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The interaction of decavanadate with the cationic organic dyes methylene blue (MB), toluidine blue (TB) and rhodamine B (RB) was explored. For that purpose, a novel decavanadate salt (2,3-ampH)6[V10O28]·4H2O (2,3-ampV10), where 2,3-ampH+ = 2-amino-3-methylpyridinium, and two salts with the organic dyes (MB)4[H2V10O28]·10.8H2O (MBV10) and (TB)4(H2V10O28)·10H2O (TBV10) were synthesized. The compounds were characterized by elemental analysis, powder X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and infrared spectroscopy. The salts 2,3-ampV10 and MBV10 were also characterized by single-crystal X-ray diffraction, while TBV10 was isolated as an amorphous solid. The supramolecular features of MBV10 showed columns of MB cations connected to V10 through H-bond interactions that resulted in channels filled with water molecules. The absorption spectrum of MBV10 was studied by density functional theory (DFT) calculations at the X3LYP/def2-TZVP level using the crystallographic data. The efficacy of 2,3-ampV10 to bleach MB solutions at pH 6.2–6.5 was outstanding, achieving nearly 90% discoloration in only 5 min, presenting moderate efficacy towards TB and quite negligible towards RB. Moreover, a metachromatic effect was observed in the TB solution at pH 3. The IR spectra of the isolated solids and the mass spectra of the supernatants suggest both adsorption and cation exchange as the main responsible processes for the bleaching of MB and TB solutions. The present work has tackled many fronts related to the chemistry of POVs, mainly synthetic, structural, and environmental approaches. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) lamellar membranes have attracted a lot of attention as a possible solution for water purification applications. In this work, asparagine amino acid-modified GO-based membranes (As@GO) are prepared with different thicknesses. The as-prepared As@GO-based membranes are used for the separation of organic dyes and heavy metal ions. The 300 nm-thick As@GO multilayer membrane shows high rejection, i.e., 99.8% and 99.9% of methylene blue (MLB) and rhodamine B (RB) dyes, respectively, along with an exceptional water permeability of ∼1740 ± 10 L m−2 h−1 bar−1. Furthermore, the As@GO membrane also demonstrates excellent rejection of up to 95.6% and 96.7% for cadmium (Cd2+) and lead (Pb2+) ions, respectively. These membranes are also highly stable in water for up to 34 days and do not swell. These results suggest the valuable experimental basis for the design and development of stable GO membranes (GOMs) with high permeability and superior separation selectivity for applications in the separation fields of valuable metal ion extraction from seawater and other wastewater purification, etc. [ABSTRACT FROM AUTHOR]

Organic dye wastewater is a tremendous threat to the environment and human beings. Adsorption as a simple but effective approach for dye removal has attracted widespread attention. However, this promising method is dictated by the development of highly cost-effective adsorbents. Porous organic polymers (POPs) as a new type of porous adsorbent for efficient dye removal have exhibited tremendous potential. However, the scalable production of POPs is still a tremendous challenge, due to the very poor availability of building blocks, often involving tedious synthesis and extremely expensive starting materials. In this study, a kind of carbamate-based POP (CPOP) was designed and synthesized by a simple urethane reaction in one step between 4,4′-diphenylmethane diisocyanate and phloroglucinol without any catalysts. The structure and physicochemical properties of CPOPs were fully characterized and the adsorption and removal performances of organic dyes in water were evaluated. The results indicated that CPOPs with high stability can efficiently and selectively adsorb methylene blue (one of the most widely used dyes) in water. Considering the simple and easy-to-scaleup preparation process and commercially available low-cost raw materials, CPOPs as adsorbents have great potential for use in the treatment of dye wastewater. [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]

Most conventional dye treatment methods have limited efficacy as they are expensive, time-intensive and result in incomplete dye removal from water. Addressing these issues, this work reports the fabrication of a NaTiO3/g-C3N4 heterojunction photocatalyst, which was utilized for the advanced oxidation process under sunlight irradiation to remove crystal violet (CV) and methylene blue (MB) dyes and their binary mixture. The perovskite NaTiO3 is synthesized via a simple hydrothermal method and combined with graphitic carbon nitride, formed through the thermal decomposition of melamine, to fabricate the heterojunction. The scanning electron microscopy (SEM) images reveal that spherical NaTiO3 nanoparticles are aggregated on the sheet-like surface of g-C3N4 and structural analysis utilizing the XRD pattern confirms the formation of a heterojunction. From the Tauc plot the bandgap of the material is estimated to be 2.3 eV. The complete degradation of MB was observed within 25 min, while CV and the binary mixture require 20 min for complete degradation. The high visible light absorption of NaTiO3 and large surface area of g-C3N4 were attributed to the enhanced catalytic performance of the heterojunction. Additionally, scavenger studies indicated that the radical species h+ and +OH played a crucial role in the photocatalytic degradation of the dyes. Reusability studies confirm good stability up to five cycles of dye degradation. The results establish the NaTiO3/g-C3N4 heterojunction as an efficient photocatalyst to remove organic dyes from water, thus having immense potential in water purification. [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]

