Chiral II-VI semiconductor nanostructure superlattices based on an amino acid ligand.
Reaction of L-cysteine with M(NO3)2 x xH2O (M = Cd, Zn) generates M(L-cysteinate), which feature one-dimensional substructures that can be viewed as fragments of bulk structures of CdS (rock salt high pressure phase) and ZnS (wurtzite) because of the bridging modes accessible to the sulfur atom of L-cysteine. The MS substructures are arranged in a regular and periodic fashion within the crystal via the carboxylate function of L-cysteine. Considering the structural similarities with bulk materials, the optical properties of M(L-cysteinate) were studied and indicate blue shifts of the band gap of 2.59 eV (M = Cd, compared to CdS rock salt) and 1.37 eV (M = Zn, compared to ZnS wurtzite) with respect to the bulk MS structures, due to the low dimensionality of the metal-sulfur arrangement. The chelating nature of the cysteine ligand imposes an unusual mer arrangement of three binding S moieties at Cd with a correspondingly high Cd coordination number in a chalcogenide-based material. Density of states calculations show strong electronic structure similarities with the bulk phases and rationalize the band gap changes.
Rebilly
Jean-Noël
JN
Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
Gardner
Paul W
PW
Darling
George R
GR
Bacsa
John
J
Rosseinsky
Matthew J
MJ
D000596:Amino Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D049329:Nanostructures / Q000737:chemistry*; D011789:Quantum Theory; D012666:Semiconductors; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013455:Sulfur / Q000737:chemistry
D000596:Amino Acids; D008024:Ligands; D013455:Sulfur