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Three novel fluorescent Zn(II) frameworks, namely [Zn(DPA)(NDA)]2·2DMF (1), [Zn2(DPA)(OBA)2]·2DMF·4H2O (2) and [Zn(DPA)(HNTB)]·H2O (3) (DPA = 2,5-di(pyridin-4-yl)aniline, H2NDA = 1,4-naphthalenedicarboxylic acid, H2OBA = 4,4′-oxydibenzoic acid, H3NTB = 4,4′,4′′-nitrilotribenzoic acid, DMF = N,N-dimethylformamide), were successfully fabricated and structurally characterized. Due to the variety of organic linkers, 1–3 exhibit varied topologies: 1 is a 4-c three-dimensional (3D) framework with {65·8} topology, 2 is a 6-c 3D net with point symbol of {44·610·8}, and 3 is a 4-c two-dimensional network that further stacks into a 3D structure by hydrogen bonding interactions with {44·62} topology. Experiments related to fluorescence show that 1–3 can be utilized to quickly identify specific anions of CrO42−/Cr2O72−, and organic molecules such as 2,4,6-trinitrophenol and benzaldehyde. [ABSTRACT FROM AUTHOR]

Carbon dots have promising prospects for analytical and monitoring purposes, but are greatly hindered by the aggregation-induced luminescence quenching owing to the π–π interaction or the non-radiation-excited radical complex formation. Herein hydrothermally prepared orange-yellow fluorescent carbon dots (O-CDs) show an aggregation-induced fluorescence enhancement (AIFE) with Cu2+ owing to the complexation of Cu(II) and the O-CDs. Cu2+ was then sensitively and selectively detected in the linear range from 0.02 to 30 μM with the detection limit of 14 nM, making the detection of Cu2+ in fresh water and E. coli lysate successful, showing that the as-prepared O-CDs could be well applied to the environmental monitoring of heavy metals. [ABSTRACT FROM AUTHOR]

Two complexes, namely [Zn(bpeb)(sda)] (1) and [Zn(poly-bpeb)(sda)] (2), were synthesized by an organic ligand with an extensively conjugated system, bpeb = 1,4-bis[2-(3-pyridyl) vinyl]-benzene, H2sda = sulfonyldibenzoic acid and d10 metal centers Zn2+. Structural analysis revealed that compound 1 was nonporous and possessed 7-fold interpenetrated three-dimensional (3D) frameworks constructed from one-dimensional (1D) Zn-bpeb and Zn-sda chains. Interestingly, due to the short distance between the vinyl groups from two neighboring bpeb ligands, compound 1 could undergo a photochemical [2 + 2] polymerization reaction to generate 2 in a single-crystal to single-crystal (SCSC) manner under the irritation of UV. Moreover, the organic polymer in 2 could be depolymerized by heating to realize the reversible transformation from 2 to 1. Furthermore, both compounds 1 and 2 could be used as fluorescent sensors for 2,4,6-trinitrophenol (TNP) with high selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

Plasmonic photocatalysis on bimetallic heterostructures via plasmonic hot electrons (eph−) has received significant attention owing to their ability to harvest solar energy and high catalytic activities, whereas the mechanism of the eph− transfer at the metal–metal interfaces is still not completely understood owing to the chemical interface damping. Here, the eph− transfer from Au nanospheres (Au NSs) to the Pt interface is directly imaged by plasmon resonance light scattering (PRLS) microscopy. Under the plasmonic resonance illumination (PRI), eph− generated from Au NSs reduced PtCl62− to Pt(0) atoms, which are deposited on the surface of Au NSs to form a porous Au@Pt porous core–shell nanostructure (Au@Pt NS), and thus eph− could persistently transfer across the Au–Pt interface longer than 20 nm to further improve hydrogen evolution reaction (HER), which is further confirmed by ultrafast transient absorption spectra and transient photocurrent responses. This study promotes the understanding of the distance of eph− transfer at metal–metal interfaces to improve the separation efficiency of hot carriers in plasmonic-enhanced applications. [ABSTRACT FROM AUTHOR]

