Direct growth of crystalline triazine-based graphdiyne using surface-assisted deprotection-polymerisation.

Graphdiyne polymers have interesting electronic properties due to their π-conjugated structure and modular composition. Most of the known synthetic pathways for graphdiyne polymers yield amorphous solids because the irreversible formation of carbon-carbon bonds proceeds under kinetic control and because of defects introduced by the inherent chemical lability of terminal alkyne bonds in the monomers. Here, we present a one-pot surface-assisted deprotection/polymerisation protocol for the synthesis of crystalline graphdiynes over a copper surface starting with stable trimethylsilylated alkyne monomers. In comparison to conventional polymerisation protocols, our method yields large-area crystalline thin graphdiyne films and, at the same time, minimises detrimental effects on the monomers like oxidation or cyclotrimerisation side reactions typically associated with terminal alkynes. A detailed study of the reaction mechanism reveals that the deprotection and polymerisation of the monomer is promoted by Cu(ii) oxide/hydroxide species on the as-received copper surface. These findings pave the way for the scalable synthesis of crystalline graphdiyne-based materials as cohesive thin films.

Development of metal-free layered semiconductors for 2D organic field-effect transistors.

To this day, the active components of integrated circuits consist mostly of (semi-)metals. Concerns for raw material supply and pricing aside, the overreliance on (semi-)metals in electronics limits our abilities (i) to tune the properties and composition of the active components, (ii) to freely process their physical dimensions, and (iii) to expand their deployment to applications that require optical transparency, mechanical flexibility, and permeability. 2D organic semiconductors match these criteria more closely. In this review, we discuss a number of 2D organic materials that can facilitate charge transport across and in-between their π-conjugated layers as well as the challenges that arise from modulation and processing of organic polymer semiconductors in electronic devices such as organic field-effect transistors.

Immobilization of an Iridium Pincer Complex in a Microporous Polymer for Application in Room-Temperature Gas Phase Catalysis.

An iridium dihydride pincer complex [IrH2 (POCOP)] is immobilized in a hydroxy-functionalized microporous polymer network using the concepts of surface organometallic chemistry. The introduction of this novel, truly innocent support with remote OH-groups enables the formation of isolated active metal sites embedded in a chemically robust and highly inert environment. The catalyst maintained high porosity and without prior activation exhibited efficacy in the gas phase hydrogenation of ethene and propene at room temperature and low pressure. The catalyst can be recycled for at least four times.

Metal-Assisted and Solvent-Mediated Synthesis of Two-Dimensional Triazine Structures on Gram Scale.

Covalent triazine frameworks are an emerging material class that have shown promising performance for a range of applications. In this work, we report on a metal-assisted and solvent-mediated reaction between calcium carbide and cyanuric chloride, as cheap and commercially available precursors, to synthesize two-dimensional triazine structures (2DTSs). The reaction between the solvent, dimethylformamide, and cyanuric chloride was promoted by calcium carbide and resulted in dimethylamino-s-triazine intermediates, which in turn undergo nucleophilic substitutions. This reaction was directed into two dimensions by calcium ions derived from calcium carbide and induced the formation of 2DTSs. The role of calcium ions to direct the two-dimensionality of the final structure was simulated using DFT and further proven by synthesizing molecular intermediates. The water content of the reaction medium was found to be a crucial factor that affected the structure of the products dramatically. While 2DTSs were obtained under anhydrous conditions, a mixture of graphitic material/2DTSs or only graphitic material (GM) was obtained in aqueous solutions. Due to the straightforward and gram-scale synthesis of 2DTSs, as well as their photothermal and photodynamic properties, they are promising materials for a wide range of future applications, including bacteria and virus incapacitation.

Trends and challenges for microporous polymers.

Microporous polymers are covalently bound, entirely organic materials which possess very high surface areas. These materials have been intensively studied within recent years and various interesting properties and possible applications have been discovered and described. This review article starts with the question, what makes microporous polymers special and are there certain features which differentiate them from other microporous materials? Indeed, there are some special structural and functional features found in microporous polymers which make them really unique and merit further exploration. We focus here on microporous polymers which are solution-processable, can be produced as thin films on electrodes by oxidative polymerizations, are π-conjugated organic semiconductors, or which provide the possibility to introduce and exploit distinct functional groups in an otherwise non-functional highly porous environment. Emerging applications for these microporous polymers which make explicit use of these unique features are further presented.

Room-Temperature Activation of Hydrogen by Semi-immobilized Frustrated Lewis Pairs in Microporous Polymer Networks.

Porous polymer networks based on sterically encumbered triphenylphosphine motifs, mimicking the basic sites employed in frustrated Lewis pair (FLP) chemistry, were synthesized via Yamamoto polymerization and their interactions with the strong Lewis acid B(C6F5)3 probed. The combinations yield semi-immobilized FLPs, which are able to cleave dihydrogen heterolytically at ambient temperature and low hydrogen pressure.

Copper-Free Sonogashira Coupling for High-Surface-Area Conjugated Microporous Poly(aryleneethynylene) Networks.

A modified one-pot Sonogashira cross-coupling reaction based on a copper-free methodology has been applied for the synthesis of conjugated microporous poly(aryleneethynylene) networks (CMPs) from readily available iodoarylenes and 1,3,5-triethynylbenzene. The polymerization reactions were carried out by using equimolar amounts of halogen and terminal alkyne moieties with extremely small loadings of palladium catalyst as low as 0.65 mol %. For the first time, CMPs with rigorously controlled structures were obtained without any indications of side reactions, as proven by FTIR and solid-state NMR spectroscopy, while showing Brunauer-Emmett-Teller (BET) surface areas higher than any poly(aryleneethynylene) network reported before, reaching up to 2552 m(2) g(-1) .

Chemistry and structures of hexakis(halogenomethyl)-, hexakis(azidomethyl)-, and hexakis(nitratomethyl)disiloxanes.

An investigation of the structures and chemistry of substituted hexamethyl disiloxanes ((XCH2)3Si)2O; X=F, Cl, Br, I, N3 , and ONO2) is reported. New synthetic routes to the precursor hexakis(chloromethyl)disiloxane are presented. The products with X=Cl, Br, I, and N3 were characterized by NMR, IR, and Raman spectroscopy. In addition, the single-crystal structures of the products with X=Cl, Br, and I are discussed in detail. The compounds with X=F and ONO2 were not obtained in their pure form; instead investigations of the decomposition products revealed their conversion into intermediates. Theoretical calculations of the gas-phase structures at the B3LYP/cc-pVDZ, B3LYP/3-21G, MP2/6-31G*, and MP2/3-21G levels of theory are used to explain the chemical and physical behavior of the compounds with X=Cl, Br, I, N3, and ONO2. A new decomposition pathway of hexakis(nitratomethyl)disiloxane is presented and is used to explain their remarkable instability. The energetic properties and values of the nitrate and azide derivatives were calculated at the CBS-4M level of theory by using the improved EXPLO5 computer code version 6.01.