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Tetranuclear [Cu3Ln] complexes (Ln = Gd(iii), Tb(iii), and Dy(iii)) with a planar tetranuclear structure were synthesized. The [Cu3Gd] complex has an ST = 5 spin ground state and the [Cu3Tb] and [Cu3Dy] complexes show slow magnetic relaxation.

A series of trinuclear complexes, [MnII2YIII(L)2(HL)2(NO3)3][YIII(NO3)5]·7H2O (1'), [MnII2GdIII(HL)4(NO3)4]2[MnII2GdIII(L)(HL)3(NO3)4][GdIII(NO3)5]4·2(o-Xy)·12H2O (2') and [MnII3(L)(HL)2(NO3)4](NO3)·1.25(p-Xy) (3'), were synthesized by using a β-diketone ligand HL (HL = 1,3-bis(pyridin-2-yl)propane-1,3-dione). X-ray structural analyses revealed each complex has a trinuclear core with a Mn(II)-M-Mn(II) arrangement (M = YII (1), GdIII (2), and MnII (3)). In 1' with a diamagnetic Y(III) ion, negligible antiferromagnetic interactions between terminal Mn(II) ions are operative. On the other hand, 2' shows ferromagnetic interactions between Mn(II) and Gd(III) ions, affording spin ground state of ST = 17/2. The homometallic Mn(II)3 complex of 3' has ST = 5/2 spin ground state resulting from the antiferromagnetic interactions between neighboring Mn(II) ions. Maximum magnetic entropy change (-ΔSm) of 1' - 3' was estimated to be 12.3, 24.8, and 8.0 J kg-1 K-1, respectively.

Spatial distance is an important factor in controlling the functional interactions between molecular units in a conjugate; therefore, the bridging unit has been closely examined. Here, we examined the effect of the flexibility of bridging alkyl chains on the proximity of stacked porphyrin and phthalocyanine conjugated with a fourfold rotaxane linkage. We found that closely stacking two π systems requires bridging alkyl chains above a certain length, and the shorter bridges hinder stacking because of their lower flexibility. The stacking distance between porphyrin and phthalocyanine in the conjugate with decyl (C

Herein, we report that the close-stacking of a double-decker-type dinuclear iron phthalocyanine complex on a graphite surface is effective for achieving high methane oxidation activity, comparable to those of certain MMOs, in an aqueous solution.

Development of supramolecular methods to further activate a highly reactive intermediate is a fascinating strategy to create novel potent catalysts for activation of inert chemicals. Herein, a supramolecular approach to enhance the oxidizing ability of a high-valent oxo species of a nitrido-bridged iron porphyrinoid dimer that is a known potent molecular catalyst for light alkane oxidation is reported. For this purpose, a nitrido-bridged dinuclear iron complex of porphyrin-phthalocyanine heterodimer 35+ , which is connected through a fourfold rotaxane, was prepared. Heterodimer 35+ catalyzed ethane oxidation in the presence of H2 O2 at a relatively low temperature. The site-selective complexation of 35+ with an additional anionic porphyrin (TPPS4- ) through π-π stacking and electrostatic interactions afforded a stable 1:1 complex. It was demonstrated that the supramolecular post-synthetic modification of 35+ enhances its catalytic activity efficiently. Moreover, supramolecular conjugates achieved higher catalytic ethane oxidation activity than nitrido-bridged iron phthalocyanine dimer, which is the most potent iron-oxo-based molecular catalyst for light-alkane oxidation reported so far. Electrochemical measurements proved that the electronic perturbation from TPPS4- to 35+ enhanced the catalytic activity.

