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End-on binding of dinitrogen to low valent metal centres is common in transition metal chemistry but remains extremely rare in f-elements chemistry. In particular, heterobimetallic end-on N2 bridged complexes of lanthanides are unprecedented despite their potential relevance in catalytic reduction of dinitrogen. Here we report the synthesis and characterization of a series of N2 bridged heterobimetallic complexes of U(III), Ln(III) and Ln(II) which were prepared by reacting the Fe dinitrogen complex [Fe(depe)2(N2)] (depe = 1,2-bis(diethylphosphino)-ethane), complex A with [MIII{N(SiMe3)2}3] (M = U, Ce, Sm, Dy, Tm) and [LnII{N(SiMe3)2}2], (Ln = Sm, Yb). Despite the lack of reactivity of the U(III), Ln(III) and Ln(II) amide complexes with dinitrogen, the end-on dinitrogen bridged heterobimetallic complexes [{Fe(depe)2}(m-h1 :h1 -N2)(M{N(SiMe3)2}3)], 1-M (M = U(III), Ce(III), Sm(III), Dy(III) and Tm(III)), [{Fe(depe)2}(mh1 :h1 -N2)(Ln{N(SiMe3)2}2)], 1*-Ln (Ln = Sm(II), Yb(II)) and [{Fe(depe)2(m-h1 :h1 -N2)}2{SmII{N(SiMe3)2}2}], 3 could be prepared. The synthetic method used here allowed to isolate unprecedented end-on bridging N2 complexes of divalent lanthanides which provide relevant structural models for the species involved in the catalytic reduction of dinitrogen by Fe/Sm(II) systems. Computational studies showed an essentially electrostatic interaction of the end-on bridging N2 with both Ln(III) and Ln(II) complexes with the degree of N2 activation correlating with their Lewis acidity. In contrast, a back-bonding covalent contribution to the U(III)–N2Fe bond was identified by computational studies. Computational studies also suggest that end-on binding of N2 to U(III) and Ln(II) complexes is favoured for the iron-bound N2 compared to free N2 due to the higher N2 polarization.

First synthesized in 1991, EthynylBenziodoXolones (EBXs) - cyclic hypervalent iodine reagents derived from 2-iodobenzoic acid - are now among the most versatile electrophilic alkynylation reagents. Due to their cyclic structure, these reagents exhibit enhanced stability compared to previously used alkynyl iodonium salts. Over the last decade, both the iodoheterocycle and the arene ring have been extensively modified to fine-tune the reactivity of the reagents, resulting in new analogues such as Ethynylbenziodoxoles (EBxs) or N-heterocyclic reagents. In this article, we have for the first time compiled the structural data available for EBXs and their analogues, focusing especially on X-Ray and NMR data. For selected compounds, molecular electrostatic potentials (MEP) have also been calculated. When considering the tight relationship between structure and reactivity in hypervalent iodine reagents, the collected data is expected to be highly useful for further developments in the field.

Polymer semiconductors show unique combinations of mechanical and optoelectronic properties that strongly depend on their microstructure and morphology. Here, we have used a model π-conjugated bithiophene repeat unit to incorporate optoelectronic functionality into an aliphatic polyamide backbone by solution-phase polycondensation. Intermolecular hydrogen bonding between the amide groups ensured stable short-range order in the form of lamellar crystalline domains in the resulting semiaromatic polyamides, which could be processed from the melt and exhibited structural and thermomechanical characteristics comparable with those of existing engineering polyamides. At the same time, however, pulse-radiolysis time-resolved microwave conductivity measurements indicated charge carrier mobilities that were an order of magnitude greater than previously observed in bithiophene-based materials. Our results hence provide a convincing demonstration of the potential of amide hydrogen bonding interactions for obtaining unique combinations of mechanical and optoelectronic properties in thermoplastic polymers., Accepted Author Manuscript, ChemE/Opto-electronic Materials

