Of o-phenanthroline

Charge-transfer absorption is important because it produces very large absorbances, providing for a much more sensitive analytical method. One important example of a charge-transfer complex is that of o-phenanthroline with Fe +, the UV/Vis spectrum for which is shown in Figure 10.17. Charge-transfer absorption in which the electron moves from the ligand to the metal also is possible. 

Since o-phenanthroline is present in large excess (2000 xg of o-phenanthroline for 100 xg of Fe +), it is not likely that the interference is due to an insufficient amount of o-phenanthroline being available to react with the Fe +. The presence of a precipitate in the sample cell results in the scattering of radiation and an apparent increase in absorbance. Since the measured absorbance is too high, the reported concentration also is too high. 

When M is Mo or W, the substitution reaction follows a two-term rate expression and in addition there is some replacement of the dipyridyl or 1,2-diamino-2-methyl propane but not of o-phenanthroline. The proportion of bidentate replacement to CO replacement is practically independent of the concentration... 

Gordon and Wahl have used the radioisotope "°Ag as a tracer for a study of the exchange of silver between Ag(II) and Ag(I) in acidic media. The precipitation of Ag(phen)2(C104)2, brought about by the addition of o-phenanthroline, formed the basis of the separation method. The experimental data were obtained using a... 

The reaction, as studied by Betts ° , was followed by measuring the amount of Fe(n) formed as a function of time, aliquots of the reaction mixture being quenched by a solution of o-phenanthroline at pH 4. At constant acidity and ionic strength the reaction is first-order in both Fe(IIl) and U(IV), viz. 

Fig. 5. Effect of o-phenanthroline on photophobic response (open circles) and photokinesis (closed circles) of Phormidium uncinatum. Abscissa o-phenanthroline concentration in mol Ordinate response in % of the uninhibited control (after Nultsch and Jeeji-Bai104))...

Through the presence of aromatic or pseudoaromatic groups in the molecule (tetraphenylborate and related derivatives, the tetraphenyl-arsonium ion, cationic triphenylmethane dyes, complexes of o-phenanthroline with divalent nickel or ion, where the hydrophobicity is increased by further substitution by a hydrophobic group on the pseudoaromatic nucleus). 

Ferroin indicator - slowly dissolve 3.71 g of o-phenanthroline and 1.74 g FeS04.7H20 in 250 ml water. 

Determination of Azide as NaNt. Pipette a 25 ml portion of the sample into a 500 ml Erin flask and dil with w to 150-200 ml. Titrate with 40% sulfuric acid to just fo the phpht end-point, not overrunning it. Add N/10 ceric sulfate soln in 5 ml portions until the soln becomes deep yel, indicating an excess of ceric sulfate. Record the exact amt used. Add 10 ml of 40% sulfuric acid and 2 drops of o-phenanthroline indicator (prepd by dissolving 14.85 g of o-phenanthroline monohydrate, CiaHsNa HaO in 1 1 of 0.025 M freshly prepd ferrous sulfate... 

Reaction of o-phenanthroline with the anions Co(mnt) and Co(tfd)J leads46 to addition and formation of octahedral complexes of type (31). 

The DNase activity of o-phenanthroline-Cu2+ complex bound to DNA in the presence of H202 is also triggered by thiols (Chap. 12). 

The redox chemistry of PQQ has been investigated by a number of research groups. Duine et al. [14,15] performed potentiometric titrations of PQQH2 at several pHs and measured the redox potential of PQQ/PQQH2. Eckert et al. [16,17] compared the redox properties of PQQ with those of o-phenanthroline quinones. Kano et al. [18] performed cyclic voltammetry at acidic pH. Bergethon [19] investigated the amperometric detection of PQQ as a tool for HPLC. From pulse radiolysis experiments, McWhirter and Klapper [20] derived a value of -122 mV (NHE) for Em PQQ/PQQH at pH 7, as compared to the value of - 218 mV calculated from mediator-linked potentiometric titrations [15],... 

