Indigo
Athanor · official
C16H10N2O2 · 262.26 g/mol
IUPAC name: 2-(2-hydroxy-1H-indol-3-yl)indol-3-one
Also called indigotin, denim dye
WarningCauses skin irritation · Causes serious eye irritation · May cause respiratory irritationNames and identifiers
- IUPAC name
- 2-(2-hydroxy-1H-indol-3-yl)indol-3-one
- Synonyms
- indigotin, denim dye, 2H-Indol-2-one, 3-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,3-dihydro-
+ 36 more
RefChem:484285, 2H-Indol-2-one, 3-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,3-dihydro-(9CI), 610-392-0, Indirubin, Indigopurpurin, Couroupitine B, Indigo Red, (Z)-[2,3'-biindolinylidene]-2',3-dione, [2,3'-Biindolinylidene]-2',3-dione, Isoindirubin, (E)-[2,3'-biindolinylidene]-2',3-dione, Isoindirubine, Isoindogotin, Indirubin [MI], MFCD00956441, NSC-105327, 2H-Indol-2-one,3-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,3-dihydro-, 2-(2-hydroxy-1H-indol-3-yl)indol-3-one, (Z)-Indirubin, Z-Indirubin-D8, NSC 105327, INDARUBICIN, 3-(1,3-dihydro-3-oxo-2h-indol-2-ylidene)-1,3-dihydro-2h-indol-2-one, C.I. 73200, (3Z)-3-(1,3-Dihydro-3-oxo-2H-indol-2-ylidene)-1,3-dihydro-2H-indol-2-one, MFCD00221745, (3Z)-3-(3-oxoindolin-2-ylidene)indolin-2-one, Indirubin 3E-form [MI], 1LXW6D3W2Z, KBioGR_000450, V86L8P74GI, C.I. 75790, HMS2234G06, AKOS032455876, DB12379, 3-(3-oxoindolin-2-ylidene)indolin-2-one
- Molecular formula
- C16H10N2O2
- Empirical formula
- C8H5NO
- Molecular weight
- 262.26 g/mol
- Exact mass
- 262.07423
- CAS number
- 482-89-3
- PubChem CID
- 10177
- Canonical SMILES
- C1=CC=C2C(=C1)C(=C(N2)O)C3=NC4=CC=CC=C4C3=O
- Isomeric SMILES
- C1=CC=C2C(=C1)C(=C(N2)O)C3=NC4=CC=CC=C4C3=O
- InChI
- InChI=1S/C16H10N2O2/c19-15-10-6-2-4-8-12(10)17-14(15)13-9-5-1-3-7-11(9)18-16(13)20/h1-8,18,20H
- InChIKey
- JNLNPCNGMHKCKO-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Calculated
- Heavy atoms
- 20
- Rings
- 4
- Aromatic rings
- 2
- Fraction sp³ carbons (Fsp3)
- 0
- H-bond donors
- 2
- H-bond acceptors
- 3
- Rotatable bonds
- 0 computed here · PubChem 1
- TPSA (Ų)
- 58.2 computed here · PubChem 65.5
- Formal charge
- 0
- XLogP3
- 2.7 PubChem
- Complexity
- 448 PubChem
- Stereocenters
- None
- Double-bond geometry
- C10=C11: E
- Point group
- C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)
Elemental analysis
- C73.27%
- H3.84%
- N10.68%
- O12.20%
Isotope pattern
Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.
Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.
Predicted
- log P
- 2.66 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -3.58 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 2.28 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 262.27
- log P ≤ 5 (Crippen): 2.66
- H-bond donors ≤ 5: 2
- H-bond acceptors ≤ 10: 3
Passes all four rules.
¹³C NMR shifts, predicted
Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.
Safety
Warning
From European Chemicals Agency (ECHA). Source [1].
- Harmful or irritant
- H315Causes skin irritation
- H319Causes serious eye irritation
- H335May cause respiratory irritation
Precautionary statements: P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Safety data sheets on the supplier’s page: Accel Scientific, Sigma-Aldrich, BLD Pharm.
Always read the supplier’s safety data sheet before working with it.
Spectra
- LC-MSMassBank of North America (MoNA) (Thermo Q Exactive HF · LC-ESI-QFT · negative) · MassBank of North America (MoNA) (SCIEX TripleTOF 6600 · LC-ESI-QTOF · positive) · MassBank of North America (MoNA) (SCIEX TripleTOF 6600 · LC-ESI-QTOF · negative) · MassBank of North America (MoNA) (Orbitrap · positive)
- Other MSMassBank of North America (MoNA) (ESI-Orbitrap · positive) · MassBank of North America (MoNA) (ESI-Orbitrap · positive) · MassBank of North America (MoNA) (ESI-Orbitrap · positive)
Experimental spectra held by these sources; each link opens the source's own record.
Literature
Reading PubChem, OpenAlex and GSRS…
Bioactivity
Reading ChEMBL…
References
- [1]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [2]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
- ·Literature on PubChem
Data last updated 2026-10-14.