RESUMEN

The search for new electrode materials for bipolar-supercapacitor performance is the intention of numerous research in the area of functional framework materials. Among various electrode materials, covalent triazine-based frameworks (CTFs) are in the spotlight drawing much attention as potential electrode material for energy storage. Herein, we present the synthesis of nitrogen-functionalized CTFs marked as CTF-Py-600 and CTF-Py-700 with high nitrogen content (18% and 14%, respectively) for supercapacitor application by applying 2,6-dicyanopyridine monomer via the polymerization reaction under ionothermal condition. The BET surface area of these materials are in the range of 940-1999 m2g-1. CTF-Py-700 demonstrates outstanding electrochemical performance in both potential windows. At the negative potential window, it exhibits a higher specific capacitance of 435 F g-1 (at 1 A g-1) compared to the positive potential window, where it shows a specific capacitance of 306 F g-1 (at 1 A g-1) owing to the synergistic existence of its large surface area (1999 m2g-1) and high nitrogen content (14%) with inherent microporosity. Remarkable cycling stability without noticeable degradation of specific capacitance after 15000 cycles was recorded for CTF-Py-700. This suggests that the nitrogen-functionalized CTFs are going to be a highly demanded electrode material for electrochemical energy storage applications.

RESUMEN

Wide applications of anhydrous rare-earth (RE) trichlorides RECl3 in organometallic chemistry, for the synthesis of optical and magnetic materials, and as catalysts require a facile approach for their synthesis. The known methods use or produce toxic substances, are complicated and have limited reliability and upscaling. It has been shown that task-specific ionic liquids (ILs) can dissolve many metal oxides without special reaction conditions at moderate temperature, making the metals accessible to downstream chemistry. Using imidazolium chloridoaluminate ILs, pure crystalline anhydrous RECl3 (RE=La-Nd, Sm-Dy) can be synthesized in one step from RE oxides in high yield. The Lewis acidic IL acts as solvent and reaction partner. The by-product [Al4 O2 Cl10 ]2- , which was detected spectroscopically, remains in solution. The reacted IL can be removed quantitatively by washing. ILs with various imidazolium cations and AlCl3 content and the effect of temperature and reaction time were tested.

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Phthalocyanines (PCs) are intriguing building blocks owing to their stability, physicochemical and catalytic properties. Although PC-based polymers have been reported before, many suffer from relatively low stability, crystallinity, and low surface areas. Utilizing a mixed-metal salt ionothermal approach, we report the synthesis of a series of metallophthalocyanine-based covalent organic frameworks (COFs) starting from 1,2,4,5-tetracyanobenzene and 2,3,6,7-tetracyanoanthracene to form the corresponding COFs named M-pPPCs and M-anPPCs, respectively. The obtained COFs followed the Irving-Williams series in their metal contents, surface areas, and pore volume and featured excellent CO2 uptake capacities up to 7.6 mmol g-1 at 273 K, 1.1 bar. We also investigated the growth of the Co-pPPC and Co-anPPC on a highly conductive carbon nanofiber and demonstrated their high catalytic activity in the electrochemical CO2 reduction, which showed Faradaic efficiencies towards CO up to 74 % at -0.64 V vs. RHE.

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A novel layered magnesium phosphate (MgP) was synthesised from a MgO-P2 O5 -choline chloride-oxalic acid dihydrate system using an ionothermal approach. Single crystal samples of MgP were obtained following introduction of diethylamine (DEA) to the reaction system. Its structure revealed that both the layer and the sheets contained Mg octahedra. Interestingly, adding the layered material to lithium grease resulted in superior lubrication with higher load-carrying, anti-wear and friction reduction capacities compared with the typical lubricant MoS2 ; the PB value of base grease was increased from 353 to 1078 and 549 N, the wear scar diameter was decreased from 0.50 to 0.34 and 0.46 mm, and the friction coefficient was decreased from 0.082 to 0.056 and 0.075, respectively. We also discuss the lubrication mechanism of layered materials based on the crystal structure and resource endowment. The findings could assist the development of new high-efficiency solid lubricants.

