Cationic Chains Research Articles

Cationic Single-Unit Monomer Insertion (cSUMI): From Discrete Oligomers to the α-/ω-End and In-Chain Sequence-Regulated Polymers

Single-unit monomer insertion (SUMI) has become an important strategy for the synthesis of sequence-controlled vinyl polymers due to its strong versatility and high efficiency. However, all reported SUMI processes are based on a free-radical mechanism, resulting in a limited number of monomer types being applicable to SUMI or a limited number of sequences of structural units that SUMI can synthesize. Herein, we developed a novel SUMI based on a cationic mechanism (cSUMI), which operates through a degenerative (similar to radical SUMI) but cationic chain transfer process. By optimizing the chain transfer agent (CTA) and monomer pairs, a high-efficiency cSUMI was achieved for vinyl ether and styrene monomers. Based on this reaction, a range of discrete oligomers containing vinyl ether and styrene moieties, and even α-/ω-end and in-chain sequence-regulated polymers were synthesized, most of which cannot be achieved by radical SUMI. In addition, we explored the application of these sequence-regulated polymers in the preparation of miktoarm star polymers, delivery of photosensitizers, and solubilization of fluorescence probes. The development of SUMI with a new mechanism will certainly broaden the scope of structures and sequences in precise vinyl-based polymers.

Engineering hydrophilic/hydrophobic moieties of ratiometric fluorescence probe to visualize whole cytoplasmic polarity

Intracellular polarity is an essential parameter to indicate the property of microenvironment in the whole cell. The polarity is closely related to various physiological processes in different organelles and their changes in real time depending on the physiological/pathological activity. Visualization of whole cytoplasmic polarity is essential to understand the multi-organelle related pathological and biological phenomena. However, most of the reported single-organelle targeted fluorescent materials can only detect specific intracellular regions and normally with monotonic fluorescence changes. Herein, we engineered a polarity-sensitive probe 1P2N that install a cationic side alkyl chain on a push–pull type of pyrenyl-pyridium dye for whole cytoplasmic polarity visualization. Especially, this probe emits blue-green fluorescence from pyrene moiety in high-polar hydrophilic cytoplasm, while emits red fluorescence from intramolecular charge transfer process in low-polar lipidic organelles. The dual-emission response of 1P2N to polarity provides the basis for its ratiometric fluorescence monitoring of polarity changes in the whole cytoplasm under different physiological conditions. The excellent polarity-sensitive properties of probe 1P2N make it a useful tool for understanding polarity-related processes in the cytoplasmic microenvironment.

Cationic lipid-conjugated bis-arylidene oxindole derivatives as broad-spectrum breast cancer-selective therapeutics

Breast cancer is a heterogeneous malignancy with wide-ranging variations in therapeutic responses, overall survival etc. Major challenges for available chemotherapeutic agents in achieving clinical success are in maintaining systemic bio-distribution and avoiding non-specific adverse effects. Bis-arylidene oxindoles are estrogen receptor (ER)-selective bioactive molecules with moderate potency. In here, we have designed, synthesized and evaluated a series of twin aliphatic chain cationic lipid-conjugated bis-arylidene oxindole molecules with variations in nature of linker, lengths of carbon spacer and hydrophobic twin chains. We observed that among the various structural analogues, C8 twin-chain containing molecules, PGC8, S2C8 and S3C8 showed effective cancer cell-selective cytotoxicity in different cancer cell lines with an IC50 ranging from 4 to 7 µM. These molecules selectively induced apoptosis, ROS production and cell cycle inhibition at G1/S phase in ER + breast cancer cells but not in non-cancer cells. Additionally, these molecules formed homogenous self-assemblies exhibiting effective hydrodynamic diameter with positive surface charge. The self-assemblies also showed prominent cancer cell-selective uptake and DNA-binding abilities. Hence, we have shown successful incorporation of dexamethasone to the self-assemblies, and its enhanced cytotoxicity even in ER-negative breast cancer cells. All these results indicate that PGC8, S2C8 and S3C8 molecules, albeit their potent and selective ER-positive anti-breast cancer activity, can be repurposed as targeted delivery systems and hold promise as unique, broader spectrum breast cancer cell-selective therapeutic payloads.

