These data were compiled and described by Burns et al. (2004). The data set consists of 80 compounds that were designated as either crossing the blood-brain barrier or not crossing. The structures and outcomes were obtained from http://www.qsarworld.com/index.php.The package contains none sets of molecular descriptors: atom pair distances, Daylight fingerprints (http://www.daylight.com/dayhtml/doc/theory/theory.finger.html), Dragon descriptors (http://www.talete.mi.it/products/dragon_plus.htm), MOE2D, MOE2D fingerprints, MOE3D, PipelinePilot fingerprints (http://accelrys.com/products/pipeline-pilot/) and QuickProp descriptors.
For fingerprints, the 500 most variable bits were selected whenever possible.
There are compounds with missing data for some descriptors.
The "2" in the name is due to another data set in the caret package for blood-brain barrier data (with numeric outcomes). These are a completely different set of compounds and have no connection.