product through the β -H and reductive eliminations. In the reaction with BINAP, an η 3-allyl palladium intermediate is converted into a more stable η 1-allyl palladium intermediate, leading to the 2,3-semireduction product via the β -hydride elimination. The obtained theoretical evidence suggests that an η 1- η 3- η 1 interconvertible intermediate plays a vital role in determining the selectivity. Furthermore, the analysis of independent gradient model based on Hirshfeld partition (IGMH) as well as atoms-in-molecules (AIM) analysis indicate that the regioselectivity and stereoselectivity are influenced by different CH···π and π···π stacking interactions. The present work contributes to the understanding of the mechanisms and may assist in the design of prospective catalysts to control the regio- and stereoselectivities in this type of important organic transformations. [Display omitted] [ABSTRACT FROM AUTHOR]

Triethylene diamine (DABCO) has the characteristic of being hydrophilic and exhibits a color change in air because its N atom can interact with H2O and CO2. To understand these phenomena, herein, theoretical calculations on the intermolecular interactions between DABCO and H2O (or CO2) were carried out at the M06-2X/aug-cc-pVDZ level without and with the counterpoise method, and single-point calculations at the CCSD(T)/aug-cc-pVDZ level were also performed. The electron donating ability of DABCO was revealed by the molecular surface electrostatic potential and Fukui function. The driving forces for the formation of a dimer and trimer were uncovered by EDA analyses. Because DABCO can interact with both H2O and CO2, the formation of hydrogen bonds and tetrel bonds is competitive, and meanwhile, DABCO can interact with H2O and CO2 simultaneously, so the hydrogen bond and tetrel bond can coexist and cooperate with each other. The hydrogen bond and tetrel bond in the dimers and trimers were proven and analyzed by NCI and QTAIM. The results presented here will provide useful insight in understanding the hydrophilic characteristic and the color change of DABCO. [ABSTRACT FROM AUTHOR]

Two novel lanthanide metal–organic framework (Ln‐MOF) luminescent sensors for the detection of picric acid have been successfully assembled. Following a function‐oriented strategy, urea hydrogen‐bonding functional sites were introduced into two MOF frameworks. A structural analysis indicated that the two MOFs have the exact same structure, namely 2D layers with diamond‐shaped holes that are accumulated into a 3D framework through the hydrogen‐bonding interactions between urea and carboxylate groups. Interestingly, only half of the urea units are involved in supporting the MOF framework through N−H⋅⋅⋅O hydrogen‐bonding interactions, whereas the other half are located in the pore channel and act as empty recognition sites. Abundant N−H urea bonds are present in the inner walls of three types of interpenetrating 1D channels. Luminescence studies revealed that the two Ln‐MOFs exhibit high sensitivity, good selectivity, and a fast luminescence quenching response towards picric acid. In particular, the two Ln‐MOFs can be simply and quickly regenerated, and exhibit excellent recyclability. In summary, we have successfully used a function‐oriented strategy to achieve multiple functions in a ligand to construct lanthanide MOF luminescent sensors for the detection of picric acid, thereby providing a potential strategy for the future development of MOF luminescent sensors with a specific target. Explosive detection: Following a function‐oriented strategy, two novel lanthanide metal–organic framework luminescent sensors containing dual‐function urea hydrogen‐bond sites have been successfully assembled, and because of the N−H urea bonds in the inner walls of three types of interpenetrating 1D channels, they exhibit high sensitivity, good selectivity, and a fast luminescence quenching response towards picric acid (see figure). [ABSTRACT FROM AUTHOR]

[Display omitted] • Isoxazoles experience the 6-endo-dig heteroatom-assisted S E Ar to form an alkenyl Au(I) intermediate. • N-phenylbenzaldimine plays an important role in the hydride transfer process. • The NCI reveals that the π-Au+ interaction between Au+ and the phenyl ring rationalized the deuterium labeling study. A detailed theoretical study on the mechanism and regioselectivity of the Au(I)-catalyzed intramolecular electrophilic aromatic substitution (S E Ar) in 4-substituted isoxazole derivatives is reported, using two model substrates, 4-(1-methylpropargyloxy)isoxazole (Series A) and 4-(1-methyl propargylamino)isoxazole (Series B). The obtained theoretical data reveal similar energy profiles in both series for the 6-endo-dig heteroatom-assisted S E Ar to form an alkenyl Au(I) intermediate. Then, in the series A, the 1,3-H-shift assisted by the 4-propargyloxyisoxazole leads to a final product and the catalyst regeneration. In contrast, in the series B, the elimination of proton by N-phenylbenzaldimine additive results in an iminium cation and dihydropyridine. In the next step, a hydride from dihydropyridine is accepted by the iminium cation to furnish pyridinium and N-benzylidenebenzenaminium species. Subsequently, protodeauration leads to a final product and N-phenylbenzylamine along with the catalyst regeneration. In the absence of N-phenylbenzaldimine additive, 4-(1-methylpropargylamino)isoxazole accepts the hydride instead of N-phenylbenzylamine and causes the consumption of the reactants, thus accounting for a low product yield. Furthermore, the regioselectivity and its origin as well as the rationalization of the deuterium labeling experiments are also examined and discussed in detail. [ABSTRACT FROM AUTHOR]

