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The charged forms of π–conjugated chromophores are relevant in the field of organic electronics as charge carriers in optoelectronic devices, but also as energy storage substrates in organic batteries. In this context, intramolecular reorganization energy plays an important role in controlling material efficiency. In this work, we investigate how the diradical character influences the reorganization energies of holes and electrons by considering a library of diradicaloid chromophores. We determine the reorganization energies with the four-point adiabatic potential method using quantum–chemical calculations at density functional theory (DFT) level. To assess the role of diradical character, we compare the results obtained, assuming both closed-shell and open-shell representations of the neutral species. The study shows how the diradical character impacts the geometrical and electronic structure of neutral species, which in turn control the magnitude of reorganization energies for both charge carriers. Based on computed geometries of neutral and charged species, we propose a simple scheme to rationalize the small, computed reorganization energies for both n-type and p-type charge transport. The study is supplemented with the calculation of intermolecular electronic couplings governing charge transport for selected diradicals, further supporting the ambipolar character of the investigated diradicals.

The open star cluster NGC 1605 has recently been reported to in fact consist of two clusters (one intermediate-aged and one old) that merged via a flyby capture. Here we show that Gaia data do not support this scenario. We also report the serendipitous discovery of a new open cluster, Can Batll\'o 1, with a similar age and distance., Comment: Accepted by RNAAS. 2 pages, 1 figure. Online material here: https://github.com/fjaellet/ngc1605

Circularly polarized luminescence (CPL) and Raman optical activity (ROA) were observed in a single spectroscopic experiment for a purely organic molecule, an event that had so far been limited to lanthanide-based complexes. The present observation was achieved for [16]cycloparaphenylene lemniscate, a double macrocycle constrained by a rigid 9,9′-bicarbazole subunit, which introduces a chirality source and allows the molecule to be resolved into two configurationally stable enantiomers. Distortion of oligophenylene loops in this lemniscular structure produces a large magnetic transition dipole moment while maintaining the π-conjugation-induced enhancement of the Raman signal, causing the appearance of the CPL/ROA couple. A two-photon mechanism is proposed to explain the population of the lowest-energy excited electronic state prior to the simultaneous emission-scattering event. We thank MINECO/FEDER of the Spanish Government (project reference PGC2018-098533-B-100 and PID2021-127127NB-I00) and the Junta de Andalucía, Spain (UMA18FEDERJA057). We also thank the vibrational spectroscopy unit of the Research Central Services (SCAI) of the University of Málaga. Financial support from the National Science Center of Poland (DEC-2015/19/B/ST5/00612, M.S.) is gratefully acknowledged. L.F. thanks Thomas Vives from the Ecole Nationale Supérieure de Chimie of Rennes, the Shimadzu and Chiral Technology companies for their support regarding the separation of the chiral molecule by supercritical fluid chromatography (SFC). Funding for open access charge: Universidad de Málaga/CBUA

π−conjugated radicals have great promise for use in organic spintronics, however, the mechanisms of spin relaxation and mobility related to radical structural flexibility remain unexplored. Here, we describe a dumbbell shape azobenzene diradical and correlate its solid-state flexibility with spin relaxation and mobility. We employ a combination of X-ray diffraction and Raman spectroscopy to determine the molecular changes with temperature. Heating leads to: i) a modulation of the spin distribution; and ii) a “normal” quinoidal → aromatic transformation at low temperatures driven by the intramolecular rotational vibrations of the azobenzene core and a “reversed” aromatic → quinoidal change at high temperatures activated by an azobenzene bicycle pedal motion amplified by anisotropic intermolecular interactions. Thermal excitation of these vibrational states modulates the diradical electronic and spin structures featuring vibronic coupling mechanisms that might be relevant for future design of high spin organic molecules with tunable magnetic properties for solid state spintronics., In this manuscript, Negri, Zheng, Casado et al develop a stable and flexible diradical. Using a combination of experimental and theoretical techniques, they show how heating leads to change in the electronic and spin delocalizations ocurring between quinoidal and aromatic forms, and elucidate a unique spin-vibrational coupling.

