In order to further examine the geometric and electronic properties associated with active sites in copper proteins, four new pentacoordinate model compounds, Zn('II)(imidH)(S)DAP (SO(,3)CF(,3)), Cu('II)(imidR)(S)DAP (SO(,3)CF(,3)), Zn('II)(imidR)(S)DAP (SO(,3)CF(,3)), and Cu('II)(imidR)(S)DAP (SO(,3)CF(,3)) containing M-N(imidazole) and M-S (thiolate) bonds have been synthesized and characterized. Through comparative spectroscopic and electrochemical studies with "Blue" cuproprotein centers, the new mononuclear copper(II) compounds have been found to not well mimic the electronic properties of the copper(II) active sites in the proteins. The mononuclear copper(II) compounds (and their zinc(II) counterparts) have also been reacted with "axially-starved" iron(III), cobalt(II), and manganese(II) Tetra- phenylporphyrin compounds to yield a new class of twelve (mu)-thiolato bimetallic complexes as model compounds for the proposed thiolate-bridged cyt. a(,3)('3+)-S-Cu(,U)('2+) active site structure of resting cyto- chrome c oxidase. The model compounds have been derived from LFe('III)(TPP) (TPP('2-) = tetraphenylporphyrinato and L = SO(,3)CF(,3)('-)) and M'('II)(imidH)(S)DAP (SO(,3)CF(,3)) or M'('II)(imidR)(S)DAP (SO(,3)CF(,3)) (M'('II) = Zn or Cu) to yield species containing LFe('III)-S-Zn('II)(imidH)- DAP ('+), LFe('III)-SCu('II)(imidH)DAP ('+), LFe('III)-S-Zn('II)(imidR)DAP ('+), and LFe('III)-S-Cu('II)(imidR)DAP ('+) cores. Furthermore, reaction of M('II)(TPP) (M('II) = Co or Mn) with M'('II)(imidH)(S)DAP (SO(,3)CF(,3)) or M'('II)(imidR)(S)DAP (SO(,3)CF(,3)) (M'('II) = Zn or Cu) has produced new model compounds containing Co('II)-S-Zn('II)(imidH)DAP ('+), Co('II)-S-Cu('II)(imidH)DAP ('+), Co('II)-S-Zn('II)(imidR)DAP ('+), Co('II)-S-Cu('II)(imidR)- DAP ('+), Mn('II)-S-Zn('II)(imidH)DAP ('+), Mn('II)-S-Cu('II)(imidH)DAP ('+), Mn('II)-S-Zn('II)(imidR)DAP ('+), and Mn('II)-S-Cu('II)(imidR)DAP ('+) centers as (SO(,3)CF(,3)('-)) salts. Through comparative magnetochemical and spectroscopic investigations of these novel heterobinuclear com- pounds with parallel studies on the enzyme active site, a cyt. a(,3)('3+)- S-Cu(,U)('2+) active site structure for the resting enzyme has been sys- tematically tested, for the first time, by a model compound approach.

