Studies of Cluster-Assembled Materials: From Gas Phase to Condensed Phase

Open Access
Author:
Gao, Lin
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 10, 2008
Committee Members:
  • Albert Welford Castleman Jr., Committee Chair
  • Thomas E Mallouk, Committee Member
  • Ayusman Sen, Committee Member
  • Elizabeth C Dickey, Committee Member
Keywords:
  • Zr6
  • Met-Cars
  • Assemble
  • Materials
  • Clusters
  • Au-MPC
Abstract:
The discovery of Met-Cars has drawn worldwide interests and has been actively investigated. However, the unsuccessful search for a solvent capable of isolating Met-Cars has impeded progress in characterizing the material in the condensed state and, hence, limited its potential applications as a novel nanoscale material. An alternative method involving the deposition of mass-gated species and the subsequent structural investigation via Transmission Electron Microscopy (TEM) has been employed. With particularly interesting results, soft-landed deposits of zirconium Met-Cars were found to form a face-centered-cubic (FCC) structure with a lattice parameter ~ 15Å. Experimental results of reactions run with a solvothermal synthesis method are reported. One unexpected product in single crystal form was isolated and tentatively identified by X-ray diffraction to be [Zr6iO(OH)12O6]•2[N(Bu)4], with space group P21/n and lattice parameters of a =12.44 Å, b=22.06 Å, c =18.40 Å, α = 90, β = 105,  = 90, V = 4875 Å 3 and R1=3.15 % for the total observed data (I ≥2 σI) and R2 = 2.82 %. This work could suggest a direction in which the preparation of Zr-C cluster-assembled materials in a liquid environment may be eventually fulfilled. 1,3-Bis(diethylphosphino)propane (depp) protected small gold clusters are studied via multiple techniques, including Electrospray Ionization Mass Spectrometry (ESI-MS), Ultraviolet-Visible Spectroscopy (Uv-Vis), Nuclear Magnetic Resonance (NMR) for solution phase and Transmission Electron Microscopy (TEM) for the condensed phase. In particular, undeca-, dodeca- and trideca-gold clusters protected by depp and halogen ligands, i.e.[Au11-13(depp)4Cl2-4]+, are found to be all predominant and persist in solution for months, while they gradually and spontaneously grow into a monomial tridecagold clusters series. Such spontaneous-growth behavior and the resultant SAAs observations are correlated by icosahedra-close-packing modes of clusters, following “magic numbers” rules. ~7 shells of such cluster packing are proposed to be in the SAAs.