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The photochemistry of naphthols 1, 2, 4, 5 and 9, and phenol 10 has been studied in aqueous solution with the primary aim of exploring the viability of such compounds for naphthoquinone and quinone methide photogeneration, along the lines already demonstrated by our group for phenol derivatives. 1-Naphthol (1) is known to be substantially more acidic than 2-naphthol (2) in the singlet excited state (p[K.sub.a]* = 0.4 and 2.8, respectively) and it was expected that this difference in excited-state acidity might be manifested in higher reactivity of 1-naphthol derivatives for photochemical reactions requiring excited-state naphtholate ions, such as quinone methide formation. Our results show that three types of naphthoquinone methides (26a, 26b, and 27) are readily photogenerated in aqueous solution by irradiation of 1-naphthols. Photolysis of the parent 1-naphthol (1) in neutral aqueous solution gave 1,5-naphthoquinone methide 26a as well as the non-Kekule 1,8-naphthoquinone methide 26b, both via the process of excited-state (formal) intramolecular proton transfer (ESIPT), based on the observation of deuterium exchange at the 5-and 8-positions, respectively, on photolysis in [D.sub.2]O-C[H.sub.3]CN. A transient assignable to the 1,5-naphthoquinone methide 26a was observed in laser flash photolysis experiments. The isomeric 2-naphthol (2) was unreactive under similar conditions. The more conjugated 1,5-naphthoquinone methide 27 was formed efficiently via photodehydroxylation of 4; isomeric 5 was unreactive. The efficient photosolvolytic reaction observed for 4 opens the way to design related naphthol systems for application as photoreleasable protecting groups by virtue of the long-wavelength absorption of the naphthalene chromophore. Key words: photosolvolysis, excited-state intramolecular proton transfer, quinone methide, photorelease, photoprotonation.

N-Benzoyl- and N-arylsulfonyl-p-benzoquinone-mono-imine ketals (QIKs) undergo smooth Diels-Alder cycloadditions with typical 1,3-butadienes to yield the expected endo adducts. Treatment with catalytic acid rapidly converts the adducts to dihydronaphthalenes. The N-benzoyl derivatives require high pressures for cycloadditions while the N-tosyl and N-nosyl derivatives proceed under thermal (ambient pressure) conditions. In all cases the cycloadditions are completely regioselective. Key words: Diels-Alder, quinone imine ketal, hyperbaric chemistry.

Research describes the isolation and characterization of two quinones with unique terpenoid skeleton, pycnanthuquinones A and B from Pycnanthus angolensis plant. Data suggest that the quinones possess antihyperglycemic activity.

Results show that oxidation of beta-dicarbonyl compounds with manganese-(III)acetate results in the formation of radical, which further undergoes an addition to the C--C double bond of 1,4-naphthoquinone derivatives. Data indicate that the procedure is useful in the synthesis of acridine- and indole dionesfrom 2-amino-1,4-naphthoquinones and beta-dicarbonyl compounds.

Research has been conducted on the rhodium(III) 5,6-chrysenequinone diimine complexes. The design of these complexes is described.

Research has been conducted on the rubromycin group and their analogues. Results indicate the presence of a competitive interaction with respect to the telomerase substrate primer in the cause of inhibition by beta-rubromycin.

Research has been conducted on the oxygen consumption during 2,4,5-trihydroxyphenylalanine quinone (TPQ) biogenesis. Results indicate that oxygen consumption rate depends on the dissolved oxygen concentration.

The construction of the dendrimers containing electroactive sites requires replacing the five- carbon alkyl spacer unit in the extended building block, 1

The compound 4,6-dimethyl-o-quinone methide (4) was generated by flash vacuum pyrolysis of alcohol 3 or of the trimer 6 and matrix isolated in Ar at 7.6 K. Photolysis of 4 with long wavelength light at the said temperature produced 4,6-dimethylbenzoxete (5). The compound 5 can be transformed back to 4 by UV irradiation at 254/190 nm. Quantum chemical computations on the thermal interconversion of 4 and 5 revealed activation barriers of the order of 40 kcal/mol for 4 -> 5, and 30 kcal/mol for 5 -> 4.

