Multi-functional zwitterionic compounds as additives for lithium battery electrolytes

A series of multi-functional zwitterionic compounds having both ester and sulfonate groups were synthesized and their electrochemical properties were investigated. The effect of added zwitterionic compounds on the cycling performance of the cell containing 1 M LiPF₆ in EC, DMC, and EMC (1/1/1 by vol.) was also examined. The cell capacity was not varied much at 1/5 C up to 50 cycles with the addition of either 2.25 wt% N-methylpyrrolidinium-N-(propyl sulfonate) (MePyS) or N-methylpiperidinium-N-(propyl sulfonate) (MePipS) as an additive, but dropped significantly at higher C rate of 1 C. Such a sharp decrease of the performance at higher C rate was not observed when MePyS or MePipS was replaced by N-(2-acetoxyethyl) pyrrolidinium-N-(propyl sulfonate) (EsPyS) or N-(2-acetoxyethyl) piperidinium-N-(propyl sulfonate) (EsPipS), implying the positive role of the ester functional group.FT-IR study clearly demonstrates that ester-containing zwitterionic compounds are able to interact with Li⁺ ions through both sulfonate and ester functional groups.     

Mn,B, N co-doped graphene quantum dots for fluorescence sensing and biological imaging

The fluorescent and quantum yield (QY) of graphene quantum dots has been improved in recent years by doped atoms, which have good application prospects in fluorescence sensors and biological imaging. Here, a one-step hydrothermal synthesis method was used to synthesize manganese ions bonded with boron and nitrogen-doped graphene quantum dots (Mn-BN-GQDs). Compared with the boron and nitrogen co-doping graphene quantum dots (BN-GQDs), the fluorescence properties and quantum yield of Mn-BN-GQDs are significantly improved. Meanwhile, Mn-BN-GQDs exhibit low toxicity and good fluorescence imaging in living cells and has high selectivity to Fe³⁺ ions. Therefore, this experiment design Mn-BN-GQDs as a fluorescence sensor to detect Fe³⁺ ions, providing strong evidence for the advanced high sensitivity, selectivity and wide detection range of the Mn-BN-GQDs as a fluorescence sensor. These results indicate a dual linear relationship with good linear relationships in the 10–100 μM and 100–800 μM ranges, and limit of detection are 0.78 μM and 9.08 μM, respectively. Cellular imaging results demonstrate that Mn-BN-GQDs can be used as fluorescence sensors in biological imaging. Mn-BN-GQDs can be used for fluorescence sensing in biological imaging in combination with low toxicity, QY and quantum dot lifetime.     

Photophysics and Intracellular Distribution of a Boronated Porphyrin Phototherapeutic Agent

Abstract— The absorption and emission spectra, fluorescence quantum yields and lifetimes and triplet state properties of a boronated porphyrin, the tetrakiscarborane carboxylate ester of 2,4-(α,β-dihydroxyethyl) deuteroporphyrin IX (BOPP), have been determined. This compound is an alternative photodynamic therapy (PDT) agent that exhibits highly selective tumor localization, with the potential to be used in conjunction with boron neutron capture therapy. The photophysical characteristics of BOPP are similar to other porphyrins and it exhibits marked aggregation and acid-base speciation under typical physiological conditions. In particular, protonation of the porphyrin imino (-N=) nitrogens occurs in the pH 5–7 region and influences the photophysical properties. Time-resolved confocal fluorescence imaging of the intracellular distribution of BOPP in C6 glioma cells indicates distinct subcellular localization and heterogeneity of emission. The results are interpreted and discussed in terms of the possible mechanisms for cellular uptake and localization.     

