Accelerating FIU’s science research and education towards discovery and innovation by leveraging FIU’s Science DMZ

Research faculty and their students are spending too much time on data management issues related to the transfer of data between networks. As the campus cyberinfrastructure increases data production, the transport capacity of the network must increase proportionally to deliver the data to the High-Performance Computing centers for analysis. This work presents the experience of a research project in implementing Science DMZ at Florida International University, which added six researchers and their laboratories to the Science Network and Science DMZ. The study applied a qualitative approach to assessing the researcher’s science workflows in order to create a Science DMZ implementation plan and followed the Energy Sciences Network implementation guide

Photophysical and Photochemical Studies of Tricarbonyl Rhenium(I) N-Heterocyclic Carbene Complexes Containing Azide and Triazolate Ligands

Rhenium(I) N-heterocyclic carbene (NHC) complexes of the type fac-[Re(CO)3(NHC)L] with either azide or triazolate ancillary ligands L and pyridyl or pyrimidyl substituted imidazolyl units have been prepared and structurally characterised, and their photophysical and photochemical properties studied. All of the complexes exhibit phosphorescent emission from triplet metal-to-ligand (3MCLT) excited states, typical of tricarbonyl Re(I) complexes, with the triazolate bound complexes having higher quantum yields and longer decay lifetimes compared to the azide bound complexes. The complexes containing pyridyl substituted imidazolyl units are photoreactive when dissolved in acetonitrile and undergo photochemical CO dissociation, the rate of which is significantly greater in the azide cf. triazolate complex. The photochemical mechanism of the azide/pyridyl complex was analysed and appears to give the same products, albeit with different ratios, to previously reported complexes where L is a halide. A reaction mechanism is proposed

Mitochondria Targeting with Luminescent Rhenium(I) Complexes

Two new neutral fac-[Re(CO)3(phen)L] compounds (1,2), with phen = 1,10-phenanthroline and L = O2C(CH2)5CH3 or O2C(CH2)4C≡CH, were synthetized in one-pot procedures from fac-[Re(CO)3(phen)Cl] and the corresponding carboxylic acids, and were fully characterized by IR and UV-Vis absorption spectroscopy, 1H- and 13C-NMR, mass spectrometry and X-ray crystallography. The compounds, which display orange luminescence, were used as probes for living cancer HeLa cell staining. Confocal microscopy revealed accumulation of both dyes in mitochondria. To investigate the mechanism of mitochondrial staining, a new non-emissive compound, fac-[Re(CO)3(phen)L], with L = O2C(CH2)3((C5H5)Fe(C5H4), i.e., containing a ferrocenyl moiety, was synthetized and characterized (3). 3 shows the same mitochondrial accumulation pattern as 1 and 2. Emission of 3 can only be possible when ferrocene-containing ligand dissociates from the metal center to produce a species containing the luminescent fac­[Re(CO)3(phen)]+ core. The release of ligands from the Re center was verified in vitro through the conjugation with model proteins. These findings suggest that the mitochondria accumulation of compounds 1–3 is due to the formation of luminescent fac-[Re(CO)3(phen)]+ products, which react with cellular matrix molecules giving secondary products and are uptaken into the negatively charged mitochondrial membranes. Thus, reported compounds feature a rare dissociation-driven mechanism of action with great potential for biological applications.The X-ray single-crystal diffraction studies were carried out at the Biological and Chemical Research Centre, University of Warsaw, established within the project co-financed by European Union from the European Regional Development Fund under the Operational Programme ‘Innovative Economy’, 2007–2013. This study was also supported by the National Science Centre Poland MAESTRO grant-DEC-2012/04/A/ST5/00609 (D.T. and K.W.), which enabled the X-ray structural analysis to be performed. RC thanks the European Research Council (ERC) for support in the framework of the MSCA RISE Project no. 645628

Theoretical investigation of the electronic structure of Fe(II) complexes at spin-state transitions

The electronic structure relevant to low spin (LS)high spin (HS) transitions in Fe(II) coordination compounds with a FeN6 core are studied. The selected [Fe(tz)6]2+(1) (tz=1H-tetrazole), [Fe(bipy)3]2+(2) (bipy=2,2’-bipyridine) and [Fe(terpy)2]2+ (3) (terpy=2,2’:6’,2’’-terpyridine) complexes have been actively studied experimentally, and with their respective mono-, bi-, and tridentate ligands, they constitute a comprehensive set for theoretical case studies. The methods in this work include density functional theory (DFT), time-dependent DFT (TD-DFT) and multiconfigurational second order perturbation theory (CASPT2). We determine the structural parameters as well as the energy splitting of the LS-HS states (ΔEHL) applying the above methods, and comparing their performance. We also determine the potential energy curves representing the ground and low-energy excited singlet, triplet, and quintet d6 states along the mode(s) that connect the LS and HS states. The results indicate that while DFT is well suited for the prediction of structural parameters, an accurate multiconfigurational approach is essential for the quantitative determination of ΔEHL. In addition, a good qualitative agreement is found between the TD-DFT and CASPT2 potential energy curves. Although the TD-DFT results might differ in some respect (in our case, we found a discrepancy at the triplet states), our results suggest that this approach, with due care, is very promising as an alternative for the very expensive CASPT2 method. Finally, the two dimensional (2D) potential energy surfaces above the plane spanned by the two relevant configuration coordinates in [Fe(terpy)2]2+ were computed both at the DFT and CASPT2 levels. These 2D surfaces indicate that the singlet-triplet and triplet-quintet states are separated along different coordinates, i.e. different vibration modes. Our results confirm that in contrast to the case of complexes with mono- and bidentate ligands, the singlet-quintet transitions in [Fe(terpy)2]2+ cannot be described using a single configuration coordinate

Bio-geochemical Factors that Affect RDX Degradation

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a secondary high explosive that has been identified as a contaminant of concern in groundwater and soil as a result of military training activities (Wani et al., 2002). Remediation technologies that have been proposed for use on these training ranges include in situ techniques. An obstacle to using in situ approaches for the treatment of RDX contaminated soils and groundwater is the lack of information concerning the biogeochemical factors that influence transformation. This research compares paired (biotic and poised abiotic systems) RDX degradation experiments in which Eh-pH conditions conducive to RDX degradation were established. Degradation of RDX under iron-reducing conditions was studied in biological and chemical systems. The redox conditions created by the biological systems were simulated by poised chemical systems in order to compare RDX transformation. The poised chemical systems used an iron-ligand complex to achieve the necessary Eh values for RDX degradation. RDX degraded in both biological and chemical systems and final reaction solutions from both systems were analyzed to determine which degradation pathway was followed. The results from this effort will expand the basic knowledge of energetic transformation over a range of biologically-induced conditions, by isolation of enzymatic pathways from abiotic redox mechanisms

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