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In this paper, we employ density functional theory (DFT) simulations to predict the energy conversion efficiency of a novel class of organic dyes based on linear carbon chain (LCC) linkers for application in dye-sensitized solar cells (DSSCs). We investigate the role of the anchoring group, which serves as a bridge connecting the linker and the surface. Specifically, we compare the performance of cyanoacrylic acid, dyes PY-4N and PY-3N, with that of phosphonate derivatives, dyes PY-4NP and PY-3NP, wherein the carboxylic group of the cyanoacrylic moiety is replaced with phosphonic acid. The observed variations in the UV/VIS absorption spectra have a slight impact on the light harvesting efficiency (LHE). Based on the empirical parameters we have taken into account, the electron injection efficiency (Φinj) and electron collection efficiency (ηcoll) values do not impact the short-circuit current density (JSC) values of all the studied dyes. The open-circuit voltage (Voc) is theoretically predicted using the improved normal model (INM) method. Among the dyes, PY-4N and PY-3N demonstrate the highest Voc values. This can be attributed to a more favorable recombination rate value, which is related to the energy gap between the HOMO level of the dyes and the conduction band minimum (CBM) of the surface. Dyes PY-4N and PY-3N are predicted to demonstrate remarkably high photoelectric conversion efficiency (PCE) values of approximately 21.79% and 16.52%, respectively, and therefore, they are expected to be potential candidates as organic dyes for applications in DSSCs. It is worth noting that PY-4NP and PY-3NP exhibit strong adsorption energy on the surface and interesting PCE values of 11.66% and 8.29%, respectively. This opens up possibilities for their application in DSSCs either as standalone sensitizers or as co-sensitizers alongside metal-free organic dyes or organic–inorganic perovskite solar cells. [ABSTRACT FROM AUTHOR]

The development of photocatalysis is hindered, in part, by the quick recombination of photogenerated carriers and the instability of light sources. In this study, the problem of too-fast electron–hole pair compounding in photocatalysis is effectively regulated by the polarization field of pyroelectric materials using the pyroelectric method. Self-polarized pyroelectric materials that depend on temperature variations can generate usable electrical energy and polarized charge carriers to degrade organic pollutants. Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) is a relaxor ferroelectric material with spontaneous polarization characteristics. The PMN–0.30PT:1 mol%Sm3+ catalyst was prepared by applying the high-temperature solid-state reaction method. Under the dark condition and nine cold–hot cycles of 23 °C–68 °C, using H2O2-assisted PMN–0.30PT:1 mol%Sm3+ as a catalyst, the degradation rate of rhodamine 6G (10 mg L−1) was 94.3 ± 2.5%. In addition, the degradation rates of 88.52% and 64.32% were obtained for rhodamine B (10 mg L−1) and methylene blue (10 mg L−1), respectively. This study provides a new approach to the pyroelectric catalytic degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

In this study, a new cobalt-based metal–organic framework (JLNU-500), [Co2(OH)(PBA)(AIP)]·3DMA·0.75H2O (4-(pyridin-4-yl) benzoic acid (HPBA), 5-aminoisophthalic acid (H2AIP) and N,N-dimethylacetamide (DMA)), was fabricated using a solvothermal method. JLNU-500 has 3D network architecture with 1D nanopore channels. The prepared JLNU-500 can activate peroxymonosulfate (PMS) for Rhodamine B (RhB) dye decolorization. Interestingly, catalyst JLNU-500 exhibited high efficiency for PMS activation, and nearly 100% (above 99.8%) removal of RhB with a high concentration (50.0 mg L−1, 100 mL) was achieved within 6 min. The reaction rate constant of the JLNU-500/PMS system was 1.02 min−1 calculated based on the pseudo-first-order kinetics, which is higher than that of the other reported catalysts. Furthermore, the factors, which could influence PMS activation were also investigated, such as PMS dosage, catalyst dosage, pollutant RhB concentration, reaction temperature and solution pH. More importantly, the radical trapping experiments ferreted out that sulfate (SO4˙−) and hydroxyl (˙OH) radicals were the dominating oxidants in the removal of RhB. Moreover, the possible degradation mechanism was elucidated. This study provides new prospects for fabricating new MOFs that can potentially be employed for high-efficiency catalytic oxidation as heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Hydrothermal synthesis was used to create four different POM-based compounds, namely {[Co(Hptpm)2(β-Mo8O26)0.5(ξ-Mo8O26)0.5]}·H2O (1), [Co(Hptpm)2(δ-Mo8O26)]·H2O (2), [Co(Hptpm)2(β-Mo8O26)] (3) and [Zn(Hptpm)2(β-Mo8O26)] (4) (ptpm = 4-[3-(3-pyridine-2-yl-[1,2,4]triazol-4-yl)-propyl]- morpholine). 1-4 containing different octamolybdate isomers were characterized. Compounds 1-4 showed good electrochemical performance and can be utilized as bifunctional sensors for NO2 -, H2O2, Cr(VI) and Fe(III). Taking compound 1 as an example, the detection limits are 0.081 μM for NO2 -, 0.072 μM for H2O2, 0.054 μM for Cr(VI) and 0.063 μM for Fe(III), respectively. Compounds 1-4 have good capacitance. Moreover, compounds 1-4 also show good adsorption properties for organic cationic dyes. The cationic dyes include methylene blue (MB), crystal violet (CV) and neutral red (NR). In addition, 1-4 have excellent characteristics that can reduce Cr(VI) to Cr(III) by photocatalytic technology. Within 30 min, the reduction rates were 95.85% for 1, 93.99% for 2, 90.29% for 3 and 88.18% for 4. [ABSTRACT FROM AUTHOR]

One-pot co-precipitation of target molecules e.g. organic dyes and the synthesis of a crystal containing microporous–mesoporous regimes of zeolitic imidazolate frameworks-8 (ZIF-8) are reported. The synthesis method can be used for cationic (rhodamine B (RhB), methylene blue (MB)), and anionic (methyl blue (MeB)) dyes. The crystal growth of the ZIF-8 crystals takes place via an intermediate phase of zinc hydroxyl nitrate (Zn5(OH)8(NO3)2) nanosheets that enabled the adsorption of the target molecules i.e., RhB, MB, and MeB into their layers. The dye molecules play a role during crystal formation. The successful encapsulation of the dye molecules was proved via diffuse reflectance spectroscopy (DRS) and electrochemical measurements e.g., cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The materials were investigated for carbon dioxide (CO2) adsorption and adenosine triphosphate (ATP) biosensing. ZIF-8, RhB@ZIF-8, MB@ZIF-8, and MeB@ZIF-8 offered CO2 adsorption capacities of 0.80, 0.84, 0.85, and 0.53 mmol g−1, respectively. The encapsulated cationic molecules improved the adsorption performance compared to anionic molecules inside the crystal. The materials were also tested as a fluorescent probe for ATP biosensing. The simple synthesis procedure offered new materials with tunable surface properties and the potential for multi-functional applications. [ABSTRACT FROM AUTHOR]

There has been rapid development of organic–inorganic perovskite solar cells (PSCs) in recent years, but efficiency and stability challenges remain due to the massive defects in perovskite films. Here, the organic dye Th-azi-Pyr (ethyl 2-(2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene) hydrazineyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate) with carbonyl, pyrazolone structure, and benzene ring was synthesized and used to prepare high-quality perovskite film as an additive. Th-azi-Pyr formed relatively stable intermediate ligands with uncoordinated Pb and I, slowing the crystal growth and reducing the grain boundary defects of perovskite. In addition, the benzene ring in the dye protected against moisture and increased the stability of the perovskite film. Therefore, the Th-azi-Pyr-modified PSC assembled in an air environment exhibited a promising power conversion efficiency (PCE) of 19.27%, which is superior to the 15.33% of the control PSC. Additionally, 88% of the original performance was maintained after 300 h at 25 ± 5 °C and 50 ± 10% relative humidity, implying that the modified PSCs exhibited greater stability than the untreated PSCs. This work indicates that simple and low-cost organic dyes are excellent defect passivators for high-performance PSCs. [ABSTRACT FROM AUTHOR]

