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The true structure of alternating conjugated polymers—the state‐of‐the‐art materials for many organic electronics—often deviates from the idealized picture. Homocoupling defects are in fact inherent to the widely used cross‐coupling polymerization methods. Nevertheless, many polymers still perform excellently in the envisaged applications, which raises the question if one should really care about these imperfections. This article looks at the relevance of chemical precision (and lack thereof) in conjugated polymers covering the entire spectrum from the molecular scale, to the micro and mesostructure, up to the device level. The different types of polymerization errors for the alkoxylated variant of the benchmark (semi)crystalline polymer poly[2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene (PBTTT) are identified, visualized, and quantified and a general strategy to avoid homocoupling is introduced. Through a combination of experiments and supported by simulations, it is shown that these coupling defects hinder fullerene intercalation and limit device performance as compared to the homocoupling‐free analog. This clearly demonstrates that structural defects do matter and should be generally avoided, in particular when the geometrical regularity of the polymer is essential. These insights likely go beyond the specific PBTTT derivatives studied here and are of general relevance for the wider organic electronics field. [ABSTRACT FROM AUTHOR]

While the Green‐Kubo and non‐equilibrium molecular dynamics methods have been compared quite extensively to calculate the thermal conductivity in inorganic compounds, there is currently a lack of comparison of these algorithms with the more recently developed approach‐to‐equilibrium molecular dynamics (AEMD) method for other types of materials such as organic semiconductors. To fill this gap, this article reports a theoretical description of thermal transport in single crystals made of terthiophene as prototypical system based on the three most popular molecular dynamics approaches. A systematic comparison of the computed values of thermal conductivity and its anisotropy is carried out and the strengths and weaknesses associated with each method are discussed. Although the three algorithms give essentially the same trends, this study points to the "AEMD" approach as the most suitable compromise between accuracy and computing cost. On the material aspects, the theoretical modeling yields an anisotropic character of the thermal transport in crystals whose out‐of‐plane thermal conductivity component is approximately twice larger than the in‐plane components. The AEMD approach is further used to investigate the influence of temperature on thermal transport in terthiophene. The trends are utterly rationalized by relying on the concepts of phonon mean free paths and phonon group velocities. [ABSTRACT FROM AUTHOR]

The charge transport of crystalline organic semiconductors is limited by dynamic disorder that tends to localize charges. It is the main hurdle to overcome in order to significantly increase charge carrier mobility. An innovative design that combines a chemical structure based on sulfur‐rich thienoacene with a solid‐state herringbone (HB) packing is proposed and the synthesis, physicochemical characterization, and charge transport properties of two new thienoacenes bearing a central tetrathienyl core fused with two external naphthyl rings: naphtho[2,3‐b]thieno‐[2′′′,3′′′:4′′,5′′]thieno[2″,3″:4′,5′]thieno[3′,2′‐b]naphtho[2,3‐b]thiophene (DN4T) and naphtho[1,2‐b]thieno‐[2′′′,3′′′:4′′,5′′]thieno[2′′,3′′:4′,5′]thieno[3′,2′‐b]naphtho[1,2‐b]thiophene are presented. Both compounds crystallize with a HB pattern structure and present transfer integrals ranging from 33 to 99 meV (for the former) within the HB plane of charge transport. Molecular dynamics simulations point toward an efficient resilience of the transfer integrals to the intermolecular sliding motion commonly responsible for strong variations of the electronic coupling in the crystal. Best device performances are reached with DN4T with hole mobility up to μ = 2.1 cm2 V−1s−1 in polycrystalline organic field effect transistors, showing the effectiveness of the electronic coupling enabled by the new aromatic core. These promising results pave the way to the design of high‐performing materials based on this new thienoacene, notably through the introduction of alkyl side‐chains. [ABSTRACT FROM AUTHOR]