Pyrroles and related compounds—XXXV: A stepwise,general synthesis of unsymmetrically substituted porphyrins

Using a new, general approach involving the stepwise progression through pyrrole, dipyrrole, tripyrrole, to tetrapyrrole, followed by cyclisation of the resulting a,c-biladiene by the copper salt method, syntheses of isocoproporphyrin tetramethyl ester (1b), coproporphyrin-III tetramethyl ester (24), protoporphyrin-IX dimethyl ester (26), 2,4,6,7-tetrakis (2-methoxycarbonylethyl)-5-methoxycarbonylmethyl-1,3,8-trimethylporphin (29) (the ester of the pentacarboxylic porphyrin recently associated with haem metabolism), rhodoporphyrin-XV dimethyl ester (27) and 2,4,7-triethyl-6-methoxycarbonyl-1,3,5,8-tetramethylporphin (28), are described.The route employs condensation of unsymmetrically substituted pyrromethanes with 2-formyl-5-methylpyrroles to give crystalline and fully characterised tripyrrene salts in high yield. These are then condensed with a second mole of a different 2-formyl-5-methylpyrrole to give very high yields of a,c-biladiene dihydrobromides; cyclisation with copper(II) chloride indimethylformamide gives copper(II) porphyrins which are demetallated in trifluoroacetic acid containing sulphuric acid to give high overall yields of the corresponding metal free porphyrins.     

Photophysical,photochemical and electrochemical properties of water soluble silicon,titanium and zinc phthalocyanines

The photophysical, and photochemical properties of titanium, silicon and zinc octacarboxy phthalocyanine (OTiOCPc, (OH)₂SiOCPc and ZnOCPc) and their tetrasulfonated counterparts (OTiTSPc, (OH)₂SiTSPc and ZnTSPc) in phosphate-buffer solution (PBS), pH 10 were studied. The tetrasulfonated derivatives were also studied in the presence of a surfactant, cremophore EL (CEL) due to their high aggregation tendency in aqueous solutions. Triplet quantum yields ranged from 0.20 to 0.48 for MOCPcs and 0.32–0.65 for MTSPcs in the presence of CEL and in pH 10. High triplet lifetimes were observed for ZnTSPc (270 μs, in the presence of CEL) or ZnOCPc (130 μs) compared to values ranging from 50 to 70 μs for the rest of the complexes.     

Porphyrins with exocyclic rings. Part 20: Synthesis and spectroscopic characterization of porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole moieties

Porphyrins with fused 2,1,3-benzoxadiazole and 2,1,3-benzoselenadiazole units were prepared by the ‘3+1’ MacDonald-type methodology. 4-Nitro-2,1,3-benzoxadiazole, 6-chloro-4-nitro-2,1,3-benzoxadiazole and 4-nitro-2,1,3-benzoselenadiazole condensed with isocyanoacetates in the presence of the non-nucleophilic base DBU to give tricyclic pyrrole derivatives in excellent yields. Further cleavage of the ester moieties and decarboxylation afforded α-unsubstituted pyrroles and these were further condensed with 2 equiv of an acetoxymethylpyrrole tert-butyl ester to give crude preparations of tripyrranes. The tert-butyl ester protective groups were cleaved with TFA and following dilution with dichloromethane, ‘3+1’ condensation with a pyrrole dialdehyde, and oxidation with ferric chloride, the heterocyclic ring fused porphyrins were obtained in moderate yields. The yields were lower than expected because of difficulties in preparing required tripyrranes due to the reduced reactivity of the pyrrolic intermediates. The UV-vis spectra of these new porphyrin systems were highly modified showing broadened split Soret bands. In addition, the nickel(II), copper(II) and zinc complexes gave unusual UV-vis spectra with weakened split Soret bands and strong Q-type absorptions above 600 nm. These modified structures show some potential for applications as photosensitizers in photodynamic therapy.     

