Neocuproine

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Neocuproine
Neocuproine.jpg
Neocuproin.svg
Names
Preferred IUPAC name
2,9-Dimethyl-1,10-phenanthroline
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.006.911 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 207-601-9
PubChem CID
UNII
  • InChI=1S/C14H12N2/c1-9-3-5-11-7-8-12-6-4-10(2)16-14(12)13(11)15-9/h3-8H,1-2H3 X mark.svgN
    Key: IYRGXJIJGHOCFS-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C14H12N2/c1-9-3-5-11-7-8-12-6-4-10(2)16-14(12)13(11)15-9/h3-8H,1-2H3
    Key: IYRGXJIJGHOCFS-UHFFFAOYAL
  • n1c3c(ccc1C)ccc2ccc(nc23)C
Properties
C14H12N2
Molar mass 208.264 g·mol−1
AppearancePale yellow solid
Melting point 162 to 164 °C (324 to 327 °F; 435 to 437 K)
Slightly soluble
Solubility Ethanol, Acetone, Ether, Benzene, Light Petroleum (slightly) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Neocuproine is a heterocyclic organic compound and chelating agent. Phenanthroline ligands were first published in the late 19th century, and the derivatives substituted at the 2 and 9 positions are among the most studied of the modified phenanthrolines. [2] [3]

Contents

Synthesis and structure

Neocuproine can be prepared by sequential Skraup reactions (Doebner-Miller reaction/condensation) of o-nitroaniline (2-Nitroaniline) with crotonaldehyde diacetate. An alternate synthesis involves the condensation of o-phenylenediamine, m-nitrobenzenesulphonate, and crotonaldehyde diacetate. This method gives higher yields but is less economical. [1] Neocuproine crystallizes as a dihydrate and a hemihydrate.

structure of [NiCl2(neocuproine)]2. NIPHOJ.png
structure of [NiCl2(neocuproine)]2.

Coordination chemistry

In the early 1930s, phenanthroline derivatives became known for their use as colorimetric indicators for many transition metals. Neocuproine proved to be highly selective for copper(I). The resulting complex, [Cu(neocuproine)2]+ has a deep orange-red color. [1] The properties of copper(I) neocuproine complexes have been widely studied, e.g. for the preparation of catenane and rotaxane complexes. [4] The copper-catalyzed release of NO+ (nitrosonium) from S-Nitrosothiols is inhibited by neocuproine. [5]

Relative to 1,10-phenanthroline, neocuproine bears steric bulk flanking the nitrogen donor sites. A major consequence is that complexes of the type [M(neocuproine)3]n+ are disfavored, in contrast to the situation with phenanthroline ligands that lack substitution in the 2,9 positions. [6] The ligand bathocuproine is similar to neocuproine, but has phenyl substituents at the 4,7-positions.

Other metals

Platinum forms the square planar complexes [PtX2(2,9-dimethyl-1,10-phenanthroline)]. [7]

Neocuproine has also been discovered to have properties that cause fragmentation and disappearance of the melanin in adult zebrafish melanocytes. Those expressing eGFP also have been observed to lose eGFP fluorescence in the presence of neocuproine. [8]

Related Research Articles

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Copper(II) nitrate describes any member of the family of inorganic compounds with the formula Cu(NO3)2(H2O)x. The hydrates are blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at 150-200 °C. Common hydrates are the hemipentahydrate and trihydrate.

<span class="mw-page-title-main">Terpyridine</span> Chemical compound

Terpyridine is a heterocyclic compound derived from pyridine. It is a white solid that is soluble in most organic solvents. The compound is mainly used as a ligand in coordination chemistry.

<span class="mw-page-title-main">1,10-Phenanthroline</span> Heterocyclic organic compound

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.

The Ullmann condensation or Ullmann-type reaction is the copper-promoted conversion of aryl halides to aryl ethers, aryl thioethers, aryl nitriles, and aryl amines. These reactions are examples of cross-coupling reactions.

