Synthesis and characterization of eight new tetraphenylporphyrins bearing one or two ferrocenes on the β-pyrrole positions

Abstract

One or two ferrocenes were linked to the b-pyrrole positions of the free base TPP or its zinc complex through an ethynyl or ethynylenephenylene group using a modification of the Sonogashira method. All the compounds were characterized using UV-vis, FAB-mass and NMR spectroscopy and cyclic voltammetry.Ferrocenes and porphyrins are among the most intriguing molecules due to their electrochemical and catalytic properties. Several studies were devoted to their reciprocal interactions through the covalent bonds or supramolecular contacts. 1Many dyads or triads containing ferrocenes and porphyrins were synthesized in order to investigate the energy and/or electron transfer induced by light.2 Furthermore, different p-conjugated organic bridges were proposed and investigated as connecting molecular wires between several chromophores. They include oligo-phenylenevinylene, 3 oligo-phenyleneethynylenes, 4 oligo-acetylenes, 5 oligo-thiophenes, 6 and oligophenylenes. 7 In all these cases the wire-like behavior -efficient or inefficient -depends on the combination of several factors including the degree of conjugation in the bridge, orbital matching, donor-bridge energy gap, etc. 8During our investigations on the electronic properties of dyads containing porphyrins and fullerenes, we reported on the properties of dyads containing such monomers linked by oligo-ethynylenephenylene bridges. 9 The presence of one or more triple bonds connecting porphyrins and ferrocenes can provide interesting and unusual properties to the dyads due to their reciprocal electronic interactions and the rigidity of the structure.

Functionalization of Carbon Spheres with a Porphyrin−Ferrocene Dyad

“…This suggests that conjugation is more extended in the triads, and the porphyrin HOMO spreads more along the whole length of the linker. In this respect, the behaviour of the new triad compounds is distinct from that of the previouly reported ones and more similar to those recently investigated by our group . This confirms that the ferrocene unit favours delocalization of charge along the carbon−carbon triple bonds.…”

“…Porphyrin-ferrocene compound 4 was synthesized as reported in the literature. [28] Dyad 5. 60 mg (0.058 mmol) of compound 4 were dissolved in 30 mL of CHCl 3 and 1 mL of saturated solution of Zn(AcO) 2 in methanol was added.…”

Flexible Tuning of Unsaturated β‐Substituents on Zn Porphyrins: A Synthetic, Spectroscopic and Computational Study

“…Tagliatesta et al. synthesised Zn porphyrins with CC‐Fc or CC‐Ph‐Fc (in which Fc=ferrocene) at adjacent β‐positions and found B bands to be at 445 and 449 nm, respectively 27. This is comparable to the compounds studied here, which also have triple‐bond containing groups that extend conjugation in adjacent β‐positions, although it does not appear to be a requirement that the substituents are adjacent to have this effect.…”

“…[4] Tagliatesta et al synthesised Zn porphyrins with CC-Fc or CC-Ph-Fc (in which Fc = ferrocene) at adjacent b-positions and found Bb ands to be at 445 and 449 nm, respectively. [27] This is comparable to the compounds studied here, which also have triple-bond containinggroupsthat extend conjugation in adjacent b-positions, although it does not appear to be ar equirementt hat the substituents are adjacentt oh ave this effect. The most electrondonating substituent in the para position of the ethynyls ubstituentp henyl ring (H, Zn 2c)g ives the broadest Bb and;t hat with the most electron-withdrawings ubstituent (CF 3 ,Z n2b) showst he narrowest band.…”

Designing Cascades of Electron Transfer Processes in Multicomponent Graphene Conjugates

“…Various references were used in the following sections: commercially available zinc‐tetraphenylporphyrin( ZnTPP ), Fc‐ZnP based conjugates ( HZnPa , HZnPb , (Figure S1)), [52] a β‐substituted zinc porphyrin‐based reference ( β‐ZnP‐ref ) [32] (Figure S2), and 5‐GNP (Figure S3).…”