Synthesis and Characterization of Rare Earth Corrole–Phthalocyanine Heteroleptic Triple-Decker Complexes

Abstract

We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole-phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M2[Pc(OC4H9)8]2[Cor(ClPh)3], where Pc = phthalocyanine, Cor = corrole, and M is Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), or Tb(III). The Y(III) derivative with OC4H9 Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y2[Pc(OC5H11)8]2[Cor(ClPh)3] was synthesized and characterized in a similar manner. The molecular structure of Eu2[Pc(OC4H9)8]2[Cor(ClPh)3] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with E1/2 values being linearly related to the ionic radius of the central ions. The energy (E) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole-phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles.

Dysprosium Heteroleptic Corrole-Phthalocyanine Triple-Decker Complexes: Synthesis, Crystal Structure, and Electrochemical and Magnetic Properties

“…1 Figures S3 and S4 in the Supporting Information display the IR spectra of complexes 1 and 2 in the region of 400−4000 cm −1 , respectively. Due to the similarity of their molecular structures to those of the previously reported M 2 [Pc-(OC 4 H 9 ) 8 ] 2 [Cor(ClPh) 3 ] derivatives (where M = Pr−Tb except Pm), 50 complexes 1 and 2 show similar IR characteristics. Observation of an intense absorption at 1381 cm −1 together with a very weak band at 1312 cm −1 well defines the characteristics of the dianionic nature of phthalocyanine in complexes 1 and 2.…”

“…Synthesis. According to our previously described procedure, 49−52 49 and M 2 [Pc(OC 4 H 9 ) 8 ] 2 [Cor(ClPh) 3 ] (16−31% for M = Pr−Tb, except Pm) 50 by using the same method but higher than that of Y 2 [Pc(OC 5 H 11 ) 8 ] 2 [Cor(ClPh) 3 ] (1%). Apparently, the size of the central metal has an effect on the yield of these compounds.…”

“…Electronic Absorption Spectra. The electronic absorption spectra of compounds 1 and 2 were recorded in CH 2 Cl 2 , and the data are summarized in Table S1 in the Supporting Information, which also includes data for the earlier reported Eu(III) and Y(III) derivatives 50,51 and the radius of the rareearth ion of each compound. 59 Figure 1 shows their electronic absorption spectra in the range of 250−1000 nm, which shows the typical features observed in the electronic absorption spectra of rare-earth heteroleptic triple-decker corrole-phthalocyanine complexes.…”

“…According to our previously described procedure, − the target complexes 1 and 2 were obtained by prior generation of the “half-sandwich” phthalocyanine complex Dy­[Pc­(OC 5 H 11 ) 8 ]­(acac) from H 2 [Pc­(OC 5 H 11 ) 8 ] , and Dy­(acac) 3 · n H 2 O in refluxing DMF, followed by treatment with the corresponding free-base corrole H 3 [Cor­(FPh) 3 ] or H 3 [Cor­(ClPh) 3 ] in n -octanol containing DBU at reflux and purified by repeated chromatography with CHCl 3 as eluent. The yields for both complexes (10% for 1 and 8% for 2 ) were lower than those for their analogous complexes Eu 2 [Pc­(R) 8 ] 2 [Cor­(ClPh) 3 ] (15–16% for R = H, OC 5 H 11 , OC 8 H 17 ), , Eu 2 [Pc­(OC 4 H 9 ) 8 ] 2 [Cor­(Ph) n (NO 2 Ph) 3– n ] (40–54% for n = 0–3), and M 2 [Pc­(OC 4 H 9 ) 8 ] 2 [Cor­(ClPh) 3 ] (16–31% for M = Pr–Tb, except Pm) by using the same method but higher than that of Y 2 [Pc­(OC 5 H 11 ) 8 ] 2 [Cor­(ClPh) 3 ] (1%). Apparently, the size of the central metal has an effect on the yield of these compounds.…”

“…The first example of lanthanide corrole complexes (of La, Gd, and Tb), which shows their potential use as fluorescence imaging agents, was reported by Arnold et al in 2013 . In recent years, we have successfully synthesized several rare-earth corrole-phthalocyanine heteroleptic triple-decker complexes M 2 Pc* 2 Cor* (M = Y, Pr, Nd, Sm, Eu, Gd, Tb), which exhibit potential applications in the area of molecular-based information storage devices. − …”