The molecular properties of [1]benzothieno[3,2‐b][1]benzothiophene (BTBT) are vulnerable to structural modifications, which in turn are determined by the functionalization of the backbone. Hence versatile synthetic strategies are needed to discover the properties of this molecule. To address this, we have attempted heteroatom (oxygen) functionalization of BTBT by a concise and easily scalable synthesis. Fourfold hydroxy‐substituted BTBT is the key intermediate, from which the compounds 2,3,7,8‐bis(ethylenedioxy)‐[1]benzothieno[3,2‐b][1]benzothiophene and 2,3,7,8‐bis(methylenedioxy)‐[1]benzothieno[3,2‐b][1]benzothiophene are synthesized. The difference in ether functionalities on the BTBT scaffold influences the ionisation potential values substantially. The crystal structure reveals the transformation of the herringbone motif in bare BTBT towards π‐stacked columns in the newly synthesized derivatives. The results are further justified by the simulated HOMO levels of the model compound. [ABSTRACT FROM AUTHOR]

Rationale: Saponins are natural compounds presenting a high structural diversity whose structural characterization remains extremely challenging. Ideally, saponin structures are best established using nuclear magnetic resonance experiments conducted on isolated molecules. However, saponins are also increasingly characterized using tandem mass spectrometry (MS/MS) coupled with liquid chromatography, even if collision-induced dissociation (CID) experiments are often quite limited in accurately determining the saponin structure. Methods: We consider here ion mobility mass spectrometry (IMMS) as an orthogonal tool for the structural characterization of saponin isomers by comparing the experimental collisional cross sections (CCSs) of saponin ions with theoretical CCSs for candidate ion structures. Indeed, state-of-the-art theoretical calculations perfectly complement the experimental results, allowing the ion structures to be deciphered at the molecular level. Results: We demonstrate that ion mobility can contribute to the structural characterization of saponins because different saponin ions present significantly distinct CCSs. Depending on the nature of the cation (in the positive ion mode), the differences in CCSs can also be exacerbated, optimizing the gas-phase separation. When associated with molecular dynamics simulations, the CCS data can be used to describe the interactions between the cations, i.e. H+, Na+ and K+, and the saponin molecules at a molecular level. Conclusions: Our work contributes to resolve the relationship between the primary and secondary structures of saponin ions. However, it is obvious that the structural diversity and complexity of the saponins cannot be definitively unraveled by measuring a single numerical value, here the CCS. Consequently, the structural characterization of unknown saponins will be difficult to achieve based on IMMS alone. Nevertheless, we demonstrated that monodesmosidic and bidesmosidic saponins can be distinguished via IMMS. [ABSTRACT FROM AUTHOR]

The Seebeck coefficient of both electrons and holes in a family of ambipolar diketopyrrolopyrrole copolymers is investigated using field-effect gated measurements. It is found that at high carrier concentrations the magnitude of the Seebeck coefficients is not strongly dependent on the molecular structure of the backbone within this family of polymers. Additionally, the Seebeck coefficients of electrons and holes have very similar magnitudes showing that electrons and holes experience a similar energetic landscape. Subtle differences in the carrier concentration dependence between the polymers are observed, which are interpreted in terms of different degrees of energetic disorder on the basis of molecular dynamics and electronic structure simulations. [ABSTRACT FROM AUTHOR]

Host-guest complexes are formed by the creation of multiple noncovalent bonds between a large molecule (the host) and smaller molecule(s) or ion(s) (the guest(s)). Ion-mobility separation coupled with mass spectrometry nowadays represents an ideal tool to assess whether the host-guest complexes, when transferred to the gas phase upon electrospray ionization, possess an exclusion or inclusion nature. Nevertheless, the influence of the solution conditions on the nature of the observed gas-phase ions is often not considered. In the specific case of inclusion complexes, kinetic considerations must be taken into account beside thermodynamics; the guest ingression within the host cavity can be characterized by slow kinetics, which makes the complexation reaction kinetically driven on the timescale of the experiment. This is particularly the case for the cucurbituril family of macrocyclic host molecules. Herein, we selected para-phenylenediamine and cucurbit[6]uril as a model system to demonstrate, by means of ion mobility and collision-induced dissociation measurements, that the inclusion/exclusion topology ratio varies as a function of the equilibration time in solution prior to the electrospray process. [ABSTRACT FROM AUTHOR]

