Download of MoleculeSketch 2.8 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The program belongs to Education Tools. We recommend checking the downloaded files with any free antivirus. The actual developer of this Mac application is Stefan Dolder.
From the developer:
MoleculeSketch is a simple and easy-to-use molecule drawing tool for Mac OSX. Atoms and bonds are nicely positioned by locking. The types of bonds can be changed by clicking on existing bonds. Different atom and bond attributes (like missing hydrogen atoms), non-bonding electron pairs on hetero-atoms, font size and type, bond line width or color can be accessed and changed through pop-over panels.
You may want to check out more Mac applications, such as LabAssistant, Schematics Plus or Gnaural, which might be similar to MoleculeSketch.