@article{12879, abstract = {Machine learning (ML) has been widely applied to chemical property prediction, most prominently for the energies and forces in molecules and materials. The strong interest in predicting energies in particular has led to a ‘local energy’-based paradigm for modern atomistic ML models, which ensures size-extensivity and a linear scaling of computational cost with system size. However, many electronic properties (such as excitation energies or ionization energies) do not necessarily scale linearly with system size and may even be spatially localized. Using size-extensive models in these cases can lead to large errors. In this work, we explore different strategies for learning intensive and localized properties, using HOMO energies in organic molecules as a representative test case. In particular, we analyze the pooling functions that atomistic neural networks use to predict molecular properties, and suggest an orbital weighted average (OWA) approach that enables the accurate prediction of orbital energies and locations.}, author = {Chen, Ke and Kunkel, Christian and Cheng, Bingqing and Reuter, Karsten and Margraf, Johannes T.}, issn = {2041-6539}, journal = {Chemical Science}, publisher = {Royal Society of Chemistry}, title = {{Physics-inspired machine learning of localized intensive properties}}, doi = {10.1039/d3sc00841j}, year = {2023}, } @article{20968, abstract = {Several helically folded aromatic oligoamides were designed and synthesized. The sequences were all water-soluble thanks to the charged side chains borne by the monomers. Replacing a few, sometimes only two, charged side chains by neutral methoxy groups was shown to trigger the formation of various aggregates which could be tentatively assigned to head-to-head stacked dimers of single helices, double helical duplexes and a quadruplex, none of which would form in organic solvent with organic-soluble analogues. The nature of the aggregates was supported by concentration and solvent dependent NMR studies, 1H DOSY experiments, mass spectrometry, and X-ray crystallography or energy-minimized models, as well as analogies with earlier studies. The hydrophobic effect appears to be the main driving force for aggregation but it can be finely modulated by the presence or absence of a small number of charges to an extent that had no precedent in aromatic foldamer architectures. These results will serve as a benchmark for future foldamer design in water.}, author = {Teng, Binhao and Mandal, Pradeep K and Allmendinger, Lars and Douat, Céline and Ferrand, Yann and Huc, Ivan}, issn = {2041-6539}, journal = {Chemical Science}, number = {40}, pages = {11251--11260}, publisher = {Royal Society of Chemistry}, title = {{Controlling aromatic helix dimerization in water by tuning charge repulsions}}, doi = {10.1039/d3sc02020g}, volume = {14}, year = {2023}, } @article{20969, abstract = {The diastereoselective assembly of achiral constituents through a single spontaneous process into complex covalent architectures bearing multiple stereogenic elements still remains a challenge for synthetic chemists. Here, we show that such an extreme level of control can be achieved by implementing stereo-electronic information on synthetic organic building blocks and templates and that non-directional interactions (i.e., electrostatic and steric interactions) can transfer this information to deliver, after self-assembly, high-molecular weight macrocyclic species carrying up to 16 stereogenic elements. Beyond the field of supramolecular chemistry, this proof of concept should stimulate the on-demand production of highly structured polyfunctional architectures.}, author = {Zhang, Yuan and Ourri, Benjamin and Skowron, Pierre-Thomas and Jeamet, Emeric and Chetot, Titouan and Duchamp, Christian and Belenguer, Ana M. and Vanthuyne, Nicolas and Cala, Olivier and Dumont, Elise and Mandal, Pradeep K and Huc, Ivan and Perret, Florent and Vial, Laurent and Leclaire, Julien}, issn = {2041-6539}, journal = {Chemical Science}, number = {26}, pages = {7126--7135}, publisher = {Royal Society of Chemistry}, title = {{Self-assembly of achiral building blocks into chiral cyclophanes using non-directional interactions}}, doi = {10.1039/d3sc01235b}, volume = {14}, year = {2023}, } @article{20761, abstract = {We report a convenient protocol for a nitrogen atom insertion into indenes to afford isoquinolines. The reaction uses a combination of commercially available phenyliodine(III) diacetate (PIDA) and ammonium carbamate as the nitrogen source to furnish a wide range of isoquinolines. Various substitution patterns and commonly used functional groups are well tolerated. The operational simplicity renders this protocol broadly applicable and has been successfully extended towards the direct interconversion of cyclopentadienes into the corresponding pyridines. Furthermore, this strategy enables the facile synthesis of 15N labelled isoquinolines, using 15NH4Cl as a commercial 15N source.