Supramolecular Structures and Photoelectronic Properties of the Inclusion Complex of a Cyclic Free‐Base Porphyrin Dimer and C₆₀

Abstract

A cyclic free-base porphyrin dimer H4-CPD(Py) (CPD = cyclic porphyrin dimer) linked by butadiyne moieties bearing 4-pyridyl groups self-assembles to form a novel porphyrin nanotube in the crystalline state. The cyclic molecules link together through nonclassical C-H⋅⋅⋅N hydrogen bonds and π–π interactions of the pyridyl groups along the crystallographic a axis. H4-CPD(Py) includes a C60 molecule in its cavity in solution. In the crystal structure of the inclusion complex (C60⊂H4-CPD(Py)), the dimer “bites” a C60 molecule by tilting the porphyrin rings with respect to each other, and there are strong π–π interactions between the porphyrin rings and C60. The included C60 molecules form a zigzag chain along the crystallographic b axis through van der Waals contacts with each other. Femtosecond laser flash photolysis of C60⊂H4-CPD(Py) in the solid state with photoexcitation at 420 nm shows the formation of a completely charge-separated state {H4-CPD(Py)·+ + C60·−}, which decays with a lifetime of 470 ps to the ground state. The charge-carrier mobility of the single crystal of C60⊂H4-CPD(Py) was determined by flash photolysis time-resolved microwave conductivity (FP-TRMC) measurements. C60⊂H4-CPD(Py) has an anisotropic charge mobility (Σμ = 0.16 and 0.13 cm2 V(−1) s(−1)) along the zigzag chain of C60 (which runs at 45° and parallel to the crystallographic b axis). To construct a photoelectrochemical cell, C60⊂H4-CPD(Py) was deposited onto nanostructured SnO2 films on a transparent electrode. The solar cell exhibited photovoltaic activity with an incident photon to current conversion efficiency of 17%.

Synthesis of ordered carbonaceous frameworks from organic crystals

“…1a. The thermal behaviour of Ni 2 -CPD Py was investigated and compared to the corresponding free base porphyrin (H 4 -CPD Py ) 25 . Figure 1b displays weight changes of Ni 2 -CPD Py and H 4 -CPD Py measured by thermogravimetry (TG) in N 2 and their differential scanning calorimetry (DSC) curves.…”

Solvent‐Polarity‐Tunable Dimeric Association of a Fullerene (C60)–N,N‐Dimethylaminoazobenzene Dyad: Modulated Electronic Coupling of the Azo Chromophore with a Substituted 3D Fullerene

“…In the present investigation, the obtained packing pattern of DPNME belongs to a rare class; unlike the porphyrin [118][119][120][121] or phthalocyanine [122] bowl-shaped electron donors, the linear geometry of the AZNME donor part of DPNME along with the dominant fullerene-fullerene intermolecular p-p interactions have brought about structural transformations. The geometrical constraints imposed by rigid C 60 on the dyad framework could contribute substantially towards the resultant dyad arrays.…”

Wraparound Hosts for Fullerenes: Tailored Macrocycles and Cages

“…Their studies focus on the self-assembly of macrocyclic dimers 33 and 34 (Figure 12). [49][50][51] Thanks to the pyridyl-substituted porphyrin units and to the rigidity of these molecules, an original network of CÀ H···N hydrogen bonds between the pyrrole b-hydrogen atoms and the pyridyl nitrogen atoms as well was p-p interactions between adjacent pyridyl rings is formed, thus allowing the growth of supramolecular nanotubes. In the case of 34, this arrangement is maintained when C 60 is cocrystallized with the host.…”

“…A very different situation arises when C 60 and 37 are cocrystallized. [51] Indeed, nanotubes are no longer observed in the solid state, and fullerenes are organized in a zig-zag fashion. This structural modification consequently results in a decreased conductivity (0.13-0.16 cm 2 V À1 s À1 ) and a lower anisotropy.…”