Sugiyama M, Tsuzuki K, Haramaki N. 1993. Influence of o-phenanthroline on DNA single -strand breaks, alkali-labile sites, glutathione reductase, and formation of chromium(V) in Chinese hamster V-79 cells treated with sodium chromate(VI). Arch Biochem Biophys 305(2) 261-266. 

Although the coordination chemistry of pyrimine has not been studied in any detail it is known to display many of the complexing characteristics and reactions of o-phenanthroline, dipyridyl and other compounds... 

The reagent consists of a 0-1 per cent solution of o-phenanthroline in water. 

Among several iron chelators used, only o-phenanthroline inhibited the soluble dehydrogenase (42). It was shown by Hateff et al. (42) that incubation of the enzyme with o-phenanthroline results in the loss of labile sulfide, while pretreatment with bathophenanthroline sulfonate, Tiron (1,2-dihydroxybenzene 3,5-disulfonate) or ethylenediamine tetraacetate protects the enzyme against the loss of labile sulfide and inhibition of activity upon subsequent incubation with o-phenanthroline. The unique destructive ability of o-phenanthroline has been demonstrated by these investigators for several iron-sulfur proteins (S5,96). 

D-Lactate cytochrome c reductase is inhibited by p-mercuriphenyl sulfonate salts, metal chelators, and dicarboxylic acids such as oxalate and oxaloacetate (Table XVI) (312, 314, 315). According to Nygaard (314), salts (cations) inhibit at the acceptor site, and dicarboxylic acids at the substrate site. Cremona and Singer (315) have studied the inhibitions by metal chelators and by oxalate. They recognized two types of inhibition. One type of inhibition is that which is caused by EDTA or oxalate. This kind of inhibition is reversed immediately upon dilution of the enzyme-inhibitor mixture. The second is that which results from addition of o-phenanthroline. Enzyme preparations treated with o-phenanthroline bind 2 moles of the chelator per mole of Zn . This complex is stable and inactive, and does not result in the release of Zri . The inactive... 

The ESR signal of Af, 2 could be observed in membrane preparation from a strain of Chlamydomonas reinhardii lacking PSI. The broad peak at g = 1.84 is again similar to what observed in bacterial RC and suggests a plastoquinone-Fe complex [87]. Also similar is the inhibitory effect of o-phenanthroline [88]. 

Injection of a slug of o-phenanthroline into the feed, corresponding to only 10-15% of the zeolitic aluminum in a ZSM-5 catalyst, increased sel dvity from 54% para- and 0.3% oitho-ethyltoluene to over 96% para-and no detectable ortho-isomer. Toluene (theoretical) and ethylene conversions and select vities to ethyltoluenes exceeded 90%. 

The authors proposed that chaotropic agents affect the first namely, a rate limiting migration of o-phenanthroline molecules in the protein matrix. 

There may also be specific chemical sources of discriminating interactions such as differential hydrogen bonding, as mentioned in Section 1.8 in connection with the work of Bosnich and Watts (1968). Another interesting suggestion is that of differential covalent hydration as a possible explanation of discrimination in certain complexes of o-phenanthroline [Gillard (1973, 1974)]. 

Two equivalents of an aqueous solution of o-phenanthroline are added to a solution of AgNOa. A colorless, gelatinous precipitate is formed it rapidly turns red-brown on addition of a cone, solution of (NH4)sS308. and settles on standing as fine crystals. The product is suction-filtered, washed with cold water, and dried, first with alcohol and ether and then in a desiccator. The yield is quantitative. 

Ng, S.W. Yap, C.K. Chen, W. Kumar Das, V.G. Sinn, E. Outer-sphere eoordination of o-phenanthroline in aqua-bromotri-p-tolyltin-o-phenanthroline. Main Group Met. Chem. 1997, 20. 531-534. 

THE ELECTRONIC SPECTRA, OPTICAL ROTATORY POWER, AND ABSOLUTE CONFIGURATION OF O-PHENANTHROLINE AND 2,2 -DlPYRIDYL COMPLEXES,... 

A soft donor extractant system, mixtures of o-phenanthroline and nonanoic acid. 

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