Cation supramolecular

However, the DLVO model cannot completely explain the stabiUzation properties of imidazoUum ILs towards the lr(0) nanoparticles as it treats counterions as mono-ionic point charges and was not designed to account for sterically stabiUzed systems. Together with the electrostatic stabilization provided by the intrinsic high charge of the IL, a steric type of stabilization can also be envisaged. This is due to the presence of anionic and cationic supramolecular aggregates of the type [(BMl),t(X),( ] [(BMl),t (X)J"T where BMl is the l- -butyl-3-methyUmidazoUum cation and X is the anion. 

This entry to supramolecular chemistry allows one, at the same time, to develop a host-guest chemistry because the space inside the cucurbituril barrel is sufficient to confine small "guesf molecules. This is illustrated with the crystallization of the supramolecular adduct [W3S4(H20)8Cl](pyH ccuc) Cl4a 5.5 H2O with a pyridinium cation inside the cucurbituril cavity [48]. The introduction of guest molecules may vary the net charge on the assembly and consequently the whole packing in the solid state. 

A supramolecular assembly of macromolecules bearing antenna dendron has been reported. Pyrazole-anchored PBE dendrons were synthesized to examine the coordination behavior to transition-metal cations (Cu, Au, Ag) [31]. Self-assembled metallacycles were found. The Cu-metallacycle further formed luminescent fibers about 1 pm in diameter. The luminescence (605 nm) occurred by the excitation of the dendron (280 nm) and the excitation spectrum was coincident with the absorption spectrum of the dendron, suggesting the antenna effect. Interestingly, the luminescence of the Cu-metallacycle fiber disappeared when the fiber was dissociated into the individual metallacycles in C2H2. 

One of the most successful approaches to the synthesis of metalla-supramolecular systems has been by templated self-assembly processes. Most of the templating agents used by synthetic chemists are either cationic or neutral species. Anions, on the other hand, have only fairly recently been successfully utilized as templates. The new metalla-macrocycles [Pd2Ni2(atu)4(PPh3)4X]3+ (atu = deprotonated amidinothiourea, X = C1, Br, I) have been prepared using anion templated syntheses. Only in the presence of each of these three halides are the metalla-macrocycles... 

Another important class of pigment are the so-called toner pigments. These are water-soluble dyes containing sulfonic acid groups which are insolubilized by forming a salt with a divalent cation such as calcium and barium5 (Scheme 2). Until recently the toner pigments were perceived merely as insoluble salts but X-ray studies have shown them to exist as supramolecular metal complexes (see Section 9.12.4.2). 

In 2005, Matsuda and co-workers [20] synthesized a MnniPc complex salt, TPP[MnmPc(CN)2] DCM (93) with huge [MnmPc(CN)2] anions and large TPP+ cations. There are two crystallographically independent [MnmPc(CN)2]- molecular units. The central Mnm ions of each unit lie at the inversion centre. The two unique MninPci CN)2 units form ID supramolecular anionic chains via weak type J and... 

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