A Comparative Study of Cryptand-Based (Triple-Head and Triple-Tail) Amphiphiles at the Air−Water Interface

Two cryptands have been derivatized by reacting with acid chlorides of different alkyl chain lengths (between C<sub>4</sub> and C<sub>18</sub>) to get a set of cryptand-based (triple-head and triple-tail) neutral amphiphiles. The cavity of either cryptand headgroup can accommodate a first-row transition metal ion forming stable cryptates. The free as well as the Cu(II)-complexed amphiphiles are studied at the air−water interface in a Langmuir−Blodgett trough. They form stable monolayers at the air−water interface, which can be transferred onto different substrates (viz., glass, fluorite, and quartz). They form Y-type Langmuir−Blodgett films. The amphiphile <b>L</b><b><sub>5</sub></b> crystallizes in the monoclinic space group <i>P</i>2<sub>1</sub>/<i>c</i> with <i>a</i> = 10.091(3) Å, <i>b</i> = 29.994(8) Å, <i>c</i> = 18.174(5) Å, <i>Z</i> = 4, <i>R</i><sub>f</sub> = 0.1048, <i>R</i><sub>wf</sub> = 0.2660, and GOF = 0.925. The amphiphile <b>L</b><b><sub>6</sub></b> crystallizes in the trigonal space group <i>P</i>31<i>c</i> with <i>a</i> = 15.118(2) Å, <i>b</i> = 15.118(2) Å, <i>c</i> = 11.734(2) Å, <i>Z</i> = 2, <i>R</i><sub>f</sub> = 0.033, <i>R</i><sub>wf</sub> = 0.062, and GOF = 0.813. The solid-state structures of both the amphiphiles show a 3-fold symmetry about a point in the center of the cryptand headgroup. The hydrophobic tails of the cryptands are packed in the lattice both in interdigitizing and in noninterdigitizing manners.