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Hydrogel Formation Using New L ‐Lysine‐Based Low‐Molecular‐Weight Compounds with Positively Charged Pendant Chains
Author(s) -
Suzuki Masahiro,
Yumoto Mariko,
Kimura Mutsumi,
Shirai Hirofusa,
Hanabusa Kenji
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390179
Subject(s) - chemistry , bromide , polymer chemistry , nanofiber , fluorescence , amide , pyridinium , sulfonic acid , lysine , side chain , hydrophobic effect , organic chemistry , polymer , chemical engineering , amino acid , biochemistry , physics , quantum mechanics , engineering
Low‐molecular‐weight compounds based on L ‐lysine with alkylpyridinium or ‐imidazolium groups have been synthesized and studied for their gelation behavior in H 2 O. Most compounds formed gels below a concentration of 2.5 weight‐%, the pyridinium bromide 2a and the 1‐methyl‐1 H ‐imidazolium bromide 3 even at 0.1 weight‐%. The minimum gel concentration (MGC) necessary for hydrogelation increased with increasing length of the Lys N α ‐alkanoyl chain, but the gelation ability concomitantly decreased. Electron‐microscopic images demonstrated that these hydrogelators create a three‐dimensional network in H 2 O by entanglement of self‐assembled nanofibers. A fluorescence study with 8‐anilinonaphthalene‐1‐sulfonic acid (ANS) proved that some hydrophobic aggregates are formed at hydrogelator concentrations below an MGC of less than 50 μ M (0.004%). FT‐IR, 1 H‐NMR, and Fluorescence studies indicated that the driving forces for the self‐assembly into nanofibers are mainly hydrophobic interactions and H‐bonding between amide groups.