How to facilitate photogenerated-carrier separation is an important step in developing excellent semiconductor photocatalysts for environmental pollutant removal. Herein, Ag2MoO4 (AMO) nanoparticles were assembled onto the surface of BiOBr (BOB) nanosheets to construct a highly efficient Z-scheme AMO/BOB heterojunction photocatalyst. Several analytical techniques were used to elucidate the characteristics and photocatalytic mechanism of the AMO/BOB heterojunction. Photodegradation experiments for removing methylene blue under simulated-sunlight irradiation reveal that a 20%AMO/BOB heterojunction exhibits excellent photodegradation activity with η(30 min) = 93.8% and kapp = 0.08638 min−1, which were greater by 4.5 and 5.6 times in comparison with that of pure BOB and AMO, respectively. Based on the experimental and density functional theory (DFT) calculation results, it is proposed that the Z-scheme carrier transfer/separation mechanism dominates the enhanced photodegradation performance of the composite photocatalysts. Additionally, the potential application of AMO/BOB photocatalysts in degrading various organic pollutants (including organic dyes, antibiotics and other serious organic pollutants) was also investigated. [ABSTRACT FROM AUTHOR]

Multiple emission metal–organic frameworks (MOFs) are superior materials for ratiometric fluorescence sensing and visible detection applications. The guest-encapsulation strategy is a simple method for the integration of the open structure of MOFs and the abundant choice of emissive guests. Herein, we reveal the factors that affect the performance of host–guest multi-emission MOFs based on the choice of ligands, metal nodes, and guest dyes. The size of organic dyes is often larger than 1 nm, which is incompatible with the small pores of traditional MOFs. Therefore, we selected a flexible ligand, i.e., 1,3,5-tris(5-methoxy-1,3-benzene dicarboxylic acid)benzene (L), to enlarge the pore size of the MOF to 18 Å. Energy transfer may occur from the ligand and guest dye to the metal nodes; thus, we selected the Gd3+ ion because of its high excited state level. L and Gd3+ ions were used to form the Gd–L MOF with the pore size of 18 Å, as revealed by the single crystal result. Rhodamine B (RhB), as the guest dye with the size of 15.9 × 11.8 × 5.6 Å3, was encapsulated in Gd–L MOF, which was denoted as RhB@MOF. The matched size between RhB and the MOF pore and the breathing effect of the flexible MOF effectively prevented the leakage of RhB. Accordingly, dual emission was observed at 360 nm and 583 nm under the excitation of 290 nm from RhB@MOF. Alternatively, Cu2+ quenched the emission at 360 nm due to the electron transfer process, while Fe3+ interacted with both L and RhB, and thus quenched the two emissions simultaneously. However, other metal ions showed little effect on the two emissions. Consequently, the differentiation between Cu2+ and Fe3+ as well as them from other metal ions was realized with the dual-emission MOF. Thus, the guest-encapsulation strategy is simple and flexible ligands are efficient to encapsulate molecular dyes for dual-emission MOFs to improve their sensing performance, while flexible ligands are powerful to enhance the capacity and extend the applications of MOFs. [ABSTRACT FROM AUTHOR]

Nano-ferroelectric materials have excellent piezoelectric performance and can degrade organic dye by ultrasonic vibration in an aqueous solution. Here, BaTiO3 (BT) nanoparticles were prepared by a sol–gel/hydrothermal method and further applied in dye degradation in wastewater. BT nanoparticles exhibited excellent catalytic performance for organic dye molecule degradation through the piezo–Fenton synergistic effect. It was found that both the degradation efficiency and reaction rate were boosted by the increase of the molecular weight of organic dyes. The degradation efficiency toward different organic dyes exhibited a trend of CR > ABK > TH > RhB > MB > MO. For example, a high piezo–Fenton-catalytic degradation ratio of 82.8% at 5 min and 0.337 min−1 rate constant were achieved for the CR dye solution (10 mg L−1), which were 3.2 and 6.4 times the corresponding values of piezo-catalytic only degradation. These results mainly originate from the intrinsic properties of BT nanoparticles that can enhance the separation of charge and promote the formation of hydrogen peroxide (H2O2) and hydroxyl radicals (·OH) under ultrasonic vibration. Furthermore, the reaction of Fe(II) with H2O2 can further enhance the formation of ·OH, which can accelerate the degradation of organic dyes. These results indicate that the piezo–Fenton synergistic effect may provide a new clue for the development of the wastewater treatment field under mechanical vibration. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have recently emerged as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate hierarchical porous-carbon-related nanostructured functional materials. In this work, we used Cu(II) ions and aromatic dicarboxylic acid to construct [Cu3(4,4′-oba)2(μ2-OH)2(H2O)2]n (4,4′-H2oba = 4,4′-oxybisbenzoic acid) as a precursor for the preparation of carbon nanostructures. Doping foreign elements into intrinsic MOF-based nanomaterials is an effective way to enhance the adsorption property and photocatalytic activity; thus, we designed a facile method to synthesize a vanadium-doped mixture of Cu2O and Cu nanoparticles encapsulated in a Cu-MOF-derived carbon nanostructure (C-V-1) in this work for the first time. Benefiting from the protection of the carbon shell and regulation of the electronic structure by doping vanadium and phase-mixing Cu2O and Cu, the adsorption capacities of C-V-1 for MB, RhB, MO, CR and GV at room temperature are 174.13, 147.06, 179.92, 275.90 and 611.81 mg g−1 in 240 min, respectively, while the photocatalytic degradation rates are 88.14% for MB, 79.80% for RhB, 71.31% for MO, and 71.19% for CR after 4 h. In addition, the degradation rate is larger than 99.01% for GV after only 30 min of UV irradiation. This strategy of using a diverse MOF as a structural and compositional material to create a multifunctional composite/hybrid may expand the opportunities to explore highly efficient, fast and robust adsorbents and photocatalysts for water treatment. [ABSTRACT FROM AUTHOR]

Anionic metal–organic frameworks (MOFs) are beginning to have a great impact in the field of absorption and separation of ionic organic molecules due to the enhanced electrostatic interactions between their anionic frameworks and counter-ionic guests. Herein, the rational design and synthesis of two mesoporous anionic MOFs, [Zn3(ITTC)3](Me2 NH2)3·3DMF·H2O (1) and [Cd2(ITTC)3](Me2NH2)5·2DMF (2), where H3ITTC = 4,4′,4′′-(1H-imidazole-2,4,5-triyl) tribenzoic acid, is reported. Structural analysis revealed that both materials are anionic MOFs with a 2-fold interpenetrating three dimensional (3D) framework. The cross sectional area of the open one-dimensional rectangular channels is 31.7 Å × 15.6 Å for 1, of which the architecture is indicative of an unprecedented (3,3,4,5)-connection topology. For 2, the diameter of the open one-dimensional regular hexagonal channel is about 34.1 Å, decorated with uncoordinated carboxyl O atoms, and the framework exhibits a (3,4)-connected fcu network. Due to their anionic frameworks and bulky pore window sizes, both MOFs can be employed for absorbing and separating the cationic organic dye methylene blue (MB). The results reveal that both MOFs have better dye adsorption selectivity for MB, than for MO and SDI, because of charge and size-matching effects, enabling them to be potential candidates for use in environmental cleaning. By comparison, 2 presents superior selectivity and adsorptivity for cationic MB which depends on the presence of a basic functionalized pore surface. [ABSTRACT FROM AUTHOR]