Tooth formation is accomplished under strict genetic programs. Although patients with chromosome 12q14 aberration shows tooth phenotype including the size and eruption timing with bone growth anomaly, its etiology is uncertain. Here, we examined expression of Hmga2, which is encoded at chromosome 12q14, in mouse tooth germs and analyzed the involvement in lower first molar (M1) and mandibular bone development. Hmga2 expression was immunohistochemically detected at enamel organ and the surrounding mesenchyme of the M1 germs. The expression was dynamically changed with gestation and rapidly decreased in postnatal mice. In Hmga2-/- mice, the M1 germs and crowns were diminished in size, and formation and eruption of molars were delayed with mandibular bone growth retardation. Hmga2 cDNA or siRNA transfection showed that Hmga2 transcriptionally up-regulates expression of stem cell factors, Sox2 and Nanog. They were co-localized with Hmga2 in the germs, but differentially distributed at enamel organ and mesenchyme in Hmga2-/- mice. These results demonstrate that Hmga2 expressed in tooth germs regulates the growth, sizing and eruption and stem cell factor expression in different compartment of the germ and associates with mandibular bone growth. Although future studies are needed, the present study demonstrates HMGA2 regulation of tooth genesis with skeletal development.

Catalytic methane oxidation was conducted using a μ-nitrido-bridged dinuclear iron complex of a four-fold rotaxane heterodimer of a porphyrin and a phthalocyanine. Extension of the π-stacked structure of the four-fold rotaxane-based μ-nitrido-bridged iron porphyrinoid dimer by supramolecular complexation with an additional tetraanionic porphyrin apparently increased the methane conversion ability.

Loss of mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) expression closely associates with increased aggressive behaviors of oral carcinoma cells. It emphasizes that a mechanism to suppress the expression is an important subject for understanding carcinoma progression pathway. However, nothing is known at present. This study conducted on transcriptional regulation of the gene down-regulation. Reporter assays showed the presence of the silencer region between +402 and +501 region of MALT1 gene in oral carcinoma cells. It encoded a binding site of nuclear factor-κB subunit, RELA. RELA binding to the site was confirmed by the chromatin immunoprecipitation analyses, and deletion and mutations of the site significantly decreased the RELA binding. Short interfering RNAs for RELA up-regulated reporter gene and endogenous MALT1 protein expressions, and deletion and mutations of RELA binding site increased reporter gene expression. These results demonstrated RELA-binding to the site suppresses MALT1 expression that may facilitate oral carcinoma progression.

Cofacial dimers of porphyrin and/or phthalocyanine are plausible frameworks for functional molecular systems such as molecular catalysts and molecular memories. We recently developed a supramolecular array of a porphyrin and phthalocyanine linked by a four-fold rotaxane. In this study, we demonstrated programmable hetero-ion arrangement in the heterodimer of these tetrapyrrolic ligands. Ni(II) and Fe(II) ions showed kinetically selective binding to the porphyrin, whereas Mn(II) ions selectively bound to the phthalocyanine, in the supramolecular array. After the first metal complexation, subsequent metal insertion into the vacant ligand afforded the programmed heterodinuclear complex. Moreover, the metal arrays were extended to heterotrinuclear complexes via ionic pairing of the cationic four-fold rotaxane with a tetraanionic metalloporphyrin.

The redox potential of a supramolecular porphyrin-phthalocyanine heterodimer was perturbed by the stacking of an extra metalloporphyrin to the phthalocyanine. This stacking gave rise to π-π and electrostatic interactions between the tetracationic dimer and the tetraanionic metalloporphyrin, with a Au(iii) metalloporphyrin exhibiting a larger effect than Cu(ii) and Pd(ii) complexes among square planar complexes.

