SYNTHESIS AND PROPERTIES OF MONODISPERSE CHIRAL DENDRIMERS (UP TO 4THGENERATION) WITH DOUBLY BRANCHED BUILDING-BLOCKS - AN INTRIGUING SOLVENT EFFECT

'Fully chiral' dendrimers, containing a stereogenic center at each and every branching point, have been prepared using a chiral core triol w ith aromatic elongating units (cf. 27) and chiral branch diols (cf. 8, 12, and 24) as building blocks. The biggest dendrimer prepared is of the 4th generation (33:46 building blocks, 93 stereogenic centers, 10( 28) possible stereoisomers), and has been obtained by a convergent gro wth approach in 32 steps starting from the biopolymer poly[(R)-3-hydro xyburanoic acid] (P(3-HB)). Ail compounds were shown to be monodispers e by MALDI-TOF mass spectrometry. Spin-lattice relaxation-time (T-1) m easurements and size-exclusion chromatography show typical features of structurally related achiral dendrimers. The influence of the chiral building blocks on the share of the whole dendrimer has been investiga ted by chiroptical measurements: the specific rotation can be consider ed as average of all chiroptical properties of its constituent chiral units, independent of the solvent. the concentration, and the temperat ure. On the other hand, regularity in the circular dichroism (CD) spec tra is completely lost with variation of the solvent (cf. Fig. 13).