Lanthanide coordination polymers (Ln-CPs) ([Eu(L)2(H2O)]Br·H2O)n (EuBr) and ([TbL2(H2O)2]Br·H2O)n (TbBr) have been synthesised and photoluminescence studies revealed that EuBr and TbBr exhibit a sensitive and fast luminescence quenching response to Fe3+ and picric acid (PA). The quenching effect constant (Ksv) of EuBr for Fe3+ can reach 3974 M−1 and that of TbBr can reach 4249 M−1. The Ksv of PA is calculated for EuBr as 17 000 M−1 and TbBr as 20 200 M−1. The recyclability experiment of the quenching ability of EuBr and TbBr in water can be tested at least 3 times. Thus, the lanthanide based coordination polymers are a good candidate for use as a multi-response luminescent sensor for the quantitative detection of toxic and hazardous substances in the environment. [ABSTRACT FROM AUTHOR]

A new series of lanthanide coordination polymers formulated as [Ln(μ-L)(μ3-L)(H2O)]nXn (Ln/X = Er/Cl (1), Er/Br (2), Tm/Cl (3), Tm/Br (4), Yb/Cl (5), and Yb/Br (6); L = 1,3-bis(4-carboxyphenyl) imidazolium carboxylate(1+)) were solvothermally generated and fully characterized. Single-crystal X-ray diffraction analysis shows that all products possess isomorphous structures that are composed of cationic 1D double chains with encapsulated halide anions. From a topological perspective, such 1D chains can be classified as a binodal 3,5-connected net with a unique topology defined by the point symbol of (3·42)(32·42·53·62·7). All products 1–6 feature a remarkable thermal stability and were applied as highly active heterogeneous catalysts for the coupling reactions between halogenated propylene oxides and CO2 to give the corresponding cyclic carbonates. The reaction conditions, substrate and catalyst scope, and mechanistic features of this catalytic transformation were investigated. High products yields (up to 98%), elevated TONs (up to 3920) or TOFs (up to 326 h−1) were attained under mild reaction conditions. In addition, catalyst 6 can be recycled at least eight times with no loss of catalytic activity. [ABSTRACT FROM AUTHOR]

A novel luminescent microporous lanthanide metal-organic framework (Ln-MOF) based on a urea-containing ligand has been successfully assembled. Structural analysis revealed that the framework features two types of 1D channels, with urea N−H bonds projecting into the pores. Luminescence studies have revealed that the Ln-MOF exhibits high sensitivity, good selectivity, and a fast luminescence quenching response towards Fe3+, CrVI anions, and picric acid. In particular, in the detection of Cr2O72− and picric acid, the Ln-MOF can be simply and quickly regenerated, thus exhibiting excellent recyclability. To the best of our knowledge, this is the first example of a multi-responsive luminescent Ln-MOF sensor for Fe3+, CrVI anions, and picric acid based on a urea derivative. This Ln-MOF may potentially be used as a multi-responsive regenerable luminescent sensor for the quantitative detection of toxic and harmful substances. [ABSTRACT FROM AUTHOR]

