Synthesis and Photocatalytic Properties of Four Coordination Compounds Constructed from Two Benzimidazole-Based Asymmetric Polyazocyclic Ligands.

In this paper, two benzimidazole derivative ligands were obtained using o-phenylenediamine and n-pyridine formaldehyde (n = 3, 4) by amine-aldol condensation reactions, which were reacted with selected inorganic metal salts by ambient temperature volatilization method to give compounds 1-4: {[(L1)6]·[Cu8I8]} (1), {[L1]·[CuBr]·H2O} (2), {[L2]·[CuBr]}n(3), and {[(L2)4]·[Cu4I4]} (4). They were characterized by IR, UV-Vis absorption spectroscopy, thermogravimetric analysis, and single crystal X-ray analysis. Simultaneously, compounds 1-4 were found to possess photocatalytic degradation of ciprofloxacin (CIP) by preliminary experimental investigations.

Antifoaming Agent for Lubricating Oil: Preparation, Mechanism and Application.

In the process of using lubricating oil, it is inevitable that bubbles will be produced, which can not only accelerate the oil's oxidation and shorten the oil change cycle but also reduce its fluidity and lubricity, aggravate the wear of mechanical parts and produce an air lock that interrupts the oil pump supply and causes an oil shortage accident. This paper mainly and comprehensively discusses the foaming process and its harm, the defoaming mechanism and defoaming method of lubricating oil, more specifically, the synthesis, application, advantages, disadvantages and current situation of three kinds of chemical defoaming agents, namely silicone defoaming agent, non-silicone defoaming agent and compound defoaming agent. Finally, the paper looks forward to the future development of special defoaming agents for lubricating oil.

Two New 1D Supramolecular Compounds Based on PbI2 for Efficient Iodine Capture.

Two new inorganic-organic hybrid crystals based on PbI2 were assembled through the solvent evaporation method, namely, {[L1]·[Pb2I6]}n (1) and {[L2]2·[Pb3I10]}n (2). L1-L2 are a series of multivalent nitrogen-containing cationic ligands. Compounds 1-2 were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR, powder X-ray diffraction, and thermogravimetric microanalysis. The results showed that the adsorption rate of 80 mg compound 1 to iodine reached 96.59%, indicating a high iodine capture performance in cyclohexane solution. In the meantime, the adsorption kinetics is most suitable for a pseudo-second-order model, and the adsorption process is mainly chemisorption. Adsorption thermodynamics is most suitable for the Langmuir model, indicating that adsorption occurs on the surface of the monolayer. According to the adsorption mechanism, it can be inferred that the structure of compound 1 contains amino, benzene, N heterocyclic, and other active groups, that is, indirectly increases the adsorption site with iodine, and the chemical reaction with iodine improves the removal rate of iodine in cyclohexane solution. In addition, compound 1 was found to have good iodine adsorption and recyclability by cyclic experiments. Therefore, the synthesized compound 1 can be used as a potential and excellent iodide capture adsorbent, which may have a good application prospects in the future.

M-Carboxylic Acid Induced Formation of New Coordination Polymers for Efficient Photocatalytic Degradation of Ciprofloxacin.

Four new 2−3D materials were designed and synthesized by hydrothermal methods, namely, {[(L1·Cu·2H2O) (4,4-bipy)0.5] (ß-Mo8O26)0.5·H2O} (1), {[(L1·Cu)2·(4,4-bipy)] (Mo5O16)} (2), {Co(L1)2}n (3), and {[(L1)2][ß-Mo8O26]0.5·5H2O} (4). [L1=5-(4-aminopyridine) isophthalic acid]. The degradation of ciprofloxacin (CIP) in water by compounds 1−4 was studied under visible light. The experimental results show that compounds 1−4 have obvious photocatalytic degradation effect on CIP. In addition, for compound 1, the effects of temperature, pH, and adsorbent dosage on photocatalytic performance were also investigated. The stability of compound 1 was observed by a cycle experiment, indicating that there was no significant change after three cycles of CIP degradation.

A Review of Crystalline Multibridged Cyclophane Cages: Synthesis, Their Conformational Behavior, and Properties.

This paper reviews the most stable conformation of crystalline three-dimensional cyclophane (CP) achieved by self-assembling based on changing the type of aromatic compound or regulating the type and number of bridging groups. [3n]cyclophanes (CPs) were reported to form supramolecular compounds with bind organic, inorganic anions, or neutral molecules selectively. [3n]cyclophanes ([3n]CPs) have stronger donor capability relative to compound [2n]cyclophanes ([2n]CPs), and it is expected to be a new type of electron donor for the progress of fresh electron conductive materials. The synthesis, conformational behavior, and properties of crystalline multi-bridge rings are summarized and discussed.

