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The surface-supported corannulene (COR)-[C.sub.60] host-guest complexes are formed by deposition of [C.sub.60] onto a COR lattice on Cu(110). The studies have shown that the bistability has originated from a subtle interplay between homo- and heteromolecular interactions.

An experimental plan is developed for measuring the effective hydrogen/deuterium steric kinetic effect (KIE), which is based on greater bowl depth and barrier to bowl inversion in sym-1,3,5,7,9-pentamanisyl-corannule when compared to corannulene. The results have shown the usefulness of the N-heterocyclic carbene (NHC) ligand even for the coupling reaction with multichlorides.

An efficient method is described to prepare symmetric 7,8,9,10-substituted fluoranthenes from the reaction of peri-diynes and alkynes catalyzed by Wilkinson's complex. The crystal structure of indenocorannulenes have helped in understanding the bowl-shaped geometry of these compounds and this new synthetic method has occurred under neutral conditions.

Quantum mechanical designs for planar delocalized cyclooctatetraene are discussed.

Research into structure/energy correlation of bowl depth and inversion barrier in corannulene derivatives is presented. The energy profile of an individual corannulene derivative was found to fit a mixed quartic/quadratic function.

A study on pi-sigma-pi through-bond coupling was conducted to determine if bond coupling can significantly increase C-C bond lengths. Ab initio calculations, such as restricted Hartree-Fock techniques, were used to predict molecular geometries and orbital energy trends. Structural analysis reduced the significance of classical pi-sigma-pi conjugation conflicts focused on bond lengthening. However, significant effects of stabilizing filled/empty pi-sigma-pi were evident during bond cleavage.

The postulate that bicyclic annelations are generally effective at inducing bond localization in the aromatic compound annulene is tested using fyran adducts of dimethyldihydropyrene. Results show a large down-field shift in the internal methyl signals when one adduct is compared with another, indicating bond localization in the former. Moreover, ab initio computations not showing dynamic electron correlation is found to be inadequate in modeling annulene's molecular structure.

The bond length of C2h in 1,2-diphenylethane is 1.54 angstroms, as obtained from high-level split valence ab initio calculations. Using the novel electronic interactions, an anomalously short Csp3-Csp3 (central) bond for 1,2-diphenylethane and a few derivatives is reflected more likely showing experimental displacement of parameters than an actual anomaly because this violates the conception of average molecular geometry.

Several derivatives of endo-1-Cr were synthesized, and the dynamic stereochemistry of endo-(starphenylene) chromium tricarbonyl, endo-1-Cr, was analyzed through NMR spectroscopic techniques. Ab initio calculations and NMR experimental findings prove the existence of impaired rotation around the metal-arene bond and intramolecular metal-arene migration chemistry. The first molecules to show smooth metal-arene exchange and comparatively impaired tripod rotation are the derivatives of endo-(starphenylene) chromium tricarbonyl (endo-1-Cr)t-10.

The study of triannelated benzene structures using semiempirical AM1 method and split valence 6-31G(D) at the restricted Hartree-Fock suggests that the Mills-Nixon postulate, predicted for the annealed benzenes, is not valid. This conclusion is reached after the analysis of ring strain and cyclic pi effects. A novel pattern in bond-alternating benzenes is suggested.

A new NMR study on fully-substituted aromatic hydrocarbons and their tricarbonylchromium complexes reveals a stereodynamic behavior largely unaffected by metal complexation. The steric effect is supported by Gutowsky- Holm calculations on the sp(super 2) to sp(super 3) rotational energybarriers and is attributed to the trisymmetry of the metal complex. This lock-and-key fit between metal tripod and the arene induces sterestabilization and inhibits possible rotation. A related rotation dynamics between the metal tripod and the ethyl group is discussed.

A ground-state [C.sub.2] trigonal-bipyramidal geometry adopted by 2,6-Bis(2,6-difluorophenyl)phenyldimethylsilanium ion in which fluorines from opposing 2,6-difluorophenyl groups coordinate to the apical positions of the pentavalent silyl cation is reported. The exchange of fluorine at silicon occurs via a disrotatory gearing mechanism wherein one fluorine remains coordinated to silicon throughout the circuit.

A synthetic pathway was designed for the formation of corannulene, an aromatic hydrocarbon with a C5v symmetry, by using a path which retain the bilateral symmetry of the precursors. The compound 3, 6-dimethylacenapthen-1- one obtained from 1,6,7,10-tetramethylfluoroanthene was treated with bromine in the presence of NBS and carbon tetrachloride to give a tetrabromo compound which yielded corannulene by direct flash thermolysis. Displacement, oxidation and pyrolysis reactions gave corannulene and its dihydro and tetrahydro derivatives which were structurally characterized.

The crystal of angular-(terphenylene)chromium tricarbonyl (1-Cr) takes on an octahedral conformation, with the three short arene bonds comprising one face and the three carbonyls comprising the opposite. MMX and local density functional (LDF)calculations as well as NMR analysis agree reasonably with the X-ray structuralanalysis, particularly in bond alternation and differential bond lengthening. They also explain well the unusually high barrier to rotation about the metal-arene bond revealed by conformational analysis.

The concepts of close packing in monolayers of 5-fold-symmetric buckybowls are described. The results have shown that the chiral 5-fold-substituted chloro and methyl derivatives have not shown the tilt and have maintained the 5-fold symmetry as adsorbates.

