Chiral, Polyionic Dendrimers with Complementary Charges − Synthesis and Chiroptical Properties

Abstract

Chiral dendrimers up to the second generation have been prepared from enantiopure aromatic bis‐ and tris(amino acids) by peptide coupling techniques. The dendrimers could be deprotected to yield water‐soluble polyamine and/or polycarboxylic acid macromolecules. Two complementary types, with respect to the charges carried in water at pH = 7, were synthesised. A chiroptical study of the protected dendrimers, which were soluble in THF and CHCl3, was conducted. The results of that study indicate that the solution shapes of these dendrimers are rather decongested, with little steric interaction between different parts of the dendritic structure.

Eu(III) complexation of phenyltrisalanine and phenylbisalanine in aqueous solution studied by photoluminescence and UV spectroscopy

“…Recrystallisation from EtOAc/heptane provided the product as a white powder (0.79 g, 39% This compound (0.42 g, 0.87 mmol) and LiOH (1.6 g, 67 mmol) were treated as above to yield the free acid as colourless oil (0.45 g, 99%). 2 Residual water was very difficult to remove even after prolonged evacuation at 0. The free acid (0.50 g, 0.96 mmol) was hydrogenated using Pd/C (50 mg) as described in the literature [5] to give 2 as a white powder (0.24 g, 99%).…”

“…The conventional Job plot ½C vs. ½H 0 =ð½H 0 þ ½G 0 Þ; where ½G 0 is the concentration of the metal ion, was then determined. The saturated compound (0.20 g, 0.30 mmol) was hydrolysed using LiOH (1.6 g, 67 mmol) as described previously [2] and produced the free carboxylic acid as a white amorphous powder (0.18 g, 95%). 1 This compound (100 mg, 156 mmol) was deprotected using TFA as described previously [5] to give the title product as a white powder (49 mg, 99%).…”

“…As part of our ongoing project in synthesising potential molecular receptors, dendrimers [1,2] and cage compounds [3], we earlier prepared derivatives, which, by simple deprotection, afforded phenyltrisalanine (Pta) 1 and its bisarmed analogue 2 (phenylbisalanine, Pba) [4,5] (Scheme 1).…”

“…2-3% per stereocentre, was previously estimated which we assume also in this case 2. This same degree of epimerisation was estimated to occur in this case as described above.R.D.…”

Convenient Synthesis of Benzene‐1,3,5‐tricarbaldehyde and Congeners

“…[1,2] We have used them as starting materials for the synthesis of phenyl 1,3-bis-and 1,3,5-tris-alanine derivatives as well as some dendrimers and ferrocene analogs. [3,4] Selective reactions of one of several identical functional groups in the same molecule are always plagued by more or less statistical distributions of products. Easily available starting materials carrying differentiated latent functional groups would therefore be interesting candidates for the synthesis of more advanced sectorial compounds.…”