Solvothermal Conditions Research Articles

Morphology Controlled Deposition of Vanadium Oxide (VOx) Nanoparticles on the Surface of Highly Reduced Graphene Oxide for the Photocatalytic Degradation of Hazardous Organic Dyes.

Semiconducting nanomaterials based heterogeneous photocatalysis represent a low-cost, versatile technique for environmental remediation, including pollution mitigation, energy management and other environmental aspects. Herein, we demonstrate the syntheses of various heterogeneous photocatalysts based on highly reduced graphene oxide (HRG) and vanadium oxide (VOx)-based nanocomposites (HRG-VOx). Different shapes (rod, sheet and urchin forms) of VOx nanoparticles were successfully fabricated on the surface of HRG under solvo-/hydrothermal conditions by varying the amount of water and ethanol. The high concentration of water in the mixture resulted in the formation of rod-shaped VOx nanoparticles, whereas increasing the amount of ethanol led to the production of VOx sheets. The solvothermal condition using pure ethanol as solvent produced VOx nano-urchins on the surface of HRG. The as-prepared hybrid materials were characterized using various spectroscopic and microscopic techniques, including X-ray diffraction, UV-vis, FTIR, SEM and TEM analyses. The photocatalytic activities of different HRG-VOx nanocomposites were investigated for the photodegradation of methylene blue (MB) and methyl orange (MO). The experimental data revealed that all HRG-VOx composite-based photocatalysts demonstrated excellent performance toward the photocatalytic degradation of the organic dyes. Among all photocatalysts studied, the HRG-VOx nanocomposite consisting of urchin-shaped VOx nanoparticles (HRG-VOx-U) demonstrated superior photocatalytic properties towards the degradation of dyes.

Preparation of Trimetallic-Organic Framework Film Electrodes via Secondary Growth for Efficient Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) are promising electrocatalysts for clean energy conversion systems. However, developing MOF-based electrodes with high performance toward oxygen evolution reaction (OER) is still challenging. In this work, a series of MOF film electrodes derived from Ni-btz were prepared by employing the secondary growth strategy under solvothermal conditions. Fe and Co ions were also incorporated into the Ni-btz framework to produce a trimetallic coupling effect to obtain enhanced OER activity. The as-prepared FeCoNi-btz/NF exhibited not only good stability but also excellent OER performance under alkaline conditions. Furthermore, the possible intermediates including metal oxides and metal oxyhydroxides were confirmed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM).

Electrocatalytic hydrogen evolution at carbon paste electrodes doped with a manganese(II) imidazoledicarboxylate complex

Abstract A mononuclear Mn(II) complex [Mn(p-MOPhH2IDC)2(H2O)2]·2(DMF), was synthesized by the reaction of p-MOPhH3IDC (2-(4-methoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid) and Mn(CH3COO)2·4H2O under solvothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV–vis spectroscopy. The structure analysis revealed that the manganese(II) center has a six-coordinated octahedral coordination geometry. The performance of a Mn(II) complex-doped carbon paste electrode (Mn-CPE) in the electrocatalytic hydrogen evolution reaction (HER) was evaluated by linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods. The polarization curve shows that the η 10 298K (overpotential, 10 mA cm−2) of the Mn-CPE was positively shifted by 341 mV compared with the bare CPE (without complex). The Tafel slope of the Mn-CPE was 161 mV dec−1. These data indicate that the Mn-CPE was effective in the HER electrocatalytic reaction. For EIS experiments, the arc diameter of the high-frequency region of the Mn-CPE was much smaller than that of the bare CPE, which further indicates the effective catalytic capacity of the Mn(II) complex for hydrogen evolution. The information obtained from this study will help to expand the application of Mn(II) complexes in the field of electrochemistry.

Solvothermal synthesis of cobalt PCP pincer complexes from [Co2(CO)8

The online version contains supplementary material available at 10.1007/s00706-023-03123-x.

