Structure and reactivity of monolayer and micelle interfaces

The research in this thesis is focused on the structure and reactivity of monolayer and micelle interfaces.The kinetic results of ring formations of a series of $ sigma$-($ omega$-bromoalkoxy)phenoxides in a cationic micellar environment (CTAB) revealed that the ring closure rate constants from the 7-membered ring to the 14-membered ring decrease by $ sim$6-fold. This is much smaller than that observed for a homogeneous reaction environment ($ sim$1500-fold). In addition, micellar effective molarities (EM)$ sb{ rm m}$ for these reactions are found to be 7 to 1900 fold greater than in homogeneous solution. This catatysis can be reasoned to originate from an increase in the ground-state free energy of the substrate induced by localization of the phenolate oxygen and alkyl bromide moieties at the polar micelle interface.Monolayer isotherm studies establish a dependence of isotherm features on the structure of the phospholipid. It is found that the liftoff area increases as the position of the second hydrophilic group is located further from the dominate polar group. The transition pressure reaches its highest value when the substituent is in the 7-position. The condensed area for almost all these substrates gives nearly the same value ($ sim$45 A$ sp2$/molecule). These may be explained by that the molecules lie flatly on the air/water interface at high surface concentration after which the hydrophobic parts in a molecule are forced out of the water surface. The hydrophilic groups remain on the water surphase so as to produce a loop conformation. At high pressure all the molecules are approximately perpendicular to the water surface so as to form a highly dense packing state. The unusually broad first order phase transition in isotherms of some boloform and macrocyclic phospholipids is consistent with these substrates being reorientated at large areas to yield stable bilayers, trilayers, etc