Quantitative wave function analysis for excited states of transition metal complexes

The character of an electronically excited state is one of the most important descriptors employed to discuss the photophysics and photochemistry of transition metal complexes. In transition metal complexes, the interaction between the metal and the different ligands gives rise to a rich variety of excited states, including metal-centered, intra-ligand, metal-to-ligand charge transfer, ligand-to-metal charge transfer, and ligand-to-ligand charge transfer states. Most often, these excited states are identified by considering the most important wave function excitation coefficients and inspecting visually the involved orbitals. This procedure is tedious, subjective, and imprecise. Instead, automatic and quantitative techniques for excited-state characterization are desirable. In this contribution we review the concept of charge transfer numbers---as implemented in the TheoDORE package---and show its wide applicability to characterize the excited states of transition metal complexes. Charge transfer numbers are a formal way to analyze an excited state in terms of electron transitions between groups of atoms based only on the well-defined transition density matrix. Its advantages are many: it can be fully automatized for many excited states, is objective and reproducible, and provides quantitative data useful for the discussion of trends or patterns. We also introduce a formalism for spin-orbit-mixed states and a method for statistical analysis of charge transfer numbers. The potential of this technique is demonstrated for a number of prototypical transition metal complexes containing Ir, Ru, and Re. Topics discussed include orbital delocalization between metal and carbonyl ligands, nonradiative decay through metal-centered states, effect of spin-orbit couplings on state character, and comparison among results obtained from different electronic structure methods.Comment: 47 pages, 19 figures, including supporting information (7 pages, 1 figure

Interstate Vibronic Coupling Constants Between Electronic Excited States for Complex Molecules

In the construction of diabatic vibronic Hamiltonians for quantum dynamics in the excited-state manifold of molecules, the coupling constants are often extracted solely from information on the excited-state energies. Here, a new protocol is applied to get access to the interstate vibronic coupling constants at the time-dependent density functional theory level through the overlap integrals between excited-state adiabatic auxiliary wavefunctions. We discuss the advantages of such method and its potential for future applications to address complex systems, in particular those where multiple electronic states are energetically closely lying and interact. As examples, we apply the protocol to the study of prototype rhenium carbonyl complexes [Re(CO)$_3$(N,N)(L)]$^{n+}$ for which non-adiabatic quantum dynamics within the linear vibronic coupling model and including spin-orbit coupling have been reported recently.Comment: 36 pages, 7 figures, 4 table

Energy-based descriptors for photo-catalytically active metal-organic framework discovery

Metal–organic frameworks (MOFs) consist of metal nodes that are connected by organic linkers. They are thus highly chemically tunable materials given the broad range of potential linkers and nodes that can be chosen for their synthesis. Their tunability has recently sparked interest in the development of new MOF photo-catalysts for energy-related applications such as hydrogen (H2) evolution and CO2 reduction. The sheer number of potentially synthesizable MOFs requires defining descriptors that allow prediction of their performance with this aim. Herein we propose a systematic computational protocol to determine two energy-based descriptors that are directly related to the performance of a MOF as a photocatalyst. These descriptors assess the UV-vis light absorption capability and the band energy alignment with respect to redox processes and/or co-catalyst energy levels. High-throughput screening based on cost-effective computations of these features is envisioned to aid the discovery of new promising photoactive systems

Use of water soluble extracts from ulva sp. by probiotics and fish bacterial pathogens