Dual-Modal Biosensor for Staphylococcus aureus Detection Based on a Porphyrin-Based Porous Organic Polymer FePor-TPA with Excellent Peroxidase-like, Catalase-like, and Photoelectrochemical Properties.

Bacterial infections seriously harm human health and cause many severe diseases, which triggered urgent demands to exploit specific and sensitive biosensor strategies for Staphylococcus aureus detection. Here, a colorimetric and photoelectrochemical dual-mode biosensor for S. aureus assay based on FePor-TPA was constructed. 2D FePor-TPA thin film and its bulk powder (FePor-TPA) were synthesized by in situ growth on ITO and a solvothermal condition, respectively, both of which exhibited excellent peroxidase-like and catalase-like activity, originating from their metalloporphyrin linkers. Benefiting from the in situ growth on ITO electrodes, the 2D FePor-TPA thin film also possessed a more ordered stacking mode and in turn exhibited good electrical conductivity, stable initial photocurrent, and high sensitivity to O2. As for bulk FePor-TPA, its porous structure and high specific surface area make it a possible scaffold to load an amount of AuNPs, the rabbit anti-Staphylococcus aureus Rosenbach tropina antibody (Ab2), and GOx for constructing the signal probe (GOx/Ab2@Au@FePor-TPA) and realizing catalytic amplification. With these satisfactory features in mind, the 2D FePor-TPA thin film and its bulk powder (FePor-TPA) were utilized to construct a dual and signal-on bioplatform for sensitively and selectively detecting S. aureus, which, as far as we know, has not been reported.

A new photochromic Mg(II)‐viologen complex with photoswitchable emission and its application in ink‐free printing

AbstractStimulus‐responsive molecular photochromic materials have potential applications in sensor, information storage, and optical switch devices since they undergo reversible color changes upon stimulus from external light. In this work, a viologen‐derived Mg(II) coordination complex with molecular formula [Mg(dpbp)2(H2O)4] (1) has been synthesized from 1‐(3,5‐dicarboxyphenyl)‐4,4′‐bipyridinium chloride (H2dpbp⋅Cl) under solvothermal conditions. Complex 1 has a three‐dimensional viologen‐based hydrogen bond network showing reversible photochromism through radical formation under ultraviolet‐visible light irradiation. Simultaneously, the emission of complex 1 can be reversibly modulated by ultraviolet‐visible light irradiation. Importantly, due to its reversible photochromic properties, practical fading time, and high stability, complex 1 can be used as an ink‐free and erasable printing medium by applying ultraviolet visible light irradiation with a mask.

Na1.5Cs0.5[Al{BO3}{B9O15(OH)3}1/3]: An Acentric Layered Aluminoborate with Nonlinear-Optical Properties.

An acentric aluminoborate (ABO), Na1.5Cs0.5[Al{BO3}{B9O15(OH)3}1/3] (1), has been made under solvothermal conditions. The alternations of AlO4 tetrahedra and BO3 triangles first build up the 2D ABO layer with 6-MR (membered-ring) windows. The fanlike B9O15(OH)3 cluster adorns the layer through Al-O-B linkages, producing a pair of unclosed channels with 7-MR aperture on the lateral side of the layers. The novel B9O15(OH)3 cluster represents the largest oxoboron cluster in the acentric ABO family. 1 not only shows a moderate second-harmonic-generation response of 1.2 times that of potassium dihydrogen phosphate but also has a short cutoff edge below 200 nm, indicating its potential applications in deep-UV regions.