Three new coordination polymers (CPs) based on Cu(II), namely {[Cu6(H2L)4(4,4′-bpy)6(H2O)2]·16H2O}n(1), {[Cu(H3L)(1,4-bib)]·3H2O}n(2), and {[Cu2(H2L)2(1,4-bib)2][Cu(1,4-bib)(H2O)2]}n·4nH2O(3) (H5L = 6-(3′,4′-dicarboxyphenoxy)-2,3,5-benzene tricarboxylic acid, 4,4′-bpy = 4,4′-bipyridine and 1,4-bib = 1,4-bis(1H-imidazol-1-yl)benzene) were synthesized under hydrothermal conditions and characterized. 1 adopts a three-dimensional structure and can be described with the point symbol {4·52}2{42·54·64·83·92}{5·104·12} whereas 2 shows a layered structure. 3 can be perceived as a complex salt of two coordination polymers: the cationic component [Cu(1,4-bib)(H2O)2]n2+ (3a) represents a chain polymer and the second anionic moiety [Cu2(H2L)2(1,4-bib)2]n2− (3b) corresponds to a 2D sub-structure. In the presence of H2O2, all complexes 1–3 act as efficient photocatalysts for the degradation of the dye methylene blue (MB). The effects of properties such as initial MB concentration, catalyst dosage, pH value, and H2O2 concentration on MB degradation were also investigated and analyzed in detail. Compounds 1–3 exhibit excellent structural stability during the catalytic process and can be reused at least three times. The hydroxyl radical (OH˙) and holes (h+) were confirmed as the main active species in the degradation process. [ABSTRACT FROM AUTHOR]

Water pollution originating from organic dyes is endangering the survival and development of society; however, adsorbents with high capacity (>5000 mg g−1) for the fast removal (≤30 min) of Congo Red (CR) in aqueous solution have been not reported to date. In the present work, an acid–base stably layered MOF, [Cd(H2L)(BS)2]n·2nH2O (L-MOF-1, H2L = N1,N2-bis(pyridin-3-ylmethyl)ethane-1,2-diamine, BS = benzenesulfonate), was hydrothermally prepared. L-MOF-1 exhibited high-performance adsorption of CR in aqueous solution at room temperature. The experimental adsorption capacity of the L-MOF-1 adsorbent towards CR reached up to about 12 000 mg g−1 in 20 min in the pH range of 2.2–4.7, which is the best adsorbent with the highest capacity and fastest adsorption of CR to date. The spontaneous adsorption process can be described by the pseudo-second-order kinetic and Langmuir isotherm models. Meanwhile, the L-MOF-1 absorbent possessed a highly positive zeta potential in acid condition (even at pH = 2.2, zeta potential = 36.2 mV). Its good adsorption performance mainly originates from its strong electrostatic attraction with CR in acidic condition, together with diverse hydrogen bonds and π⋯π stacking interactions. Furthermore, the L-MOF-1 absorbent exhibited good selectivity and could be reused five times through simply washing, where its adsorption efficiency was hardly affected. Therefore, L-MOF-1 is a potential absorbent for effectively removing CR from dye wastewater. [ABSTRACT FROM AUTHOR]

Decontamination of industrial wastewater containing toxic organic dye molecules and oxoanions is urgently desirable for environmental sustainability and human health. Water-stable porous metal–organic frameworks (MOFs) have emerged as highly efficient photocatalysts and/or adsorbents for water purification through controllable integration of the constitutive requirements. To reveal the inclusion anion effect of microporous MOFs on wastewater treatment, two isostructural MOFs incorporating positive charge and semiconductive characteristics, {[Cu(tpt)]·3H2O·0.5SO4}n (1) and {[Cu(tpt)]·2H2O·ClO4}n (2, tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine), have been synthesized and employed as dual-functional materials for both dye photodegradation and oxoanion removal. The two MOFs possess the same 3-fold interpenetrating cationic backbones but are encapsulated by highly disordered sulfate or perchlorate in the open channels. These included anions have significantly tuned the hydrophilicity of the channels, extended the visible-light absorption, optimized the bandgap and decreased the conduction band potential. Under the low-energy irradiation of a 30 W LED lamp, MOF 1 has selectively and efficiently degraded rhodamine B compared to 2 with accelerated kinetics, resulting from the stronger reduction ability and less migration resistance of the photogenerated electrons. Instead, MOF 2 can quickly capture harmful MnO4− and Cr2O72− by exchanging with the entrapped ClO4−, with maximum adsorption amounts of 557 and 168 mg g−1, respectively, under ambient conditions. The improved decolorization of the aqueous solution over 2 benefits essentially from the shape and charge memory effect and the smaller hydration energy of ClO4− than SO42−. These interesting observations highlight the importance of the included anions inside the porous MOF semiconductors on wastewater treatment. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have recently emerged as a new type of prospective photocatalytic material due to their characteristics such as tunable structures, pore modification, crystalline nature with eliminated structural defects, unique semiconductor properties, etc. However, most of these systems also suffer from low activity, high cost, and low visible light utilization. Xanthene dyes are eco-friendly organic dyes used in photocatalysis. They possess the advantages of low cost, low toxicity, and high visible light response; so, they can be directly used as building blocks to fabricate MOF materials or as proper cocatalysts to increase the absorbance of irradiation leading to the construction of a reasonable photocatalytic system. Herein, we have summarized the recent developments in the study of MOFs containing xanthene dyes for photocatalytic applications. The paper can be divided into two sections depending on whether the xanthene dyes are coordinated in the MOF structure: (i) MOFs synergized with xanthene dyes for photocatalytic applications and (ii) MOFs with xanthene dyes incorporated within ligand backbones for photocatalytic applications. Moreover, in this paper, the present challenges and future opportunities in this field are also discussed. [ABSTRACT FROM AUTHOR]

In this report, metal organic frameworks (MOFs) are designed and tuned for structural variations in order to induce metal capture which in turn directs dye adsorption properties. The three MOFs, Cu-MOF-2COOH, Ni-MOF-COOH and Cd-MOF, are synthesized by employing 1,3,5-benzenetricarboxylic acid (H3-BTC) as the main ligand and 4,4′-dipyridyl (bipy) as the spacer. The MOFs have been characterized using various spectral techniques and single crystal X-Ray studies. A topological analysis using TOPOS Pro reveals that the MOFs possess varying topologies i.e.hcb, hxl, sql and 2C1. Cu-MOF-2COOH and Ni-MOF-COOH contain two and three uncoordinated carboxylic acid groups, respectively, and in Cd-MOF, all three –COOH groups are utilized in bonding. The dye adsorption properties of the MOFs with free carboxylate group(s) were checked and we found that both MOFs are unable to adsorb any of the dyes significantly. The free carboxylate group(s) in the MOFs inspire us to elaborate their metal capturing properties. In different solvents we checked the metal capturing properties of Cu-MOF-2COOH and Ni-MOF-COOH with different metal salts. Surprisingly, both MOFs show better metal capturing properties towards the hard and highly polarizing Fe3+ ion in aqueous medium. Theoretical studies show that the free carboxylate(s) are involved in binding with metals. The post synthetically modified materials (Fe@Cu-MOF-2COOH and Fe@Ni-MOF-COOH) were further checked for their dye adsorption properties and both the doped MOFs show better adsorption properties towards the MB and MO. Furthermore, three kinetic models were employed to understand the reaction mechanism of adsorption and the pseudo second order kinetic model fits the best in both cases. The uncoordinated carboxylate groups in the channels act as post synthetic modification sites for metal capture and the post synthetically modified material thus formed attracts organic dyes following the HSAB concept. The strong interaction existing between the hard Fe3+ ion and hard donors of the dyes is responsible for the enhanced adsorption. [ABSTRACT FROM AUTHOR]

