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.     

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.     

Comb-shaped cardo poly(arylene ether nitrile sulfone) anion exchange membranes: significant impact of nitrile group content on morphology and properties

A series of comb-shaped cardo poly(arylene ether nitrile sulfone) (CCPENS-x) materials were synthesized by varying the content of nitrile groups as anion exchange membranes (AEMs). The well-designed architecture of cardo-based main chains and comb-shaped C10 long alkyl side chains bearing imidazolium groups was responsible for the clear microphase-separated morphologies, as confirmed by atomic force microscopy. The ion exchange capacity (IEC) of the AEMs ranged from 1.56 to 1.65 meq. g⁻¹. With strong dipole interchain interactions, the effects of nitrile groups on the membrane morphology and properties were investigated. With the nitrile group content increasing from CCPENS-0.2 to CCPENS-0.8, CCPENS-x revealed larger and more interconnected ionic domains to form more efficient ion-transport channels, thus increasing the corresponding ionic conductivity from 25.8 to 39.5 mS cm⁻¹ at 30 °C and 58.6 to 83 mS cm⁻¹ at 80 °C. Furthermore, CCPENS-x with a higher content of nitrile groups also exhibited lower water uptake (WU) and swelling ratio (SR), and better mechanical properties and thermal stability. This work presents a promising strategy for enhancing the performance of AEMs.

A series of comb-shaped cardo poly(arylene ether nitrile sulfone) (CCPENS-x) materials were synthesized by varying the content of nitrile groups as anion exchange membranes (AEMs).     

Copper alumina @ poly (aniline-co-indole) nanocomposites: synthesis,characterization, electrical properties and gas sensing applications

Poly(aniline-co-indole)/copper alumina (PANI-co-PIN/Cu–Al₂O₃) with excellent AC conductivity, dielectric properties, and ammonia gas detecting capabilities were synthesised via in situ chemical oxidative polymerization. The presence of Cu–O bonding vibrations and shift of some characteristic peaks in the Fourier transform infrared spectroscopy (FT-IR) revealed the successful encapsulation of Cu–Al₂O₃ nanoparticles in the copolymer. The XRD studies showed the crystalline peaks of Cu–Al₂O₃ in the PANI-co-PIN nanocomposites. The high-resolution transmission electron microscopy (HR-TEM) images confirmed the reinforcement of the inorganic moiety in the copolymer. The results from thermogravimetric analysis (TGA) showed that the inclusion of Cu–Al₂O₃ in the copolymer matrix greatly increases the thermal stability of PANI-co-PIN. The alternate current (AC) conductivity and dielectric properties of nanocomposites were higher than pure PANI-co-PIN. The improved electrical properties of nanocomposites were due to strong contact between the copolymer and metal oxide surfaces. The gas sensing properties of synthesized copolymer nanocomposites showed excellent sensitivity and response towards ammonia gas at room temperature. The PANI-co-PIN/5 wt% Cu–Al₂O₃ nanocomposite has the best gas sensing characteristics. The higher AC conductivity, dielectric properties and gas sensing characteristics of PANI-co-PIN/Cu–Al₂O₃ might be used to develop electrochemical sensing devices.

PANI-co-PIN/Cu–Al₂O₃ nanocomposites synthesised via in situ polymerization showed excellent electrical and NH₃ gas sensing properties.     

A novel profluorescent paramagnetic diaza-crown ether: synthesis,characterization and alkaline metal-ion complexation

Starting from Kryptofix 22 two different branches were covalently attached through the nitrogen atoms, one containing a fluorescent moiety and the other the stable free radical TEMPO. The novel derivative exhibits fluorescence and paramagnetic properties, while the diaza-crown part ensures the affinity for alkaline metal-ions.

Starting from Kryptofix 22 two different branches were covalently attached through the nitrogen atoms, one containing a fluorescent moiety and the other the stable free radical TEMPO.

