Pyridinic Nitrogen Modification for Selective Acetylenic Homocoupling on Au(111).

On-surface acetylenic homocoupling has been proposed to construct carbon nanostructures featuring sp hybridization. However, the efficiency of linear acetylenic coupling is far from satisfactory, often resulting in undesired enyne products or cyclotrimerization products due to the lack of strategies to enhance chemical selectivity. Herein, we inspect the acetylenic homocoupling reaction of polarized terminal alkynes (TAs) on Au(111) with bond-resolved scanning probe microscopy. The replacement of benzene with pyridine moieties significantly prohibits the cyclotrimerization pathway and facilitates the linear coupling to produce well-aligned N-doped graphdiyne nanowires. Combined with density functional theory calculations, we reveal that the pyridinic nitrogen modification substantially differentiates the coupling motifs at the initial C-C coupling stage (head-to-head vs head-to-tail), which is decisive for the preference of linear coupling over cyclotrimerization.

Intra- and Inter-Self-Assembly of Identical Supramolecules on Silver Surfaces.

Self-assembly of identical organometallic supramolecules into ordered superstructures is of great interest in both chemical science and nanotechnology due to its potential to generate neoteric properties through collective effects. In this work, we demonstrate that large-scale self-organization of atomically precise organometallic supramolecules can be achieved through cascaded on-surface chemical reactions, by the combination of intra- and inter-supramolecular interactions. Supramolecules with defined size and shape are first built through intramolecular reaction and intermolecular metal coordination, followed by the formation of well-ordered two-dimensional arrays with the assistance of Br atoms by -C-H···Br interactions. The mechanism of this process has been investigated from the perspectives of thermodynamics and kinetics.

On-Surface Debromination of 2,3-Bis(dibromomethyl)- and 2,3-Bis(bromomethyl)naphthalene: Dimerization or Polymerization?

We describe the on-surface dehalogenative homocoupling of benzylic bromides, namely bis-bromomethyl- and bis-gem-(dibromomethyl) naphthalene as a potential route to either hydrocarbon dimers or conjugated polymers on Au(111). While bis-gem-(dibromomethyl) naphthalene affords different dimers with naphthocyclobutadiene as the key intermediate, bis-bromomethyl naphthalene furnishes a poly(o-naphthylene vinylidene) as a non-conjugated polymer which undergoes dehydrogenation toward its conjugated derivative poly(o-naphthylene vinylene) upon mild annealing. A combination of scanning tunneling microscopy, non-contact atomic force microscopy and density functional theory calculations provides deep insights into the prevailing mechanisms.

Converting n-Alkanol to Conjugated Polyenal on Cu(110) Surface at Mild Temperature.

Achieving C(sp3)-H activation at a mild temperature is of great importance from both scientific and technologic points of view. Herein, on the basis of the on-surface synthesis strategy, we report the significant reduction of the C(sp3)-H activation barrier, which results in the full C(sp3)-H to C(sp2)-H transformation of n-alkanol (octacosan-1-ol) at a mild temperature as low as 350 K on the Cu(110) surface, yielding the conjugated polyenal (octacosa-tridecaenal) as the final product. The reaction mechanism is revealed by the combined scanning tunneling microscope, density functional theory, and synchrotron radiation photoemission spectroscopy.

Direct transformation of n-alkane into all-trans conjugated polyene via cascade dehydrogenation.

Selective C(sp3) -H activation is of fundamental importance in processing alkane feedstocks to produce high-value-added chemical products. By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of n-alkane molecules under surface constraints, which yields monodispersed all-trans conjugated polyenes with unprecedented length controllability. We are also able to demonstrate the generality of this concept for alkyl-substituted molecules with programmable lengths and diverse functionalities, and more importantly its promising potential in molecular wiring.

Constructing and Transferring Two-Dimensional Tessellation Kagome Lattices via Chemical Reactions on Cu(111) Surface.

Two-dimensional (2D) tessellation of organic species acquired increased interests recently because of their potential applications in physics, biology, and chemistry. 2D tessellations have been successfully constructed on surfaces via various intermolecular interactions. However, the transformation between 2D tessellation lattices has been rarely reported. Herein, we successfully fabricated two types of Kagome lattices on Cu(111). The former phase exhibits (3,6,3,6) Kagome lattices, which are stabilized via the intermolecular hydrogen bond interactions. The latter phase is formed through direct chemical transferring from the former one maintaining almost the same Kagome lattices, except for that the unit cell rotates for 4°. Detailed scanning tunneling microscopy and density functional calculation studies reveal that the chemical transformation is achieved by the formation of the N-Cu-N metal-organic bonds via dehydrogenation reactions of the amines.

[Clinical application of modified skin soft tissue expansion in early repair of devastating wound on the head due to electrical burn].