Cofacial assemblies of metalloporphyrinoids represent a fascinating platform for the fabrication of novel functional molecular assemblies based on π–π, d–d, and d–π interactions between components. In this paper, we present a novel synthetic strategy for the programmable arrangement of different metal ions inside a cofacially stacked trimer of porphyrinoids. A combination of two different assemblies was utilized for our purpose: a tetracationic fourfold rotaxane heterodimer between a porphyrin with four alkylammonium chains and a phthalocyanine bearing four peripheral crown ethers, and a stacked assembly between the fourfold rotaxane heterodimer and an additional tetraanionic porphyrin. Three metal ions, namely Cu(II), Ag(II), and Au(III), were arranged inside the cofacially stacked assembly of three porphyrinoids. Moreover, paramagnetic Cu(II) ions were arranged inside a cofacially stacked heterotrimer of porphyrinoids and were precisely programmed, affording the desired spin–spin communications as readable information. These results indicated that the developed strategy is effective for arranging various metal ions in cofacially stacked assemblies of porphyrinoids toward the creation of molecular tags or bar codes.

Single-crystal X-ray structures of stacked ionic assemblies of meso-tetrakis(N-alkylpyridinium-4-yl)porphyrin and meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4−) were revealed. The tetracationic...

Recently, we reported synthesis of porphyrin/phthalocyanine conjugates linked by fourfold rotaxane. In the conjugate, a porphyrin and a phthalocyanine formed a heterodimer in a cofacial fashion (Fig. 1a). [1] The conjugate is a promising platform for supramolecular catalysts based on dinuclear porphyrinoid complexes, because various metal ions to be a functional center are able to be arrayed in the conjugate regioselectively to afford homo- and hetero-dinuclear centers in the conjugate. [2,3] Moreover, these arrays were expanded to hetero-trinuclear arrays (Fig. 1b). [3-6] In this paper, we will present regioselective metal arraying in the conjugate and the supramolecular catalytic functions (Fig. 2). One of the methods to prepare the hetero-dinuclear complexes was to use the difference of metalation rate between porphyrin and phthalocyanine. We found reaction conditions for porphyrin-selective Fe(II) or Ni(II) insertion and phthalocyanine-selective Mn(II) insertion. Subsequent metalation to another porphyrinoid in the conjugate gave a hetero-dinuclear complex. We used these multinuclear complexes in the conjugate as catalysts. The dinuclear iron complex exhibited good catalytic activity in electrochemical reduction of molecular oxygen to water. [7] References: 1) Y. Yamada, M. Okamoto, K. Furukawa, T. Kato, and K. Tanaka., Angew. Chem. Int. Ed., 51, 709 (2012,). 2) Y. Yamada, N. Mihara, and K. Tanaka., Dalton Trans., 42, 15873 (2013). 3) N. Mihara, Y. Yamada, and K. Tanaka., submitted. 4) Y. Yamada, N. Mihara, S. Shibano, K. Sugimoto, and K. Tanaka., J. Am.Chem. Soc., 135, 11505 (2013). 5) Y. Yamada, S. Akine, K. Sugimoto, and K. Tanaka, Chem. Euro. J., 22, 12371 (2016). 6) N. Mihara, Y. Yamada, S. Akine, K. Sugimoto, and K. Tanaka., submitted. 7) N. Mihara, Y. Yamada, and K. Tanaka., submitted. Figure 1

We report the preparation and crystal structure of a triply stacked metal complex array in which a Cu-phthalocyanine is sandwiched between different Cu-porphyrins. The discrete heterogeneous assembly was prepared through formation of a fourfold rotaxane from a tetradactyl porphyrin with alkylammonium moieties and a phthalocyanine bearing four crown ethers and the subsequent formation of an ionic complex between the fourfold rotaxane and a tetraanionic porphyrin. The tetraanionic porphyrin, Cu-TPPS(4-), is selectively bound to the fourfold rotaxane through cooperative π-π and ionic interactions. The crystal structure revealed the columnar stacked array of the three planar building components in a precise order and spatial arrangement that promote intermolecular electronic communication.

We report synthesis of a hetero-dinuclear metal complex in a four-fold rotaxane, in which a Cu(2+)-porphyrin and a Zn(2+)-phthalocyanine are cofacially stacked. Interaction between the two metal complexes in the rotaxane was investigated by a UV-Vis absorption spectral study.