Cyclic Triindoles and Tetraindoles: Substituent and Symmetry Effects on their Structural and Electronic Characteristics

During the last decade heptacyclic 10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (triindole) has been extensively studied as a new π-conjugated platform in the construction of self-assembling materials for optoelectronics. Specially remarkably is the record hole mobility values determined on triindole liquid crystals.1 In order to facilitate the design of new materials on a molecular basis and establish clear guidelines to fine tuning electronic parameters, we have recently synthesized new triindole and tetraindole-based systems.2-3 Our joint experimental and theoretical investigation shows that N-substitution, symmetry lowering of the platform, and insertion of π-spacers in extended dimers strongly impact on the fundamental electronic properties of triindoles.2 In addition, saddle-shaped tetraindoles are found to be an interesting 3D rigid scaffold to obtain electroactive molecules with increased dimensionality.3 We hope that this study can not only advance useful structure-property relationships of conjugated indole-based systems but also guide the design of new materials with potential applications in organic electronics.References 1. E.M. García-Frutos, U.K. Pandey, R. Termine, A. Omenat, J. Barberá, J.L. Serrano, A. Golemme, B. Gómez-Lor, Angew. Chem. Int. Ed. 2011, 50, 7399 2. a) C. Ruiz, J.T. López Navarrete, M.C.Ruiz Delgado, B. Gómez-Lor, Org. Lett. 2015, 17, 2258−2261. b) C. Ruiz, E.M. García-Frutos, D.A. da Silva Filho, J.T. López Navarrete, M.C. Ruiz Delgado, and B. Gómez-Lor, J. Phys. Chem. C 2014, 118, 5470−5477 3. C. Ruiz, A. Monge, E. Gutiérrez-Puebla, I. Alkorta, J. Elguero, J. T. López Navarrete, M.C. Ruiz Delgado and B. Gómez-Lor, submittedUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Theoretical study of Covalent Organic Frameworks based on C3-symmetric Central Cores

In recent years, the design and synthesis of COFs (covalent organic frameworks) has been deeply investigated. These materials are constructed from the union of different covalently linked conjugated platforms and they have a wide range of analytical applications, such as adsorption and / or separation of certain compounds, catalysis or identification of analytes, among others.1 On the other hand, the π-conjugated nature of these systems together with their extended 3D nature make them excellent candidates to be used in organic electronics.2 Recently, in collaboration with the group of Dr. Berta Gómez-Lor, we have studied the electronic and optical properties of four new porous truxene-based polymers.3 The results of this work opens the door to the control of the degree of π-conjugation and therefore to the optoelectronic properties of these materials (i.e., their potential as nitroaromatic compound sensors) through the substitution position of the truxene units. Here we propose to expand this study to COFs (Figure 1) derived from platforms with C3 symmetry based not only on truxene (X=C) but also on triindole (X=N) and truxenone (X=CO) units by means of periodic DFT-calculations (see Figure 1). Specifically, we study how the different structural modifications affect the intra- and intermolecular properties of the systems for their subsequent synthesis and real application in organic electronic devices.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

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

Donor-acceptor truxene-based porous polymers: synthesis, optoelectronic characterization and defense-related applications

Funding for open Access charge: Universidad de Málaga / CBUA. This research was funded by MICINN/AEI/ 10.13039/501100011033 (project PID2022-139548NB-I00, PID2019-104125RB-I00, and PID2020-112590GB-C22) and by Junta de Andalucía (P09FQM-4708 and P18-FR-4559). N.M.-G. and S.G.-V. contributed equally to this work. The authors would like to thank the computer resources, technical expertise and assistance provided by the SCBI (Supercomputing and Bioinformatics) center and the vibrational spectroscopy (EVI) lab of the Research Central Services (SCAI) of the University of MálagaFour donor-acceptor (D-A) polymers are synthesized by combining two different electron donors (truxene and its more electron rich triaza analogue, triindole) with an electron-deficient monomer (benzothiadiazole) through two different positions (2,7,13 or 3,8,13) and their optoelectronic properties are studied by theoretical and experimental methods. One of the polymers exhibits remarkable sensing capabilities for explosive nitraoaromatics while another demonstrated efficient photocatalytic activity in the aerobic sulfoxidation of the sulfur mustard simulant 2-chloro-ethyl ethyl sulfide (MGS) sulfoxidation. These results highlight their potential applications in defense-related areas. Moreover, the structure-performance relationships observed among the four polymers have enabled us to deepen the understanding of the mechanisms underlying the performance of these polymers in the aforementioned applications, thereby providing valuable insights to further improve their properties

Semiconducting pi-extended discotic liquid-crystalline triindoles: studying their FET vs. SCLC mobilities