Three novel 2D coordination polymers [Tb2(μ4-L)2(μ-HL)(μ-HCOO)(DEF)]n (Tb-L), [Eu(μ4-L)(L)(H2O)2]n (Eu-L), and [Nd(μ4-L)(L)(H2O)2]n (Nd-L) were assembled from the corresponding lanthanide(iii) nitrates and 5 methoxy-(4-benzaldehyde)-1,3-benzenedicarboxylic acid (H2L) as a main multifunctional building block bearing carboxylate and aldehyde functional groups, using H2O/DEF {DEF = N,N-diethylformamide} as a reaction medium. The obtained coordination polymers were isolated as stable microcrystalline solids and fully characterized by elemental analysis, FT-IR spectroscopy, TGA, BET, PXRD, and single-crystal X-ray diffraction methods. Their structures feature intricate 2D metal–organic networks, which were topologically classified as underlying layers with the 4,6L26 (for Tb-L) or sql (for Eu-L and Nd-L) topologies. Besides, a novel series of mesoporous hybrid materials wherein the Tb-L, Eu-L, or Nd-L coordination polymers are covalently grafted into the amine-functionalized SBA-15-NH2 or MCM-41-NH2 matrices (via the formation of Schiff-base groups) was also synthesized and fully characterized. These hybrid materials show high thermal and photoluminescence stability, as well as remarkable chemical resistance to boiling water, and acidic or alkaline medium. Luminescent properties of the parent coordination polymers and derived hybrid materials are investigated in detail, showing that the latter combine the luminescent characteristics (intense green or red emissions and excellent stability) of lanthanide coordination polymers and structural features of ordered mesoporous silica molecular sieves. Moreover, light emitting devices were assembled, by coating the hybrid materials onto the surface of UV-LED bulbs, and showed excellent light emitting properties. [ABSTRACT FROM AUTHOR]

Nine new isostructural 2D lanthanide(iii) coordination polymers (Ln-CPs) with a general formula of {[Ln(Bcpi)2(H2O)]BrxCl1−x·(H2O)}n {Ln = Eu (1–3), Tb (4–6) and Gd (7–9); x = 0, 0.5, 1; Bcpi = 1,3-bis(4-carboxyphenyl)imidazolium} were synthesized by hydrothermal reactions and fully characterized. Single-crystal X-ray structural analysis revealed that this series of Ln-CPs displays 1D channel motifs with encapsulated halide anions, whereas their overall 2D metal–organic networks can be topologically classified as kgd underlying nets. Compounds 1–3 show five characteristic emission lines with maxima at 579, 591, 617, 652 and 701 nm due to the 5D0→7FJ (J = 0–4) transitions, respectively. Besides, compounds 4–6 exhibit four sharp peaks at 487, 544, 582 and 619 nm resulting from the 5D4→7FJ (J = 6–3) transitions. The emission spectra indicate that the halide anions captured in the porous structure could induce the enhancement of photoluminescence. Furthermore, the emission strength and quantum yield increase when the encapsulated choride anions are replaced by bromide anions. In addition, by using the in situ doping method, a series of heterometallic Tb/Eu coordination polymers {[Tb1−xEux(Bcpi)2(H2O)]Cl·(H2O)}n (10) with different contents of metals {x = 0.001, 0.002, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1 and 0.2} were generated, which are tunable yellow light luminescent materials and simultaneously display two major emission bands at 612 and 545 nm due to Eu(iii) and Tb(iii) emission, respectively. [ABSTRACT FROM AUTHOR]

A new and simple fluorescent chemodosimeter, 7-allyl-2-methylquinolin-8-ol, has been synthesized for resumable detection of Hg 2+ . The chemodosimeter displays a highly sensitive and selective response to Hg 2+ with remarkably fluorescence intensity enhanced in aqueous solution containing 0.2% organic cosolvent. Moreover, this resumable chemodosimeter can remove Hg 2+ from water by forming a mercury- containing compound, which could be restored to chemodosimeter 1 by the addition of NaBH 4 . Furthermore, the chemodosimeter has been successfully applied for Hg 2+ detection in drinking water by both one- and two-photon excited fluorescence with low detection limits (<2 ppb). [ABSTRACT FROM AUTHOR]