The reactions and photochemistry of iron and nickel atoms and dimers with small hydrocarbons have been investigated in an argon matrix at 15 K using Fourier transform infrared spectroscopy. Atomic iron was found to interact with an acetylenic hydrogen in the first example of a transition metal hydrogen-bonding to an alkyne. With UV photolysis this complex rearranged to ethynyliron hydride, HFeC$\sb{2}$H. At higher iron concentrations a $\pi$-coordinated diiron adduct Fe$\sb{2}$(C$\sb{2}$H$\sb{2}$) was formed. Atomic nickel formed a $\pi$ complex with acetylene which photorearranged with $\lambda \geq 400$ nm irradiation to nickel vinylidene, NiCCH$\sb{2}$. Photoreversibility was demonstrated with UV irradiation. A dinickel acetylene adduct analogous to Fe$\sb{2}$(C$\sb{2}$H$\sb{2}$) was formed at higher nickel concentrations. In reactions between nickel and ethylene oxide, activation of the C-O bond by atomic nickel resulted in formation of the first unligated nickel oxometallacycle, nickelaoxetane. Upon irradiation with $\lambda \geq 500$ nm this metallacycle underwent two metathesis pathways. One pathway produced an ethylene nickel oxide $\pi$ complex NiO(C$\sb{2}$H$\sb{4}$) which subsequently rearranged to vinylnickel hydroxide, C$\sb{2}$H$\sb{3}$NiOH, with UV photolysis. Another metathesis route resulted in a methylenenickel formaldehyde $\pi$ complex, CH$\sb{2}$Ni(H$\sb{2}$CO), which rearranged upon $\lambda \geq 400$ nm irradiation to hydridonickelmethyl carbonyl, HNiCH$\sb{3}$(CO) decomposed to methane and nickel carbonyl with UV photolysis. In studies of nickel with cyclopropane in an argon matrix, atomic nickel inserted into a C-C bond of cyclopropane to form nickelacyclobutane. Irradiation with $\lambda \geq 500$ nm caused metathesis of this metallacycle and formation of methylenenickel ethylene $\pi$ complex, CH$\sb{2}$Ni(C$\sb{2}$H$\sb{4}$). CH$\sb{2}$Ni(C$\sb{2}$H$\sb{4}$) rearranged to vinylnickelmethyl, C$\sb{2}$H$\sb{3}$NiCH$\sb{3}$, which decomposed and released methane upon extended UV photolysis.

The reaction of Pb(OAc)$\sb2$ or PbCl$\sb2$ with K (HFe(CO)$\sb4$) results in formation of (Et$\sb4$N) $\sb2$ (Pb$\{$Fe$\sb2$(CO)$\sb8\}\{$Fe(CO)$\sb4\}\sb2$) in high yield based on iron. This complex has been structurally characterized and contains a central Pb$\sp{4+}$ atom bound to two (Fe(CO)$\sb4$) $\sp{2-}$ ligands and one (Fe$\sb2$(CO)$\sb8$) $\sp{2-}$ group (Fe-Fe = 2.617(5)A). (Et$\sb4$N) $\sb2$ (M$\{$Fe$\sb2$(CO)$\sb8\}\{$Fe(CO)$\sb4\}\sb2$) reacts with CO and MCl$\sb2$ with excess K (HFe(CO)$\sb4$) to yield products which are formulated as (Et$\sb4$N) $\sb2$ (M$\{$Fe(CO)$\sb4\}\sb2$) on the basis of analytical and spectroscopic data. GeI$\sb2$ is unreactive towards K (HFe(CO)$\sb4$), but when mixed with (Et$\sb4$N) $\sb2$ (Fe$\sb2$(CO)$\sb8$) formation of the novel complex (Et$\sb4$N) $\sb2$ (Fe$\sb3$(CO)$\sb9(\mu\sb3$-CO)$\{\mu\sb3$ - GeFe(CO)$\sb4\}$) occurs. When GeCl$\sb4$ is treated with (Et$\sb4$N) $\sb2$ (Fe$\sb2$(CO)$\sb8$) formation of (Et$\sb4$N) $\sb2$ (Fe$\sb3$(CO)$\sb{11}$) is observed with no evidence of a germanium-containing cluster. These mixed metal anions are oxidized by (Cu(CH$\sb3$CN)$\sb4$) (BF$\sb4$) to form the corresponding neutral spirocyclic M (Fe$\sb2$(CO)$\sb8$) $\sb2$ (M = Sn, Ge, Pb) species. A single crystal X-ray diffraction structure was obtained for the complex Pb (Fe$\sb2$(CO)$\sb8\rbrack\sb2$ (Fe-Fe = 2.90(2)A). Reduction of Ge (Fe$\sb2$(CO)$\sb8\rbrack\sb2$ in benzene or CH$\sb2$Cl$\sb2$ led to the recovery of (Et$\sb4$N) $\sb2$ (Fe$\sb3$(CO)$\sb9(\mu\sb3$-CO)$\{\mu\sb3$-GeFe(CO)$\sb4$). (Et$\sb4$N) $\sb2$ (Pb$\{$Fe$\sb2$(CO)$\sb8\}\{$Fe(CO)$\sb4\}\sb2$) or (Et$\sb4$N) $\sb2$ (Pb$\{$Fe(CO)$\sb4\}\sb2$) are recovered from reduction of Pb (Fe$\sb2$(CO)$\sb8$) $\sb2,$ depending on the solvent used. Periodic trends were examined by utilizing bismuth as the main group element. The reaction of NaBiO$\sb3$ with K (HFe(CO)$\sb4$) resulted in isolation of (Et$\sb4$N) $\sb3$ (Bi$\{$Fe(CO)$\sb4\}\sb4$) in which a central Bi$\sp{5+}$ atom is tetrahedrally surrounded by four (Fe(CO)$\sb4$) $\sp{2-}$ ligands. This complex decomposes in the presence of gaseous HCl to produce up to 1 mole of H$\sb2$ per mole of cluster via intermediate formation of H$\sb2$Fe(CO)$\sb4.$ Refluxing NaBiO$\sb3$ with Fe(CO)$\sb5$ led to the isolation of (Et$\sb4$N) (BiFe$\sb3$(CO)$\sb9(\mu\sb3$-CO)) which is isoelectronic with (Et$\sb4$N) $\sb2$ (Fe$\sb3$(CO)$\sb9(\mu\sb3$-CO)$\{\mu\sb3$-GeFe(CO)$\sb4\}$) and contains a triangle of iron atoms capped by a bismuth atom on one face and a CO group on the other (Fe-Fe = 2.642(7)A). When (Et$\sb4$N) (BiFe$\sb3$(CO)$\sb9(\mu\sb3$-CO)) is treated with CO, an extensive rearrangement occurs leading to formation of (Et$\sb4$N) $\sb2$ (Bi$\sb4$Fe$\sb4$(CO)$\sb{13}$) in which there is a central tetrahedron of bismuth atoms attached to iron carbonyl fragments. This complex is the first "Zintl-metal carbonylate" to be reported. (Abstract shortened with permission of author.)

The vapor compositions above graphite, tantalum carbide and tungsten carbide together with the chemical reactions of C$\sb1$, C$\sb2$, and C$\sb3$ have been studied by the techniques of CW laser vaporization, matrix isolation, and FTIR spectroscopy. The carbon species were scavenged by cocondensing reactive gases (N$\sb2$, H$\sb2$, O$\sb2$, CO and H$\sb2$O) with the vapors of graphitic samples in argon or nitrogen matrices. Products were identified from their infrared spectra. Photolysis and annealing studies were also conducted to detect reaction intermediates, formation of carbon clusters, and metastable C$\sb1$, C$\sb2$ and C$\sb3$ adducts with the added reactants. From these experiments CO was shown to be potentially the most useful scavenger molecule, since it reacted with both C$\sb1$ and C$\sb2$ to form C$\sb2$O and C$\sb3$O, respectively. CO also reacted with C$\sb3$ to form an adduct, which rearranges upon photolysis to form C$\sb4$O, a previously unknown molecule. Its identity was confirmed by isotopic studies and comparison of its vibrations to those of related molecules, C$\sb3$O, C$\sb2$O and CO. In H$\sb2$O/carbon studies, only C$\sb3$ reacted with H$\sb2$O upon cocondensation to form an adduct. In O$\sb2$/carbon studies, the formation of CO$\sb2$ and CO has been explained in terms of reactions of C$\sb1$ and C$\sb2$, respectively. At high O$\sb2$ concentrations the observance of O$\sb3$ was explained as a reaction of C$\sb1$ with dimer of O$\sb2$ to form CO and O$\sb3$. These results were supported by the decrease of CO$\sb2$ as the O$\sb2$ concentration was increased. In H$\sb2$/carbon studies only C$\sb2$H$\sb2$ was detected upon either cocondensation or photolysis. Therefore, it is suggested that only C$\sb2$ reacts with H$\sb2$ on a matrix surface at 12$\sp\circ$K. When graphite, TaC and WC samples were laser vaporized into a nitrogen matrix, the C$\sb1$ concentration was detected by the formation of CNN. By measuring the CNN to C$\sb3$ peak area ratio and comparing it to that for graphite, the activity of carbon in WC was determined to be 0.4, while the activity of carbon TaC was determined to be 0.2. The IR frequencies of the C$\sb4$, and C$\sb6$ and C$\sb9$ carbon clusters, previously assigned by Weltner, were confirmed in this study. (Abstract shortened with permission of author.)