A new compound (1) formed by two antiparallelly disposed tetracyano thienoquinoidal units has been synthesized and studied by electrochemistry, UV/Vis-NIR, IR, EPR, and transient spectroscopy. Self-assembly of 1 on a Au(111) surface has been investigated by scanning tunneling microscopy. Experiments have been rationalized by quantum chemical calculations. 1 exhibits a unique charge distribution in its anionic form, with a gradient of charge yielding a neat molecular in-plane electric dipole momentum, which transforms out-of-plane after surface deposition due to twisted→folded conformational change and to partial charge transfer from Au(111). Intermolecular van der Waals interactions and antiparallel trapezoidal shape fitting lead to the formation of an optimal dense on Au(111) two-dimensional assembly of 1., The authors thank the Spanish Ministry of Science, Innovation and Universities MCIU (projects CTQ2017-83531-R, RED2018-102815-T, MAT2017-85089-C2-1-R), Centro de Excelencia Severo Ochoa grants (SEV-2016-0686, SEV-2015-0496 and FUNFUTURE CEX2019-000917-S) and the CAM (QUIMTRONIC-CM project Y2018/NMT-4783). We thank MINECO/FEDER of the Spanish Government (projects PGC2018-098533-B-100 and PID2019-109555GB-I00), the Eusko Jaurlaritza (Basque Government, project PIBA19-0004) and the Junta de Andalucía, Spain (UMA18FEDERJA057). We also thank the Research Central Services (SCAI) of the University of Málaga and the Donostia International Physics Center (DIPC) Computer Center. We thank Dr. Juwon Oh and Prof. Donhgo Kim from the Spectroscopy Laboratory for Functional π-electronic Systems and Department of Chemistry, Yonsei University in Korea for the generous gift of the TRIR and UV/Vis transient absorption spectroscopy data.

The present paper is devoted to the study of the existence of a solution u for a quasilinear second order differential equation with homogeneous Dirichlet conditions, where the right-hand side tends to infinity at u = 0 . The problem has been considered by several authors since the 70's. Mainly, nonnegative right-hand sides were considered and thus only nonnegative solutions were possible. Here we consider the case where the right-hand side can change sign but is non negative (finite or infinite) at u = 0 , while no restriction on its growth at u = 0 is assumed on its positive part. We show that there exists a nonnegative solution in a sense introduced in the paper; moreover, this solution is stable with respect to the right-hand side and is unique if the right-hand side is nonincreasing in u. We also show that if the right-hand side goes to infinity at zero faster than 1 / | u | , then only nonnegative solutions are possible. We finally prove by means of the study of a one-dimensional example that nonnegative solutions and even many solutions which change sign can exist if the growth of the right-hand side is 1 / | u | γ with 0 γ 1 .

Background: Lesions in the temporomesial region can be reached by various approaches: subtemporal, transsylvian, transcortical, interhemispheric parieto-occipital, or supracerebellar transtentorial (SCTT). The choice varies according to the characteristics of the lesion and neighboring structures. Case Description: In this clinical case, it is presented a 56-year-old man with long-term evolution of drug-resistant epilepsy secondary to a cavernoma in the left parahippocampal gyrus. After assessing the lesion, it was decided a SCTT approach for its resection in a semi-sitting position, to avoid language disorders or visual damage. The surgery was uneventful and the patient did not present epileptic seizures during 6-month follow-up. Conclusion: Performing a SCTT is safe and feasible option for resection of lesions located in the basal temporomesial region without causing damage to neighboring structures, especially those located in the middle and posterior two-thirds of temporal region.

The search of compounds emitting in the near-infrared (NIR) has been accelerated owing to their use in biomedical and telecommunications applications. In this regard, nanographenes (NGs) are attractive materials adequate for integration with other technologies, which have recently demonstrated amplified spontaneous emission (ASE) and lasing across the visible spectrum. Here, the optical and ASE properties of four-zigzag edged NGs of the [m,n]peri-acenoacene family are reported, whose size is increased through conjugation extension by varying n (from 3 to 5) while keeping m = 2. Results show that such 1D conjugation extension method is more efficient in terms of shifting the photoluminescence (PL) to the infrared (PL at 710 nm in the larger compound, PP-Ar) than through 2D conjugation extension as in previously reported NGs (PL at 676 nm with the largest compound FZ3, with n = 3 and m = 4). Additionally, PP-Ar shows dual-ASE (at 726 and 787 nm), whose origin is elucidated through Raman and transient absorption spectroscopies. These compounds’ potential for red and NIR lasing is demonstrated through the fabrication of distributed feedback lasers with top-layer resonators. This study paves the way towards the development of stable low-cost all-plastic NIR lasers. The authors acknowledge financial support from the “Ministerio de Ciencia, Innovación y Universidades” of Spain, European Regional Development Fund and European Social Funds (MAT2015-66586-R, PDI2019-106114GB-I00, BES-2016-077681, PGC2018-098533-B-100 and RED2018-102815-T). J.C. thanks the Junta de Andalucía of Spain (UMA18FEDERJA057). The authors also thank the Research Central Services (SCAI) of the University of Málaga. F.G. acknowledges the Spanish Government for an FPI grant. G.M.P. thanks Fondazione Cariplo (grant no 2018-0979) for the financial support. J.W. acknowledges the “Agency for Science, Technology and Research of Singapore” for financial support from A*STAR AME grant (A20E5c0089). A.M.R. and F.S. have received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. [816313]).