RESUMEN

Organic positive electrodes featuring lightweight and tunable energy storage modes by molecular structure engineering have promising application prospects in dual-ion batteries. Herein, a series of highly porous covalent triazine frameworks (CTFs) were synthesized under ionothermal conditions using fluorinated aromatic nitrile monomers containing a piperazine ring. Fluorinated monomers can result in more defects in CTFs, leading to a higher surface area up to 2515 m2 g-1 and a higher N content of 11.34 wt % compared to the products from the non-fluorinated monomer. The high surface area and abundant redox sites of these CTFs afforded high specific capacities (up to 279 mAh g-1 at 0.1 A g-1 ), excellent rate performance (89 mAh g-1 at 5 A g-1 ), and durable cycling performance (92.3 % retention rate after 500 cycles at 2.0 A g-1 ) as dual-ion positive electrodes.

RESUMEN

Semiconducting carbon nitride polymers are used in metal-free photocatalysts and in opto-electronic devices. Conventionally, they are obtained using thermal and ionothermal syntheses in inscrutable, closed systems and therefore, their condensation behavior is poorly understood. Here, the synthetic protocols and properties are compared for two types of carbon nitride materials - 2D layered poly(triazine imide) (PTI) and hydrogen-bonded melem hydrate - obtained from three low-melting salt eutectics taken from the systematic series of the alkali metal halides: LiCl/KCl, LiBr/KBr, and LiI/KI. The size of the anion plays a significant role in the formation process of the condensed carbon nitride polymers, and it suggests a strong templating effect. The smaller anions (chloride and bromide) become incorporated into triazine (C3 N3 )-based PTI frameworks. The larger iodide does not stabilize the formation of a triazine-based polymer, but instead it leads to the formation of the heptazine (C6 N7 )-based hydrogen-bonded melem hydrate as the main crystalline phase. Melem hydrate, obtained as single-crystalline powders, was compared with PTI in photocatalytic hydrogen evolution from water and in an OLED device. Further, the emergence of each carbon nitride species from its corresponding salt eutectic was rationalized via density functional theory calculations. This study highlights the possibilities to further tailor the properties of eutectic salt melts for ionothermal synthesis of organic functional materials.

RESUMEN

Covalent triazine-based frameworks (CTFs) are typically produced by the salt-melt polycondensation of aromatic nitriles in the presence of ZnCl2 . In this reaction, molten ZnCl2 salt acts as both a solvent and Lewis acid catalyst. However, when cyclotrimerization takes place at temperatures above 300 °C, undesired carbonization occurs. In this study, an ionothermal synthesis method for CTF-based photocatalysts was developed using a ternary NaCl-KCl-ZnCl2 eutectic salt (ES) mixture with a melting point of approximately 200 °C. This temperature is lower than the melting point of pure ZnCl2 (318 °C), thus providing milder salt-melt conditions. These conditions facilitated the polycondensation process, while avoiding carbonization of the polymeric backbone. The resulting CTF-ES200 exhibited enhanced optical and electronic properties, and displayed remarkable photocatalytic performance in the hydrogen evolution reaction.

RESUMEN

Poly(triazine imide) (PTI) is a highly crystalline semiconductor, and though no techniques exist that enable synthesis of macroscopic monolayers of PTI, it is possible to study it in thin layer device applications that are compatible with its polycrystalline, nanoscale morphology. We find that the by-product of conventional PTI synthesis is a C-C carbon-rich phase that is detrimental for charge transport and photoluminescence. An optimized synthetic protocol yields a PTI material with an increased quantum yield, enabled photocurrent and electroluminescence. We report that protonation of the PTI structure happens preferentially at the pyridinic N atoms of the triazine rings, is accompanied by exfoliation of PTI layers, and contributes to increases in quantum yield and exciton lifetimes. This study describes structure-property relationships in PTI that link the nature of defects, their formation, and how to avoid them with the optical and electronic performance of PTI. On the basis of our findings, we create an OLED prototype with PTI as the active, metal-free material.

