Gas-surface interactions with Langmuir-Blodgett films of new derivatives of dibenzo-tetra-aza-dihydro-(14)-annulene

Abstract

The authors new derivatives of the parent macrocyclic ligand dibenzo-(b,i)(1,4,8,11)tetra-aza-(4,11)dihydro-(14)-annulene (TTA) can be divided into two classes on the basis of their behaviour concerning the formation of (floating) Langmuir monolayers and solid-supported Langmuir-Blodgett (LB) monolayers and multilayers. Class I consists of molecules that are highly hydrophobic but do not contain a formal hydrophilic centre whereas the class II molecules are truly amphiphilic. The class I compounds all formed stable Langmuir monolayers at surface pressures of 10-15 mN m-1 for prolonged periods and, for the C(6) and C(14) compounds, similar stability was also observed at up to 40 mN m-1. Although the C(14) material failed to deposit as an LB film, limited multilayer deposition (X or Z-type) was displayed by the other members in class I. In class II, only the di-cumylphenoxy-derivative of the cobalt(II) complex of TAA (CPTAACo, TAA as defined previously) was found to form satisfactory LB multilayers for which a surface pressure in the range 16-20 mNm-1 was employed. The Langmuir monolayers of the other members of this class were too rigid for LB deposition. Some observations concerning the effect of NOX upon an LB film of CPTAACo are described.