We consider elliptic equations of Schrodinger type with a right-hand side fixed and with the linear part of order zero given by a potential $V$. The main goal is to study the optimization problem f...

The paper deals with the homogenization of a magneto-elastodynamics equation satisfied by the displacement $$u_\varepsilon $$ of an elastic body which is subjected to an oscillating magnetic field $$B_\varepsilon $$ generating the Lorentz force $$\partial _t u_\varepsilon \times B_\varepsilon $$ . When the magnetic field $$B_\varepsilon $$ only depends on time or on space, the oscillations of $$B_\varepsilon $$ induce an increase of mass in the homogenized equation. More generally, when the magnetic field is time-space dependent through a uniformly bounded component $$G_\varepsilon (t,x)$$ of $$B_\varepsilon $$ , besides the increase of mass the homogenized equation involves the more intricate limit g of $$\partial _t u_\varepsilon \times G_\varepsilon $$ which turns out to be decomposed in two terms. The first term of g can be regarded as a nonlocal Lorentz force the range of which is limited to a light cone at each point (t, x). The cone angle is determined by the maximal velocity defined as the square root of the ratio between the elasticity tensor spectral radius and the body mass. Otherwise, the second term of g is locally controlled in $$L^2$$ -norm by the compactness default measure of the oscillating initial energy.

International audience; In this paper we study the homogenization of a linear elastodynamics system in an elastic body with soft inclusions, which is embedded in a highly oscillating magnetic field. We show two limit behaviors according to the magnetic field. On the one hand, if the magnetic field has two different directions on the interface between the hard phase and the soft phase, then the limit of the displacement in the hard phase is independent of time, so that the magnetic field induces an effective infinite mass. On the other hand, if the magnetic field has a constant direction ξ on the interface, then the limit of the displacement in the hard phase and in the direction ξ is solution to an elastodynamics equation with a memory mass, a memory stress tensor and memory external forces depending on the initial conditions, which read as time convolutions with some kernel. When the magnetic has the same direction ξ in the soft phase with smooth inclusions, we prove that the space-average of the kernel is regular and that the limit of the overall displacement in the direction ξ is solution to a viscoelasticity equation.; Dans cet article on étudie l'homogénéisation d'un système en élastodynamique linéaire dans un corps élastique comportant des inclusions faiblement rigides, plongé dans un champ magnétique fortement oscillant. On distingue deux comportements limites distincts suivant le champ magnétique. D'une part, si le champ magnétique possède deux directions différentes à l'interface entre la phase rigide et les inclusions, alors le déplacement dans la phase rigide est indépendant du temps, de sorte que le champ magnétique induit une masse limite infinie. D'autre part, si le champ magnétique a une direction constante ξ à l'interface, alors le déplacement limite dans la phase rigide et dans la direction ξ est solution d'une équation d'élastodynamique comportant un terme de masse à mémoire, un tenseur de contraintes à mémoire et des forces externes à mémoire dépendant des conditions initiales, qui s'expriment comme des convolutions en temps avec un certain noyau. Lorsque le champ magnétique a la même direction constante ξ dans la phase non rigide avec des inclusions régulières, on montre que la moyenne spatiale du noyau de convolution est régulier et que la limite du déplacement global dans la direction ξ est solution d'une équation de viscoélasticité.

