1,10-Phenanthroline, a widely employed chelate in supramolecular chemistry,108 develops a complicated with p-sulfonatocalix<4>arene as a face-to-face dimer, wherein each the the π⋯π stack 1,10-phenanthroline molecules room bound slantwise in a calixarene cavity as part that a molecule capsule (Fig. 22A and also B). These are assembled right into columns or tapes in the prolonged 3D structure.109,110 various other variation that binding settings for the two contents include the formation of an open inclusion complicated rather than creating a capsule in the visibility of the hexa-aqua aluminum ion.111 for the open up inclusion complex, the overall plan is a chain-like motif with the had 1,10-phenanthroline cations π-stacked through exo walls of surrounding calixarenes. A comparable structure was developed with 5,6-dihydropyrazion<1,2,3,4-lmn><1,10>-phenanthroline-4,7-diium (Fig. 22C and also D).112 1H NMR data is continual with the plan of the heavy state crystal structures.109,110



Figure 22. Molecule capsule containing two molecules that π-stacked 1,10-phenanthroline (A) and matching extended framework (B). Inclusion facility of 5,6-dihydropyrazion<1,2,3,4-lmn><1,10>-phenanthroline-4,7-diium (C), and also corresponding prolonged structure (D).109,110 H atoms omitted because that clarity.

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Copper(II) or lanthanide(III) ion (Gd3 +, Tb3 +, Nd3 +, Ce3 +) in a mixture that 1,10-phenanthroline and also p-sulfonatocalix<4>arene result in assemblies in i beg your pardon a steel chelate complicated is also coordinated come the calix<4>arene with a sulfonate team (Fig. 23).117–120 Interestingly, the 2:2 bis-molecular capsule confining 2 1,10-phenanthroline molecules persists together with metal coordination near the capsule seam. For the Cu2 + complex, the capsules are arranged v water networks present in the prolonged structure, while because that the Ln3 + complexes, the overall structure has wave-like great of chains and also grid-like chains.117–119 A 1:1 inclusion complex of 1,10-phenanthroline and calix<4>arene additionally forms for Zn2 + coordinated to 1,10-phenanthroline in an as whole bilayer arrangement.121



Figure 23. Variation in host–guest interactions and also the in its entirety self-assembly because that 1,10-phenanthroline coordinated by transition-metal (Cu2 +) and also lanthanides (Gd3 +, Nd3 +).113–116 H atoms omitted because that clarity.


Other supramolecular arrangements based upon 1,10-phenanthroline and also p-sulfonatocalix<4>arene incorporate coordination that the calixarene in between two binuclear oxo-bridged Fe3 + phenanthroline complexes (Fig. 24A).122 In another finding, a tris-1,10-phenanthroline Ni2 + facility is formed and one of this ligands inserts right into the calixarene cavity as displayed in Fig. 24B.



Figure 24. (A) Ball and stick representation of p-sulfonatocalix<4>arene molecules in between two dinuclear oxo-bridged iron(III) phenanthroline complexes. (B) Tris(1,10-phenanthroline) Ni(II) complicated partially consisted of in the calixarene cavity.122 H atoms omitted because that clarity.


Binding that Nd3 + and Eu3 + by 2 1,10-phenanthroline molecule in the existence of p-sulfonatocalix<4>arene outcomes in 3D metal-organic-frameworks (Fig. 25).119 each calix<4>arene is rotated by 90 degrees, providing rise come parallel packing in a tetrameric cyclic array. The coordination ball of every octa-coordinate lanthanide facility is perfect by oxygen atoms from 4 calixarene sulfonato groups. Every calixarene connects four different lanthanide centers in the extended structure.



Figure 25. Three-dimensional lanthanide/p-sulfonatocalix<4>arene/1,10-phenanthroline metal-organic-framework.119 H atom omitted because that clarity.


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Separation, Preconcentration and also Spectrophotometry in inorganic Analysis


Zygmunt Marczenko, Maria Balcerzak, in analytical Spectroscopy Library, 2000

26.2.2.1,10-Phenanthroline method

1,10-Phenanthroline (phen, formula 26.1 ) and also 2,2'-bipyridyl (formula 26.2) room organic bases v very comparable chemical properties.


(26.1)
(26.2)

Both reagents react quickly with Fe2 + ions in weakly acid media to provide orange-red or pink complexes, respectively, which space a basis for determining Fe(II) <27,28>. The absorption spectra that both complexes are presented in Fig. 26.1.