}, author = {Finkelstein, Patrick and Reisenbauer, Julia and Botlik, Bence B. and Green, Ori and Florin, Andri and Morandi, Bill}, issn = {2041-6539}, journal = {Chemical Science}, number = {11}, pages = {2954--2959}, publisher = {Royal Society of Chemistry}, title = {{Nitrogen atom insertion into indenes to access isoquinolines}}, doi = {10.1039/d2sc06952k}, volume = {14}, year = {2023}, } @article{20762, abstract = {A metal-free deaminative coupling of non-prefunctionalised benzylamines and arylboronic acids is reported. In this operationally simple reaction, a primary amine in benzylamine is converted into a good leaving group in situ using inexpensive and commercially available isoamyl nitrite as a nitrosating reagent. Lewis-acidic arylboronic acids are shown to replace mineral acids such as HCl or HBF4 that are conventionally used in the preparation of aryl diazonium salts. This unlocked the formation of the corresponding diarylmethanes by forging a new C–C bond in good yields. }, author = {Sirvinskaite, Giedre and Reisenbauer, Julia and Morandi, Bill}, issn = {2041-6539}, journal = {Chemical Science}, number = {7}, pages = {1709--1714}, publisher = {Royal Society of Chemistry}, title = {{Deaminative coupling of benzylamines and arylboronic acids}}, doi = {10.1039/d2sc06055h}, volume = {14}, year = {2023}, } @article{17866, abstract = {Electric fields have been used to control and direct chemical reactions in biochemistry and enzymatic catalysis, yet directly applying external electric fields to activate reactions in bulk solution and to characterize them ex situ remains a challenge. Here we utilize the scanning tunneling microscope-based break-junction technique to investigate the electric field driven homolytic cleavage of the radical initiator 4-(methylthio)benzoic peroxyanhydride at ambient temperatures in bulk solution, without the use of co-initiators or photochemical activators. Through time-dependent ex situ quantification by high performance liquid chromatography using a UV-vis detector, we find that the electric field catalyzes the reaction. Importantly, we demonstrate that the reaction rate in a field increases linearly with the solvent dielectric constant. Using density functional theory calculations, we show that the applied electric field decreases the dissociation energy of the O–O bond and stabilizes the product relative to the reactant due to their different dipole moments.}, author = {Zhang, Boyuan and Schaack, Cedric and Prindle, Claudia R. and Vo, Ethan A. and Aziz, Miriam and Steigerwald, Michael L. and Berkelbach, Timothy C. and Nuckolls, Colin and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {7}, pages = {1769--1774}, publisher = {Royal Society of Chemistry}, title = {{Electric fields drive bond homolysis}}, doi = {10.1039/d2sc06411a}, volume = {14}, year = {2023}, } @article{17870, abstract = {The electric fields created at solid–liquid interfaces are important in heterogeneous catalysis. Here we describe the Ullmann coupling of aryl iodides on rough gold surfaces, which we monitor in situ using the scanning tunneling microscope-based break junction (STM-BJ) and ex situ using mass spectrometry and fluorescence spectroscopy. We find that this Ullmann coupling reaction occurs only on rough gold surfaces in polar solvents, the latter of which implicates interfacial electric fields. These experimental observations are supported by density functional theory calculations that elucidate the roles of surface roughness and local electric fields on the reaction. More broadly, this touchstone study offers a facile method to access and probe in real time an increasingly prominent yet incompletely understood mode of catalysis.