The effect of anaesthetic-like molecules on the phase transition in smectic mesophases of dipalmitoyllecithin I. The normal alcohol up to C = 9 and three inhalation anaesthetics

The effect of the normal alcohols (up to $\text{C = 9}$) and three clinically used anaesthetics, on the crystalline-liquid crystalline phase transition in $\text{1,2-}\text{dihexadecyl}\text{-sn-}\text{glycero}\text{-3-}\text{phosphorylcholine}$ have been studied. A one-degree depression was produced by a 4.4% concentration in the membrane of $\text{n-}\text{octanol}$ and $\text{n-}\text{nonanol}$ agreeing well with the value calculated from the temperature and enthalpy of the transition. It is also shown that the relationship between the partition coefficient $\text{P}$ and the water solubility $\text{S (P · S = 2)}$, holds for the solutes investigated here. The experimental method described offers a simple way of assessing the anaesthetic potency of a wide range of compounds.