Environmental problems can potentially be solved by covalent organic frameworks (COFs) that contain predesigned porous architectures. Herein, we developed an amorphous tetrazine–triazine-functionalized covalent organic framework (TzTPT-COF) by performing one-pot polycondensations of 2,4,6-tris-(4-formylphenoxy)-1,3,5-triazine (TPT-CHO) and s-tetrazine-diamine (Tz). The TzTPT-COF possesses ordered-disordered accessible nano-channels with an experimental pore width of 8.5 nm and simulated pore width of 6.4 nm. We detail the characterization of two-dimensional TzTPT-COF with readily accessible 8.5 nm-sized pores, which was subsequently employed as a porous adsorbent for the static and dynamic adsorption of small dye molecules, especially methylene blue from dye-adulterated water. Additionally, the COF quickly attained up to 99% of its maximum adsorption capacity within 15 min. The thermal stability of the COF was maintained, with the onset of gradual weight loss observed at 280 °C. Furthermore, the COF exhibited no crystallinity and possesses a mesoporous structure. The experimental findings and in silico simulation revealed that to create COF-based adsorbents with effective dye adsorption capabilities, it is necessary to concurrently consider the inherent pore size of the COF material as well as the size of the organic dye molecules. The TzTPT-COF has a great deal of potential as an adsorbent material for eliminating cationic dyes and other organic pollutants from wastewater due to the high adsorption efficiencies, ultrafast kinetics, and outstanding reusability. Hence, the present findings suggest that COFs can also be proven to be highly versatile porous materials for various environmental remediation applications. [ABSTRACT FROM AUTHOR]

The slow kinetics of the Co3+/Co2+ catalytic redox cycle on the surface of Co-based solid catalysts greatly limits their application in sulfate radical-based advanced oxidation processes. To overcome this challenge, nanoparticle-assembled rod-like S-doped Co3O4 (S-Co3O4) with abundant oxygen vacancies (OVs) and a mesoporous structure was prepared to activate peroxymonosulfate to degrade various organic dye contaminants. The abundant OVs and good charge transfer capability of S-Co3O4 accelerated the Co3+/Co2+ redox cycle due to the incorporation of S atoms, which improved the Co2+ recovery. The S-Co3O4 catalysts exhibited excellent catalytic activities, and the methylene blue (MB) degradation rate reached 100% within 6 min. The degradation rate constant of the catalytic reaction for the S-Co3O4 + PMS system (0.78 min−1) was 30 times higher than that of the Co3O4 + PMS system (0.026 min−1), which may be due to the synergy between the high Co2+ content, abundant OVs, and large surface area. After six consecutive cycles, the MB degradation efficiency still reached 94.5%, and the cobalt leaching of S-Co3O4 was only 0.42 mg L−1. In the S-Co3O4-activated PMS system, SO4˙− and 1O2 were the main active species, but 1O2 played the main role in contaminant degradation. This study provides a novel method for accelerating Co3+/Co2+ circulation and reducing Co ion leaching from the surface of heterogeneous Co-based catalysts to substantially enhance their performance. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized a facile tyrosine derivative based compound (2-QY), which can act both as a gelator and a reducing agent. 2-QY can assemble to form a functional metallohydrogel (2-QY-Au) in the presence of HAuCl4 under mild conditions (room temperature, aqueous solution, and simple sonication treatment). Au nanoparticles (Au NPs) can be in situ formed and dispersed uniformly in the gel system, which did not require an external reducing agent and a stabilizing agent. The obtained 2-QY-Au NP@metallohydrogel can be used as a catalyst to degrade a variety of dyes, such as methyl orange, methyl green, reactive black 5, reactive orange 16, and p-nitrophenol. In particular, it exhibits excellent catalytic activity towards degradation of methylene blue in the presence of NaBH4, with a kapp value (13.23 ± 0.21 s−1) higher than those of most of the reported catalysts in the literature. Moreover, 2-QY-Au NPs have good biocompatibility and exhibit antibacterial activity against E. coli and B. subtilis. Therefore, the 2-QY-Au NP@metallohydrogel could be used as an effective catalyst for the degradation of pollution containing organic dyes, as well as for potential applications in the biomedical field. [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]