}, author = {Stone, Ilana B. and Starr, Rachel L. and Hoffmann, Norah and Wang, Xiao and Evans, Austin M. and Nuckolls, Colin and Lambert, Tristan H. and Steigerwald, Michael L. and Berkelbach, Timothy C. and Roy, Xavier and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {36}, pages = {10798--10805}, publisher = {Royal Society of Chemistry}, title = {{Interfacial electric fields catalyze Ullmann coupling reactions on gold surfaces}}, doi = {10.1039/d2sc03780g}, volume = {13}, year = {2022}, } @article{17874, abstract = {Redox-active two-dimensional polymers (RA-2DPs) are promising lithium battery organic cathode materials due to their regular porosities and high chemical stabilities. However, weak electrical conductivities inherent to the non-conjugated molecular motifs used thus far limit device performance and the practical relevance of these materials. We herein address this problem by developing a modular approach to construct π-conjugated RA-2DPs with a new polycyclic aromatic redox-active building block PDI-DA. Efficient imine-condensation between PDI-DA and two polyfunctional amine nodes followed by quantitative alkyl chain removal produced RA-2DPs TAPPy-PDI and TAPB-PDI as conjugated, porous, polycrystalline networks. In-plane conjugation and permanent porosity endow these materials with high electrical conductivity and high ion diffusion rates. As such, both RA-2DPs function as organic cathode materials with good rate performance and excellent cycling stability. Importantly, the improved design enables higher areal mass-loadings than were previously available, which drives a practical demonstration of TAPPy-PDI as the power source for a series of LED lights. Collectively, this investigation discloses viable synthetic methodologies and design principles for the realization of high-performance organic cathode materials.}, author = {Jin, Zexin and Cheng, Qian and Evans, Austin M. and Gray, Jesse and Zhang, Ruiwen and Bao, Si Tong and Wei, Fengkai and Venkataraman, Latha and Yang, Yuan and Nuckolls, Colin}, issn = {2041-6539}, journal = {Chemical Science}, number = {12}, pages = {3533--3538}, publisher = {Royal Society of Chemistry}, title = {{π-Conjugated redox-active two-dimensional polymers as organic cathode materials}}, doi = {10.1039/d1sc07157b}, volume = {13}, year = {2022}, } @article{21081, abstract = {Macrocyclic peptides are an important class of bioactive substances. When inserting an aromatic foldamer segment in a macrocyclic peptide, the strong folding propensity of the former may influence the conformation and alter the properties of the latter. Such an insertion is relevant because some foldamer–peptide hybrids have recently been shown to be tolerated by the ribosome, prior to forming macrocycles, and can thus be produced using an in vitro translation system. We have investigated the interplay of peptide and foldamer conformations in such hybrid macrocycles. We show that foldamer helical folding always prevails and stands as a viable means to stretch, i.e. unfold, peptides in a solvent dependent manner. Conversely, the peptide systematically has a reciprocal influence and gives rise to strong foldamer helix handedness bias as well as foldamer helix stabilisation. The hybrid macrocycles also show resistance towards proteolytic degradation.}, author = {Dengler, Sebastian and Mandal, Pradeep K and Allmendinger, Lars and Douat, Céline and Huc, Ivan}, issn = {2041-6539}, journal = {Chemical Science}, number = {33}, pages = {11004--11012}, publisher = {Royal Society of Chemistry}, title = {{Conformational interplay in hybrid peptide–helical aromatic foldamer macrocycles}}, doi = {10.1039/d1sc03640h}, volume = {12}, year = {2021}, } @article{17899, abstract = {Designing highly insulating sub-nanometer molecules is difficult because tunneling conductance increases exponentially with decreasing molecular length. This challenge is further enhanced by the fact that most molecules cannot achieve full conductance suppression with destructive quantum interference. Here, we present results for a series of small saturated heterocyclic alkanes where we show that conductance is suppressed due to destructive interference. Using the STM-BJ technique and density functional theory calculations, we confirm that their single-molecule junction conductance is lower than analogous alkanes of similar length. We rationalize the suppression of conductance in the junctions through analysis of the computed ballistic current density. We find there are highly symmetric ring currents, which reverse direction at the antiresonance in the Landauer transmission near the Fermi energy. This pattern has not been seen in earlier studies of larger bicyclic systems exhibiting interference effects and constitutes clear-cut evidence of destructive σ-interference. The finding of heterocyclic alkanes with destructive quantum interference charts a pathway for chemical design of short molecular insulators using organic molecules.