Fluorescence¹ and electron paramagnetic resonance (EPR)² are two versatile techniques that found useful applications in various fields, especially for detection purposes, taking advantage of the two very different working principles, i.e. fluorescence as an optical method, and EPR as a magnetic method. Combination of these two techniques is possible by coupling in the same molecule two different moieties, one fluorescent and one paramagnetic, yielding a dual behaviour of the resulted compound, usually called profluorescent free radicals.³ Such examples are very useful for the detection of numerous biological analytes with very interesting performance.⁴ Stable free radicals of nitroxide type are often encountered in the literature due to their great stability in an open atmosphere (they do not react with oxygen, nor dimerize) over a large range of temperatures. Usually, covalent attachment of a nitroxide moiety to a fluorescent compound leads to intramolecular fluorescence quenching. By switching off the paramagnetic centre (i.e. via reduction reactions), the fluorescence can be restored, providing dual paramagnetic-fluorogenic probes useful as detection tools.Our previous work⁵ in the field of profluorescent nitroxides involved synthesis of novel compounds based on a new type of fluorogenic core, 2,5-disubstituted-1,3,4-oxadiazoles and TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) stable free radical, as paramagnetic component that were demonstrated useful in the detection and quantification of some analytes, i.e. sodium ascorbate.Continuing this topic, we aimed for preparation of new profluorescent nitroxides that contain a third functional unit. Aza-crown ether moieties⁶ are widely encountered in supramolecular assemblies, for synthesis of host-guest systems, generally acting as receptors for metal-ions.⁷ Combining all these structural motifs may result in unusual chemical, optical, or electronic properties, considering that aza-crown ethers covalently functionalized with fluorophores were successfully used in analytical chemistry as (chemo)sensors, due to high sensitivity of the fluorescence technique and the affinity of the aza-crown ether moiety for specific cations.⁸ Whereas fluorescent (aza)crown ethers are widely encountered in literature, spin-labelled (aza)crown ethers were much less explored; very few available papers describe, besides the expected complexation, structural and dynamical information about the environmental recognition processes.⁹To the best of our knowledge, there is only one paper¹⁰ describing a double crown ether sensor, containing a fluorophore (acridine) and a paramagnetic core (nitroxide), covalently linked through a 18-crown-6 ether moiety. In this context, we describe the synthesis and characterisation of a new nitrobenzo-1,2,5-oxadiazole (NBD) and/or TEMPO functionalised compounds in which the fluorophore and free radical are linked through a diaza-crown ether (Scheme 1). We investigated the possibility to switch between luminescence and paramagnetism as well as the ability to form complexes with alkaline metal-ions. The choice for NBD as fluorogenic unit was based on its widely use for development of chemosensors for various analytes i.e. cysteine, homocysteine, glutathione, vitamin C.¹¹ NBD-chloride is a versatile reagent that is highly reactive in S_NAr with common N, O or S nucleophiles, and, therefore, it was one of the first reagents used in non-specific protein labelling.¹²Open in a separate windowScheme 1Synthesis of compounds 3 and 4: (a) DCM, Et₃N, rt, overnight, 62%; (b) 4-carboxy-TEMPO, PyBOP, DIPEA, DCM, rt, 4h, 81%.Synthesis of the novel fluorescent diaza-crown ether 3 was accomplished by reaction of the furazane 1 and the aza-crown ether 2, well known as Kryptofix 22, in a good yield (62%) by simply stirring the two reactants in dichloromethane (DCM), using triethylamine as base. Compound 3 has not been described up to now. However, the disubstituted aza-crown derivative was previously obtained through a slightly modified procedure.