A number of significant research accomplishments have been made concerning the synthesis of new solid state materials that have interesting and important structural chemistry and physical properties; namely compounds with mixed TiO$\sb6$ octahedra and XO$\sb4$ (X = Si and P) tetrahedra: BaTi$\sb2$(P$\sb2$O$\sb7)\sb2$, A$\sp{\rm I}$TiP$\sb2$O$\sb7$ (A$\sp{\rm I}$ = Li, K, Cs, Rb), and TiP$\sb3$SiO$\sb{11}$. The LISICON series: Li$\sb{1 + x}$Ti$\sb2$(PO$\sb4)\sb3$ (0 $\le {x} \le$ 2), and oxo compounds with novel quasi-two-dimensional fused TiO$\sb6$ framework: La$\sb4$Ti(Si$\sb2$O$\sb7)\sb2$(TiO$\sb2)\sb{\rm 4m}$ (m = 1, 2) series have also been prepared and studied. For the first time, LISICON phases provide a series of compounds with pseudo-one-dimensional channel structures for systematic ionic conductivity and structure relationship studies. The oxo compound series possesses a quasi-two-dimensional structural property in that the low-valent conducting TiO$\sb6$ octahedral (rutile) framework is sandwiched by insulting oxosilicate slabs. Structurally, the preserved Ti-O-Ti and Ti-Ti linkages in the fused rutile frameworks are deemed important to the mechanistic studies of the transport properties which are induced by conduction electrons. In the exploratory syntheses of the above compounds, a conventional high-temperature solid-state ceramic method, and a molten salt flux crystal growth method have been employed. The structures of these compounds were characterized by both single crystal and powder X-ray diffraction techniques. The Weissenberg film technique was employed for the crystallographic studies. Other techniques for the structure/property characterization were also used. It has been demonstrated that the reduced titanium silicates and phosphates are new and fruitful areas of research which provides us with some insight and new direction towards the success of the synthesis of compounds with low-dimensional structures. Our success offers opportunities for finding structural models to study many unusual physical phenomena including superconductivity. Ultimately this research should lead us towards a better understanding of the structure, bonding and property correlations of metallic oxides and advanced materials.

