One-pot synthesis of poly(ionic liquid)s with 1,2,3-triazolium-based backbones via clickable ionic liquid monomers

Clickable α-azide-ω-alkyne ionic liquid monomers were developed and subsequently applied to the one-pot synthesis of ionically conducting poly(ionic liquid)s with 1,2,3-triazolium-based backbones through a click chemistry strategy. This approach does not require the use of solvents, polymerisation mediators, or catalysts. The obtained poly(ionic liquid)s were characterized by NMR, differential scanning calorimetry, thermogravimetric analysis, and impedance spectroscopy analysis. Moreover, these poly(ionic liquid)s were cross-linked via N-alkylation with a dianion quarternizing agent to achieve enhanced ionic conductivity and mechanical strength. The resulting free-standing films showed a Young''s modulus up to 4.8 MPa and ionic conductivities up to 4.60 × 10⁻⁸ S cm⁻¹ at 30 °C. This facile synthetic strategy has the potential to expand the availability of poly(ionic liquid)s and promote the development of functional materials.

Clickable ionic liquid monomers realize the one-pot synthesis of ionically conducting poly(ionic liquid)s with 1,2,3-triazolium-based backbones via click chemistry.     

Cross-linked poly(ionic liquid) as precursors for nitrogen-doped porous carbons

A soluble and easily dispersive cross-linked poly(ionic liquid), copolymer of 1-vinyl-3-butylimidazolium bromide ([VBIM][Br]) and divinylbenzene (DVB), was used as a precursor for nitrogen doped porous carbons (NPCs) with SiO₂ (from tetraethyl orthosilicate) as a template. The NPCs were characterized by infrared (IR) spectroscopy, nitrogen adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermo gravimetric analysis (TGA), elemental analysis and X-ray photoelectron spectroscopy (XPS). The specific surface area and porosity of NPCs depended on the carbonization temperature, the SiO₂/[VBIM][Br] ratio and the precursors. Under the optimized conditions, the NPC prepared from cross-linked poly(ionic liquid), P([VBIM][Br]–0.1DVB), gave a high specific surface area up to 1324 m² g⁻¹. XRD indicated that amorphous and disordered graphitic layers were dominant in NPCs. The nitrogen content was about 4–5 wt% in NPCs, and the nitrogen bonding state observed using XPS analysis was mainly pyridinic- and pyrrolic-N. Meanwhile, the cyclic voltammetry, gravimetric charge–discharge curves and electrochemical impedance spectroscopy of the NPCs were also investigated, the specific capacitance was up to 243 F g⁻¹ at 0.1 A g⁻¹, and the retention ratio was nearly 100% after charge–discharge cycling 2400 times at 2 A g⁻¹ in 6 M KOH electrolyte.

The cross-linked PIL with “network structure” can fabricate nitrogen-doped porous carbons with higher specific surface area.     

Tris-imidazolinium-based porous poly(ionic liquid)s as an efficient catalyst for decarboxylation of cyclic carbonate to epoxide

A series of imidazolinium-based porous poly(ionic liquid)s (PILs) with different anions prepared by free-radical copolymerization of an arene-bridged tris-vinylimidazolium salt and divinylbenzene (DVB) were constructed. The as-prepared PILs were characterized by BET, SEM, TEM, TGA and Elemental Analysis (EA), and the results showed that they had plentiful ionic sites, and abundant and stable mesopores. In particular, the density of ionic sites and pore structure of PILs could be controlled by adjusting the content of DVB. Moreover, the PILs were used as efficient heterogeneous catalysts for the decarboxylation of cyclic carbonates to epoxides for the first time. Results showed that the catalytic activity of PILs was positively correlated with the nucleophilicity of the anions in PILs, and PDVB-[PhTVIM]Cl-1 with a chloride anion-enriched skeleton displayed the best catalytic performance. Without any solvent or cocatalyst, PDVB-[PhTVIM]Cl-1 achieved a TOF value of 108.1 h⁻¹ and the yield of butylene oxide of 89.6%, which was even better than the homogeneous IL-based catalysts (TOF value: 8.7 h⁻¹) that had been previously reported. Meanwhile, PDVB-[PhTVIM]Cl-1 also exhibited excellent recyclability and substrate compatibility.