• Mechanism, regioselectivity and chemoselectivity in the metal-catalyst-controlled selective functionalization of carbazole with diazo-naphthalen-2(1H)-one were studied by DFT calculations. • In the (IPr)AuCl/AgSbF 6 catalytic system, the key intermediate has the strongest electrophilic center, resulting in the C3-alkylation product. • The key intermediates in the Pd(OAc) 2 and Rh 2 (OAc) 4 catalytic systems are much less electrophilic than that of (IPr)AuCl/AgSbF 6 , which explains the generation of the final N-H arylation product. • The distortion/interaction analysis showed that the distortion energy and not the interaction energy plays an important role in the (IPr)AuCl/AgSbF 6 system toward controlling the chemoselectivity. • The chemoselectivity is entirely determined by the interaction energy in the reactions catalysed by Pd(OAc) 2. The interaction and distortion energies are jointly responsible for the chemoselectivity when using the Rh 2 (OAc) 4 catalyst. The mechanism, regioselectivity and chemoseletivity in the metal-catalyst-controlled selective functionalization of carbazole with diazo-naphthalen-2(1H)-one have been explored by the density functional theory (DFT) in the model systems composed of the (IPr)AuCl/AgSbF 6 , Pd(OAc) 2 , and Rh 2 (OAc) 4 catalysts. The DFT calculations reveal that the key intermediate in the (IPr)AuCl/AgSbF 6 system has the strongest electrophilic center compared to those in Pd- or Rh-catalyzed reactions with carbazole, resulting in the C3-alkylation product (series A). For the series B and C (Pd(OAc) 2 and Rh 2 (OAc) 4 catalytic systems), the calculation results disclose that the key intermediates are much less electrophilic than in the series A , which explains the generation of the final N-H arylation product instead of the C3-alkylation product when using these catalytic systems. Another key finding of this study is that the distortion energy and not the interaction energy plays an important role in the series A toward controlling the chemoselectivity. However, the chemoselectivity is entirely determined by the interaction energy in the series B. The interaction and distortion energies are jointly responsible for the chemoselectivity in the series C. The obtained herein results can offer very valuable information toward future design of effective and regioselective catalysts and synthetic protocols for this type of challenging reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mechanism, regioselectivity and chemoselectivity in the metal-catalyst-controlled selective functionalization of carbazole with diazo-naphthalen-2(1H)-one were studied by DFT calculations. • In the (IPr)AuCl/AgSbF 6 catalytic system, the key intermediate has the strongest electrophilic center, resulting in the C3-alkylation product. • The key intermediates in the Pd(OAc) 2 and Rh 2 (OAc) 4 catalytic systems are much less electrophilic than that of (IPr)AuCl/AgSbF 6 , which explains the generation of the final N-H arylation product. • The distortion/interaction analysis showed that the distortion energy and not the interaction energy plays an important role in the (IPr)AuCl/AgSbF 6 system toward controlling the chemoselectivity. • The chemoselectivity is entirely determined by the interaction energy in the reactions catalysed by Pd(OAc) 2. The interaction and distortion energies are jointly responsible for the chemoselectivity when using the Rh 2 (OAc) 4 catalyst. The mechanism, regioselectivity and chemoseletivity in the metal-catalyst-controlled selective functionalization of carbazole with diazo-naphthalen-2(1H)-one have been explored by the density functional theory (DFT) in the model systems composed of the (IPr)AuCl/AgSbF 6 , Pd(OAc) 2 , and Rh 2 (OAc) 4 catalysts. The DFT calculations reveal that the key intermediate in the (IPr)AuCl/AgSbF 6 system has the strongest electrophilic center compared to those in Pd- or Rh-catalyzed reactions with carbazole, resulting in the C3-alkylation product (series A). For the series B and C (Pd(OAc) 2 and Rh 2 (OAc) 4 catalytic systems), the calculation results disclose that the key intermediates are much less electrophilic than in the series A , which explains the generation of the final N-H arylation product instead of the C3-alkylation product when using these catalytic systems. Another key finding of this study is that the distortion energy and not the interaction energy plays an important role in the series A toward controlling the chemoselectivity. However, the chemoselectivity is entirely determined by the interaction energy in the series B. The interaction and distortion energies are jointly responsible for the chemoselectivity in the series C. The obtained herein results can offer very valuable information toward future design of effective and regioselective catalysts and synthetic protocols for this type of challenging reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

A colorimetric and ratiometric fluorescent chemodosimeter for Hg2+ has been developed based on mercury ion-promoted hydrolysis of a naphthalimide-derived aryl vinyl ether. The chemodosimeter displays a highly sensitive and selective response with significant changes in both color (from colorless to jade-yellow) and fluorescence (from blue to green) in PBS buffer solution (containing 1% CH3CN, pH = 7.4). The chemodosimeter exhibits a ratiometric fluorescent response towards Hg2+ with a very low detection limit (3.6 nM), which can be used to detect Hg2+ ions in drinking water. Furthermore, the chemodosimeter has been successfully applied to the imaging of Hg2+ ions in living cells with an emission change from blue to green. [ABSTRACT FROM AUTHOR]

Abstract: The efficiency of fluorescent organic light emitting diodes (FOLEDs) is strongly affected by the fraction of singlet excitons formed. However, the standard statistical value of the single to triplet ratio is 1:3, which implies most of the excitons are invalid in fluorescent emitting devices. Here, we demonstrate the ability of twisted intramolecular charge transfer state (TICT-state) to enhance the occurrence of singlet excitons in a fluorescent emitter that is based on the 9,9′-bianthracene (BA) moiety. The anthracene–anthracene (A–A) linked by a single bond and having perpendicular electronic structure is a charge transfer intersystem crossing π system in excited state. The BA-cored fluorescence emitter (CzBACz) with particular TICT characteristics realizes the electron–hole (e–h) recombination via intramolecular conversion from charge-transfer excitons (immediate precursor) to radiative singlet exciton (final state). For CzBACz-based electroluminescent (EL) device, the singlet generation fraction is more than 25%. [Copyright &y& Elsevier]

