Untangling the eclectronic propierties of triindole-based semiconductors

Organic semiconductors have emerged as an important class of materials that offer interesting prospects for high throughput, low-cost and flexible electronic circuits. In this sense, triindole-based systems have demonstrated great potential as p-type semiconductors in organic field-effect transistors (OFETs).[1] Recently, we have performed a combined experimental and theoretical study of three new crystalline N-trimethyltriindoles endowed with different functionalities at 3, 8 and 13 positions, either unsubstituted or with three methoxy or acetyl groups (Figure 1a), with the main goal of exploring the correlation between the electronic nature of the substituents and their solid-state organization, electronic properties and semiconductor behavior.[2] On the other hand, the design and synthesis of covalent organic framework materials (constructed from the union of different covalently linked conjugated platforms) are being deeply investigated in organic electronics.[3] In line with this , we have also investigated how the structural and the electronic properties of 2D triindole-based polymers (Figure 1b) can be modulated by the (i) modification of the linkage position from para (T2) to meta (T3), (ii) by the insertion of different π-bridges between the cores and (iii) by the increment of the number of π-bridges from 3 to 6 units (T2,3).[4] Overall, the results of this work open the door to the control of the degree of the π-conjugation for their subsequent synthesis and real application in organic electronic devices.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Biodiversity and distribution of macroinfauna assemblages on sandy beaches along the Gulf of Cadiz (SW Spain)

In the current study, the macroinfauna communities inhabiting 12 sandy beaches along the Spanish coast of the Gulf of Cadiz were describe in order to characterize their unexplored biodiversity, their zonation patterns and their environmental features. A total of 66 macroinfauna taxa were recorded on 12 sandy beaches, ranging from 4 to 33 species. Density reached 848 individual per m2. The individual zonation pattern ranged from two to three zones, regardless of the morphodynamic state. A common zonation pattern of the whole set of beaches was established, comprising three across-shore biological zones. Generally, the supralittoral zone was typified by the air-breathing amphipod Talitrus saltator and coleopterans; the middle zone was dominated by true intertidal species, such as Haustoriidae amphipods (Haustorius arenarius), Cirolanidae isopods (Eurydice affinis), Spionidae polychaetes (Scolelepis spp.) and nemerteans; and the lower or sublittoral zone was typified by Pontoporeiidae amphipods, mysids and spionid polychaetes. Sediment moisture, average grain size, organic matter content and elevation were the main predictor variables of zonation patterns. We used the conservation and recreation potential indices to show how this information can be useful for coastal management. Most beaches studied show a score above 5 on the conservation index, so the beaches have a reasonable potential for conservation management.En el presente estudio, se describen las comunidades de macroinfauna de doce playas arenosas de la costa española del Golfo de Cádiz con el objetivo de caracterizar su biodiversidad, sus patrones de zonación, y sus características ambientales. Un total de 66 taxones de macroinfauna fueron registrados en las playas de estudio, oscilando entre 4 y 33 especies, mientras que la densidad total fue de 848 individuos por m2. El patrón de zonación individual varió de dos a tres zonas, independientemente del estado morfodinámico de la playa. Se estableció un patrón de zonación común de todo el conjunto de playas, formado por tres zonas biológicas. En general, la zona supralitoral fue tipificada por el anfípodo Talitrus saltator y diversas familias de coleópteros. La zona media fue dominada por verdaderas especies intermareales, como anfípodos de la famila Haustoriidae (Haustorius arenarius), isópodos cirolánidos (Eurydice affinis), poliquetos (Scolelepis spp.) y nemertinos. La zona sublitoral se caracterizó por anfípodos de la familia Pontoporeiidae, misidáceos y poliquetos espiónidos. La humedad del sedimento, el tamaño medio de grano, el contenido en materia orgánica y la elevación fueron las principales variables influyentes en los patrones de zonación. Por último, toda esta información fue integrada para la aplicación de los índices de Conservación y Recreación, para mostrar cómo esta información puede ser útil para la gestión costera. La mayoría de las playas mostraron una puntuación superior a 5 en el Índice de Conservación, indicando un razonable potencial para la conservación.Gobierno de Andalucía P09- HUM-4717Ministerio de Educación AP-2009-390

