Designing supramolecular porphyrin arrays that self-organize into nanoscale optical and magnetic materials

Abstract

Tessellation of nine free-base porphyrins into a 3 ؋ 3 array is accomplished by the self-assembly of 21 molecular entities of four different kinds, one central, four corner, and four side porphyrins with 12 trans Pd(II) complexes, by specifically designed and targeted intermolecular interactions. Strikingly, the self-assembly of 30 components into a metalloporphyrin nonamer results from the addition of nine equivalents of a first-row transition metal to the above milieu. In this case each porphyrin in the nonameric array coordinates the same metal such as Mn(II), Ni(II), Co(II), or Zn(II). This feat is accomplished by taking advantage of the highly selective porphyrin complexation kinetics and thermodynamics for different metals. In a second, hierarchical self-assembly process, nonspecific intermolecular interactions can be exploited to form nanoscaled three-dimensional aggregates of the supramolecular porphyrin arrays. In solution, the size of the nanoscaled aggregate can be directed by fine-tuning the properties of the component macrocycles, by choice of metalloporphyrin, and the kinetics of the secondary self-assembly process. As precursors to device formation, nanoscale structures of the porphyrin arrays and aggregates of controlled size may be deposited on surfaces. Atomic force microscopy and scanning tunneling microscopy of these materials show that the choice of surface (gold, mica, glass, etc.) may be used to modulate the aggregate size and thus its photophysical properties. Once on the surface the materials are extremely robust.

Self-Assembly and Properties of Nonmetalated Tetraphenyl-Porphyrin on Metal Substrates

“…[6][7][8][9] The selfassembly is mainly driven by noncovalent metal−organic coordination interactions, which is well-known and important in solution-based 3D supramolecular chemistry. [10][11][12][13][14][15] Porphyrin molecules have been adsorbed onto surfaces to form supramolecular networks from solution, [16][17][18][19] electrochemically 20,21 or by thermal evaporation under vacuum conditions. [22][23][24][25][26][27][28] While there is a rich literature on the electronic structure of these adsorbates, the surface adlayer structures have also been characterized with scanning force microscopy, scanning tunneling microscopy, or X-ray absorption near-edge structure analysis.…”

Photophysical Properties and Aggregation Behavior of Transition Metal Tetraphenylporphyrin Tetrasulfonate Complexes in Microheterogeneous Media

“…[1][2][3] Such smart materials can include either homoporphyrin aggregates (H-or J-type ones) or multiporphyrin assemblies, [4] as well as heteroaggregates [5] and ionic associates with various non-porphyrin compounds. [6] Since both photophysical and photochemical properties of various porphyrin derivatives strongly depend on the chromophore aggregation state determined predominantly by the medium acidity, ionic strength and the presence of template molecules, controlled reversible aggregation of porphyrin supramolecular assemblies is still of great research interest.…”

Synthesis and Spectroscopic Studies of Zirconium(IV) Porphyrins with Acetylacetonate and Phenolates at Axial Positions

“…The metal ions in these complexes are oxophilic; thus, the preference for carboxylate or other oxygen-bearing anionic ligands. Zr(IV) has an electron configuration of [Kr]4f 14 , is closed shell metal ion and Because of the lack of functional groups on the porphyrin moieties, there is a paucity of supramolecular materials with designed, hierarchical structures [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] containing Zr(Por). The key entry to the organometallic zirconium porphyrin complexes would be Zr-(Porphyrin)Cl 2 , analogous to ZrCp 2 Cl 2 .…”