Microporous Cd-MOF as multifunctional material for rapid and visual luminescence sensing of Fe3+, MnO4− and TNP in water and efficient CO2 catalytic conversion

The excessive discharge of Fe3+, MnO4−, TNP and CO2 has resulted in serious environmental problems, which needs to be resolved urgently. Herein, a stable multifunctional Cd2+-organic framework, [Cd(H4L)]·2DMF·8H2O (Cd-MOF-1) was successfully constructed by using the ligand 4,4′,4″,4‴- (1,4-phenylenebis (1H-imidazole-2,4,5-triyl))tetrabenzoic acid (H6L) and Cd(NO3)2·2.5H2O under solvothermal conditions. Structural analysis revealed that Cd-MOF-1 possessed a 3D framework with rich Lewis acid sites (unsaturated Cd2+ sites), Brønsted acid sites (protonated imidazole moieties) and uncoordinated carboxylate oxygens in the hexagonal 1D channels. Moreover, Cd-MOF-1 exhibits good stability in acid-base aqueous solutions with pH = 4–12. Apart from the above structural features, Cd-MOF-1 also displays intense luminescence emission, which can be used to quickly and sensitively detect Fe3+, MnO4−and TNP in aqueous solutions with a high quenching constant and low detection limit even in the presence of other competition ions. Especially, the response time of the Cd-MOF-1 for Fe3+ ions was only 5 s, which is very short response time among the previous MOFs used for Fe3+ detection. Besides, we successfully constructed Cd-MOF-1/PEO mixed matrix films, which can achieve visualized quick detection of Fe3+, MnO4−and TNP in aqueous solutions under the UV lamp. In addition, activated Cd-MOF-1 (called Cd-MOF-1a) with all the guest molecules removed by heating delineates medium shows CO2 gas adsorption and efficient CO2 fixation with epoxide into cyclic carbonate under relatively mild and solvent-free conditions. On top of that, Cd-MOF-1 can be reused at least five cycles with excellent luminescence efficiency and catalytic activity. Furthermore, the possible luminescence sensing and catalytic mechanisms have also been discussed in detail. This work gives a new multifunctional platform for luminescence sensing and CO2 fixation.

Room Temperature On-Surface Synthesis of a Vinylene-Linked Single Layer Covalent Organic Framework.

Conjugated single-layered two-dimensional covalent organic frameworks are flat and extended polymer networks with a unique combination of material properties, giving rise to potential applications in sensing, optoelectronics, and photonics. Despite their great potential, thus far only a few reactions to access such extended conjugated 2D polymers have been reported. Here, the on-surface polymerization of the first vinylene-linked single layered two-dimensional covalent organic framework using reversible Knoevenagel polycondensation under solvothermal conditions is described. Self-assembly of the two monomer building blocks at the solid-liquid interface led to the formation of extended covalent networks at room temperature without the need of additional catalysts or reagents. The described approach grants access to extended conjugated 2D polymers under unprecedentedly mild conditions and paves the way to new hybrid material systems.

Back Cover

The cover picture shows a domino ring opening and coupling reaction of aromatic tricyclic heterocycles with O2 at solvothermal condition, leading to 1,2‐diamidoalkenes derivatives. A series of techniques have been applied to track the reaction process in this gas‐liquid black‐box like system. A seven‐step domino sequence involving a peroxide intermediate has been proposed. This work may provide a unique strategy to develop and design domino reactions starting from heterocycles. More details are discussed in the article by Zeng et al. on page 2089—2094.image

An Important Photocatalysis Oxidation: Selective Oxidation of Aniline to Azobenzene over a {P4Mo6}-based Crystalline Catalyst Under Visible-light Irradiation at Room Temperature.

Selective oxidation of aniline to azobenzene with a higher economic value is significant for modern industrial production. However, the high reaction temperature and undefined catalytic reaction center always limit the promotion of this reaction. Here, we designed and synthesized a new [P4MoV6O31]12--based cobalt-containing complex (Hbiz)5{Co(H2O)3[Co(H2O)2]2}{Co[Mo6O12(OH)3(PO4)(HPO4)3][Mo6O12(OH)3(PO4)2(HPO4)2]}·3H2O (1; biz = benzimidazole) under solvothermal conditions. Using 1 as the photocatalyst, the visible-light-driven conversion of aniline to azobenzene at room temperature was realized for the first time (conversion rate 97%, selectivity 96% of azobenzene, reaction time of 12 h). Additionally, real sunlight irradiation can produce a comparable outcome in 48 h. The mechanism investigation manifested that the Mo and Co centers in 1 acted as Brönsted and Lewis acid centers, synergistically promoting the aniline oxidation reaction. This research advances the application of polyoxometalate-based photocatalysts while also offering a sustainable and effective method for producing azobenzene.

