A Decade Journey in the Chemistry of Sandwich-Type Tetrapyrrolato−Rare Earth Complexes

Abstract

Phthalocyanines and porphyrins are versatile functional pigments with a wide range of applications. These macrocyclic compounds contain four isoindole or pyrrole nitrogen atoms, which can complex with a range of metal ions. Large rare earth metal ions can bring together these tetrapyrrole derivatives to form sandwich-type double- and triple-decker complexes. Depending on the metal centers and the nature of the macrocyclic ligands, these compounds exhibit tunable spectroscopic, electronic, and redox properties, and different extents of intramolecular pi-pi interactions. Some of the properties of the sandwich-type complexes are unique and enable them to be used as advanced materials for various applications. Over the last two decades, a vast number of homoleptic and heteroleptic double- and triple-decker complexes have been synthesized. With improvements in synthetic procedures, researchers have prepared novel sandwich complexes that could not have been prepared by traditional methods. This Account highlights our work over the last decade on this important class of compounds. We have focused both on the development of facile and efficient synthetic methodology and on the various properties and potential applications of these complexes. For both the double- and triple-decker series, we have performed systematic investigations on several series of closely related analogues to reveal the correlations among the structures, electronic properties, spectroscopic characteristics, electrochemistry, and degree of pi-pi interactions. We have also performed detailed studies of the self-assembly of amphiphilic analogues in Langmuir-Blodgett films, metal-induced assembly of crown ether containing sandwich compounds, and the use of these complexes in organic field-effect transistors.

Orientation-Induced Redox Isomerism in Planar Supramolecular Systems

“…DRAS of monolayers are shown in Figure 5 with the UV−vis spectrum of the complex solubilized in chloroform at a concentration of 1.6 × 10 −5 M. This last one ( Figure 5, curve 1) is characterized by the presence of two intense bands at 650 and 700 nm (Q bands) and a broad band centered at 500 nm, that is typical for the bisphthalocyanine compounds. 18,25,26,34,47,48 The band at 500 nm indicates the presence of an unpaired electron in the double decker crown phthalocyaninate. The ratio of intensities of bands at 650 and 700 nm is indicative of the valent state of the cerium atom: in the case of Ce 4+ short wavelength part of the Q band is prevalent, and in the case of Ce 3+ , this part 4 Pc] 2 LBF on mica substrate obtained in contact mode after a scratching experiment.…”

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

“…37 There are 4n+2 π electrons in the middle of phthalocyanines. It was revealed that the π electrons are strongly delocalized around the chromophore, which renders high thermal and chemical stability that can endure intense electromagnetic radiation.…”

Revisiting the One-Step Synthesis of Heteroleptic Lanthanide(III) (Porphyrinato)(Phthalocyaninates): Opportunities and Limitations

“…[14] The typical approach consists in stepwise construction of the target molecule starting from the formation of lanthanide mono-porphyrinate or phthalocyaninate, with subsequent introduction of the following ligand or its precursor. [11,[15][16][17] Another case is the interaction between in situ generated lanthanide mono-porphyrinate and a pre-synthesized double-decker complexes. [17][18][19] Altogether these approaches allow preparation of various heteroleptic lanthanide complexes containing equal or different metal centers for electrochemical or magnetic application.…”