The efficient synthesis and electronic properties of two large‐size cove‐edged nanographenes (NGs), CN1 and CN2, are presented. X‐ray crystallographic analysis reveals a contorted backbone for both molecules owing to the steric repulsion at the inner cove position. Noticeably, the dominant structures of these molecules contain four (for CN1) or six (for CN2) localized C=C double bonds embedded in nine (for CN1) or twelve (for CN2) aromatic sextet rings according to Clar's formula, which is supported by bond length analysis and theoretical (NICS, ACID) calculations. Furthermore, Raman spectra exhibit a band associated with the longitudinal CC stretching mode of olefinic double bonds. Owing to the existence of the additional olefinic bonds, both compounds show a small band gap (1.84 eV for CN1 and 1.37 eV for CN2). They also display moderate fluorescence quantum yield (35 % for CN1 and 50 % for CN2) owing to the contorted geometry, which can suppress aggregation in solution. J.W. acknowleges financial support from the MOE Tier 3 programme (MOE2014-T3-1-004) and NRF Investigatorship (NRF-NRFI05-2019-0005). J.C. acknowledges MINECO and Junta de Andalucía of Spain projects (PGC2018-098533-BI00 and UMA18FEDERJA057). M.A.D.-G. and R.M.-M. thank support from MINECO through the research project MAT2015-66586-R and the FPI fellowship (no. BES-2016-077681), respectively.

This is the peer reviewed version of the following article: L. Palomo, R. Rodríguez, S. Medina, E. Quiñoá, J. Casado, F. Freire, F. J. Ramírez, Angew. Chem. Int. Ed. 2020, 59, 9080, which has been published in final form at https://doi.org/10.1002/anie.202000651. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions Poly(phenylacetylene)s are a family of helical polymers constituted by conjugated double bonds. Raman spectra of these polymers show a structural fingerprint of the polyene backbone which, in combination with its helical orientation, makes them good candidates to be studied by Raman optical activity (ROA). Four different well‐known poly(phenylacetylene)s adopting different scaffolds and ten different helical senses have been prepared. Raman and ROA spectra were recorded and allowed to establish ROA‐spectrum/helical‐sense relationships: a left/right‐handed orientation of the polyene backbone (Mhelix/Phelix) produces a triplet of positive/negative ROA bands. Raman and ROA spectra of each polymer exhibited the same profile, and the sign of the ROA spectrum was opposite to the lowest‐energy electronic circular dichroism (ECD) band, indicating a resonance effect. Resonance ROA appears then as an indicator of the helical sense of poly(phenylacetylene)s, especially for those with an extra Cotton band in the ECD spectrum, where a wrong helical sense is assigned based on ECD, while ROA alerts of this misassignment Financial support from MINECO (PGC2018‐098533‐B‐I00 and the Junta de Andalucía project reference (UMA18‐FEDERJA‐057) are acknowledged. Xunta de Galicia (ED431C 2018/30, Centro singular de investigación de Galicia accreditation 2016–2019, ED431G/09 and postdoctoral fellowship for R.R.) and the European Regional Development Fund (ERDF) are also gratefully acknowledged SI

Posttraumatic syringomyelia (PTS) is a well-reported phenomenon that usually takes place in the long-term course of patients following spinal cord injury. Different surgical procedures have been described: spinal cordectomy is usually a last option technique, but might be an excellent choice in patients with severe spinal cord injuries. We present a young patient with complete spinal cord injury after spine trauma, who developed posttraumatic syringomyelia with progressive motor deterioration twelve years after fixation. We performed a novel surgical technique (myelopexy) with excellent resolution of syringomyelia, sparing the negative implications of complete cord transection. Some artistic illustrations made by one of the corresponding authors are included, to better understanding of operative details. La siringomielia postraumática (SPT) es un fenómeno bien documentado, que suele ocurrir en la recuperación a largo plazo de los pacientes después de una lesión de la médula espinal. Se han descrito diferentes procedimientos quirúrgicos: la cordectomía de la médula espinal es generalmente una técnica que se considera como última opción, pero podría ser una excelente elección para pacientes con lesiones graves en dicha zona. Presentamos el caso de un paciente joven con una lesión completa de la médula espinal después de un traumatismo de la columna vertebral, que desarrolló una siringomielia postraumática con un deterioro motor progresivo 12 años después de la fijación. Aplicamos una novedosa técnica quirúrgica (mielopexia) con una excelente resolución de la siringomielia, evitando las implicaciones negativas de la transección completa de la médula. Se incluyen algunas ilustraciones realizadas por uno de los autores para una mejor comprensión de los detalles de la intervención quirúrgica.