OBJECTIVE: To observe the clinical effect of modified skin soft tissue expansion in repair of devastating wound on the head due to electrical burn in the early stage. METHODS: Twenty-one patients with partial scalp soft tissue defect accompanying skull exposure and necrosis in different degree due to high-voltage electrical burn were hospitalized from April 2009 to October 2014, with wound area ranging from 7 cm × 5 cm to 15 cm × 13 cm. The wounds were debrided as early as possible, and necrotic skulls were kept in situ and covered with porcine ADM and silver-containing dressing. Bacterial culture of exudate from the residual soft tissue was carried out 3 days after hospitalization. Pertinent antibiotics were applied topically to control infection, and autologous split-thickness skin grafts were transplanted. Two to three weeks after injury when the skin grafts survived, modified skin soft tissue expansion was carried out. The crossbow-form incision was made on the normal scalp 2 cm away from the edge of transplanted skin; a capsule cavity was formed by ladder-like dissection. An expander was inserted with the injection port laying outside. The expander was stretched by inflation and deflation. The incisions were sutured layer by layer. The time of continuing negative pressure drainage in the interval of expansion was extended. Volume of water reaching 2 to 3 times of the capacity of expander was injected for excessive expanding. The expanded skin flap was rotated to repair the wound after expansion was ended. RESULTS: Within 1 week after debridement, 4 kinds of bacteria were detected in the bacterial culture of wound exudate, including 4 cases of Staphylococcus aureus, 5 cases of Staphylococcus epidermidis, 5 cases of Pseudomonas aeruginosa, and 3 cases of Acinetobacter baumannii. A total of 26 expanders were imbedded. No infection or incision dehiscence in the expanding area or cracking and leakage of expander was observed during expanding period. Two to three months after injury, expanded skin flap transplantation was completed, and the wound was repaired. Raw wounds were seen in 4 expanded skin flaps after transfer, and they healed after dressing change. Punctiform ulceration at the seams of 2 flaps was observed one month after the operation, which healed after removing few pieces of sequestra by themselves. The other expanded skin flaps survived well. During the postoperative follow-up for 3 to 12 months, satisfactory appearance and hair growth was observed in the operation area. CONCLUSIONS: Repair of the devastating wound on the head due to electrical burn with modified skin soft tissue expansion could achieve the result of early wound covering and cosmetic repair without alopecia in one time.

Spin canting and metamagnetism in the first hybrid cobalt-hypoxanthine open framework with umr topology.

Hydrothermal reactions generated a cobalt-hypoxanthine framework [Co(3)(OH)(4)(Hpxt)(2)]⋅2H(2)O (H(2) pxt=6-hydroxypurine, 1⋅2H(2)O), which became a microporous framework [Co(3)(OH)(4)(Hpxt)(2)] (1) through a single-crystal-to-single-crystal transformation. Compound 1⋅2H(2)O shows a three-dimensional umr topological structure with two types of spiral channels constructed by rod-shaped {Co(3)(µ-OH)(4)(N-C-N)(2)(N-C-C-O)(2)} second building units (SBUs). The larger channel is filled by fourfold spiral water chains. An unprecedented µ(5)-O6,N3,N7,N9 coordination mode of the Hpxt anion was observed. Both complexes 1⋅2H(2)O and 1 qualitatively show similar metamagnetism from anti-parallel to parallel ferromagnetic cobalt-hydroxide chains. Compared with 1⋅2H(2)O, a smaller Curie constant and more negative Weiss constant in 1 indicate that the helical water chains tend to suppress antiferromagnetic coupling between Co(3)(OH)(4) ferromagnetic chains. Detailed magnetic studies of 1⋅2H(2)O revealed that the competitive interactions between interchain antiferromagnetic exchange coupling and single-ion anisotropy of Co(II) resulted in a partly canted antiferromagnetic sate in low fields. Anti-parallel arrangement of adjacent ferromagnetic chains in middle fields gives 3D antiferromagnetic ordering, and magnetic ground states in high fields are a parallel arrangement of ferromagnetic chains.

Solvent induced molecular magnetic changes observed in single-crystal-to-single-crystal transformation.

Single-crystal-to-single-crystal (SCSC) transformations have recently been found in some molecular magnets, which involve rearrangement or dynamic movement of molecular components of the crystals. Various stimuli such as guest removal, guest exchange, ligand exchange as well as redox reactions may induce SCSC transformations. To date, only a few molecular magnets are known to exhibit SCSC transformations, which often show high-dimensional robust structures. This review mainly focuses on magnetic complexes that are robust enough to experience SCSC transformations and show magnetic changes induced by solvents in due course. This contribution is organized according to the means of solvent treatment of molecular magnets, aiming at revealing magneto-structural correlation in such SCSC transformations.

Cu6S4 cluster based twelve-connected face-centered cubic and Cu19I4S12 cluster based fourteen-connected body-centered cubic topological coordination polymers.

Hydrothermal reaction of Cu(MeCO2)2, (4-pyridylthio)acetic acid and NH4SCN resulted in a twelve-connected face-centered cubic topological metal-organic framework [Cu3(pdt)2(CN)] (pdt = pyridinethiolate) in which Cu6S4 clusters act as twelve-connected nodes and pyridine rings and cyanides act as connectors. As an extension, an unprecedented fourteen-connected body-centered cubic coordination polymer [Cu19I4(pdt)12(SH)3] has been synthesized by three methods, in which nanosized chiral Cu19I4S12 clusters act as fourteen-connected nodes and triple pyridine rings and hydrosulfides act as connectors. The in situ S-C(sp(3)), S-C(sp(2)), and S-C(sp) cleavage reactions have been observed in the work.

Cuprophilicity-induced cocrystallization of [Cu2(4,4'-bpy)(CN)2]n sheets and [Cu(SCN)]n chains into a 3-D pseudopolyrotaxane.

The cocrystallization of [Cu(SCN)]n chains and [Cu2(4,4'-bpy)(CN)2]n (4,4'-bpy = 4,4'-bipyridine) layers generated a 3-D pseudopolyrotaxane compound, [Cu2(4,4'-bpy)(CN)2].[Cu(SCN)] (1), which can also be viewed as a 3-D network constructed by linkages of 2-D sheets and 1-D chains via unsupported CuI-CuI interactions. The CuI-CuI contact of 2.651(4) A in 1 is the shortest unsupported CuI-CuI distance documented to date, indicating cuprophilic attractions.