Fast Living 3D Printing via Free Radical Promoted Cationic RAFT Polymerization.

The application of reversible deactivation radical polymerization techniques in 3D printing is emerging as a powerful method to build "living" polymer networks, which can be easily postmodified with various functionalities. However, the building speed of these systems is still limited compared to commercial systems. Herein, a digital light processing (DLP)-based 3D printing system via photoinduced free radical-promoted cationic reversible addition-fragmentation chain transfer polymerization of vinyl ethers, which can build "living" objects by a commercial DLP 3D printer at a relatively fast building speed (12.99cm h-1 ), is reported. The polymerization behavior and printing conditions are studied in detail. The livingness of the printed objects is demonstrated by spatially controlled postmodification with a fluorescent monomer.

Two Carboxylate-Cyanurates with Strong Optical Anisotropy and Large Band Gaps.

The first metal carboxylate-cyanurates, namely, K(H3C3N3O3)(HCO2) (I) and Ba2(H2C3N3O3)(CH3CO2)3(H2O) (II), which contain π-conjugated carboxylate and cyanurate groups, have been synthesized by hydrothermal methods. They crystallize in centrosymmetric space groups of P1̅ and P21/n, respectively. Compound I exhibits a novel three-dimensional (3D) structure based on a [K(H3C3N3O3)]+ cationic framework with 12-membered ring (12-MR) channels, and the (HCO2)- anions are located within the 12-MR channels. The [K(H3C3N3O3)]+ cationic framework is composed of K+ ions interconnected by H3C3N3O3 ligands. Compound II features a 3D network formed by [Ba2(CH3CO2)3]+ cationic double chains bridged by (H2C3N3O3)- anions. The [Ba2(CH3CO2)3]+ cationic double chain is composed of (CH3CO2)- anions and Ba2+ ions. Optical property measurements show that both compounds exhibit short ultraviolet cutoff edges (I, 208 nm; II, 218 nm) and wide band gaps (I, 5.43 eV; II, 5.20 eV). Importantly, K(H3C3N3O3)(HCO2) (I) features a large birefringence of 0.285@532 nm due to the parallel alignment of π-conjugated H3C3N3O3 and (HCO2)- groups, indicating that K(H3C3N3O3)(HCO2) (I) is a promising short-wave ultraviolet birefringent material. Detailed theoretical calculations elucidate that their excellent optical properties originate from the synergetic effect of both types of π-conjugated groups.

Organic-inorganic hybrid hexa-chlorido-stannate(IV) with 2-methyl-imidazo[1,5-a]pyridin-2-ium cation.

The hybrid salt bis-(2-methyl-imidazo[1,5-a]pyridin-2-ium) hexa-chlorido-stannate(IV), (C8H9N2)2[SnCl6], crystallizes in the monoclinic space group P21/n with the asymmetric unit containing an Sn0.5Cl3 fragment (Sn site symmetry ) and one organic cation. The five- and six-membered rings in the cation are nearly coplanar; bond lengths in the pyridinium ring of the fused core are as expected; the C-N/C bond distances in the imidazolium entity fall in the range 1.337 (5)-1.401 (5) Å. The octa-hedral SnCl6 2- dianion is almost undistorted with the Sn-Cl distances varying from 2.4255 (9) to 2.4881 (8) Å and the cis Cl-Sn-Cl angles approaching 90°. In the crystal, π-stacked chains of cations and loosely packed SnCl6 2- dianions form separate sheets alternating parallel to (101). Most of the numerous C-H⋯Cl-Sn contacts between the organic and inorganic counterparts with the H⋯Cl distances above the van der Waals contact limit of 2.85 Å are considered a result of crystal packing.

