Athanor by arbastro
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How to calculate molecular weight, logP and other properties

Select the structure and choose Object › Chemistry › Calculate properties. The Compound info panel opens at Calculated, with the formula, exact mass, TPSA, donors, acceptors, rotatable bonds and the Lipinski rule-of-five checks.

On a Mac, Ctrl is Cmd.

Steps

  1. Select the structure with Select (V). The molecular weight is already in the Layers panel row and in Properties.
  2. Choose Object › Chemistry › Calculate properties, or press Ctrl+K and type calculate properties.
  3. The Compound info panel opens at Calculated.

The Calculated part of Compound info for caffeine, with its formula, exact mass and other calculated values.The Calculated part of Compound info for caffeine, with its formula, exact mass and other calculated values.

What is listed

The formula and exact mass, the topological polar surface area (TPSA), hydrogen bond donors and acceptors, rotatable bonds, and whether the structure passes Lipinski's rule of five, a quick test of how drug-like a molecule is.

These are calculated from the structure you drew, so they change as soon as you edit it.

Compound info and the LibraryThe Compound info panelSelect a structure and press I (or click the Compound info tab beside Properties). The panel says what the structure is, its other names, CAS number and PubChem record, its systematic name, its InChI and SMILES, and calculated properties.

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Last updated Nov 12, 2026