^8b,13 Further, compound 3 underwent an amide coupling reaction with 4-carboxy-TEMPO, using common amide coupling conditions: activating reagent PyBOP (benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluoro-phosphate) and DIPEA (N,N-diisopropylethylamine) as base in DCM. The reaction proceeded smoothly, in a very short reaction time, in 81% isolated yield.The NMR study (Fig. 1) of compound 3 was performed in DMSO-d₆ and CDCl₃ (see ESI^† for full spectra). In the aromatic region of the spectrum registered in DMSO-d₆, we could observe a downfield of the chemical shifts corresponding to the signals of the aromatic protons (δ_H5 = 8.46/8.40 ppm and δ_H6 = 6.54/6.21 ppm for DMSO-d₆/CDCl₃), whereas in the aliphatic region, the signals corresponding to the methylene protons of the ether residue are slightly shielded (i.e. δ_H8/8'' = 4.23/4.30 ppm δ_H9/9'' = 3.79/3.86 ppm for DMSO-d₆/CDCl₃). The data obtained in DMSO-d₆ is consistent with previously reported data for the disubstituted derivative.^8b,13 However, the high shield of the signals corresponding to the aromatic protons, especially H₆ was intriguing. Structurally similar aza-crown ethers bearing only one nitrogen atom displayed a chemical shift corresponding to H₆ at δ = 6.35 ppm.^8b Previous studies showed that the conformation of the aza-crown ethers is highly dependent on the substituents of the nitrogen atoms, which undergo inversion when substituted, with the lone pair electrons oriented toward the interior of the cavity.¹⁴ In this context, the high shield of the aromatic protons in the vicinity of the aza-crown ether moiety could be caused by conformation changes in environments of different polarities.Open in a separate windowFig. 1 ¹H NMR spectra (fragments, 500 MHz) of compound 3 in CDCl₃ (top) and DMSO-d₆ (bottom).Another interesting observation with respect to previous reported data is the value of the chemical shifts corresponding to protons H_8/8'' and H_9/9'' which are significantly downfield compared to similar compound bearing N-methyl groups (δ = 2.74 ppm and δ = 3.56 ppm).¹⁴ A possible hindered rotation between the aza-crown ether and the p-nitrofurazane moieties may also be the cause of the signals broadening. This could be observed for the signal corresponding to H₈ (δ = 4.23 ppm, broad signal). The carbon spectrum also displays broad signals of the carbons labelled with C-8 and C-9 (δ = 53.6 ppm and δ = 68.6 ppm, respectively, see ESI^†). Finally, the proton of the free nitrogen atom is visible in the spectrum registered in CDCl₃, at δ = 2.67 ppm, in accordance to previously reported data for similar compounds, although slightly downfield shifted.¹⁵The absorption spectrum of compound 3 registered in DMSO at 20 μM (Fig. 2) showed absorption maxima around 350 and 500 nm (13 indicating that attachment of the diaza-crown ether moiety did not influence the absorption behaviour of the oxadiazole. Variation of absorption maxima according to the solvent used, as inferred from the literature data^8b confirm our results and the slight solvatochromic behaviour of the NBD-derived compound.Open in a separate windowFig. 2Top: Left – absorption spectra of compounds 3 and 4, recorded in DMSO at 2 × 10⁻⁵ M. Right: Excitation (dotted lines) and emission (plain lines) of compounds 3 and 4, recorded in DMSO and 1% DMSO in PBS buffer at 10⁻⁴ M. Bottom: Left – solid state emission spectra of compounds 3 and 4 (λ_ex = 490 nm). Right – emission spectra (λ_exc = 500 nm) of compound 4 with aqueous solutions (MiliQ water) of LiClO₄, NaClO₄, KClO₄ and CsClO₃ (individual and equimolar amounts) at final concentration of the organic compounds of 10⁻⁴ M.Absorption and emission wavelength for compounds 3 and 4 in solution and solid state

