Synthesis of new star-like triply ferrocenylated compounds

Abstract

New ferrocenyl-subtituted compounds containing two different central cores (isocyanurate and 1,3,5-phenylene) and extended by two kinds of branches bearing both vinyl ferrocenyl (1 and 3) and cross-conjugated ferrocenyl-chalcone (2, 4 and 5) as endgroups have been synthetized and characterized both spectroscopically and electrochemically. These molecules have been synthesized in order to investigate the electronic properties imparted by both types of branches when they are connected to the central core. For all compounds, electrochemical studies have showed a simultaneous oxidation of all ferrocene units present in each compound. For all of them, except for compound 2, a chemically reversible oxidation wave on the voltammograms has been observed. In contrast, for compound 2, a chemically irreversible oxidation wave is obtained. Moreover, the vinyl ferrocenyl derivatives have presented a lower redox peak potential with respect to ferrocene standard compound, and the ferrocenyl-chalcone bearing derivatives, in accordance with a change in the electron releasing capability of these endgroups, have been oxidized at a higher potential. Bathochromic shifts of the active transitions in Uv-Vis region have been observed, which are associated to the presence of carbonyl groups in those molecular structures containing it. These results are in agreement with theoretically calculated transition energies, which have been obtained for compounds 1 and 2 using Time Dependent Density Functional Theory (TD-DFT).

A decacationic ferrocene-based metallostar

“…5 A widely used redox active building block is the ferrocenyl group due to the reversibility of the Fe +II/+III redox couple and the high thermal stability of the oxidized and the native form in particular. 6 In many molecular stars the metallocene unit is located in the outskirts of the molecule [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] despite its C 5 symmetry rendering it as an ideal core building block. Examples of ferrocene centered metallostars are rare 23,24 probably due to the synthetic difficulties associated with the poly-or perfunctionalization of ferrocene.…”

A Decacationic Ferrocene-Based Metallostar

“…[5] A widely used redox active building block is the ferrocenyl group due to the reversibility of the Fe +II/+III redox couple and the high thermal stability of the oxidized and the native form in particular. [6] In many molecular stars the metallocene unit is located in the outskirts of the molecule [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] despite its C5 symmetry rendering it as an ideal core building block. Examples of ferrocene centered metallostars are rare [23,24] probably due to the synthetic difficulties associated with the poly-or perfunctionalization of ferrocene.…”