Copper redox mediators can be employed in dye sensitized solar cells (DSCs) both as liquid electrolytes or as solid state hole transport materials (HTMs). The solid state devices that employ copper complex HTMs can be simply obtained by solvent evaporation in liquid state devices. During this evolution, the copper complex molecules present in the electrolyte solvent slowly aggregate in the pores of the TiO2 film and also close the gap between the TiO2 film and counter electrode. However, the crystallization of the HTM that infiltrated in the mesoscopic TiO2 pores can lead to low photovoltaic performance. In order to prevent this problem, we designed two copper redox mediators [Cu(beto)(2)](1+) (beto = 4,4'-diethoxy-6,6'-dimethyl-2,2'-bipyridine) and [Cu(beto(2Ox))(2)](1+) (beto(2Ox) = 4,4'-bis(2-methoxyethoxy)-6,6'-dimethyl-2,2'-bipyridine) with extended side chains. First, we studied these complexes in liquid state devices in reference to the [Cu(tmby)(2)](2+/1+) complex (tmby = 4,4',6,6'-tetramethyl-2,2'-bipyridine). The solar-to- electrical power conversion efficiencies for liquid state devices were over 10% for all of the complexes by using the organic Y123 dye under 1000 Wm(-2) AM1.5G illumination. However, solid state devices showed significantly diminished charge transport properties and short circuit current density values even though the crystallization was reduced.

Crystalline thin films of π-conjugated molecules are relevant as the active layers in organic electronic devices. Therefore, materials with enhanced control over the supramolecular arrangement, crystallinity, and thin film morphology are desirable. Here, we report that hydrogen-bonded substituents serve as additional structure-directing elements that positively affect crystallization, thin film morphology, and device performance of p-type organic semiconductors. We observed that a quaterthiophene diacetamide exhibited a denser packing than other quaterthiophenes in the single-crystal structure and, as a result, displayed enhanced intermolecular electronic interactions. This feature was preserved in crystalline thin films that exhibited a layer-by-layer morphology with large domain sizes and high internal order. As a result, organic field-effect transistors of these polycrystalline thin films showed mobilities in the range of the best mobilities values reported for single-crystalline quaterthiophenes. The use of hydrogen-bonded groups may, thus, provide an avenue for organic semiconducting materials with improved morphology and performance.

Polymer semiconductors show unique combinations of mechanical and optoelectronic properties that strongly depend on their microstructure and morphology. Here, we have used a model p-conjugated bithiophene repeat unit to incorporate optoelectronic functionality into an aliphatic polyamide backbone by solution-phase polycondensation. Intermolecular hydrogen bonding between the amide groups ensured stable short-range order in the form of lamellar crystalline domains in the resulting semiaromatic polyamides, which could be processed from the melt and exhibited structural and thermomechanical characteristics comparable with those of existing engineering polyamides. At the same time, however, pulse-radiolysis time-resolved microwave conductivity measurements indicated charge carrier mobilities that were an order of magnitude greater than previously observed in bithiophene-based materials. Our results hence provide a convincing demonstration of the potential of amide hydrogen bonding interactions for obtaining unique combinations of mechanical and optoelectronic properties in thermoplastic polymers., Peer Reviewed, Postprint (author's final draft)

Tetraarylethenes are obtained by acid‐induced coupling of vinyl triazenes with aromatic compounds. This new C−H activation route for the synthesis of aggregation‐ induced emission luminogens is simple, fast, and versatile. It allows the direct grafting of triarylethenyl groups onto a variety of aromatic compounds, including heterocycles, supramolecular hosts, biologically relevant molecules, and commercial polymers.

A series of neutral ruthenium(II)-arene complexes, [(arene) Ru(Q(R))Cl] (arene = p-cymene or hexamethylbenzene), containing 4-acyl-5-pyrazolonate (Q(R)) ligands with aromatic substituents in the acyl moiety (a phenyl in Q(Ph) and a 1-naphthyl in Q(naph)) and related ionic complexes [(arene)Ru(Q(R))(PTA)][PF6] (PTA = 1,3,5-triaza-7-phosphaadamantane) have been synthesized and characterized by IR, H-1, C-13 and P-31 NMR spectroscopy, elemental analysis and ESI mass spectrometry. The structures of five of these compounds were also determined by X-ray crystallography. DFT studies have been performed on all complexes and, in the case of two cationic [(arene) Ru(Q(naph))(PTA)][PF6], the existence of two conformers with a different relative orientation of the naphthyl group in the Q(naph) ligand has been assessed, showing that they possess similar energies, in agreement with the experimentally observed NMR spectra in solution. The cytotoxicity of the 4-acyl-5-pyrazolonate proligands (HQ(R)) and complexes was evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR) and non-tumorous human embryonic kidney (HEK293) cells. In general, each complex is about equally cytotoxic to all three cell lines and the PTA derivatives with the naphthyl-modified Q(R) ligands are the most active of the series.

