2D-Delocalized vs Confined Diradicals

Resumen de la comunicación oral seleccionadaDiradicals are beautiful chemical objects where the more basic and intricate aspects of the chemical bonding are revealed.1 Not this being important enough, nowadays, diradical-based substrates are becoming very appealing for new organic electronic applications. We focus here in conjugated organic diradicals formed by competition between non-aromatic quinoidal structures and their canonical aromatic forms. How this quinoidal(closed-shell)-vs-aromatic(open-shell) energetic balance producing the diradical is affected by several situations has been our objective in the last few years.2 Now, we focusses on how the properties of diradicals are influenced when several diradical canonical forms are available in such a way that create a 2D (i.e., bidimensional) electron delocalization surface in which the diradical substructures are in cross-conjugation mode producing the curious effect of diradical confinement.3 Herein, the diradical molecular properties of compound 1 in Figure 1 will be discussed in connection with 2D delocalization, cross-conjugation and surface confinement. 1. Rajca, A., Chem. Rev., 1994, 94, 871; Abe, M., Chem. Rev. 2013, 113, 7011. 2. Zeng, Z.; X. Shi, L.; Chi, C.; Casado, J.; Wu, J. Chem. Soc. Rev. 2015, 44, 6578. 3. Yuan, D.; Huang, D.; Medina Rivero, S.; Carreras, A.; Zhang, C.; Zou, Y.; Jiao, X.; McNeill, C.R.; Zhu, X.; Di, C.; Zhu, D.; Casanova, D.; Casado, J. CHEM, 2019, accepted.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

KnowVolution: Redesigning enzymes for innovations

Directed evolution has matured in academia and industry to a routinely applied algorithm to tailor enzyme properties1 to match especially demands in synthesis and material science. In order to free directed enzyme evolution from methodological restraints and to efficiently explore its potential, one has to balance time requirements for a directed evolution campaign, the number of generated enzyme variants, and limitations in state of the art screening technologies. For instance, saturation mutagenesis of six amino acid positions in an enzyme, which usually consists of \u3e50 amino acids, yields 64 million (206) different enzyme variants. The latter represents the upper throughput for activity-based screening systems2. In essence, protein engineers have to accept that they will not be able to sample through the theoretical obtainable sequence space of enzyme variants and smarter strategies are required for efficient directed enzyme evolution. The KnowVolution (Knowledge gaining direct evolution)3 approach represents such a directed evolution 2.0 strategy, which identifies in four phase with limited screening efforts, significantly improved enzymes variants and ensures a molecular understanding of improved enzyme properties. Three out of six in a review reported KnowVolution campaigns3 were commercialized by industrial partners; thereby limiting the number of substitutions turned out to be a key prerequisite for maintaining thermal resistance, process stability and selectivity. In addition, directed enzyme evolution by random mutagenesis will be compared to improvements that are obtainable with a variant library that contains all natural possible diversity with ONE amino acid exchange (SSM library)4. The comparison of 3000 mutations from random mutagenesis libraries with the SSM library taught us how many of the natural occurring beneficial positions are obtainable or unobtainable by state of art methodologies in directed evolution and provided first insights on general design principles to improve enzymatic resistance in organic cosolvents4 and ionic liquids4. References: (1) a.Shivange, A. V., Marienhagen, J., Mundhada, H., Schenk, A., Schwaneberg, U. (2009). Curr. Opin. Chem. Biol. 13, 19. b.Ruff, A. J., Dennig, A., Schwaneberg, U. (2013). FEBS J. 280, 2961. (2) a.Körfer, G., Pitzler, C., Vojcic, L., Martinez, R., Schwaneberg, U. (2016). Scientific Reports, 6, 1-12. b.Lülsdorf, N., Pitzler, C., Biggel, M., Martinez, R., Vojcic, L., Schwaneberg, U. (2015). Chem. Commun. 51, 8679. c.Ruff, A. J., Dennig, A., Wirtz, G., Blanusa, M., Schwaneberg, U. (2012). ACS Catalysis 2, 2724. (3) Cheng, F., Zhu, L., Schwaneberg, U. (2015). Chem. Commun. 51, 9760. a.Zhao, J., Frauenkron-Machedjou, V. J., Kardashliev, T., Ruff, A. J., Zhu, L., Bocola, M., Schwaneberg, U. (2017). Appl. Microbiol. Biotechnol., 2017, DOI: 10.1007/s00253-016-8035-1. b.Frauenkron-Machedjou, V. J., Fulton, A., Zhu, L., Bocola, M., Zhu, L., Jaeger, K.-E., Schwaneberg, U. (2015). ChemBioChem, 16, 937-945. c.Zhao, J., Kardashliev, T., Ruff, A. J., Bocola, M., Schwaneberg, U. (2014). Biotechnol. Bioeng. 111, 2380

Retracted: Inhibition of Corneal Neovascularization by Hydrazinocurcumin

This article previously published in Volume 15 Issue 2 of this journal in February 2016 has been retracted in line with the guidelines from the Committee on Publication Ethics (COPE, http://publicationethics.org/resources/guidelines)Retracted: Zhan W, Zhu J, Zhang Y. Inhibition of corneal neovascularization by hydrazinecurcumin. Trop J Pharm Res 2016; 15(2):349-354 doi: http://dx.doi.org/10.4314/tjpr.v15i2.18

