1,10-Phenanthroline

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Phenanthroline
1,10-phenanthroline
Sample of 1,10-Phenanthroline
Names
Preferred IUPAC name
1,10-Phenanthroline[1]
Identifiers
3D model (
JSmol
)
126461
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
100.000.572 Edit this at Wikidata
EC Number
  • 200-629-2
  • monohydrate: 627-114-9
4040
KEGG
RTECS number
  • SF8300000
UNII
UN number 2811
  • InChI=1S/C12H8N2/c1-3-9-5-6-10-4-2-8-14-12(10)11(9)13-7-1/h1-8H checkY
    Key: DGEZNRSVGBDHLK-UHFFFAOYSA-N checkY
  • 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
  • c1cc2ccc3cccnc3c2nc1
  • monohydrate: C1=CC2=C(C3=C(C=CC=N3)C=C2)N=C1.O
Properties
C12H8N2
Molar mass 180.21 g/mol
Appearance colourless crystals
Density 1.31 g/cm3
Melting point 118.56 °C (245.41 °F; 391.71 K)[2]
Boiling point 409.2[2]
high[2]
Solubility in other solvents acetone, ethanol[2]
Acidity (pKa) 4.84 (phenH+)[2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
mild neurotoxin, strong nephrotoxin, and powerful diuretic
GHS labelling:
GHS06: ToxicGHS09: Environmental hazard
Danger
H301, H410
P264, P270, P273, P301+P310, P321, P330, P391, P405, P501
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).
checkY verify (what is checkY☒N ?)

1,10-Phenanthroline (phen) is a

heterocyclic organic compound. It is a white solid that is soluble in organic solvents. The 1,10 refer to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene
.

Abbreviated "phen", it is used as a

coordination chemistry, forming strong complexes with most metal ions.[3][4]
It is often sold as the monohydrate.

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.[5] Dehydration of glycerol gives acrolein which condenses with the amine followed by a cyclization.

Coordination chemistry

In terms of its coordination properties, phenanthroline is similar to

2,2'-bipyridine (bipy) with the advantage that the two nitrogen donors are preorganized for chelation. Phenanthroline is a stronger base than bipy. According to one ligand ranking scale, phen is a weaker donor than bipy.[6]

Several homoleptic complexes are known of the type [M(phen)3]2+. Particularly well studied is [Fe(phen)3]2+, called "

standard potential +1.06 V. The reduced ferrous form has a deep red colour and the oxidised form is light-blue.[8] The pink complex [Ni(phen)3]2+ has been resolved into its Δ and Λ isomers.[9] The complex [Ru(phen)3]2+ is bioactive.[10]

Copper(I) forms [Cu(phen)2]+, which is luminescent.[11][12]

Bioinorganic chemistry

1,10-Phenanthroline is an

metallopeptidases, with one of the first observed instances reported in carboxypeptidase A.[13] 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.[14]

Related phen ligands

A variety of substituted derivatives of phen have been examined as ligands.[12][15] Substituents at the 2,9 positions confer protection for the attached metal, inhibiting the binding of multiple equivalents of the phenanthroline. Such bulky ligands also favor trigonal or tetrahedral coordination at the metal.[16] Phen itself form complexes of the type [M(phen)3]Cl2 when treated with metal dihalides (M = Fe, Co, Ni). By contrast, neocuproine and bathocuproine form 1:1 complexes such as [Ni(neocuproine)Cl2]2.[17]

Basicities of 1,10-Phenanthrolines and 2,2'-Bipyridine[18]
phen derivative pKa comment/alt. name numbering scheme
1,10-phenanthroline 4.86 phen Numbering for 1,10-phenanthroline derivatives.
2,2'-bipyridine
4.30 bipy
5-nitro-1,10-phenanthroline 3.57
2,9-dimethyl-1,10-phenanthroline unknown neocuproine[19][20]
2,9-Dimethyl-4,7-diphenylphenanthroline unknown Bathocuproine[19][21]
4,7-dimethyl-1,10-phenanthroline 5.97
4,7-diphenyl-1,10-phenanthroline unknown bathophenanthroline[22]
5,6-dimethyl-1,10-phenanthroline 5.20 5,6-Me2phen
3,4,7,8-tetramethylphenanthroline 6.31 3,4,7,8-Me4phen[23]
4,7-dimethoxy-1,10-phenanthroline 6.45 4,7-(MeO)2phen[24]
2,6-dimesitylphenanthroline unknown HETPHEN[25][16]

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

Grignard reagents may be similarly titrated.[27]

See also

  • Ferroin – Complex of Fe2+ by ortho-phenanthroline

References