A series of neutral ruthenium(II)-arene complexes, [(arene) Ru(Q(R))Cl] (arene = p-cymene or hexamethylbenzene), containing 4-acyl-5-pyrazolonate (Q(R)) ligands with aromatic substituents in the acyl moiety (a phenyl in Q(Ph) and a 1-naphthyl in Q(naph)) and related ionic complexes [(arene)Ru(Q(R))(PTA)][PF6] (PTA = 1,3,5-triaza-7-phosphaadamantane) have been synthesized and characterized by IR, H-1, C-13 and P-31 NMR spectroscopy, elemental analysis and ESI mass spectrometry. The structures of five of these compounds were also determined by X-ray crystallography. DFT studies have been performed on all complexes and, in the case of two cationic [(arene) Ru(Q(naph))(PTA)][PF6], the existence of two conformers with a different relative orientation of the naphthyl group in the Q(naph) ligand has been assessed, showing that they possess similar energies, in agreement with the experimentally observed NMR spectra in solution. The cytotoxicity of the 4-acyl-5-pyrazolonate proligands (HQ(R)) and complexes was evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR) and non-tumorous human embryonic kidney (HEK293) cells. In general, each complex is about equally cytotoxic to all three cell lines and the PTA derivatives with the naphthyl-modified Q(R) ligands are the most active of the series.

The multicomponent reaction of diboronic acids with a catechol and a tripyridyl linker results in the formation trigonal prismatic cages. The cages feature six dative boron-nitrogen bonds as structure-directing elements. The size of the cages can be varied by changing the diboronic acid building block. The cages are able to encapsulate polyaromatic molecules such as triphenylene or coronene.

Five different types of β-diketiminate ligands, bearing electron-donating to strongly electron-withdrawing substituents, were synthesized and used in the synthesis of Cp* ruthenium complexes (Cp* = η⁵-C₅Me₅). One series consists of complexes with a covalent RuIII–Cl bond, and the other series features a reduced RuII center, where the chloride is abstracted by treatment of the corresponding RuIII compounds with Zn or Mg. All compounds were characterized by single-crystal X-ray diffraction, UV–visible spectroscopy, and cyclic voltammetry. In the case of RuII complexes, solution NMR techniques provided key information regarding the electronic and structural differences induced by the different β-diketiminate ligands employed. Capitalizing on the facile reduction–oxidation cycle of the Cp* ruthenium β-diketiminato complexes, catalytic atom transfer radical addition (ATRA) and cyclization (ATRC) reactions were performed on relevant substrates. The turnover rates are strongly dependent on the type of β-diketiminate used, where ligands with electron-withdrawing substituents, i.e., trifluoromethyl groups, provided complexes that efficiently catalyze the addition of CCl₄ or toluenesulfonyl chloride to styrene. In contrast, complexes with electron-donating substituents on the β-diketiminate promoted efficient ATR cyclization of N-allyl-N-phenyltrichloroacetamide and 2,2,2-trichloroethyl ether. Thus, the overall product conversion and yield are dependent on matching the ligand substitution pattern of the catalyst to the type of substrate.

The new mixed-metal complex {anti-[(p-cymene)RuCl]-μ-[κ 2-P,P′;κ 1-P′′-(PPh2CH2)3CMe]-[AuCl]}PF6 and its cluster derivative {anti-[(p-cymene)RuCl]-μ-[κ 2-P,P′;κ 1-P′′-(PPh2CH2)3CMe]-[AuPt3(CO)3(PCy3)3]}(PF6)2 have been prepared and characterized. Notably, NMR spectroscopy and high resolution FT-ICR mass spectrometry, including a tandem mass spectrometric analysis, demonstrated the formation of these compounds that was also confirmed by single crystal X-ray diffraction analysis

Platform chemicals are usually derived from petrochemical feedstocks. A sustainable alternative commences with lignocellulosic biomass, a renewable feedstock, but one that is highly challenging to process. Ionic liquids (ILs) are able to solubilize biomass and, in the presence of catalysts, convert the biomass into useful platform chemicals. Herein, we demonstrate that mixtures of ILs are powerful systems for the selective catalytic transformation of cellulose into 5-hydroxymethylfurfural (HMF). Combining ILs with continuous HMF extraction into methyl-isobutyl ketone or 1,2-dimethoxyethane, which form a biphase with the IL mixture, allows the online separation of HMF in high yield. This one-step process is operated under relatively mild conditions and represents a significant step forward towards sustainable HMF production.

Tetraarylethenes are obtained by acid‐induced coupling of vinyl triazenes with aromatic compounds. This new C−H activation route for the synthesis of aggregation‐ induced emission luminogens is simple, fast, and versatile. It allows the direct grafting of triarylethenyl groups onto a variety of aromatic compounds, including heterocycles, supramolecular hosts, biologically relevant molecules, and commercial polymers.