Two‐Dimensional Ketone‐Driven Metal–Organic Coordination on Cu(111)

Two‐dimensional metal–organic nanostructures based on the binding of ketone groups and metal atoms were fabricated by depositing pyrene‐4,5,9,10‐tetraone (PTO) molecules on a Cu(111) surface. The strongly electronegative ketone moieties bind to either copper adatoms from the substrate or codeposited iron atoms. In the former case, scanning tunnelling microscopy images reveal the development of an extended metal–organic supramolecular structure. Each copper adatom coordinates to two ketone ligands of two neighbouring PTO molecules, forming chains that are linked together into large islands through secondary van der Waals interactions. Deposition of iron atoms leads to a transformation of this assembly resulting from the substitution of the metal centres. Density functional theory calculations reveal that the driving force for the metal substitution is primarily determined by the strength of the ketone–metal bond, which is higher for Fe than for Cu. This second class of nanostructures displays a structural dependence on the rate of iron deposition.     

On‐Surface Metalation and 2D Self‐Assembly of Pyrphyrin Molecules Into Metal‐Coordinated Networks on Cu(111)

The metalation of the tetradentate molecule pyrphyrin by copper substrate atoms on a Cu(111) surface is studied. Pyrphyrin, in contrast to porphyrin, consists of four fused pyridine groups instead of pyrrol groups. Using thermal desorption spectroscopy (TDS ) and N 1s X‐ray photoelectron spectroscopy (XPS ), we show that metalation of the monolayer of pyrphyrin with Cu atoms from the Cu(111) surface occurs at 377 K. The formation of an extended two‐dimensional (2D) network is observed with scanning tunneling microscopy (STM ). A honeycomb‐like lattice of metalated pyrphyrin molecules is formed by intermolecular connection via the two cyano groups at the periphery of pyrphyrin as well as Cu adatoms. Dehydrogenation at the periphery of the molecule is observed during annealing at 520 K. The surface‐adsorbed metal‐pyrphyrin has the potential to serve as a molecular catalyst.     

Tailoring Large Pores of Porphyrin Networks on Ag(111) by Metal–Organic Coordination

The engineering of nanoarchitectures to achieve tailored properties relevant for macroscopic devices is a key motivation of organometallic surface science. To this end, understanding the role of molecular functionalities in structure formation and adatom coordination is of great importance. In this study, the differences in formation of Cu‐mediated metal–organic coordination networks based on two pyridyl‐ and cyano‐bearing free‐base porphyrins on Ag(111) are elucidated by use of low‐temperature scanning tunneling microscopy (STM). Distinct coordination networks evolve via different pathways upon codeposition of Cu adatoms. The cyano‐terminated module directly forms 2D porous networks featuring fourfold‐coordinated Cu nodes. By contrast, the pyridyl species engage in twofold coordination with Cu and a fully reticulated 2D network featuring a pore size exceeding 3 nm² only evolves via an intermediate structure based on 1D coordination chains. The STM data and complementary Monte Carlo simulations reveal that these distinct network architectures originate from spatial constraints at the coordination centers. Cu adatoms are also shown to form two‐ and fourfold monoatomic coordination nodes with monotopic nitrogen‐terminated linkers on the very same metal substrate—a versatility that is not achieved by other 3d transition metal centers but consistent with 3D coordination chemistry. This study discloses how specific molecular functionalities can be applied to tailor coordination architectures and highlights the potential of Cu as coordination center in such low‐dimensional structures on surfaces.     

On‐surface Synthesis of a Semiconducting 2D Metal–Organic Framework Cu3(C6O6) Exhibiting Dispersive Electronic Bands

A 2D metal–organic framework (2D‐MOF) was formed on a Cu(111) substrate using benzenehexol molecules. By means of a combination of scanning tunneling microscopy and spectroscopy, X‐ray photoelectron spectroscopy and density‐functional theory, the structure of the 2D‐MOF is determined to be Cu₃(C₆O₆), which is stabilized by O–Cu–O bonding motifs. We find that upon adsorption on Cu(111), the 2D‐MOF features a semiconductor band structure with a direct band gap of 1.5 eV. The O–Cu–O bonds offer efficient charge delocalization, which gives rise to a highly dispersive conduction band with an effective mass of 0.45 m_e at the band bottom, implying a high electron mobility in this material.     