Two solvent-stable Dy2 compounds constructed by a large conjugated diacylhydrazone ligand: Disparate crystal structures and single-molecule-magnet behaviors

Two new dinuclear Dy(III)-based compounds [Dy2(HL)2]·2CH3OH·CH3CN (1) and [Dy2(dbm)2(H2L)2]·6CH3CN (2) (H4L = N', N''-((1E,1′E)-(1,10-phenanthroline-2,9-diyl)bis(methaneylylidene))bis(2-hydroxybenzohydrazide), and Hdbm = dibenzoylmethane) constructed by a large conjugated diacylhydrazone ligand (H4L) have been successfully synthesized under solvothermal conditions. The crystal structures, fluorescent properties, and magnetic properties of the two Dy2 compounds (1 and 2) have been systematically studied. Compounds 1 and 2 show different molecule structures (Compound 1 displays a cattail leaf fan shape, while compound 2 displays a pinwheel-shapedcage). Both compounds 1 and 2 show well solvent stability. Moreover, magnetic properties study reveals that compounds 1 and 2 show single-molecule-magnet behaviors with different energy barrier (the anisotropic barriers (ΔE/kB) is 29.45 K for 1 and 62.52 K for 2. Compounds 1 and 2 show different magnetic properties due to the different chemical environments around the center Dy(III) ions.

Construction of a Cd(II)-Based Metal-Organic Framework for Selective Luminescent Sensing of Chloramphenicol in Milk and Honey Samples

A new and water-stable metal-organic framework, [Cd2(L)2(tmd)]·3H2O (MOF 1), was successfully synthesized by mixed ligands of H2L and tmd under solvothermal condition (H2L= 5-acetamidoisophthalic acid, tmd= 4,4-trimethylenedipyridine). Single-crystal X-ray diffraction shows that the structural unit of MOF 1 is a tetranuclear [Cd4(L)6] primary building unit. Fluorescence sensing experiments revealed that MOF 1 exhibited selectivity and sensitivity detection of Chloramphenicol (CHL) antibiotic in aqueous solutions. The fluorescence quenching effect showed that MOF 1 had a very low detection limit for CHL (LOD= 0.11 μM). More importantly, MOF 1 can be used as a new fluorescence sensor for the detection of CHL in milk and honey samples with very good recoveries of 98.2-103.0 % and 97.0-98.9 %, respectively. Furthermore, the internal filtration effect (IFE) and photoelectron electron transfer (PET) may be responsible for the fluorescence quenching efficiency.

Enhanced photocatalytic degradation performance of new and stable 2D/3D Ln-MOFs for tetracycline under visible light

Rational design of lanthanide metal-organic frameworks (Ln-MOFs) with high stability is of great significance for multifunctional applications. Ln-MOFs have attracted extensive attention in the field of photocatalysis due to their large specific surface area and strong visible light efficiency. In this paper, two 2D/3D Ln-MOFs with different spatial configurations have been successfully synthesized under solvothermal conditions, namely [La(HL)(H2O)]n·3H2O (1), [Er(HL)·3/2(H2O)]n·3/2H2O (2), where H4L = 5-(bis(3-carboxybenzyl)amino)isophthalic acid. Their structures were determined by X-ray single crystal diffraction analysis, and further characterized by XRD analysis and IR spectroscopy. The complex 1 shows layered structure, which extends into a three-dimensional (3D) supramolecular network by π-π interactions, the complex 2 exhibit 3D network structures with a Schläfli symbol of 412·63 topologies, respectively. BET test results showed that there were carboxylic acid groups without coordination in the structure of complex 1, with abundant active sites and higher adsorption activity than complex 2, which would promote the effective contact and reaction between the photocatalyst and tetracycline (TC), thus improving the photocatalytic efficiency of complex 1. Under visible light irradiation, complex 1 showed good photocatalytic degradation of TC, and the degradation rate of TC could reach 75.54% under 120 min. This can be attributed to the effective separation of photogenerated electron-hole pairs and adsorption properties of complex 1. This study provides a new idea for MOFs as an efficient photocatalyst to degrade antibiotic pollutants.

