IR Spectrum Simulator Simulate infrared spectra directly from your molecular structure
Demo version — learn how the tool works before registering.
What is the IR Spectrum Simulator?
The IR Spectrum Simulator predicts the infrared absorption spectrum of any organic molecule directly from its structural formula. You draw or import a molecule and the tool returns a simulated transmittance spectrum, with each absorption band labelled by the bond responsible for it.
The predictions are based on a bond-environment database built from thousands of high-precision quantum chemistry calculations (gas-phase DFT). Each bond in your molecule is matched to the closest entry in the database using graph-isomorphism on the local chemical environment, and the corresponding frequency and intensity are retrieved.
The result is an interactive Plotly chart showing wavenumber (cm⁻¹) on the x-axis and transmittance (a.u.) on the y-axis, with annotations identifying the contributing bonds.
Why Use the IR Spectrum Simulator?
- Structure verification: confirm that a synthesised compound contains the expected functional groups before running expensive analytical experiments.
- Teaching aid: understand which bonds absorb at which frequencies and how the chemical environment influences band position and intensity.
- Spectral assignment: match observed absorption bands to specific bonds in a proposed structure, accelerating the identification process.
- Comparison with experimental data: overlay simulated and measured spectra to quickly spot discrepancies that hint at structural errors.
Unlike black-box machine-learning tools, MID's predictions remain interpretable — every band is traceable back to a specific bond in your structure.
General Example — Ethanol
Consider ethanol (CH₃CH₂OH). The simulator predicts the following characteristic absorptions:
- ~3300–3500 cm⁻¹ — broad O–H stretch (hydrogen-bonded hydroxyl)
- ~2900–3000 cm⁻¹ — C–H stretches (methyl and methylene)
- ~1450 cm⁻¹ — C–H bending (CH₂ and CH₃)
- ~1050–1100 cm⁻¹ — C–O stretch
Each band in the simulated spectrum is annotated with the atom numbers of the bond that causes it, so you can immediately relate a spectral feature back to a specific part of your structure. This makes the tool particularly useful for structure elucidation when you have multiple candidate molecules.
Register for free to run predictions on your own molecules.