Theoretical understanding of the increment of upon protonation of pyridine peripheral octupolar molecules: Toward nonlinear optical sensors

6 pages, 6 tables, 4 figures.In this article, we present a computational study of the nonlinear optical properties of pyridine-based octupolar molecules in their neutral and fully triprotonated states. The effect of the core substitution and the degree of conjugation with the periphery has been also established and confirms the possibility of fine-tuning the nonlinear optical response. Computations involving the time-dependent density-functional theory approach serve to further explore the existence of excited states with nonzero dipole moment. From these results, the origin of the high second-order nonlinear optical activity upon protonation is addressed.The present work was supported in part by the Dirección General de Enseñanza Superior DGES, MEC, Spain through research Project Nos. CTQ2006-14987-C02-01 and CTQ2005-01368. The authors are also indebted to Junta de Andalucía and Gobierno de Aragón Spain for funding their research groups FQM-0159 and E39. M.C.R.D. is grateful to the MEC/Fulbright for her Postdoctoral Fellowship at the Georgia Institute of Techology. J.C. is grateful to the MEC of Spain for an I3 professorship position of Chemistry at the University of Málaga and M.M.O. acknowledges the MEC for a personal grant.Peer reviewe

Untangling the electronic and charge transport properties of new Naphthalene and Perylene Diimides based-semiconductors

Organic semiconductors have emerged as an important class of materials that offer interesting prospects for high throughput, low-cost and flexible electronic circuits. Nevertheless, high performance electron-transporting (n-type) semiconductors are still rare compared to their high efficiency hole-transporting (p-type) counterparts. In this sense, the development of high-mobility and environmentally stable n-type materials for thin-film transistors has experienced a tremendous impetus in the last decade. Naphthalene-diimides (NDIs), perylene-diimides (PDIs) and their derivatives have demonstrated great potential as n-type semiconductors in Organic Field-Effect Transistors (OFETs). In this project, a mixed experimental and theoretical study of four new semiconductors (Figure 1) has been carried out with the aim to explore the impact of the following effects on the electronic and charge-transport properties: (i) the extension of the conjugated platform, going from a shorter conjugated core in naphthalene-diimides to a larger conjugated core in perylenediimides, (ii) the different donor units attached to the cores. For that, IR, UV-Vis absorption spectroscopy, and spectroelectrochemical measurements have been used in combination with theoretical calculations based on the Density Functional Theory (DFT). In addition, the four studied compounds have been implemented in OFETs , to assess their potential as active materials in organic electronics.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Piezochromic properties of a D-A-D platform: A joint experimental and theoretical perspective

Organic π-conjugated molecules with mechanochromic luminescence properties have attracted great interest in the last two decades due to their numerous applications in the optoelectronic field, such as sensors, probes and security inks. Materials that modify their colour under pressure are known as piezochromic materials. Usually, this variation is provoked by changes in the molecular structure, for example, crystal-to-amorphous phase transitions, modifications in dihedral angles or bond distances, and intermolecular interactions. The molecule proposed in this study is a TADF (Thermally activated delayed fluorescence) U-shaped molecule composed by two donors and one acceptor (D-A-D) units with a π-conjugated skeleton [1]. It was synthetized as a powder which under different crystallization methods gives rise to different conformers varying the dihedral angle of the bond that links the D and A units. The donors are two phenothiazine units and the acceptor is a dibenzo[a,j]phenazine unit located in the central core. Two different conformers have been analysed: the quasi equatorial - quasi equatorial (denoted as 1R) and the quasi axial - quasi axial (denoted as 1Y). In this project, we study the configurational changes triggering the piezochromic effects combining density functional theory (DFT) calculations with Raman spectroscopy experiments of the 1R and 1Y conformers during heating or in compression via a sapphire anvil cell [2]. Both show pressure and temperature dependence properties. Besides, these changes are reversible meaning that when the stimuli stop they revert to its original conformation. When these molecules are exposed to different ambient (like pressure or temperature variations) they evolved to a third conformer with an intermediate dihedral angle that results in different Raman, emission and absorption behaviour.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Prato Tour on Carbon Nanotubes: Raman Insights

