Crystal and liquid crystalline polymorphism in 1-alkyl-3-methylimidazolium tetrachloropalladate(ii) salts

Hardacre, Christopher; Holbrey, John D.; McCormac, Paul B.; McMath, S.E.J.; Nieuwenhuyzen, Mark; Seddon, Kenneth R.

doi:10.1039/b008091h

Cited by 83 publications

(87 citation statements)

References 28 publications

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“…Although other techniques such as infrared spectroscopy, X-ray, and neutron diffraction studies have been used to study these ions in the liquid or solid state or at surfaces [6,52,[109][110][111][112][113][114][115][116][117][118][119][120], a real gain in our understanding came with the combination of crystal structure solution, Raman spectroscopy and ab-initio DFT calculations [108,121]. We concentrate the story on the instructive example of the l-butyl-3-methylimidazolium cation, [C 4 mim] þ (see Fig.…”

Section: Brief Introduction To Ab-initio Model Calculationsmentioning

confidence: 99%

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

2007

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Summary.A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C 4 mim][X]) salts. The rotational isomerism of the [C 4 mim] þ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the ''localized structure features'' that apparently exist in ionic liquids are described. It is hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed.

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Section: Brief Introduction To Ab-initio Model Calculationsmentioning

confidence: 99%

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

2007

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“…2,3 Moreover, the pyridinium and imidazolium cations of ILs can coordinate to MX 4 2-(M = Co, Ni, Cu, Zn, Cd, Pd and X = Cl, Br) complex ions and form ionic liquid crystals (ILCs). [4][5][6][7][8][9][10][11] Because these ILCs contain a metal center and have a high degree of order, they are prime candidates for the synthesis of inorganic nanostructures. As the first example, our group has recently fabricated a macroporous network of CuCl platelets from a Cu-containing ILC.…”

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Photoreduction of a crystalline Au(III) complex: A solidstate approach to metallic nanostructures

et al. 2006

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Inorganic particles, especially gold particles, 1 are probably one of the most intensely researched fields in chemistry today. Classical procedures for inorganic particle synthesis include vapor phase reactions and wet chemistry in water and organic solvents. Recently, also ionic liquids (ILs) have been used to fabricate well-defined inorganic particles. 2,3 Moreover, the pyridinium and imidazolium cations of ILs can coordinate to MX 4 2-(M = Co, Ni, Cu, Zn, Cd, Pd and X = Cl, Br) complex ions and form ionic liquid crystals (ILCs). [4][5][6][7][8][9][10][11] Because these ILCs contain a metal center and have a high degree of order, they are prime candidates for the synthesis of inorganic nanostructures. As the first example, our group has recently fabricated a macroporous network of CuCl platelets from a Cu-containing ILC. As these ILCs serve as precursors for inorganic matter, we have termed them ionic liquid crystal precursors, ILCPs. 12, 13 Unlike conventional precursor/solvent/ reactant mixtures, ILCPs are "all-in-one" reactant-solventtemplates. 3,12,13 Other research groups have recently adapted this concept and presented their own ILCPs. [14][15][16] The current paper shows that not only mesophases (i.e. ILCs) but also crystalline ILC analogs can template inorganic particles. Specifically, we show that dodecylpyridinium tetrachloroaurate is a precursor for the formation of gold platelets with a nanometer thickness and a micrometer width. The fabrication of inorganic particles from a crystalline metal complex precursor is a new concept that could be useful for many other inorganic materials, especially metallic nanostructures. Indeed, Chen et al. have recently shown that the controlled thermolysis of a silver thiolate yields uniform silver nanodisks. 17 ExperimentalMetal complex synthesis Dodecylpyridinium chloride (Fluka) was recrystallized three times from THF (Aldrich) yielding a white powder. 284.5 mg of dodecylpyridinium chloride and 398 mg of NaAuCl 4 (Aldrich) were dissolved in 15 mL of water and vigorously stirred at room temperature (Scheme 1). A bright yellow precipitate appeared immediately and the suspension was stirred in the dark for another 30 min. to complete the reaction. The precipitate was filtered, washed with cold water, and dried under vacuum for 12 hours. The resulting complex 1 is soluble in THF, dioxane, and acetonitrile, but insoluble in water, chloroform, and toluene. 1 H-NMR (400 MHz, DMSO-d6, TMS) δ 0.84 (t, 3H), 1.24 (broad, 18 H, J), 1.90 (m, 2H), 4.61 (m, 2H), 8.15 (m, 2H), 8.58 (m, 1H), 9.15 (d, 2H). 13 C NMR (400 MHz, TMS) 146.4, 145.7, 128.9, 67.9, 61.5, 41.0, 40.8, 40.6, 40.4, 39.8, 32.2, 31.7, 29.9, 29.8, 29.7, 29.6

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“…If an anion has a long alkyl chain, the long alkyl chains on the imidazolium ring are not necessary for the formation of LC . In addition, some metal complex anion, such as PdCl 4 − and CuCl 4 − , can be applied (Bowlas et al, 1996;Hardacre et al, 2001;Lee et al, 2004;Lin & Vasam, 2005). Generally, the temperature range for LCs can be adjusted by altering counter anion and the length of alkyl chain.…”

Section: Thermotropic Liquid Crystal Phase Of Ionic Liquidsmentioning

confidence: 99%