<span class="mw-page-title-main">Metal ammine complex</span>

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<i>o</i>-Phenylenediamine Chemical compound

o-Phenylenediamine (OPD) is an organic compound with the formula C6H4(NH2)2. This aromatic diamine is an important precursor to many heterocyclic compounds. It is isomeric with m-phenylenediamine and p-phenylenediamine.

<span class="mw-page-title-main">Trispyrazolylborate</span>

The trispyrazolylborate ligand, abbreviated Tp, is an anionic tridentate and tripodal ligand. Trispyrazolylborate refers specifically to the anion [HB(C3N2H3)3], but the term trispyrazolylborate refers to derivatives substituted at on the pyrazolyl rings. This family of compounds are sometimes called scorpionate ligands.

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3
COCHCOCH
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5
H
7
O
2
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References

  1. 1 2 3 O'Reilly, E. J.; Plowman, R. A. (1959). "Coordination Compounds of Substituted 1,10-Phenanthrolines and Related Dipyridyls". Australian Journal of Chemistry. 13 (1): 145–149. doi:10.1071/CH9600145.
  2. M. K. Eggleston; P. E. Fanwick; A. J. Pallenberg; D. R. McMillin (1997). "A Twist on the Copper Center in the Crystal Structure of [Cu(dnpp)2]PF6 and the Charge-Transfer Excited State? (dnpp = 2,9-Dineopentyl-1,10-phenanthroline)". Inorganic Chemistry. 36 (18): 4007–4010. doi:10.1021/ic970135e.
  3. Chandler, Christopher J.; Deady, Leslie W.; Reiss, James A. (1981). "Synthesis of some 2,9-Disubstituted-1,10-phenanthrolines". Journal of Heterocyclic Chemistry. 18 (3): 599–601. doi:10.1002/jhet.5570180332.
  4. McCleverty, J; Meyer, T. J. "Phenanthroline Ligands" in Comprehensive Coordination Chemistry II, Vol. 1, 2004, p.25-39.
  5. Al-Sa’doni, H.H.; Megson, I.L.; Bisland, S.; Butler, A.R.; Flitney, F.W. Neocuproine, A Selective Cu(I) Chelator, and the relaxation of rat vascular smooth muscle by S-nitrosothiols. British Journal of Pharmacology , 121(6), 1997, p.1047-1050. doi : 10.1038/sj.bjp.0701218
  6. Pallenberg, A. J.; Marschner, T. M.; Barnhart, D. M. (1997). "Phenanthroline complexes of the d10 Metals Nickel(0), Zinc(II) and Silver(I)—Comparison to Copper(I) Species". Polyhedron. 16 (16): 2711–2719. doi:10.1016/S0277-5387(97)00051-X.
  7. Fanizzi, Francesco P.; Margiotta, Nicola; Lanfranchi, Maurizio; Tiripicchio, Antonio; Pacchioni, Gianfranco; Natile, Giovanni "A Molecular Tool for Measuring the Electron-Acceptor Ability of Ligands from Crystallographic Data" European Journal of Inorganic Chemistry volume 8, 2004, p.1705-1713. doi : 10.1002/ejic.200300888
  8. O’Reilly-Pol, Thomas; Johnson, Stephen L. "Neocuproine Ablates Melanocytes in Adult Zebrafish" Zebrafish 5(4). Mary Ann Liebert, Inc. 2008. doi : 10.1089/zeb.2008.0540

Appendix: NMR Shifts

The following figures contain information on the nuclear magnetic resonance spectroscopic data of neocuproine (from Chandler et al.):

1H NMR
SubstituentChemical Shift (δ ppm)
H-3,87.45
H-4,78.03
H-5,67.65
1H Decoupled 13C NMR
SubstituentChemical Shift (δ ppm)
C-2159.2
C-10b145.1
C-4136.2
C-4a126.7