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Stable Pd(0) and Rh(0) nanoparticles with small and narrow size distribution can be prepared from relative large and agglomerated transition-metal particles dispersed in 1-n-butyl-3methylimidazolium hexafluorophosphate ionic liquid by simple laser irradiation. The laser irradiation is a complementary method for the generation of stable metal colloids in ionic liquids and also for the regeneration of small-size nanoparticles that may result from their agglomeration after different applications.

Uma série de líquidos iônicos 1-alquil éter (e 1-alquil)-3-metilimidazólio 2-4 ([C x O y MIm] + [Ânion] ou [C x MIm] + [Ânion] , onde MIm = 3-metilimidazólio; C x O y = 1-alquil éter, C 7 O 3 = -(CH 2 ) 2 O(CH 2 ) 2 O(CH 2 ) 2 OCH 3 (A), C 3 O 1 = -(CH 2 ) 2 OCH 3 (B); C x = 1-alquil, C 10 = C 10 H 21 (C), C 4 = C 4 H 9 (D); e [Ânion] = H 3 CSO 3 (2), BF 4 (3) ou PF 6 (4)) foram preparados e caracterizados. A força da ligação de hidrogênio entre o cátion e o ânion dos líquidos iônicos 2-4 depende principalmente do ânion e diminui na ordem H 3 CSO 3 > BF 4 > PF 6 . Todos os líquidos iônicos metanosulfonatos 2 possuem uma forte desblindagem para o próton H 2 do ciclo imidazólio. Os líquidos iônicos funcionalizados com um grupo 1-alquil éter mostram densidades mais altas em comparação com seus equivalentes do grupo 1-alquil. Os sais 2a-b, 3a-d e 4a-b são líquidos iônicos à temperatura ambiente. E, todos os líquidos iônicos 1-alquil éter funcionalizados (exceto 4b) são completamente amorfos. As maiores faixas líquidas foram obtidas com os líquidos iônicos tetrafluoroborato devido as suas solidificações a temperaturas baixas e excelente estabilidade térmica. Estes dados fornecem informações importantes para o entendimento sobre possíveis aplicações e a preparação de líquidos iônicos com tarefas específicas.A set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium ionic liquids 2-4 ([C x O y MIm] + [Anion] or [C x MIm] + [Anion] , where MIm = 3-methylimidazolium; C x O y = 1-alkyl ether, C 7 O 3 = -(CH 2 ) 2 O(CH 2 ) 2 O(CH 2 ) 2 OCH 3 (A), C 3 O 1 = -(CH 2 ) 2 OCH 3 (B); C x = 1-alkyl, C 10 = C 10 H 21 (C), C 4 = C 4 H 9 (D); and [Anion] = H 3 CSO 3 (2), BF 4 (3) or PF 6 (4)) was prepared and characterized. The cation-anion hydrogen bonding strength showed to be mainly anion dependent and decreased in the order H 3 CSO 3 > BF 4 > PF 6 . All methanesulfonate ionic liquids 2 possessed a strongly deshielded H 2 imidazolium ring proton. 1-Alkyl ether functionalized ionic liquids showed higher densities in comparison to their 1-alkyl equivalents. The salts 2a-b, 3a-d and 4a-b are room-temperature ionic liquids. All 1-alkyl ether functionalized ionic liquids (except 4b) are completely amorphous. The widest liquid ranges were obtained with the tetrafluoroborate ionic liquids due to their late solidification and excellent thermal stability. These data provide important information for the understanding of their application scope and the preparation of task-specific ionic liquids.Keywords: imidazolium ionic liquids, ether-functionalized, hydrogen bonding, physicochemical properties, task-specific IntroductionRoom-temperature ionic liquids (RTILs), ionic salts that melt at and below ambient temperature, typically comprise of an organic cation and an organic or inorganic anion. The class of imidazolium RTILs is used in a wide variety of applications due to their attractive physical and chemical properties, 1-3 which include: air and moisture stability, low flammability, thermal stability, a neglectable vapor pressure, bei...

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Hydrogen reduction of cationic or neutral Ir(i) compounds, namely [Ir(COD)(2)]BF(4) and [Ir(COD)Cl](2)respectively. in the ionic liquid (IL) 1-alkyl-3-methylimidazolium tetrafluoroborate affords either irregularly sized spherical (from 1.9 +/- 0.4 to 3.6 +/- 0.9 nm) or worm-like metal nanoparticles, depending on the nature of the imidazolium alkyl group and the type of iridium precursor. The ionic Ir(i) precursor tends to be dissolved and concentrated on the IL polar domains (populated by the imidazolium nucleus and tetrafluoroborate anions) while the neutral precursor dissolves preferentially in the non-polar region of the IL (populated mainly by N-alkyl side chains). The size, or volume, of the nano-region where the Ir(i) precursor is dissolved and reduced, determines the size and, probably, the shape of the formed nanoparticles. The HR-TEM image shows that the Ir(0) with worm-like shape are polycrystalline and formed from aggregation individual "spherical" nanoparticles of around 1.9 nm. The catalytic activity of Ir(0) NPs on the hydrogenation of cyclohexene (0.01 mol L(-1) of Ir atoms in IL, 75 degrees C, 8 bar of H(2), 500 rpm stirring, 1/1000 Ir(0)/cyclohexene ratio) is always greater in C(1)C(10)I.BF(4) than C(1)C(4)I.BF(4), regardless of the nature of Ir(i) precursor. Moreover, the cyclohexene hydrogenations performed with Ir(0) nanocatalysts made from ionic Ir(i) precursor are approximately twice faster than those NPs obtained from the neutral Ir(i) precursor, in the same IL.