A route to hierarchical materials based on complexes of metallosupramolecular polyelectrolytes and amphiphiles

Abstract

Anisotropic thin film materials of metallosupramolecular polyelectrolyte-amphiphile complexes (denoted PACs) with structures at several length scales were fabricated through a multistep self-assembly process. Metal ion-mediated self-assembly of the ditopic ligand 1,4-bis(2,2:6,2-terpyridine-4-yl)benzene and electrostatic binding with the amphiphile dihexadecyl phosphate result in a PAC with tailored surface chemical properties, including solubility and surface activity. The PAC forms a stable monolayer at the air-water interface that is readily transferred and oriented on solid supports with the Langmuir-Blodgett technique. The presented strategy unifies colloid and metallosupramolecular chemistry and opens a versatile route to hierarchical materials with tailored structures and functions.T he design and construction of supramolecular architectures of nanoscopic dimensions give access to entities of increasing complexity with distinct structural and functional properties (1). The use of intermolecular forces provides a rational and efficient method to position molecular components precisely in a well defined supramolecular architecture (2). Self-assembly relies on a sequence of spontaneous recognition, growth, and termination steps to form the final equilibrium supramolecular entity (or a collection of such) through metal ion coordination, hydrogen bonds, or hydrophobic or electrostatic interactions. Applications of such systems in materials science, medicine, and chemical technology are diverse, including recognition (sensing), transformation (catalysis), and translocation (signal transduction) devices.Although the principles that govern self-assembly of discrete supramolecular assemblies are well understood, the fabrication of (extended) structures with more than one length scale is the next challenge in the implementation of supramolecular devices in functional materials (3). Correlation of positions and orientations of the constituents in a material, preferentially over a long range, is of paramount importance to exploit the properties of supramolecular devices fully, for example in vectorial transport processes, such as light-to-energy conversion, or to establish an electronic band structure as in semiconductors (4 -6). To achieve this goal, it will be necessary to improve existing and to innovate new methods to fabricate hierarchical materials. The Langmuir-Blodgett (LB) technique was one of the first methods to fabricate films with a well defined architecture and played a key role in the development of molecular electronics (7). Other approaches include the engineering of crystals (8), liquid crystalline materials, and lyotropic mesophases (9). However, the implementation of metallosupramolecular devices in ordered hierarchical architectures has not been realized to date.Metal-ion-directed self-assembly is of particular interest for the construction of functional devices (10). Metal ions possess a range of well defined coordination geometries and diverse properties that are relevant in electronic and phot...

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Supramolecular routes towards liquid crystalline side-chain polymers

“…15). 85 Interestingly, the complexes showed 6 DHP molecules per polymer repeat unit, rather than the minimum of two needed for charge neutralization. The other surfactants must be kept in place via hydrogen bonding (note that DHP contains both H-bond donor and acceptor sites).…”

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Transport and Electro‐Optical Properties in Polymeric Self‐Assembled Systems

“…blocks. The interactions can be ionic [43,[53][54][55][56][57][58][59][60][61][62][63][64][65][66], in which case the term ionic self-assembly can be used [42]; they can be hydrogen bonds or their combinations [10,11,21,22,34,; they can be coordinative [89][90][91][92][93]; or they can in principle be any sufficiently strong attractive interaction or their combination. Over the years, several examples have arisen of physical interactions that enable one to prepare polymer-like materials (Figs.…”