Chlorinated 4,4[prime]-diphenoquinones, previously unknown byproducts of thermal processes in the presence of chlorine, have been discovered in a variety of samples such as oil products from a waste pyrolysis plant, a fly ash from a municipal waste incinerator, and a sample of Kieselrot slag. The pyrolysis plant products also contained tetramethylated and unsubstituted 4,4[prime]-diphenoquinone. All compounds may be generated by oxidative coupling of phenols at elevated temperatures-a reaction that is considered to compete with the formation of the structurally isomeric dioxins. Once built-up, 4,4[prime]-diphenoquinones form a redox pair with the corresponding 4,4[prime]-dihydroxybiphenyis, with variable equilibrium positions depending on the prevailing conditions. For analysis, a cleanup method which involves liquid/liquid partition and solid-phase extraction was developed. The method is suitable for the determination of all substances of this class. Quantitative analysis was carried out by HPLC using an electrochemical detector for the fly ash and slag samples. Pyrolysis oil samples were quantitatively analyzed by GC/MS after derivatization with trifluoroacetic acid anhydride. Substance identification in all samples was performed by GC/MS. The samples were found to be contaminated with chlorinated diphenoquinones in the lower and middle ppb range. Pyrolysis oil products yielded up to 1 ppm methylated diphenoquinones. The amount of diphenoquinones in the samples is compared with their yield of chlorinated dioxins and furans as well as polychlorinated biphenyls (PCBs). Kieselrot especially was contaminated, with 25 ppm of polychlorinated dibenzo-p-dioxins/-furans (PCDD/F) and 94 ppm of hexachlorobenzene, while the pyrolysis oil samples contained up to 360 ppb of PCDD/F and up to 25 ppm of PCB.

A study was conducted to describe the magnetic and optical characteristics of chromium(III)-quinone complexes with regard to their electronic structures. The effect of electron exchange in these complexes was analyzed. Results revealed that a strong antiferromagnetic exchange interaction between the metal chromium(II) and the semiquinone ligand existed which can be attributed to the significant optical properties of the metal complexes.

The presence of quinones acting as electron acceptors in Chlorobium vibrioforme membranes and reaction center was analyzed using liquid chromatography. Anaerobic isolation of the membranes and the reaction center indicated two molecules per P840 of menaquinone-7, wherein more are bound to the membranes than to the reaction center. However, chlorobiumquinone was also found in the membranes. Electron paramagnetic resonance spectroscopy was used to determine the role of the quinone in electron transfer. The findings suggest that menaquinone-7 corresponds to phylloquinone in photosystem I.

The in situ measurement of EPR spectra of radical ions generated at the polarized liquid/liquid interface is described in relation to the 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrachloro-p-benzoquinone (TCBQ), and 2,3,5,6-tetrafluoro-p-benzoquinone (TFBQ) radical anions and the tetrathiafulvalene (TTF) radical cation. TCNQ and TTF were chosen as model compounds with which to quantify the performance of a novel liquid/liquid electrochemical EPR cell. The anion radical of TCNQ and the cation radical of TTF in 1,2-dichloroethane (DCE) were produced at the water interface by electron transfer from/to the aqueous-phase ferricyanide/ferrocyanide redox couple by applying a potential difference between the two phases with a four-electrode potentiostat. The EPR signal intensity (at constant magnetic field) of the resultant organic radicals was monitored during potential step experiments which indicated that the EPR data could be modeled in terms of diffusional transport. TCBQ and TFBQ were chosen as compounds to model the electron transfer behavior of biologically important quinones at the oil/water interface. The EPR and voltammetric data obtained from TCBQ/[TCBQ.sup.-[center dot]] and TFBQ/[TFBQ.sup.-[center dot]] indicated unambiguously that the two semiquinones are stable at the DCE/water interface and do not undergo immediate protonation.

A study was conducted to examine the reactivity of a quinone methide complex to strong electrophiles and nucleophiles. Rare examples of stable quinone methides and xylylenes that were stabilized by metal complexation and can be transformed into methylene arenium complexes were developed. The methylene arenium compounds can be described as a discrete resonance of a benzyl cation with a ring-localized charge stabilized through metal complexation.