RESUMEN

Bi2 S3 was dissolved in the presence of NaCl in the ionic liquid [BMIm]Cl ⋅ 4AlCl3 (BMIm=1-n-butyl-3-methylimidazolium) through annealing the mixture at 180 °C. Upon cooling to room temperature, orange, air-sensitive crystals of Na(Bi7 S8 )[S(AlCl3 )3 ]2 [AlCl4 ]2 (1) precipitated. X-ray diffraction on single-crystals of 1 revealed a triclinic crystal structure that contains (Bi7 S8 )5+ spiro-dicubanes, [S(AlCl3 )3 ]2- tetrahedra triples, isolated [AlCl4 ]- tetrahedra, and sodium cations.

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Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) in specific molar ratios. Since their first appearance in the literature in 2003, they have shown a wide range of applications, ranging from the selective extraction of biomass or metals to medicine, as well as from pollution control systems to catalytic active solvents and co-solvents. The very peculiar physical properties of DESs, such as the elevated density and viscosity, reduced conductivity, improved solvent ability and a peculiar optical behavior, can be exploited for engineering modular systems which cannot be obtained with other non-eutectic mixtures. In the present review, selected DESs research fields, as their use in materials synthesis, as solvents for volatile organic compounds, as ingredients in pharmaceutical formulations and as active solvents and cosolvents in organic synthesis, are reported and discussed in terms of application and future perspectives.

RESUMEN

The use of reactive molten salts, i.e., ZnCl2, as a soft template and a catalyst has been actively investigated in the preparation of covalent triazine frameworks (CTFs). Although the soft templating effect of the salt melt is more prominent at low temperatures, close to the melting point of ZnCl2, leading to the formation of abundant micropores, a significant mesopore formation is observed that is due to the partial carbonization and other side reactions at higher temperatures (>400 °C). Evidently, high-temperature synthesis of CTFs in various eutectic salt mixtures of ZnCl2 with alkali metal chloride salts also leads to mesopore formation. We reasoned that using the isocyanate moieties instead of cyano groups in the monomer, 1,4-phenylene isocyanate, could enable efficient interactions between carbonyl moieties and alkali metal ions to realize efficient salt templating to form covalent isocyanurate frameworks (CICFs). In this direction, the trimerization of 1,4-phenylene diisocyanate was carried out under ionothermal conditions at different reaction temperatures using ZnCl2 (CICF) and the eutectic salt mixture of KCl/NaCl/ZnCl2 (CICF-KCl/NaCl) as the reactive solvents. We observed notable differences in the morphologies of the two polymers, whereas CICF showed irregular-shaped micrometer-sized particles, the CICF-KCl/NaCl exhibited a filmlike morphology. Moreover, favorable ion-dipole interactions between alkali metal cations and oxygen atoms of the monomer facilitated two-dimensional growth and the formation of a purely microporous framework in the case of CICF-KCl/NaCl along with a near theoretical retention of the nitrogen content at 500 °C. The CICF-KCl/NaCl showed a BET surface area of 590 m2 g-1 along with a CO2 uptake capacity of 5.9 mmol g-1 at 273 K and 1.1 bar because of its high microporosity and nitrogen content. On the contrary, in the absence of alkali metal ions, CICF showed high mesopore content and a moderate CO2 uptake capacity. This study underscores the importance of the strength of the interactions between the salts and the monomer in the ionothermal synthesis to control the morphology, porosity, and gas uptake properties of the porous organic polymers.