Molecular structures and mixed spin states of chloroiron(III) complexes of the 2,3-diethyl-(detpp), 2,3,7,8-tetraethyl-(cis-tetpp), 2,3,12,13-tetraethyl-(trans-tetpp) and 2,3,7,8,12,13-hexaethyl-(hetpp) 5,10,15,20-tetraphenylporphyrin complexes

The chloroiron(III) complexes of the partially peripherally crowded 2,3-diethyl-2,3,12,13-tetraethyl-, 2,3,7,8-tetraethyl-, and 2,3,7,8,12,13-hexaethyl-5,10,15,20-tetraphenylporphyrins have been synthesised and their X-ray structures have been determined. The porphyrins present in these molecules are non-planar and assume asymmetric predominately saddle shapes. They are also slightly ruffled and domed according to an analysis of the out-of-plane distortions performed by using normal-coordinate structural decomposition (NSD). The saddle deformations, dominant in these chloroiron(III) complexes, are larger than those observed in all the cytochromes c’, whose structures were analysed by this method. Despite the large saddle-shaped distortions of the porphyrins present in these species, the quantum mechanical S = 3/2 spin admixtures into the S = 5/2 high-spin state (QMS state) observed are small. The EPR spectra of these C_β-ethyl-substituted tetraphenylporphyrin complexes indicate S = 3/2 admixtures of 0% in Fe(detpp)Cl (1), 0.75% in Fe(trans-tetpp)Cl (2), 1.20% in Fe(cis-tetpp)Cl (3) and 2.75% in Fe(hetpp)Cl (4). The large saddle distortions of the porphyrins present in these compounds and the small S = 5/2,3/2 spin admixtures found indicate that the saddle distortions alone are probably not sufficient to cause the QMS states observed in several ferricytochromes c’ isolated from photosynthetic bacteria and in plant peroxidases.     

Electrochemical reduction of dehydroamino acids: synthesis and photophysical properties of β,β-diarylalanines

Several β,β-disubstituted dehydroalanines were prepared from β,β-dibromo or β-bromo, β-substituted dehydroalanines and aryl boronic acids using a Suzuki-Miyaura cross-coupling reaction. The electrochemical behaviour of these compounds was studied by cyclic voltammetry. All compounds studied showed similar reduction potentials and these were similar to the peak potential of the methyl ester of N-tert-butoxycarbonyl dehydrophenylalanine. Thus, the presence of a second aryl moiety in the dehydroalanine scaffold does not significantly change the reduction potential.Controlled potential electrolyses were performed at the cathodic peak potential in the presence of triethylammonium chloride as proton donor. The only products isolated in good to high yields were the corresponding β,β-diarylalanines. This reaction was also carried out using a dipeptide containing a β,β-diaryldehydroalanine to give a 1:1 diastereomeric mixture of the reduction product.The photophysical properties of two of the β,β-diaryldehydroalanines and of the corresponding β,β-diarylalanines were studied in three solvents of different polarity. The β,β-diaryldehydroalanines show low fluorescent quantum yields (Φ_F<9%) due to the conjugation of the aromatic moieties with the α,β-double bond and with the carbonyl group, which favours the non-radiative deactivation pathways. The absence of conjugation in the reduction products leads to a significant increase in the fluorescence quantum yields. These results show that the β,β-disubstituted alanines could be used as fluorescent markers.     

A simple,fast and low-cost turn-on fluorescence method for dopamine detection using in situ reaction

A simple, fast and low-cost method for dopamine (DA) detection based on turn-on fluorescence using resorcinol is developed. The rapid reaction between resorcinol and DA allows the detection to be performed within 5 min, and the reaction product (azamonardine) with high quantum yield generates strong fluorescence signal for sensitive optical detection. The detection exhibits a high sensitivity to DA with a wide linear range of 10 nM–20 μM and the limit of detection is estimated to be 1.8 nM (S/N = 3). This approach has been successfully applied to determine DA concentrations in human urine samples with satisfactory quantitative recovery of 97.84%–103.50%, which shows great potential in clinical diagnosis.     

Perylen-3-ylmethyl: fluorescent photoremovable protecting group (FPRPG) for carboxylic acids and alcohols

Perylen-3-ylmethyl demonstrated as a new fluorescent photoremovable protecting group (FPRPG) for carboxylic acids and alcohols. Carboxylic acids including amino acids were protected as their corresponding esters by coupling with FPRPG, perylen-3-ylmethyl. Photophysical studies of caged esters showed that they all exhibited strong fluorescence properties and their fluorescence quantum yields were in the range of 0.85–0.95. Irradiation of the caged esters using visible light (≥410 nm) in aqueous acetonitrile released the corresponding carboxylic acids in high chemical (94–97%) and quantum (0.072–0.093) yields. The results obtained from the photolysis of the caged ester in different solvents indicated that solvent has influence on the rate of photorelease. Further, we also explored the ability of FPRPG, perylen-3-ylmethyl for the protection of alcohols and phenols.     

