TY  - JOUR
AU  - Metzelaars, Marvin
AU  - Sanz, Sergio
AU  - Rawson, Jeff
AU  - Hartmann, Rudolf
AU  - Schneider, Claus M.
AU  - Kögerler, Paul
TI  - Fusing pyrene and ferrocene into a chiral, redox-active triangle
JO  - Chemical communications
VL  - 57
IS  - 54
SN  - 0009-241X
CY  - Cambridge
PB  - Soc.
M1  - FZJ-2021-04399
SP  - 6660 - 6663
PY  - 2021
AB  - Fundamental understanding and control of electron transfer processes in molecular building blocks are key to construct nanoscale (spin)electronic devices. Ferrocene (Fc) has been studied extensively in this context due to high conductance and stability, and its well-defined and reversible redox-switching behaviour.1 The integration of multiple Fc groups into a single, nonlinear molecule (e.g. stars2 or macrocycles3) generates materials with extraordinary electronic properties that might not be observed in linear analogues. So far only a handful of shape-persistent and cyclic Fc-based compounds have been synthesised by linking Fc groups either directly3g,h or via simple bridging units, like diethynylbenzene derivatives.3c–eUsing the larger aromatic building block pyrene (Py), we can tune the properties for a range of applications. The Py group is fundamental in host–guest chemistry, used in metallacycles and -cages to entrap fullerenes and other guests.4 Preuß et al. used linear ferrocenyl–pyrenes to disentangle and functionalise carbon nanotubes via π–π stacking.5 We showed that a Fc-bridged pyrenophane can be sublimed onto ferromagnetic surfaces to craft 3D spin interfaces.6 The photophysical properties of pyrene have been exploited in phototransistors, “turn-on” sensors and fluorescence switches based on Fc–Py dyads.7To construct a macrocycle with two different functional units often entails protracted, stepwise synthesis. We recently demonstrated a one-step Suzuki–Miyaura cross-coupling (SMC) route to an insoluble, pyrene-based cyclophane in <1% yield (Chart 1, cyclophane). By this method, we synthesised a soluble macrocycle of three Fc–Py dyads bonded into a triangle (Chart 1, 3). Employing 2,7-bis(Bpin)pyrene as linear and 1,1′-diiodoferrocene as angular building blocks, our optimised conditions gave a yield of 6% (PdCl2(dtbpf) in DMF). The Fc group adopts a range of angles to serve as a vertex in linear and larger cyclic oligomers with low solubility, which we could detect by mass spectrometry of crude reaction mixtures, albeit not isolate. Soluble side products, likely generated via dehalogenation or deborylation of acyclic intermediates, were also identified (see Fig. S12 and S13†). We synthesised noncyclic molecules 1 and 2 that complete the series in Chart 1. The identity of dyad 1, stack 2 and triangle 3 were confirmed by 1H/13C-NMR (Fig. S1–S7†), MALDI-HRMS (Fig. S8–S11†), and elemental analysis.
LB  - PUB:(DE-HGF)16
C6  - pmid:34128505
UR  - <Go to ISI:>//WOS:000661559200001
DO  - DOI:10.1039/D1CC02191E
UR  - https://juser.fz-juelich.de/record/902604
ER  -