BACKGROUNDS The potential of seaweeds as dietary components is considered for a wide range of cultured fish species. In this context, Ulva is investigated as a good source of protein, minerals and vitamins. In addition, of probiotics are used to improve fish growth and modulate immune system and intestinal microbiota. To promote probiotics colonization and maintenance in the intestine, prebiotics are included in fish diets. Prebiotics are indigestible substrates used as energy sources for gastrointestinal microbiota, with a positive effect on the nutrition and health status of the host. In the present work, ability of selected probiotic and fish pathogen strains to use water soluble extracts from Ulva as nutrient source has been evaluated. MATERIALS AND METHODS Water-soluble extracts from Ulva sp. prepared by sonication of dehydrated samples were used to supplement minimum medium (M9). Probiotics and pathogens growth was evaluated based on the optical densities measured with a microplate reader. RESULTS AND CONCLUSIONS Probiotics were able to grow in minimum medium using water soluble extracts as nutrient source. On the other hand, P. damselae subsp. piscicida and V. harveyistrains were also able to grow with Ulvaextracts as nutrient source. However, incubation time to reach maximum growth was longer. Although Ulva extract may support growth of both probiotics and pathogen bacteria, faster growth of probiotics may help for the establishment of probiotic populations in the intestinal environment. In addition, beneficial effects on growth performance, gut microbiota, immunity and disease resistance of Ulva for Solea senegalensisare being studied. This work was funded by INIA, Ministerio de Economía y Competitividad and FEDER (RTA201400023 C0202).This work was funded by INIA, Ministerio de Economía y Competitividad and FEDER (RTA201400023 C0202).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Use of in-vivo induced antigen technology to identify bacterial genes expressed during Solea senegalensis infection with Photobacterium damselae subsp. piscicida

The marine fish pathogen Photobacterium damselae subsp. piscicida (Phdp) is responsible for important disease outbreaks affecting several fish species including flatfish Solea senegalensis (Kaup). Phdp is able to avoid host defences by invasion and intracellular survival in non-phagocytic cells, mainly epithelial cells. Virulence factors reported in Phdp include restricting complement-mediated activity, apoptosis of phagocytes caused by exotoxins secretion, iron acquisition mechanisms such as siderophores that enable the pathogen to obtain iron from transferrin and ability to bind haemin and antioxidant enzymatic activities capable to counteract superoxide radicals (Do Vale et al., 2005; Andreoni and Magnano, 2014). Commonly, genes expressed during pathogen infection are important for pathogenicity. In vivo-induced antigen technology (IVIAT) (Handfield et al., 2000) has been used to identify in vivo-induced genes using pooled sera from fish that have experienced photobacteriosis. Materials and methods Sera were obtained from surviving S. senegalensis specimens after sublethal infection with Phdp (Lg41/01) and subsequently pooled and adsorbed against in vitro grown Phdp Lg41/01 and Escherichia coli BL21 (DE3) cells and lysates according to Handfield et al. (2000). The efficiency of sera adsorption was evaluated based on the immunoreactivity after each adsorption step with whole and lysed Phdp cells grown in vitro. A genomic expression library of Phdp Lg41/01 was generated in E. coli BL21 (DE3) using pET-30 expression system (Novagen, San Diego, CA, USA). The expression library was probed with adsorbed and non-absorbed sera using immunoblot technique. Reactive clones of in vivo-induced and in vitro antigens were obtained, purified and