Dye photodegradation is an important research topic, and great efforts have been made to target the photocatalysts with highly efficient and selective performance. Reported here are two layered anion chalcogenide frameworks with semiconducting properties combined with highly open interlayer spaces, which are used as efficient photocatalysts to show excellent size and charge selectivity towards organic dye molecules. In addition, the organic templates inside the chalcogenide frameworks are exchanged via an ion-exchange process, and the resulting host frameworks with much looser internal spaces play significant roles in improving the photocatalytic activity. [ABSTRACT FROM AUTHOR]

As environmental pollution and energy shortages have become global concerns, the construction of highly efficient catalysts using facile and green methods remains a long-term goal. In the present study, we proposed a facile catalyst preparation method in which Ag/TiO2 composites were coated on the surface of the porous pure inorganic crystalline vanadium phosphates (VPO) by a one-step strategy. More importantly, the in situ reduction of Ag nanoparticles was achieved at room temperature without severe conditions or hydrogen atmosphere in which the porous VPO was employed as the reductant. The prepared Ag/VPO@TiO2 composites act as a class of efficient bifunctional catalysts for visible light photodegradation of MB molecules and catalytic reduction of p-nitrophenol (4-NP). Among these samples, the 6.82%Ag/VPO@TiO2 composite exhibited a superior photocatalytic activity in the degradation of MB and an ultrafast reduction rate for 4-NP of about 0.1 mM/40 s. The photocatalytic mechanistic studies revealed that the encapsulated VPO with a narrow band gap not only efficiently enhances the photosensitivity of the TiO2 but also largely facilitates the photogenerated charge separation. The subsequent deposition of Ag NPs is able to further promote electron transfer ability, which leads to the higher photocatalytic activity. Moreover, the contact of Ag NPs with the surface of semiconductor TiO2 can result in an electron-enhanced area in their interface that could effectively facilitate the uptake of electrons by the 4-NP molecules and then improve the reduction activity. [ABSTRACT FROM AUTHOR]

A family of diimine (N^N) and cyclometalating (N^C) ligands based on a phenanthro-imidazole aromatic system: 2-pyridyl-1H-phenanthro[9,10-d]imidazole (N^N); 2-R-1-phenyl-1H-phenanthro[9,10-d]imidazole, R = phenyl (N^C4), 3-iodophenyl (N^C5) and 4-nitrophenyl (N^C6) were prepared. It was found that N^C4 and N^C5 show π–π* fluorescence typical of aromatic systems of this sort, whereas the donor–acceptor architecture of N^C6 leads to strong emission solvatochromism and acidochromism, indicating the charge transfer character of the fluorescence observed. Six iridium(III) complexes (1–6) [Ir(N^C#)2(N^N)]+, where # = 1–6 and N^C1 = 2-phenylpyridine, N^C2 = 2-(benzo[b]thiophen-2-yl)pyridine, and N^C3 = methyl 2-phenylquinoline-4-carboxylate, were also synthesized and characterized. The complexes obtained display moderate to bright phosphorescence with quantum yields up to 46% in degassed solution. The photophysical characteristics of 1–6 were studied in detail. DFT and TD DFT calculations were used for the assignment of electronic transitions responsible for the absorption and emission of these compounds. The variations in the cyclometalating ligand structure give rise to rich photophysics of the complexes obtained. It was found that the orbitals of both N^C and N^N ligands make a major contribution to the formation of emissive excited states and a delicate balance between the energy of the ligands' frontier orbitals determines the emission character. [ABSTRACT FROM AUTHOR]

Narrow band red emitting phosphors play a vital role in high performance smart white LEDs. In this context, a series of new Eu(III) complexes have been synthesized with neutral ligands (C1-functionalised phenanthro-imidazole-based ancillary ligands substituted with phenyl moieties (m-CF3, p-CF3, p-CH3 and 1-naphthyl and 2-naphthyl group)) and dibenzoylmethane (DBM) as an anionic ligand. All the newly synthesized Eu-complexes showed extremely narrow band red emission due to the electric dipole transition (5D0–7F2, both in solid and thin film) with high quantum efficiency. A combined experimental and theoretical study indicates that the energy transfer from the ligand to the metal ion is complete. A temperature dependent photoluminescence (PL) study in solution reveals that the red emission is retained (only the ED (5D0–7F2) intensity decreases with increasing temperature). Red LEDs and hybrid white LEDs were fabricated by using a near UV LED chip with europium complexes and a near UV/blue LED conjugated with a yellow organic dye and europium complex mixture, respectively. Hybrid white LEDs (Eu(DBM)3Phen-pCN-pCF3 + yellow organic dye) showed superior CRI (84%) and CIE (x = 0.36, y = 0.39) values (near UV based) and CRI (82%) and CIE (x = 0.34, y = 0.36) values (blue LED based). In addition, the studied Eu-complexes herein showed excellent reversible on–off–on luminescence behavior with exposure to acid–base vapours. Detailed spectroscopic investigation reveals that the protonation of the Eu-complexes (ligands) plays a key role in the on–off–on luminescence. [ABSTRACT FROM AUTHOR]

Using chalcone dicarboxylic acid ligands, three different metal–organic frameworks have been successfully obtained. Interestingly, structural diversity has been observed. The difference between compounds 2 and 3 is the inconsistent orientation of the adjacent binuclear Cd clusters. In addition, the photocatalytic properties of compounds 1 and 2 for the degradation of several organic dyes have been explored. [ABSTRACT FROM AUTHOR]

Nano-scale MOF composite materials prepared by combining inorganic semiconductors with controllable pore structures and functional active sites for the effective removal of organic dyes will exhibit more excellent adsorption activity. In this paper, MIL-101(Cr) was used as a carrier and two-step hydrothermal methods were successfully used to prepare flower-like TiO2/MIL-101(Cr) composite nano-adsorbents with different sizes. The results of XRD, SEM, XPS and other characterization methods showed that when the molar ratio of Ti : Cr was 0.2 : 1, the composite nano-adsorbent exhibited better adsorption performance and removal efficiency for methyl orange (MO) in aqueous solution. By assembling TiO2 on MIL-101(Cr), Ti replaced part of Cr, and the positively-charged TiO2/MIL-101(Cr) nanocomposite and negatively-charged MO in aqueous solution formed a strong interaction force. In addition, the π–π packing interactions of the benzene ring of MIL-101(Cr) and the electrostatic force between TiO2 and MIL-101(Cr) also enhanced the performance and adsorption efficiency of the adsorbent to a certain extent. The BET results showed that the large specific surface area and average pore diameter of the TiO2/MIL-101(Cr) nanocomposites effectively improved the adsorption performance of the composites. The results showed that the MO removal efficiency of 20% TiO2/MIL-101(Cr) can reach 93.03% at 80 min. But when 20% TiO2/MIL-101(Cr) was used to adsorb 70 mg·L−1 MO, the experimental maximum adsorption capacity was 242.02 mg·g−1. [ABSTRACT FROM AUTHOR]

