title: Ion strength and pH sensitive phase transition of N-isobutyryl-L-(D)-cysteine monolayers on Au(111) surfaces.
abstract: Self-assembled monolayers (SAMs) of N-isobutyryl-L-(D)-cysteine (NIBC) on Au(111) surfaces were successfully prepared by immersing the Au(111) surfaces in the preheated pure NIBC aqueous solutions for a certain time and characterized by means of scanning tunneling microscopy. Close-packed lamellar structures with a rectangular (4 x radical3) lattice were found both in the SAMs of L-NIBC and D-NIBC. The pH value of the aqueous solutions was found to be sensitive to adjust the SAM structures during the assembly. Changing the pH value from 5 to 7 may completely shift the SAM structures from close-packed lamellar phase to loose-packed perpendicular phase. Combined with density functional theory calculations, such kind of phase transition was explained by the breaking of hydrogen bonds between carboxylic groups and the formation of extra interactions between COO(-) and Au.
authors.affiliation: Physicalisches Institut, Muenster University, D-48149 Muenster, Germany.
authors.forename: Haiming
authors.initials: H
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: Taolei
authors.initials: T
authors.lastname: Sun
authors.forename: Harald
authors.initials: H
authors.lastname: Fuchs
authors.forename: Lifeng
authors.initials: L
authors.lastname: Chi
mesh_terms: D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D015394:Molecular Structure; D009994:Osmolar Concentration; D010316:Particle Size; D044367:Phase Transition; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; C096972:N-isobutyrylcysteine; D006046:Gold; D003545:Cysteine