Experimental determination of octanol-water partition coefficient (KOW) of 39 liquid crystal monomers (LCMs) by use of the shake-flask method

Liquid crystal monomers (LCMs) were recently proposed as persistent, bioaccumulative, and toxic substances; however, there is a dearth of information regarding their experimental octanol-water partition coefficients (KOW). In the present study, we determined the experimental KOW values of these 39 LCMs by use of a classic shake-flask method. We observed that experimental KOW values of LCMs largely varied depending on their specific structures, and the Log transformed KOW generally fall in the range of 4.94-7.62. The experimental KOW values were further compared with those predicted by Estimation Programs Interface (EPI) Suite software. Interestingly, we observed that experimental and estimated Log KOW values were generally comparable for LCMs containing two benzene or cyclohexane rings; however, the estimated values gradually deviated from the experimental ones as the number of benzene or cyclohexane rings of LCM structures increased. Based on the experimental Log KOW values of 39 LCMs, we established a quantitative structure activity relationship (QSAR) model for predicting Log KOW values of other LCMs, for which authentic standards are not available. Adjusted square of determination coefficient (R2) of the developed model is 0.810, indicating its goodness-of-fit for estimation of Log KOW values of other substances with similar backbone structures. Overall, our present study provides the first insight on experimental Log KOW values of LCMs, and suggests that LCMs are inclined to accumulative in the fatty tissue of organisms in the aqueous environments.