Multiple Responsive CPL Switches in an Enantiomeric Pair of Perovskite Confined in Lanthanide MOFs.

Circularly polarized luminescence (CPL) switches have attracted widespread attention due to their potential applications in advanced information technologies. However, the design and fabrication of solid-state multiple-responsive CPL switches remain challenging. Here, through self-assembly of chiral metal-organic frameworks (MOFs) and perovskite nanocrystals (NCs), a pair of crystalline enantiomeric (P)-(+)/(M)-(-)-EuMOF⊃MAPbX3 (MA = CH3 NH3 + , X = Cl- , Br- , I- ) adducts is prepared, where the achiral MAPbBr3 perovskite NCs embedded into chiral MOFs inherit the chirality of host MOFs by host-guest EuBr and PbO coordination bonds, which is demonstrated by synchrotron-radiation-based X-ray absorption spectroscopy. The chiral adducts show enhanced photoluminescence quantum yield (PLQY), good thermal stability of CPL in air, and photoswitchable CPL properties upon altering different UV irradiation. Based on two chiral emission centers and their different characteristics, reversible CPL switches are realized upon a diversity of external stimuli, for example, chemicals (water /CH3 NH3 Br solution) or temperatures (room temperature/high temperature). Benefiting from the extraordinary stimuli-responsive and highly reversible switchable CPL, multiple information encryptions and decryptions integrated with CPL, together with a chiroptical logic gate are successfully designed. This work opens a new avenue to generally fabricate solid-state CPL composite materials and develops new applications based on switchable CPL.

A stable and highly luminescent 3D Eu(III)-organic framework for the detection of colchicine in aqueous environment.

The metal-organic framework materials have an important application as sensors. In this work, a microporous three-dimensional (3D) Eu(III)-organic framework (Eu-MOF), [Eu2(3,5-bct)(phen)2(ox)2(H2O)]·H2O, was constructed from 3,5-bis(3'-carboxyphenyl)-1,2,4-triazole (3,5-H2bct), oxalate (ox) and 1,10-phenanthroline (phen) as a luminescent sensor. The free volume was found to be 15.7% per unit volume ignoring the free water molecules. The Eu-MOF showed bright red light due to the emission at 622 nm (5D0 → 7F2 transition) of the Eu(III) with high quantum yield (QY, 52.51%). The Eu-MOF exerted high luminescence stability in common organic solvents as well as aqueous solutions within a wide pH range from 4 to 11. Based on the luminescent Eu-MOF, the sensing behavior for colchicine in the aqueous environment was studied. Highly selective and sensitive detection (LOD = 2.43 × 10-5 mol L-1) of colchicine was observed by the Eu-MOF even in the presence of potential interfering components. The sensing mechanism for colchicine was investigated by experimental and theoretical results. It is worth noting that a film (Film@Eu-MOF) prepared by loading Eu-MOF showed intense characteristic red light emission under UV light. The luminescence color changed immediately from red to colorless when the Film@Eu-MOF came in contact with colchicine. Highly sensitive and rapid detection of colchicine in wastewater was achieved using this Film@Eu-MOF, which could be identified by the naked eye. The experimental results suggest that the synthesized Eu-MOF has potential application as a luminescent sensing material for pollutants in the environmental system.

Intermolecular interactions, photocatalysis and THz-TDS interrelationships for lanthanide phosphine oxide complexes based on {PW12}.

A series of rare earth complexes containing (α-PW12O40)3- and PO ligand are synthesized by water bath in 70 °C, [Ln(OPPh3)4(H2O)3](PW12O40)·4CH3CN (Ln = La, Pr, Nd, Sm, Gd, Tb, Ho 1-7) (OPPh3 = Triphenylphosphine oxide, {PW12} = phosphotungstic acid). The precise structures are confirmed by X-ray single crystal diffraction and the result shows all complexes are isostructural. Complexes 1-7 are fully characterized by PXRD, FT-IR, TGA, UV diffuse reflectance spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 3 exhibits the highest photocatalytic degradation efficiency for methylene blue (MB) in this series of complexes. The experimental results showed that the photodegradation efficiency can remain constant at the level of 95% after five consecutive cycles. The photocatalytic reaction kinetics and mechanism of complexes were investigated. Additionally, complexes also exhibit photocatalytic hydrogen evolution activity. THz-TDS was used to characterize the complexes and its raw materials, the characteristic peaks of OPPh3 (broad peak at 1.20 THz) and phosphotungstic acid (sharp peaks at 0.23, 0.32 THz) were obtained.

