Effects of poly(ethylene glycol)-grafted graphene on the electrical properties of poly(lactic acid) nanocomposites

Maleic anhydride was reacted with the armchair edges of graphene nanosheets (GN) via Diels–Alder reaction. Then, polyethylene glycol (PEG) was grafted onto the GN in the presence of anhydride groups through an esterification reaction. The PEG-grafted GN (PEG-g-GN) was characterised via FTIR analysis, thermogravimetric analysis, scanning electron microscopy, Raman spectroscopy and contact angle measurements, proving that PEG was successfully grafted onto the GN surface. The results indicated that PEG-g-GN possessed high electrical conductivity and was dispersed in polylactic acid (PLA). The composites were fabricated by using PEG-g-GN and GN as the conductive agent in the PLA matrix. Owing to the function of PEG molecular chains, PEG-g-GN can be uniformly dispersed in the PLA matrix and improve the tensile strength of composites to 59.46 MPa and conductivity to 9.69 × 10⁻⁴ S cm⁻¹ at a PEG-g-GN content of 1 wt%.

PEG-grafted GN has been synthesized and the effects of modification on the PLA composite conductivity, mechanical properties are investigated.     

Copper sulfide nanostructures: synthesis and biological applications

Over the past few years, considerable attention has been paid to biomedical applications of copper sulfide nanostructures owing to their enhanced physiochemical and pharmacokinetics characteristics in comparison to gold, silver, and carbon nanomaterials. The small-sized Cu_xS_y nanoparticles have the advantage to absorb efficiently in the near-infrared region (NIR) above 700 nm and the absorption can be tuned by altering their stoichiometries. Moreover, their easy removal through the kidneys overpowers the issue of toxicity caused by many inorganic substances. The low cost and selectivity further add to the advantages of Cu_xS_y nanostructures as electrode materials in comparison to relatively expensive materials such as silver and gold nanoparticles. This review is mainly focused on the synthesis and biomedical applications of Cu_xS_y nanostructures. The first part summarizes the various synthetic routes used to produce Cu_xS_y nanostructures with varying morphologies, while the second part targets the recent progress made in the application of small-sized Cu_xS_y nanostructures as biosensors, and their analysis and uses in the cure of cancer. Photoacoustic imaging and other cancer treatment applications are discussed. Research on Cu_xS_y nanostructures will continue to increase over the next few decades, and great opportunities lie ahead for potential biomedical applications of Cu_xS_y nanostructures.

Over the past few years, considerable attention has been paid to biomedical applications of copper sulfide nanostructures owing to their enhanced physiochemical and pharmacokinetics characteristics in comparison to gold, silver, and carbon nanomaterials.     

Large-scale production of CdO/Cd(OH)2 nanocomposites for non-enzyme sensing and supercapacitor applications

Recent advancements in electrode design are substantially linked to state-of-the-art nanomaterial fabrications. Herein, we report a simple one-pot hydrothermal synthesis of Cd(OH)₂ with a platelet-like morphology, which was subsequently annealed at relatively high temperatures to produce a CdO/Cd(OH)₂ nanocomposite for the first time. It was found that the control of thermal treatment allowed tunable charge transport across the nanometre scale due to the presence of CdO and Cd(OH)₂ mixed nanocrystals. The CdO/Cd(OH)₂ nanocrystals offer interesting prospects for the electrocatalytic oxidation of nitrite ions and for supercapacitor applications. The CdO/Cd(OH)₂ nanocomposite was blended with a trace amount of gold NPs for enhancing the electrochemical conductivity and electrocatalytic capability for nitrite oxidation with a sensitivity of 32.9 μA mM⁻¹. It afforded a promising electrocatalyst in a wide concentration range up to 10 mM with a low detection limit of 0.87 μM. Furthermore, the CdO/Cd(OH)₂ nanocomposite electrode was showed to be a highly active and stable supercapacitor, achieving a high specific capacitance in an alkaline medium of about 145 F g⁻¹ at a discharge current of 2.0 A g⁻¹. These results have revealed that the presence of mixed oxide/hydroxide nanocrystals in nanoscale dimensions will be very interesting for various electrochemical applications and provide for a new class of nanodevices based on electrochemistry with unique capabilities.

