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Supramolecular Phthalocyanine-Based Systems

Molecular Recognition

  1. Christian G. Claessens1,
  2. M. Victoria Martínez-Díaz1,
  3. Tomás Torres1,2

Published Online: 15 MAR 2012

DOI: 10.1002/9780470661345.smc060

Supramolecular Chemistry: From Molecules to Nanomaterials

Supramolecular Chemistry: From Molecules to Nanomaterials

How to Cite

Claessens, C. G., Martínez-Díaz, M. V. and Torres, T. 2012. Supramolecular Phthalocyanine-Based Systems. Supramolecular Chemistry: From Molecules to Nanomaterials. .

Author Information

  1. 1

    Universidad Autónoma de Madrid, Madrid, Spain

  2. 2

    IMDEA-Nanociencia, Madrid, Spain

Publication History

  1. Published Online: 15 MAR 2012

Abstract

Phthalocyanines (Pcs) represent one of the most widely studied macrocyclic aromatic ring systems. Their intrinsic electronic delocalization, the presence of central metals, and the introduction of appropriate peripheral and/or axial functionalization give rise to numerous features that allow the organization of these macrocycles at a supramolecular level. Noncovalent interactions have a strong influence on Pc properties, including photoinduced electron- and energy-transfer events that have inspired the development of supramolecular Pc-based systems as photosynthetic model systems. In this chapter, the propensity of Pcs to self-aggregate by strong π–π interactions, as well as the influence of the central metal ion and the solvent in the preferential aggregation modes, is highlighted. The π-stacking as a basic feature for the self-assembling of Pcs, particularly the donor–acceptor (D–A) interactions between complementary electron-deficient and electron-donor molecular components, is analyzed. Further attention is devoted to the strong and directional metal–ligand interactions that are among the most popular molecular recognition tools for the construction of well-defined supramolecular architectures based on Pcs. The discussions are mainly centered on zinc(II) and ruthenium(II) phthalocyanines. Concerning Pc-analogs, subphthalocyanines (SubPcs) containing pyridyl substituents have been assembled into supramolecular capsules through peripheral pyridine–Pd–pyridine complexation. On the other hand, electrostatic interactions are also presented as a simple way to form Pc face-to-face hetero-ensembles by self-assembly of adequate components bearing oppositely charged substituents. The introduction of crown-ether subunits at the periphery of the macrocycle also allows complexation of exocyclic metals, which may be used for supramolecular organization of these systems. The influence of hydrogen-bonding interactions on the aggregation properties of Pcs has also been highlighted. Finally, the noncovalent interactions that allow the organization at the nanoscale level of Pcs and SubPcs on different surfaces are analyzed utilizing a wide range of scanning probe microscopies.

Keywords:

  • phthalocyanines;
  • subphthalocyanines;
  • supramolecular chemistry;
  • hydrogen bonding;
  • metal–ligand interactions;
  • donor–acceptor interactions;
  • nanoscience