Bolaamphiphile
Bolaamphiphiles (also known as “Bolatenside” or “Bolas” for short) are a special type of amphiphilic molecule. They have at least two hydrophilic head groups that are separated by a sufficiently long, hydrophobic part of the molecule. The name " Bola " has its origin in the similarity of the molecular shape to a throwing weapon of indigenous peoples and was introduced in 1951 by Raymond M. Fouss and David Edelson.
structure
The molecules are divided into hydrophilic and hydrophobic areas according to their affiliation with the surfactants . The main hydrophilic units are carboxyl , ammonium , polyethoxy groups and sugar monomers, while the hydrophobic part of the molecule is formed from alkyl and phenyl groups . The synthetic Bolas, which are obtained through condensation and coupling reactions, are of particular importance.
properties
Compared to surfactants with a single head group, bolate surfactants have a higher water solubility, a higher critical micelle concentration (CMC) and a lower mean aggregation number. In aqueous solution, micelles and vesicles can form in various forms , depending on the concentration . Bolaamphiphiles, which are in a relatively rigid conformation due to a linkage via phenyl nuclei, can produce fiber-like micelles that are characterized by a high degree of helicity . In addition, the formation of stable, transparent gels in aqueous solution can be observed.
Occurrence and uses
The cell membrane of extremely thermophilic archaea contains the amphiphilic caldarchaeol, which runs through the entire membrane. All other living things have double membranes.
It is possible to simulate the monolayer membranes of the archae "bacteria" with Bolas. After a hydrophilic group has been covalently attached to a solid substrate, they are used as a coating material for electrodes . Through the further chemical derivatization of the remaining functional group , Bolas are used in processes based on molecular recognition.
literature
Jürgen-Hinrich Fuhrhop, Tianyu Wang: Bolaamphiphiles . In: Chem Rev. . tape 104 , no. 6 , 2004, p. 2901-2937 .
Jürgen-Hinrich Fuhrhop, Detlev Fritsch: Bolaamphiphiles Form Ultrathin, Porous, and Unsymmetric Monolayer Lipid Membranes . In: Acc. Chem. Res . tape 19 , 1986, pp. 130-137 .
R. Nagarajan: Self-assembly of Bola amphiphiles . In: Chem. Eng. Commun . tape 55 , no. 1-6 , 1987, pp. 251-273 .
Individual evidence
- ↑ RM Fouss, D. Edelson, J. Am. Chem. Soc. , 73, 1951 , 269-273.