RESUMEN

Hierarchical AlPO-34 molecular sieves microspheres were synthesized in a [BMIm]Br ionic liquid without template or complex post-treatment process. The formation mechanism of such framework structures and their morphology were investigated. [BMIm]Br was proven to serve as both solvent and sole provider of the structure directing agent. The organic amine in the compound affects the framework density of the crystals and promotes the formation of a chabazite (CHA) type framework. After ageing for 1 h the AlPO-34 microspheres are formed due to the aggregation properties of the ionic liquid. The hierarchical mirosphere has a relatively high Brunauer-Emmett-Teller surface area and a considerably uniform mesoporous channel network. The hierarchical AlPO-34 microspheres were used as absorbers of heavy metal cations and showed a higher loading capacity and distribution coefficient compared with the AlPO-34-NH.

RESUMEN

Ionic liquids and deep eutectic solvents are of growing interest as solvents for the resource-efficient synthesis of inorganic materials. This Review covers chemical reactions of various deep eutectic solvents and types of ionic liquids, including metal-containing ionic liquids, [BF4 ]- - or [PF6 ]- -based ionic liquids, basic ionic liquids, and chalcogen-containing ionic liquids. Cases in which cations, anions, or both are incorporated into the final products are also included. The purpose of this Review is to raise caution about the chemical reactivity of ionic liquids and deep eutectic solvents and to establish a guide for their proper use.

RESUMEN

Two types of layered sulfido stannates or a molecular cluster compound are obtained upon ionothermal treatment of the simple sulfido stannate salt K4 [SnS4 ] · 4H2 O that is based on binary tetrahedral [SnS4 ]4- anions. The formation of the respective products, novel compounds (C4 C1 C1 Im)2 [Sn3 S7 ] (1 a), (C4 C1 C2 Im)2 [Sn3 S7 ] (1 b), and (C4 C1 C2 Im)2 [Sn4 S9 ] (2) with layered anionic substructures, or the recently reported compound (C4 C1 C1 Im)4+x [Sn10 O4 S16 (SMe)4 ][An]x (A) comprising a molecular cluster anion, is controlled by both the choice of the ionic liquid cation and the reaction temperature. We report the scale-up of the syntheses by a factor of 100 with regard to other reported ionothermal syntheses of related compounds, and a procedure of how to isolate them in phase-pure form - both being rare observations in chalcogenido stannate chemistry in ionic liquids. Moreover, the synthesis of compound 1 a can be achieved by rapid cation exchange starting out from 1 b, which has not been reported for organic cations in any chalcogenido stannate salt to date.

RESUMEN

Bi2 S3 was dissolved in the presence of either AuCl/PtCl2 or AgCl in the ionic liquids [BMIm]Cl ⋅ xAlCl3 (BMIm=1-n-butyl-3-methylimidazolium; x=4-4.3) through annealing the mixtures at 180 or 200 °C. Upon cooling to room temperature, orange, air-sensitive crystals of [BMIm](Bi4 S4 )[AlCl4 ]5 (1) or Ag(Bi7 S8 )[S(AlCl3 )3 ]2 [AlCl4 ]2 (2) precipitated, respectively. 1 did not form in the absence of AuCl/PtCl2 , suggesting an essential role of the metal cations. X-ray diffraction on single-crystals of 1 revealed a monoclinic crystal structure that contains (Bi4 S4 )4+ heterocubanes and [AlCl4 ]- tetrahedra as well as [BMIm]+ cations. The intercalation of the ionic liquid was confirmed via solid state NMR spectroscopy, revealing unusual coupling behavior. The crystal structure of 2 consists of (Bi7 S8 )5+ spiro-dicubanes, [S(AlCl3 )3 ]2- tetrahedra triples, isolated [AlCl4 ]- tetrahedra, and heavily disordered silver(I) cations. No cation ordering took place in 2 upon slow cooling to 100 K.

RESUMEN

Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this work, ionothermally synthesized Cu-doped Fe3O4 magnetic nanoparticles (Cu-Fe3O4 MNPs) were found to be a highly efficient heterogeneous Fenton-like catalyst for complete decolorization of the RhB solution with H2O2 at pH ~ 7 and 25 °C. The effects of the catalyst loading, initial concentrations of RhB and H2O2, co-existing natural organic matter and inorganic salts, reaction temperature, and radical scavengers on the catalytic performance of Cu-Fe3O4 were investigated. Monte-Carlo simulations revealed that copper dopants facilitated the activation of H2O2 via adopting a terminal end-on adsorption mode and increased collision frequency by bringing the RhB molecules closer to H2O2 and the magnetite surface. These theoretical calculations provide new insight into the promotional effect of copper dopants in magnetite at molecular level.