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.     

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.     

A new COF linked by an ether linkage (–O–): synthesis,characterization and application in supercapacitance

A new COF (NWNU-COF-4) linked by an aryl ether bond (Ar–O–Ar) was synthesized by the condensation reaction of 2,4,6-trihydroxypyrimidine and trinitrophenol under simple and easy reaction conditions. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N₂ adsorption–desorption, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to characterize the product. The BET specific surface area of NWNU-COF-4 was 21.33 m² g⁻¹, and its pore size was about 1.351 nm. Additionally, this method of preparation was simple and cheap. The electrochemical measurements showed that the synthesized NWNU-COF-4 had excellent pseudocapacitive performance with maximum specific capacitance of 133.44 F g⁻¹ at 0.3 A g⁻¹ in 6 mol L⁻¹ KOH electrolyte. When the current density increased by 10 times (3.0 A g⁻¹), the specific capacitance was 114.12 F g⁻¹, and the retention rate was 82%. After 10 000 GCD cycles, the capacitance still kept 94% of its initial capacitance.

A new COF (NWNU-COF-4) linked by aryl ether bonds was readily synthesized by condensation of 2,4,6-trihydroxypyrimidine and trinitrophenol. It exhibited excellent pseudocapacitive performance and cycling stability, with promising application as a supercapacitor electrode.     

Two novel aromatic hydrocarbons: facile synthesis,photophysical properties and applications in deep-blue electroluminescence

Two efficient novel fluorescent naphthalene and fluorene-based aromatic hydrocarbon isomers (1 and 2) are prepared and investigated for organic electroluminescence. These compounds show bright violet to deep-blue emission, narrow full width at half maximum (52 nm), and high photoluminescence efficiency (e.g. 0.61 in CH₂Cl₂, 0.67 in film). Alternation of substituent position on the naphthalene moiety can give rise to remarkable emission variation. The relatively large torsion angle between naphthalene and fluorene suppresses the π–π interactions by weakening the intermolecular interactions in the solid state, which can result in highly efficient fluorescence. Moreover, the 1931 Commission Internationale de L''Eclairage coordinates and maximum emission peak for deep-blue electroluminescence based on 1 are (0.16, 0.08) and 410 nm, respectively.

Novel solution processable aromatic hydrocarbons have been designed and synthesized for deep-blue OLEDs with a maximum emission peak of 410 nm and CIE coordinates of (0.16, 0.08).     

Poly(ethylene glycol)-human serum albumin-paclitaxel conjugates: preparation, characterization and pharmacokinetics.

Paclitaxel has been found to be very effective against several human cancers, such as ovarian, breast and non-small cell lung cancer and has received marketing approval for metastatic cancers. One of main problems with its use is its poor solubility, which makes irritant solubilitazion agents necessary. In previous research we demonstrated that linkage to human serum albumin (HSA) was useful to increase the in vivo performance of paclitaxel. In this article, in order to improve stability and solubility of paclitaxel conjugate, we linked covalently a monomethoxy poly(ethylene glycol) (mPEG) chain to HSA. New thioimidate mPEG derivatives, highly reactive and stable, were used and two different conjugates (with PEG of molecular mass 2 or 5 kDa) were prepared, purified and characterized. The antitumor activity of the free drug and conjugates was tested on three different tumor cell lines. The PEG grafted conjugates maintained high cytotoxicity, similar to that of ungrafted conjugates, with efficient cell binding and internalization followed by release of the drug inside the cell. The changes in pharmacokinetics and distribution of radio-labelled conjugates were evaluated by i.v. administration to mice and compared with those of the free drug and ungrafted conjugates. The total clearance was reduced (from 3.6 ml/h for free drug to 2.9, 1.97 and 1.41 for ungrafted, 2 and 5 kDa PEG conjugates, respectively). Organ uptake was reduced, in particular by liver and spleen.     

Structure and properties of halogen-free flame retardant and phosphorus-containing aromatic poly(1,3,4-oxadiazole)s fiber

In order to improve the flame retardance of aromatic polyoxadiazole (p-POD) fiber, a series of phosphorus-containing PODs (pho-POD) were synthesized by introducing triaryl phosphine oxide (TPO) units into the main chains of p-POD using hydrazine sulfate, terephthalic acid and bis(p-carboxy)phenyl phosphine oxide (BCPPO) as monomers, and then halogen-free flame resistant pho-POD fibers were obtained from wet spinning. The structure and properties of the pho-POD fibers were characterized and measured in detail using the methods of wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), oxygen bomb calorimeter, Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) etc. The results show that the introduction of TPO units resulted in the weakening of the crystallization ability, the formation of the poriferous and lax interior structure, the slight decrease in the thermal stability and mechanical properties of the POD fibers. However, the value of LOI obviously increased from 28% to 35%, and the gross heat of combustion (GHC) decreased from 19.72 MJ kg⁻¹ to 17.84 MJ kg⁻¹ with the increase in the content of the BCPPO. Moreover, the combustion residue of pho-POD fiber revealed a smooth, dense and non-porous carbon layer, which could effectively play a role of oxygen barrier and enhance the flame resistance. From the above results, it can be concluded that the flame resistance of the POD fiber could be improved significantly after introducing the TPO unit. The results of Py-GC/MS illustrate that the TPO unit of pho-POD could inhibit the production of volatile products, which could be confirmed that the mechanism of enhancing the flame retardancy by introducing TPO units was mainly the flame retardation of the condensed phase.