A novel method for the synthesis of a series of N-heterocyclic quinones and hydroquinones was developed based on ring expansions of 4-hydroxy-4-[4-N-(benzenesulfonyl)-4-aza-1,6-alkadiynyl]cyclobutenones. The synthetic strategy involves the formation of dihydrophenanthridinediols by the thermolysis of 4-hydroxy-4-(3-N-phenyl-1-propynylamino)cyclobutenones. The method also includes the four-step synthesis of a benzophenanthridine from 4-(3-N-naphthalenyl-1-propynylamino)cyclobutenone. Assoanine was synthesized by the reaction of dimethyl squarate with indoline.

We examined the effects of the intensity of incident light and the concentrations of cyanobacterium, Synechococcus sp. UTEX2380, and an electron transfer mediator, 2-hydroxy-1,4-naphthoquinone (HNQ), on the current output of a photosynthetic electrochemical cell operated under illumination. Though the current density was higher with increasing concentration of Synechococcus sp., increase in the current density was suppressed at more than 24 [[micro]gram] chlorophyll/ml. The current density reached a maximum value at 1 mM HNQ. The current density was saturated at 50 W/[m.sup.2] probably due to reoxidation of HNQ by oxygen photosynthetically evolved. The conversion efficiency of light energy to electrical energy was 3.3%. For the analysis of energy loss for four steps in the electrochemical cell reaction, the energy loss remarkably arose from the reaction of the electron transfer chain and the high internal resistance of the electrochemical cell.

A series of 3,4-disubstituted 6,7-indolequinones and 3,7-disubstituted 4,5-indolequinone was synthesized as the model compounds for the new organic cofactor TTQ of bacterial amine dehydrogenases through the use of 1H- and 13C NMR. It was revealed that the active hydrogen and hydroxyl factors enhanced the reactivity of the cofactor in the amine oxidation-reduction. Replacement of the active hydrogens of PPQ and TPQ by a methyl compound inhibits the reactivity.

Oriented multilayers of Photosystem I from Synechocystis PCC 6803 and electron paramagnetic resonance spectroscopy were utilized to determine the orientation of the phylloquinone ring plane and the oxygen-oxygen(O-O) axis relative to the cell membrane. Results have shown that the electrostatic potential of the receptor A1 is almost similar to the prototype enzymatic configuration of the amino acids.

Resonance Raman spectroscopy of the the oxidized and semiquinone forms of flavocytochrome b2 and L-Lactate monooxygenase was utilized to describe the structural and environmental differences of the flavin ring. Data indicated that the differences have originated from slight differences in the flavin monooxygenase (FMN) orientations in the structure. Furthermore, it was indicated that the two flavoproteins differ in the N1/N5-protein interactions.

Polycyclic aromatic hydrocarbons (PAH) are environmental pollutants that are believed to cause cancer in humans by damaging DNA. By themselves they are innocuous, but in association with other compounds they may act as potent nucleases. This study aimed to identify which associations of PAH omicron-quinones render them capable of DNA scission. Results showed that NADPH, Cu(II), Cu(I), H2O2, and OH radical were necessary for PAH omicron-quinones to act as nucleases. On the other hand, addition of OH radical scavengers like mannitol, sodium benzoate and formic acid decreased both DNA strand scission and OH radical formation.

The continuous on-line monitoring of endogenous quinones has been realized for the first time in an animal model of brain ischemia induced by a vasoconstrictor peptide, endothelin-1. A microdialysis probe, implanted in the striatum of a freely moving rat, was coupled online with an amperometric thin-layer cross-flow detector with a glassy carbon working electrode operating at -200 mV vs Ag/AgCl. The instrumental setup comprised a syringe pump pulse-damper consisting of an air bubble and a silica capillary, which permitted considerable reduction of background current fluctuations and allowed improved detection limits. This original configuration allowed the quantitation of micromolar amounts of total quinones, generated from dopamine during the reperfusion period, to be readily monitored. Several operational parameters have been investigated: flow rate, presence of oxygen in the perfusion fluid, and the working potential. The selectivity of the assay toward quinones was confirmed by studying possible interfering species such as ascorbate, hydrogen peroxide, riboflavin, and thiols. The results on freely moving rats have shown that the endogenous quinone amount was directly related to dopamine concentrations. The latter was determined by HPLC from dialysate samples collected at the outlet of the on-line system. HPLC studies showed that the primary quinone, generated from dopamine by bulk electrolysis, was also found in dialysates from ischemic brain.

