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Fluorescence and Raman spectra of two representative bridged [14]annulenes, namely 1,6:8,13-ethanediylidene[14]-annulene and 1,6:8,13-propanediylidene[14]annulene are measured. The Raman spectra are measured using several excitation wavelengths in pre- and/or near-resonance conditions with respect to the L(sub a) and B(sub a) states.

Vibrational spectra of bridged [14]annulenes with an anthracene perimeter are presented and discussed on the basis of density functional calculations with the B3LYP functional and 6-31G** and cc-pVDZ, basis sets. The Raman spectra are obtained exciting at 647.1 and 1064 nm, that is, in pre- and off-resonance excitation conditions, respectively.

Research has been conducted on the five-coordinate iron(III) complexes. The results of the (super)1 H NMR analysis of this complex demonstrate the downfield shifts for pyrrole resonances.

Synthesis of homogeneous hepta-antennated C-6 branched sialosyl cyclomaltoheptose derivatives were performed in good yields and the compounds were fully characterized. The preparation of such multivalent sialosidea with potential biorecognizable properties contributes to expand the existing array of such glycoforms.

The chemoenzymatic synthesis of the racemate and the one enantiomer of the fluorinated analogue of the natural cyclooxygenase inhibitor lasiodiplodin is described. The formation of the 12-membered lactone by a ring-closing metathesis is the key step in this synthesis.

A synthesis of the C(29)-C(45) bis-pyran subunit of spongistatin 1 is described. The C(29)-c(45) bis-pyran subunit can be assembled through an aldol reaction between a suitably functionalized F-ring methly ketone and 2,3-syn aldehyde.

P-nitrosophosphates represent new asymmetric N-O heterodienophiles that react with 1,3-dienes to produce complex oxygen-, nitrogen-, and phosphorous- containing cycloadducts and permit the direct introduction of the phosphoramidate functional group. P-nitrosophosphates also reacts with water to yield nitoxyl, the biologically important one-electron-reduced form of nitric oxide.

Reaction conditions are developed for the conjugate addition of alpha-nitrogen heteroatom functionalized cuprate reagents with the less reactive carboxylic acid derivatives. The conjugate addition reactions of alpha-aminoalkylcuprates to alpha,beta-unsaturated carboxylic acid derivatives proceeds eventually when used with CuCN.2LiCl.

The synthesis, characterization and dynamic nature of gem-dimethyl-functionalized cyclooctapyrrole and cyclododecapyrrole are presented. Formation of the larger cyclododecapyrrole is a result of the gem-dimethyl effect.

A study was conducted to analyze the tautomeric exchange of the inner hydrogens of free base alkylporphycenes using 13CCPMAS and 15N-CPMAS nuclear magnetic resonance (NMR) at different temperatures. The Bruker MSL-300 was utilized to determine the CPMAS NMR spectra. Results indicated the possibility of detecting rotations in the alkyn chains by determining variations in the relaxation times as a function of temperature.

Fine-line electronic absorption and fluorescence spectra of porphycene and 2,7,12,17-tetra-n-propylporphycene were obtained in low-temperature nitrogen, argon, krypton and xenon matrices. A well-resolved emission spectrum of porphycene was also measured in an isotropic glassy matrix by employing the fluorescence line-narrowing method. Vibronic and site structure in the region of S0-S1 and S0-2 electronic transitions of porphycenes were assessed against that of porphyrins. No site structure was seen in the spectra of porphycenes in xenon and krypton matrices.

Cobalt(III) and cobalt(II) derivatives are the compounds most often characterized in metallocorrole synthesis. The electrochemical and spectroscopic properties of neutral and oxidized (OEC)M, with OEC the trianion of 2,3,7,8,12,13,17,18-octaethylcorrole, have been examined. The oxidation of (OEC)Co, (OEC)Ni and (OEC)Cu proceeds as a formation of dimeric species, contrasting with (OEC)Mn, which occurs only as a monomer in both neutral and oxidized forms.

The synthesis and electrochemical examination of two Sn(IV) corroles, represented as (OEC)Sn(C(sub6)H(sub5)) and (OEC)SnC1, was undertaken. Three reversible one-electron oxidations were observed, each occurring at the conjugated macrocycle. Two electrons are involved in the reduction of (OEC)SnC1, and (OEC)-Sn(C(sub6)H(sub5)) is reversibly reduced by a single electron giving an Sn(IV) corrole varPi-anion radical.

Syn and anti bismethanol[14]annulenes were used to test the accuracy of the semiempirical (PM3) and ab initio (HF and MP2), as well as density functional theory methods (BLYP and B3LYP). Compared to experimental data, PM3 and HF overemphasized bond localized structures, while the correlated MP2 and density functional methods favored overly delocalized aromatic structures. B3LYP computations gave the best agreement with the available experimental data.

Single-electron and multielectron reductions of 2,3,6,7,11,12,17,18-octaethylcorrphycene (H2OECn) and its Sn(IV), Fe(III), Co(II), Ni(II), Cu(II) and Ag(II) compounds in 2-propanol solutions were investigated by radiolytic methods. Formation and decay of unstable intermediates formed upon one-electron reduction were examined by kinetic spectrophotometric pulse radiolysis. The absorption spectra of stable reduction products were also recorded after gamma-radiolysis.