Synthesis and characterization of oxadisilole-fused acridines,dioxatrisilole-fused acridines and benzo[b]acridines

Oxadisilole-fused acridines, dioxatrisilole-fused acridines and benzo[b]acridines were synthesized through nucleophilic additions and aromatization reactions of arynes with 2-aminoaryl ketones or 2-aminoaryl aldehydes in good yields at room temperature. The photophysical, redox and thermal properties of these compounds were characterized. These compounds show potential applications as strong deep-blue or green emitters for OLED because of high fluorescence quantum yields and good thermal stabilities.     

Carboxyphenyl metalloporphyrins as photosensitizers of semiconductor film electrodes. A study of the effect of different central metals

Free-base (P), Zn(II) (P(Zn)), Cu(II) (P(Cu)), Pd(II) (P(Pd)), Ni(II) (P(Ni)), and Co(II) (P(Co)) 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl) porphyrins were designed and synthesized to be employed as spectral senzitizers in photoelectrochemical cells. The dyes were studied adsorbed on SnO(2) nanocrystalline semiconductor and also in Langmuir-Blodgett film ITO electrodes in order to disclose the effect of molecular packing on the studied properties. Electron injection yields were obtained by fluorescence quenching analysis comparing with the dyes adsorbed on a SiO(2) nanocrystalline insulator. Back electron-transfer kinetics were measured by using laser flash photolysis. The unmetallized and metallized molecules have different singlet state energies, fluorescence quantum yields, and redox properties. The quantum yields of sensitized photocurrent generation are shown to be highly dependent on the identity of the central metal. It is shown that P(Ni) and P(Co) do not present a photoelectric effect. The other porhyrins present reproducible photocurrent, P(Pd) being the one that gives the highest quantum yield even in closely packet ITO/LB films. Photocurrent quantum yields increase as the dye ground-state oxidation potential becomes more anodic, which is in agreement with the observation, obtained by laser flash photolysis, that back electron-transfer kinetics decrease with the increase in the driving force for the recombination process. This effect could be exploited as a design element in the development of new and better sensitizers for high-efficiency solar cells involving porphyrins and related dyes.     

Sulfamide-substituted-BODIPY based fluorescence drugs: Synthesis,spectral characteristics,molecular docking,and bioactivity

BODIPY derivatives have attracted much attention in the field of biological probes, but probes with a single imaging function are no longer innovative. In this paper, two multifunctional sulfonamide-BODIPY derivatives were designed and synthesized. Photophysical properties, cytotoxicity, in vitro and in vivo imaging, apoptosis, cell cycle, and molecular docking simulation were studied. The results showed that the compound had low cytotoxicity to normal cells, but had strong inhibitory effect on tumor cells. The IC₅₀ value of compound 3 on HCT-116 cells was 58.61 ± 4.91 μmol/L, and 4 on HeLa cells was 52.29 ± 10.93 μmol/L. Cell imaging and mice experiments demonstrated that the probe had excellent biocompatibility and potential tumor targeting; and in vivo imaging of mice at different time periods showed that the fluorescence intensity of probes in subcutaneous lung tumor gradually increased with the extension of time. In addition, the flow cytometry analysis of 3 showed that the G1 phase of HCT-116 cells was inhibited and apoptosis of tumor cells was promoted. In molecular docking simulation, sulfonamide-BODIPY derivatives had high affinity scores with CDK2: −8.0 and −8.4 kcal·mol⁻¹, and the multiple interactions with receptors provided conditions for the probes to recognize tumor cells.     

