Biosynthesis of chlorophylls from protoporphyrin IX

A review of the biosynthesis of chlorophylls and bacteriochlorophylls from protoporphyrin IX with 235 references. The literature on the enzymes magnesium chelatase, S-adenosyl-L-methionine:magnesium protoporphyrin IX O-methyltransferase, magnesium-protoporphyrin IX monomethyl ester oxidative cyclase, protochlorophyllide oxidoreductase, chlorophyll synthase, bacteriochlorophyll synthase, protochlorophyllide 8-vinyl reductase and chlorophyll a oxidase from 1989 is discussed.     

A comparison of protoporphyrin IX and protoporphyrin IX dimethyl ester as a photosensitizer in poorly differentiated human nasopharyngeal carcinoma cells

Protoporphyrin IX dimethyl ester (PME), a dimethyl esterification of protoporphyrin IX (PpIX), exhibits higher intracellular uptake into NPC/CNE2 cells, a poorly differentiated human nasopharyngeal carcinoma, than does PpIX. Phototoxicity studies reveal PME to be a more potent photosensitizer than is PpIX, at the early and late incubation time points. Correlating phototoxicity with subcellular localization indicates that PME is a more potent photosensitizer when its primary target of photodamage is mitochondria. Also, additional targeting of lysosome enhances phototoxicity.     

Three new dinuclear silver(I) complexes derived from pyrazolyl type ligands

Three NNN type ligands derived from 2,6-dichlorpyroidine, pyrazol and 3,5-dimethylpyrazole and their silver complexes were prepared in methanol media. The complex structures were characterized using IR spectroscopy, X-ray diffraction and elemental analysis. X-ray studies showed the complexes to be dimeric in structure. The two nitrogen atoms of the ligand coordinated the first Ag(I) ion whereas the second Ag(I) ion was coordinated by the third nitrogen donor. The nitrate structure was not ionic in a done of its oxygen atoms coordinated an Ag(I) ion. The Ag(I) ion was seen to be situated in a deformed tetrahedral coordination sphere. Thermogravimetric studies showed the complexes to decompose similar to explosive material. The decomposition temperature was observed to increase with increasing hydrogen atoms in the structure.     

A DFT study on the vibrational spectroscopy of protoporphyrin IX

Infrared and Raman spectra of protoporphyrin IX were recorded. DFT quantum chemical calculations were performed. Optimised molecular geometry, electric charge distribution, vibrational force constants were computed. The normal coordinate analysis and the scaling of the force constants yielded all the necessary data for the simulation of the infrared and Raman spectra and the potential energy distribution calculations. The result was the interpretation of all vibrational modes of the molecule. Conclusions were drawn from the difficulties arisen during the assignment of the vibrational spectra of such large molecules.     

Evaluation on the adsorption capabilities of new chemically modified polymeric adsorbents with protoporphyrin IX

A novel stationary phase — phenylaminopropyl (PLA) bonded silica — is proposed for anion-exchange chromatography. Low basicity (pK_a about 2.5) attached to silica phenylaminopropyl groups allows a variation of surface density of protonated sites in the pH range from 2 to 5. This enables us to use the same column for the separation of anions having different affinity to anion-exchangers. The effect of mobile phase pH on conditional capacity of PhA-silica was studied. The hypothesis on dependence of ion-exchange selectivity on the column capacity is discussed. Suitability of PhA-silica for ion-chromatographic separation of organic and inorganic anions at different pH values of eluent was demonstrated.     

Dithiocarbene complexes derived from CS2 -bridged dinuclear complexes

Stable dithiocarbene complexes {CP(CO)₂FeC(SCH₃)[SML_n]}⁺ (ML_n = Re(CO)₅, Fe(CO)₂Cp) are formed when monodentate ferrodithiocarboxylate—metal complexes Cp(CO)₂FeC(S)[SM′L_n] (Cp  η⁵ -C₅H₅) are treated with CH₃SO₃CF₃.     

A new oxamido-bridged dinuclear copper(II) complex with large antiferromagnetic exchange interactions

A new oxamido-bridged dinuclear compound [Cu₂(µ-pmox)(DMF)₄]?·?2ClO₄ (1) (H₂pmox?=?N,N′-bis-(2-methylpyridyl)oxalamide, DMF?=?dimethylformamide) was synthesized and structurally characterized. The five-coordinate Cu(II) is bridged by oxamido groups and further cross-linked by C–H···O hydrogen bonds between the uncoordinated oxygen of perchlorate and methyl of DMF. The complex was also characterized by infrared spectroscopy and magnetic measurement. The copper complex exhibits strong antiferromagnetic interactions via the trans oxamido bridge with J of ?414?cm^?1, where J is the exchange parameter in the isotropic Hamiltonian H?=??JS₁S₂.     

Irradiation of the porphyrin causes unfolding of the protein in the protoporphyrin IX/beta-lactoglobulin noncovalent complex

Porphyrins such as protoporphyrin IX (PPIX) are known to occasionally cause conformational changes in proteins for which they are specific ligands. It has also been established that irradiation of porphyrins noncovalently intercalated between bases or bound to one of the grooves can cause conformational effects on DNA. Conversely, there is no evidence reported in the literature of conformational changes caused by noncovalently bound PPIX to globular proteins for which the porphyrin is not a specific ligand. This study shows that the irradiation of the porphyrin in the PPIX/lactoglobulin noncovalent complex indeed causes a local and limited (approximately 7%) unfolding of the protein near the location of Trp19. This event causes the intrinsic fluorescence spectrum of the protein to shift to the red by 2 nm and the average decay lifetime to lengthen by approximately 0.5 ns. The unfolding of lactoglobulin occurs only at pH >7 because of the increased instability of the protein at alkaline pH. The photoinduced unfolding does not depend on the presence of O2 in solution; therefore, it is not mediated by formation of singlet oxygen and is likely the result of electron transfer between the porphyrin and amino acid residues.     