Asunto(s)

RESUMEN

Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time-consuming process and restricted to well-soluble precursor molecules. Synthesis of polyimide-linked COFs (PI-COFs) is further complicated by the poor reversibility of the ring-closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI-COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene-based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high-temperature XRPD analysis hints to the formation of precursor-salt adducts as crystalline intermediates, which then react with each other to form the COF.

RESUMEN

Optically nonlinear Pb2 B5 O9 X (X = Cl, Br) borate halides are an important group of materials for second harmonic generation (SHG). Additionally, they also possess excellent photocatalytic activity and stability in the process of dechlorination of chlorophenols, which are typical persistent organic pollutants. It would be of great interest to conduct in situ (photo-) catalysis investigations during the whole photocatalytic process by SHG when considering them as photocatalytic materials. In order to get superior photocatalytic efficiency and maximum surface information, small particles are highly desired. Here, a low-cost and fast synthesis route that allows growing microcrystalline optically nonlinear Pb2 B5 O9 X borate halides at large quantities is introduced. When applying the ionothermal growth process at temperatures between 130 and 170 °C, microcrystallites with an average size of about 1 µm precipitate with an orthorhombic hilgardite-like borate halide structure. Thorough examinations using powder X-ray diffraction and scanning electron microscopy, the Pb2 B5 O9 X microcrystals are indicated to be chemically pure and single-phased. Besides, the Pb2 B5 O9 X borate halides' SHG efficiencies are confirmed using confocal SHG microscopy. The low-temperature synthesis route thus makes these borate halides a highly desirable material for surface studies such as monitoring chemical reactions with picosecond time resolution and in situ (photo-) catalysis investigations.

RESUMEN

The title salt, (PMIM)2[Ni(P2S8)2] (PMIM = 3-methyl-1-propyl-1H-imidazol-3-ium, C7H13N2 +), consists of a nickel-thio-phosphate anion charge-balanced by a pair of crystallographically independent PMIM cations. It crystallizes in the monoclinic space group P21/n. The structure exhibits the known [Ni(P2S8)2]2- anion with two unique imidazolium cations in the asymmetric unit. Whereas one PMIM cation is well ordered, the other is disordered over two orientations with refined occupancies of 0.798 (2) and 0.202 (2). The salt was prepared directly from the elements in the ionic liquid [PMIM]CF3SO3. Whereas one of the PMIM cations is well behaved (it does not exhibit disorder even in the propyl side chain), the other is found in two overlapping positions. The refined occupancies for the two orientations are roughly 80:20. Here, too, there appears to be little disorder in the propyl arm.

RESUMEN

After crystallization during ionothermal syntheses in phospho-nium-containing ionic liquids, the structure of (NH4)3Al2(PO4)3 [tri-ammonium dialuminum tris-(phosphate)] was refined on the basis of powder X-ray diffraction data from a synchrotron source. (NH4)3Al2(PO4)3 is a member of the structural family with formula A 3Al2(PO4)3, where A is a group 1 element, and of which the NH4, K, and Rb forms were previously known. The NH4 form is isostructural with the K form, and was previously solved from single-crystal X-ray data when the material (SIZ-2) crystallized from a choline-containing eutectic mixture [Cooper et al. (2004 ▸). Nature, 430, 1012-1017]. Our independent refinement incorporates NH4 groups and shows that these NH4 groups are hydrogen bonded to framework O atoms present in rings containing 12 T sites in a channel along the c-axis direction. We describe structural details of (NH4)3Al2(PO4)3 and discuss differences with respect to isostructural forms.