The flame resistance of POD fibers can be improved significantly by introducing TPO units into the main chains.     

MIL-101(Cr)–cobalt ferrite magnetic nanocomposite: synthesis,characterization and applications for the sonocatalytic degradation of organic dye pollutants

In this study, for the first time, a novel magnetically recyclable MIL-101(Cr)/CoFe₂O₄ nanocomposite was prepared via a facile solvothermal method. The morphology, structural, magnetic and optical properties of the nanocomposite were characterized via field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), UV-visible spectroscopy (UV-visible) and BET surface area analysis. Furthermore, the sonocatalytic activity of the MIL-101(Cr)-based magnetic nanocomposite was explored for the degradation of organic dye pollutants such as Rhodamine B (RhB) and methyl orange (MO) under ultrasound irradiation in the presence of H₂O₂. Under optimized conditions, the degradation efficiency reached 96% for RhB and 88% for MO. The sonocatalytic activity of MIL-101(Cr)/CoFe₂O₄ was almost 12 and 4 times higher than that of the raw MIL-101(Cr) and pure CoFe₂O₄, respectively. The improved sonocatalytic performance of the as-prepared binary nanocomposite can be attributed to the relatively high specific surface area of MIL-101(Cr) and magnetic property of CoFe₂O₄, as well as the fast generation and separation of charge carriers (electrons and holes) in MIL-101(Cr) and CoFe₂O₄. In addition, the trapping tests demonstrated that ·OH radicals are the main active species in the dye degradation process. Moreover, the most influencing factors on the sonocatalytic activity such as the H₂O₂ amount, initial dye concentration and catalyst dosage were investigated. Finally, the nanocomposite was magnetically separated and reused without any observable change in its structure and performance even after four consecutive runs.

A magnetically separable MIL-101(Cr)/CoFe₂O₄ binary nanocomposite was prepared via a hydrothermal route and applied as a sonocatalyst for the efficient degradation of organic dyes.     

New triorganotin(iv) compounds with aromatic carboxylate ligands: synthesis and evaluation of the pro-apoptotic mechanism

Three new organotin(iv) carboxylate compounds were synthesized and structurally characterized by elemental analysis and FT-IR and multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy. Single X-ray crystallography reveals that compound C2 has a monoclinic crystal system with space group P2₁/c having distorted bipyramidal geometry defined by C₃SnO₂. The synthesized compounds were screened for drug-DNA interactions via UV-Vis spectroscopy and cyclic voltammetry showing good activity with high binding constants. Theoretical investigations also support the reactivity of the compounds as depicted from natural bond orbital (NBO) analysis using Gaussian 09. Synthesized compounds were initially evaluated on two cancer (HeLa and MCF-7) cell lines and cytotoxicity to normal cells was evaluated using a non-cancerous (BHK-21) cell line. All the compounds were found to be active, with IC₅₀ values less than that of the standard drug i.e. cisplatin. The cytotoxic effect of the most potent compound C2 was confirmed by LDH cytotoxicity assay and fluorescence imaging after PI staining. Apoptotic features in compound C2 treated cancer cells were visualized after DAPI staining while regulation of apoptosis was observed by reactive oxygen species generation, binding of C2 with DNA, a change in mitochondrial membrane potential and expression of activated caspase-9 and caspase-3 in cancer cells. Results are indicative of activation of the intrinsic pathway of apoptosis in C2 treated cancer cells.

Three new organotin(iv) carboxylate compounds were synthesized and structurally characterized by elemental analysis and FT-IR and multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy.     

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.     

Deficient cholesterol side chain oxidation in patients without peroxisomes (Zellweger syndrome): evidence for the involvement of peroxisomes in bile acid synthesis in man

The absence of peroxisomes in patients with the cerebro-hepato-renal (Zellweger) syndrome is accompanied by a number of biochemical abnormalities including the accumulation of the bile acid intermediates di- and trihydroxycoprostanoic acid. In this paper we show that there is a marked deficiency in the oxidative side chain cleavage of cholesterol in liver from Zellweger patients. These findings not only provide an explanation for the low levels of the major naturally occurring bile acids, cholic acid and chenodeoxycholic acid and the accumulation of di- and trihydroxycoprostanoic acid in Zellweger patients, but also suggest that peroxisomes are essential in bile acid synthesis in man.     