New methods for synthesizing poly(carbon monofluoride) (CF$\sb{\rm X})\sb{\rm n}$ and tetracarbon monofluoride C$\sb4$F are reported. Pyrolytic graphite has been fluorinated and a new compound, graphite oxyfluoride, has been prepared. Poly(carbon monofluoride) has been prepared in a flow reactor, in a fluidized bed reactor, and in a high pressure bomb reactor and tetracarbon monofluoride has been prepared by a high pressure bomb technique. Some new structural data are presented for poly(carbon monofluoride). A new method for controlling the reaction of elemental fluorine with hydrocarbons is described. The rate of reaction between fluorine and hydrocarbons has been so successfully controlled that direct fluorination appears to be not only practical but the best method available for preparing fluorocarbons. Anthracene, tetracene, pentacene, p-dichlorobenzene, naphthalene, coronene, ovalene and decacyclene have been fluorinated at room temperature to yield the corresponding perfluoroalicyclic fluorocarbons in very high yields approaching 100%. The reactions of elemental fluorine with finely powdered hydrocarbon polymers and paraffins have been carefully controlled so that the products of the reactions are perfluorocarbon polymers and perfluoroparaffin fluorocarbon materials. This process constitutes a new approach to the synthesis of fluorocarbon polymers. Polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyacrylamide and n-dotricontane, CH$\sb3$-(CH$\sb2$)$\sb{30}$-CH$\sb3$ have been fluorinated to yield polytetrafluoroethylene, polyhexafluoropropylene, perfluoroperhydropolystyrene, perfluoropolyacrylonitrile, perfluoropolyacrylamide and perfluoro n-dotricontane. High yields approaching 100% have been obtained. This direct technique for fluorination of hydrocarbons and related plastics is called the La-Mar process. The reactions of sodium borohydride, potassium borohydride, lithium borohydride and lithium aluminum hydride with elemental fluorine have been investigated. The products obtained are sodium tetrafluoroborate, NaBF$\sb4$; potassium tetrafluoroborate, KBF$\sb4$; lithium tetrafluoroaluminate, LiAlF$\sb4$. This direct fluorination process establishes a new preparation for the fluoborates and has produced the new compound lithium tetrafluoroaluminate. Yields near 100% have been obtained. The controlled reaction of elemental fluorine with two $\beta$-tri-chloro-borazines is reported. $\beta$-trichloroborazine and $\beta$-trichloro-N-triphenyl-borazine are fluorinated to yield various fluorochloro derivatives under very mild conditions, and a large number of new highly fluorinated species under vigorous conditions. Some of the new species reported are $\beta$-trichloro-N-trifluoro-borazine, hexa-fluoro-borazine, and $\beta$-trichloro-N-perfluorocyclohexyl-borazine. These molecules are believed to be the first N-fluorinated borazines to be reported.

Structural studies on solvated adducts of bismuth (III) chloride have demonstrated the ability of the main group element to form multiple bonding contacts, giving "hypervalent" complexes. Similar interactions are observed in almost all aspects of the chemistry of the heavy main group elements. The reaction of $\rm \lbrack Bi\sb2Co\sb4(CO)11\rbrack\sp{1{-}}$ with $\rm Mo(CO)\sb3(\eta\sp6$-$\rm C\sb6H\sb5Me)$ in tetrahydrofuran yields an unidentified cluster product which, upon slow oxidation with molecular dioxygen or mild metal-organic oxidants yields the two large cluster species, $\rm \lbrack Bi\sb4CO\sb9(CO)\sb8(\mu$-$\rm CO)\sb8\rbrack\sp{2{-}}$ and $\rm \lbrack Bi\sb8Co\sb{14}(CO)\sb{12}(\mu$-$\rm CO)\sb8\rbrack\sp{2{-}}.$ These cluster products contain arrays of metal atoms in the cluster framework which are reminiscent of close-packed solid-state intermetallics. Halogenation of the bismuth-iron cluster $\rm \lbrack Bi\sb4Fe\sb4(CO)\sb{13}\rbrack\sp{2{-}}$ has been performed using the phosphine halide reagent, MePCl$\sb2.$ With the addition of one equivalent of the reagent, two compounds are produced in an approximately 3:1 ratio, respectively: $\rm \lbrack Fe\sb2(CO)\sb6(\mu$-$\rm H)Bi\sb2\{\mu$-$\rm Fe(CO)\sb4\}\rbrack\sp-$ and $\rm \lbrack Bi\sb3Cl\sb4(\mu$-$\rm Cl)\sb4\{\mu\sb3$-$\rm Fe(CO)\sb3\}\rbrack\sp{3{-}}.