[EN] The functionalisation of carbon nanotubes has been instrumental in broadening its application field, allowing especially its use in biological studies. Although numerous covalent and non-covalent functionalisation methods have been described, the characterisation of the final materials has always been an added challenge. Among the various techniques available, Raman spectroscopy is one of the most widely used to determine the covalent functionalisation of these species. However, Raman spectroscopy is not a quantitative technique, and no studies are reported comparing its performance when the same number of functional groups are added but using completely different reactions. In this work, we have experimentally and theoretically studied the functionalisation of carbon nanotubes using two of the most commonly used reactions: 1,3-dipolar cycloaddition of azomethylene ylides and diazonium-based radical addition. The number of groups introduced onto the tubes by these reactions has been determined by different characterisation techniques. The results of this study support the idea that data obtained by Raman spectra are only helpful for comparing functionalisations produced using the same type of reaction. However, they should be carefully analysed when comparing functionalisations produced using different reaction types.The authors acknowledge financial support from the Spanish government (project PID2020-113080RB-I00) and the Junta de Comunidades de Castilla-La Mancha (project SBPLY/21/180501/000135/1). This study forms part of the Advanced Materials program and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by the Junta de Comunidades de Castilla-La Mancha. The work at the University of Malaga was funded by the MICINN (PID202-139548NB-I00) and by the Junta de Andalucia (P18-FR-4559) projects. The authors thankfully acknowledge the computer resources, technical expertise, and assistance provided by the SCBI (Supercomputing and Bioinformatics) centre of the University of Malaga. M. I. L. acknowledges her Juan de la Cierva Incorporacion grant (IJC 2018-035355-I) funded by MCIN/AEI/10.13039/501100011033. Funded with Aid for First Research Projects (PAID-06-22), Vice-rectorate for Research of the Universitat Politecnica de Valencia (UPV).Lucío, MI.; Giacalone, F.; La Parola, V.; Gámez-Valenzuela, S.; Muñoz-Alba, F.; Ruiz Delgado, MC.; Herrero, MA.... (2023). A Prato Tour on Carbon Nanotubes: Raman Insights. Chemistry - A European Journal. 29. https://doi.org/10.1002/chem.2023024762

Microwave-assisted functionalization of carbon nanohorns with oligothiophene units with SERS activity

[EN] Carbon nanohorns have been functionalized with oligothiophene unitsviathe 1,3-dipolar cycloaddition reaction under microwave irradiation and solvent-free conditions. A dramatic Raman enhancement was found for one of the synthesized derivatives. Experimental andin silicostudies helped to understand the enhancement, attributed to the modification of electromagnetic fields upon functionalization at the tip of the nanostructures.This work was supported by the Iberdrola Foundation (CONV120313), the Spanish Ministerio de Economia y Competitividad (CTQ2017-88158-R), the Junta de Comunidades de Castilla-La Mancha (SBPLY/17/180501/000204) and FEDER-JCCM (UNCM13-1E-1663). The work at the University of Malaga was funded by the MICINN (PID2019-110305GB-I00) and Junta de Andalucia (P09FQM-4708) projects. M. I. L. acknowledges MINECO for her Juan de la Cierva-formacion grant (FJCI-2016-29593). The authors acknowledge the computer resources, technical expertise, and assistance provided by the Supercomputing and Bioinformatics centre of the University of Malaga.Iglesias, D.; Guerra, J.; Lucío, MI.; González-Cano, RC.; Lopez Navarrete, JT.; Ruiz Delgado, MC.; Vázquez, E.... (2020). Microwave-assisted functionalization of carbon nanohorns with oligothiophene units with SERS activity. Chemical Communications. 56(63):8948-8951. https://doi.org/10.1039/D0CC03496G89488951566

Tuning the Diradical Character of Indolocarbazoles: Impact of Structural Isomerism and Substitution Position

