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A three-fold symmetric trioxotriangulene derivative with three pyridyl groups as coordinating sites was designed and synthesized. In a cyclic voltammetry measurement, the trioxotriangulene skeleton exhibited a multi-stage redox ability from neutral radical to radical tetra-anion species. In the zinc complex of monoanion species, three pyridyl groups coordinated to the zinc ion to build up a two-dimensional coordination network with a cavity larger than 12 &Aring, in diameter. This complex was utilized as a cathode active material of a lithium ion battery, and it exhibited a capacity of ca. 60 mAh g&minus, 1 per the weight of the active material with a stable cycling performance up to 1000 cycles. This work shows that the coordination network formed by the trioxotriangulene-based ligand was effective in the improvement of cycle performance of the organic rechargeable battery.

Despite recent advances in the carbonization of organic crystalline solids like metal-organic frameworks or supramolecular frameworks, it has been challenging to convert crystalline organic solids into ordered carbonaceous frameworks. Herein, we report a route to attaining such ordered frameworks via the carbonization of an organic crystal of a Ni-containing cyclic porphyrin dimer (Ni2-CPDPy). This dimer comprises two Ni–porphyrins linked by two butadiyne (diacetylene) moieties through phenyl groups. The Ni2-CPDPy crystal is thermally converted into a crystalline covalent-organic framework at 581 K and is further converted into ordered carbonaceous frameworks equipped with electrical conductivity by subsequent carbonization at 873–1073 K. In addition, the porphyrin’s Ni–N4 unit is also well retained and embedded in the final framework. The resulting ordered carbonaceous frameworks exhibit an intermediate structure, between organic-based frameworks and carbon materials, with advantageous electrocatalysis. This principle enables the chemical molecular-level structural design of three-dimensional carbonaceous frameworks., Carbon-based materials are promising alternatives to noble metal catalysts, but their structures are typically disordered and difficult to control. Here, the authors obtain ordered carbonaceous frameworks with advantageous electrocatalytic properties via the carbonization of nickel-containing porphyrin dimer networks.

Free-bases and a nickel(II) complex of phenothiazine-bridged cyclic porphyrin dimers bearing self-assembling 4-pyridyl groups (M2-Ptz-CPDPy(OCn); M = H2 or Ni, OCn = OC6 or OC3) at opposite meso-positions have been prepared as host molecules for fullerenes. The free-base dimer (H4-Ptz-CPDPy(OC6)) includes fullerenes with remarkably high association constants such as 3.9 ± 0.7 × 10(6) M(-1) for C60 and 7.4 ± 0.8 × 10(7) M(-1) for C70 in toluene. This C60 affinity is the highest value ever among reported receptors composed of free-base porphyrins. The nickel dimer (Ni2-Ptz-CPDPy(OC6)) also shows high affinities for C60 (1.3 ± 0.2 × 10(6) M(-1)) and C70 (over 10(7) M(-1)). In the crystal structure of the inclusion complex of C60 within H4-Ptz-CPDpy(OC3), the C60 molecule is located just above the centers of the porphyrins. The two porphyrin planes are almost parallel to each other and the center-to-center distance (12.454 Å) is close to the optimal separation (∼12.5 Å) for C60 inclusion. The cyclic porphyrin dimer forms a nanotube through its self-assembly induced by C-H···N hydrogen bonds between porphyrin β-CH groups and pyridyl nitrogens as well as π-π interactions of the pyridyl groups. The C60 molecules are linearly arranged in the inner channel of this nanotube.

We have studied the supramolecular structures and photoelectronic properties of inclusion complexes of cyclic porphyrin dimers (M2-CPDPy, M = Ni, 2H) and fullerenes (C60, C70, PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) and Li+@C60). The porphyrin dimers have self-assembling 4-pyridyl groups at the meso positions and include fullerenes in their cavities with high affinities (Kassoc ≈ 105M−1). In crystals, C60 ⊂ Ni2-CPDPy and PCBM ⊂ Ni2-CPDPy give self-assembled porphyrin nanotubes containing the linear arrays of fullerene molecules. These self-assemblies are induced mainly by the non-classical hydrogen bonds between pyridyl nitrogens and porphyin β C–H groups. On the other hand, in the crystals of C60 ⊂ H4-CPDPy and C70 ⊂ H4-CPDPy, the included fullerene molecules show zigzag chains through van der Waals contacts with each other. Due to these well-ordered arrays of C60, both crystals of C60⊂ Ni2-CPDPy and C60 ⊂ H4-CPDPy have high charge mobilities (Σμ > 0.1 cm2 V−1 s−1). C60 ⊂ H4-CPDPy shows photoinduced electron transfer from the porphyrin moieties to C60 and photovoltaic activity with IPCEmax = 17% in photoelectrochemical cells. Moreover, the inclusion complexes of lithium-ion-encapsulated C60(Li+@C60) and M2-CPDPy exhibit photoinduced charge separation with very long lifetimes reaching submillisecond order. [TANSO 2013 (No. 260) 284–91.]

Cyclic nickel and free-base porphyrin dimers (Ni2-CPDPy and H4-CPDPy) include [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) both in solution and in the crystals. In the crystal packing of the i...