The n-paraphenylene family comprises chains of phenylene units linked together by C-C bonds that are between single- and double-bonded, and where n corresponds to the number of phenylene units. In this work, we compare the response of the optical properties of different phenylene arrangements. We study linear chains (LPP), cyclic systems (CPPs), and non-conjugated cyclic systems with two hydrogenated phenylenes (H4[n]CPP). Particularly, the systems of interest in this work are [6]LPP, [12]- and [6]CPP and H4[6]CPP. This work combines Raman and infrared spectroscopies with absorption and fluorescence (one- and two-photon excitations) measured as a function of pressure up to maximum of about 25 GPa. Unprecedented crystallographic pressure-dependent results are shown on H4[n]CPP, revealing intramolecular &pi, &pi, interactions upon compression. These intramolecular interactions justify the H4[n]CPP singular optical properties with increasing fluorescence lifetime as a function of pressure.

International audience; A cycloparaphenylene-based molecular lemniscate (CPPL) was obtained in a short synthesis involving masked p-phenylene equivalents. The strained figure-eight geometry of CPPL is sustained by the incorporated 9,9'-bicarbazole subunit, which also acts as a stereogenic element. The shape of the distorted [16]cycloparaphenylene nanohoop embedded in CPPL is accurately approximated with a Booth lemniscate. The structure of CPPL, investigated using NMR and Raman spectroscopic methods, revealed strain-dependent features, consistent with the variable curvature of the ring. The electronic and optical properties of CPPL combine features more characteristic of smaller cycloparaphenylenes, such as a reduced optical bandgap and red-shifted fluorescence. CPPL was resolved into enantiomers, which are configurationally stable and provide strong chiroptical responses, including circularly polarized luminescence.

A complete experimental and theoretical study has been carried out for aromatic and quinoidal perylene‐based bridges substituted with bis(diarylamine) and bis(arylimine) groups respectively. The through‐bridge inter‐redox site electronic couplings (VAB) have been calculated for their respective mixed‐valence radical cation and radical anion species. The unusual similitudes of the resulting VAB values for the given structures reveal the intervention of molecular shapes with balanced semi‐quinoidal/semi‐aromatic structures in the charge delocalization. An identical molecular object equally responding to the injection of either positive or negative charges is rare in the field of organic π‐conjugated molecules. However, once probed herein for perylene‐based systems, it can be extrapolated to other π‐conjugated bridges. As a result, this work opens the door to the rational design of true ambipolar bulk and molecular conductors.

High pressures in the 0–10 GPa range cause molecules to deform in unusual ways. A series of precisely defined carbon nanohoops consisting of n para-linked phenyl groups, [n]-cycloparaphenylenes ([n]CPPs, n = 7, 8, 9, 10, and 12) were studied in this pressure range using Raman spectroscopy and density functional theory (DFT) and compared with more rigid smaller 5- and [6]CPPs and with the longer carbon nanotubes. The presented analysis sheds light on the different responses to pressure depending on the nanohoop size. Surprisingly, the pressure coefficients, the rate of the Raman shifts as a function of pressure, change at a particular pressure which is characteristic of each [n]CPP. We identified this pressure as the beginning of ovalization of the nanohoops in analogy to carbon nanotubes. This pressure induced ovalization is reversible in the range of pressure studied for [n]CPPs with n = 7, 9, 10, and 12. In the case of [8]CPP, we find a metastable conformation at 8 GPa with significantly changed dihedral angles of adjacent phenyls. This high pressure molecular phase of [8]CPP provides an example for a new mechanism of irreversibility involving different conformations upon high pressure treatment. Modeling provided atomic level insights into the changes of conformations and the development of aromatic vs quinonoid structures as a function of pressure.

Radical cations and dications of [n]CPP from n = 5 to n = 12 have been studied by Raman spectroscopy and density functional theory. Small [n]CPP dications owe their stability to the closed-shell electronic structure imposed by cyclic conjugation surpassing the destabilizing effect of ring strain and of the electron deficiency of the charged states. Large [n]CPP dications mitigate cyclic strain by forming diradicals. The Raman spectra reflect the balance among cyclic conjugation, cyclic strain and biradicaloid stabilization by finding an unexpected turning point in the frequency behavior of the G vibrational modes as a function of size. These Raman data represent the vibrational fingerprint of this rare form of conjugation which is central to stabilize both cations and dications of [n]CPP macrocycles.