Green synthesis of copper nanoparticles from an extract of Jatropha curcas leaves: characterization,optical properties,CT-DNA binding and photocatalytic activity

The green synthesis of copper nanoparticles (CuNPs) using a leaf extract from Jatropha curcas (JC) has been documented in our present research work. The existence of flavonoids, tannins, glycosides, and alkaloids was confirmed by the phytochemical analysis of the plant extract and these chemicals can be used as reducing, stabilizing and capping agents. After six months, the JC-CuNPs were found to be stable without any evidence of agglomeration. The JC-CuNPs were characterised by XRD, FT-IR, SEM, TEM and UV-vis spectrophotometry. The average particle and crystal sizes of the JC-CuNPs were found to be 10 ± 1 and 12 ± 1 nm, respectively. The SPR peaks were found at 266 and 337 nm, measured using electronic spectroscopy, and the calculated optical band gap was found to be 3.6 eV at 337 nm, indicating the semiconductor behaviour of the JC-CuNPs. JC-CuNPs have potential photocatalytic activity against methylene blue (MB) compared with other dyes in the presence of sunlight and the rate constant (k) value is 2.30 × 10⁻⁴ s⁻¹. The JC-CuNPs also have a binding property with CT-DNA through an intercalation mode and the binding constant (K_b) is 1.024 × 10² M⁻¹.

The green synthesis of copper nanoparticles (CuNPs) using a leaf extract from Jatropha curcas (JC) has been documented in our present research work.     

Heterometallic cobalt(ii) calix[6 and 8]arenes: synthesis,structure and electrochemical activity

Heterometallic cobalt p-tert-butylcalix[6 and 8]arenes have been generated from the in situ reaction of lithium reagents (n-BuLi or t-BuOLi) or NaH with the parent calix[n]arene and subsequent reaction with CoBr₂. The reverse route, involving the addition of in situ generated Li[Co(Ot-Bu)₃] to p-tert-butylcalix[6 and 8]arene, has also been investigated. X-ray crystallography reveals the formation of complicated products incorporating differing numbers of cobalt and lithium or sodium centers, often with positional disorder, as well as, in some cases, the retention of halide. The electrochemical analysis revealed several oxidation events related to the subsequent oxidation of Co(ii) centers and the reduction of the metal cation at negative potentials. Moreover, the electrochemical activity of the phenol moieties of the parent calix[n]arenes resulted in dimerized products or quinone derivatives, leading to insoluble oligomeric products that deposit and passivate the electrode. Preliminary screening for electrochemical proton reduction revealed good activity for a number of these systems. Results suggest that [Co₆Na(NCMe)₆(μ-O)(p-tert-butylcalix[6]areneH)₂Br]·7MeCN (6·7MeCN) is a promising molecular catalyst for electrochemical proton reduction, with a mass transport coefficient, catalytic charge transfer resistance and current magnitude at the catalytic turnover region that are comparable to those of the reference electrocatalyst (Co(ii)Cl₂).

Reactions between p-tert-butylcalix[6 and 8]arenes and lithium or sodium reagents led to complex structures often with positional disorder. Such systems are capable of electrochemical proton reduction.     

Poly(N,N-dimethylacrylamide-octadecyl acrylate)-clay hydrogels with high mechanical properties and shape memory ability

As a type of important intelligent materials, shape memory hydrogels (SMHs) have gathered a lot of interest due to their promising applications. However, preparing SMHs with excellent mechanical properties still remains a big challenge. In this study, a new type of SMHs with excellent mechanical strength is created. The SMHs were prepared by free radical micellar polymerization of hydrophobic monomer (octadecyl acrylate) with gelatin as emulsifier in a aqueous system containing hydrophilic monomer (N,N-dimethylacrylamide, DMA) and clay as reinforcing filler. The polymerization provided physically cross-linked network structures constructed by two non-covalent interactions, i.e. hydrophobic association formed by monomer units and multiple H-bonds among inorganic clay, gelatin and DMA. A judicious combination of the two physically cross-linked networks significantly improved the mechanical strength of hydrogels. More interestingly, the hydrogels demonstrated shape memory behavior due to the hydrophobic poly(octadecyl acrylate) domains. The novel SMHs are expected to find practical applications as biomaterials.

