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/Co-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.