ClogP and CMR
PCModels is a Daylight software module providing access to two chemical models: CLOGP (hydrophobicity partition coefficient) and CMR (molar refractivity). These models are developed and supported by BioByte, Inc. of Claremont, CA. Daylight has worked with BioByte to offer PCModels in its current form: a convenient user-interface compatible with Daylight's other software.
Since its ground-breaking inception in the early 80's, ClogP has set the 'gold standard' for the precision of its logP octanol/water estimates, but users have often been troubled by the 'missing fragment' messages that arise for fragments not yet measured. However, with the release of ClogP 4.0, all fragment values can now be estimated. Just as important, ClogP also estimates interaction parameters for these new fragments. ClogP bases its estimation of these interactions on the well-accepted principles defined by Hammett and are based on established chemical interactions, not statistics.