A study was conducted to characterize the geometry, tautomerism, isomerism and stability of porphyrin isomers. Twenty seven structures based on E/Z-configurations and NH tautomerism were analyzed in the study. Computations were carried out using a Pople Gaussian 92 DFT program. Results indicated a rapid interconversion between two anti tautomers. Findings also suggested that the rate of exchange was sensitive to both temperature and isotopic substitutions.

Two high-valent phenyl sigma-bonded cobalt corroles in +IV and +V oxidation states are synthesized and analyzed by electrochemistry, spectroscopy and structural characterization. The compounds are represented as (OEC)Co(C6H5) and ((OEC)Co(C6H5))ClO4, in which OEC is the trianion of 2,3,7,8,12,13,17,18-octaethylcorrole. The former is a novel example of the only isolated tetrapyrrole complex that has a strong cobalt(IV) property. It exhibits three reversible one-electron transfers in PhCN containing 0.2 M TBAP.

The electrochemical and spectroscopic characteristics of three iron corroles were examined. Benzonitrile, dichloromethane and pyridine containing 0.1M tetra-n-butylammoniun perchlorate or tetra-n-ethylammonium hexafluorophosphate were used as supporting electrolyte. An iron(IV) tetrapyrrole pi cation radical has been isolated and characterized as a perchlorate. The strong antiferromagnetic coupling between the iron(IV) center and the singly oxidized corrole macrocycle has been confirmed by Mossbauer, X-ray crystallographic and magnetic susceptibility studies.

Synthetic procedures enable the preparation of (OEC)Fe(III)(NO), the first neutral iron(III) nitrosyl tetrapyrrole, with OEC being the trianion of 2,3,7,8,12,13,17,18-octaethylcorrole. The complex undergoes up to three oxidations, and the first two reversible oxidations occur stepwise at the corrole macrocycle producing a stable iron(III)pi-cation radical and dication. Both oxidation products have a coordinated NO axial ligand, and cyclic voltammetric studies reveal the occurrence of two one-electron reductions of the complex.

Cyclic voltammetric studies help examine the redox properties of sigma-bonded metalloporphycenes, (EtioPc)M(C6H5) where M=Fe or In and EtioPc = dianion of 2,7,12,17-tetraethyl-3,6,13, 16-tetramethylporphycene in different mediums. (EtiOPc)Fe(C6H5) undergoes three one-electron oxidations generating an iron(IV) porphycene, an iron(IV)Pi cation radical and a dication respectively. Both sigma-bonded systems exhibit two one-electron reductions at the conjugated Pi ring system. Spectrochemical data and a comparative study with (EtiOPc)FeCl/and (EtioPC)In(C6H5) help assign electron transfer centers for oxidation and reduction of (EtioPc)Fe(C6H5).

Dynamic liquid-state 1H NMR and solid-state 15N cross polarization magic angle spinning NMR spectroscopies help determine rate constants and kinetic HH/HD/DD isotope effects, associated with the intramolecular double-proton transfer of 15N-labeled porphyrin in liquid and polycrystalline states. These parameters are same for both states and liquid state degeneracy of tautomerism is conserved in the solid-state. Arrhenius diagram shows that the stepwise tautomerism involves a metastable intermediate having a thermally activated tunneling of low temperature.

An analysis of Fe(III) mu-oxo porphycene dimers reveals that they are stable under nine different cyclic voltammetric time scale-based oxidation states. Thin-cell layer-based reduction yields two stable reduced ((Pc)Fe)2O forms. Spectral data reveal that the dimer reduction occurs at the conjugated pi-ring system.

ENDOR and TRIPLE-resonance spectroscopy are used to explore the extremely resolved spectra of two paramagnetic species, 3.+ and 3.- during the generation of radical cation (3.+), radical anion (3.-) and (3(super 2-)) of tetraoxaporphycene from the neutral compound (3) and the dication (3(super 2+)). Absorption spectra of five redox phases in the UV/visible/near-IR site and emission bands of three diamagnetic species resemble those of isomeric and isoelectronic tetraoxaporphyrins, 4(super 2+)-4(super 2-).

A molecular orbital study on the five redox stages of tetraoxaporphyrin using UV/visible/near-infrared and electron paramagnetic resonance spectroscopies was presented. The five redox stages which included the dication, the neutral molecule, the radical cation, the radical anion and the dianion featured varying electronic structures and molecular configurations. Moreover, structural properties that influenced the behavior of the molecular orbitals were identified.

A study is made on the photophysical and photochemical properties of new tetrapyrrolic macrocycle 8 and its lower 22pi homologs 6 and 7. These properties are compared to those of 18pi porphycene 5. The results indicate the absence of phosphorescence in any of compounds 6-8, thereby, necessitating other means of triplet energy determination. The results also exhibit favorable comparison with the corresponding performance of the parent porphycene 5.

The synthesis of N,N'-Polymethylene-syn-1,6:8,13-diimino(14)annulenes showed that the radical cations must be regarded as N-centered radicals in which two atoms support the majority of the spin population. ESR, ENDOR and TRIPLE resonance spectroscopy were used to examine the radical cations of the series and their derivatives.