We synthesized a two-dimensional (2D) crystalline covalent organic framework (spc-COF) that was designed to be fully π-conjugated and constructed from all sp carbons by C=C condensation reactions of tetrakis(4-formylphenyl)pyrene and 1,4-phenylenediacetonitrile. The C=C linkages topologically connect pyrene knots at regular intervals into a 2D lattice with π conjugations extended along both and directions and develop an eclipsed layer framework rather than the more conventionally obtained disordered structures. The spc-COF is a semiconductor with a discrete band gap of 1.9 electron volts and can be chemically oxidized to enhance conductivity by 12 orders of magnitude. The generated radicals are confined on the pyrene knots, enabling the formation of a paramagnetic carbon structure with high spin density. The sp carbon framework induces ferromagnetic phase transition to develop spin-spin coherence and align spins unidirectionally across the material.

The spatial charge arrangement of a typical quasi-two-dimensional organic conductor α-(BEDT-TTF) 2 I 3 is revealed by single crystal structure analysis using synchrotron radiation. The results show that the horizontal stripe type structure, which was suggested by mean field theory, is established. We also find the charge disproportion above the metal-insulator transition temperature and a significant change in transfer integrals caused by the phase transition. Our result elucidates the insulating phase of this material as a 2k F charge density localization.KEYWORDS: α-(BEDT-TTF)2I3, Charge Ordering, Quasi two dimensional organic conductor, Synchrotron Radiation, Crystal structure analysisAs an origin of a metal-insulator (M-I) transition, the charge ordering caused by the long rangeCoulomb interaction between electrons is a prominent phenomenon as well as the Peierls transition or the Mott Hubbard transition. Organic materials having low-dimensionality provide us a field of studying such interesting phenomena. 1 Among them, an organic conductor α-(BEDT-TTF) 2 I 3 , which undergoes a M-I transition at T M I = 135 K, 2 attracts considerable attention because of its possibility of zero-gap semiconductor under hydrostatic pressures. 3 The insulating phase is a nonmagnetic state with a spin gap, 4 and interpreted to be caused by a charge disproportionation theoretically 5, 6 and experimentally. 7,8 According to these studies, horizontal-charge stripes with valences of +1e and 0 are expected on BEDT-TTF molecules while no structural evidence has been reported. In this letter, we report a precise structure of α-(BEDT-TTF) 2 I 3 as a function of temperature based on synchrotron radiation diffraction measurements in order to provide evidence of the charge disproportionation.α-(BEDT-TTF) 2 I 3 , which has a two-dimensional (2D) conduction band, is a typical organic conductor made of I − 3 ions and BEDT-TTF 0.5+ on average. The crystal structure of this material is a sandwich structure of I 3 insulating layers and 2D-BEDT-TTF conduction layers having a quarterfilled hole band. The space group at room temperature is P1. Together with the metal-insulator transition, it shows paramagnetic-nonmagnetic transition. 4 According to several reports, 6, 9, 10 this transition is not a Peierls transition but a charge ordering caused by a strong Coulomb repulsion.

Ordered one-dimensional open channels represent the typical porous structure of two-dimensional covalent organic frameworks (COFs). Here we report a general synthetic strategy for converting these open lattice structures into ordered donor-acceptor heterojunctions. A three-component topological design scheme was explored to prepare electron-donating intermediate COFs, which upon click reaction were transformed to photoelectric COFs with segregated donor-acceptor alignments, whereas electron-accepting buckyballs were spatially confined within the nanochannels via covalent anchoring on the channel walls. The donor-acceptor heterojunctions trigger photoinduced electron transfer and allow charge separation with radical species delocalized in the π-arrays, whereas the charge separation efficiency was dependent on the buckyball content. This new donor-acceptor strategy explores both skeletons and pores of COFs for charge separation and photoenergy conversion.

Members of the epidermal growth factor (EGF) family are the most important growth factors involved in epithelialization during cutaneous wound healing. Heparin-binding EGF-like growth factor (HB-EGF), a member of the EGF family, is thought to play an important role in skin wound healing. To investigate the in vivo function of HB-EGF in skin wound healing, we generated keratinocyte-specific HB-EGF-deficient mice using Cre/loxP technology in combination with the keratin 5 promoter. Studies of wound healing revealed that wound closure was markedly impaired in keratinocyte-specific HB-EGF-deficient mice. HB-EGF mRNA was upregulated at the migrating epidermal edge, although cell growth was not altered. Of the members of the EGF family, HB-EGF mRNA expression was induced the most rapidly and dramatically as a result of scraping in vitro. Combined, these findings clearly demonstrate, for the first time, that HB-EGF is the predominant growth factor involved in epithelialization in skin wound healing in vivo and that it functions by accelerating keratinocyte migration, rather than proliferation.

By developing metallophthalocyanines and diimides as electron-donating and -accepting building blocks, herein, we report the construction of new electron donor-acceptor covalent organic frameworks (COFs) with periodically ordered electron donor and acceptor π-columnar arrays via direct polycondensation reactions. X-ray diffraction measurements in conjunction with structural simulations resolved that the resulting frameworks consist of metallophthalocyanine and diimide columns, which are ordered in a segregated yet bicontinuous manner to form built-in periodic π-arrays. In the frameworks, each metallophthalocyanine donor and diimide acceptor units are exactly linked and interfaced, leading to the generation of superheterojunctions-a new type of heterojunction machinery, for photoinduced electron transfer and charge separation. We show that this polycondensation method is widely applicable to various metallophthalocyanines and diimides as demonstrated by the combination of copper, nickel, and zinc phthalocyanine donors with pyrommellitic diimide, naphthalene diimide, and perylene diimide acceptors. By using time-resolved transient absorption spectroscopy and electron spin resonance, we demonstrated that the COFs enable long-lived charge separation, whereas the metal species, the class of acceptors, and the local geometry between donor and acceptor units play roles in determining the photochemical dynamics. The results provide insights into photoelectric COFs and demonstrate their enormous potential for charge separation and photoenergy conversions.

Light works: Mechanistic insights into the photochemical events and charge dynamics of a donor–acceptor covalent organic framework were given by time‐resolved transient absorption spectroscopy and time‐resolved electron spin resonance spectroscopy (see picture). The organic framework triggers ultrafast electron transfer and enables long‐distance charge delocalization and exceptional long‐term charge separation.

The velocity field of the M87 jet from milli-arcsecond (mas) to arcsecond scales is extensively investigated together with new radio images taken by EVN observations. We detected proper motions of components located at between 160 mas from the core and the HST-1 complex for the first time. Newly derived velocity fields exhibits a systematic increase from sub-to-superluminal speed in the upstream of HST-1. If we assume that the observed velocities reflect the bulk flow, we here suggest that the M87 jet may be gradually accelerated through a distance of 10 6 times of the Schwarzschild radius of the supermassive black hole. The acceleration zone is co-spatial with the jet parabolic region, which is interpreted as the collimation zone of the jet (Asada & Nakamura). The acceleration and collimation take place simultaneously, which we suggest a characteristic of magnetohydrodynamic flows. Distribution of the velocity field has a peak at HST-1, which is considered as the site of overcollimation, and shows a deceleration downstream of HST-1 where the jet is conical. Our interpretation of the velocity map in the M87 jet gives a hypothesis in AGNs that the acceleration and collimation zone of relativistic jets extends over the whole scale within the sphere of influence of the supermassive black hole.

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