Facile high yield, excellent catalytic performance of polyoxometalate-based lanthanide phosphine oxide complexes: Syntheses, structures, photocatalysis and THz spectra.

Water pollution, which continuously threatens human health and the sustainable development of society, has become a major concern. Photocatalytic degradation is an effective strategy to remove organic dyes from wastewater. For this strategy, it is crucial to select the appropriate catalyst. Using triphenylphosphine oxide (OPPh3) as the ligand, phosphomolybdic acid as the anion template, three new lanthanide complexes [Ln(OPPh3)4(H2O)3](PMo12O40)∙4C2H5OH (1-3) (Ln = Sm, Gd, Tb) were synthesized. The raw materials for the reaction are cheap and readily available. The convenient synthesis method is environmentally friendly, with high yield (70%-80%). Complexes 1-3 are all seven-coordinated mononuclear structures centered on lanthanide ions, [PMo12O40]3- anions and solvent molecules are not coordinated with metal ions. These mononuclear structures eventually form complicated 3D supramolecular structures through hydrogen bonds, Mo-O … π or C-H … π weak interactions. Complexes 1-3 photocatalytic degradation of MB have high removal rates, as catalysts have enough stability to be reused, and can be used as excellent catalysts for the degradation of dye molecules in sewage. Among them, the removal rate of MB by photodegradation of complex 2 was highest (99.50%). In addition, the effects of different initial concentrations of MB solution and different types of organic dyes on the photocatalysis experiment were investigated. The photocatalytic reaction mechanism of complexes 1-3 was also studied. Due to the similar structures of complexes 1-3, they have almost the same THz absorption spectra with different absorption intensity, which may be attributed to the difference of the number of weak interactions. Therefore, terahertz spectroscopy can be used as a sensitive method to distinguish and determine small differences between lanthanide-organic complexes. This is the first time that this spectrum has been used to characterize lanthanide phosphine oxide complexes modified by [PMo12O40]3-.

Preparation of 2D supramolecular material doping with TiO2 for degradation of tetracycline.

Anatase TiO2 photocatalyst supported on [BMPP]2[2D-Mo18O56] (BMPP = 1, 3-bis(4-methylpyridine) propane dibromide) was successfully prepared by hydrothermal method. The composites were characterized by field emission scanning electron microscopy (SEM), X-ray diffractometer (XRD), infrared spectroscopy (IR) and energy-dispersive X-ray spectrometer (EDS). The results show that the high content anatase nanoparticles are uniformly loaded on the polyacid supramolecules to form the composite material. The photocatalytic activity of TiO2/Mo9O28-BMPP towards the tetracyclines (TCs), a model pollutant, has been investigated. The results show that under a 500W high-pressure xenon lamp, 0.15 g TiO2/MoB can degrade 97% of 20 mL (25 mg/L) Tc after 115 min, showing high catalytic activity. In addition, 0.15-TiO2/MoB can be easily separated from the reaction system by centrifugation, and the catalyst still maintains high photocatalytic activity after 3 cycles of tests under the same conditions. This shows that it has the potential for recycling. This research provides a new way for the development of new supported catalysts.

Effective degradation of tetracycline by organic-inorganic hybrid materials induced by triethylenediamine.

As an important advanced oxidation technology for environmental purification, photocatalytic degradation has received extensive attention. Designing and synthesizing a catalyst with high-intensity photocatalytic performance is a very challenging subject. Herein, one polydentate cation was synthesized by 1,4-diazabicyclo[2.2.2]octane (DABCO) and 1, 4-bis (bromomethyl) benzene. Inorganic-organic hybrid compounds 1, 2 were synthesized by hydrothermal and room temperature volatilization with inorganic metal salts, namely, {[L1]0.5·[Cu2Br4]0.5}n (1), {[L1]·[Cu2I4]·CH3CN}n (2). Under visible light, compounds 1 and 2 were investigated for their degradation effects on tetracycline (TC) in water. The experimental results showed that compounds 1 and 2 with appropriate concentration of H2O2 had obvious photocatalytic degradation effect on TC. In addition, the influencing factors of photocatalysis such as the amount of adsorbent, the initial concentration of TC and the different pH value were investigated. The photocatalyst exhibits good stability and cyclability.

Enantiomeric MOF Crystals Using Helical Channels as Palettes with Bright White Circularly Polarized Luminescence.