Role of different metal precursors based MOFs for boosting anti-corrosion performance of mild steel in acid media

Benefiting from their significant features such as large specific surface area, adjustable structure and function, regular pore arrangement, and abundant active sites, metal organic frameworks (MOFs) exhibit great application prospects as anti-corrosion materials. Herein, (M-BTC, M = Mn, Fe, and Co, and BTC = benzenetricarboxylate) was prepared under solvothermal conditions and used as a highly efficient inhibitor for the protection of mild steel. The microstructure and physicochemical properties of the compounds were determined by powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), N2-adsorption, and microscopic analysis. The addition of MOF-based corrosion inhibitors decreases the rate of mild steel surface corrosion in acidic media due to the formation of an adsorbed layer on the metal surface. The inhibition mechanisms obey the Langmuir adsorption isotherm. A Mn-MOF based corrosion inhibitor recorded an inhibition efficiency of 94.7% at 200 ppm. At the end, the future outlooks of prepared MOFs for corrosion protection are provided. We hope this work will illuminate the achievement of high-performing anticorrosion MOFs and offer new ideas for the development of MOF-based materials for future corrosion protection applications.

Homochiral boron imidazolate frameworks built from mixed Chiral and achiral ligands

Chiral metal-organic frameworks (MOFs) have been studied extensively because of the potential application. Based on the complexity of chiral structure, it is a great challenge to study the formation of novel chiral centers under self-assembly conditions. By mixing chiral and achiral ligands, five unusual homochiral BIFs materials were synthesized by using d-camphoric acid (D-H2cam) and KBH(mim)3 (mim = 2-methylimidazole) under solvothermal condition. The orientations of mim rings had been locked to a specific angle in these structures and freed tridentate BH(mim)3- ligands were separated into two enantiomers, S–BH(mim)3- and R–BH(mim)3-. BIF-123 and BIF-124 exhibited similar (3, 4)-connected pillared-layer chiral structures with a pair of opposite helical substructures. BIF-125, 126 and 127 exhibited a 4-connected chiral diamond structure, which incorporates the homochiral helical substructures containing only S–BH(mim)3- ligand. These homochiral BIFs showed high pore volume in gas adsorption measurements and good stability under different solvent environments. Furthermore, the obvious CD signals of BIF-126 proved the chirality of bulk samples.

Three Ca(II)-Dy(III) heterometallic coordination polymers with different topologies and different water clusters: Synthesis and properties

Three new heterometallic polymers [DyL4Ca2(H2O)2.5(C2H5OH)0.5]·Him·H2O (1), [Dy2L6Ca3(H2O)12]·6H2O (2) and [Dy0.67L2Ca(H2O)2]·4H2O (3) (H2L = 4-chloropyridine-2,6-dicarboxylic acid, im = imidazole) were prepared under solvothermal conditions. The single crystal determination showed that polymers 1 and 3 are two-dimensional structures and polymer 2 is three-dimensional structure. It was found that different types of water clusters were present in these three polymers. They exhibit different topologies with the topological symbols {43}2{46·66·83}, {42·6·123}2{42·6}2 and {63}, where polymer 2 is a new topological type. A series of characterizations, such as XRD, IR, TGA, and solid-state fluorescence, were carried out on these three crystalline materials. They all show characteristic emission spectra of Dy(III) ions. Their quantum yields Фtotal are 4.01% (1), 2.25% (2), 2.88% (3), respectively.

Magnetically Controlled 3D Cartilage Regeneration.