A simple fabrication of CdO/Cd(OH)₂ nanocomposites was developed and explored for electrochemical-based devices. The nanocomposite is shown to be a sensitive electrode material for nitrite determination in water samples as well as a promising supercapacitor.     

Silylated oligomeric poly(ether-azomethine)s from monomers containing biphenyl moieties: synthesis and characterization

In this study, four new silicon-containing poly(ether-azomethine)s with linear structures were prepared using original silicon and biphenyl moiety-containing monomers: two diamines and two dialdehydes. The oligomeric natures of the samples were established by GPC analysis, which showed chains containing 3 to 5 repetitive units. The monomers and the oligomeric samples were structurally characterized by NMR and FT-IR spectroscopy. The solubilities of the samples in common organic solvents and their thermal behavior enable improvement of their industrial and technological processability. The optical band gaps of the oligomeric samples were estimated from optical measurements (UV-vis), and their electrical behavior in films was determined using the four-point method. The surface arrangements and morphological characteristics of the films were determined via atomic force microscopy measurements. The roughness, area increase percentage and layer stiffness of the films were also measured using this technique.

In this study, four new silicon-containing poly(ether-azomethine)s with linear structures were prepared using original silicon and biphenyl moiety-containing monomers: two diamines and two dialdehydes.     

Phyto-inspired Cu/Bi oxide-based nanocomposites: synthesis,characterization, and energy relevant investigation

A modified and sustainable approach is reported in this research for the synthesis of a spherical-shaped CuO–Bi₂O₃ electrode material for electrochemical studies. Aqueous extract derived from the plant Amaranthus viridis L. (Amaranthaceae) (AVL) was used as a reducing agent for morphological control of the synthesis of CuO–Bi₂O₃ nanocomposites. The modified nanomaterial revealed an average crystal size of 49 ± 2 nm, which matches very well with scanning electron microscopy (SEM) findings. Furthermore, the synthesized material was characterized using Fourier-transform infrared spectroscopy, field emission SEM and energy-dispersive spectroscopy. The optical band gap energy of 3.45 eV was calculated using a Tauc plot. Finally, the bioorganic framework-derived CuO–Bi₂O₃ electrode was tested for energy generating and storage applications and the results revealed a capacitance of 389 F g⁻¹ by cyclic voltammetry, with a maximum energy density of 12 W h kg⁻¹ and power density of 5 kW kg⁻¹. Hydrogen evolution reaction and oxygen evolution reaction studies showed good potential of CuO–Bi₂O₃ as an electrocatalyst for water splitting, with maximum efficiency of the electrode up to 16.5 hours.

Spherical-shaped CuO–Bi₂O₃ electrode material and its electrochemical studies.     

Anisotropic quasi-one-dimensional layered transition-metal trichalcogenides: synthesis,properties and applications

The strong in-plane anisotropy and quasi-1D electronic structures of transition-metal trichalcogenides (MX₃; M = group IV or V transition metal; X = S, Se, or Te) have pronounced influence on moulding the properties of MX₃ materials. In particular, the infinite trigonal MX₆ prismatic chains running parallel to the b-axis are responsible for the manifestation of anisotropy in these materials. Several marvellous properties, such as inherent electronic, optical, electrical, magnetic, superconductivity, and charge density wave (CDW) transport properties, make transition-metal trichalcogenides (TMTCs) stand out from other 2D materials in the fields of nanoscience and materials science. In addition, with the assistance of pressure, temperature, and tensile strain, these materials and their exceptional properties can be tuned to a superior extent. The robust anisotropy and incommensurable properties make the MX₃ family fit for accomplishing quite a lot of compelling applications in the areas of field effect transistors (FETs), solar and fuel cells, lithium-ion batteries, thermoelectricity, etc. In this review article, a precise audit of the distinctive crystal structures, static and dynamic properties, efficacious synthesis schemes, and enthralling applications of quasi-1D MX₃ materials is made.