A new tetrapyrazole-modified tetraphenylethene (TPE) ligand L was designed and found to display "turn-on" fluorescence when it combines with Ag+ ions in dilute solution by restricting intramolecular rotation of TPE. A series of Ag complexes 1–7 were obtained, and they exhibit excellent fluorescence properties in the solid state. Compared with PF6−, the silver complex with the CF3SO3− anion can further enhance its fluorescence due to the transformation of its structure from Ag2L (2) to Ag4L2 (3). As zero-dimensional complexes, 1 and 3 have excellent piezochromic properties with a color change from blue to green. Furthermore, structural changes of 1 and 3 to the corresponding three-dimensional frameworks 4 and 5 occur upon immersing in ethanol. In addition, 1 can act as a potential fluorescent probe for sensing nitrile compounds. [ABSTRACT FROM AUTHOR]

Highly sensitive colorimetric detection of silver(i) ions (Ag+) at the single-particle level was developed based on the color of a gold nanoparticle (AuNP) assembly captured by dark-field microscopy (DFM) imaging. Formation of C–Ag+–C bonding between cytosines was utilized to induce interparticle coupling of AuNPs modified with single-strand DNA, resulting in a color change as the signal transduction to quantify Ag+ under DFM imaging. This method allowed visual quantitation of Ag+ in the range of 0.05 nM–250.00 nM and a detection limit of 28.8 pM was achieved. Furthermore, we demonstrated its applicability for the colorimetric detection of Ag+ in a small quantity of real samples, showing the good potential of this developed method for environmental monitoring and drug quality control. [ABSTRACT FROM AUTHOR]

A simple protocol for in situ growth of Cu2−xSe nanoparticles on graphene oxide hybrids (Cu2−xSe/rGO) acting as an efficient nanozyme is developed and thus a sensitive visual detection method of cancer cells is proposed. The Cu2−xSe/rGO heterogeneous nanomaterials have been proven to exhibit high peroxidase-like activity to catalyze the reaction of the peroxidase substrate in the presence of hydrogen peroxide. Herein, we used Cu2−xSe/rGO as a signal transducer to develop a colorimetric assay for the direct detection of cancer cells and a total of 63 cancer cells (MCF-7) can be distinguished by naked-eye observation. The results showed that the Cu2−xSe/rGO hybrids could be the promising nanozyme mimetics for potential applications in bioanalytical fields. [ABSTRACT FROM AUTHOR]

Clear doughnut-shaped far-field scattering patterns (DNSPs) for gold regular hexagonal nanoplates (AuHNPs) larger than 500 nm (distance between the two opposite edges) have been observed by dark-field microscopy imaging. This phenomenon was attributed to the edge effect, which can be further applied for reaction process monitoring. [ABSTRACT FROM AUTHOR]

Besides its widely known role as an endogenous antioxidant in scavenging free radicals, glutathione (GSH) can also play the role of prooxidant and promote CuO-induced formation of hydroxyl radicals to light up a fluorescent signal through Cu(i)–O2 chemistry without requiring additional H2O2. This approach is independent of the mechanisms of enzyme mimics, such as the well-known oxidase and peroxidase mimetics, providing a new method to simply and effectively analyze intracellular GSH. [ABSTRACT FROM AUTHOR]

Selenium nanoparticles (SeNPs) with strong green scattering light serving as light scattering nanoprobes for dark-field microscopy imaging are developed for the first time. The SeNPs show good stability, excellent biocompatibility, and high light-producing power, and can precisely and specifically target cancer cells with overexpressed nucleolin (NCL) after modification with aptamers, revealing that the SeNPs can act as a good light scattering nanoprobe for bioimaging and biolabeling. [ABSTRACT FROM AUTHOR]

Herein, dual-functionalized reduced graphene oxide (rGO) hybrids (rGO/AuNP/luminol) with gold nanoparticles (AuNPs) and luminol were prepared viaπ–π conjugation and electrostatic interaction. The as-prepared rGO/AuNP/luminol hybrids exhibited enhanced and long-persistent chemiluminescence (CL) performance without decay for one hour when mixed with H2O2; this was due to the generation of ṖOH, O2Ṗ−, 1O2, and π–C=CṖ species. A sensitive and selective CL sensor based on the rGO/AuNP/luminol hybrid CL enhancing system was developed for cholesterol quantitation in the linear range from 0.71 to 11.43 μM with a detection limit of 0.55 μM. Furthermore, the proposed method was successfully exploited for the determination of cholesterol in human serum samples. [ABSTRACT FROM AUTHOR]