The tris-imidazolium-based porous poly(ionic liquid)s with plentiful ionic sites prepared by free-radical polymerization exhibited superior catalytic performance toward the heterogeneous conversion of butylene carbonate to butylene oxide.     

Self-standing cellulose nanofiber/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)/ionic liquid actuators with superior performance

This paper describes new actuators with cellulose nanofiber/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)/ionic liquid (CNF/PEDOT:PSS/IL) structures. Devices containing these structures exhibit higher strain and maximum generated stress than those based on only PEDOT:PSS/IL. The new actuator system contains an electrode, which is an electrochemical capacitor, and which consists of both a faradaic capacitor (FC) and a small electric double-layer capacitor (EDLC), i.e., PEDOT:PSS. This combined capacitor plays the role of an FC and a base polymer, and the CNF skeleton is used in the place of carbon nanotubes (CNTs). This device therefore functions differently from traditional CNT/PVdF–HFP/IL actuators, which are only used as EDLC units and from PEDOT:PSS/vapor-grown carbon nanofibers (VGCF)/IL actuators, which are used as hybrid (FC and EDLC) units. The developed films are novel, robust, and flexible, and demonstrate potential as actuator materials for wearable energy-conversion devices. A double-layer charging kinetic model, which is similar to that previously proposed for PEDOT:PSS/CNT/IL actuators, is developed to explain the oxidation and reduction of PEDOT:PSS. This model successfully simulates the frequency-dependent displacement response of actuators.

This paper describes new actuators with cellulose nanofiber/PEDOT:PSS/ionic liquid (CNF/PEDOT:PSS/IL) structures. These devices show superior performance with respect to strain and maximum generated stress compared to those containing PEDOT:PSS/IL.     

The effect of the morpholinium ionic liquid anion on the catalytic activity of Rh (or Pt) complex–ionic liquid systems in hydrosilylation processes

Studies were performed on the catalytic activity for olefin hydrosilylation shown by three rhodium complexes, [{Rh(μ-OSiMe₃)(cod)}₂] (I), [{Rh(μ-Cl)(cod)}₂] (II) and [RhCl(PPh₃)₃] (III), and three platinum complexes, [Pt(PPh₃)₄] (IV), [Pt(PPh₃)₂Cl₂] (V) and PtCl₄ (VI), immobilized in a series of different anion-containing morpholinium ionic liquids. The effect of the kind of anion (its nucleophilic character) on the activity, stability and possibility of a catalytic system with multiple uses in the hydrosilylation process has been established. In the case of the best systems it was possible to reuse the same catalyst sample 10 times almost without any decrease in the activity and a TON value over 99 000 was obtained.

Rhodium and platinum complexes were immobilized in morpholinium ionic liquids, the effect of which on the catalytic activity was determined.     

Fe3O4@SiO2 nanoparticle supported ionic liquid for green synthesis of antibacterially active 1-carbamoyl-1-phenylureas in water

In the present work, we have designed a novel, heterogeneous and recyclable magnetic Brønsted acidic ionic liquid based on 5-phenyl-1H-tetrazole. The {Fe₃O₄@SiO₂@(CH₂)₃5-phenyl-1H-tetrazole-SO₃H/Cl} ([FSTet-SO₃H]Cl) was prepared via the immobilization of 5-phenyl-1H-tetrazole-bonded sulfonic acid onto the surface of silica-coated magnetic nanoparticles using 3-chloropropyltriethoxysilane as a linker. The catalyst was characterized by XRD, TEM, FESEM, EDS, TG-DTA, and FT-IR. The ability and high activity of this catalyst were demonstrated in the synthesis of 1-carbamoyl-1-phenylureas with good to excellent yields via a new, simple and one-pot procedure in aqueous media under reflux conditions. This procedure has advantages such as high yields, short reaction times, a simple methodology and work-up process, green reaction conditions, high stability, catalytic activity, and easy preparation, separation and reusability of the catalyst. The synthesis of these compounds was confirmed by FT-IR, ¹H NMR, ¹³C NMR and CHN. In addition, we investigated the biological properties of the 1-carbamoyl-1-phenylureas as newly synthesized compounds. The described catalyst could be easily separated from the reaction mixture by additional magnetic force and reused several times without a remarkable loss of its catalytic activity and any considerable changes in the product yield and the reaction time.