The strong in-plane anisotropy and quasi-1D electronic structures of transition-metal trichalcogenides (MX₃; M = group IV or V transition metal; X = S, Se, or Te) have pronounced influence on moulding the properties of MX₃ materials.     

Correction: Synthesis and characterization of nanoceria for electrochemical sensing applications

Correction for ‘Synthesis and characterization of nanoceria for electrochemical sensing applications’ by Yeni Wahyuni Hartati et al., RSC Adv., 2021, 11, 16216–16235, DOI: 10.1039/D1RA00637A.

The authors regret that the figures throughout the article were incorrectly referenced. The correct references for each figure are described in

Sustainable xanthophylls-containing poly(ε-caprolactone)s: synthesis,characterization, and use in green lubricants

Three xanthophylls [(3R,3′R,6′R)-lutein (1), (3R,3′S)-zeaxanthin (2), and (3R,3′S)-astaxanthin (3)] were used for the first time as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) catalyzed by tin(ii) 2-ethylhexanoate [Sn(Oct)₂] for the synthesis of novel sustainable xanthophyll-containing poly(ε-caprolactone)s (xanthophylls-PCL). The obtained polyesters were characterized by ¹H and ¹³C NMR, FT-IR, DSC, SEC, and MALDI-TOF MS, and their use as additives in green lubricants was evaluated using a sliding friction test under boundary conditions. Xanthophylls-PCL were obtained with good conversions and with molecular weights determined by SEC to be between 2500 and 10 500 Da. The thermal properties of xanthophyll-polyesters showed a crystalline domain, detected by DSC. Lastly, the green lubricant activity of these polymers was evaluated and the results showed that xanthophylls-PCL could be employed as additives for biodegradable lubricant applications since they have better tribological behavior than current additives, which demonstrates their potential as future commercial materials with interesting eco-friendly properties for diverse applications.

Sustainable polyesters initiators from renewable resources and additives in green lubricants.     

3-(Bromoacetyl)coumarins: unraveling their synthesis,chemistry, and applications

This review emphasizes recent developments in synthetic routes of 3-(bromoacetyl)coumarin derivatives. Also, chemical reactions of 3-(bromoacetyl)coumarins as versatile building blocks in the preparation of critical polyfunctionalized heterocyclic systems and other industrially significant scaffolds are described. Recent advances of 3-(bromoacetyl)coumarins as attractive starting points towards a wide scale of five and six-membered heterocyclic systems such as thiophenes, imidazoles, pyrazoles, thiazoles, triazoles, pyrans, pyridines, thiadiazins as well as fused heterocyclic systems have been reported. Additionally, this review covers a wide range of analytical chemistry, fluorescent sensors, and biological applications of these moieties, covering the literature till May 2021.

This review emphasizes recent developments in synthetic routes of 3-(bromoacetyl)coumarin derivatives.     

Xanthan gum derivatives: review of synthesis,properties and diverse applications

Natural polysaccharides are well known for their biocompatibility, non-toxicity and biodegradability. These properties are also inherent to xanthan gum (XG), a microbial polysaccharide. This biomaterial has been extensively investigated as matrices for tablets, nanoparticles, microparticles, hydrogels, buccal/transdermal patches, tissue engineering scaffolds with different degrees of success. However, the native XG has its own limitations with regards to its susceptibility to microbial contamination, unusable viscosity, poor thermal and mechanical stability, and inadequate water solubility. Chemical modification can circumvent these limitations and tailor the properties of virgin XG to fulfill the unmet needs of drug delivery, tissue engineering, oil drilling and other applications. This review illustrates the process of chemical modification and/crosslinking of XG via etherification, esterification, acetalation, amidation, and oxidation. This review further describes the tailor-made properties of novel XG derivatives and their potential application in diverse fields. The physicomechanical modification and its impact on the properties of XG are also discussed. Overall, the recent developments on XG derivatives are very promising to progress further with polysaccharide research.