An efficient sensor for Zn2橷 Cu2솫 designed based on different binding modes. The sensor displays ratiometric signals for Zn2, due to the Zn2+triggered amide tautomerization; while dual-mode selective behaviors for Cu2귫⺖ from the deprotonation of the amide tautomer. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is emerging as an important biological messenger, and a number of H 2 S fluorescent probes have been developed. However, lanthanide-based luminescent H 2 S probes are rarely reported. Here, a terbium complex-based luminescent H 2 S probe based on the reduction reaction of azide with H 2 S to amine is present. In the presence of H 2 S, the probe shows fluorescence ‘turn-on’ response with 12-fold enhancement of Tb 3+ emission intensity by modulating excited state energy of the antenna based on intramolecular charge transfer (ICT), and it exhibits high selectivity for H 2 S over competitive anions and small-molecule biothiols. Moreover, the long luminescence lifetime of the probe facilitates the implementation of time-delayed experiment, whereby the fluorescence with short lifetime can be readily gated out. The time-gated studies demonstrate that time-gated luminescence detection of the probe toward H 2 S is more precise, not influenced by the background noises caused by fluorescent with short lifetime. [ABSTRACT FROM AUTHOR]

• Mechanism and stereoselectivity in B(C 6 F 5) 3 -catalyzed cyclopropanation of styrenes and aryldiazoacetates were studied by DFT calculations. • A concerted [2 + 1] cycloaddition reaction was identified. • The distortion/interaction analysis showed that the chemoselectivity of cyclopropanation and C-H functionalization were entirely determined by the distortion energy. • The NCI (noncovalent interaction analysis) reveals that the difference in noncovalent interactions is likely responsible for the final stereoselectivity. In this study, the mechanism and stereoselectivity in the B(C 6 F 5) 3 -catalyzed cyclopropanation of styrenes and aryldiazoacetates were studied by the density functional theory (DFT), revealing a number of important observations. (1) The whole reaction entails the coordination of B(C 6 F 5) 3 to the Lewis basic ester site on diazo compound, generating an alkene diazonium species. Loss of dinitrogen affords a resonance stabilized Lewis acid-activated carbene intermediate, which then undergoes a concerted [2 + 1] cycloaddition with styrene to yield a S- isomeric product and regenerate the catalyst. (2) Additional calculation results for E/Z - β -methyl styrene and allyl 4-bromophenyldiazoacetate also support the concerted pathway. (3) For tosylvinylindole substrate, the reaction tends to produce a cyclopropane of the olefin rather than the C H insertion product or cyclopropanation of the 2,3-bond of the indole unit. (4) The calculation results for three ineffective diazo substrates indicate that the activation free energy for the formation of Lewis acid-activated carbene is too high to conduct further reaction. In addition, the distortion/interaction analysis showed that the chemoselectivity of cyclopropanation (C1 or C2) and C H functionalization were entirely determined by the distortion energy, while the stereoselectivity is influenced by the interaction and distortion energies. The obtained results can be of particular significance in homogeneous catalysis toward the design and prediction of organocatalytic molecular systems and [2 + 1] cycloaddition transformations involving alkenes and diazo derivatives. [Display omitted] [ABSTRACT FROM AUTHOR]

A lesson about luminescent Ln ‐ MOFs: A new microporous luminescencent Eu ‐ MOF based on an urea ‐ containing ligand was successfully assembled. The Ln ‐ MOF exhibits a high sensitivity, good selectivity, and a fast luminescence ‐ quenching response towards Fe3+, CrVI anions, and picric acid. Especially in the detection of Cr2O72 ‐ and picric acid, the Ln ‐ MOF exhibited an excellent reusability. Thus, the Ln ‐ MOF can be potentially used as a multiresponsive regenerable luminescence sensor for the quantitative detection of toxic and harmful substances. More information can be found in the Full Paper by W. Liu et al. on page 18769 ff. [ABSTRACT FROM AUTHOR]

A new fluorescent probe for inorganic and organic mercury species based on mercury triggered cleavage reaction is developed. [ABSTRACT FROM AUTHOR]