Photoluminescent (PL) carbon quantum dots (CQDs), in which Cu(i) was doped stably owing to their specific zigzag edge structure, were used for catalyzing the Huisgen 1,3-dipolar cycloaddition between azides and alkynes, the prototypical reaction of “click chemistry”. The results showed the great potential of the as-prepared CQDs in catalysis chemistry applications. [ABSTRACT FROM AUTHOR]

Nonstoichiometric copper chalcogenides with heavy copper vacancies can be used as an effective photo-activated catalyst for the Huisgen [3+2] cycloaddition reaction as Cu(i) can be released corresponding to holes (Cu-defects) under light irradiation. These strategies expand new possibilities for carrying out prototypical click chemistry in the presence of functional groups. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are well known as photo-thermal agents for the ablation of tumor cells, but are limited in the application of photo-thermal therapy (PTT) owing to their low molar extinctions. By coupling the photo-thermal effects of CNTs and the intense localized surface plasmon resonance (LSPR) in the near-infrared (NIR) region of Cu2−xSe nanoparticles (NPs), herein we developed a highly efficient PTT nanohybrids agent by in situ growth of Cu2−xSe NPs on the acid-functionalized CNTs at room temperature. The as-prepared Cu2−xSe/CNT nanohybrids have been found to have intense LSPR in the NIR region and good photo-thermal conversion properties. Moreover, possessing good biocompatibility and dispersibility, the nanohybrids could easily be internalized by cancer cells, and show smart photo-thermal performance, properties which were then successfully applied for photo-thermal therapy in vitro, indicating that the Cu2−xSe/CNT nanohybrids could be a potential photo-thermal therapy agent for the ablation of tumor cells. [ABSTRACT FROM AUTHOR]

The detection of nitroaromatic explosives is of great importance owing to their strong explosive power and harmfulness in terms of the environment, homeland security and public safety. Herein, rare earth-doped carbon dots with multifunctional features were firstly prepared by simply keeping the mixture of terbium(iii) nitrate pentahydrate and citric acid at 190 °C for 30 min. The as-prepared terbium doped carbon dots (Tb-CDs), through a rapid and simple direct carbonization route, have a size of about 3 nm, and exhibit excitation wavelength dependent emission of blue fluorescence, are stable, and can be applied for the selective and colorimetric detection of 2,4,6-trinitrophenol (TNP) in the range of 500 nM–100 μM with a limit of detection of 200 nM based on the inner filtering effect (IFE) of the excitation and emission bands of Tb-CDs by TNP and the electron transfer (ET) from Tb-CDs to TNP, giving a precise and highly reproducible result for detecting complex water samples. [ABSTRACT FROM AUTHOR]

Photocatalytic semiconductors have attracted considerable attention due to their applications in the degradation of organic pollutants. However, the low solar-light harvesting and high electron–hole recombination rate limit the efficiency of photocatalysts. The newly developed localized surface plasmon resonance (LSPR) can offer a new opportunity to overcome the limited efficiency to some extent. In this study, heterojunctions (Cu2−xSe–g-C3N4) incorporating plasmonic semiconductor Cu2−xSe with graphitic carbon nitride (g-C3N4) are proposed as visible light photocatalysts. Their photocatalytic performance is tested and proven via the degradation of methyl blue (MB) in an aqueous solution. When the mass percentage composition of Cu2−xSe reached 60%, the as-prepared composite exhibited the highest photocatalytic activity, which was almost 6.1 and 2.8 times as high as that of individual Cu2−xSe and g-C3N4, respectively. The remarkable photocatalytic efficiency of such Cu2−xSe–g-C3N4 heterojunctions under visible light illumination due to both plasmonic enhancement of the catalyst and synergetic effect of the co-catalyst is shown. This work can provide a new methodology to develop stable and highly efficient heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Full understanding and easy construction of specific biosensing principles is necessary for disease diagnostics and therapeutics in the hope of creating new types of biosensors. Herein, we developed a new conceptual nanobiosensing platform by coupling nanometal surface energy transfer (NSET) and photo-induced electron transfer (PET) with polydopamine-embedded Cu2−xSe nanoparticles (Cu2−xSeNPs@pDA) and DNA-conjugated fluorescent organic dyes. The new prepared Cu2−xSeNPs@pDA has intense and broad localized surface plasmon resonance (LSPR) absorption over UV to near infrared (NIR) wavelengths, with different affinities toward ssDNA versus dsDNA. It also exhibits a high multiplexed fluorescence quenching ability, and thus can act as an acceptor in the energy transfer and electron transfer interactions between Cu2−xSeNPs@pDA and fluorescent organic dyes. As a proof of concept, a new biosensing platform has been successfully developed to target biomacromolecules such as DNA and proteins, in which the NSET and PET interactions between Cu2−xSeNPs@pDA and three different DNA-conjugated fluorescent dyes have been identified using steady-state and time-resolved fluorescence. A simple mathematical model was further applied to simulate the respective contributions of the coexisting NSET and PET to the total quenching observed for each DNA-conjugated dye in this sensing system. This study highlights the importance of understanding the mechanistic details of NSET and PET coupling processes, and the disclosed coupling mechanism of NSET and PET (NSET©PET) in the systems of Cu2−xSeNPs@pDA with wide wavelength range dyes provides new opportunities for sensitive biosensing applications. [ABSTRACT FROM AUTHOR]