We have developed a novel and green method for the synthesis of antibacterially active 1-carbamoyl-1-phenylureas in water using {Fe₃O₄@SiO₂@(CH₂)₃5-phenyl-1H-tetrazole-SO₃H/Cl} ([FSTet-SO₃H]Cl) as a recyclable magnetic catalyst.     

The effects of different inorganic salts on the structure and properties of ionic liquid plasticized starch/poly(butylene succinate) blends

1-Butyl-3-methylimidazole chloride ([BMIM]Cl) plasticized starch/poly(butylene succinate) (PBS) blends containing inorganic salts with different cations were prepared by a Haake mixer. The compatibility, thermal behaviors including crystallinity, crystallization temperature and melting temperature, thermal stability, and mechanical properties of these blends were systematically investigated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results showed that the inorganic salts could interact strongly with [BMIM]Cl plasticized starch/PBS blends to improve their mechanical properties, while the thermal stability of the [BMIM]Cl plasticized starch/PBS blends was simultaneously reduced. The SEM results suggested that the compatibility of [BMIM]Cl plasticized starch and PBS was significantly improved with increasing inorganic salt content. Furthermore, by incorporating inorganic salts, the melting enthalpy (ΔH_m), crystallinity (X_c), and cold crystallization temperature (T_cc) of the blends were decreased.

1-Butyl-3-methylimidazole chloride ([BMIM]Cl) plasticized starch/poly(butylene succinate) (PBS) blends containing inorganic salts with different cations were prepared by a Haake mixer.     

Synthesis of poly(ionic liquid) for trifunctional epoxy resin with simultaneously enhancing the toughness,thermal and dielectric performances

Poly(ionic liquid) (PIL), integrating the characteristics of both polymers and ionic liquid, is synthesized and employed to modify diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate (TDE-85). With the addition of PIL, the fracture toughness, and thermal and dielectric performances of TDE-85 were discovered to be simultaneously improved, meanwhile the tensile modulus and strength is increased. Upon an optimal loading of 3 wt% PIL, the critical stress intensity factor (K_IC), tensile modulus and strength are raised by 92.9%, 13.3% and 10.7%, respectively. Multi-toughening mechanisms due to spherical domains of PIL formed in TDE-85 during curing are responsible for the improved toughness. Moreover, the dielectric and thermal properties of TDE-85 are also enhanced by adding PIL. With the optimal addition of 5 wt% PIL, the dielectric constant of the composites is enhanced by 62.5%, the glass transition temperature is increased by 16.58 °C and the residual weight of carbon is increased by 59%.

This work will provide a strategy to obtain epoxy with relatively high toughness, thermal and dielectric properties.     

Realizing outstanding electrochemical performance with Na3V2(PO4)2F3 modified with an ionic liquid for sodium-ion batteries

Na₃V₂(PO₄)₂F₃ is a typical NASICON structure with a high voltage plateau and capacity. Nevertheless, its applications are limited due to its low conductivity and poor rate performance. In this study, nitrogen–boron co-doped carbon-coated Na₃V₂(PO₄)₂F₃ (NVPF-CNB) was prepared by a simple sol–gel method using an ionic liquid (1-vinyl-3-methyl imidazole tetrafluoroborate) as a source of nitrogen and boron for the first time. The morphology and electrochemical properties of NVPF-CNB composites were investigated. The results show that a nitrogen–boron co-doped carbon layer could increase the electron and ion diffusion rate, reduce internal resistance, and help alleviate particle agglomeration. NVPF-CNB-30 exhibited better rate performance under 5C and 10C charge/discharge with initial reversible capacities of 99 and 90 mA h g⁻¹, respectively. Furthermore, NVPF-CNB-30 illustrates excellent cyclic performance with the capacity retention rate reaching 91.9% after 500 cycles at 5C, as well as a capacity retention rate of about 95.5% after 730 cycles at 10C. The evolution of the material''s structure during charge/discharge processes studied by in situ X-ray diffraction confirms the stable structure of nitrogen–boron co-doped carbon-coated Na₃V₂(PO₄)₂F₃. Co-doping of nitrogen and boron also provides more active sites on the surface of Na₃V₂(PO₄)₂F₃, revealing a new strategy for the modification of sodium-ion batteries.