We demonstrate a low-cost, simple-operation, and environmentally friendly magnetic grinding synthetic process to prepare nontoxic copper sulfide-based composites with photocatalytic activity. Using this efficient approach, CuS/ZnS and CuS/CdS composites were successfully synthesized from elemental powders without using any other additives or solvents. The formation of metal sulfides was confirmed using a series of characterizations. The photocatalytic activities of the as-prepared materials were evaluated by the degradation of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) dyes in the presence of hydrogen peroxide (H2O2), which served as an oxidant under visible irradiation. The degradation efficiencies of MB and RhB by CuS/ZnS and CuS/CdS composites were more than 95% in 30 min and the degradation efficiency of MO was more than 85% in 90 min. The photocatalytic activities of the CuS/ZnS and CuS/CdS composites were better than those of pure metal sulfides. In addition, the CuS/ZnS and CuS/CdS composites showed good stability toward photocatalytic degradation and their main reactive species for degrading organic dyes are photogenerated hydroxyl radical (˙OH). Reasonable photocatalytic reaction mechanisms are proposed to explain the photocatalytic processes of the CuS/ZnS and CuS/CdS composites. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are efficient semiconductor materials with superior catalytic activity and adjustable band gaps for the efficient degradation of organic pollutants in water. However, the synthetic yield of COF is generally small and only exists in the laboratory stage. In this paper, we introduced an emulsifier-mediated strategy into the synthesis of a COF for the first time and synthesized a COF with higher crystallinity and a higher synthetic yield of 84.7%. The specific surface area of BJH was also increased from 388.7 m2 g−1 to 1678.5 m2 g−1 and the photocatalytic degradation efficacy of 10 ppm methylene blue was increased from 26% to 100% within 50 min. This work provides a promising strategy to achieve a COF with a higher surface area, synthetic yield and photocatalytic efficacy via the emulsifier-mediated strategy, which would promote the industrial and practical production of COFs. [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]

A multifunctional anionic Zn-MOF, formulated as {[NH2(CH3)2][Zn7(μ3-OH)3(L)6(H2O)]·24H2O·6DMA}n (1) (where H2L = 6-methoxy-2,2′-sulfone-4,4′-dicarboxylic acid and DMA = dimethylacetamide) has been solvothermally synthesized, which is based on rare heptanuclear [Zn7(μ3-OH)3(COO)12] clusters possessing large 3D intersecting channels. Through a cation-exchange process, 1 can selectively adsorb cationic organic dyes, and the adsorption capacities for methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) are 219.9, 114.6 and 197.6 mg g−1, respectively. Moreover, the obtained RhB@1 composite features dual-emissive characteristics and can serve as a dual-channel sensor for selective sensing of traces of NF antibiotics (NFT and NFZ), with detection limits of 0.89 μM and 0.95 μM, respectively. The mechanism study shows that the quenching process is mainly ascribed to the synthetic effect of IFE and FRET. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs), as a novel platform for the synthesis of metal nanoparticles, display abundant properties of adjustable porosity, high crystallinity and large surface area. In particular, three-dimensional (3D)-COFs are unique skeletons with greater surface areas, numerous easily accessible active sites and interpenetrating channels compared to 2D-COFs. These eminent properties of 3D-COFs are very beneficial for anchoring metal nanoparticles, and effectively restrict the size and growth of nanoparticles, enhancing the catalytic performance. In this study, we prepare hybrid nano-materials (denoted as AgNPs-3D-COF) based on Ag nanoparticles and a hydroxy functional 3D-COF. The strong coordination between OH groups and metal Ag and finite aperture generate uniform and small size Ag nanoparticles. When applied to the catalytic reduction of 4-nitrophenol and the degradation of organic dyes, namely methylene blue and Congo red, AgNPs-3D-COF delivers high activity and enduring cycling stability. We expect that this study can offer a strategy for constructing advanced heterogeneous metal nanoparticle catalysts and accelerate the advancements of 3D-COFs. [ABSTRACT FROM AUTHOR]

The crucial role of supramolecular interactions in determining the supramolecular layer architecture of the heteroleptic Cu(II) complex [Cu(L)(imid)(ClO4)]n synthesized from ortho-vaniline based Schiff base and imidazole co-ligands has been investigated through a detailed study of Hirshfeld surface analysis which is at present of huge interest in crystal engineering. The X-ray study showed that the major interactions which particularly take part in the 1D self-assembly include conventional and non-conventional hydrogen bonding and parallel-displaced π⋯π stacking interactions to form a polymeric ladder-like structure of the studied complex. In the presence of supramolecular assemblies, the synthesized Cu(II) complex efficiently degrades methylene blue (MB) (35%) and ethidium bromide (EB) (38%) dyes at 290 minutes under sunlight irradiation. The complex exhibited the highest degradation efficiency of about 95–96% after 48 hours of sunlight exposure, demonstrating the important role of this supramolecular copper(II) complex in effective photo degradation of MB and EB organic dyes under sunlight with its potential application in wastewater treatment and purification. The high performance of the complex is due to its highest photoluminescence lifetime of 22.57 ns. [ABSTRACT FROM AUTHOR]