The chemical structures of a series of farnesylated quinones that were isolated from Aplidium longithorax were analyzed by X-ray and nuclear magnetic resonance (NMR) spectroscopy. NMR analysis of the monomeric prenylated quinone indicated the presence of three trisubstituted double bonds and seven quarternary carbons. On the other hand, spectral analysis of the dimeric prenylated quinone indicated the presence of 12 methylenes and four carbonyl groups. The longithorones also exhibited carbocylic skeletons that were derived from the cyclization of farnesyl hydroquinone.

The series of [2]rotaxanes was generated based on a template-directed synthetic process involving the reaction of an excess resorcinol with benzyl bromide. The synthetic process for the self-assembly of the novel [2]rotaxanes with hydroquinone and resorcinol rings was characterized by the LiBr-mediated formation of a phenol intermediate. The reaction of the intermediate product with tosylate also led to the formation of the benzyl-protected compound which formed the symmetrical dumbell compounds.

A novel method for the synthesis of the structural variants of (-)-ilimaquinone was developed based on the SeO2/t-BuOOH-mediated oxidation of the marine sponge metabolite. Analysis of the resulting ilimaquinone variant with new non-radioisotope-based antisecretion assay indicated that absence of protein trafficking-related activities. However, the novel assay detected a variant, amine-containing ilimaquinone derivative that retained the original biochemical activity of ilimaquinone.

A method for the facile synthesis of chrysene-5,6-diones was developed based on a convenient Lewis acid-promoted addition reaction between 1,2-naphthoquinones and 1,1-diarylethylenes. The products produced from the Lewis acid-promoted addition reaction undergo photocyclization which led to the regioselective formation of 3,12-disubstituted chrysene-5,6-diones. Furthermore, the formation of the final products was dependent on the nature of the substituents of 1,2-napthoquinone and 1,1-diarylethylenes.

Electron poor dienes such as omicron-thioquinones were synthesized by the reaction of phthalimidesulfenyl chloride with hydroxyl arenes in chloroform. The omicron-hydroxythiophthalimides obtained from hydroxyl arenes and phthalimidesulfenyl chloride were utilized as the precursors of omicron-thioquinones. Furthermore, 1,4-benzooxanthiin systems were synthesized by the trapping of the reactive intermediates with a number of different electron-rich alkenes and alkynes.

The stabilities of di(1-azulenyl)(4-hydroxyphenyl)methyl hexafluorophosphates were characterized based on the analysis of their redox potentials via cyclic voltammetry (CV). CV analysis of the redox potentials of the conjugate acids of quinone methides indicated the high stabilities and reduction potentials of the compounds. The high stabilization of the quinone methide conjugate acids was mediated by the electron-donating properties of the less hindered 4-hydroxyphenyl groups.

The electrochemical and chemical reactions of brucine following an oxidation step were investigated by cyclic voltammetry, chronocoulometry, bulk electrolysis, visible spectrophotometry, and electrospray mass spectrometry with the goal of better understanding the brucine-based determination of nitrate. The experiments were performed in acidic solution (0.010-7.0 M surfuric acid) using carbon paste, glassy carbon, and platinum electrodes. Following a two-electron oxidation ([E.sub.p] = 0.901.15 V vs Ag/AgCl), [brucine.sup.2+] reacts with water to form an aminochrome (brucichrome) plus methanol. Brucichrome undergoes a reversible two-electron reduction ([E.sup.[degrees][prime]] = 0.54 V, 0.01-7.0 M sulfuric acid) to form a hydroquinone and also slowly dimerizes. The dimer is also an aminochrome, and it, too, undergoes a reversible two-electron reduction ([E.sup.[degrees][prime]] = 0.39 V). The primary evidence for a dimeric final product comes from electro-spray mass spectrometry during electrolysis, elemental analysis, and H-NMR on a product isolated from bulk electrolysis in HCl.

UV-visible and electron paramagnetic resonance spectroscopy, supplemented with kinetic assays were done to determine an alternative mechanism of topa quinone (TPQ) formation. The results confirmed that Cu(II) is not significantly reduced when added to the apoprotein under anaerobic conditions. The data also indicated that tyrosine oxidation to yield TPQ depends only on the copper that is bound in the active site. The alternative mechanism thus identified involves the attack of an activated copper-oxygen species on a tyrosine radical intermediate.

