Self-assembled layers based on isomerizable stilbene and diketoarylhydrazone moieties.
The ability to form self-assembled layers on gold (Au) using five organosulfur compounds that contain isomerizable groups has been investigated. The isomerizable groups are either stilbene or diketoarylhydrazone derivatives. To anchor them on a gold surface, the isomerizable groups have been combined with sulfur-containing groups (disulfide, 1,2-dithiolane, and thiophene). The resulting thin films assembled on gold were characterized by X-ray photoelectron spectroscopy (XPS), infrared (FTIR) reflectance spectroscopy, ellipsometry, and water contact angle measurements. Though all substances have the potential to form self-assembled monolayers (SAMs), only two of them, disulfanediyl-bis(ethane-2,1-diyl) bis(4-styrylbenzoate) (1) and 4-[(2,4-dioxo-3-pentylidene)diazane-2,2,1-triyl]phenyl thioctate (4), yield the expected structure, the latter one showing the possibility to incorporate diarylketohydrazone moieties into SAMs. The compound 4-[(2,4-dioxo-3-pentylidene)diazane-2,2,1-triyl]phenyl thiophene-2-carboxylate (5) does not self-assemble on gold, but 4-styrylphenyl thioctate (3) presumably forms multilayers. In the case of disulfanediyl-bis(ethane-2,1-diyl) bis[4-(p-nitrostyryl)benzoate] (2), we propose a structure with a fraction of the molecules bound to gold via the nitro group. The results show that the propensity of organosulfur compounds to self-assemble on gold not only is determined by the sulfur-containing group but also is affected by the complete molecule.
Marten
Jan
J
Technische Universität Bergakademie Freiberg, Institut für Organische Chemie, Leipziger Strasse 29, 09596 Freiberg, Germany.
Erbe
Andreas
A
Critchley
Kevin
K
Bramble
Jonathan P
JP
Weber
Edwin
E
Evans
Stephen D
SD
D006046:Gold / Q000737:chemistry*; D006834:Hydrazines / Q000138:chemical synthesis / Q000737:chemistry*; D007536:Isomerism; D008567:Membranes, Artificial; D008958:Models, Molecular; D015394:Molecular Structure; D013267:Stilbenes / Q000138:chemical synthesis / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
D006834:Hydrazines; D008567:Membranes, Artificial; D013267:Stilbenes; D013438:Sulfhydryl Compounds; D006046:Gold