Anionic conductive group tunable amphoteric polybenzimidazole ion conductive membrane for vanadium redox flow battery

Anionic conductive group repels vanadium ions but is difficult to be incorporated into the selectively ionic conductive channels of the amphoteric ion conductive membrane with tunable ratio. Herein, the novel hydroxyl bromopropane anionic precursor side chain is proposed, in which the hydrophilic hydroxyl groups aggregate into ionic clusters with the sulfate ester cationic conductive side chains of polybenzimidazole via hydrogen bond during membrane casting. The subsequent conversion of the bromopropane precursor to quaternary ammonium can easily tune the anionic exchange capacity and integrate cations into the hydroxyl involved ionic conductive channels for selectively repelling vanadium ions. Compared with Nafion 212 membrane, the obtained amphoteric membrane exhibits much lower vanadium ion permeability (1.9 × 10−9 cm2s−1) and slightly lower area resistance (0.25 Ω cm2). Excellent performance of vanadium redox flow battery (coulombic efficiency, 99.2%, energy efficiency, 85.9% at 100 mA cm−2 and 0.31% discharge decay rate) is achieved, and efficiencies keep stable during the 500 cycles test. The performance of VRFB is surpass than that of most reported amphoteric ion conductive and Nafion 212 membranes.

Effect of ion structure on the nanostructure and electrochemistry of surface active ionic liquids.

The ion structure of surface active ionic liquids (SAILs), i.e. ion charge group and alkyl chain structure, controls their bulk and interfacial nanostructure and the electrochemical properties near an electrode. The structures in the bulk and at the interface were investigated by small and wide-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), respectively. An investigation was performed using cyclic voltammetry. All SAILs show pronounced sponge-like bulk nanostructure. For the first time, the bulk nanostructures of SAILs are found to change from anion bilayer structures to cation-anion interdigitated structures as the ion structures change from short alkyl chain cations and linear alkyl chain anions to long alkyl chain cations and branched alkyl chain anions. The bulk nanostructure packs more compactly at a higher temperature, likely due to the conformational change and enhanced interdigitations of alkyl chains. The thicknesses of SAIL interfacial layers align with the repeat distances of the bulk nanostructure, similar to conventional ILs with long cation alkyl chains. All SAILs have wide electrochemical windows >4V, which are not affected by the alkyl chain structure and cation charge groups.

CPL-active water-soluble aromatic oligoamide foldamers.

A series of enantiopure water-soluble quinoline-based foldamers were prepared and their optical and chiroptical properties in water were investigated. The new hexameric sequences incorporated either cationic or anionic water-solubilizing chains, and one of the oligomers was additionally functionalized by an electron donating moiety to further modulate the optoelectronic properties. A systematic study revealed strong electronic circular dichroism and circularly-polarized luminescence properties in water, with dissymmetry factors up to 2 × 10-2 in absorption and 5 × 10-3 in emission, regardless of the nature of the solubilizing chains and functions. This study therefore highlights new opportunities for the development of water-soluble and chiroptically-active artificial systems towards chirality-associated applications in aqueous or biological media.

Phase coexistence in [C22/C1MIm]+[NO3]- ionic-liquid mixtures and first-order phase transitions from homogeneous liquid to smectic B by varying the cation ratio.

We perform molecular dynamics simulations to investigate the transition processes of [C22/C1MIm]+[NO3]- binary mixtures by varying the cation ratio of C22 to C1 at a fixed temperature of 400 K. The cation ratio is tuned by ranging C22 percentage from 0% to 100% with a fixed number of 4096 total simulated ion pairs. Our simulated-annealing results indicate that, at 400 K, pure C1 is a homogeneous liquid whilst pure C22 is an ionic liquid crystal (ILC) of smectic-B (SmB) type. With increasing C22 percentage, the system goes through a first-order phase transition from homogeneous liquid to nano-fragment liquid in the range from 15% to 17.5%, during which some of the individual cationic alkyl side chains locally aggregate to form small bundles "floating" in the polar "solvent" composed of anions and cationic head groups. Although the side chains in each bundle are parallelly aligned, the bundles distribute randomly without a global orientation. As the C22 percentage further increases, another first-order phase transition occurs to bring the system into the SmB ILC phase. Particularly, when the C22 percentage is in the range from 45% to 50%, the SmB phase coexists with the liquid phase containing both individual and bundled alkyl side chains.

