Interfacial Behavior and Film Patterning of Redox‐Active Cationic Copper(II)‐Containing Surfactants

Abstract

Herein, we describe the synthesis and characterization of a novel series of single-tail amphiphiles LPyCn (Py=pyridine, Cn=C18, C16, C14, C10) and their copper(II)-containing complexes, which are of relevance for patterned films. The N-(pyridine-2-ylmethyl)alkyl-1-amine ligands and their complexes [CuIICl2(LPyC18)] (1), [CuIICl2(LPyC16)] (2), [CuIICl2(LPyC14)] (3), [CuIIBr2(LPyC18)] (4), [CuIIBr2(LPyC16)] (5), and [CuIIBr2(LPyC10)] (6) were synthesized, isolated, and characterized by means of mass spectrometry, IR and NMR spectroscopies, and elemental analysis. Complexes 1, 2, 3, and 6 had their molecular structure solved by X-ray diffraction methods, which showed that the local geometry around the metal center is distorted square planar. With the aim of using these species as precursors for redox-responsive films, an assessment of their electrochemical properties involved cyclic voltammetry in different solvents, with different supporting electrolytes and scan rates. Density functional theory calculations of relevant species in bulk and at interfaces were used to evaluate their electronic structure and dipole moments. The morphology and order of the resulting films at the air/water interface were studied by isothermal compression and Brewster angle microscopy. Biphasic patterned Langmuir films were observed for all complexes except 3 and 6, and dependence on the chain length and the nature of the halogen coligand determine the characteristics of the isotherms and their intricate topology. Complexes 3 and 6, which have shorter chain lengths, failed to exhibit organization. These results exemplify the first comprehensive study of the behavior of single-tail metallosurfactants, which are likely to lead to high-end technological applications based on their patterned films.

Copper(II) Complexes Containing N,N′‐Bidentate N‐(Pyridin‐2‐ylmethyl)aniline and Its Derivatives: Synthesis, Structure and Magnetic Property

“…Specifically, dinuclear or polynuclear copper(II) complexes have long metal–metal distances, and their interaction shows interesting behavior, such as magnetic properties . Consequently, they exert specific chemical properties and applications when they are adopted in various materials . The reported N,N′ ‐bidentate ligands, N ‐(pyridin‐2‐ylmethyl)aniline ( L a ), 2,4,6‐trimethyl‐ N ‐(pyridin‐2‐ylmethyl)aniline ( L b ), 2,6‐dimethyl‐ N ‐(pyridin‐2‐ylmethyl)aniline ( L c ), and their derivatives have been applied to transition metals, such as palladium, ruthenium, vanadium, zirconium, zinc, and copper .…”

Molecular Order in Langmuir−Blodgett Monolayers of Metal−Ligand Surfactants Probed by Sum Frequency Generation

“…A series of novel surfactants with a pyridine-based metal-chelating head group have been developed recently and shown to exhibit amphiphilic behavior and film pattern formation . In this paper, we focus on the molecular organization in the LB monolayers of the chelating surfactant octadecyl-pyridin-2-ylmethyl-amine (L PyC18 ), 1 , its singly coordinated copper complex (L PyC18 Cu II Cl 2 ), 2 , and doubly coordinated copper complex [(L PyC18 ) 2 Cu II ]Cl 2 , 3 [two ligands coordinated to one copper(II) ion], depicted in Scheme .…”

Structure–property relationships in metallosurfactants

“…The absorption spectra for all the complexes examined were found to be insensitive to changes in the nature of the counter-ion, indicating that the counter-ions do not coordinate to the metal centres and that these species are fully ionised in solution and may be regarded as 1 : 2 electrolytes or a 1 : 1 electrolyte in the sulfate case. Thus, and in contrast to those amphiphiles in which counter-ions occupy positions in the primary coordination sphere, 24 these materials might be expected to be insensitive to changes in the nature of the counter-ions. The pH values of 25 mM stock solutions of the metallosurfactants were found to be in the range of 6.0-7.4 for the Ni II species and 4.9-5.9 in the case Cu II .…”