their inserted DNA sequenced (Macrogen Europe, Amsterdam, The Netherlands). Nucleotide sequences were compared against the NCBI protein database using BLASTx. Results A progressive reduction in sera immunoreactivity against in vitro grown Phdp cells was detected after the adsorption rounds, especially after the first adsorption step. Thus, following adsorption steps substantially removed antibodies against in vitro expressed antigens and resulted in relative enrichment in antibodies recognizing in vivo expressed antigens. The library from Phdp Lg14/01 constructed in E. coli BL21 (DE3) consisted of approximately 6500 recombinants. A total of 117 clones were selected for their reactivity with pooled adsorbed and non-adsorbed sera from convalescent S. senegalensis specimens after a first round of screening. In a second screening, 14 out of 117 candidate clones showed positive reaction, among which two clones were clearly positive and two gave weak reaction against adsorbed sera. Predicted proteins codified by inserted sequences have intracellular and membrane cell location and are involved in virulence, synthesis of intermediary products, energy metabolism and gene replication. Inosine-5’-monophosphate dehydrogenase (IMPDH) and alkyl hydroperoxide reductase (AhpC) have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Iron/manganese superoxide dismutase (Fe/Mn-SOD) and alanyl-tRNA synthetase (AlaRS) proteins have also been identified, though with weak signal. Discussion and conclusion Identification of immunogenic bacterial proteins during Phdp infection is essential for understanding bacterial pathogenesis and development of effective vaccines. AhpC peroxidase activity has a protective role by reducing hydrogen peroxide, peroxynitrite and organic hydroperoxides. Immunization with AhpC conferred protection against Helicobacter pylori infection (O’Riordan et al., 2012). IMPDH catalyzes the conversion of products essential in de novo synthesis of guanine nucleotides. Adequate levels of purine nucleotides are critical for cell proliferation, nucleic acid replication, cell signaling and as a biochemical energy source. This gene is an important therapeutic target against bacterial diseases (Shu and Nair,2008). In conclusion, different genes expressed during Phdp infection in S. senegalensis have been identified. Among them, IMPDH and AhpC have been identified as in vivo induced antigens expressed during S. senegalensis infection with Phdp. Thus, they are likely to play a role in the virulence of Phdp. The antigenic character of these proteins makes them potential targets for the development of new vaccines. References Andreoni, F., and Magnani, M., 2014. Photobacteriosis: Prevention and Diagnosis. Journal of Immunology Research, 2014: 1-7. Do Vale, A., Silva, M.T., dos Santos, N.M., Nascimento, D.S., Reis Rodrigues, P., Costa Ramos, C., Ellis, A.E., and Azevedo, J.E., 2005. AIP56, a novel plasmid-encoded virulence factor of Photobacterium damselae subsp. piscicida with apoptogenic activity against sea bass macrophages and neutrophils. Molecular Microbiology, 58: 1025-1038. Handfield, M., Brady, L.J., Progulske-Fox, A., and Hillman, J.D., 2000. IVIAT: a novel method to identify microbial genes expressed specifically during human infections. Trends in Microbiology, 8: 336-339. O’Riordan A.A., Morales V.A., Mulligan L., Faheem N., Windle H.J., and Kelleher D.P., 2012. Alkyl hydroperoxide reductase: a candidate Helicobacter pylori vaccine. Vaccine, 30:3876-3884. Shu, Q., and Nair, V., 2008. Inosine monophosphate dehydrogenase (IMPDH) as a target in drug discovery. Medicinal Research Reviews, 28:219-232.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Lattice-solvent effects in the spin-crossover of an Fe(II)-based material. The key role of intermolecular interactions between solvent molecules