Lattice‐Matched Epitaxial Growth of Organic Heterostructures for Integrated Optoelectronic Application

Development of nanowire photonics requires integration of different nanowire components into highly ordered functional heterostructures. Herein, we report a sequential self‐assembly of binary molecular components into branched nanowire heterostructures (BNHs) via lattice‐matched epitaxial growth, in which the microribbon backbone of 2,5‐Bis(5‐tert‐butyl‐2‐benzoxazolyl)thiophene (BBOT) functions as blue‐emitting microlaser source to pump the nanowire branches of BODIPY. By constructing Au electrodes on both branch sides and measuring the photocurrent in them, we successfully realize the integration of an organic laser and a power meter in a single device. This work provides a new insight into the integration of 1D organic nanostructures into BNHs for realizing organic multifunctional photonic devices.     

Click approach to the three‐component synthesis of novel β‐hydroxy‐1,2,3‐triazoles catalysed by new (Cu/Cu2O) nanostructure as a ligand‐free,green and regioselective nanocatalyst in water

Copper nanostructures were produced as an effective and regioselective catalyst for the synthesis of 1,2,3‐triazoles from a wide range of raw materials, such as sodium azide, epoxides and terminal alkynes, in water via a one‐pot three‐component click reaction. The new heterogeneous catalyst was prepared by a simple ball mill reduction of CuO with NaBH₄ using a ball‐to‐powder weight ratio of 50:1 under air atmosphere at room temperature. The catalyst was fully characterized using scanning electron microscopy, energy‐dispersive X‐ray analysis, Fourier transform infrared spectroscopy and X‐ray diffraction. The copper nanostructures catalysed both ring opening and triazole cyclization steps. Products were obtained in high yields and short reaction times. The reactions were performed at ambient temperature in water as a green solvent. The Cu/Cu₂O nanostructures revealed high reusability and high stability via a simple recycling process.     

Selective [5,5]‐Sigmatropic Rearrangement by Assembly of Aryl Sulfoxides with Allyl Nitriles

Aromatic [5,5]‐sigmatropic rearrangement is an appealing protocol for accessing 1,4‐substituted arenes. However, such a protocol has not been well utilized in organic synthesis because of the difficulties in the synthesis of the substrates, selectivity issues, and limited substrate scope. Described herein is a new [5,5]‐sigmatropic reaction utilizing readily available aryl sulfoxides and allyl nitriles. This reaction features mild reaction conditions, high chemo‐ and regioselectivity, excellent functional‐group compatibility, and broad substrate scope. Computational studies suggest that the success of the reaction can be attributed to the selective electrophilic assembly of the rearrangement precursors, in which a linear ‐C=C=N‐ linkage favors [5,5]‐sigmatropic rearrangement over the competitive [3,3]‐sigmatropic rearrangement.     

Oligothiophene Self‐Assembly on the Surface of ZnO Nanorods: Toward Coaxial p–n Hybrid Heterojunctions

We describe herein the design, synthesis and detailed structural characterization of hybrid 1D nanostructures. They are prepared by supramolecular self‐assembly of oligothiophene molecules on the surface of zinc oxide nanorods in solution at room temperature. Electronic absorption spectroscopy and X‐ray diffraction show that both organic and inorganic components in the coaxial p–n heterojunctions are crystalline. Especially, it is demonstrated that the organic compounds form a self‐assembled monolayer at the surface of the nanorods, which is not the case when zinc oxide quantum dots are instead used. As a result of their hybrid nature, the 1D nanostructures lead to ambipolar semiconducting nanostructured materials as active layers in field‐effect transistors.     