$ Upon the addition of a second equivalent of reagent, the latter compound apparently decomposes; however the former is converted into the related dichloro-cluster, $\rm \lbrack Fe\sb2CO)\sb6(\mu$-$\rm H)Bi\sb2(\mu$-$\rm Cl)\sb2\rbrack\sp-.$ Addition of yet more reagent results in the formation of the bismuth chloride-iron carbonyl adduct $\rm \lbrack Bi\sb2Cl\sb4(\mu$-$\rm Cl)\sb2\{ \mu$-$\rm Fe(CO)\sb4\}\rbrack\sp{2{-}}$ at the expense of the dichloride cluster. This latter complex may also be produced quantitatively by reaction of $\rm \lbrack Fe(CO)\rbrack\sp{2{-}}$ with two equivalents of BiCl$\sb3$ in MeCN. The reaction of the tellurium-iron cluster $\rm Te\sb2Fe\sb3(CO)\sb9$ with SO$\sb2$Cl$\sb2$ yields a variety of products, depending on the reaction stoichiometry and the solvent employed in the synthesis. In CH$\sb2$Cl$\sb2$ at a ratio of 1:2, respectively, the large dimeric complex $\rm \lbrack Fe\sb2(CO)\sb6(\mu$-$\rm Cl)(\mu$-$\rm TeCl)\sb2\rbrack\sb2\lbrack Te\sb2Cl\sb{10}\rbrack$ is formed, which decomposes in solution to the Zintl-ion complex $\rm \lbrack Fe\sb2(CO)\sb6(\mu$-$\rm TeCl\sb2)(\eta\sp2$-$\mu\sb2$-$\mu\sb2$-Te$\sb4 )\rbrack.$ In MeCN at a ratio of 1:1, the previously reported tetrahedral cluster Te$\sb2$Fe$\sb2$(CO)$\sb6$ is produced, which reacts with additional reagent to yield a complex thought to be $\rm \lbrack Fe\sb2(CO)\sb6(\mu$-$\rm TeCl)\sb2(\mu$-$\rm Cl)\rbrack$ from spectroscopic evidence. This cluster in turn decomposes in solution to $\rm \lbrack Fe\sb2(CO)\sb6(\mu$-$\rm TeCl\sb2)(\eta\sp2$-$\mu\sb2$-$\mu\sb2$-Te$\sb4)\rbrack$ like the first compound. Different products result if the solvent system is again changed to SO$\sb2$/Me$\sb2$CO at $-$30$\sp\circ$C. Although these unstable products have not been structurally characterized, a fair amount of other analytical and spectroscopic data have been obtained. The bromination of Te$\sb2$Fe$\sb3$(CO)$\sb9$ with CBr$\sb4$ has also been performed in MeCN, giving initially Te$\sb2$Fe$\sb2$(CO)$\sb6;$ however, upon reaction with more CBr$\sb4$ over a few weeks time at 0$\sp\circ$C, the novel cubane-like cluster $\rm \lbrack Fe\sb3(CO)\sb9Te\sb4(\mu\sb3$-$\rm CTeBr\sb4)\rbrack$ results in low to moderate yields of 30-65% based on Te. Theoretical calculations by the extended Huckel method have been performed on some model systems, and have provided valuable insight into the underlying bonding arrangements giving rise to the sometimes-unexpected stability and structural features of these products.

The phase transitions of some orientationally-disordered solids (plastic crystals) have been studied by DSC, and variable-temperature-IR and -Raman spectroscopy. The adamantane derivatives, 1-bromoadamantane (1-C$ sb{10}$H$ sb{15}$Br) and 2-chloroadamantane (2-C$ sb{10}$H$ sb{15}$Cl) were found to have two phase transitions, at 283 K and 312 K for the former and 227 K and 242 K for the latter; 2-bromoadamantane (2-C$ sb{10}$H$ sb{15}$Br) and 1-chloroadamantane (1-C$ sb{10}$H$ sb{15}$Cl) only exhibited one phase transition each, at 281 K and 245 K, respectively. Only one phase transition was found for 9-bicyclononanone (9-C$ sb9$H$ sb{14}$O) at 299 K. Oxanorbornane (C$ sb6$H$ sb{10}$O), a liquid, was found to have three phase transformations (192, 234, and 245 K), with the 234 K transition being metastable. Another phase transition, which is both time dependent and rate-of-cooling dependent, was found for o-carborane (o-C$ sb2$B$ sb{10}$H$ sb{12}$) by variable-temperature infrared spectroscopy. The infrared and Raman spectra of the adamantane derivative, 2-adamantanone (2-C$ sb{10}$H$ sb{14}$O), revealed that a new low-temperature phase was present after cycling. / Micro-Raman pressure spectroscopy was used for the first time in the study of phase transitions of plastic crystals. The same phase transformation of 1-chloroadamantane that occurred at 245 K and 1.01 bar was found to occur at 295 K and $ sim$5 kbar. The o-carborane phase transition which took place at 274 K and 1.01 bar also takes place at 295 K and $ sim$10 kbar. Finally, 2-chloroadamantane, which exhibited two phase transitions (227 K and 242 K) at atmospheric pressure, also underwent phase transformations at room temperature and 3 and 11 kbar, respectively.