The host-guest chemistry of metal-organic frameworks (MOFs) has enabled the derivation of numerous new functionalities. However, intrinsically chiral MOFs (CMOFs) with helical channels have not been used to realize crystalline circularly polarized luminescence (CPL) materials. Herein, enantiomeric pairs of MOF crystals are reported, where achiral fluorophores adhere to the inner surface of helical channels via biology-like H-bonds and hence inherit the helicity of the host MOFs, eventually amplifying the luminescence dissymmetry factor (glum ) of the host l/d-CMOF (±1.50 × 10-3 ) to a maximum of ±0.0115 for the composite l/d-CMOF⊃fluorophores. l/d-CMOF⊃fluorophores in pairs generate bright color-tunable CPL and almost ideal white CPL (0.33, 0.32) with a record-high photoluminescence quantum yield of ≈30%, which are further assembled into a white circularly polarized light-emitting diode. The present strategy opens a new avenue for propagating the chirality of MOFs to realize universal chiroptical materials.

Two Nanometer-Sized High-Nuclearity Homometallic Bromide Clusters (M26Br38)12- (M = Cu, Ag): Syntheses, Crystal Structures, and Efficient Adsorption Properties.

The spontaneous formation of discrete spherical nanosized molecules is ubiquitous in nature; however, the actual structural imitation of such high-symmetry polyhedra from the edge sharing of regular polygons has still proved to be elusive. Herein, two high-nuclearity metal clusters, namely (TTB)4·M26Br38 (M = Cu (1), Ag (2), TTB·Br3 = 1, 3, 5-tris(triethylammoniomethyl)benzene tribromide), have been rationally and solvothermally synthesized and structurally characterized. Single-crystal X-ray analysis confirmed that 1 has I4̅3m symmetry with a (Cu25Br34)12- anion shell enwrapping a CuBr4 tetrahedron and 2 has I4̅3m symmetry with a [Ag26Br34]12- anion shell enwrapping a Br4 pyramid. The diffuse-reflectance UV-vis measurements showed that both compounds possess proper semiconductor behaviors with tunable band gaps of 1.87 eV for 1 and 1.90 eV for 2. Interestingly, all the samples feature distinct adsorption speed and compound 1 shows good adsorption activity for methyl orange (MO) under the same reaction conditions. The effects of pH, temperature, and cyclicity on dye adsorption, together with the thermal stabilities and luminescence properties of the compounds, were also studied. From the cyclic adsorption of compound 1 to the anionic dye MO, it was found that the adsorption of MO was good over three cycles, and the third adsorption rate was still 93.90%.

N-Benzyl HMTA induced self-assembly of organic-inorganic hybrid materials for efficient photocatalytic degradation of tetracycline.

Photocatalytic degradation technology (PDT), as one of the most important advanced oxidation technologies (AOTs) for environment-purifying, have drawn great attentions in recent years. It is highly desirable but remains challenging to design and synthesize catalysts with enhanced performance of photocatalysis. Herein, we develop a cation induced self-assembly strategy for the synthesis of two new organic-inorganic hybrid materials ({[BHMTA][Cu2(SCN)3]}n (1), {[BHMTA][Cu2I3]}n (2) BHMTA = N-benzylhexamethylenetetramine bromide). Owing to their unique structural and the desirable composition, the as-prepared organic-inorganic hybrid materials exhibit high efficiency and excellent cycling stability for degradation of tetracycline (TC) under visible light irradiation. In addition, the effect factors for photocatalysis such as catalyst dosage, temperature, and pH were also investigated. The possible mechanism studied shows that superoxide radicals (O2-) and holes (h+) are the main active substances in the degradation process of TC. This work may shed light on preparing new organic-inorganic hybrid materials with promising photocatalysis performance for water purification.

Hybrid Supramolecules for Azolium-Linked Cyclophane Immobilization and Conformation Study: Synthesis, Characterization, and Photocatalytic Degradation.

In this paper, one imidazole macrocyclic divalent cation with a flexible configuration was chosen with the aim of the immobilization of its conformation. Six novel organic-inorganic hybrid supramolecules {([syn/anti-did](CdI4)(C2H3N)} (1), {([syn/anti-did](HgI4)(C2H3N)} (2), {([syn/syn-did](Pb2I8)(PbI5)} (3), {([syn/syn-did](Bi2I8)(BiI5)} (4), {([syn/syn-did](Ag4Br6)} n (5), and {([syn/anti-did](Ag2I4)} (6) [did2+ = (12z, 52z)-11H, 51H-1, 5(1, 3)-diimidazol-3-iuma-3, 7(1, 2)-dibenzenacyclooctaphane-13, 53-diium] have been synthesized through the self-assembly reaction of did2+ with different metals under solvothermal reaction. These compounds have been unambiguously confirmed by powder X-ray diffraction, IR, thermogravimetric and X-ray single-crystal diffraction. Crystallographic analysis shows that the anions of compounds 1 and 2 are isostructural with mononuclear anion structure, the anions of compounds 3, 4, and 6 are of binuclear structure, and compound 5 anion is a one-dimensional anionic chain structure. Imidazole cyclophanes of organic cations may exist in a syn/syn-conformation in 3-5 or syn/anti conformation in 1, 2, 6, but tilting angles in compounds 1-6 were different. This article described the photocatalytic degradation of organic dye in waste water and the optical band gap of compounds 1-6. The calculated semiconductor band gap of compounds 1-6 is smaller than that of TiO2, so compounds 1-6 have semiconductor properties. Compound 1 has the smallest band gap value, and the photocatalytic performance is the best.