}, author = {Zhang, Boyuan and Garner, Marc H. and Li, Liang and Campos, Luis M. and Solomon, Gemma C. and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {30}, pages = {10299--10305}, publisher = {Royal Society of Chemistry}, title = {{Destructive quantum interference in heterocyclic alkanes: The search for ultra-short molecular insulators}}, doi = {10.1039/d1sc02287c}, volume = {12}, year = {2021}, } @article{10350, abstract = {The misfolding and aberrant aggregation of proteins into fibrillar structures is a key factor in some of the most prevalent human diseases, including diabetes and dementia. Low molecular weight oligomers are thought to be a central factor in the pathology of these diseases, as well as critical intermediates in the fibril formation process, and as such have received much recent attention. Moreover, on-pathway oligomeric intermediates are potential targets for therapeutic strategies aimed at interrupting the fibril formation process. However, a consistent framework for distinguishing on-pathway from off-pathway oligomers has hitherto been lacking and, in particular, no consensus definition of on- and off-pathway oligomers is available. In this paper, we argue that a non-binary definition of oligomers' contribution to fibril-forming pathways may be more informative and we suggest a quantitative framework, in which each oligomeric species is assigned a value between 0 and 1 describing its relative contribution to the formation of fibrils. First, we clarify the distinction between oligomers and fibrils, and then we use the formalism of reaction networks to develop a general definition for on-pathway oligomers, that yields meaningful classifications in the context of amyloid formation. By applying these concepts to Monte Carlo simulations of a minimal aggregating system, and by revisiting several previous studies of amyloid oligomers in light of our new framework, we demonstrate how to perform these classifications in practice. For each oligomeric species we obtain the degree to which it is on-pathway, highlighting the most effective pharmaceutical targets for the inhibition of amyloid fibril formation.}, author = {Dear, Alexander J. and Meisl, Georg and Šarić, Anđela and Michaels, Thomas C. T. and Kjaergaard, Magnus and Linse, Sara and Knowles, Tuomas P. J.}, issn = {2041-6539}, journal = {Chemical Science}, keywords = {general chemistry}, number = {24}, pages = {6236--6247}, publisher = {Royal Society of Chemistry}, title = {{Identification of on- and off-pathway oligomers in amyloid fibril formation}}, doi = {10.1039/c9sc06501f}, volume = {11}, year = {2020}, } @article{17924, abstract = {We demonstrate that imidazole based π–π stacked dimers form strong and efficient conductance pathways in single-molecule junctions using the scanning-tunneling microscope-break junction (STM-BJ) technique and density functional theory-based calculations. We first characterize an imidazole-gold contact by measuring the conductance of imidazolyl-terminated alkanes (im-N-im, N = 3–6). We show that the conductance of these alkanes decays exponentially with increasing length, indicating that the mechanism for electron transport is through tunneling or super-exchange. We also reveal that π–π stacked dimers can be formed between imidazoles and have better coupling than through-bond tunneling. These experimental results are rationalized by calculations of molecular junction transmission using non-equilibrium Green's function formalism. This study verifies the capability of imidazole as a Au-binding ligand to form stable single- and π-stacked molecule junctions at room temperature.}, author = {Fu, Tianren and Smith, Shanelle and Camarasa-Gómez, María and Yu, Xiaofang and Xue, Jiayi and Nuckolls, Colin and Evers, Ferdinand and Venkataraman, Latha and Wei, Sujun}, issn = {2041-6539}, journal = {Chemical Science}, number = {43}, pages = {9998--10002}, publisher = {Royal Society of Chemistry}, title = {{Enhanced coupling through π-stacking in imidazole-based molecular junctions}}, doi = {10.1039/c9sc03760h}, volume = {10}, year = {2019}, } @article{17925, abstract = {Recent years have seen tremendous progress towards understanding the relation between the molecular structure and function of organic field effect transistors. The metrics for organic field effect transistors, which are characterized by mobility and the on/off ratio, are known to be enhanced when the intermolecular