Due to presence of hydroxy and carboxy functional groups, xanthan gum is amenable to various chemical modification for producing derivatives such as carboxymethyl xanthan and carboxymethyl hydroxypropyl xanthan with desirable properties for end use.     

Phosphorescent iridium-containing nanomicelles: synthesis,characterization and preliminary applications in nanomedical imaging

Diagnostic nanomedicine constantly requires the development of novel contrast agents with intrinsic imaging capabilities. Phosphorescent Ir(iii)-complexes represent good candidates when delivered through polymeric nanoparticles. In this work, we propose a biocompatible nanoparticle made from an intrinsically phosphorescent copolymer, synthesized directly with an imaging tag present on its backbone. Polymeric nanoparticles can be obtained with the exact amount of phosphorescent moieties needed to maximize their output signal. Complete characterization and ex vivo studies confirmed that this nanosystem is suitable as a future diagnostic tool.

We propose a biocompatible nanoparticle made from an intrinsically phosphorescent copolymer, synthesized directly with an imaging tag present on its backbone.     

First cycloruthenation of 2-alkenylpyridines: synthesis,characterization and properties

Several cyclometalated ruthenium complexes 1–5 with 2-alkenylpyridines as C,N-chelating ligands were synthesized and then characterized by NMR, MS, IR and UV-Vis spectra. According to the single crystal of complex 2, it is evident that carbon from vinyl group is successfully bonded to Ru(ii) center. Moreover, the Ru–N bond trans to the Ru–C bond is elongated (2.127(5) Å), which is consistent with the strong trans effect of the carbon atom compared to that of the nitrogen atom. With different electron-donating groups linked to vinyl, these complexes exhibited regular changes in MLCT absorption bands, which were identified by UV-Vis and CV spectra in combination with DFT and TD-DFT. Interestingly, protonated intermediate species of these complexes in acidic solutions were tracked by the absorption changes and MS spectra, which displayed a possible protonation process of these complexes with the cleavage of Ru–C σ bonds.

Five cycloruthenated 2-(alkenyl)pyridine derivatives and their protonated species without the release of cyclometalating ligands were first captured.     

Liquid crystal behavior,photoluminescence and gas sensing: A new series of ionic liquid crystal imidazole and benzoimidazole bearing chalcone groups,synthesis and characterization

Four new series of chalcones containing imidazole bromonium and benzimidazole bromonium salts with spacer alkyl chains (C_n, n = 2 and 4) were synthesized and the chemical structure, thermal behavior, photoluminescence and gas sensing were characterized by several technical methods. The studies have indicated similar mesomorphic properties of the synthesized compounds, dependent on the terminal alkyl-chain and lengths of the alkoxy-spacer. Almost compounds with shorter alky chains, 4a–4e, 5a–5c, 6a–6c and 7a–7d, did not show liquid crystal properties, while the results of other compounds confirm the existence of smectic A in cooling and heating cycles. Photoluminescence of compounds 5a–5i and 7a–7i was also studied. The emission in the blue region reveals that the material has blue light emission properties. Sensing behavior of compounds 4i and 5i was investigated for NH₃ and NO₂ gases. The sensors exhibited high sensitivity toward NH₃, while sensitivity toward the oxidizing gas NO₂ is lower.

Four new series of chalcones containing imidazole bromonium and benzimidazole bromonium salts with spacer alkyl chains (C_n, n = 2 and 4) were synthesized and their chemical structure, thermal behavior, photoluminescence and gas sensing ability were characterized.     

