title: Temperature-dependent structural change of D-penicillamine-capped chiral gold nanoparticles investigated by infrared spectroscopy.
abstract: The structure and stability of D-penicillamine-capped gold nanoparticles (d-Pen Au NPs) were studied using spectroscopic tools. The synthesis of d-Pen Au NPs was examined using high-resolution transmission electron microscopy (HR-TEM), UV-vis absorption spectroscopy, and circular dichroism (CD). Temperature-dependent reversible structural changes of d-Pen Au NPs were observed using infrared spectroscopic tools. The three thiol, carboxyl, and amino binding groups of d-Pen were presumed to interact with Au NP surfaces on the basis of the infrared spectral features. d-Pen appeared to form quite a stable structure and desorb at a high temperature above 453 K on Au NPs. Our deconvolution analysis indicated the ν(s)(COO(-)) and ν(as)(COO(-)) carboxylate bands at ∼1,392 and ∼1,560 cm(-1) appeared to be weakened, whereas the amino band at ∼1,595 cm(-1) remained strong in increasing the temperature from 293 to 373 K. On the other hand, the intensities of the zwitter ionic bands at ∼999, ∼1,117, and ∼1,631 cm(-1) for NH(3)(+) appeared to decrease presumably due to the deprotonation process at 373 K. Our infrared spectroscopic study suggests that the deprotonated amino groups bind stronger, whereas the intra-carboxylate bonds become weaker as the temperature increase. Such structural changes of d-Pen Au NPs appeared to be reversible between 293 and 373 K.
authors.affiliation: Department of Chemistry, Soongsil University, Seoul 156-743, Republic of Korea.
authors.forename: Kwang-Su
authors.initials: KS
authors.lastname: Ock
authors.forename: Uuriintuya
authors.initials: U
authors.lastname: Dembereldorj
authors.forename: Jin
authors.initials: J
authors.lastname: Park
authors.forename: Erdene-Ochir
authors.initials: EO
authors.lastname: Ganbold
authors.forename: Semi
authors.initials: S
authors.lastname: Kim
authors.forename: Hang-Cheol
authors.initials: HC
authors.lastname: Shin
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Joo
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010396:Penicillamine / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013696:Temperature
chemical_list: D002614:Chelating Agents; D006046:Gold; D010396:Penicillamine