An ionic liquid is used as a new nitrogen and boron source to synthesize nitrogen–boron co-doped carbon-coated Na₃V₂(PO₄)₂F₃ (NVPF-CNB).     

A novel reaction mechanism for the synthesis of coconut oil-derived biopolyol for rigid poly(urethane-urea) hybrid foam application

Coconut oil (CO) has become one of the most important renewable raw materials for polyol synthesis due to its abundance and low price. However, the saturated chemical structure of CO limits its capability for functionalization. In this study, a novel reaction mechanism via the sequential glycerolysis and amidation of CO triglycerides produced an amine-based polyol (p-CDEA). The synthesized biopolyol has a relatively higher hydroxyl value of 361 mg KOH per g relative to previously reported CO-based polyols with values ranging from 270–333 mg KOH per g. This primary hydroxyl-rich p-CDEA was used directly as a sole B-side polyol component in a polyurethane-forming reaction, without further purification. Results showed that a high-performance poly(urethane-urea) (PUA) hybrid foam was successfully produced. It has a compressive strength of 226 kPa and thermal conductivity of 23.2 mW (m⁻¹ K⁻¹), classified as type 1 for a rigid structural sandwich panel core and type 2 for rigid thermal insulation foam applications according to ASTM standards. Fourier-transform infrared (FTIR) spectroscopy was performed to characterize the chemical features of the polyols and foams. Scanning electron microscopy (SEM) analysis was also performed to evaluate the morphological structures of the synthesized foams. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to investigate the foam''s thermal characteristics. Thus far, this work is the first to report a novel and effective reaction mechanism for the synthesis of a highly functional CO-derived polyol and the first CO-based polyol with no petroleum-based replacement that may serve as raw material for rigid PUA foam production. PUA hybrid foams are potential insulation and structural materials. This study further provided a compelling case for enhanced sustainability of p-CDEA PUA hybrid foam against petroleum-based polyurethane.

Synthesis of a coconut oil-based biopolyol via sequential glycerolysis and amidation; and its subsequent use as a sole polyol for rigid poly(urethane-urea) hybrid foam production.     

An efficient approach for the green synthesis of biologically active 2,3-dihydroquinazolin-4(1H)-ones using a magnetic EDTA coated copper based nanocomposite

2,3-Dihydroquinazolinone derivatives are known for antiviral, antimicrobial, analgesic, anti-inflammatory, and anticancer activities. However, recent approaches used for their synthesis suffer from various drawbacks. Therefore, we have fabricated a highly efficient magnetic EDTA-coated catalyst, Fe₃O₄@EDTA/CuI via a simple approach. The ethylenediamine tetraacetic acid (EDTA) plays a crucial role by strongly trapping the catalytic sites of CuI nanoparticles on the surface of the Fe₃O₄ core. The designed nanocatalyst demonstrates its potential for the catalytic synthesis of 2,3-dihydroquinazolinones using 2-aminobenzamide with aldehydes as the reaction partners. The nanocatalyst was thoroughly characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma analysis (ICP). The physiochemically characterized nanocatalyst was tested for synthesis of 2,3-dihydroquinazolinones and higher yields of derivatives were obtained with less time duration. Moreover, the catalytic synthesis is easy to operate without the use of any kind of additives/bases. Furthermore, the catalyst was magnetically recoverable after the completion of the reaction and displayed reusability for six successive rounds without any loss in its catalytic efficiency (confirmed by XRD, SEM, and TEM of the recycled material) along with very low leaching of copper (2.12 ppm) and iron (0.06 ppm) ions. Also, the green metrics were found in correlation with the ideal values (such as E factor (0.10), process mass intensity (1.10), carbon efficiency (96%) and reaction mass efficiency (90.62%)).

The fabricated catalyst Fe₃O₄@EDTA/CuI facilitates the synthesis of 2,3-dihydroquinazolin-4(1H)-ones under sustainable conditions with ideal values of green metrics in a short reaction time.     