Fig. 26.1. Absorption spectra that the iron complexes: iron(II) – 1,10-phenanthroline (1), iron(III) – 1,10-phenanthroline (2), and iron(II) – 2,2'-bipyridyl (3).


The molar absorptivity of the Fe(II) facility with 1,10-phenanthroline is 1.10 · 104 (a = 0.20) in ~ λmax 512 nm, and also that that the facility with 2,2'-bipyridyl is 8.7-103 in ~ λmax 522 nm. Remedies of the complexes v phenanthroline and also bipyridyl are stable, and also the Fe(II) bound in the facility is resistant come oxidation.

Iron(II) and total iron can be figured out with phenanthroline or bipyridyl after reduction of Fe(in) come Fe(II). Hydroxylamine reduces Fe(III) within a few minutes in a weakly acidic tool (pH 3–4): ascorbic mountain is a better reductant in a fairly acidic systems (pH 0–1). Other reducing agents supplied are sulphite, dithionite, and also hypophosphite <28>.

The colour reactions are usually brought out in acetate or citrate buffers. The visibility of citrate or tartrate is preferable as it stays clear of the precipitation of certain cations which hydrolyse in weak acid media (e.g., Ti, Al, and Bi). In the determination of Fe(II) with phenanthroline, Fe(III) have the right to be masked v NTA <29> or fluoride <30>.

The complicated of 1,10-phenanthroline with Fe(II) is referred to as ferroin and has been widely used in titrimetric analysis as a redox indicator .

1,10-Phenanthroline develops with Fe(III) a blue complicated (λmax 585 nm) which has been provided for identify larger amounts of iron.

Phenanthroline and also 2,2'-bipyridyl kind complexes, back not intensely coloured, v Ru, Os, and Cu(I). Countless metals (e.g., Zn and also Cd) can type colourless complexes through phenanthroline and bipyridyl, which are an ext stable than the equivalent Fe(II) complexes. When determining Fe in the existence of Zn or Cd, EDTA should be supplied as a masking certified dealer <31>. Copper have the right to be masked with triethylenetetramine <32>.

Fe(II)– complexes v phenanthroline and 2,2'-bipyridyl form extractable ion-associates, e.g.,with nitroprusside <33>, tetraphenylborate <34>, or picrate <35>. Fe has been figured out by derivative spectrophotometry, after extraction of the ferroin associate v perchlorate anion <36>.

The 1,10-phenanthroline an approach has been offered in the automatically FIA an approach <37–40>.

Reagents

1,10-Phenanthroline (phen), 0.2% systems of the hydrochloride or hydrate in -0.1 MHC1. Traditional iron solution: 1 mg/ml. Preparation as in Section 26.2.1. Hydroxylamine hydrochloride, 10% solution, fresh prepared.

Procedure

To a slightly acid solution, containing not an ext than 80 μg the Fe(III) or Fe(II), add 1 ml of the NH2OH solution and also 10% sodium citrate solution, it spins the pH is 3-4. Transfer the equipment to a 25-ml conventional flask, add 3 ml that the phen solution, dilute to the note with water, and mix thoroughly. After 5 min, measure the absorbance the the solution at 512 nm against water.


Procedure.

Accurately weigh around 10 mg that the finely powdered silicate material right into a dried polyethylene bottle and a similar amount that the referral sample into a 2nd bottle. Use a third bottle for the reference blank solution. Include approximately 20 mg of the 1,10-phenanthroline come each followed by 3 ml the 4 N sulphuric acid and 0.5 ml of concentrated hydrofluoric acid. Transport the bottles to a vapor bath in a solved order, so the the an initial one on will certainly be the an initial off, and also leave because that 30 minutes.

While the bottles are on the vapor bath, transfer 5 ml the the boric acid solution to every of a series of 100-ml volumetric flasks. Utilizing the very same order together previously, remove the party from the heavy steam bath and, as swiftly as possible, add 20 ml of sodium citrate equipment to each bottle. As far as feasible each bottle should be left on the steam bath because that the same length of time. Transport the contents of each bottle to among the 100-ml volumetric flasks, using water to rinse the bottles. Cool come room temperature, dilute each solution to volume with water and also mix well.

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Using a spectrophotometer collection at wavelengths of 555 nm and also 640 nm, measure the optical densities the the options using the empty as the reference solution. For each solution, subtract the optical density at 640 nm native that acquired at 555 nm, and determine the ferrous iron contents of the sample by reference to the optical density difference acquired for the silicate rock of recognized ferrous steel content.