Synthesis and photophysics of a linear non-covalently linked porphyrin–fullerene dyad

Abstract

The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with ZnTPP is reported; molecular modelling studies, 1H NMR, UV-Vis spectroscopy and fluorescence quenching data support formation of a strong complex between the new ligand and ZnTPP.

Synthesis of Fullerene Adducts with Terpyridyl‐ or Pyridylpyrrolidine Groups in trans‐1 Positions

“…One singlet for the pyrrolidine ring protons and two different quartets and triplets for the methylene and methyl groups on the malonate belt clearly indicate a D 2h symmetry for compound 2, that is, all the addends are located at octahedral positions (trans-1 bis(pyrrolidine) and equatorial malonate moieties). In addition, 30 sets of equivalent carbon signals in the 13 C NMR spectrum are consistent with the proposed D 2h symmetry of compound 2 (see the Supporting Information). In the case of compound 9, three quartets with a ratio of 1:1:2 were observed at d = 4.24-4.28, 4.29-4.33, 4.34-4.37 ppm for the methylene groups of the malonate adducts, consistent with the symmetry of the compound.…”

“…In 2003, Wilson et al prepared a pyridinofulleropyrroline derivative (1) which exhibited effective electronic coupling between the C 60 core and the pyridyl nitrogen atom, as confirmed by 1 H NMR spectroscopy, molecular modeling studies, UV-visible spectroscopy, and fluorescent-quenching experiments (Scheme 2). [13] Electrochemical studies further confirmed this effective coupling between the pyridyl nitrogen atom and the fullerene core based on the fact that the first reduction of the C 60 core was shifted by 40 mV upon complexation with a Zn-porphyrin derivative. [14] Thus C 60 hexakis-adducts 2 and 3 with terpyridyl or pyridyl groups in the trans-1 positions and the corresponding trans-1 bis-adducts 4 and 5 (Scheme 3) were selected as the synthetic targets in the present work.…”

“…Terpyridylglycine was eventually synthesized in 73 % yield by treating ATP with ethyl glyoxylate and concentrated HCl followed by reductive hydrogenation. [27] The characterization of terpyridylglycine was established on the basis of MALDI-TOF mass spectrometry, and 1 H, 13 C, and COSY NMR spectroscopy (see the Supporting Information).…”

“…It is interesting to observe that mono(terpyridyl) compound 9 was always present even after increasing the reaction time and/or by using a large excess of paraformaldehyde and terpyridylgylcine. Compounds 2 and 9 were characterized by means of MALDI-TOF MS, and 1 H, 13 C, and COSY NMR, and UV-visible spectroscopy. Figure 1 shows the 1 H NMR spectra of compound 2.…”

“…By using the retro-cyclopropanation reaction, the four malonate addends located on the equatorial belt of the hexakis-adducts were removed to afford two trans-1 bis-adducts, 4 and 5, with terpyridylor pyridylpyrrolidine groups. The structures of 2 and 3 were confirmed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and 1 H, 13 C, and COSY NMR, and UV-visible spectroscopy. The cyclic voltammograms of fullerene multiadducts 2, 3, and 9 show irreversible reductions.…”