As a type of important intelligent materials, shape memory hydrogels (SMHs) have gathered a lot of interest due to their promising applications.     

A series of Mn(i) photo-activated carbon monoxide-releasing molecules with benzimidazole coligands: synthesis,structural characterization,CO releasing properties and biological activity evaluation

Five Mn(i) photo-activated carbon monoxide-releasing molecules (photo-CORMs) with benzimidazole coligands, namely [MnBr(CO)₃L1] (1, L1 = 2-(2-pyridyl)benzimidazole), [Mn(CO)₂L1(PPh₃)₂](ClO₄) (2), [MnBr(CO)₃L2] (3, L2 = 2,2′-bisbenzimidazole), [MnBr(CO)₃L3]·CH₃OH (4, L3 = 2,6-bis(benzimidazole-2′-yl)pyridine) and fac-[MnBr(CO)₃L4] (5, L4 = 2,4-bis(benzimidazole-2′-yl) pyridine) were synthesized by reactions of MnBr(CO)₅ with complexes L1–L4, respectively, and characterized via single crystal X-ray diffraction, elemental analysis, ¹H-NMR, ¹³C-NMR, IR, UV-vis and fluorescence spectroscopy. The CO-release properties of 1–5 were investigated using the myoglobin assay and CO detection, and the results show that all of the complexes could release CO rapidly upon exposure to 365 nm UV light. Comparing their half-lives of CO release, we found that increasing the degree of unsaturation and conjugation of the ligand frame could be advantageous for prolonging the time of CO-release, and that the luminescence intensity of 1–5 could gradually be enhanced. The cellular fluorescence imaging tests demonstrate that these Mn(i) photo-CORMs can be taken up by human liver cells (HL-7702) and liver cancer cells (SK-Hep1), and exhibit good capabilities for bioimaging. A cell viability assay for SK-Hep1 shows that the anticancer activity of 3 is better than that of other complexes.

Five Mn(i) photo-activated carbon monoxide-releasing molecules were synthesized by reactions of MnBr(CO)₅ with L1–L4, and characterized via single crystal X-ray diffraction, ¹H-NMR, ¹³C-NMR, IR, UV-vis and fluorescence spectroscopy.     

Poly(3,4-ethylenedioxyselenophene): effect of solvent and electrolyte on electrodeposition,optoelectronic and electrochromic properties

In this article, we report the effect of electropolymerization conditions such as solvent and supporting electrolyte on the redox, optoelectronic and electrochromic properties of PEDOS. Monomer EDOS was synthesized by new and simple route and its electropolymerization was investigated by employing six different combinations of solvent–electrolyte namely TBAClO₄/MeCN, TBAPF₆/MeCN, TBABF₄/MeCN, TBAClO₄/PC, TBAPF₆/PC and TBABF₄/PC. Further, the electrochemical, spectroelectrochemistry, morphology and electrochromic properties of resultant PEDOS films were systematically studied. A pronounced effect of both solvent and supporting electrolyte on the electropolymerization, redox, optoelectronic and electrochromic properties on PEDOS film is noted. Among all solvent–electrolyte systems, MeCN and TBAClO₄ were found to be the most suitable medium for electropolymerization of EDOS. Further, PEDOS films prepared in PC showed red shifted absorption maxima, narrow absorption peaks in UV-vis-NIR spectra, slightly more smooth morphologies, and high optical contrasts ratio and coloration efficiency in comparison to MeCN. PEDOS films prepared in TBABF₄/PC exhibited longer λ_max (670 nm), smooth morphology, and the highest optical contrasts ratio (44.6%) and coloration efficiency (141.8 cm² C⁻¹) compared to the other solvent–electrolyte medium.

In this article, we report the effect of electropolymerization conditions such as solvent and supporting electrolyte on the redox, optoelectronic and electrochromic properties of PEDOS.