The syntheses, crystal structures, ab initio density functional theory calculations and photophysical properties of 1,6-di-, 1,2,5,6-tetra-, and 1,3,5,7,9-pentaethynyl-substituted coraanulenes are described. Most of the aryl derivatives have exhibited high-quantum-efficiency solution luminescence and variable emission wavelengths that are dependent on the nature of the substitution.

The synthesis and structure of monodispersed single-walled carbon nanotubes (SWCNT) from per-ethynylcorannulenes are described using a solution-phase method. Cognates [C.sub.40[H.sub.10] are the first members in the series of 5-fold symmetric SWCNT and potential seed compounds for preparing monodisperse higher order SWCNT.

The syntheses of two new cognates, dodecamethoxy-tricyclobutabenzene (TCBB) and hexaoxo-TCBB, through 3-fold [2+2] cycloadditions of benzyne and ketene silyl acetals (KSAs) are reported. The structures and properties of these compounds are characterized computationally.

The structure and energetics of a series of two-atom-bridge annelated cyclooctatetraenes is determined by ab initio and hybrid density functional quantum mechanical computations. Results indicated that the overall electron count and the essential components of the Clar/Robinson rule work well to predict the exo/endo preferences.

Research was conducted to examine the facile transformation of halo-to alkylcorannulenes using trimethylaluminum and catalytic nickel salts. Structural computations of corannulene, sum-Pentamethylcoraulene and decamethylcorannulene were carried out at the restricted Hartree-Fock level of theory using the analytically determined gradients and search algorithms within GAMESS and hybrid density functional methods using GUASSIAN98. Results prove that halo and alkyl substitution as well as palladium-mediated ring closure represent methods that are useful and complementary to previously developed low valent titanium ring closing methods.

A study was conducted to obtain structural computations on a series of annelated oligoperilenes called [n]canastanes at the restricted Hartree-Fock level of theory using the analytically determined gradients and search algorithms within GAMESS. Additional hybrid density functional methods were obtained using GAUSSIAN94 to uncover effects of dynamic correlation. The canastane motif should furnish an important challenge to synthetic and computational methods. Experimental methods and results are discussed.

An alternative design strategy was created for the synthesis of bifunctional photorefractive polymers with net gain derived from simple siloxane polymers and platinum catalyzed hydrosilation chemistry. The photorefractive properties of these materials were examined through a two-beam coupling experiment. Photorefraction was seen for each of the bifunctional polymers. Results showed that the strategy is useful for rapid and variable synthesis of bicomponent polymeric materials and may be applied to the rational design of structure-function assays.

The experimental C(sp3)-C(sp3) bond length in 1,1,2,2-tetraphenyl-3,8-dichloronaphtheno-cyclobutane was confirmed by reexamining its X-ray crystal structure. A suitable level of theory and model structure was constructed to measure the bond length computationally. The classical steric argument without the need for orbital interactions such as through-bond coupling influenced the reliability of the compound's bond length.

The reaction of corannulene with (C5Me5)Ru-(NCMe)3+O3SCF3- was marked as the first transition metal complex of corannulene and as the first example of n6-coordination to a curved polynuclear aromatic hydrocarbon surface. A slight extension of Ru-to-arene centroid distance in the complexes of 7-exo coordinated Ruthenium as compared to simple benzene analogues. Furthermore, the cyclopentadienyl and arene rings remain essentially parallel.

The synthesis of the first corannulene-based cyclophane has been accomplished. It involves the condensation of a diketone with 4-hetanone to obtain a cyclopentenone carbinol which is reacted with 2,5-norbornadiene in acetic anhydride to yield 1,6-dimethyl-7,10-diethylfluoranthene. The compound, for which three conformational isomers are feasible, was characterized using nuclear magnetic resonance and high-resolution mass spectroscopies as well as ab initio calculations. It showed no coalescence or peak broadening when heated to 148 degrees Celsius.

2-chlorobicyclo(2.1.1)hex-2-ene undergoes Wittig elimination to produce a highly strained bicycloannelated benzene, trisbicyclo(2.1.1)hexabenzene (A). Mass spectrometry helps determine the molecular weight of A. Ab initio studies demonstrate the existence of significant strain in bicyclo(2.1.1)hexyne. NMR spectroscopy helps characterize A.

Analysis of a series of 2,6-bis(p-X-phenyl)benzoic acids reveals the influence of polar-pi interactions on the properties of carboxylic acid functional groups. Polar-pi effects are transmitted through space along with strong field and pi-polarization components. These space effects should be considered when designing molecular receptors and catalysts and in their mode of action.

1H NMR spectroscopy is utilized in the investigation of the chirotopicity of the methyl group in (alpha-deuterio-o-chlorotoluene)chromium tricarbonyl. The hydrogens of a chirotopic methylene group are located in diastereotopic environments and chirotopicity is usually exhibited as an AB pattern in the 1H NMR spectrum of the molecule. The tricarbonyl compound is prepared from the reduction of alpha-bromo-o-chlorotoluene with lithium aluminum deuteride in tetrahydrofuran, followed by treatment with chromium hexacarbonyl in refluxing diglyme.

A study synthesized corannulene and different alkyl derivatives of corannulene using solution-phase chemistry highlighted by organometallic C-C coupling methods. Substitution of the rim of corannulene expands the scope of this class of compounds. Alkyl substitution can especially influence bowl depth, crystal packing, HOMO-LUMO gap and inversion dynamics. Alkyl corannulenes can be used as building blocks for larger structures such as cyclophanes, dendrimers and liquid crystals.