Multifunctional red phosphorescent bis-cyclometallated iridium complexes based on 2-phenyl-1,2,3-benzotriazole ligand and carbazolyl moieties

Multifunctional phosphorescent bis-cyclometallated iridium(III) complexes based on the 2-phenyl-1,2,3-benzotriazole moiety and bearing branched hole-transporting carbazole fragments were synthesized. The isolated compounds were found to be amorphous and expressed very good solubility. Introduction of flexible aliphatic chains of various lengths into the iridium complexes enabled manipulation of their glass transition temperature. The iridium complexes exhibited red phosphorescence emission at 650 nm with the lifetime of 5.7 μs and phosphorescence quantum yields of 0.22 and 0.17 in solution and solid state, respectively, at room temperature. The shielding effect of the carbazolyl moieties on the concentration quenching of phosphorescence of the iridium centers was found to result in the increased excited state lifetime and quantum yield due to the suppressed exciton migration. Non-optimized OLED devices, based on the phosphorescent bis-cyclometallated iridium(III) complex without host material were fabricated and their electroluminescence properties were evaluated.     

Chemical composition,antioxidant, antimicrobial and antiproliferative activity of Laureliopsis philippiana essential oil of Chile,study in vitro and in silico

Chilean Laureliopsis philippiana has been used in traditional medicine by the Mapuche and their ancestors. To evaluate its pharmacological activity, Laureliopsis philippiana leaf essential oil extract (LP_EO) was chemically and biologically characterized in the present study. In vitro antioxidant potential was analyzed, and antitumor activity was evaluated in non-tumor and tumor cell culture lines. Caenorhabditis elegans was used as a model for evaluating toxicity, and the chemical composition of the essential oil was analyzed using gas chromatography–mass spectrometry. The oil contains six major monoterpenes: eucalyptol (27.7 %), linalool (27.6 %), isozaphrol (19.5 %), isohomogenol (12.6 %), α-terpineol (7.7 %), and eudesmol (4.8 %). Based on quantum mechanical calculations, isosafrole and isohomogenol conferred in vitro antioxidant and antimicrobial activity to LP_EO. In addition, LP_EO showed antimicrobial activity against clinical Helicobacter pylori isolates (MIC 64 and MBC > 128 μg·mL^?1), Staphylococcus aureus (MIC 32 and MBC > 64 μg·mL^?1), Escherichia coli (MIC 8 and MBC 16 μg·mL^?1) and Candida albicans (MIC 64 and > 128 μg·mL^?1). LP_EO could selectively inhibit the proliferation of epithelial tumor cell lines but showed low toxicity against Caenorhabditis elegans (0.39 to 1.56 μg·mL^?1). Therefore, LP_EO may be used as a source of bioactive compounds in novel pharmacological treatments for veterinary and human application, cosmetics, or sanitation.     

Chemo-enzymatic synthesis of both enantiomers of rugulactone

The synthesis of both the (R)- and (S)-enantiomers of the natural product rugulactone has been achieved. Candida rugosa lipase hydrolyzes the butyrate ester of the protected 3-hydroxy homoallylic alcohol with very high enantioselectivity (E = 244) and provides the key intermediates with high enantiomeric purity (ee 98–99%) and excellent yields.     

Synthesis,photophysical and photochemical properties of tetra- and octa-substituted gallium and indium phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-[4-(benzyloxyphenoxy)] substituted gallium(III) and indium(III) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, ¹H NMR spectroscopy and electronic spectroscopy. General trends are described for quantum yields of photodegredation, fluorescence quantum yields and lifetimes, triplet lifetimes and triplet quantum yields as well as singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO). Substituted indium phthalocyanine complexes (7b–9b) showed much higher quantum yields of triplet state and shorter triplet lifetimes, compared to the substituted GaPc derivatives due to enhanced intersystem crossing (ISC) in the former. The gallium and indium phthalocyanine complexes showed phototransformation during laser irradiation due to ring reduction. The singlet oxygen quantum yields (Φ_Δ), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.51 to 0.94. Thus, these complexes show potential as photodynamic therapy of cancer.     