The spin transition of Fe(II) complexes is the subject of intensive synthetic and computational efforts. In this manuscript, we analyze the spin crossover (SCO) of [Fe(Edpsp)(2)](2+) (1), which features a spin transition depending on the cocrystallizing solvent molecules. Whereas the use of acetone results in a hysteretic spin transition at similar to 170 K, the use of propylene carbonate (PC) results in a permanent diamagnetic signal up to 300 K. By means of DFT+U+D2 calculations in the solid state of the material, we unravel the reasons for such different behavior. Our results allow us to ascribe the relatively low transition temperature of 1(BF4)(2.) acetone to the distorted arrangement of the SCO molecules in the low-spin state of the material. In turn, intermolecular interactions play the primary role in the case of 1(BF4)(2).2PC. In particular, we found that solvent-solvent interactions actively promote the stability of the low-spin state due to the formation of PC dimers. These dimers would appear at larger distances in the high-spin phase, with the subsequent loss of phase stability. This is yet another proof of how subtle is the spin transition phenomenon in Fe(II)-based architectures

Asociación entre estilo de vida saludable y adherencia a fármacos antihipertensivos e hipolipemiantes en los trabajadores del Aragón Workers’ Health Study

Estudio observacional descriptivo basado en los trabajadores de la cohorte AWHS, con la finalidad de analizar la asociación entre la presencia de estilos de vida saludables y la adherencia terapéutica en trabajadores que inician tratamiento con fármacos antihipertensivos e hipolipemiantes. Así mismo, se describieron los hábitos y estilo de vida de los sujetos incluidos en el estudio, se midió la adherencia terapéutica separadamente para los fármacos estudiados y se analizaron los factores de tipo sociodemográfico, antropométrico, laboral y clínico que podrían influir en la asociación de la adherencia terapéutica y la adherencia a un estilo de vida saludable.<br /

Three Redox States of a Diradical Acceptor−Donor−Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

The diradical acceptor–donor–acceptor triad 1••, based on two polychlorotriphenylmethyl (PTM) radicals connected through a tetrathiafulvalene(TTF)–vinylene bridge, has been synthesized. The generation of the mixed-valence radical anion, 1•–, and triradical cation species, 1•••+, obtained upon electrochemical reduction and oxidation, respectively, was monitored by optical and ESR spectroscopy. Interestingly, the modification of electron delocalization and magnetic coupling was observed when the charged species were generated and the changes have been rationalized by theoretical calculations.This work was supported by the DGI grant (CTQ2013-40480- R), the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), and the Generalitat de Catalunya (grant 2014-SGR-17). ICMAB acknowledges support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496). M.S. is enrolled in the Material Science Ph.D. program of UAB and is grateful to MEC for a FPU predoctoral grant. S.V. and M.F. are thankful to the LabEx-Chemistry of Complex Systems for postdoctoral grants (ANR-10-LABX-0026CSC) and to the regional High-Performance Computing (HPC) center in Strasbourg for computational resources. We thank Amable Bernabé for the MALDI spectroscopy.Peer reviewe

Interstate vibronic coupling constants between electronic excited states for complex molecules

In the construction of diabatic vibronic Hamiltonians for quantum dynamics in the excited-state manifold of molecules, the coupling constants are often extracted solely from information on the excited-state energies. Here, a new protocol is applied to get access to the interstate vibronic coupling constants at the time-dependent density functional theory level through the overlap integrals between excited-state adiabatic auxiliary wavefunctions. We discuss the advantages of such method and its potential for future applications to address complex systems, in particular, those where multiple electronic states are energetically closely lying and interact. We apply the protocol to the study of prototype rhenium carbonyl complexes [Re(CO)3(N,N)(L)]n+ for which non-adiabatic quantum dynamics within the linear vibronic coupling model and including spin-orbit coupling have been reported recently

Pitfalls on evaluating pair exchange interactions for modelling molecule-based magnetism

Molecule-based magnetism is a solid-state property that results from the microscopic interaction between magnetic centres or radicals. The observed magnetic response is due to unpaired electrons whose coupling leads to a particular magnetic topology. Therefore, to understand the magnetic response of a given molecule-based magnet and reproduce the available experimental magnetic properties by means of statistical mechanics, one has to be able to determine the value of the J(AB) magnetic exchange coupling between radicals. The calculation of J(AB) is thus a key point for modelling molecule-based magnetism. In this Perspectives article, we will build upon our experience in modelling molecular magnetism to point out some pitfalls on evaluating J(AB) couplings. Special attention must be paid to the cluster models used to evaluate J(AB), which should account for cooperative effects among J(AB) interactions and also consider the environment (counterions, hydrogen bonding) of the two radicals whose interaction has to be evaluated. It will be also necessary to assess whether a DFT-based or a wavefunction-based method is best to study a given radical. Finally, in addition to model and method, the J(AB) couplings have to be able to adapt to changes in the magnetic topology due to thermal fluctuations. Therefore, it is most important to appraise in which systems molecular dynamics simulations would be required. Given the large number of issues one must tackle when choosing the correct model and method to evaluate J(AB) interactions for modelling magnetic properties in molecule-based materials, the "human factor" is a must to cross-examine and challenge computations before trusting any result.MD, JRA, and JJN acknowledge financial support from MINECO (CTQ2017-87773-P/AEI/FEDER, UE), Spanish Structures Excellence Maria de Maeztu program (MDM-2017-0767), and Catalan DURSI (2017SGR348)