A peculiar characteristic of open-shell singlet diradical molecules is the presence of a double exciton state (H,H → L,L) among low lying excited states. Recent high-level quantum-chemical investigations including a static and dynamic electron correlation have demonstrated that this state can become the lowest singlet excited state, a diagnostic fingerprint of the diradical system. Here we investigate the performance of less computationally demanding TDDFT calculations by employing two approaches: the spin-flip TDDFT scheme and TD calculations based on unrestricted broken symmetry antiparallel-spin reference configuration (TDUDFT). The calculations are tested on a number of recently synthesized, large conjugated systems displaying from moderate to large diradical character and showing experimental trace of the double exciton state. We show that spin-flip (SF) TDB3LYP calculations in the collinear approximation generally underestimate the excitation energy of the double exciton state. When the molecule displays a strong diradical character, the unrestricted antiparallel-spin reference configuration of TDUDFT calculations is characterized by strongly localized frontier molecular orbitals. We show that under these conditions the double exciton state is captured by TDUB3LYP calculations since it is described by singly excited configurations and its excitation energy can be accurately predicted. Owing to the improved description of the ground state, also the excitation energy of the single exciton H → L state generally improves at the TDUB3LYP level. With regard to the double exciton state, SF TDB3LYP performs slightly better for small to medium diradical character while a large diradical character (and strong orbital localization) is a prerequisite for the success of TDUB3LYP calculations whose quality otherwise deteriorates.

This is an open access article distributed under the Creative Commons Attribution License.-- This article belongs to the Special Issue "New and Old Technologies for Generation of Microarrays"., Nucleic Acid Programmable Protein Arrays (NAPPA) have emerged as a powerful and innovative technology for the screening of biomarkers and the study of protein-protein interactions, among others possible applications. The principal advantages are the high specificity and sensitivity that this platform offers. Moreover, compared to conventional protein microarrays, NAPPA technology avoids the necessity of protein purification, which is expensive and time-consuming, by substituting expression in situ with an in vitro transcription/translation kit. In summary, NAPPA arrays have been broadly employed in different studies improving knowledge about diseases and responses to treatments. Here, we review the principal advances and applications performed using this platform during the last years., We gratefully acknowledge financial support from the Carlos III Health Institute of Spain (ISCIII, FIS PI14/01538)-Fondos FEDER (EU). The Proteomics Unit belongs to ProteoRed, PRB2-ISCIII, supported by grant PT13/0001. P.D. is supported by a JCYL-EDU/346/2013 PhD scholarship., We acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

New stilbenoid and thiophenic compounds terminally functionalized with donor-donor, acceptor-acceptor, or donor-acceptor moieties and possessing a central [2.2]paracyclophane unit have been prepared, and their properties interpreted in terms of through-bond and through space π-electron delocalization (i.e., π-conjugations). Based on photophysical data, their excited-state properties have been described with a focus on the participation of the central [2.2]paracyclophane in competition with through-bond conjugation in the side arms. To this end, two-photon and one-photon absorption and emission spectroscopy, as a function of temperature, solvent polarity, and pressure in the solid state have been recorded. Furthermore, charge delocalization through the [2.2]paracyclophane in the neutral state and in the oxidized species (radical cations, dications and radical trications) has been investigated, allowing the elucidation of the vibrational Raman fingerprint of through-space charge delocalization. Thus, a complementary approach to both "intermolecular" excitation and charge delocalizations in [2.2]paracyclophane molecules is shown which can serve as models of charge and exciton migration in organic semiconductors.

Franco, Carlos et al., Charge transfer/transport in molecular wires over varying distances is a subject of great interest The feasible transport mechanisms have been generally accounted for on the basis of tunneling or superexchange charge transfer operating over small distances which progressively gives way to hopping transport over larger distances. The underlying molecular sequential steps that likely take place during hopping and the operative mechanism occurring at intermediate distances have received much less attention given the difficulty in assessing detailed molecular-level information. We describe here the operating mechanisms for unimolecular electron transfer/transport in the ground state of radical-anion mixed-valence derivatives occurring between their terminal perchlorotriphenylmethyl/ide groups through thiophene-vinylene oligomers that act as conjugated wires of increasing length up to 53 Å. The unique finding here is that the net transport of the electron in the larger molecular wires is initiated by an electron-hole dissociation intermediated by hole delocalization (conformationally assisted and thermally dependent) forming tran-sient mobile polaronic states in the bridge that terminate by an electron-hole recombination at the other wire extreme. On the con-trary for the shorter radical-anions our results suggest that a flickering resonance mechanism which is intermediate between hop-ping and superexchange is the operative one. We support these mechanistic interpretations by applying the pertinent biased kinetic models of the charge/spin exchange rates determined by electron paramagnetic resonance and by molecular structural level infor-mation obtained from UV-Vis and Raman spectroscopies and by quantum chemical modelling., We acknowledge the financial support from the Spanish MINECO/FEDER (grants CTQ2013-40480-R, CTQ2016- 7989-R, and CTQ2015-64618-R), Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (grant SEV2015-0496), the Generalitat de Catalunya (grants 2014SGR-17, 2014SGR-97, and XRQTC). We also acknowledge supercomputing resources provided by the Red Españ ola de Supercomputacion and the Networking Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBERBBN). The work carried out at the University of Malaga was supported by MINECO/FEDER through the reference projects CTQ2012-33733 andCTQ2015-69391-P. The “Servicios Centrales de Apoyo a la Investigacioń ” of the University of Malaga are also acknowledged by generous access to its facilities. I.A. acknowledges the Spanish Ministerio de Educacion Cultura y Deporte for a FPU PhD scholarship.