1,9-Bis(N,N-dimethylaminomethyl)dipyrromethanes in the synthesis of porphyrins bearing one or two meso substituents

A synthesis of 5,15-disubstituted zinc-porphyrins has been developed that employs condensation of a 1,9-bis(N,N-dimethylaminomethyl)dipyrromethane+a dipyrromethane in refluxing ethanol containing zinc acetate followed by oxidation with DDQ. The N,N-dimethylaminomethylation of the dipyrromethane was achieved via Eschenmoser's reagent (N,N-dimethylmethyleneammonium iodide) in CH₂Cl₂ at room temperature. The synthesis is compatible with diverse substituents (e.g., alkyl, aryl, ester, acetal) and enables rapid synthesis of trans-AB-, A₂-, and A-porphyrins. The synthesis of >40 zinc porphyrins has been surveyed; 13 zinc porphyrins were isolated in yields of 5-20% without detectable scrambling.     

Cytoplasmic delivery of quantum dots via microelectrophoresis technique

Nanoparticles with specific properties and functions have been developed for various biomedical research applications, such as in vivo and in vitro sensors, imaging agents and delivery vehicles of therapeutics. The development of an effective delivery method of nanoparticles into the intracellular environment is challenging and success in this endeavor would be beneficial to many biological studies. Here, the well-established microelectrophoresis technique was applied for the first time to deliver nanoparticles into living cells. An optimal protocol was explored to prepare semiconductive quantum dots suspensions having high monodispersity with average hydrodynamic diameter of 13.2–35.0 nm. Micropipettes were fabricated to have inner tip diameters of approximately 200 nm that are larger than quantum dots for ejection but less than 500 nm to minimize damage to the cell membrane. We demonstrated the successful delivery of quantum dots via small electrical currents (–0.2 nA) through micropipettes into the cytoplasm of living human embryonic kidney cells (roughly 20–30 μm in length) using microelectrophoresis technique. This method is promising as a simple and general strategy for delivering a variety of nanoparticles into the cellular environment.     

Tuning the emission property of carbazole-caped cyclometalated platinum(II) complexes and its application for enhanced luminescent oxygen sensing

Carbazole-caped cyclometalated platinum(II) complexes aryl-R-ppyPt(acac) (where ppy = 4-phenylpyridine, acac = acetylacetonato, aryl = carbazole and R is linker) were synthesized. The carbazole group is attached to the ppy ligand via α-diketo moiety (Pt-1) and (Pt-2) or C?C single bond (Pt-3), by Sonogashira or Negishi coupling reactions. We found that the ethynylene bonds of the C^N ligands were oxidized to α-diketo or methylene-keto structure during the metalation with K₂PtCl₄. Emissions beyond 550 nm were observed for Pt-1, with electron-withdrawing α-diketo moiety attached to ppy ligand, compared to the emission at 486 nm for the parent complex ppyPt(acac). Extended phosphorescence lifetime (τ_P = 12.4 μs) and enhanced phosphorescence quantum yield (Φ_P = 66%) were observed for Pt-3 compared to ppyPt(acac) (τ_P = 2.4 μs and Φ_P = 15%), we attribute the enhanced phosphorescence property to the electron-donating carbazole substituent. With density functional theoretical calculations (DFT), we found that the carbazole moiety is involved in the HOMO (Pt-3), the α-diketo moiety is involved in the LUMO (Pt-1), thus the energy gaps between the HOMO and LUMO in both cases were decreased and red-shifted emission is expected, compared to ppyPt(acac). The different emission properties of 1,2-dione containing complexes (Pt-1 and Pt-2) and the Pt-3 were rationalized by the spin density surface analysis of the complexes. The luminescent O₂ sensing properties of these complexes were studied in solution and in polymer films, for which fast response time (3.3 s) and recovery time (3.7 s) were observed. Two-site model fitting indicated that complex Pt-3 is the most sensitive O₂ sensing material among the complexes studied herein, with quenching constant of K_SV = 0.0238 Torr^?1.