Tracing the Effect of Replacing [Gly]- with [Ala]- and Hydroxylation of [emim]+ on the Fine-Tuning of the Transport Properties of the Corresponding Amino Acid-Based Ionic Liquids Using MD Simulation.

Natural amino acid-based ionic liquids (AAILs) composed of deprotonated amino acids, [AA]-, as anions and hydroxylated imidazolium cations provide an eco-friendly nontoxic IL family with the growing number of chemical and biochemical revolutionary applications. In this paper, the transport properties of four AAILs composed of 1-(2-hydroxyethyl)-3-methylimidazolium ([HOemim]+) and 1-ethyl-3-methylimidazolium ([emim]+) cations with alaninate and glycinate anions were studied by molecular dynamics (MD) simulations. A nonpolarizable all-atom force field with the scaled charge (±0.8e) on each of the ions was applied and compared with the unit charge model in some cases. The tunable effects of the presence of the hydroxyl group in the side chain of the imidazolium cation, the type of amino acid anion, and the varied temperature on the dynamical behavior of AAILs were investigated in detail. The experimentally compatible trends of the simulated ionic self-diffusion coefficients, ionic conductivity, and ionicity were found to be inverse to the viscosity and ionic association of these ILs as [emim][Gly] > [emim][Ala] > [HOemim][Gly] > [HOemim][Ala]. The main reason behind these trends is the higher ability of the hydroxylated cation for the hydrogen-bond formation with [AA]-. The mean square displacement (MSD), self-diffusion, and transference number of imidazolium cations are larger than those of [AA]- anions, except in the case of [HOemim][Gly]. It was found that the activation energy for diffusion of [AA]- is lower than that of [HOemim]+ but higher than that of [emim]+ in [HOemim][AA] and [emim][AA] ILs, respectively. The computed velocity autocorrelation function (VACF) showed that [Gly]-, as the lightest ion, has the shortest mean collision time and velocity randomization time among the ions, especially in the [HOemim][Gly] IL. Replacing [emim]+ with [HOemim]+, similar to the effect of decreasing temperature, causes significant decreasing of the ionic self-diffusion and increasing of the well depth of the first minimum of the ionic VACFs. Current findings show that introducing suitable functional groups in the side chain of imidazolium cations can be a viable approach for efficient engineering design and fine-tuning of the transport properties of these AAILs.

Selective separation of Nd from La/Ce/Pr using phosphate-based ionic liquids: Solvent extraction studies and density functional theory

Since neodymium (Nd) has similar physicochemical properties to lanthanum (La), cerium (Ce) and praseodymium (Pr), their efficient separation and purification is very difficult. Three new phosphate-based ionic liquids (ILs): N,N-dimethyloctylamine bis(2-ethylhexyl)phosphate ([N1,1,8,H][DEHP]), N,N-dimethyldecylamine bis(2-ethylhexyl)phosphate ([N1,1,10,H][DEHP]), N,N-dimethyldodecylamine bis(2-ethylhexyl)phosphate ([N1,1,12,H][DEHP]) were synthesized and evaluated for selective separation of Nd(III) from aqueous solution. The influences concentration of Nd(III), phase volume ratio (O/A), cation chain length of ILs, extraction time, extraction temperature, salt concentration, solution acidity have on the performance of ILs for extraction separation of Nd(III) from aqueous solution were systematically investigated. It was found that the extraction efficiency (E) of Nd(III) using [N1,1,8,H][DEHP] was close to 100% at pH of 4, and that it only required 10 min to reach extraction equilibrium at 303 K. Meanwhile, the separation factors (β) values of βNd/La, βNd/Ce, βNd/pr using [N1,1,8,H][DEHP] were all higher than 3. The density functional theory (DFT) results indicated that the interaction between [N1,1,8,H][DEHP] and Nd were stronger than that between La, Ce and Pr. In addition, almost 100% of Nd(III) could be recycled from the loaded [N1,1,8,H][DEHP] phase using 0.16 mol·L−1 hydrochloric acid via one step, and the E of Nd(III) by regenerated [N1,1,8,H][DEHP] remained about 97% after eight cycles. Moreover, the extraction mechanism of Nd(III) using [N1,1,8,H][DEHP] was complexation mechanism based on infrared spectroscopy and slope analysis. This work furnishes a strategy for selective separation of Nd(III) using phosphate-based ILs without diluent.