A cyclic free-base porphyrin dimer H 4 -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 non-classical C―H···N hydrogen bonds and π―π interactions of the pyridyl groups along the crystallographic a axis. H 4 -CPD Py includes a C 60 molecule in its cavity in solution. In the crystal structure of the inclusion complex (C 60 ⊂H 4 -CPD Py ), the dimer "bites" a C 60 molecule by tilting the porphyrin rings with respect to each other, and there are strong π―π interactions between the porphyrin rings and C 60 . The included C 60 molecules form a zigzag chain along the crystallographic b axis through van der Waals contacts with each other. Femtosecond laser flash photolysis of C 60 ⊂H 4 -CPD Py in the solid state with photoexcitation at 420 nm shows the formation of a completely charge-separated state {H 4 -CPD Py •+ + C 60 •― }, which decays with a lifetime of 470 ps to the ground state. The charge-carrier mobility of the single crystal of C 60 ⊂H 4 -CPD Py was determined by flash photolysis time-resolved microwave conductivity (FP-TRMC) measurements. C 60 ⊂H 4 -CPD Py has an anisotropic charge mobility (Σμ=0.16 and 0.13 cm 2 V ―1 s ―1 ) along the zigzag chain of C 60 (which runs at 45° and parallel to the crystallographic b axis). To construct a photoelectrochemical cell, C 60 ⊂H 4 -CPD Py was deposited onto nanostructured SnO 2 films on a transparent electrode. The solar cell exhibited photovoltaic activity with an incident photon to current conversion efficiency of 17 %.

A cyclic porphyrin dimer (Ni2−CPDPy) linked by butadiyne moieties bearing 4-pyridyl groups includes a C60 molecule inside its cavity in solution to give a 1:1 inclusion complex (C60⊂Ni2−CPDPy). The charge-transfer (CT) band is observed at 645 nm in the UV−vis absorption spectrum of the solution of C60⊂Ni2−CPDPy. In the cyclic voltammogram of C60⊂Ni2−CPDPy, a small anodic shift of the porphyrin oxidation potential and a small cathodic shift of the fullerene reduction potential compared with their original redox potentials are indicative of CT interaction from the porphyrin to C60. In the crystal structure of C60⊂Ni2−CPDPy, a porphyrin nanotube is formed by the self-assembly of Ni2−CPDPy. Ni2−CPDPy molecules link together through nonclassical C−H···N hydrogen bonds and π−π interactions of the pyridyl groups along the crystallographic b axis. The included C60 molecules are linearly arranged in the nanotube to afford a supramolecular peapod. The charge-carrier mobility of the single crystal of C60⊂Ni2−CPDPy w...

We have prepared nickel complexes and freebases of cyclic porphyrin dimers linked by butadiyne or phenothiazine groups. The porphyrin dimers have self-assembling pyridyl groups at the opposite meso positions and include fullerenes such as C60, PCBM, C70, and Li+@C60 to give π-complexes. In particular, the phenothiazine-bridged cyclic porphyrin dimers exhibit notable high affinities toward C60 (Kassoc > 106 M−1) and C70 (Kassoc > 107 M−1). In the crystal structures, the π-complexes of C60 and PCBM within the butadiyne-bridged nickel dimer and the phenothiazine-bridged freebase dimer afford self-assembled porphyrin nanotubes containing the linear arrays of the fullerenes. These self-assemblies are formed by the C-H · · · N hydrogen bonds and π-π interactions of the meso pyridyl groups. On the other hand, the π-complexes of C60 and C70 within the butadiyne-bridged freebase dimer gave the zigzag chains of the fullerenes through van der Waals contacts with each fullerene. These well-ordered C60 arrays yield high electron mobilities (Σμ > 10−1 cm2V−1 s−1). The π-complexes of C60 and Li+@C60 within the butadiyne-bridged dimers perform photoinduced electron transfer from the porphyrins to the fullerenes to give the CS states. The π-complexes of Li+@C60 with the butadiyne-bridged dimers afford the CS states of remarkably long lifetimes reaching submillisecond order.

Lithium ion encapsulated [60]fullerene (Li+@C60) is included within a free base and nickel complex of a cyclic porphyrin dimer (M-CPDPy, M = H4 and Ni2) to afford supramolecules (Li+@C60⊂M-CPDPy) in a polar solvent (benzonitrile) with the association constants of 2.6 × 105 M−1 and 3.5 × 105 M−1, respectively. From the electrochemical analysis, the energies of the charge-separated (CS) states are estimated to be 1.07 eV for Li+@C60⊂H4-CPDPy and 1.20 eV for Li+@C60⊂Ni2-CPDPy. Both values are lower than the triplet excited energies of the fullerene and porphyrin. Upon the photoexcitation at the Q-band of the porphyrin chromophore of Li+@C60⊂H4-CPDPy, electron transfer from the triplet excited state of the free base porphyrin to Li+@C60 occurs to produce the CS state. Li+@C60⊂Ni2-CPDPy also undergoes photoinduced electron transfer to produce the CS state. The lifetimes of the resulting CS states are 0.50 ms for Li+@C60⊂H4-CPDPy and 0.67 ms for Li+@C60⊂Ni2-CPDPy. These remarkably long CS lifetimes are the best values ever reported for non-covalent porphyrin-fullerene supramolecules in solution and are attributable to the lower CS energies than the triplet energy of each chromophore.

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