title: Collision-induced dissociation of II-VI semiconductor nanocrystal precursors, Cd2+ and Zn2+ complexes with trioctylphosphine oxide, sulfide, and selenide.
abstract: The metal (M = Cd2+ and Zn2+) complexes with trioctylphosphine chalcogenide (TOPE, E = O, S, and Se) are prepared by electrospray ionization, and their relative stabilities and intramolecular reactions are studied by collision-induced dissociation (CID) with Xe under single collision conditions. These metal-TOPE complexes are considered as molecular precursors for the colloidal synthesis of II-VI compound semiconductor nanocrystals employing TOPO as a metal-coordinating solvent and TOPS or TOPSe as a chalcogen precursor. Of the various [M + nTOPE]2+ (n = 2-7) ions generated by ESI, the n = 2-4 complexes are characterized by CID as a function of collision energy. The collision energy at 50% dissociation (E50%) is determined from the cracking curve and the relative stabilities of the complexes are established. Between the two metal ions, the zinc-TOPE complexes are more stable than the cadmium-TOPE complexes when n = 2-3, whereas their stabilities are reversed when n = 4. Of the TOPE, TOPO binds most strongly to the metal ion, while TOPSe does most weakly. Upon CID, loss of TOPE occurs exclusively from the tetra-TOPE complexes, while extensive fragmentation of TOPE takes place from the di-TOPE complexes, showing the signature of the metal chacogenide formation. The nucleation of nanocrystals appears to begin with cracking of [M + 2TOPE]2+ (E = S and Se).
authors: Bio-Nanotechnology Center, Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong Namgu, Pohang, Kyungbuk 790-784, Korea.
authors: Won Ja
authors: WJ
authors: Min
authors: Sunghan
authors: S
authors: Jung
authors: Sung Jun
authors: SJ
authors: Lim
authors: Yongwook
authors: Y
authors: Kim
authors: Seung Koo
authors: SK
authors: Shin
mesh_terms: D002104:Cadmium / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry; D012643:Selenium / Q000737:chemistry*; D012666:Semiconductors; D021241:Spectrometry, Mass, Electrospray Ionization; D013455:Sulfur / Q000737:chemistry*; D014732:Vibration; D014978:Xenon / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D002104:Cadmium; D014978:Xenon; D013455:Sulfur; C044965:trioctyl phosphine oxide; D012643:Selenium; D015032:Zinc