Experimental and Theoretical Studies of the Corrosion Inhibition Performance of Fatty Acid-based Ionic Liquids for Mild Steel in 1 M HCl: Effects of the Varied Alkyl Chain Length in the Anionic Group

Five fatty acid-based ionic liquids (FAILs) with various anionic alkyl chain lengths are synthesized, namely methyltrioctylammonium butyrate ([N8881][C4:0]), methyltrioctylammonium caproate ([N8881][C6:0]), methyltrioctylammonium octanoate ([N8881][C8:0]), methyltrioctylammonium laurate ([N8881][C12:0]), and methyltrioctylammonium palmitate ([N8881][C16:0]), to investigate the potential effects of anionic alkyl chains on their corrosion inhibition property for mild steel in 1 M HCl solution via X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle measurements, electrochemical measurements, and weight loss measurements. The results reflect that the FAIL inhibitor can adsorb on the surface of mild steel to form a protective film and effectively inhibit the corrosion. [N8881][C8:0] exhibits the optimal inhibition efficiency (96.94%) in comparison to [N8881][C4:0] (80.73%), [N8881][C6:0] (89.34%), [N8881][C12:0] (90.69%), and [N8881][C16:0] (74.42%). It is speculated that the varied anionic alkyl chain length may change the intensity of the protective film to affect the inhibition efficiency. The in-depth analysis by molecular dynamic simulation confirms that [N8881][C8:0] with the same anionic and cationic alkyl chain lengths shows the most ordered and compact film on the mild steel surface. The present study focuses on the effects of the anionic alkyl chain on the corrosion inhibition performance and provides novel insights into the design and development of effective and eco-friendly ionic liquids as corrosion inhibitors.

Study on the epoxidation of olefins with H2O2 catalyzed by biquaternary ammonium phosphotungstic acid

Selective epoxidation of olefins is an important field in chemical industry. In this work, we developed a new phosphotungstic acid catalyst {[(C8H17)(CH3)2N]2(CH2)3}1.5{PO4[WO(O2)2]4} with long carbon chain and biquaternary ammonium cation. Cyclohexene could be epoxidized to cyclohexene oxide in 96.3% conversion and 98.2% selectivity. The catalyst type, solvent type, catalyst loading, initial molar ratio, temperature, cycle performance and substrate extensibility were studied and optimized, the kinetic parameters about overall reaction and unit reaction were also calculated. Dynamic light scattering analysis was carried out to explain the different catalytic performance between catalysts with different carbon chain length. This novel catalyst and the corresponding dynamics and mechanism study could probably help the industrial application on the epoxidation of cyclohexene with H2O2.

Humidity Sensors Based on Magnetic Ionic Liquids Blended in Poly(vinylidene fluoride-co-hexafluoropropylene)