Well‐Defined Metal–Organic Framework Hollow Nanocages

Metal–organic frameworks (MOFs) have demonstrated great potentials in a variety of important applications. To enhance the inherent properties and endow materials with multifunctionality, the rational design and synthesis of MOFs with nanoscale porosity and hollow feature is highly desired and remains a great challenge. In this work, the formation of a series of well‐defined MOF (MOF‐5, Fe^II‐MOF‐5, Fe^III‐MOF‐5) hollow nanocages by a facile solvothermal method, without any additional supporting template is reported. A surface‐energy‐driven mechanism may be responsible for the formation of hollow nanocages. The addition of pre‐synthesized poly(vinylpyrrolidone)‐ (PVP) capped noble‐metal nanoparticles into the synthetic system of MOF hollow nanocages yields the yolk–shell noble metal@MOF nanostructures. The present strategy to fabricate hollow and yolk–shell nanostructures is expected to open up exciting opportunities for developing a novel class of inorganic–organic hybrid functional nanomaterials.     

Three‐Dimensional Ordered Antibody Arrays Through Self‐Assembly of Antibody–Polymer Conjugates

Three‐dimensional (3D) ordered arrays of human immunoglobulin G (IgG) were fabricated using well‐defined full‐length antibody–polymer conjugates (APCs). The conjugates were prepared through a two‐step sequential click approach with a combination of oxime ligation and strain promoted alkyne–azide cycloaddition. They were able to self‐assemble into lamellar nanostructures with alternating IgG and poly(N ‐isopropylacrylamide) (PNIPAM) nanodomains. As a proof‐of‐concept, these materials were fabricated into thin films and their specific binding ability was tested. The nanostructure not only improves the packing density and the proper orientation of the IgG, but also provides nanochannels to facilitate substrate transport.     

A Three‐Dimensional Porous Organic Semiconductor Based on Fully sp2‐Hybridized Graphitic Polymer

Dimensionality plays an important role in the charge transport properties of organic semiconductors. Although three‐dimensional semiconductors, such as Si, are common in inorganic materials, imparting electrical conductivity to covalent three‐dimensional organic polymers is challenging. Now, the synthesis of a three‐dimensional π‐conjugated porous organic polymer (3D p‐POP) using catalyst‐free Diels–Alder cycloaddition polymerization followed by acid‐promoted aromatization is presented. With a surface area of 801 m² g^?1, full conjugation throughout the carbon backbone, and an electrical conductivity of 6(2)×10^?4 S cm^?1 upon treatment with I₂ vapor, the 3D p‐POP is the first member of a new class of permanently porous 3D organic semiconductors.     

DNA–Polymer Nanostructures by RAFT Polymerization and Polymerization‐Induced Self‐Assembly

Nanostructures derived from amphiphilic DNA–polymer conjugates have emerged prominently due to their rich self‐assembly behavior; however, their synthesis is traditionally challenging. Here, we report a novel platform technology towards DNA–polymer nanostructures of various shapes by leveraging polymerization‐induced self‐assembly (PISA) for polymerization from single‐stranded DNA (ssDNA). A “grafting from” protocol for thermal RAFT polymerization from ssDNA under ambient conditions was developed and utilized for the synthesis of functional DNA–polymer conjugates and DNA–diblock conjugates derived from acrylates and acrylamides. Using this method, PISA was applied to manufacture isotropic and anisotropic DNA–polymer nanostructures by varying the chain length of the polymer block. The resulting nanostructures were further functionalized by hybridization with a dye‐labelled complementary ssDNA, thus establishing PISA as a powerful route towards intrinsically functional DNA–polymer nanostructures.     

