Complexation and Electronic Communication between Corannulene‐Based Buckybowls and a Curved Truxene‐TTF Donor

Abstract

The association behavior of an electron-donating, bowl-shaped, truxene-based tetrathiafulvalene (truxTTF) with two corannulene-based fullerene fragments, ÀC 32 H 12 and C 38 H 14 À, is investigated in several solvents. Formation of 1:1 complexes is followed by absorption titrations and complemented by density functional theory (DFT) calculations. The binding constants are in the range log K a = 2.9-3.5. DFT calculations reveal that the most stable arrangement is the conformation in which the 1,3-dithiole ring of truxTTF is placed inside the concave cavity of the corannulene derivative. This arrangement is confirmed experimentally by NMR measurements, and implies that a combination of p-p and CH-p interactions is the driving force for association. Timedependent DFT calculations reproduce the experimental UV/ Vis titrations and provide a detailed understanding of the spectral changes observed. Femtosecond transient absorption studies reveal the processes occurring after photoexcitation of either C 32 H 12 or C 38 H 14 and their supramolecular associates with truxTTF. In the case of truxTTF·C 38 H 14 , photoexcitation yields the charge-separated state truxTTFC + ·C 38 H 14 C À with a lifetime of approximately 160 ps.

Supramolecular Assemblies for Electronic Materials

“…Over the course of the titration, we observe the largest perturbations in the downfield shifts of phenyl aromatic protons H d and H e (Δ δ =0.18 ppm, Figure a, c and Figures S6.1–S6.3), indicative of intermolecular π–π aromatic stacking interactions between fullerene guest and aromatic belt of the PBPB macrocyclic host . This was supported by upfield shifts of the fullerene resonances in the 13 C NMR spectrum, consistent with a ring current effect from the diamagnetic aromatic system of the macrocycle (Figures b, c, S6.9, and S6.10) .…”

“…[31] Over the course of the titration, we observe the largestp erturbationsi nt he downfield shifts of phenyl aromatic protons H d and H e (Dd = 0.18 ppm, Figure 2a,c and Figures S6.1-S6.3), indicative of intermolecular p-p aromatic stacking interactions between fullerene guest and aromatic belt of the PBPB macrocyclic host. [32] This was supported by upfield shifts of the fullerene resonances in the 13 CNMR spectrum, consistent with a ring currente ffect from the diamagnetica romatic system of the macrocycle (Figures 2b,c,S 6.9, and S6.10). [33] By contrast, the thiophene proton shift is much less pronounced (Dd H h = 0.02-0.05 ppm) sincet hese protons are positioned outside the cavity in order to direct the Lewis basic sulfur lone pairs towards the fullerene (Figure 2c).…”

DLPNO-CCSD(T) scaled methods for the accurate treatment of large supramolecular complexes

“…In the field of materials science, for instance, different electron‐acceptor nanoforms of carbon, namely fullerenes, carbon nanotubes, and graphene, have been successfully combined by means of NCIs with electron‐donor systems to form donor–acceptor (D–A) supramolecular complexes . Experimental studies on these D–A supramolecular complexes are of great relevance to gain insight into the fundamental and omnipresent photoinduced electron‐transfer process, which is required, for example, in organic photovoltaic applications …”

“…D–A supramolecular structures with significant contribution of CH–π contacts have been proposed as the most stable structures for the truxTTF•C 30 H 12 associates . Experimental 1 H‐NMR evidences recently reported on similar truxTTF supramolecular complexes with corannulene‐based buckybowls C 32 H 12 and C 38 H 14 point toward the formation of staggered associates dominated by CH–π interactions as the preferred arrangements . Nevertheless, interaction energy calculations using high‐level ab initio methods that support these supramolecular arrangements dominated by CH–π interactions have not been performed yet.…”

Functionalized Truxene Scaffold: A Promising Advanced Organic Material for Digital Era

“…From the last two decades, various efforts have been carried out towards the design, synthesis, and physical properties of some interesting polycyclic aromatic hydrocarbons (PAHs) due to their unique optoelectronic and thermal properties. Among various π‐conjugated PAHs viz truxene, fullerene (C 60 ), coronene, and sumanene (Figure ), the truxene scaffold having C 3v point group is considered as a promising material in the field of bio‐inorganic, medicinal chemistry, material, and environmental sciences. Due to the existence of interesting features viz C 3 ‐symmetry, strong blue emission, and rigid planar structure, the truxene framework has become a valuable and highly attractive building block for the generation of diverse novel materials with interesting applications in different areas of science and technology.…”