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films incorporating 40 wt % of different types of imidazolium ionic liquids (ILs) comprising different magnetic anions (tetrachloroferrate [FeCl4]−, tetrathiocyanatocobaltate [Co(SCN)4]2–, and tetrachlorocobaltate [CoCl4]2−) and imidazolium cation chain lengths (1-butyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium) have been developed for humidity-sensing applications. The influence of the different ILs on the morphology of the IL/PVDF-HFP composites has been evaluated, with a porous structure observed independently of the IL anion type and cation chain length. The inclusion of the ILs into PVDF-HFP induces polymer crystallization into the electroactive β phase, with the increase more noticeable for PVDF-HFP/[Bmim][FeCl4], which reaches a β phase content of 85%. The degree of crystallinity slightly decreases with the incorporation of the filler and the incorporation of [Bmim]2[CoCl4], [Bmim]2[Co(SCN)4], and [Emim]2[Co(SCN)4], leading to a degree of crystallinity between 11 and 13%. A decrease in the thermal stability and yield strength is observed in the hybrid samples with respect to neat PVDF-HFP, with this decrease being more noticeable for the PVDF-HFP/[Bmim]2[Co(SCN)4] samples. Further, the highest magnetization has been obtained for the PVDF-HFP/[Bmim]2[Co(SCN)4] and PVDF-HFP/[Bmim][FeCl4] composites with similar filler concentrations. The suitability of the developed materials for humidity sensing has been evaluated by analyzing the impedance variation with varying relative humidity from 30 to 85%. [Bmim]2[CoCl4]/PVDF-HFP displays the highest relative humidity (RH) sensing response of −2245 ± 240 Ω/RH. Finally, the applicability of the developed hybrid IL/polymer composites has been demonstrated by the development of a real-time breathing monitoring device.

Multi‐Stimuli Responsive Thiazolothiazole Viologen‐Containing Poly(2‐Isopropyl‐2‐Oxazoline) and Its Multi‐Modal Thermochromism, Photochromism, Electrochromism, and Solvatofluorochromism Applications

AbstractSmart materials are highly desirable over the recent decade due to the growing demand on complicated nature. Smart materials with stable stimuli‐responsive properties are widely applied in sensors, smart windows, displays, and chemical valves, but they are relatively rare. Most of the current chromic materials are triggered by one or two external stimuli, and only a few multi‐stimuli responsive instances still suffer by their restricting functional states, such as solution or polymer. To address these challenges, researchers are focusing their efforts on developing a new generation of multi‐stimulus responsive chromic materials. In this article, our group has adopted a new strategy for the synthesis of the multi‐stimuli responsive single polymeric material, which can be useful for different applications (such as thermochromism, photochromism, electrochromism, and solvatofluorochromism). Thiazolothiazole viologen (TTv)‐containing poly(2‐isopropyl‐2‐oxazoline) (PiPO) was synthesized using a one‐pot reaction where the living cationic polymer chains were reacted with thiazolothiazole viologen to produce multi‐stimuli responsive PiPO‐TTv. PiPO‐TTv‐based device demonstrated multi‐responsive properties due to the thermoresponsive properties of PiPO segments and photo‐, electro‐responsive properties of TTv monomer, respectively. PiPO‐TTv material, additionally exhibits fluorescence characteristics that makes it appealing for environmental and molecular biological sensor applications.

Boosting Type-I and Type-II ROS Production of Water-Soluble Porphyrin for Efficient Hypoxic Tumor Therapy.

As the most successful clinically approved photosensitizers, porphyrins have been extensively employed in the photodynamic therapy (PDT) of cancers. However, their poor water solubility, aggregation-induced self-quenching on ROS generation, and a low tolerance for a hypoxic condition usually result in unsatisfied therapeutic outcomes. Therefore, great efforts have been dedicated to improving the PDT efficacy of porphyrin-type photosensitizers in treating hypoxic tumors, including combination with additional active components or therapies, which can significantly complicate the therapeutic process. Herein, we report a novel water-soluble porphyrin with O-linked cationic side chains, which exhibits good water solubility, high photostability, and significantly enhanced ROS generation efficacy in both type-I and type-II photodynamic pathways. We have also found that the end charges of side chains can dramatically affect the ROS generation of the porphyrin. The cationic porphyrin exhibited high in vitro PDT efficacy with low IC50 values both in normoxia and hypoxia. Hence, during in vivo PDT study, the cationic porphyrin displayed highly effective tumor ablation capability. This study demonstrates the power of side-chain chemistry in tuning the photodynamic property of porphyrin, which offers a new effective strategy to enhance the anticancer performance of photosensitizers for fulfilling the increasing demands for cancer therapy in clinics.