The field of organic electronics has experienced a vast development in the last few years, having the first generation of devices based in this technology already reached the market. Advances achieved in this field have been associated with the research of organic semiconductors able to transport charge carriers with a high mobility. However, finding organic semiconductors with the right balance between mobility and processability is still a challenge in the area. In this context, discotic liquid crystals, constituted by an aromatic central core surrounded by flexible alkyl tails, are among the most promising new candidates. Triindoles have been widely studied as a π-conjugated platforms in the construction of high mobility semiconducting liquid crystals. Three-fold oxidative cyclodehydrogenation of hexaphenyltriindole renders the significantly enlarged aromatic core, with structural characteristics of both triphenylene moieties and triindole. In this π-extended discotic core, the attachment of three flexible alkyl chains to the nitrogen atoms is sufficient to induce mesomorphism. The ratio of conducting versus isolating fraction is impressively enhanced when comparing to triindole liquid crystals, not only by enlarging the size of the central core but also by reducing the amount of isolating peripheral chains. In this presentation the electrical properties of the aforementioned semiconductor have been analyzed by applying two different methods: space-charge limited current (SCLC) measurements in a diode-like structure and field effect mobility measurements in a thin film transistor device. The mobility found on a diode type device is higher than that determined on thin film transistors, which can be understood by the high tendency of large π-conjugated molecules to deposit on surfaces with their extended core parallel to the substrate. This is demonstrated with a full analysis of the active layer of the thin film transistor, in order to analyze the molecular orientation in the semiconductor-dielectric interface, via Surface Enhanced Raman Spectroscopy (SERS). The observation of field effect behavior in a discotic liquid crystal processed by simple drop-casing suggests an increased dimensionality of charge transport by facilitating hopping between neighboring columns as a result of the large conducting/isolating ratio found in this discotic platform. Density Functional Theory (DFT) calculations have been performed in order to enlighten with more detail the charge-transport parameters at a molecular level.Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tec

Tunable emission in dye-doped truxene-based organogels through RET

Organic systems comprising a truxene-based organogel doped with an organic dye have been fabricated and their photophysical properties examined in the search for an organic matrix with tunable luminescent properties. The addition of the organic dopant has been observed to introduce changes in the morphology of the gel which alters the ratio between monomer and excimer species. Further, the luminescent properties of the doped organogel have been studied and their evolution with dopant concentration explained in terms of resonant energy transfer between the excimer species (acting as a donor) and the organic dopant (acceptor). The interplay between blue, green and red emission bands associated with monomers, excimers and organic dopants allows tuning the luminescence of the system within the visible region reaching white light emission under certain conditions. The origin of the energy transfer is found to be the aggregation of the molecules upon solvent evaporation, the more stable xerogel phase being the extreme case which constitutes a technologically relevant approach where solvent evaporation is not an issue.Peer reviewe

Electroactive C3 symmetric discotic liquid-crystalline triindoles

3 pages, 2 figures, 1 table, 2 schemes.Discotic liquid crystals based on triindole, a novel redox active central core, have been synthesized and their mesomorphic behaviour investigated.Financial support from the MEC (CTQ2004-02865/BQU), the CAM (Project 200580M133), the CICYT-Spain (MAT2003- 07806-C01), FEDER (EU) and DGA is gratefully acknowledged.Peer reviewe

Utilisation d'un composé fluorescent en tant que composant d'encre de sécurité et encre de sécurité

[EN] The present invention relates to the use of a fluorescent compound of formula (I), the emission frequency of which varies in response to different external stimuli, as a security ink component. The invention also relates to the security ink comprising said compound.[ES] La presente invención se refiere al uso del compuesto fluorescente de fórmula (I), cuya frecuencia de emisión varía en respuesta a distintos estímulos externos, como componente de tinta de seguridad. La presente invención también se refiere a la tinta de seguridad que comprende dicho compuesto.[FR] La présente invention se rapporte à l'utilisation du composé fluorescent de formule (I), dont la fréquence d'émission varie en réponse à différents stimuli externe, comme constituant d'encre de sécurité. La présente invention concerne également l'encre de sécurité qui comprend ledit composé.Peer reviewedConsejo Superior de Investigaciones CientíficasA1 Solicitud de patente con informe sobre el estado de la técnic

Use of a fluorescent compound as a security ink component and security ink

[ES] Uso de un compuesto fluorescente como componente de tinta de seguridad y tinta de seguridad. La presente invención se refiere al uso del compuesto fluorescente de fórmula (I), cuya frecuencia de emisión varía en respuesta a distintos estímulos externos, como componente de tinta de seguridad. La presente invención también se refiere a la tinta de seguridad que comprende dicho compuesto.[EN] Use of a fluorescent compound as a component of security ink and security ink. The present invention refers to the use of the fluorescent compound of formula (I), whose emission frequency varies in response to different external stimuli, as a security ink component. The present invention also relates to the security ink comprising said compound.Peer reviewedConsejo Superior de Investigaciones CientíficasA1 Solicitud de patente con informe sobre el estado de la técnic

Use of a fluorescent compound as a security ink component and security ink

[ES] Uso de un compuesto fluorescente como componente de tinta de seguridad y tinta de seguridad. La presente invención se refiere al uso del compuesto fluorescente de fórmula (I), cuya frecuencia de emisión varía en respuesta a distintos estímulos externos, como componente de tinta de seguridad. La presente invención también se refiere a la tinta de seguridad que comprende dicho compuesto.[EN] Use of a fluorescent compound as a component of security ink and security ink. The present invention refers to the use of the fluorescent compound of formula (I), whose emission frequency varies in response to different external stimuli, as a security ink component. The present invention also relates to the security ink comprising said compound.Peer reviewedConsejo Superior de Investigaciones CientíficasB2 Patente con examen previ