New chiral selenium electrophiles derived from functionalized terpenes

A convenient method for the synthesis of optically active dialkyl diselenides derived from bicyclic terpenes functionalized with hydroxy, etheral, sulfide, and selenide groups is described. The diselenides were used for a synthesis of chiral electrophilic selenium reagents, then in the asymmetric selenenylation of styrene and selenocyclization with o-allylphenol. The influence of nonbonding selenium-heteroatom interactions in the generated organoselenium electrophiles on the stereoselectivity of an addition reaction has been investigated. Calculations by a DFT method on a B3LYP (6-311G (d)) level, confirmed the existence of nonbonded selenium-heteroatom interactions in the investigated systems.     

A cationic hydro­xo-bridged dinuclear gallium complex

The crystal structure of μ-hydro­xo-bis{[N-iso­propyl-2-(isopropyl­amino)­tropon­imino-N,N′](methyl)gallium(II)} tetrakis(pentafluorophenyl)borate (troponimine is 2,4,6-cycloheptatrien-1-imine), [Ga₂(C₁₄H₂₂N₂)₂(OH)]B(C₆H₅)₄, is discussed. The two (ⁱPr₂-ATI)GaMe (ATI is aminotroponimime) units of the dinuclear cation are linked by a bridging hydro­xo group and are both slightly twisted from planarity.     

Formation and utility of oxasilacyclopentenes derived from functionalized alkynes

Oxasilacyclopentenes were shown to be synthetically useful masked allylic alcohols constructed in high yields and regioselectivities from terminal and internal alkynes. Several functional groups were shown to be tolerated utilizing silver-catalyzed silacyclopropenation of alkynes. In situ insertion of various carbonyl compounds into silacyclopropenes afforded regioselective formation of oxasilacyclopentenes. Elaboration of the oxasilacyclopentenes displayed the synthetic utility of these substrates. Both diastereoselective hydrogenation and Diels-Alder reactions utilizing the vinylsilane functionality demonstrated the reactivity and synthetic utility of oxasilacyclopentenes.     

Synthesis and structure of new dinuclear palladium complex containing no bridging ligands

Oxidation of the mononuclear semiquinonediimine complex [(NPh)(NH)C₆H₄]₂Pd with silver trifluoromethanesulfonate afforded the diamagnetic dinuclear dicationic palladium complex {[(NPh)(NH)C₆H₄]₂Pd}₂(O₃SCF₃)₂ with a Pd...Pd distance of 3.267(1) . The complex was structurally characterized, and its spectroscopic and electrochemical properties were studied.     

Synthesis of functionalized pentacenes from isobenzofurans derived from C-H bond activation

The synthesis of unsymmetric functionalized pentacenes from 1,4-anthraquinones and functionalized isobenzofurans, which were prepared by transformation via C-H bond activation, was successfully accomplished. Examples of the synthesis of pentacenes with functional groups at the 5-position are still rare. These obtained functionalized pentacenes are highly soluble in hexane, toluene, and THF.     

A new boron-selective resin derived from guar gum

A boron-selective resin has been prepared by cross-linking of a natural plant hydrocolloid (the polysaccharide guaran from guar seeds). Concentration and separation of boron can be achieved on this resin through completing of boron with the cis-hydroxyl groups in the polymer. The method has been applied to the determination of boron.     

A new hybrid material constructed from octamolybdate anion and neutral dinuclear copper units

A new organic–inorganic hybrid material constructed from octamolybdate anion and neutral dinuclear copper(I) units, H₄{[Cu₂(ophen)₂]₂[Mo₈O₂₆]}[Cu₂(ophen)₂] · H₂O (1) (Hophen =2-hydroxy-1,10-phenanthroline), has been prepared under hydrothermal condition and characterized by elemental analysis, IR, XPS, TGA and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P 1, with a = 9.9091(8), b = 13.3981(8), c = 14.8266(10) Å, α = 84.6310(10), β = 83.0620(10)°, γ = 77.7800(10), V = 1905.0(2) ų, Z = 1. Compound 1 contains a centrosymmetric polyoxoanion {[Cu₂(ophen)₂]₂[Mo₈O₂₆]}^4?, in which the β-[Mo₈O₂₆]^4? is bisupported by two copper(I) coordination groups through the terminal oxygen atoms. The discrete molecules of 1 are extended into a 3-D supramolecular array through C–H ··· O hydrogen bonds and strong aromatic π–π stacking contacts.     

Functionalized macrocycles from functionalized tetra-amines: pendent-arm macrocycles derived from dichloropivalic acid

Reaction between ethane-1,2-diamine and 3,3'-dichloropivalic acid results in different, isomeric tetra-amine derivatives, one a tetraamino carboxylic acid and the other a carboxamidotriamino alcohol, depending upon reaction conditions. Intended conversion of the Cu(II) complex of the former to a cyclam-like macrocycle through reaction with nitroethane and formaldehyde results in isolation of derivatives of both the former and the latter. This can be rationalized by assuming the intermediacy of an azetidinone, a species similar to that seen in simpler reactions of dichloropivalates. A single reaction thereby provides pendent-arm macrocycles where one has an electrophilic and the other a nucleophilic substituent. Parallel chemistry is not seen in the reaction between propane-1,3-diamine and 3,3'-dichloropivalate.