In this study, a set of 10 positional indolocarbazole (ICz) isomers substituted with dicyanomethylene groups connected via para or meta positions are computationally investigated with the aim of exploring the efficiency of structural isomerism and substitution position in controlling their optical and electronic properties. Unrestricted density functional theory (DFT), a spin-flip time-dependent DFT approach, and the multireference CASSCF/NEVPT2 method have been applied to correlate the diradical character with the energetic trends (i.e., singlet–triplet energy gaps). In addition, the nucleus-independent chemical shift together with ACID plots and Raman intensity calculations were used to strengthen the relationship between the diradical character and (anti)aromaticity. Our study reveals that the substitution pattern and structural isomerism represent a very effective way to tune the diradical properties in ICz-based systems with meta-substituted systems with a V-shaped structure displaying the largest diradical character. Thus, this work contributes to the elucidation of the challenging chemical reactivity and physical properties of diradicaloid systems, guiding experimental chemists to produce new molecules with desirable properties.Funding for open access charge: Univesidad de Málaga/CBUA. The work at the University of Málaga was funded by the MICINN (PID2019-110305GB-I00) and Junta de Andalucía (UMA18-FEDERJA-080, P09FQM-4708, and P18-FR-4559) projects. The authors thankfully acknowledge the computer resources, technical expertise, and assistance provided by the SCBI (Supercomputing and Bioinformatics) centre of the University of Málaga. The work at the University of Alicante was supported by the MICINN (PID2019-106114GB-I00). The work at the University of Bologna was supported by University of Bologna (RFO) funds

Quantum chemical DFT and spectroscopic UV-Vis-NIR analysis of a series of push-pull oligothiophenes end capped by amino-cyanovinyl groups

A series of push-pull chromophores built around thiophene-based -conjugating spacers and bearing various types of amino-donors and cyanovinyl-acceptors have been analyzed by means of UV-Vis- NIR spectroscopic measurements. Density functional theory (DFT) calculations have also been performed to help the assignment of the most relevant electronic features and to derive useful information about the molecular structure of these NLO-phores. The effects of the donor/acceptor substitution in the electronic and molecular properties of the -conjugated spacer have been addressed. The effectiveness of the intramolecular charge transfer (ICT) has also been tested as a function of the nature of the end groups (i.e., electron-donating or electron-withdrawing capabilities).Research at the University of Málaga was supported by the Ministerio de Educación y Ciencia (MEC) of Spain through project CTQ2006-14987-C02-01, and by the Junta de Andalucía for funding our FQM- 0159 scientific group. J.C. is grateful to the Ministerio de Ciencia y Tecnología of Spain for a Ramón y Cajal position of Chemistry at the University of Málaga. M.C.R.D. is also grateful to the Ministerio de Educación y Ciencia of Spain for a personal grant. The group at the University of Minho acknowledges the Foundation for Science and Technology (Portugal) for financial support through Centro de Química (UM) and through POCTI, FEDER (ref. POCTI/QUI/37816/2001). M. Manuela M. Raposo and A. Maurício C. Fonseca are also grateful to Professor G. Kirsch from University of Metz (France) for his collaboration

Carbazole and indolcarbazole-based systems: impact of the structural changes on the system properties

π-Conjugated diradical compounds, featuring unique unsaturated valences and radical centres in the ground state, are fundamentally important for understanding the nature of chemical bonds and have potential applications in material science [1] . During the last decade, there has been an increasing interest in the rationalization of how the structural changes stabilize (or destabilize) the diradical system. The tunability of the diradical character has been studied for different structural motifs such as the substitution pattern of lateral groups[2], the elongation of the conjugated core[3] or the molecular isomerism[4], among others. In this sense, we have recently reported an experimental/theoretical study of a family of carbazole-based diradicaloids with dicyanomethylene (DCM) groups incorporated via para (p-Cz and p-ICz) or meta positions (mCz and m-ICz) aiming to investigate how external stimuli impact on the molecular structure and supramolecular organization, and thus on the resulting optical and electronic properties. In addition, we theoretically investigate at the DFT level a set of ten indolocarbazole-based isomers substituted with DCM groups to disclose how their chemical reactivity and physical properties are affected by isomerism and different substitution pattern.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Plan Propio de Investigación de la UM