Photovoltaic response to structural modifications on a series of conjugated polymers based on 2‐aryl‐2H‐benzotriazoles

The synthesis, characterization, and photovoltaic properties of a series of four conjugated polymers containing 2‐aryl‐2H‐benzotriazoles and “bis(thiopheno)dialkylfluorenes” is described. The polymers were obtained via Suzuki‐polycondensation and comprise alternating electron rich and electron poor building blocks. The impact of systematic structural changes on the electronic and morphological properties and device efficiencies were studied. Application of these polymers as light‐harvesting and electron‐donating materials in organic solar cells using PCBM derivatives as electron accepting materials resulted in power conversion efficiencies up to 1.8%. Both the properties of the pristine polymers and the device performance show that the impact of the substitution farther‐off the backbone is negligible while substitution directly on the backbone has a major impact. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Static investigation of adsorption and hetero‐diffusion of copper,silver, and gold adatoms on the (111) surface

In this work, we have used the static molecular simulations combined with an interatomic potential derived from the embedded‐atom method to study the adsorption and hetero‐diffusion on the (111) surface of Cu, Ag, and Au adatoms by using LAMMPS code. The investigation is performed for six heterogeneous systems such as Ag/Au(111), Ag/Cu(111), Au/Ag(111), Au/Cu(111), Cu/Ag(111), and Cu/Au(111). First, we have investigated the relaxation trends and the bond lengths of the atoms in the systems. The calculation results show that, the top layer spacing between the first and second layers of the Au(111), Ag(111), and Cu(111) substrates is contracted. This contraction is found to be more important in the Au(111) substrate. On the other hand, the strong reduction of the binding length is found in Au/Cu(111) for the different adsorption sites. In addition, the binding, adsorption, and static activation energies for all studied systems were examined. The results indicated that the binding and adsorption energies reached their maximum values in the Au/Cu(111) and Au/Ag(111) systems, respectively. Moreover, the static activation barriers for hopping diffusion on the (111) surfaces are found to be low compared with those found in the (100) and (110) surfaces. Therefore, our calculations showed that the difference in energy between the hcp and fcc sites on the (111) surfaces is very small. Copyright © 2017 John Wiley & Sons, Ltd.     

Copper‐Catalyzed Triboration: Straightforward,Atom‐Economical Synthesis of 1,1,1‐Triborylalkanes from Terminal Alkynes and HBpin

A convenient and efficient one‐step synthesis of 1,1,1‐triborylalkanes was achieved via sequential dehydrogenative borylation and double hydroborations of terminal alkynes with HBpin (HBpin=pinacolborane) catalyzed by inexpensive and readily available Cu(OAc)₂. This process proceeds under mild conditions, furnishing 1,1,1‐tris(boronates) with wide substrate scope, excellent selectivity, and good functional‐group tolerance, and is applicable to gram‐scale synthesis without loss of yield. The 1,1,1‐triborylalkanes can be used in the preparation of α‐vinylboronates and borylated cyclic compounds, which are valuable but previously rare compounds. Different alkyl groups can be introduced stepwise via base‐mediated deborylative alkylation to produce racemic tertiary alkyl boronates, which can be readily transformed into useful tertiary alcohols.     

Divergent Gold(I)‐Catalyzed Skeletal Rearrangements of 1,7‐Enynes

The gold(I) complex catalyzed cycloisomerization and skeletal rearrangement of 1,n‐enynes (n=5–7) is a powerful methodology for the efficient synthesis of complex molecular architectures. In contrast to 1,6‐enynes, readily accessible homologous 1,7‐enynes are largely unexplored in such transformations. Here, the divergent skeletal rearrangement of all‐carbon 1,7‐enynes by catalysis with a cationic gold(I) complex is reported. Depending on electronic and steric factors, differently substituted 1,7‐enynes react via different carbocations formed from a common gold carbene intermediate to yield on the one hand novel exocyclic allenes and on the other hand tricyclic hexahydro‐anthracenes through a novel dehydrogenative Diels–Alder reaction.     

