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β‐Alanine‐Based Dendritic β‐Peptides: Dendrimers Possessing Unusually Strong Binding Ability Towards Protic Solvents and Their Self‐Assembly into Nanoscale Aggregates through Hydrogen‐Bond Interactions
Author(s) -
K.K. Mong Tony,
Niu Aizhen,
Chow HakFun,
Wu Chi,
Li Liang,
Chen Rui
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010202)7:3<686::aid-chem686>3.0.co;2-z
Subject(s) - dendrimer , hydrogen bond , chemistry , amide , branching (polymer chemistry) , alanine , intermolecular force , solvent , molecule , peptide , polymer chemistry , self assembly , stereochemistry , organic chemistry , amino acid , biochemistry
A series of poly(β‐alanine) dendrimers 1 – 4 with Boc‐carbamate as the surface functionality, β‐alanine as the dendritic branch, 3,5‐diaminobenzoic acid as the branching agent, and 1,2‐diaminoethane as the interior core has been synthesized by a solution‐phase peptide‐coupling method. The structural identities and purities of the products have been fully characterized by spectroscopic and chromatographic methods. 1 H NMR studies on the dendrimers indicated that the Boc‐carbamate surface groups exist as a mixture of syn and anti rotamers in solution, and that the dendrimers adopt an open structure in polar solvents; this allows the free interaction of the interior core functionality with solvent molecules. Due to the cooperative effect of a large number of carbamate and amide groups, the dendrimers exhibit an unusually strong binding ability towards protic solvents and behave as H‐bond sponges. As a result, the H/D exchange rates of the N−H protons are significantly enhanced in such dendritic structures, as compared to those of nondendritic carbamates and amides. These dendritic peptide dendrimers also exhibit a strong tendency to form nanoscopic aggregates in nonpolar or polar aprotic solvents through intermolecular H‐bond interactions.