Transient Absorption and Raman Spectroscopies in Organic Electronics

Raman spectroscopy has proved to be a very valuable tool for characterization in a large number of research fields, both biological, chemical and material sciences.[1] In the last decades, organic electronics has broken out as a real alternative to conventional electronics, based on inorganic materials. However, in order to advance significantly in this field of research is paramount the full characterization of electronic devices, going from the individual molecule to the system as a whole. Moreover, the study of photophysical and photochemical processes crosses the interest of many fields of research in physics, chemistry and biology. Among the experimental approaches developed for this purpose, the advent of ultrafast transient absorption spectroscopy has become a powerful and widely used method.[2,3] This pump-probe technique is a popular means of studying photophysics, because of its versatile time resolution and its ease of comparison with ground-state absorption spectra. In this communication, I will present the basic principles of transient absorption spectroscopy, along with some examples where its combination with Raman spectroscopy allows the great characterization of organic molecules with potential applications in organic electronics.[4,5] References [1] H. Schulz, M. Baranska, R. Baranski. Biopolymers 2005, 77, 212 - 221. [2] U. Megerle, I. Pugliesi, C. Schriever, C.F. Sailer, E. Riedle. Appl. Phys. B, 2009, 96, 215 - 231. [3] R. Berera, R. van Grondelle, J.T.M. Kennis. Photosynth. Res. 2009, 101, 105 - 118. [4] E. Anaya-Plaza, M. Moreno Oliva, A. Kunzmann, C. Romero-Nieto, R.D. Costa, A. de la Escosura, D.M. Guldi, T. Torres. Adv. Funct. Mater. 2015, 25, 7418 - 7427. [5] F. Liu, G.L. Espejo, S. Qiu, M. Moreno Oliva, J. Pina, J.S. Seixas de Melo, J. Casado, X. Zhu. J. Am. Chem. Soc. 2015, 137, 10357 - 10366.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Dielectric relaxation of manganese modified Bi6Fe2Ti3O18 Aurivillius-type ceramics

The five-layer Aurivillius type structures with the general chemical formula Bi5Fe2-xMnxTi3O18, where x = 0, 0.6, 1.2 have been synthesized and tested. The SEM studies showed a significant increase in grain size in the manganese-modified Aurivillius type ceramic material (for x= 1.2). The increase in the amount of manganese ions (Mn3+) affects the decrease in the temperature at which the relaxation processes take place. Namely from 525 K (1 kHz) and 725 K (1 MHz) for BFT sample (x= 0) to 355 K (1 kHz) and 565 K (1 MHz) for BFM12T sample (x= 1.2). Using the Arrhenius’s law and the Vogel-Fulcher’s relationship the activation energy (Ea) and the relaxation time have been calculated. The value of Ea increases with the increase of the Mn amount from 0.737 eV (for x= 0) to 0.915 eV (for x= 1.2).[1] B. Aurivillius, Arkiv Kemi 1 463, 499-463 (1949). [2] E.C. Subbarao, J. Am. Ceram. Soc. 45,166 (1962). [3] H. Schmid, J. Phys.: Condens. Matter. 20, 434201 (2008). [4] D. Khomskii, Physics 2, 20 (2009). [5] D. Bochenek, J. Alloy. Compd. 504, 508-513 (2010). [6] M. Bibes, A. Barthélémy, Nat. Mater. 7, 425-426 (2008). [7] Z. Wang, Y. Zhang, Y. Wang, Y. Li, H. Luo, J. Li, D. Viehland, ACS Nano 8(8), 7793-7800 (2014). [8] J.A. Bartkowska, J. Dercz, J. Exp. Theor. Phys. 117(5), 875-878 (2013). [9] M. Villegas, T. Jardiel, A.C. Caballero, J.F. Fernandez, J. Electroceram. 13, 543-548 (2004). [10] Zuo X, Yang J, Yuan B, Song D, Tang X, Zhang K, Zhu X, Song W, Dai J, Sun Y, RSC Adv. 4, 46704 (2014). [11] W. Bai, G. Chen, J.Y. Zhu, J. Yang, T. Lin, X.J. Meng, X.D. Tang, C.G. Duan, J.H. Chu, Appl. Phys. Lett. 100, 0829021 (2012). [12] K. Tang, W. Bai, J. Liu, J. Yang, Y. Zhang, C.G. Duana, X. Tanga, J. Chu, Ceram. Inter. 41, S185-S190 (2015). [13] X.Y. Mao, W. Wang, X.B. Chen, Sol. St. Comm. 147(5-6), 186-189 (2008). [14] H. Yan, H. Zhang, R. Ubic, M. Reece, J. Liu, Z. Shen, J. Mater. Sci. Mater. Electron. 17, 657-661 (2006). [15] H.S. Shulman, D. Damjanovic, Setter N, J. Am. Ceram. Soc. 83 (3), 528-532 (2000). [16] A. L. Kholkin, M. Avdeev, M. E. V. Costa, J. L. Baptista, Appl. Phys. Lett. 79, 662-664 (2001)