Fabrication of Hierarchically Structured MOF‐Co3O4 on Well‐aligned CuO Nanowire with an Enhanced Electrocatalytic Property

Engineering appropriate shape and size of three‐dimensional inorganic nanostructures materials is of one the main critical problems in pursuing high‐performance electrode materials. Herein, we fabricate a metal‐organic framework derived cobalt oxide (Co₃O₄) are grown on copper oxide nanowire (CuO NWs) supported on the surface of 3D copper foam substrate. The highly aligned CuO NWs were prepared by using electrochemical anodization of copper foam in ambient temperature and followed by MOF Co₃O₄ was grown via a simple in situ solution deposition then consequent calcination process. The obtained binder‐free 3D CuO NWs@Co₃O₄ nanostructures were further characterized by using X‐ray diffraction, X‐ray photoelectron spectroscopy, field‐emission scanning electron microscopy, and transmission electron microscopy. Furthermore, electrochemical sensing of glucose was studied by using Cyclic Voltammetry, and chronoamperometry techniques. Interestingly, 3D CuO NWs@Co₃O₄ electrode exhibits excellent performance for the oxidation of glucose compared with individual entities. The proposed sensor shows wide linear ranges from 0.5 μM to 0.1 mM with the sensitivity of 6082 μA/μM and the lowest detection limit (LOD) of 0.23 μM was observed with the signal to noise ratio, (S/N) of 3. The superior catalytic oxidation of glucose mainly is endorsed by the excellent electrical conductivity and synergistic effect of the Co₃O₄ and CuO NWs.     

Electrodeposition of Au monolayer on Pt(111) mediated by self-assembled monolayers

In-situ scanning tunneling microscopy (STM), cyclic voltammetry (CV), and infrared reflection-adsorption spectroscopy (IRRAS) have been used to examine the electrodeposition of gold onto Pt(111) electrodes modified with benzenethiol (BT) and benzene-1,2-dithiol (BDT) in 0.1 M HClO4 containing 10 microM HAuCl4. Both BT and BDT were attached to Pt(111) via one sulfur headgroup. STM and IRRAS results indicated that the other SH group of BDT was pendant in the electrolyte. Both BT and BDT formed (2 x 2) structures at the coverage of 0.25, and they were transformed into (square root(3) x square root(3))R30 degrees as the coverage was raised to 0.33. These two organic surface modifiers resulted in 3D and 2D gold islands at BT- and BDT-coated Pt(111) electrodes, respectively. The pendant SH group of BDT could interact specifically with gold adspecies to immobilize gold adatoms on the Pt(111) substrate, which yields a 2D growth of gold deposition. Molecular resolution STM revealed an ordered array of (6 x 2 square root(13)) after a full monolayer of gold was plated on the BDT/Pt(111) electrode. Since BDT was strongly adsorbed on Pt(111), gold adatoms only occupied free sites between BDT admolecules on Pt(111). This is supported by a stripping voltammetric analysis, which reveals no reductive desorption of BDT admolecules at a gold-deposited BDT/Pt(111) electrode. It seems that the BDT adlayer acted as the template for gold deposit on Pt(111). In contrast, a BT adlayer yielded 3D gold deposit on Pt(111). This study demonstrates unambiguously that organic surface modifiers could contribute greatly to the electrodeposition of metal adatoms.     

Two‐Dimensional Boron Monolayers Mediated by Metal Substrates

Two‐dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure‐search method, both based on first‐principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B₁₂ is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate‐dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal.     

A Straightforward One‐Pot Synthesis of 3,4‐Dihydroquinazoline‐2(1H)‐thione Derivatives in Aqueous Organic Solvent

A novel and efficient method has been developed for the synthesis of a series of 3,4‐dihydroquinazoline‐2(1H)‐thione derivatives in aqueous organic solvent starting from 3‐(2‐aminophenyl)acrylates with isothiocyanates via a tandem intermolecular nucleophilic addition/intramolecular Michael addition reaction under mild conditions. A broad substrate scope has been demonstrated, which shows wide functional group tolerance and chemical specialization. The efficiency of the methodology could make this process available on gram‐scale.