Toward a New Family of Bifunctional Organoiron Dendrimers: Facile Synthesis, Redox, and Photophysical Fingerprints

Abstract

Multifunctional macromolecules continue to attract attention. Here, three generations of a new family of bifunctional organoiron dendrimers are reported, which are synthesized from a redox-active organoiron complex, η 6 -dichlorobenzene-η 5 -cyclopentadienyl-iron(II). The facile chemistry of the complex is exploited to functionalize the dendritic peripheral with photoactive β-naphthol, yielding redox, photoactive dendrimers under mild conditions. To ascertain the redox and photophysical fi ngerprints of these dendrimers, cyclic voltammetric, and UV-vis and fl uorescence spectroscopic measurements are used. The cyclic voltammetric measurements suggest non-interacting redox-active iron centers within the dendritic structure, and a negative dendritic effect on the half-wave potential. The cathodic peak broadens with increasing dendrimer generation as the rate of electron transfer between the electrode and the iron centers decreases. The dendrimers exhibit the characteristic absorption and fl uorescence fi ngerprint of β-naphthol and a positive dendritic effect on the fl uorescence intensities. A 24 h UV irradiation of acetonitrile/chloroform solution of the dendrimers yields their organic analogues with a concomitant enhancement of the absorption and fl uorescence properties. The synthetic approach to these dendrimers offers an attractive route to other redox, multifunctional organometallic dendrimers.

Quaternized and Thiazole‐Functionalized Free Radical‐Generating Organometallic Dendrimers as Antimicrobial Platform against Multidrug‐Resistant Microorganisms

“…Typical of macromolecules derived from η 6 ‐dichlorobenzene‐η 5 ‐cyclopentadienyliron(II) complex, all the dendrimers were thermally stable up to 200 °C and degraded in three steps (Figure A). The first onset temperature ( T onset ) corresponds to cleavage of the cyclopentadienyliron(II) moieties and the subsequent thermal decomposition of the cyclopentadienyl ring as previously proved . The resulting organic dendrimer‐iron composite was stable up to 380 °C, after which rapid weight loss and volatilization occurred at the second and third T onset , respectively (Figure A).…”

“…As an example, the nonequivalent protons of the iron‐complexed chlorobenzene that resonated at 6.76 and 6.38 ppm shifted upfield to 6.21 ppm, resonating as a single broad peak (Figure SI1, Supporting Information) of equivalent protons after S N Ar reaction of DEN1 with 5(4‐hydroxyl)phenylpentanoic acid. Previously, we have shown that the splitting pattern and resonance frequencies of the iron‐complexed chlorobenzene change after S N Ar reaction of the chloro group . Moreover, the appearance and disappearance of peaks attributed to functional groups were diagnostic tools to monitor the successes of the synthesis steps.…”

“…The synthesis routes to DEN7 – DEN10 involved facile and well‐established chemistries. First, we obtained the η 6 ‐dichlorobenzene‐η 5 ‐cyclopentadienyliron(II) complex via the well‐established ligand exchange reaction of ferrocene with dichlorobenzene and then, DEN1 and DEN2 from this complex via a general synthesis route previously described . The synthesis of DEN7 or DEN8 involved nucleophilic aromatic substitution (S N Ar) reaction of DEN1 or DEN2 with 5(4‐hydroxyl)phenylpentanoic acid to give DEN3 or DEN4 in high yield after precipitation from 10% (v/v) aqueous HCl (Scheme ).…”

Photoinduced Synthesis of Dual‐Emissive Tetraphenylethene‐Based Dendrimers with Tunable Aggregates and Solution States Emissions

“…The synthetic route to the dendrimers is straightforward, exploiting the reactivity of η 6 ‐arene‐ η 5 ‐cyclopentadienyliron(II) toward a wide range of nucleophiles . For instance, to construct 0‐DEN‐TPE/DPP , η 6 ‐dichlorobenzene‐ η 5 ‐cyclopentadienyliron(II) was reacted with 4,4‐bis(4‐hydroxyphenyl)valeric acid via K 2 CO 3 ‐mediated nucleophilic aromatic substitution reaction (S N Ar), accessing the bimetallic building block (Scheme S2, Supporting Information).…”

Catalytically Active Palladium Nanoparticle‐Cored Ferrocenyl‐Terminated Dendrimers

“…Metallodendrimers [1][2][3][4][5][6] have attracted much attention as catalysts, [4][5][6][7][8][9][10][11][12] sensors, [13] and nanomaterials, [5] but nanoparticle-cored (NP-cored) dendrimers, that is, NPs decorated with dendrons, have relatively rarely been reported and examined. [14][15][16][17][18][19][20][21][22] Transition metal NPs, [23,24] in particular palladium NPs (PdNPs), [25][26][27][28][29][30][31] under a large variety of forms have been applied as catalysts for organic reactions and attracted considerable interest for years.…”