Influence of poly(lactide) stereocomplexes as nucleating agents on the crystallization behavior of poly(lactide)s

The influence of the addition of linear and four-arm poly(lactide) (PLA) stereocomplexes (scPLAs) on the non-isothermal and isothermal crystallization behavior of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) from the molten state was investigated. The linear PLAs and four-arm PLA with a similar chain length for each arm were synthesized by ring-opening polymerization. The linear and four-arm scPLAs were then prepared by solution blending and characterized by ¹H-NMR, FTIR, and WAXD analysis. Various mass ratios of the scPLAs were subsequently added to PLLA and PDLA as nucleating agents and specimens were prepared by solution casting. The isothermal and non-isothermal crystallization behavior of the specimens was examined by differential scanning calorimetry and polarized optical microscopy. The SC crystallites effectively promoted the nucleation of the PLAs, thereby increasing the general crystallization rate of the matrix. A 10% content of stereocomplex nucleating agent increased the crystallization rate of PDLA and PLLA by more than 55% and 70%, respectively. Compared with the linear scPLA, the four-arm scPLA more strongly promoted crystallization at higher temperatures. This might be because the greater degree of branching and larger steric hindrance of the four-arm scPLA led to the formation of defective SC crystallites, which was more beneficial for adsorption of the matrix on the crystal surface and permitted the nucleation and growth at higher temperatures. These results demonstrate that scPLAs can potentially be used as nucleating agents to improve the performance and transparency of PLA films.

The influence of the addition of linear and four-arm poly(lactide) stereocomplexes on the crystallization behavior of poly(l-lactide) and poly(d-lactide) from the molten state was investigated.     

Urazolium diacetate as a new,efficient and reusable Brønsted acid ionic liquid for the synthesis of novel derivatives of thiazolidine-4-ones

Urazolium diacetate catalyzed synthesis of new derivatives of 1,3-thiazolidine-4-ones (azo dispersive dyes family) via multicomponent reaction of various aldehydes, thioglycolic acid and 4-aminoazobenzene under solvent-free reaction was reported. This avenue for the synthesis of new derivatives of thiazolidine-4-one has advantages as: short reaction times, high yields, green aspect of chemistry and environmental friendliness, easy workup, solvent-free conditions and convenient operation.

Urazolium diacetate catalyzed synthesis of new derivatives of 1,3-thiazolidine-4-ones (azo dispersive dyes family) via multicomponent reaction of various aldehydes, thioglycolic acid and 4-aminoazobenzene under solvent-free reaction was reported.     

Triazine bis(pyridinium) hydrogen sulfate ionic liquid immobillized on functionalized halloysite nanotubes as an efficient catalyst for one-pot synthesis of naphthopyranopyrimidines

1,1′-(6-(Propyl amino)-1,3,5-triazine-2,4-diyl)bis(pyridinium) hydrogen sulfate immobillized on halloysite nanotubes [(PATDBP)(HSO₄)₂@HNT] as a solid acid nanocatalyst was successfully synthesized and characterized by various analysis techniques such as FT-IR, TGA, SEM/EDX, elemental mapping, TEM and elemental analysis. This catalyst was found to be highly efficient for the convenient synthesis of naphthopyranopyrimidine derivatives through a one-pot three-component reaction of β-naphthol, aldehydes and N,N-dimethylbarbituric acid in excellent yields under solvent-free conditions. Furthermore, the catalyst could be recovered and reused five times without any notable loss of its activity.

A novel method for synthesis of naphthopyranopyrimidines, using [(PATDBP)(HSO₄)₂@HNT] as a green and reusable catalyst is reported.     

Multiple actions of poly(ethylene octene) grafted with glycidyl methacrylate on the performance of poly(lactic acid)

Poly(ethylene octene) grafted with glycidyl methacrylate (POE-g-GMA) was employed to improve the rheological and thermal properties, toughness, and foaming behaviors of poly(lactic acid) (PLA) through a chain extension effect. The dynamic rheological properties of PLA were improved significantly with increasing content of POE-g-GMA, due to the chain extension reaction between PLA and POE-g-GMA. As the content of POE-g-GMA increased, the cold crystallization temperature of PLA decreased by more than 10 °C and the crystallinity of PLA increased slightly from 1.2% to 4.7%, respectively. The impact strength of PLA with a POE-g-GMA content of 10 wt% increased by more than 4 times, compared with that of pure PLA. A sea-island structure could be observed in the PLA/POE-g-GMA blends and the distribution of POE-g-GMA was uniform. PLA foams with various POE-g-GMA contents were prepared in a stainless-steel autoclave using supercritical CO₂ as a physical blowing agent. The cellular morphology of PLA foam was obviously improved when the concentration of POE-g-GMA increased from 5 wt% to 10 wt%.