AbstractA gallium (III) protoporphyrin IX model as a heme analog, capable of forming a reciprocal dimer analogous to the malaria pigment hemozoin, is synthesized and characterized. This simple metal substitution yields a molecule which is very soluble and easily handled in air, recommending itself to studies of the analogue in solution, particularly in studies of hemozoin formation and of associations with known antimalarials which target its formation. Hemozoin formation is regarded as a heme detoxification pathway in the parasite and its mechanism of formation is a subject of current scientific debate. Disrupting this process and arresting the formation of hemozoin leads to free heme accumulation and death of the parasite. The gallium porphyrin model described here allows for an exact determination of detailed structural information of the formation of bound complexes of metalloporphyrin and for a survey of antimalarial agents which have been efficacious in the past and present. This will provide useful information concerning the direct interaction between the drug and the heme or hemozoin in the acidic aqueous medium of the digestive vacuole of the malaria parasite. / AbstraitNous avons développé la protoporphyrine IX de gallium (III) afin de l'utiliser en analogie à l'hème, qui est capable de former un dimère réciproque avec le pigment malarique hémozoïne. Cette substitution directe du métal produit une molécule qui est facilement dissolue et qui peut être manipulé dans l'air, ce qui demande son étude en solution. Notamment, les études sur la formation de l'hémozoïne et de son association avec les antipaludiques qui l'inhibent sont d'intérêt. La formation de l'hémozoïne est perçue comme étant une voie métabolique qui mène à la détoxification de l'hème pour le parasite et le mécanisme de sa formation est un sujet contesté. L'interruption de celle-ci et l'arrestation de la formation de l'hémozoïne qui résulte engendre une accumulation de hème qui tue éventuellement le parasite. Nous avons utilisé notre modèle de porphyrine à base de gallium pour élucider de l'information structurale détaillée sur les métalloporphyrines liées à plusieurs antipaludiques qui ont déjà été efficaces et qui le sont toujours. Ces études procureront de l'information utile sur les interactions directes de ces antipaludiques avec l'hème ou l'hémozoïne dans le milieu acide aqueux de la vacuole digestive du parasite qui cause le paludisme.

Network formation using chlorotris(diethylamino)silane [ClSi(NEt 2)3], tetrakis(dimethylamino)silane [Si(NMe2) 4], and tetrakis(diethylamino)tin [Sn(NEt2)4], and NLO-active chromophore was investigated to yield inorganic-organic hybrid materials for 2nd-order nonlinear optics. In contrast to hybrids obtained from Si(NEt2)4, those prepared from ClSi(NEt 2)3 and Sn(NEt2)4 were insoluble even in high boiling solvents. Facile hydrolysis of the NLO-active dye was found to occur in these hybrids due to the catalysis of HCl and the high reactivity for ClSi(NEt2)3 and Sn(NEt2)4 respectively. Due to the insolubility of the networks, it was not possible to determine if the dye present in these networks was physically trapped or covalently bound to the inorganic matrix. It was observed that the method used for the hydrolysis of M--NR2 bond played an important role in the stability of the Si--OR bond for hybrids prepared from Si(NMe 2)4 and Sn(NEt2)4.