The synthesis,characterization and applications of poly[N-isopropylacrylamide-co-3-allyloxy-1,2-propanediol] grafted onto modified magnetic nanoparticles

In this paper, a novel method is investigated for the extraction, determination, and delivery of ceftazidime in simulated gastric and real biological fluids such as serum plasma and urine in in vitro drug delivery systems. A new polymer as a nano-sorbent was synthesized by the surface grafting of [N-isopropylacrylamide-co-3-allyloxy-1,2-propanediol] onto modified magnetic nano-particles by 3-mercaptopropyltrimethoxysilane and it was characterized by FT-IR, CHN, SEM, TEM, VSM, TGA, and zeta potential analyses. The effects of main parameters such as pH, reaction time, temperature, and solvents were evaluated for ceftazidime removal. The results indicate that the newly synthesized polymer can be successfully applied for biomedical applications and drug delivery.

In this paper, a novel method is investigated for the extraction, determination, and delivery of ceftazidime in simulated gastric and real biological fluids such as serum plasma and urine in in vitro drug delivery systems.     

Rare earth complexes using azobenzene-containing poly(aryl ether)s with different absorption wavelengths as macromolecular ligands: synthesis,characterization, fluorescence properties and fabrication of fluorescent holographic micropatterns

In this paper, two novel azobenzene-containing poly(aryl ether)s with different absorption wavelengths were synthesized via Ullmann coupling and Sonogashira coupling, respectively. The obtained polymers were characterized and evaluated by elemental analysis, IR, ¹H NMR, UV-vis, DSC and TGA. Rare earth complexes were prepared by using the two novel azobenzene-containing poly(aryl ether)s as macromolecular ligands. The obtained rare earth complexes were characterized by elemental analysis, IR and WAXD. The influence of the absorption wavelength of azobenzene chromophores on the fluorescent properties was investigated. The polymer whose absorption wavelength was far from the excitation wavelengths of the rare earth complexes showed a much larger fluorescence intensity. By exposing the films of the rare earth complexes to two interference laser beams, SRGs can be formed on the films and can also be detected by fluorescence microscopy measurement.

Preparation and fluorescence properties of rare earth complexes using azobenzene-containing poly(aryl ether)s with different absorption wavelengths as macromolecular ligands.     

Enhanced mechanical,thermal, and UV-shielding properties of poly(vinyl alcohol)/metal–organic framework nanocomposites

Metal–organic framework (HKUST-1) nanoparticles were successfully synthesized, and poly(vinyl alcohol) (PVA)/HKUST-1 nanocomposite films were fabricated by a simple solution casting method. Our results showed that the addition of HKUST-1 caused a remarkable enhancement in both thermal stability and mechanical properties of the PVA nanocomposites, due to the homogeneous distribution of HKUST-1 and the strong interfacial interactions between PVA and HKUST-1. With incorporation of 2 wt% HKUST-1, the degradation temperature of the nanocomposites was about 33 °C higher than that of pure PVA. At the same time, the Young''s modulus and tensile strength of the nanocomposites was approximately 137% and 32% higher than those of pure PVA, respectively. Moreover, the PVA/HKUST-1 nanocomposites also showed strikingly enhanced UV-shielding ability as well as satisfactory visible light transmittance, which revealed that HKUST-1 nanoparticles could act as a good UV absorber in nanocomposites. This work provides a novel and simple method for producing UV-shielding materials with simultaneously enhanced thermal and mechanical properties, which have potential applications in UV protection areas.

PVA/HKUST-1 nanocomposites prepared by a simple solution casting method displayed significantly enhanced thermal stability, mechanical and UV-shielding properties.     

Triazole-based cross-linkers in radical polymerization processes: tuning mechanical properties of poly(acrylamide) and poly(N,N-dimethylacrylamide) hydrogels