Charge carrier mobility is a central property that characterizes the performances of organic semiconductors and is mostly measured in field-effect transistors. High mobility values are sought by many research teams. This article, that provides an overview of best performing molecular semiconductors is constructed on the question: What currently limits charge carrier mobility in crystals of molecular semiconductors? With this in mind, we confront, in a critical way, the current theoretical understanding to the most salient experimental results with the hope to reach a deeper understanding based on first principles and order of magnitudes of the main physical parameters. [ABSTRACT FROM AUTHOR]

In this work, a new plasma diagnostic method has been used to quantify the plasma-generated species that play a part in the ethyl lactate plasma polymer film deposition. This method has been possible by using the RGA mass spectrometry combined with the in situ FTIR spectroscopy supported by DFT calculations. Ethyl lactate plasma phase can then be qualitatively and quantitatively probed by varying the experimental parameters. More specifically, it has been shown that by increasing the power from 30 to 280 W, the density of ester-bearing species in the plasma strongly decreases and supports the drop of ester content in plasma polymers. Additionally, the temperature of the plasma has been determined by the in situ IR spectroscopy and has revealed a too weak increase (60 K) to affect the fundamental vibrational levels. Our IR spectroscopy approach goes into that direction too. [ABSTRACT FROM AUTHOR]

Charge carrier mobility is a central property that characterizes the performances of organic semiconductors and is mostly measured in field-effect transistors. High mobility values are sought by many research teams. This article, that provides an overview of best performing molecular semiconductors is constructed on the question: What currently limits charge carrier mobility in crystals of molecular semiconductors? With this in mind, we confront, in a critical way, the current theoretical understanding to the most salient experimental results with the hope to reach a deeper understanding based on first principles and order of magnitudes of the main physical parameters. [ABSTRACT FROM AUTHOR]

The influence of the interface of the dielectric SiO2 on the performance of bottom-contact, bottom-gate poly(3-alkylthiophene) (P3 AT) field-effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin-coated from chlorobenzene (CB) onto the bare SiO2 dielectric is compared to those where the active layer is first spin-coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO2 surface. While an apparent alkyl side-chain length dependent mobility is observed for films directly spin-coated onto the SiO2 dielectric (with mobilities of ≈10−3 cm2 V−1 s−1 or less) for laminated films mobilities of 0.14 ± 0.03 cm2 V−1 s−1 independent of alkyl chain length are recorded. Surface-sensitive near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out-of-plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO2/film interface. A comparison with NEXAFS on crystalline P3 AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3 AT crystals suggest a close to crystalline polymer organization at the P3 AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent 'out-of-plane' orientation and high FET mobilities. [ABSTRACT FROM AUTHOR]

Noncovalent interactions between several protonated amines and an original ditopic receptor, nor-seco-cucurbit[10]uril, are investigated by combining mass spectrometry-based methods and computational chemistry. Electrospray ionization is used to transfer the intact supramolecular assemblies from their acidic solution to the gas phase, provided fine-tuning of the source parameters is achieved. Ternary complexes, associating two guest molecules and one host cavity, are observed systematically in the mass spectrometry analyses and the quasi-exclusive occurrence of these 2:1 associations reveals the allosteric nature of the complexation reaction. It is demonstrated that the binary 1:1 complex ions that are detected arise from collision-induced dissociation processes undergone by the ternary complex ions inside the ion source. Based on ion mobility experiments supported by theoretical calculations, the inclusion nature of the gas-phase ternary complexes is clearly evidenced independent of the size of the probed guest molecule and the charge state of the complex ions. The allosteric nature of the complexation reactions is dictated by size criteria. This is demonstrated on the basis of mass spectrometry experiments by analyzing solutions containing ligands of different sizes in competition for inclusion within the guest cavity. Computational chemistry is also used to characterize the three-dimensional structures of the complexes. [ABSTRACT FROM AUTHOR]

The back cover picture shows how a combination of experimental and theoretical tools proves attractive for the study of noncovalent interactions between a double‐cavity cucurbit[n]uril‐type receptor and size‐selected guest molecules. In their Full Paper on page 959 ff., P. Gerbaux and co‐workers describe that ternary complexes are smoothly transferred from aqueous solutions to the gas phase upon electrospray ionization. State‐of‐the‐art methods based on mass spectrometry associated with computational chemistry demonstrate the conservation of the condensed‐phase structure during the transfer. [ABSTRACT FROM AUTHOR]