Three extended three-dimensional (3D) magnetic metal–organic frameworks (MMOFs), {[Mn3(H2O)2(atz)4Cl2]·2CH3OH}n (1), {[Mn2(H2O)(atz)2(ip)]·C2H5OH}n (2) and {[Mn2(H2O)2(atz)(btc)]·3H2O·0.7CH3OH}n (3) (atz− = 5-aminotetrazolate, ip2− = isophthalate and btc3− = 1,3,5-benzenetricarboxylate), were respectively obtained by varying the coligands with different numbers of functionalities and molecular topology, and structurally and magnetically characterized. Complex 1 exhibits an eight-connected 36·418·53·6 topological network with linear MnII3 subunits periodically linked by ditopic atz− connectors. Complex 2 possesses a pillared-layer framework constructed from undulated {Mn2(atz)2} layers and bidirectional ip2− spacers. By contrast, 3 consists of bent one-dimensional (1D) {Mn(atz)} ribbons, which are crosslinked through the carboxylate groups of tripodal btc3− connectors to generate a 3D architecture. Structural analysis reveals that the interesting motifs of 1–3 and their diverse linkages are significantly dominated by the cooperate coordination of the mixed ligands to the octahedral MnII ion. Magnetically, 1 displays ferrimagnetic behavior resulting from the periodic arrangement of the net moment in the MnII3 subunit, which is scarcely observed in the homometallic azolate systems. Complex 2 features unusual coexistence of spin-canted antiferromagnetic behavior and field-induced spin-flop transition due to the asymmetric magnetic superexchange within the two-dimensional (2D) {Mn2(atz)2} sublayer. By contrast, only antiferromagnetic ordering is observed in the 1D {Mn(atz)} ribbon of 3. These interesting results suggest that the diverse structural motifs by the cooperate coordination of octahedral MnII ion with the N-rich tetrazolyl group can more significantly direct the magnetic behaviors and could be hopefully utilized upon the construction of novel MMOFs. [ABSTRACT FROM AUTHOR]

Three novel fluorescent Zn(II) frameworks, namely [Zn(DPA)(NDA)] 2 ·2DMF (1), [Zn 2 (DPA)(OBA) 2 ]·2DMF·4H 2 O (2) and [Zn(DPA)(HNTB)]·H 2 O (3) (DPA = 2,5-di(pyridin-4-yl)aniline, H 2 NDA = 1,4-naphthalenedicarboxylic acid, H 2 OBA = 4,4'-oxydibenzoic acid, H 3 NTB = 4,4',4''-nitrilotribenzoic acid, DMF = N , N -dimethylformamide), were successfully fabricated and structurally characterized. Due to the variety of organic linkers, 1-3 exhibit varied topologies: 1 is a 4-c three-dimensional (3D) framework with {6 5 ·8} topology, 2 is a 6-c 3D net with point symbol of {4 4 ·6 10 ·8}, and 3 is a 4-c two-dimensional network that further stacks into a 3D structure by hydrogen bonding interactions with {4 4 ·6 2 } topology. Experiments related to fluorescence show that 1-3 can be utilized to quickly identify specific anions of CrO 4 2- /Cr 2 O 7 2- , and organic molecules such as 2,4,6-trinitrophenol and benzaldehyde.