Triazole-based cross-linkers with different spacer lengths and different functional end groups (acrylamides, methacrylamides, maleimides and vinylsulfonamides) were synthesized, investigated for cytotoxic and antibacterial activity, and incorporated into poly(acrylamide) (PAAm) and poly(N,N-dimethylacrylamide) (PDMAAm) hydrogels by free-radical polymerization. Hydrogels prepared with different cross-linkers and cross-linker contents between 0.2% and 1.0% were compared by gel yields, equilibrium degrees of swelling (S) and storage moduli (G′). Generally with increasing cross-linker content, G′ values of the hydrogels increased, while S values decreased. The different polymerizable cross-linker end groups resulted in a decrease of G′ in the following order for cross-linkers with C₄ spacers: acrylamide > maleimide > methacrylamide > vinylsulfonamide. Longer cross-linker alkyl spacer lengths caused an increase in G′ and a decrease in S. Independent of the cross-linker used, a universal correlation between G′ and equilibrium polymer volume fraction ϕ was found. For PAAm hydrogels, G′ ranged between 4 kPa and 23 kPa and ϕ between 0.07 and 0.14. For PDMAAm hydrogels, G′ ranged between 0.1 kPa and 4.9 kPa and ϕ between 0.02 and 0.06. The collected data were used to establish an empirical model to predict G′ depending on ϕ. G′ of PAAm and PDMAAm hydrogels is given by G′ = 4034 kPa ϕ^2.66 and G′ = 4297 kPa ϕ^2.46, respectively.

Poly(acrylamide) and poly(N,N-dimethylacrylamide) hydrogels were prepared by free-radical polymerization using triazole-based cross-linkers with different spacer lengths and functional end groups and hydrogel properties were assessed.     

A new cobalt(ii) meso-porphyrin: synthesis,characterization, electric properties and application in the catalytic degradation of dyes

In this work, a new porphyrin, 5,10,15,20-tetrakis{4-[((4-methoxyphenyl)acetyl)oxy]phenyl}porphyrin (H₂TMAPP) (1), and its cobalt complex [Co^II(TMAPP)] (2) were synthesized in good and quantitative yields, respectively. The chemical structures of these synthesized compounds were confirmed by FT-IR, ¹H NMR, MS, UV-visible, and fluorescence spectroscopy. Their photophysical properties, namely their molar extinction coefficients (∑), fluorescence quantum yields (Φ_f) and lifetimes (τ_f), were determined and compared with those of meso-tetraphenylporphyrin. Furthermore, their electrochemical behaviours were examined using cyclic voltammetry (CV). Dielectric properties such as the conductivity (σ) and the real (M′) and imaginary (M′′) parts of the dielectric modulus were investigated as a function of temperature and frequency. The impedance analysis was carried out using Cole–Cole plots to elucidate the electrical conduction mechanism. The catalytic power and the adsorption properties of the prepared compounds were studied for methylene blue (MB) and crystal violet (CV) degradation. The results reveal that the studied compound [Co^II(TMAPP)] can be used as a catalyst for the decolourisation of dyes in the presence of H₂O₂.

In this work, a new porphyrin, 5,10,15,20-tetrakis{4-[((4-methoxyphenyl)acetyl)oxy]phenyl}porphyrin (H₂TMAPP) (1), and its cobalt complex [Co^II(TMAPP)] (2) were synthesized in good and quantitative yields, respectively.     

Tetranuclear Cu(ii)-chiral complexes: synthesis,characterization and biological activity

Tetranuclear chiral Cu(ii)-Schiff-base complexes S-1 and R-1, were synthesised using enantiomerically pure (S)-(H₂vanPheol) and (R)-(H₂vanPheol) ligands respectively in the ratio of 1 : 1 of Cu(NO₃)₂ to (S/R)-(H₂vanPheol) in MeOH at room temperature. A pair of polynuclear chiral Cu(ii)-cluster complexes were characterized using single-crystal X-ray diffraction, elemental analysis, infrared and CD spectroscopy. The results revealed the importance of these chiral ligands encouraging the arrangement of copper metal in non-centrosymmetric polar packing. The potential of the novel [Cu₄(S/R-vanPheol)₂(S/R-HvanPheol)₂(CH₃OH)₂](NO₃)₂ complexes as biologically active compounds was assessed in particular regarding their anti-proliferative and anti-microbial properties.

A pair of tetranuclear chiral Cu(ii)-Schiff-base complexes were synthesized using enantiomerically pure (S)-H₂L and (R)-H₂L ligands. These were characterised using single-crystal X-ray diffraction and CD spectroscopy and their biological activity tested.