The cyclooligomerization of arylethynes in ionic liquids catalysed by ruthenium porphyrins: a case of real catalyst recycling

An efficient cyclooligomerization of arylethynes, catalysed by ruthenium(II) porphyrins in environmentally friendly ionic liquids, with an effective recycling of the catalyst and easy isolation of the products is described

Imidazolium-based ionic liquids for the efficient treatment of iron gall inked papers.

Iron gall inks have been known since Roman times, were widely used in the Medieval Age, and became the most used ink in the Renaissance period. They were still officially used by the German Government as recently as 1973. The two main constituents of the ink are tannic acid and ferrous sulfate (vitriol). The vitriol normally used was not very pure and likely contained a mixture of iron sulfate with traces of other metals, in particular, copper. Certain transition-metal ions contained in iron gall inks and their acidity are known to deteriorate paper. Therefore, stabilization treatments consist of deacidification and the addition of antioxidants. To this end, the use of tetraalkylammonium bromides was recently proposed. Here, it is shown that 1-butyl-2,3-dimethylimidazolium bromide both in aqueous and in alcoholic solution can prevent the oxidative deterioration of cellulose. Furthermore, it does not lead to the yellowing of paper nor does it significantly affect the colour of the ink

New antioxidants for treatment of transition metal containing inks and pigments

Corrosive iron and copper ions and acids in iron gall inks and in certain pigments such as verdigris and malachite lead to enhanced degradation of paper. A recent EC co-funded project "InkCor" proposed the use of tetraalkylammonium bromides in combination with magnesium ethoxide in alcoholic solution for stabilizing these media. In the present paper, the potential stabilising effect of another type of antioxidants - alkylimidazolium bromides - is compared to the one achieved using either an aqueous calcium or magnesium phytate treatment or a non-aqueous solution of tetrabutylammonium bromide in combination with magnesium ethoxide in ethanol. Two new antioxidants, 1-ethyl-3-methylimidazolium bromide and 1-butyl-2,3-dimethyl-imidazolium bromide, in combination with alkali magnesium ethoxide in ethanol, effectively stabilised iron gall ink containing model paper. The effect of stabilisation was superior to the previously studied antioxidants, i.e. tetraalkylammonium bromides and the two phytates. No negative side effects on the colour of the ink were observed, which makes the two antioxidants appealing alternatives to the currently used aqueous calcium phytate treatment. The study was extended also to the model papers containing corrosive copper pigments verdigris and malachite. The most effective treatment solution in this case was composed of tetrabutylammonium bromide and magnesium ethoxide in alcoholic solution. Although no negative side effects on paper containing iron gall ink or copper pigments were observed, it is imperative that the effects of the treatment solutions are studies also on a number of historical samples, before they are used for stabilisation of historical artefacts. © 2008 K. G. Saur Verlag 2008

Smart materials and concepts for photovoltaics: Dye sensitized solar cells

Recently the issue of clean energy generation for powering an ever growing and developing civilization has come to the fore in international communities. A range of strategic actions have been identified in order to reach the renewable energy goals of 2020. The photovoltaic will play an important role with annual growth rate of the order of 30%. Particular emphasis has been given to organic solar cells and in particular to dye solar cells (DSC). These have the potential to greatly reduce materials and fabrication costs. In this chapter we will be giving a brief survey of dye solar cell science and technology: both the material aspects, highlighting the contribution to the photovoltaic process played by the electrolyte and counter electrode materials, and the engineering issues involved in creating a module of interconnected cells, using different architectures, on a common substrate. It is the possibility of using solution processed techniques with many of the active materials of the cell that contributes to make organic semiconductor and hybrid DSC technology so promising