Two complexes, namely [Zn(bpeb)(sda)] (1) and [Zn(poly-bpeb)(sda)] (2), were synthesized by an organic ligand with an extensively conjugated system, bpeb = 1,4-bis[2-(3-pyridyl) vinyl]-benzene, H 2 sda = sulfonyldibenzoic acid and d 10 metal centers Zn 2+ . Structural analysis revealed that compound 1 was nonporous and possessed 7-fold interpenetrated three-dimensional (3D) frameworks constructed from one-dimensional (1D) Zn-bpeb and Zn-sda chains. Interestingly, due to the short distance between the vinyl groups from two neighboring bpeb ligands, compound 1 could undergo a photochemical [2 + 2] polymerization reaction to generate 2 in a single-crystal to single-crystal (SCSC) manner under the irritation of UV. Moreover, the organic polymer in 2 could be depolymerized by heating to realize the reversible transformation from 2 to 1. Furthermore, both compounds 1 and 2 could be used as fluorescent sensors for 2,4,6-trinitrophenol (TNP) with high selectivity and sensitivity.

A simple protocol for in situ growth of Cu 2-x Se nanoparticles on graphene oxide hybrids (Cu 2-x Se/rGO) acting as an efficient nanozyme is developed and thus a sensitive visual detection method of cancer cells is proposed. The Cu 2-x Se/rGO heterogeneous nanomaterials have been proven to exhibit high peroxidase-like activity to catalyze the reaction of the peroxidase substrate in the presence of hydrogen peroxide. Herein, we used Cu 2-x Se/rGO as a signal transducer to develop a colorimetric assay for the direct detection of cancer cells and a total of 63 cancer cells (MCF-7) can be distinguished by naked-eye observation. The results showed that the Cu 2-x Se/rGO hybrids could be the promising nanozyme mimetics for potential applications in bioanalytical fields.

Besides its widely known role as an endogenous antioxidant in scavenging free radicals, glutathione (GSH) can also play the role of prooxidant and promote CuO-induced formation of hydroxyl radicals to light up a fluorescent signal through Cu(i)-O2 chemistry without requiring additional H2O2. This approach is independent of the mechanisms of enzyme mimics, such as the well-known oxidase and peroxidase mimetics, providing a new method to simply and effectively analyze intracellular GSH.

Full understanding and easy construction of specific biosensing principles is necessary for disease diagnostics and therapeutics in the hope of creating new types of biosensors. Herein, we developed a new conceptual nanobiosensing platform by coupling nanometal surface energy transfer (NSET) and photo-induced electron transfer (PET) with polydopamine-embedded Cu(2-x)Se nanoparticles (Cu(2-x)SeNPs@pDA) and DNA-conjugated fluorescent organic dyes. The new prepared Cu(2-x)SeNPs@pDA has intense and broad localized surface plasmon resonance (LSPR) absorption over UV to near infrared (NIR) wavelengths, with different affinities toward ssDNA versus dsDNA. It also exhibits a high multiplexed fluorescence quenching ability, and thus can act as an acceptor in the energy transfer and electron transfer interactions between Cu(2-x)SeNPs@pDA and fluorescent organic dyes. As a proof of concept, a new biosensing platform has been successfully developed to target biomacromolecules such as DNA and proteins, in which the NSET and PET interactions between Cu(2-x)SeNPs@pDA and three different DNA-conjugated fluorescent dyes have been identified using steady-state and time-resolved fluorescence. A simple mathematical model was further applied to simulate the respective contributions of the coexisting NSET and PET to the total quenching observed for each DNA-conjugated dye in this sensing system. This study highlights the importance of understanding the mechanistic details of NSET and PET coupling processes, and the disclosed coupling mechanism of NSET and PET (NSET©PET) in the systems of Cu(2-x)SeNPs@pDA with wide wavelength range dyes provides new opportunities for sensitive biosensing applications.