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Novel, eco-friendly, and halogen-free polyphosphazene-based flame retardant (FR) cathodes for Li-S batteries are prepared by the inverse vulcanization of elemental sulfur with polybis(2-acrylamidoethoxy)phosphazene (poly(AAE)) resulting in the covalently bonded different wt% sulfur content polymers. Due to the polar amide groups, poly(AAE)-xS (x refer to the wt% of sulfur) composites assist in anchoring intermediate lithium polysulfide species. The structural characterizations of the poly(AAE)-xS polymers are conducted by elemental analysis, Fourier-transform infrared spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and scanning electron microscopy. Their FR properties are elevated by calculation of the limiting oxygen index values and burning tests. Later, lithium-ion storage mechanism of poly(AAE)-55S polymer is evaluated, including cyclic voltammetry, rate performance tests and electrochemical impedance spectroscopy measurements. To compare with the electrochemical performance of poly(AAE)-55S, a noncovalent blend polymer mixture and bare sulfur are also tested. It is found that covalently bonded poly(AAE)-55S obtained by the inverse vulcanization of elemental sulfur and poly(AAE) results much pronounced capacities. Herein, new insights into the design and development of alternative cathode materials for safer Li-S batteries, both providing FR properties and good lithium polysulfides adsorption capabilities, are offered.

A series of different Na content P2- and O3-type Na-x(Fe0.35Mn0.35Co0.3)O-2 (x = 0.5, 0.6, 0.7, 0.8, 0.9) were successfully synthesized by sol-gel method. The newly prepared materials were examined by means of X-ray diffraction. They were characterized by scanning electron microscopy (SEM-EDS) and inductively coupled plasma mass spectrometry (ICP-OES). The electrochemical performances of these materials were studied to understand the effect of the Na content. The initial discharge capacities of P2-type Na-0.5(Fe0.35Mn0.35Co0.3)O-2 is 122.5 mAh g(-1), Na-0.6(Fe0.35Mn0.35Co0.3)O-2 is 114.7 mAh g(-1), and Na-0.7(Fe0.35Mn0.35Co0.3)O-2 is 136.5 mAh g(-1) at 0.05 C. After 110 cycles of these materials, the discharge capacities dropped to 55.6 mAh g(-1), 71.2 mAh g(-1), and 89.0 mAh g(-1) at 0.05 C, respectively. The initial discharge capacities of O3-type Na-0.8(Fe0.35Mn0.35Co0.3)O-2 and Na-0.9(Fe0.35Mn0.35Co0.3)O-2 are 145.6 mAh g(-1) and 120.2 mAh g(-1) at 0.05 C, respectively. After 110 cycles of these materials, the discharge capacities dropped to 94.2 mAh g(-1) and 24.95 mAh g(-1) at 0.05 C, respectively. Given these results, P2-type Na-x(Fe0.35Mn0.35Co0.3)O-2 (x = 0.5, 0.6, and 0.7) have higher cycling stability than the O3-type Na-x(Fe0.35Mn0.35Co0.3)O-2 (x = 0.8 and 0.9).

Two new, three component multimodular cis-tris-BODIPY-cyclotriphosphazene-cis-tris-fullerene systems (7 and 11) were designed and synthesized. In these derivatives, the triad bearing unsubstituted three-cis-BODIPY units (7) exhibited insolubility due to the appendment of three fullerenes on one molecule whereas the attachment of long alkyl chains enabled the solubility of the triad, distryl-BODIPY-cyclotriphosphazene-fullerene (11). The photophysical properties of the distryl-BODIPY-cyclotriphosphazene-fullerene (11) were investigated by means of absorption and fluorescence spectroscopies. As a result of extended conjugation, the distryl-BODIPY-cyclo-triphosphazene-fullerene triad (11) revealed absorbance and emission in the near-IR range in solution. The results are compared to those of the parent molecule, distryl-BODIPY-cyclotriphosphazene dyad system (10). Photoexcitation of the distryl-BODIPY-cyclotriphosphazene-fullerene triad (11) in solution results in quenching of emission. The fluorescence lifetime of triad 11 in solution is on the order of picoseconds. The triad (11) was also used as heavy-atom-free triplet photosensitizer for photooxidation of 1,3-diphenylisobenzofuran via the photosensitizing of singlet oxygen (O-1(2)) in three different solvents, dichloromethane, chloroform and acetonitrile. This multi-fragment donor-acceptor system demonstrated singlet oxygen production in all selected solvents.

Novel heavy atom free triad type triplet photosensitizers composed of unsubstituted and distyryl BF2-chelated dipyrromethene (BODIPY), cyclotriphosphazene and fullerene- C-60, were newly synthesized using multistep synthetic procedure. Rigid cyclotriphosphazene core enabled fated non-geminal-cis-tris arrangement of chromophores (BODIPY) and fullerene- C60 as spin converter. All newly synthesized compounds were characterized by MALDI-MS, H-1, C-13 and P-31 NMR. Optical absorption and emission studies were systematically performed in solution by comparing with the reference compounds to establish the photophysical properties of the triads. The new heavy atom free triplet photosensitizers contain three light harvesting antennas as well as combined with different absorption wavelengths resulting in high molar extinction coefficients. Singlet oxygen generation capacities of novel triads are measured using the trap molecule 1,3-diphenylisobenzofuran. Also, both triads demonstrate chemical and photo stability under the environment of singlet oxygen measurement.

Novel zinc(II) phthalocyanines bearing boron dipyrromethene (BODIPY) (8) and its mono-styryl (9) and di-styryl (10) derivatives containing p-(N,N-diethylamino)benzaldehyde moieties were designed and synthesized for the first time. These phthalocyanines (8-10) were prepared by the copper-free Sonogashira coupling reaction of terminal ethynyl functionalized BODIPYs [4,4'-difluoro-8-(4-propynyloxy)-phenyl-1,3,5,7-tetramethy1-4-bora-3a,4a-diaza-s-indacene (2), 4,4'-difluoro-8-(4-propynyloxy)-pheny1-3,5,7-trimethyl-1-((4-diethylaminophenyl)ethenyl)-4-bora-3a,4a-diaza-s-indacene (5), or 4, 4'-difluoro-8-(4-propynyloxy)-pheny1-3,5-dimethyl-1,7-bis((4-4 ''-diethylaminophenyl)ethenyl)-4-bora-3a,4a-diaza-s-indacene (6)] with tetrakis(iodo) zinc(II) phthalocyanine (7). All newly synthesized compounds were fully characterized by elemental analysis and general spectroscopic methods such as H-1 NMR, FT-IR, mass, UV-Vis, and fluorescence. The photophysical (fluorescence quantum yields and lifetimes), photochemical (singlet oxygen generation capability and photodegradation behaviors) properties of these phthalocyanines were also investigated for determination of their photodynamic therapy (PDT). The results obtained indicated that these conjugates could be promising photosensitizers for PDT applications. (C) 2016 Elsevier Ltd. All rights reserved.