The sequence of pqqC'BA in the genomic region of Methylobacterium extorquens AM1 and the purification of an intermediate of PQQ synthesis were described. Two open reading frames found in the sequenced region of Methylobacterium extorquens were pqqE and pqqC/D. The pqqC mutant produced an intermediate of PQQ biosynthesis which was converted to PQQ using a crude extract of E. coli cells. The intermediate was found in both the culture medium and crude extract.

A novel method for the synthesis of a series of N-heterocyclic quinones and hydroquinones was developed based on ring expansions of 4-hydroxy-4-[4-N-(benzenesulfonyl)-4-aza-1,6-alkadiynyl]cyclobutenones. The synthetic strategy involves the formation of dihydrophenanthridinediols by the thermolysis of 4-hydroxy-4-(3-N-phenyl-1-propynylamino)cyclobutenones. The method also includes the four-step synthesis of a benzophenanthridine from 4-(3-N-naphthalenyl-1-propynylamino)cyclobutenone. Assoanine was synthesized by the reaction of dimethyl squarate with indoline.

A palladium-catalyzed polyene cyclization of naphthyl triflate using (S)-(+)-BINAP as the chiral ligand was used for the first total asymmetric synthesis of (+)-xestoquinone in 68% ee. The route uses an asymmetric palladium-catalyzed polyene cyclization which forms both rings C and D while at the same time introducing the asymmetric center in a single step. A new approach for the preparation of 6,7-dihydroisobenzofurans using a Witting rearrangement on a seven-membered cyclic ether precursor is also described.

A unique pathway to the dehydrodigalloyl linker unit of agrimoniin-type ellagitannins is provided by the dimerization of orthoquinones derived from the oxidation of galloyl monoethers. These reactive yet selective galloyl-derived orthoquinones participate in various nucleophilic addition reactions with heteroatomic and carbanionic partners. Results show the accessibility and tractability of these intermediates in many significant bond-forming processes.

A simple unimolecular C-C bond scission in radical cations is used as a probe for photoinduced electron transfer reactions of chlorinated benzoquinones. THe dynamics of back-electron transfer in these two types of radical ion pairs are examined using the fragmentation rates and the quantum yields. Products with high quantum yields were observed for the triplet ion pairs formed by interception of excited state quinones, while the singlet ion pairs formed by irradiation of the charge-transfer complexes between the quinones and the donors undergo reactions with lower efficiency.

The sulfinyl group suitably regulates the diastereoselectivity of Diels-Alder reaction of (S)-2-(p-tolylsulfinyl)-1,4-benzoquinone (4a) under adequate conditions. The reaction of 1a with cyclopentadiene in a thermal environment generate a mixture of two sulfoxide adducts 4a and 4b. Stereoselectivity increases and reactivity decreases at low temperature, and the diastereoselectivity is proportional to polarity of the solvent. Cycloaddition occurs on C5-C6 and the pi-facial selectivity is enhanced in the presence of Eu(fod)3.

An operon in Bacillus subtilis is identified by subjecting the Escherichia coli strain to nucleic acid analysis, heme-specific labeling and cytochrome c absorption spectroscopy. The tricistronic operon is located about 200 degrees on the B. subtilis map. Its disruption leads to the loss of a 22-kDa cytochrome c from membrane preparations, indicating that it is closely related to cytochrome bc1 and b6f complexes.

A 1,5-biradical (III) intermediate is detected by chemically induced dynamic nuclear polarization (CIDNP) during the photocycloaddition of quadricyclane and norbornadiene with quinones. The addition reactions producing oxolanes (I) and oxeanes (II) are analyzed by measuring CIDNP and NMR spectrum. The structure and thermodynamics of I, II and III is discussed.

The electron spin density distribution and hydrogen bonding of the anionic plastosemiquinone radical Q(super .-)(sub A) of photosystem 2 of oxygenic photosynthesis are analyzed by electron nuclear double-resonance and special TRIPLE spectroscopies. One of the hydrogen bond in Q(super .-)(sub A) si parallel and the other perpendicular to the quinone ring plane.

A plausible hypothesis and a model has been proposed to facilitate the understanding of the inhibitory properties of vitamin E quinone, an anticoagulant having beneficial effects on stroke and ischemic heart disease. Vitamine E is a potent inhibitor of vitamin K-dependent carboxylase. The model supports the interpretation of the anticlotting activity associated with vitamin E. This consideration of the vitamin E as an anticlotting agent is discussed.