The design and development of an environmentally benign porous adsorbent for effective simultaneous adsorption of organic dyes and heavy metals from water are important but remain a big challenge. Herein, we have designed a layered double hydroxide/metal–organic framework-based hierarchical nanocomposite (LDH/MOF HNC) by a facile, room-temperature in situ approach. This paper for the first time reports a hierarchical trimodal micro-meso-macroporous LDH/MOF composite with a high surface area (surface area 1282 m2 g−1 and pore volume 0.93 cm3 g−1), synthesised by uniformly growing MOF nanocrystals on the surface of LDH nanosheet ultrathin films. An attempt is made to quantitatively demonstrate the adsorption data via suitable nonlinear kinetic and isotherm equations for single, simultaneous, and consecutive adsorption of the orange II reactive dye and Cr(VI). Experiments were performed at various values of pH (6.0–11.0), adsorbent dosages (1.0–8.0 mg), adsorbate concentrations (5–500 mg L−1), and temperatures (293–323 K). The Langmuir model revealed a satisfactory fit to the equilibrium data of the LDH/MOF HNC (correlation coefficients R2 > 0.98) with a calculated maximum adsorption capacity of 1173 and 733 mg g−1 for orange II and Cr(VI), respectively, in a simultaneous adsorption system. The results of the study demonstrated that LDH/MOF HNCs could potentially be applied as a promising nanoadsorbent for the simultaneous removal and extraction of toxic dyes and metals from water. [ABSTRACT FROM AUTHOR]

Six new Anderson-type polyoxometalate (POM)-based metal–organic complexes (MOCs), namely, {HCu(HPCAP)2[CrMo6(OH)6O18]}·2H2O (1), {Zn4(PCAP)2[CrMo6(OH)6O18]2(H2O)12}·4H2O (2), {Zn3(PCAP)2[CrMo6(OH)5O19](H2O)6}·6H2O (3), {Ni3(PCAP)2[NiMo6(OH)5O19](H2O)6}·8H2O (4), {Cu3(PCAP)2[AlMo6(OH)5O19](H2O)6}·6H2O (5), and {Co3(HPCAP)2[AlMo6(OH)6O18](H2O)10}[AlMo6(OH)6O18]·6H2O (6) (HPCAP = 3-(2-pyridinecarboxylic acid amido)pyridine), were constructed from diverse metal ions (CuII/ZnII/NiII/CoII), the HPCAP ligand and various Anderson-type POM anions under hydrothermal and solvothermal conditions and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Crystal analysis shows that complex 1 has a 3D supramolecular structure based on the CrMo6 anions and the 1D metal–organic ribbon chains [Cu(HPCAP)2] via hydrogen bonds. Complex 2 is a 2D supramolecular layer composed of two kinds of dinuclear metal clusters of [Zn2(CrMo6)2] and [Zn2(PCAP)2]. Complexes 3–5 show similar 3D frameworks. In 3–5, [M1Mo6]3− (M1 = Cr for 3, Ni for 4, and Al for 5) anions are bridged by MII ions (M = Zn for 3, Ni for 4, and Cu for 5) to give a 1D M–M1Mo6 inorganic chain; the adjacent 1D inorganic chains are connected through two directions of [M2(PACP)2] rings to form a 3D framework. It should be noted that in complex 4, the NiMo6 anions are in situ generated from the NiII ion and Mo7O246− anions, which is rarely observed in POM-based MOCs. Complex 6 shows a 1D ladder-like supramolecular double chain, which is composed of 1D Co–AlMo6 inorganic chains, [Co2(HPCAP)2] dual-core rings and discrete AlMo6 polyanions interlinked by hydrogen bonding interactions. These structural diversities show that solvents play key roles in the construction of various architectures. All of the title complexes have excellent adsorption activities for the cationic dyes methylene blue (MB) and gentian violet (GV); in particular, complex 5 is capable of selectively adsorbing MB and GV from the mixtures of MB and MO and GV and MO, respectively. In addition, the electrochemical properties of complexes 1, 4, and 5 are also studied. [ABSTRACT FROM AUTHOR]

A novel 2D zinc(II) metal–organic framework, formulated as [Zn(L)(H2O)]·H2O (1) (H2L = 4-(pyridine-4-yl) phthalic acid), has been successfully obtained under solvothermal conditions. This metal–organic framework (MOF) material exhibits efficient photocatalytic activity towards the degradation of organic dyes in the absence of any photosensitizer or cocatalyst. Its catalytic performance for rhodamine B (RhB) and methyl orange (MO) degradation was superior to most reported MOFs with a degradation efficiency of 98.5% for RhB and 83.8% for MO within 120 min in the absence of H2O2, which could be attributed to its high efficiency in generating ·O2− (an effective oxidant for the degradation of dyes). The possible mechanism of the reaction was discussed in detail. In addition, 1 shows stable catalytic efficiency after five reaction cycles, which indicates that 1 exhibits efficient catalytic activity and good reusability toward the degradation of organic dyes, enabling it to be a potential candidate for environmental governance. [ABSTRACT FROM AUTHOR]

Silver doped TiO2 (Ag–TiO2) materials show high activity and good stability in photocatalysis, but the mechanism could not be illustrated clearly due to their imprecise and inhomogeneous characteristics. Ag-doped titanium-oxo clusters (Ag-TOCs) with an exact crystal structure, which are rarely reported, are beneficial for further understanding structure–property relationships. Herein, six new Ag-TOCs with a butterfly-like Ti8Ag2 core have been synthesized through facile solvothermal reactions, in which two Ag ions are successfully linked to the surface of the Ti8 core. Of interest, the Ti6 unit of the Ti8Ag2 core is similar to that found in the anatase structure and may be a promising model for Ag–TiO2 materials. The band gaps of these Ag-TOCs show different values mainly affected by different ligands. DFT calculations revealed that the lowest energy bands of Ag-TOCs are attributed to the Ag-to-TiO core charge transfer bands. Additionally, all Ag-TOCs exhibit good photoelectric response and high photodegradation activity towards organic dyes. [ABSTRACT FROM AUTHOR]

A new pentadentate quinoline–pyridine ligand and its iron (1), cobalt (2) and nickel (3) complexes have been synthesized and characterized. The iron complex exhibits excellent photocatalytic activity towards CO2-to-CO conversion with a TON(CO) of 544 and a selectivity of 99.3% using the commercially available organic dye purpurin as the photosensitiser and BIH as the electron donor. In contrast, the cobalt and nickel complexes result in very low activity for CO production with a TON of only 8 and 15, respectively. On the other hand, all the three complexes show good electrocatalytic activity for CO2 reduction when using 2,2,2-trifluoroethanol as the proton source with the active intermediate of M0 species. The lack of activity in photocatalytic CO2 reduction by 2 and 3 can be attributed to the redox potential of MI/M0 which is significantly more negative than that of PP−/PP2− while in the case of 1 the FeI/Fe0 redox potential becomes more positive than that of the PP−/PP2− couple. [ABSTRACT FROM AUTHOR]

Herein, an anionic indium–organic framework, FJI-H21, was successfully prepared using an azobenzene-derivated tetra-carboxylate ligand, which had well-shaped honeycomb-like hexagonal channels along the crystallographic b-axis and trapezoidal window-like one-dimensional channels along the crystallographic c-axis. Due to its intrinsic microporosity, FJI-H21 demonstrated highly selective storage of C2–C3 hydrocarbons over CH4 under ambient conditions; furthermore, the selectivities for equimolar light hydrocarbons/CH4, estimated by the ideal adsorbed solution theory (IAST), indicated that FJI-H21 could efficiently separate C2–C3 hydrocarbons from CH4. However, FJI-H21 could also selectively adsorb cationic dyes, such as methylene blue (MB), ethyl violet (EV) and cation red (GTL) from anionic or neutral dyes with high uptake, rapid adsorption rate, and good recyclability; especially, using microcrystalline materials developed by fast synthesis, the adsorption rate for cationic dyes was significantly improved by 100-fold as compared to that of block crystals. The abovementioned results indicate that the sizes of the samples have an important influence on their adsorption performance. [ABSTRACT FROM AUTHOR]

