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Gold–silver core–shell nanoparticles stabilized with a common sweetener, aspartame (AuNP@Ag@Asm), combine the antimicrobial properties of silver with the photoinduced plasmon-mediated photothermal effects of gold. The particles were tested with several bacterial strains, while biocompatibility was verified with human dermal fibroblasts.

The synthesis of CF3OC(O)OOCF3, CF3OC(O)OOC(O)OCF3, and CF3OC(O)OOOC(O)OCF3 is accomplished by the photolysis of a mixture of (CF3CO)2O, CO, and O2. Pure CF3OC(O)OOCF3 and CF3OC(O)OOC(O)OCF3 are isolated after thermal decomposition of CF3OC(O)OOOC(O)OCF3 and repeated trap-to-trap condensation. Additional spectroscopic data of known CF3OC(O)OOCF3 are obtained by recording NMR, IR, Raman, and UV spectra: At room temperature CF3OC(O)OOC(O)OCF3 is stable for days in the liquid or gaseous state. The melting point is -38 degrees C, and the boiling point is extrapolated to 73 degrees C from the vapor pressure curve log p = 8.657-1958/T (p/mbar, T/K). The new compound is characterized by molecular mass determination and by NMR, vibrational, and UV spectroscopy. The new trioxide CF3OC(O)OOOC(O)OCF3 cannot be separated from CF3-OC(O)OOC(O)OCF3 by distillation due to their similar boiling points. CF3OC(O)OOOC(O)OCF3 decomposes at room temperature within hours into a mixture of CF3OC(O)OOC(O)OCF3, CF3OC(O)OOCF3, CO2, and O2. Its characterization is discussed along with a possible mechanism for formation and decomposition reactions.

The trifluoromethoxy radical is prepared in high yields by vacuum flash pyrolysis of CF3OC(O)OOC(O)OCF3 or CF3OC(O)OOCF3 highly diluted in inert gases, and subsequently isolated in inert gas matrices by quenching the product mixture at low temperatures. In the IR spectrum, six fundamentals have been observed and C s symmetry is concluded for the matrix-isolated CF3O· radical by comparison with predicted band positions and band intensities from ab initio calculations. This finding is at variance with results from the analysis of the rotational resolved fluorescence excitation spectra and dispersed fluorescence spectra of gaseous CF3O· radicals, where C 3 v symmetry was found. Possible explanations for this discrepancy are given. The UV spectrum in the spectral region 28000−43000 cm-1 has been measured for the first time, and two different electronic transitions are observed. The structure of the low energy transition à 2A1 ← X̃ 2E is in agreement with that in previous laser induced fluorescence spectra. Four vibrational progressions are found in the spectral range between the band origin at 28517 cm-1 and up to 32400 cm-1. The spectroscopic results are compared with the gas phase and ab initio computed values and are discussed in detail.

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The UV absorption spectra of CF(3)CHO, C(2)F(5)CHO, C(3)F(7)CHO, C(4)F(9)CHO, CF(3)CH(2)CHO, and C(6)F(13)CH(2)CHO were recorded over the range 225-400 nm at 249-297 K. C(x)F(2)(x)(+1)CHO and C(x)F(2)(x)(+1)CH(2)CHO have broad absorption features centered at 300-310 and 290-300 nm, respectively. The strength of the absorption increases with the size of the C(x)F(2)(x)(+1) group. There was no discernible (<5%) effect of temperature on the UV spectra. Quantum yields for photolysis at 254 and 308 nm were measured. Quantum yields at 254 nm were 0.79 +/- 0.09 (CF(3)CHO), 0.81 +/- 0.09 (C(2)F(5)CHO), 0.63 +/- 0.09 (C(3)F(7)CHO), 0.60 +/- 0.09 (C(4)F(9)CHO), 0.74 +/- 0.08 (CF(3)CH(2)CHO), and 0.55 +/- 0.09 (C(6)F(13)CH(2)CHO). Quantum yields at 308 nm were 0.17 +/- 0.03 (CF(3)CHO), 0.08 +/- 0.02 (C(4)F(9)CHO), and 0.04 +/- 0.01 (CF(3)CH(2)CHO). The quantum yields decrease with increasing size of the C(x)F(2)(x)(+1) group and with increasing wavelength of the photolysis light. The photolysis quantum yield at 308 nm for CF(3)CHO measured here is a factor of at least 8 greater than that reported previously. Photolysis is probably the dominant atmospheric fate of C(x)F(2)(x)(+1)CHO (x = 1-4) and is an important fate of C(x)F(2)(x)(+1)CH(2)CHO (x = 1 and 6). These results have important ramifications concerning the yield of perfluorocarboxylic acids in the atmospheric oxidation of fluorotelomer alcohols.

The open-chain trioxide CF(3)OC(O)OOOC(O)OCF(3) is synthesised by a photochemical reaction of CF(3)C(O)OC(O)CF(3), CO and O(2) under a low-pressure mercury lamp at -40 degrees C. The isolated trioxide is a colourless solid at -40 degrees C and is characterised by IR, Raman, UV and NMR spectroscopy. The compound is thermally stable up to -30 degrees C and decomposes with a half-life of 1 min at room temperature. Between -15 and +14 degrees C the activation energy for the dissociation is 86.5 kJ mol(-1) (20.7 kcal mol(-1)). Quantum chemical calculations have been performed to support the vibrational assignment and to discuss the existence of rotamers.