A site-directed mutation of Escherichia coli fumarate reductase in the (3Fe-4S)-quinone binding domain resulting in inactivation of aerobic growth possibly due to increased production of hydroxyl radicals or sensitivity to the radicals. This indicates that the (3Fe-4S) cluster may be a part of a quinone binding site or may be a factor in site interactions. The theory that oxidative damage is linked to mitochondrial dysfunction and protein modifications in aging is also supported.

Synthesized rigid porphyrin-quinone dyads show ultrafast photoinduced electron transfer having weak dependence on temperature, solvent and driving force. Rapid rate of photoinduced electron transfer and its independence from the environmental factors indicates that transfer is governed by intramolecular vibrations. Applications of the rigid dyads of this type in building blocks for complex molecular devices may be possible.

Interactions among distant residues affects electrostatic capability in immediate surroundings of photosynthetic mutant bacteria terminal electron acceptor Qb. This guarantees efficient conduction of protons through protein matrices and delivery to reduced quinones. There is a possibility of propagation of these influences over large distances by mutation-induced realignments of salt bridges within a network of residues in this area of the photosynthetic reaction center.

EPR spectroscopic studies of the influence of cyanide on the iron-quinone complex QaFe2+ at high pH values show that g=1. 98 signal due to QA-Fe2+ state slowly increases to g=2.0045, indicating the uncoupling of QA- from iron. Mossbauer spectroscopic studies show that at high pH and higher cyanide concentrations cyanide converts Fe2+ from high-spin state to a low-spin state. The reversible formation of QA-Fe2+ at low pH reveals that iron is not dissociated during pH-cyanide treatment. Increase of value at higher CN concentrations shows the binding of two or three cyanides on the iron.

1,8-difluoroanthraquinone reacts with aza-12-crown-4 and aza-15-crown-5 to give two disubstituted anthraquinones. Cyclic voltammetry analyzes the complexation of these products. Na+ forms 1:1 complexes with these quinones, whereas Li+ forms 2:1 complexes. Li+ and Na+ ions show high cation binding enhancements. This technique is also used to prepare various lipophilic diaza-12-crown-4-anthraquinone systems.

Three models having more consistent structural resemblance to the quinone form (TPQ) of a protein found in mammalian copper amine oxidase active sites are synthesized. These models differ in the nature of alkyl substituent. These quinone forms deaminate benzylamine in aqueous CH3CN, both catalytically and stoichiometrically. The pH-dependent benzenetriol to hydroxyquinone autooxidation and amine reaction with benzenetriol forms are examined to analyze aerobic autorecycling deamination.

TiCl4-containing chiral complex-enhanced Diels-Alder reactions of 1,4-benzoquinones with dienes yield products in good enantiomeric excess. A generic recrystallization sequence yields enantiomerically pure reaction products. The TiCl4 complex's mode of preparation influences the regio- and enantioselectivities of the Diels-Alder reactions.

Methylobacterium extorquens AM1 isolated mutants do not synthesize pyrroloquinoline quinone (PQQ). The complete model and phenotypic features of the mutants are derived. pqq genes of Methylobacterium extorquens AM1 correspond to pqq genes of other bacteria. The M. extorquens AM1 consists of a total of 7 pqq genes.

Picosecond and nanosecond spectroscopic studies facilitate the analysis of the photochemistry of naphthacenequinones. Kinetic studies of the reaction mechanism for irreversible decomposition of the complexes enable the assignment of reaction intermediates to the specific transient species. The data reveals that triplet states catalyze the adiabatic reaction, and excited triplet hydrogen abstraction is the pathway for decomposition.

The alpha-diazonaphthoquiones undergo Wolff rearrangement in acidic aqueous solutions, and the resulting ketene yields indene-3-carboxylic acid on hydrolysis. Benzofulvene-8,8-diol is a major reaction intermediate. Spectrophotometric studies of the carboxylic acid reveal that it has two ionization constants at 4.50 plus or minus 0.03 and 15.2 plus or minus 0.2 for OH and CH respectively. The ketene formations rate constant is 2 times 10 to the power of 10 per second under flash photolytic conditions.