Chalcogenolate clusters Cd6Ag4(EPh)16(DMF)3(CH3OH) (E = S, Se) with supertetrahedral structures are isolated. Further interlinking the clusters with organic linker 4,4′-trimethylenedipiperidine in the stepwise assembly approach forms two-dimensional coordination polymers. The clusters and the coordination polymers show tunable band gaps and efficient photocatalytic activities for the degradation of aqueous dye solution. This study demonstrates the great potential of using chalcogenolate clusters and their coordination polymers in photocatalysis applications. [ABSTRACT FROM AUTHOR]

Uranium is unique owing not only to its intriguing physiochemical properties, but also to the diverse coordination chemistry that uranyl adopts and bonding that enables rich and unpredictable topologies of uranium-bearing materials. Six anionic uranium oxyfluorides with various dimensionalities, including a 3D framework (MeUF), four 2D lamellar structures (EtUF-1, PrUF, BuUF-1, and BuUF-2), and a 1D chained topology (EtUF-2), have been rationally constructed by employing tetra-alkyl ammonium ions as structure-directing agents. By combining the tunable interlayer distance of the lamellar structures with the photooxygenation properties of uranyl ions, a bifunctional platform for highly selective ion-exchange and photocatalytic degradation over organic dyes has been developed. Specifically, BuUF-2 can efficiently capture 94.5% methylene blue (MB+) within 24 h from solution with remarkable selectivity related to both the size and the charge of organic dyes. Such size- and charge-dependent selectivity toward organic dyes has been documented for MOFs, but is rare for 2D lamellar materials. Furthermore, the removal of MB+ can be largely accelerated under UV radiation (e.g. 84.7% for BuUF-2 within 1 h) due to the photocatalytic activities of EtUF-1, EtUF-2, PrUF, and BuUF-2. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of Ce(iii)-doped UiO-66 nanocrystals, revealing their potential to efficiently remove organic dyes such as methylene blue (MB), methyl orange (MO), Congo red (CR), and acid chrome blue K (AC) from aqueous solutions. Specifically, the room-temperature adsorption capacities of Ce(iii)-doped UiO-66 equaled 145.3 (MB), 639.6 (MO), and 826.7 (CR) mg g−1, exceeding those reported for pristine UiO-66 by 490, 270, and 70%, respectively. The above behavior was rationalized based on zeta potential and adsorption isotherm investigations, which revealed that Ce(iii) doping increases the number of adsorption sites and promotes π–π interactions between the adsorbent and the adsorbate, thus improving the adsorption capacity for cationic and anionic dyes and overriding the effect of electrostatic interactions. The obtained results shed light on the mechanism of organic dye adsorption on metal–organic frameworks, additionally revealing that the synergetic interplay of electrostatic, π–π, and hydrophobic interactions results in the operation of two distinct adsorption regimes depending on adsorbate concentration. [ABSTRACT FROM AUTHOR]

Enantiopure ligands, namely (R,R)- and (S,S)-2,2′-(1,4-phenylene) bis(4,5-dihydrothiazole-4-carboxylic acid) (H2LRR, and H2LSS) were synthesized, and homochiral metallocyclic rings {Ni6LRR6(H2O)12} (1RR) and {Ni6LSS6(H2O)12} (1SS) were obtained and their structures were determined. The complexes exhibit excellent activity for the photocatalytic degradation of organic dyes. [ABSTRACT FROM AUTHOR]

Dye capture and separation through coordination polymers (CPs) has been a promising research field in recent times due to the toxic and nondegradable nature of organic dyes released into the environment from various industries as well as the reusability of CPs for the said purpose. Here, we report the synthesis and characterization of two mixed ligand CPs {[Zn2(HBTC)2(L)(H2O)2](C2H5OH)3}n (CP1) and {[Zn5(BTC)2(L)3(OH)4(H2O)2](H2O)4(CH3OH)11}n (CP2) (where H3BTC = 1,3,5-benzene tricarboxylic acid and L = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) by the stoichiometric variation of the precursors. The crystal structure analysis revealed that CP1 is a 2D network composed of a [Zn2(HBTC)2(H2O)2]n motif linked via terminal nitrogen atoms of L and CP2 is a 3D framework in which symmetrically disposed two-dimensional {[Zn5(BTC)2(L)3(OH)4(H2O)2]}n sheets composed of pentanuclear [Zn5(RCO2)6(μ3-OH)2(μ2-OH)2(H2O)2] SBUs are pillared by L ligands. Adsorption and separation of cationic dyes by CP1 and the solid-state fluorescence properties of both CPs have been investigated. Cationic dyes (RhB, MB, and MV) can be effectively adsorbed by CP1 from their aqueous solution (61%, 90%, and 97%, respectively) while the anionic dye methyl orange (MO) remains uncaptured. Dye desorption studies and CP1 as a column chromatographic filler for the separation of cationic dyes in water have also been demonstrated. [ABSTRACT FROM AUTHOR]

Two porphyrin chromophores, P1 and P2, were prepared and used as antenna units to coordinate with a metal-free organic dye, JH1, containing pyridine groups. This supramolecular self-assembly strategy can not only effectively improve the light-harvesting ability of the devices but also effectively reduces electron recombination by preventing I3− of the electrolyte from penetrating into the TiO2 surface. The DSSC based on JH1 showed a PCE of 2.46%, with a Voc of 615 mV, Jsc of 6.54 mA cm−2, and FF of 61.18%. After supramolecular self-assembly, the Jsc and Voc of the device were greatly improved. Specifically for the device based on JH1 + P2, the PCE reached 4.39%, which is about 78% greater than the PCE of the device based on JH1; this is mainly due to the Jsc increase of 2.85 mA cm−2 and the Voc increase of 93 mV. Compared to co-sensitization, supramolecular self-assembly does not require tedious optimization steps; thus, this may be a promising and convenient way to improve the overall performance of DSSCs. [ABSTRACT FROM AUTHOR]

Ceria–titania doped highly ordered hexagonal and cubic mesoporous silica composite samples with varying amounts of Ce and Ti have been synthesized using hexadecyltrimethylammonium bromide (CTAB) surfactant as a template under basic conditions in the presence of ammonia. The removal of the template resulted in the formation of mesoporous composites doped with Ce and Ti, which were thoroughly characterized via small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXRD), N2 adsorption, scanning and transmission electron microscopy analysis with energy-dispersive spectrometry mapping (SEM-TEM-EDS), inductively coupled plasma atomic emission spectrophotometry (ICP-AES), and ultraviolet-visible diffuse reflectance spectrometry (UV-visible). The electronic states of Ti and Ce species present on the surface of silica were also investigated by X-ray photoelectron spectroscopy (XPS). The catalytic activity of these Ti-modified ceria–silica samples for the photodecomposition of rhodamine B under visible-light irradiation was investigated. The results revealed that a sample with a higher Ti content, as well as equal amounts of Ce and Ti, displayed higher catalytic activity for the photodegradation of the organic dye rhodamine B. [ABSTRACT FROM AUTHOR]