Poly(ethylene octene) grafted with glycidyl methacrylate (POE-g-GMA) was employed to improve the rheological and thermal properties, toughness, and foaming behaviors of poly(lactic acid) (PLA) through a chain extension effect.     

Synthesis and characterization of novel hercynite@sulfuric acid and its catalytic applications in the synthesis of polyhydroquinolines and 2,3-dihydroquinazolin-4(1H)-ones

Herein, we report the synthesis of hercynite@sulfuric acid as a novel nanomagnetic solid acid catalyst, containing the sulfuric acid catalytic sites on the surface of hercynite MNPs as the catalytic support. The as-synthesized nanocomposite was meticulously characterized using a wide range of physicochemical techniques; including, FT-IR, XRD, EDX, X-ray-mapping, SEM and VSM analysis. The catalytic activity of this nanomagnetic material was considered for the synthesis of the diversely substituted polyhydroquinolines and 2,3-dihydroquinazolin-4(1H)-ones under solvent free conditions and also cyclocondensation reactions in ethanol, respectively affording good to excellent yields. Moreover, it is worth mentioning that the heterogeneity of the catalyst was measured through its excellent reusability and hot-filtration test.

Herein, we report the synthesis of hercynite@sulfuric acid as a novel nanomagnetic solid acid catalyst, containing the sulfuric acid catalytic sites on the surface of hercynite MNPs as the catalytic support.     

The preparation,characterization and catalytic activity of Ni NPs supported on porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide)

Herein, we report the synthesis of nickel nanoparticles under mild conditions using porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide) as a protecting/stabilizing agent and sodium borohydride as a reducing agent. The porous cross-linked polymeric support was prepared via combining the use of sol–gel, nanocasting, and crosslinking techniques, in which the p-styrene sulfonamide monomer (PSSA) and N,N′-methylene-bis (acrylamide) (MBA) cross-linker underwent copolymerization on the surface of sodium alginate in the presence of a SiO₂ nanoparticle (NP) template (Alg–PSSA-co-ACA). The prepared catalyst (Alg–PSSA-co-ACA@Ni) showed high catalytic activity for the one-step synthesis of 1,3,4-oxadiazoles from the reaction of hydrazides and aryl iodides through isocyanide insertion/cyclization.

Ni NPs supported on novel porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide) was investigated for the synthesis of 1,3,4-oxadiazoles.     

Design,characterization and catalytic evaluation of halometallic ionic liquid incorporated Nd2O3 nanoparticles ([smim][FeCl4]−@Nd2O3) for the synthesis of N-aryl indeno pyrrole derivatives

Silica modified imidazolium [smim] based halometallic ionic liquids, [smim][MCl₄] (M = Fe, Cu and Zn), were synthesized for the evaluation of acidic and catalytic properties. Among these ILs, [smim][FeCl₄]⁻ was used for the preparation of heterogeneous catalyst ([smim][FeCl₄]⁻@Nd₂O₃) by simple immobilization of IL on Nd₂O₃ nanoparticles. The structure of [smim][FeCl₄]⁻@Nd₂O₃ was established by various techniques including FTIR, Raman, UV-vis DRS, powder XRD, SEM/EDX, elemental mapping, TEM, TGA, EPR and XPS analyses. The stability of nano-catalyst, [smim][ FeCl₄]⁻@Nd₂O₃, was established with the help of zeta potential analysis which showed a value of −40.32 mV lying under the stability range. Potentiometric titration with n-butyl amine was used to evaluate the acidic properties of [smim][MCl₄] as well as [smim][FeCl₄]⁻@Nd₂O₃. The catalytic potential of the material was probed through the one pot synthesis of N-aryl indeno pyrrole derivatives. The results showed excellent performance of the material by producing a high yield (98%) of indeno pyrrole derivatives. A recyclability experiment revealed that the catalyst was efficient in up to five cycles with insignificant loss in catalytic activity. The evaluation of green metrics indicated the sustainability of the present protocol in terms of high atom economy and low E-factor.

Silica modified imidazolium based halometallic ionic liquids, [smim][MCl₄] and [smim][FeCl₄]⁻@Nd₂O₃ were synthesized for the evaluation of acidic and catalytic properties.