Synthesis of electroactive multinuclear dipyrrinato complexes and Fe(iii) assisted formation of α-alkoxy substituted 5-ferrocenyldipyrromethenes

Abstract

The synthesis and characterization of multinuclear complexes [Pd(acac)(fcdpm)] (1), [Pd(fcdpm)(2)] (2), [Co(acac)(fcdpm)(2)] (3), [Co(fcdpm)(3)] (4) and α-alkoxy derivatives [α-OMe-fcdpm] (5), [α-OEt-fcdpm] (6), [α-OPr(n)-fcdpm] (7) and [α-OBu(n)-fcdpm] (8) (fcdpm = 5-ferrocenyldipyrromethene; acac = acetylacetone) have been described. Formation of alkoxy derivatives 5-8 takes place from highly selective Fe(III) mediated alkoxylation of fcdpm in alcohol. It has been established that yield of α-alkoxy derivatives depend on the alcohol chain length. The compounds under study have been characterized by elemental analyses, spectral (IR, (1)H, (13)C NMR, ESI-MS, UV-vis) and electrochemical studies (CV and DPV). Structures of 1, 3 and 5 have been verified by X-ray single crystal analyses. Structural studies revealed distorted square planar and octahedral geometry about Pd(II) and Co(III) centres. All the compounds exhibited oxidation wave due to Fc/Fc(+) redox couple (0.34-0.36, 1-4; 0.24-0.25 V, 5-8).

Sequential Nucleophilic Substitution of the α‐Pyrrole and p‐Aryl Positions of meso‐Pentafluorophenyl‐Substituted BODIPYs

“…With the exception of compound 7c (Scheme ), all functionalized target BODIPYs were obtained, which showed that such α‐substituted dipyrrins could provide access to α‐substituted BF 2 complexes. The yields depended on the alkoxy chain length, and longer chains gave lower yields or no product formation, which is in line with the observations of Pandey et al for dipyrrins. To the best of our knowledge, this is the first report of α‐alkoxy‐substituted BODIPYs.…”

“…[13b] Alternatively, such alkoxy substitution could be performed on the respective dipyrrin. Examples of this have been published (see discussion above) …”

“…The following steps required the presence of a metal salt. Pandey et al achieved the best results with FeCl 3 · 6H 2 O. Thus, dipyrrins underwent reaction with an alcohol in the presence of Et 3 N and FeCl 3 · 6H 2 O to afford the corresponding α‐monoalkoxy‐substituted dipyrrins (Scheme ).…”

“…Heating of the primary DDQ adduct in MeOH at reflux in the presence of AlCl 3 yielded an α‐methoxy‐substituted product (Scheme c) . Specifically, Pandey and co‐workers reported an Fe III ‐mediated one‐pot procedure in the presence of a base and an alcohol to obtain the desired α‐alkoxy‐substituted dipyrrin directly from the nonsubstituted dipyrrane (Scheme d) …”

Insight into the optical properties of meso-pentafluorophenyl(PFP)-BODIPY: An attractive platform for functionalization of BODIPY dyes

“…[13] In addition, the dipyrromethene precursor is a highly unstable compound, [14] difficult to isolate unless appropriate substituents and synthetic strategies are adopted. [15][16][17][18][19][20] For example, the stabilization induced by the electron withdrawing PFP substituent allows the synthesis of α-monoalkoxy-substituted dipyrrins, [19] (recall atom labeling inherited from the BODIPY dipyrrin unit, [9] porphyrins and other porphyrinoids [21,22] in Scheme 1), from their dipyrrane precursor.…”