Multinuclear cluster-based metal–organic frameworks (MOFs) have shown excellent activity in toxic chemical removal from wastewater due to their high porosity, functionality and water stability. In this regard, a highly porous, water-stable Fe-MOF was fabricated and the efficiency of its acyl amide-functionalized pores for organic dye removal was investigated. Different anionic and cationic dyes including methyl orange (MO), methyl red (MR), congo red (CR), rose-bengal B (Ros B), rhodamine B (Rhod B) and methylene blue (MB) were applied to determine the Fe-MOF efficiency. The presence of acyl amide improves the host-guest interaction of the framework towards anionic dyes, specifically MO with an adsorption capacity of 232.5 mg g−1. Interestingly, the Fe-MOF shows one of the fastest adsorptions of MO with a kinetic constant of 0.013 g mg−1 min−1 which is faster than those of some of the well-known MOFs such as UiO-66, MOF-235, MIL-53, MIL-101, UiO-66-NO2 and ZIF-67. The adsorption mechanism, uptake kinetics and selectivity of the framework for different dyes were also studied. Overall, water stable Fe-MOF with a high permanent porosity as well as rational decoration of pores with specific functions, improved the size and charge selective dye removal by the preferred H-bonding and π–π interactions. [ABSTRACT FROM AUTHOR]

A core–shell Fe3O4@C nanocomposite consisting of a layer of amorphous carbon functionalized on the Fe3O4 surface has been synthesized via a simple hydrothermal process of a suspension of Fe3O4 nanoparticles and glucose. Using this approach, the thickness of the amorphous carbon shell can be well controlled by changing the mass ratio of Fe3O4 nanoparticles to glucose. The specific characteristics of Fe3O4@C were also analyzed. The results obtained revealed that the adsorption of methylene blue (MB) onto the Fe3O4@C nanosorbent is strongly dependent on the thickness of the carbon shell. The Fe3O4@C nanosorbent could be recovered for reuse with 83% effective removal at the 5th cycle. With its excellent performance, Fe3O4@C nanocomposite has great potential applications as a smart nanosorbent, including high adsorption capacity, recoverability and recyclability for organic dye removal. [ABSTRACT FROM AUTHOR]

Four new Keggin-type polyoxometalate (POM)-based metal–organic complexes constructed from two flexible bis(pyrazine)–bis(amide) ligands N,N′-bis(2-pyrazinecarboxamide)-1,2-ethane (bpae) and N,N′-bis(5-methyl-2-pyrazinecarboxamide)-1,2-ethane (bmpae), namely, [Cu2(bpae)2(H2O)2(PMoVI9MoV3O39)]·5.5H2O (1), [Cu2(bpae)2(SiMo12O40)]·3H2O (2), {[Co2(bmpae)2(H2O)4](SiW12O40)}·1.5H2O (3), and [Cu2(bmpae)2(SiW12O40)]·8H2O (4), have been hydrothermally synthesized and structurally characterized. Complex 1 is a [PMoVI9MoV3O39]4− (PMo12)-based 3D coordination framework, which is constructed by three kinds of 1D chains: [Cu(bpae)]n2n+, [PMo12]n4n− and [Cu(PMo12)]n2n− chains. Complex 2 shows a 2D structure, which is composed of tridentate [SiMo12O40]4− anions (SiMo12) and [Cu(bpae)]n2n+ chains. Complex 3 is a 0D structure, which is constructed from [Co2(bmpae)2]4+ binuclear rings and discrete [SiW12O40]4− (SiW12) anions. In 4, the 1D [Cu(bmpae)]n2n+ chains are connected by the SiW12 anions to produce a 2D structure. The diverse structures of 1–4 demonstrate that the different metal ions and POMs have pivotal influences on the formation of the final coordination frameworks. In this work, the adsorption performances of 1–4 for the organic dyes gentian violet (GV) and methylene blue (MB) were examined, and 1 possesses good reusability. In addition, 1–4 can be employed as amperometric sensors to identify multiple analytes (BrO3−, NO2−, Cr(VI) and Fe(III) ions) and possess good selectivity in the presence of some other ions. [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]