Assembly and Adsorption Properties of Seven Supramolecular Compounds with Heteromacrocycle Imidazolium.

Seven supramolecular compounds comprising multivalent imidazolium macrocycles and metal halides, {[MC-IM][Ag2I4]} n (1), {[PC-IM]2[Ag7I11]} n (2), {[ODC-IM][Ag3I7]} (3), {[ODC-IM][Bi2I10]} (4), {[MDC-IM][Bi2I10]} (5), {[PDC-IM][Bi2I10]} (6), and {[MDC-IM][HgI4]} (7), have been synthesized by solvothermal reactions and structurally characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Notably, the three tetravalent imidazolium macrocycles were introduced for the first time and the extended anion structures are featured with three-dimensional coordination networks, one-dimensional chains, or zero-dimensional oligomers. This new study attempts to not only fill the gap in this supramolecular hybrid area that has been neglected but also enrich the type of imidazolium cyclophane. It is important that good efforts were devoted to study the adsorption properties of supramolecular compounds. Compound 5 exhibited great adsorption performance for organic dyes methylene blue, methyl orange, and rhodamine B (RhB) and can be evaluated as a potential candidate for industrial wastewater treatment.

Preparation and Analyses of the Multifunctional Properties of 2D and 3D MOFs Constructed from Copper(I) Halides and Hexamethylenetetramine.

In this article, two two-dimensional and three-dimensional metal-organic frameworks are synthesized by the self-assembly of copper(I) halide and the hexamethylenetetramine (hmt) ligand. Compound 1 is a two-dimensional metal-organic framework composed of a pyramidal Cu4I5 cluster and hexamethylenetetramine, in which hmt-bridged Cu clusters form a two-dimensional (4,4)-connected net with a point symbol of (44·62) (44·62). Compound 2 is a homochiral three-dimensional metal-organic framework material generated through an unusual spontaneous crystallization from achiral precursors. The two compounds were characterized by a series of analyses such as infrared spectroscopy, elemental analysis, circular dichroism spectroscopy, and powder X-ray diffraction. Both of them exhibit unexpected stability under a wide range of conditions of acid and base. In addition, the fluorescence intensity changes regularly under acid-base conditions. Stokes shift shows a good linear relationship with -log [H+], which makes them become promising acid-base sensors. Compounds 1 and 2 also display selective adsorption and a significant degradation effect on the organic dye methylene blue. In addition, the fluorescence study indicated that compound 2 could be used as a sensor to detect Cr3+.

A new nanocrystalline inorganic-organic hybrid exhibiting semiconducting properties and applications.

A new nanocrystalline inorganic-organic hybrid semiconductor [(BV)2(Ag5Br9)]n (1) with an intriguing windmill-like 1-D [Ag5Br9]n(n-) polymeric chain was assembled. Great efforts were devoted to investigate its semiconducting properties and applications, such as photoluminescence, emission decay lifetime, waste water purification, electrochemistry behavior and dielectric properties.

2,3,3-Trimethyl-1-[4-(2,3,3-trimethyl-3H-indol-1-ium-1-yl)but-yl]-3H-indol-1-ium diiodide.

In the crystal of the title salt, C(26)H(34)N(2) (2+)·2I(-), the dication lies on a center of inversion that exists along the mid-point of the butyl chain; its five-membered ring is approximately planar (r.m.s. deviation = 0.011 Å). In the crystal, the iodide anion is disordered over two positions in a 1:1 ratio.

4,5-Dihydro-3a,5a-diazo-niapyrene triiodidocuprate(I).

In the dianion of the title salt, (C(14)H(12)N(2))[CuI(3)], the Cu(I) atom is coordinated by three I(-) ions that define a nearly trigonal-planar geometry; the Cu(I) atom lies 0.1407 (6) Šout of the plane. With the exception of the methyl-ene C atoms, the dication is essentially planar (r.m.s deviation = 0.067 Å). The most significant inter-action between the ions is a C-H⋯I contact.