Phenanthroline

Phenanthroline

Names
IUPAC name 1,10-phenanthroline
Identifiers
CAS Number	66-71-7 Y
ChEBI	CHEBI:44975 Y
ChEMBL	ChEMBL415879 Y
ChemSpider	1278 Y
DrugBank	DB02365 Y
Jmol interactive 3D	Image
RTECS number	SF8300000
InChI InChI=1S/C12H8N2/c1-3-9-5-6-10-4-2-8-14-12(10)11(9)13-7-1/h1-8H Y Key: DGEZNRSVGBDHLK-UHFFFAOYSA-N Y InChI=1/C12H8N2/c1-3-9-5-6-10-4-2-8-14-12(10)11(9)13-7-1/h1-8H Key: DGEZNRSVGBDHLK-UHFFFAOYAW
SMILES c1cc2ccc3cccnc3c2nc1
Properties
Chemical formula	C12H8N2
Molar mass	180.21 g/mol
Appearance	colourless crystals
Density	1.31 g/cm3
Melting point	117 °C (243 °F; 390 K)
Solubility in water	moderate
Solubility in other solvents	acetone ethanol
Hazards
Main hazards	mild neurotoxin, strong nephrotoxin, and powerful diuretic
R-phrases	R25, R50/53
S-phrases	S45,S60,S61
Related compounds
Related compounds	2,2'-bipyridine ferroin phenanthrene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. It is used as a ligand in coordination chemistry, it forms strong complexes with most metal ions.^[1] In terms of its coordination properties, phen is similar to 2,2'-bipyridine (bipy).

Synthesis

Phenanthroline may be prepared by two successive Skraup reactions of glycerol with o-phenylenediamine, catalyzed by sulfuric acid, and an oxidizing agent, traditionally aqueous arsenic acid or nitrobenzene.^[2] Dehydration of glycerol gives acrolein which condenses with the amine followed by a cyclization.

Peptidase inhibitor

1,10-Phenanthroline is an inhibitor of metallopeptidases, with one of the first observed instances reported in carboxypeptidase A.^[3] Inhibition of the enzyme occurs by removal and chelation of the metal ion required for catalytic activity, leaving an inactive apoenzyme. 1,10-Phenanthroline targets mainly zinc metallopeptidases, with a much lower affinity for calcium.^[4]

Ferroin and analogues

The complex [Fe(phen)₃]²⁺, called "ferroin," is used for the photometric determination of Fe(II).^[5] It is used as a redox indicator with standard potential +1.06 V. The reduced ferrous form has a deep red colour and the oxidised form is light-blue.^[6] Ferroin is used as a cell permeable inhibitor for metalloproteases in cell biology.

The pink complex [Ni(phen)₃]²⁺ has been resolved into its Δ and Λ isomers.^[7] The analogous [Ru(phen)₃]²⁺ has long been known to be bioactive.^[8]

Related phen ligands

A variety of substituted derivatives of phen have been examined as ligands. Neocuproine, 2,9-dimethyl-1,10-phenanthroline, is a bulky ligand. In "bathophenanthroline," the 4 and 7 positions are substituted by phenyl groups. The more electron-rich phenanthroline ligand is 3,4,7,8-tetramethyl-1,10-phenanthroline.^[1]

Numbering for 1,10-phenanthroline derivatives.

As an indicator for alkyllithium reagents

Alkyllithium reagents form deeply colored derivatives with phenanthroline. The alkyllithium content of solutions can be determined by treatment of such reagents with small amounts of phenanthroline (ca. 1 mg) followed by titration with alcohols to a colourless endpoint.^[9]

Grignard reagents may be similarly titrated.^[10]

References

1. 1 2 C.R. Luman, F.N. Castellano "Phenanthroline Ligands" in Comprehensive Coordination Chemistry II, 2003, Elsevier. ISBN 978-0-08-043748-4.
2. ↑ B. E. Halcrow, W. O. Kermack (1946). "43. Attempts to find new antimalarials. Part XXIV. Derivatives of o-phenanthroline (7 : 8 : 3′ : 2′-pyridoquinoline)". J. Chem. Soc.: 155–157. doi:10.1039/jr9460000155. 
3. ↑ Felber, JP, Coombs, TL & Vallee, BL (1962). "The mechanism of inhibition of carboxypeptidase A by 1,10-phenanthroline". Biochemistry 1 (2): 231–238. doi:10.1021/bi00908a006. PMID 13892106. 
4. ↑ Salvesen, GS & Nagase, H (2001). "Inhibition of proteolytic enzymes". Proteolytic enzymes: a practical approach, 2 edn 1: 105–130. 
5. ↑ Belcher, R. "Application of chelate Compounds in Analytical Chemistry" Pure and Applied Chemistry, 1973, volume 34, pages 13-27.
6. ↑ Bellér, G. �B.; Lente, G. �B.; Fábián, I. �N. (2010). "Central Role of Phenanthroline Mono-N-oxide in the Decomposition Reactions of Tris(1,10-phenanthroline)iron(II) and -iron(III) Complexes". Inorganic Chemistry 49 (9): 3968–3970. doi:10.1021/ic902554b. PMID 20415494.  replacement character in |first2= at position 4 (help); replacement character in |first1= at position 4 (help); replacement character in |first3= at position 4 (help)
7. ↑ George B. Kauffman, Lloyd T. Takahashi (1966). "Resolution of the tris-(1,10-Phenanthroline)Nickel(II) Ion". Inorg. Synth. 5: 227–232. doi:10.1002/9780470132395.ch60. 
8. ↑ F. P. Dwyer, E. C. Gyarfas, W. P. Rogers, J. H. Koch (1952). "Biological Activity of Complex Ions". Nature 170 (4318): 190–191. doi:10.1038/170190a0. PMID 12982853. 
9. ↑ Paul J. Fagan and William A. Nugent (1998). "1-Phenyl-2,3,4,5-Tetramethylphosphole". Org. Synth. ; Coll. Vol. 9, p. 653 
10. ↑ Ho-Shen Lin, Leo A. Paquette (1994). "A Convenient Method for Determining the Concentration of Grignard Reagents". Synth. Commun. 24 (17): 2503–2506. doi:10.1080/00397919408010560.