It is of great significance to sense cysteine (Cys) in a simple and fast way because of its potential applications in biological processes. In this contribution, we proposed a Cu2+-mediated fluorescence switchable strategy to detect Cys by designing a dual-signal fluorescence-enhanced sensor. Two organic dyes immobilized onto layered double hydroxides (LDHs) as novel sensors have been fabricated. It was found that the two fluorescence emissions of the obtained ultrathin films (donated as calcein@NFR/LDHs UTFs) could be effectively quenched by Cu2+ (off state), then reversibly recovered by Cys (on state) owing to the specific coordination of Cys and Cu2+. Under the optimal conditions, there were good linear relationships between the off–on efficiency (off–on) and the amount of Cys in the range of 1.0 × 10−7–1.2 × 10−6 M, with lower detection limits of 5.0 × 10−8 M at 520 nm and 2.3 × 10−8 M at 607 nm, respectively. There is little interference by common ions, amino acids and some excipients. The dual-signal fluorescence-enhanced response of the sensor contributes to its high sensitivity and selectivity. The proposed strategy is label-free, fast and selective, which is applicable to the analysis of Cys in medicine with satisfactory results. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework, [(CH3)2NH2]2[Cu3O(SO4)3Cu2L2(DMF)(H2O)]·9DMF (JLU-Liu39) H2L = pyridine-3,5-bis(phenyl-4-carboxylic acid), has been successfully synthesized under solvothermal conditions. Structure analysis indicates that the framework of JLU-Liu39 is constructed by ternary building units which include a rare hexa-nuclear [Cu6O2(SO4)6] cluster, a classical [Cu2(CO2)4] paddlewheel, and a 3-connected hetero-N, O donor ligand. The whole 3D framework possesses a (3,4,4)-connected fjh topology and a large window size of 25.3 Å with high solvent-accessible volume accounting for approximately 75.8% of the cell volume. On the basis of the anionic framework and large pore volume, JLU-Liu39 can efficiently adsorb cationic dyes such as MLB, MV, RhB and neutral dye NR but exclude anionic dyes such as MO and Orange II. Moreover, JLU-Liu39 also exhibits size-exclusion performance for dyes of different sizes, and the dye adsorption amounts decrease with the increase of dye size. With respect to the proportional mixture dyes with different charges for MO & MLB and Orange II & MLB, JLU-Liu39 can be able to selectively adsorb the cationic dye MLB efficiently. Based on the aforementioned considerations, JLU-Liu39 is a good anionic-skeleton MOF material for the adsorption and separation of organic dyes. [ABSTRACT FROM AUTHOR]

The hydrothermal reactions of 1,2,4,5-cyclohexanetetracarboxylic acid (H4L) with CoCl2·2H2O and rigid or semi-rigid bis(imidazole) ligands were able to generate two Co(ii) coordination polymers (CPs), {[Co5(L)2(1,4-bimb)(μ3-OH)2(H2O)8]·2H2O}n (1), {[Co(L)0.5(1,4-bib)]·H2O}n (2) (1,4-bimb = 1,4-bis(imidazol-1-ylmethyl)benzene, 1,4-bib = 1,4-bis(1H-imidazol-1-yl)benzene). CPs 1 and 2 were structurally characterized by elemental analysis, IR spectroscopy, X-ray powder diffraction and single crystal X-ray diffraction. CP 1 features a 3D 3,3,4,4,5-connected framework with an unprecedented {42·8·102·12}{43·6·86}2{43}2{46}2{62·8}2 topology, which represents the first example of CPs with such a topology. CP 2 possesses a three-fold interpenetration 3D framework with mog topology. The distinct structures of the two CPs may result from diverse coordination modes of the (L)4− ligands and different structural characteristics of rigid or semi-rigid N-donor ligands. The thermal stabilities, photoluminescence properties and electrochemical behavior in the solid state for CPs 1 and 2 have been investigated. The photophysical studies indicated that CPs 1 and 2 are potential semiconductive materials. Moreover, both CPs 1 and 2 show high photocatalytic efficiency for the degradation of methylene blue (MB) under UV light irradiation and exhibit good stability and recyclability. A possible photocatalytic mechanism is speculated by introducing t-butyl alcohol (TBA) as a widely used ṖOH scavenger. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are considered as suitable materials for various applications in the area of photocatalysis. On the other hand, 2D BiOBr materials are efficient for the photodegradation of organic dyes under visible light illumination. In this work, BiOBr/NH2-MIL-125(Ti) composite photocatalysts with different NH2-MIL-125(Ti) content were prepared by incorporating NH2-MIL-125(Ti) with BiOBr using a co-precipitation method. A series of characterizations confirmed the strong synergistic effect between BiOBr and NH2-MIL-125(Ti). In rhodamine B (RhB) degradation experiments, the composite photocatalyst with a mass percent of 7 wt% NH2-MIL-125(Ti) exhibited an improved photocatalytic activity compared to pristine BiOBr and NH2-MIL-125(Ti). Furthermore, the enhanced photocatalytic performance under visible light illumination could be attributed to the Ti3+–Ti4+ intervalence electron transfer and synergistic effect between NH2-MIL-125(Ti) and BiOBr, and also resulted in a separation efficiency of photo-generated electron–hole pairs during the photocatalytic reaction. This study can open up numerous opportunities for the development of various MOF-based visible light photocatalysts when combined with 2D bismuth oxyhalide materials for applications in environmental cleaning. [ABSTRACT FROM AUTHOR]

Based on Cd(NO3)2·4H2O and 4,4′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H3cpbda), two isomeric coordination polymers, {[Cd1.5(cpbda)(bpa)(H2O)2]·1.5H2O}n (1), [Cd(H2cpbda)2(bpa)0.5(H2O)]n (2), were synthesized by using different solvent-systems. The complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. Owing to the obvious structural difference between the two isomeric complexes, the further fluorescence sensing and dye selection and adsorption were investigated. The 3D tight stacking structure of 1 strengthened the fluorescence emission and the loose 2D layer structure of 2 generated the active selection and adsorption of the Malachite Green Oxalate (MGO) dye. [ABSTRACT FROM AUTHOR]

Spinous α-Fe2O3 hierarchical structures grown on a Ni foam substrate have been successfully obtained by a facile one-step hydrothermal method. The prepared products are functionalized as supercapacitor electrodes without adding any ancillary materials such as carbon black or binders. Their electrochemical properties show a high discharge areal capacitance (681 mF cm−2 at 1 mA cm−2), good rate performance (495 mF cm−2 at 5 mA cm−2) and long-term cycling stability (23.9% loss after 6000 repetitive cycles at 1 mA cm−2). Such excellent supercapacitive characteristics could be mainly attributed to their unique spatial structures which provide many active sites and enhance the combination between the electrode and Ni foam to support fast ion and electron transfer. In addition, the prepared α-Fe2O3 product is also used as a photocatalyst for the photocatalytic degradation of several harmful organic dyes under visible light illumination. By comparing the photocatalytic performance towards Congo red dye with other photocatalysts, it was observed that the prepared spinous α-Fe2O3 hierarchical structure exhibited superior photocatalytic performance. Finally, photocatalytic recycle tests showed the superiority of the prepared α-Fe2O3 product. This demonstrates that spinous α-Fe2O3 structures could be promising candidate materials for high-capacity, low-cost supercapacitor electrodes and environmentally friendly photocatalysts. [ABSTRACT FROM AUTHOR]