Zwitterion coordination to hard cations: Synthesis and characterization of betaine coordination compounds with divalent Mg, Ca, Sr and Ba and of trivalent Y, La and Pr

We report the synthesis and structure of coordination compounds in which betaine acts as a ligand towards Pearson-hard cations. The overall neutral zwitterion was reacted with the corresponding nitrate salts in polar protic solvents such as water or methanol or mechanochemically by grinding the reaction partners. Reaction of MgII, CaII, SrII and BaII resulted in the first alkaline earth derivatives of betaine. The products comprise mono- and oligonuclear cations for the light, and cationic chain polymers for the heavy group2 metals. In the case of CaII, the betaine stoichiometry was decisive for the outcome of the reaction; solids with 1:4 and the less intuitive 3:16 cation to ligand ratio have been structurally characterized. Coordination numbers increase from six for MgII and CaII over seven and eight for the two independent SrII to eight for BaII cations. Coordination of betaine to trivalent Y, La and Pr results in the formation of structurally related dinuclear cations, with coordination numbers eight for Y and nine for the larger lanthanides. Water and betaine compete for coordination; aqua ligands prevail for the smaller, betaine for the larger cations. Betaine coordination to all these hard cations occurs in various modes, similar to those of other carboxylates. Bridging betaine subtends cation⋯cation distances between 4.5 and 6.1 Å. Nitrate coordination was only observed in the BaII chain polymer.

Synthesis of novel heterogeneous photocatalysts based on Rose Bengal for effective wastewater disinfection and decontamination

Anionic photosensitizers such as rose Bengal (RB) exhibit low efficiency in the photoinactivation of Gram-negative bacteria. Different strategies have been developed to improve their efficiency being the most effective the addition of the photosensitizer to organic cationic materials. In this context, we have designed the synthesis of a novel heterogeneous photocatalyst based on silica in which the oxidizing properties of singlet oxygen photogenerated by RB have been combined with the chemoattraction of the bacteria to the cationic chains and their biocidal action. Thus, RB and cationic chains have been covalently linked to glass wool to obtain a photocatalyst that showed a highly efficient photodynamic activity against the Gram-positive (Enterococcus faecalis) and Gram-negative (Escherichia coli) bacteria. In addition, the new heterogeneous photocatalyst also resulted to be efficient in the decontamination of drugs such as diclofenac under visible light irradiation.

Low-Dimensional Magnetism in Multivariate Copper/Zinc MOF-74 Materials Formed via Different Mechanochemical Methods.

MOF-74 is an archetypal magnetic metal-organic framework (MOF) family, with metal nodes bridged by 2,5-dioxido-1,4-benzenedicarboxylic acid (H4dobdc) and arranged into one of the simplest representations of the 1D Ising magnetic model. Recently, a novel mechano-synthetic approach opened a pathway toward a series of bimetallic multivariate (1:1) M1M2-MOF-74 materials, with the uniform distribution of metal cations in the oxometallic chains, offering a unique opportunity to investigate low-dimensional magnetism in these heterometallic MOFs. We explore here how different mechanochemical procedures affect the interaction between the metal nodes of the model system of three multivariate copper(II)/zinc(II)-MOF-74 materials, two of which were obtained through a template-controlled procedure, and the third one was obtained by recently developed mechanical MOF-alloying combined with subsequent accelerated aging. While the three Cu/Zn-MOF-74 products have almost identical powder X-ray diffraction (PXRD) diffractograms and Fourier transform infrared spectra, they differ significantly in their magnetic properties, as revealed through detailed magnetization and X-band and multifrequency high-field electron spin resonance measurements. The magnetic results of the three multivariate Cu/Zn-MOF-74s were compared to the properties of the monometallic Cu-MOF-74, which shows antiferromagnetic intrachain and weaker ferromagnetic interchain interactions. Energy-dispersive X-ray spectroscopy/scanning electron microscopy and solid-state nuclear magnetic resonance spectroscopy helped rationalize the observed differences in magnetization, and in situ synchrotron PXRD monitoring of template-controlled MOF formation revealed different reaction pathways when using the zinc or copper intermediates, involving even the fleeting occurrence of a rare MOF-74 polymorph.