interaction is strong and the intramolecular reorganization energy is low. While these requirements are adequate when describing organic field effect transistors with simple and planar aromatic molecular components, they are insufficient for complex building blocks, which have the potential to localize a carrier on the molecule. Here, we show that intramolecular conductivity can play a role in controlling device characteristics of organic field effect transistors made with macrocycle building blocks. We use two isomeric macrocyclic semiconductors that consist of perylene diimides linked with bithiophenes and find that the trans-linked macrocycle has a higher mobility than the cis-based device. Through a combination of single molecule junction conductance measurements of the components of the macrocycles, control experiments with acyclic counterparts to the macrocycles, and analyses of each of the materials using spectroscopy, electrochemistry, and density functional theory, we attribute the difference in electron mobility of the OFETs created with the two isomers to the difference in intramolecular conductivity of the two macrocycles.}, author = {Ball, Melissa L. and Zhang, Boyuan and Fu, Tianren and Schattman, Ayden M. and Paley, Daniel W. and Ng, Fay and Venkataraman, Latha and Nuckolls, Colin and Steigerwald, Michael L.}, issn = {2041-6539}, journal = {Chemical Science}, number = {40}, pages = {9339--9344}, publisher = {Royal Society of Chemistry}, title = {{The importance of intramolecular conductivity in three dimensional molecular solids}}, doi = {10.1039/c9sc03144h}, volume = {10}, year = {2019}, } @article{17926, abstract = {N-heterocyclic carbenes (NHCs) bind very strongly to transition metals due to their unique electronic structure featuring a divalent carbon atom with a lone pair in a highly directional sp2-hybridized orbital. As such, they can be assembled into monolayers on metal surfaces that have enhanced stability compared to their thiol-based counterparts. The utility of NHCs to form such robust self-assembled monolayers (SAMs) was only recently recognized and many fundamental questions remain. Here we investigate the structure and geometry of a series of NHCs on Au(111) using high-resolution X-ray photoelectron spectroscopy and density functional theory calculations. We find that the N-substituents on the NHC ring strongly affect the molecule–metal interaction and steer the orientation of molecules in the surface layer. In contrast to previous reports, our experimental and theoretical results provide unequivocal evidence that NHCs with N-methyl substituents bind to undercoordinated adatoms to form flat-lying complexes. In these SAMs, the donor–acceptor interaction between the NHC lone pair and the undercoordinated Au adatom is primarily responsible for the strong bonding of the molecules to the surface. NHCs with bulkier N-substituents prevent the formation of such complexes by forcing the molecules into an upright orientation. Our work provides unique insights into the bonding and geometry of NHC monolayers; more generally, it charts a clear path to manipulating the interaction between NHCs and metal surfaces using traditional coordination chemistry synthetic strategies.}, author = {Lovat, Giacomo and Doud, Evan A. and Lu, Deyu and Kladnik, Gregor and Inkpen, Michael S. and Steigerwald, Michael L. and Cvetko, Dean and Hybertsen, Mark S. and Morgante, Alberto and Roy, Xavier and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {3}, pages = {930--935}, publisher = {Royal Society of Chemistry}, title = {{Determination of the structure and geometry of N-heterocyclic carbenes on Au(111) using high-resolution spectroscopy}}, doi = {10.1039/c8sc03502d}, volume = {10}, year = {2019}, } @article{21096, abstract = {By using a combination of readily accessible experimental and computational experiments in water, we explored the factors governing the association between polyanionic dyn[4]arene and a series of α,ω-alkyldiammonium ions of increasing chain length. We found that the lock-and-key concept based on the best match between the apolar and polar regions of the molecular partners failed to explain the observed selectivities. Instead, the dissection of the energetic and structural contributions demonstrated that the binding events were actually guided by two crucial solvent-related phenomena as the chain length of the guest increases: the expected decrease of the enthalpic cost of guest desolvation and the unexpected increase of the favourable enthalpy of complex solvation. By bringing to light the decisive enthalpic impact of complex solvation during the binding of polyelectrolytes by inclusion, this study may provide a missing piece to a puzzle that one day could display the global picture of molecular recognition in water.