The reduced and oxidized states of an open-shell diindeno[b,i]anthracene (DIAn) derivative have been investigated by experimental and theoretical techniques. As a result of moderate biradical character and the ability of cyclopenta-fused scaffolds to stabilize both positive and negative charges, DIAn exhibits rich redox chemistry with four observable and isolable charged states. Structural and electronic properties of the DIAn system are brought to light by UV-vis-NIR and Raman spectroelectrochemical measurements. Aromatization of the diindeno-fused anthracene core upon successive single-electron injections is revealed through single-crystal X-ray diffraction of radical anion and dianion salts. We present a rare case where the pseudoaromatic/quinoidal ground state of a neutral biradical polycyclic hydrocarbon leads to a stable cascade of five redox states. Our detailed investigation of the transformation of molecular structure along all four redox events provides a clearer understanding of the nature of charge carriers in ambipolar organic field-effect transistors.

International audience; The combination of a bis-alkynyl-helicene moiety with two iron centers leads to novel electroactive species displaying unprecedented redox-triggered chiroptical switching. Upon oxidation, strong changes of vibrational modes (either local or extended coupled modes) are detected by vibrational circular dichroism and Raman optical activity. Remarkably, the sign of the optical rotation at 1.54 µm (that is, at wavelengths typically used for telecommunications) changes upon oxidation while the topology and stereochemistry of the helicene remain unchanged.

Thin film organic lasers represent a new generation of inexpensive, mechanically flexible devices for spectroscopy, optical communications and sensing. For this purpose, it is desired to develop highly efficient, stable, wavelength-tunable and solution-processable organic laser materials. Here we report that carbon-bridged oligo(p-phenylenevinylene)s serve as optimal materials combining all these properties simultaneously at the level required for applications by demonstrating amplified spontaneous emission and distributed feedback laser devices. A series of six compounds, with the repeating unit from 1 to 6, doped into polystyrene films undergo amplified spontaneous emission from 385 to 585 nm with remarkably low threshold and high net gain coefficients, as well as high photostability. The fabricated lasers show narrow linewidth (105 pump pulses for oligomers with three to six repeating units) and wavelength tunability across the visible spectrum (408–591 nm)., Thin film organic solid-state lasers are low-cost flexible devices which require efficient, stable, colour-tunable, solution-processable materials. Here, the authors show that oligo(p-phenylenevinylene)s simultaneously possess all such properties, as demonstrated by their use in laser devices.

The relationships between the chiroptical activity and the vibrational normal modes of epichlorohydrin have been investigated on the basis of a nonredundant internal coordinate definition not reported until now. These coordinates were verified by comparing, for the lower energy conformers, the diagonal quadratic force constants and were found to display similar values among conformers and to be consistent with the molecular structure of epichlorohydrin and its vibrational circular dichroism (VCD) spectrum. Boltzmann population factors were used to calculate the weighted sum of the individual VCD and IR spectra of the three lower energy conformers, which accurately fitted the experimental spectra of (R)-epichlorohydrin. The electric and magnetic transition dipole moments of the 24 vibrational normal modes were calculated for the most stable conformers. The combined analysis of these vectors and the normal mode description, given in terms of the potential energy distribution, allowed us to investigate the role of the functional groups (methylene, chlorine) and the type of internal coordinates (stretching, bending, etc.) in the chiroptical activity of the vibrations.