Magnetic porous carbon composites are promising materials in various applications, such as adsorbents, supercapacitors and catalyst supports, due to their high surface area, thermal and chemical stability, and easy separation. However, despite the increasing number of reports of magnetic porous carbon composites, the preparation of these materials with environmentally friendly procedures still remains a great challenge. Herein, we report a facile method to prepare a magnetic porous carbon composite with high surface area from a Fe-based metal–organic gel (MOG) template, an extended structure of a metal–organic framework (MOF). The obtained magnetic porous carbon composite was applied to remove organic dyes from an aqueous solution by selecting methyl orange (MO) as a model molecule. It exhibits excellent adsorption capacity (182.82 mg g−1), fast adsorption kinetics (8.13 × 10−3 g mg−1 min−1), and a perfect magnetic separation performance for the MO removal. This study demonstrates a new way to achieve clean synthesis of magnetic porous carbon materials, and opens a new door for the application of MOGs in organic dye removal. [ABSTRACT FROM AUTHOR]

A simple and facile one-step method for the synthesis of an organic dye-functionalized polyoxometalate (POM) hybrid with visible-light photo-response was reported. The POM hybrid was fully characterized via single crystal XRD, powder XRD, FTIR and elemental analysis. The reaction of the organic dye with inorganic salts gave the dye-functionalized POM (MoBB3), in which the POM cluster was formed in situ. The electronic absorption peak of this hybrid was successfully extended beyond 680 nm. Photoelectrochemical measurement indicated that MoBB3 was photoresponsive under visible-light illumination, suggesting that it is an n-type (electron conductive) semiconducting material. This result might offer a method for the design of novel organic dye-functionalized POMs for photoelectric applications. [ABSTRACT FROM AUTHOR]

A homochiral three-dimensional framework material, [Cu7(4-bpt)6(CN)(H2O)] (1) (4-bpt = 3,5-bis(4-pyridyl)-1,2,4-triazole), has been successfully synthesized by solvothermal reaction, which is generated through an unusual spontaneous asymmetrical crystallization from achiral precursors, and its photocatalytic properties in degradation of organic dyes are also investigated. [ABSTRACT FROM AUTHOR]

A series of 2D layered isostructural coordination complexes {[M3(L)2(H2O)6]·H2O}n (M = Mn (1), Mn0.7Co0.3 (2), Mn0.5Co0.5 (3), Mn0.3Co0.7 (4), and Co (5), respectively, H3L = 1-aminobenzene-3,4,5-tricarboxylic acid) have been synthesized under hydrothermal conditions, and applied to catalyze the reaction of degenerating organic dyes under visible light irradiation. The photocatalytic results indicate that complex 5 exhibits good photocatalytic properties in the presence of H2O2, while 1 can restrain the photodegradation of organic dyes. Remarkably, when Mn ions are gradually replaced by Co ions in the complexes, the photocatalytic activities of 1–5 turn from inhibition to promotion, which is a controllable regulation of photocatalytic properties via changing metal ions. Moreover, by using novel magnetic analysis methods and diffuse-reflectance UV/Vis spectra analysis methods, we explain the influence of central metal ions on the photocatalytic performance. [ABSTRACT FROM AUTHOR]

The hydrothermal reactions of a mixture of (NH4)6Mo7O24·4H2O, Cu(Ac)2·H2O and 3-bpo ligands at different temperatures result in the isolation of two novel inorganic–organic hybrid materials containing different but related isopolymolybdate units, [Cu(3-bpo)(H2O)(Mo4O13)]·3H2O (1) and [Cu2(3-bpo)2(Mo6O20)] (2). The {Mo4O13}n chains in 1 and unprecedented [Mo6O20]4− isopolyhexamolybdate anions in 2 are linked by octahedral Cu2+ ions into two-dimensional hybrid layers. Interestingly, 3-bpo ligands in both 1 and 2 are located on either side of these hybrid layers and serve as arched footbridges to link Cu(ii) ions in the layer via pyridyl N-donors, and at the same time connect these hybrid layers into 3D supramolecular frameworks via weak Mo…Noxadiazole bonds. Another important point for 1 is that water clusters are filled in the 1D channels surrounded by isopolytetramolybdate units. In addition, dye adsorption and photocatalytic properties of 1 and magnetic properties of 1–2 have been investigated. The results indicated that complex 1 is not only a good heterogeneous photocatalyst in the degradation of methyl orange (MO) and methylene blue (MB), but also has high absorption capacity of MB at room temperature and can selectively capture MB molecules from binary mixtures of MB/MO or MB/RhB. All MB molecules absorbed on 1 can be completely released and photodegraded in the presence of adequate peroxide. The temperature dependence of magnetic susceptibility revealed that complex 2 exhibits antiferromagnetic ordering at about 5 K, and a spin-flop transition was observed at about 5.8 T at 2 K, indicating metamagnetic-like behaviour from antiferromagnetic to ferromagnetic phases. [ABSTRACT FROM AUTHOR]

A novel strategy for the stitching of a tripodal ligand into a bi-metallic two-dimensional (2D) coordination polymer has been reported. The reaction of 5-nitrosalicylaldehyde based ligand H3L with nickel acetate resulted in the metal functionalized 2D extended network via potassium induced activation of the nitro group of the ligand. The compound is highly active towards photo-degradation of organic dyes. [ABSTRACT FROM AUTHOR]

The application of nanohybrids in water treatment by the catalytic degradation of various pollutants has attracted much attention from researchers. Here, the Pd/Fe3O4-PEI-RGO nanohybrids (1d) with high shape selectivity and high specific surface area have been synthesized by the dispersion of Pd NPs and Fe3O4 NPs on PEI modified graphene oxide sheets. These nanohybrids show superior catalytic activity toward methylene blue with a high degradation efficiency above 99% in the presence of NaBH4 in aqueous solution, which is attributed to the effects of the Pd NPs supported on reduced graphene oxide nanosheets. Meanwhile, the 1d catalyst can be easily separated from the reaction mixture by applying an external magnetic field. The catalyst was recycled nine times without showing any significant loss in its activity. Such features enable this catalyst for promising application in catalysis, environment, and new energy fields. [ABSTRACT FROM AUTHOR]

Chalcogenolate clusters can be interlinked with organic linkers into semiconducting coordination polymers with photocatalytic properties. Here, discrete clusters of Cd8S(SPh)14(DMF)3 were interlinked with 4,4′-bipyridine into a one dimensional coordination polymer of [Cd8S(SPh)14(DMF)(bpy)]n with helical chains. A stepwise mechanism for the assembly of the coordination polymer in DMF was revealed by an ex situ dynamic light scattering study. The cluster was electrostatically neutral and showed a penta-supertetrahedral structure. During the assembly each cluster was interlinked with two 4,4′-bipyridine molecules, which replaced the two terminal DMF molecules of the clusters. In their solid-state forms, the cluster and the coordination polymer were semiconductors with wide band gaps of 3.08 and 2.80 ev. They photocatalytically degraded rhodamine B and methylene blue in aqueous solutions. The moderate conditions used for the synthesis could allow for further in situ studies of the reaction-assembly of related clusters and coordination polymers. [ABSTRACT FROM AUTHOR]

New photocatalysts (La3+/Ce3+-H3PW12O40 and La3+/Ce3+-H3PW12O40) were prepared, and the degradation activity of these products was evaluated. These photocatalysts were synthesized by the hydrothermal method assisted by PEG-1000 from the reactions of LaCl3 or CeCl3 and phosphotungstic acid. The prepared catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), ultraviolet-visible diffuse reflection spectroscopy (UV-vis) and thermal gravimetric analysis (TGA). The catalytic activity of La3+/Ce3+-H3PW12O40 and Ce3+/Ce3+-H3PW12O40 was evaluated by adopting methyl orange (MO) and Rhodamine B (RhB) as model dyes, and the reaction was carried out under UV- and visible light irradiation. [ABSTRACT FROM AUTHOR]