}, author = {Jeamet, Emeric and Septavaux, Jean and Héloin, Alexandre and Donnier-Maréchal, Marion and Dumartin, Melissa and Ourri, Benjamin and Mandal, Pradeep K and Huc, Ivan and Bignon, Emmanuelle and Dumont, Elise and Morell, Christophe and Francoia, Jean-Patrick and Perret, Florent and Vial, Laurent and Leclaire, Julien}, issn = {2041-6539}, journal = {Chemical Science}, number = {1}, pages = {277--283}, publisher = {Royal Society of Chemistry}, title = {{Wetting the lock and key enthalpically favours polyelectrolyte binding}}, doi = {10.1039/c8sc02966k}, volume = {10}, year = {2018}, } @article{21098, abstract = {The growth of crystals of aromatic compounds from water much depends on the nature of the water solubilizing functions that they carry. Rationalizing crystallization from water, and structure elucidation, of aromatic molecular and supramolecular systems is of general value across various fields of chemistry. Taking helical aromatic foldamers as a test case, we have validated several short polar side chains as efficient substituents to provide both solubility in, and crystal growth ability from, water. New 8-amino-2-quinolinecarboxylic acids bearing charged or neutral aminomethyl, carboxymethyl, sulfonic acid, or bis(hydroxymethyl)-methoxy side chains in position 4 or 5, were prepared on a multi gram scale. Fmoc protection of the main chain amine and suitable protections of the side chains ensured compatibility with solid phase synthesis. One tetrameric and five octameric oligoamides displaying these side chains were synthesized and shown to be soluble in water. In all cases but one, crystals were obtained using the hanging drop method, thus validating the initial design principle to combine polarity and rigidity. The only case that resisted crystallization appeared to be due to exceedingly high water solubility endowed by eight sulfonic acid functions. The neutral side chain did provide crystal growth ability from water but contributed poorly to solubility.}, author = {Hu, Xiaobo and Dawson, Simon J. and Mandal, Pradeep K and de Hatten, Xavier and Baptiste, Benoit and Huc, Ivan}, issn = {2041-6539}, journal = {Chemical Science}, number = {5}, pages = {3741--3749}, publisher = {Royal Society of Chemistry}, title = {{Optimizing side chains for crystal growth from water: a case study of aromatic amide foldamers}}, doi = {10.1039/c7sc00430c}, volume = {8}, year = {2017}, } @article{10374, abstract = {The formation of filaments from naturally occurring protein molecules is a process at the core of a range of functional and aberrant biological phenomena, such as the assembly of the cytoskeleton or the appearance of aggregates in Alzheimer's disease. The macroscopic behaviour associated with such processes is remarkably diverse, ranging from simple nucleated growth to highly cooperative processes with a well-defined lagtime. Thus, conventionally, different molecular mechanisms have been used to explain the self-assembly of different proteins. Here we show that this range of behaviour can be quantitatively captured by a single unifying Petri net that describes filamentous growth in terms of aggregate number and aggregate mass concentrations. By considering general features associated with a particular network connectivity, we are able to establish directly the rate-determining steps of the overall aggregation reaction from the system's scaling behaviour. We illustrate the power of this framework on a range of different experimental and simulated aggregating systems. The approach is general and will be applicable to any future extensions of the reaction network of filamentous self-assembly.}, author = {Meisl, Georg and Rajah, Luke and Cohen, Samuel A. I. and Pfammatter, Manuela and Šarić, Anđela and Hellstrand, Erik and Buell, Alexander K. and Aguzzi, Adriano and Linse, Sara and Vendruscolo, Michele and Dobson, Christopher M. and Knowles, Tuomas P. J.