1.  Monte Carlo simulated annealing strategies, carried out on four different potential energy surfaces, were applied to benzene-cyclohexane clusters, BC_n, n = 3-7, 12 to identify low-energy isomers and to trace the evolution of structures as a function of cluster size.  Initial structures were first heated to ensure randomization and subsequent annealing yields optimized rigid, low-energy clusters.  Five major structural isomers are identified for BC₃:  one assumes the form of a symmetric, modified sandwich; the remaining four lack general symmetry, assuming distorted tetrahedral arrangements.  For BC₄ and larger clusters, the number of low-temperature isomers is large.  It is, nevertheless, feasible to classify isomers into Groups based on structural similarities.  The evolution of BC_n structures as a function of cluster size is observed to follow one of two primary paths:  the first maximizes benzene-cyclohexane interactions and places benzene in or near the BC_n cluster center; the competing path maximizes cyclohexane-cyclohexane interactions and distances benzene from the cluster's center of mass.  Results for BC₃ and BC₄, analyzed with reference to experimental results and models previously applied to interpret benzene-argon cluster spectra, suggest that the additivity model will need to be modified and extended to account for nonpolar solutes that are neither compact nor spherical.

            2.  Neat fluorobenzene, (H₆H₅F)_n, and mixed fluorobenzene-benzene, (C₆H₆)_m(C₆H₅F)_n, clusters were examined via resonant two-photon ionization (R2PI) spectroscopy through fluorobenzene's B₂ ← A₁ 0⁰₀ transition.  The fluorobenzene molecule's R2PI spectrum was analyzed  with reference to an MP2/6-31+(2d,p) ground state frequency calculation.  The ultraviolet cluster spectra contain no unique sharp features, indicating the presence of many isomers for all cluster sizes.  Ongoing analysis focuses on determining the cluster size evolution of three broader features ubiquitous through the spectra.  These features may hold the key to assigning structural types and the evolution of their relative populations as a function of size.

            3.  Carbon, hydrogen, and 2D NMR spectra were obtained for the 1,2,3 – alternate dibenzyl bis-teo (alt) and the cone – dibenzyl bis-teo (cone) calixarene structures.  Although many of the NMR peaks had been previously assigned, some such assignments remained ambiguous.  Theoretical NMR shifts and Mulliken charges were calculated via Gaussian 03W software.  Optimized structures, charge distributions, and ground state energies were calculated using the B3LYP/6-31G(d) method/basis set.  Proton and carbon NMR spectra were calculated based on optimized structures, using the HF/6-31G(d) method/basis set.  Calculations were carried out for both isomers, first in the gas phase—with and without imposed symmetry, and  then in solution with a chloroform solvent.  Results indicate that imposed symmetry leads to higher optimized energies:  thus, the molecules prefer forms slightly distorted from high symmetry structures.  In contrast, imposed symmetry does not noticeably affect predicted NMR shifts:  shifts of non-symmetrized forms—averaged over positional-equivalent atoms—do not differ systematically from corresponding shifts calculated for fully symmetrized forms.  Analysis is underway to correlate Mulliken charges to steric compression, as observed in the NMR data.