Polymorphism of amino acid-based dendrons: From organogels to microcrystals

Article abstract of DOI:10.1002/asia.201000529

There is a delicate balance for a low-weight molecule to behave as a gelator or crystal. The synthesis of two novel amino acid-based naphthalene-dendrons, Nap-G1 and Nap-G2 is described. Both dendrons display polymorphic properties in organic solvents. Nap-G1 developed a fibrous network with β-sheet architecture in cyclohexane but exhibited a spherulitic network in mixed solvents (chloroform/petroleum ether 1:5, v/v). On the other hand, Nap-G2 acted as an efficient organogelator in chloroform but formed crystalline fibers in relatively high polarity solvents (such as acetone and methanol). Combinations of characterizations have been employed to study the polymorphism. In the balance: Two amino acid-based naphthalene-dendrons display different polymorphic properties in organic solvents. Nap-G1 developed a fibrous network with β-sheet architecture in cyclohexane but exhibited a spherulitic network in mixed solvents while Nap-G2 acts as an efficient organogelator in chloroform but formed crystalline fibers in relatively high polarity solvents (see picture).