MALDI TOF mass spectrometry for the characterization of phosphorus-containing dendrimers. Scope and limitations.

Neutral phosphorus-containing dendrimers with aldehyde groups at the periphery have been analyzed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) up to generation four. Although the expected quasi-molecular ion is generally observed, the mass spectral pattern, presence of fragments and adducts related to the original skeleton, is highly relevant to the sample preparation (nature of the matrix: 2-5-dihydroxybenzoic acid (2.5-DHB), 1,8-dihydroxy-9[10H]-anthracenone (dithranol), 6-azathiothymine, 2,4,6-trihydroxyacetophenon, 7-hydroxycoumarin or 2-anthramine, and addition of alkali metal salts).

Naked Au55 clusters: dramatic effect of a thiol-terminated dendrimer.

Reaction of the thiol-terminated fourth-generation dendrimer 2-G4 (96 SH groups) with the gold cluster compound Au55(PPh3)12Cl6 in a 3:1 molar ratio in dichloromethane results in the formation of bare Au55 clusters. The cuboctahedrally shaped Au55 particles coalesce to well-formed microcrystals (Au55) infinity. The role of the dendrimer is not only to remove the phosphine and chlorine ligands but also to act as an ideal matrix for perfect crystal growth.

Versatile Complexation Ability of Very Large Phosphino-Terminated Dendrimers.

The synthesis of phosphino-terminated dendrimers is described up to the tenth generation, which possess more than 3000 phosphino groups (3-[G'(10)()]). Several complexation reactions of these dendrimers toward various low oxidation states transition metal derivatives have been carried out, up to generation 5 for iron (4-[G'(5)()]: 96 Ph(2)P-->Fe(CO)(4) groups), generation 4 for tungsten (5-[G'(4)()]: 48 Ph(2)P-->W(CO)(5) groups), generation 10 for gold (6-[G'(10)()]: 3072 Ph(2)P-->Au-Cl groups), and generation 6 for rhodium (8-[G'(6)()]: 192 Ph(2)P-->Rh(acac)(CO) groups). These reactions demonstrate that the phosphino-terminated dendrimers behave analogously to monophosphines, in spite of the nanometer size of the high generations.

Phosphorus-Containing Dendrimers. Easy Access to New Multi-Difunctionalized Macromolecules.

Phosphorus-containing dendrimers 1-[G'(1)]-1-[G'(4)] (generation 1 to generation 4) possessing terminal aldehyde groups reacted with a variety of hydrazino compounds. Addition of hydrazine itself to 1-[G'(1)]-1-[G'(4)] afforded the corresponding dendrimers 2-[G(1)]-2-[G(4)] with hydrazono groups at the periphery. Addition of methylhydrazine to 1-[G'(1)], 1-[G'(4)] gave the dendrimers 3-[G(1)], 3-[G(4)].