}, issn = {2041-6539}, journal = {Chemical Science}, keywords = {general chemistry}, number = {10}, pages = {7087--7097}, publisher = {Royal Society of Chemistry}, title = {{Scaling behaviour and rate-determining steps in filamentous self-assembly}}, doi = {10.1039/c7sc01965c}, volume = {8}, year = {2017}, } @article{17950, abstract = {Whilst most studies in single-molecule electronics involve components first synthesized ex situ, there is also great potential in exploiting chemical transformations to prepare devices in situ. Here, as a first step towards this goal, we conduct reversible reactions on monolayers to make and break covalent bonds between alkanes of different lengths, then measure the conductance of these molecules connected between electrodes using the scanning tunneling microscopy-based break junction (STM-BJ) method. In doing so, we develop the critical methodology required for assembling and disassembling surface-bound single-molecule circuits. We identify effective reaction conditions for surface-bound reagents, and importantly demonstrate that the electronic characteristics of wires created in situ agree with those created ex situ. Finally, we show that the STM-BJ technique is unique in its ability to definitively probe surface reaction yields both on a local (∼50 nm2) and pseudo-global (≥10 mm2) level. This investigation thus highlights a route to the construction and integration of more complex, and ultimately functional, surface-based single-molecule circuitry, as well as advancing a methodology that facilitates studies beyond the reach of traditional ex situ synthetic approaches.}, author = {Inkpen, Michael S. and Leroux, Yann R. and Hapiot, Philippe and Campos, Luis M. and Venkataraman, Latha}, issn = {2041-6539}, journal = {Chemical Science}, number = {6}, pages = {4340--4346}, publisher = {Royal Society of Chemistry}, title = {{Reversible on-surface wiring of resistive circuits}}, doi = {10.1039/c7sc00599g}, volume = {8}, year = {2017}, } @article{17951, abstract = {Thiophene-1,1-dioxide (TDO) oligomers have fascinating electronic properties. We previously used thermopower measurements to show that a change in charge carrier from hole to electron occurs with increasing length of TDO oligomers when single-molecule junctions are formed between gold electrodes. In this article, we show for the first time that the dominant conducting orbitals for thiophene/TDO oligomers of fixed length can be tuned by altering the strength of the electron acceptors incorporated into the backbone. We use the scanning tunneling microscope break-junction (STM-BJ) technique and apply a recently developed method to determine the dominant transport channel in single-molecule junctions formed with these systems. Through these measurements, we find that increasing the electron affinity of thiophene derivatives, within a family of pentamers, changes the polarity of the charge carriers systematically from holes to electrons, with some systems even showing mid-gap transport characteristics.}, author = {Low, Jonathan Z. and Capozzi, Brian and Cui, Jing and Wei, Sujun and Venkataraman, Latha and Campos, Luis M.}, issn = {2041-6539}, journal = {Chemical Science}, number = {4}, pages = {3254--3259}, publisher = {Royal Society of Chemistry}, title = {{Tuning the polarity of charge carriers using electron deficient thiophenes}}, doi = {10.1039/c6sc05283e}, volume = {8}, year = {2017}, } @article{7292, abstract = {Rechargeable Li–O2 batteries have amongst the highest formal energy and could store significantly more energy than other rechargeable batteries in practice if at least a large part of their promise could be realized. Realization, however, still faces many challenges than can only be overcome by fundamental understanding of the processes taking place. Here, we review recent advances in understanding the chemistry of the Li–O2 cathode and provide a perspective on dominant research needs. We put particular emphasis on issues that are often grossly misunderstood: realistic performance metrics and their reporting as well as identifying reversibility and quantitative measures to do so. Parasitic reactions are the prime obstacle for reversible cell operation and have recently been identified to be predominantly caused by singlet oxygen and not by reduced oxygen species as thought before. We discuss the far reaching implications of this finding on electrolyte and cathode stability, electrocatalysis, and future research needs.}, author = {Mahne, Nika and Fontaine, Olivier and Thotiyl, Musthafa Ottakam and Wilkening, Martin and Freunberger, Stefan Alexander}, issn = {2041-6539}, journal = {Chemical Science}, number = {10}, pages = {6716--6729}, publisher = {RSC}, title = {{Mechanism and performance of lithium–oxygen batteries – a perspective}}, doi = {10.1039/c7sc02519j}, volume = {8}, year = {2017}, }