The cartilage regeneration field has not yet overcome the issue of effective "shaping": growing regenerated cartilage in the desired shape, and maintaining that shape, is problematic. This study reports on a new method of cartilage regeneration in which the cartilage is shaped in three dimensions. Since cartilage is composed only of cartilage cells and an abundant extracellular matrix with no blood circulation, once it is damaged, the lack of nutrient supply means that it is difficult to repair. Scaffold-free cell sheet technology plays an important role in cartilage regeneration, avoiding inflammation and immune response caused by scaffold materials. However, cartilage regenerated from the cell sheet needs to be sculpted and shaped before it can be used for cartilage defect transplantation. In this study, we used a new ultra-strong magnetic-responsive Fe3O4 nanoparticle (MNP) to shape the cartilage in vitro. Super-magnetic Fe3O4 microspheres are manufactured by co-assembling negatively charged Cetyltrimethylammonium bromide (CTAB) and positively charged Fe3+ under solvothermal conditions. The Fe3O4 MNPs are swallowed by chondrocytes, and the MNP-labeled chondrocytes are acted upon by the magnetic field. The predetermined magnetic force makes the tissues coalesce to form a multilayer cell sheet with a predetermined shape. The shaped cartilage tissue is regenerated in the transplanted body, and the nano magnetic control particles do not affect cell viability. The nanoparticles in this study improve the efficiency of cell interaction through super-magnetic modification, and to a certain extent change the way the cells absorb magnetic iron nanoparticles. This phenomenon allows a more orderly and compact alignment of the cartilage cell extracellular matrix, promotes ECM precipitation and cartilage tissue maturation, and improves the efficiency of cartilage regeneration. The magnetic bionic structure, which contains specific magnetic particle-labeled cells, is deposited layer by layer to generate a three-dimensional structure with repair function, and further induce the production of cartilage. This study describes a new method for the regeneration of tissue engineered cartilage which has broad application prospects in regenerative medicine.

Facile synthesis of a mixed matrix membrane based on PTA@MOF-199 nanoparticles with proton conductivity

Firstly, H3[P(W3O10)4]@MOF-199 nanoparticles (PTA@MOF-199) of uniform morphology, about 80-125 nm, were successfully synthesized by a simple one-step reaction under solvothermal conditions and then these as-prepared nanoparticles were incorporated into polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) with solution-cast technique to fabricate a series of proton-conducting mixed matrix membranes with different mass percentage of PTA@MOF-199. These membranes were characterized by XRD and FT-IR. Afterwards, the influence of the mass percentage of PTA@MOF-199 and temperature on the proton-conducting properties were evaluated. Our work confirmed that the polyoxometalate (POM) functionalized MOFs had great application potential as proton conductive materials and provided a basis for further studies on other POM@MOFs based proton-conducting membranes fabrication.

A highly hydrophilic hydrazone-linked covalent organic framework as a fluorescent multianalyte sensor for detection of Cu2+ and Hg2+ in aqueous solution

Heavy metal pollution is of great threat to public health and the environment, and an effective method to detect and remove toxic heavy ions from water is highly desirable. The emerging covalent organic frameworks (COFs) with well-defined pore structures and specific functional units provide an excellent platform for fluorescent sensing. The hydrazone-linked framework material SH-COF with excellent hydrophilicity and abundant chelating sites was synthesized by bottom-up strategy under solvothermal conditions. The resultant SH-COF with specific binding sites was proposed to detect and remove Cu2+ and Hg2+. The SH-COF also exhibited the characteristics of high selectivity, high sensitivity, a lower limit of detection (0.244 μM for Cu2+ and 0.239 μM for Hg2+), and real-time response. Furthermore, the highly selective interaction of Cu2+ or Hg2+ with SH-COF was confirmed by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectra. A proposed sensing mechanism of COF for Cu2+ and Hg2+ was presented. This research also demonstrates the great potential of COFs in practical sensing applications.