SOLVING SIMPLE ORGANOMETALLIC STRUCTURES SOLELY FROM X-RAY-POWDER DIFFRACTION DATA - THE CASE OF POLYMERIC [(RU(CO)4)N]

The crystal and molecular structure of [Ru(CO)4n] has been determined solely from X-ray powder diffraction data using standard laboratory equipment and refined with a (modified) Rietveld procedure. The compound crystallizes in the orthorhombic space group Ibam, with a = 14.147(4), b = 7.060(2) and c = 5.720(1) angstrom, Z = 4; the final refinement (19 variables) converged to R(p') R(wp) and R(Bragg) of 0.077, 0.102 and 0.025, respectively, for 4001 data collected at room temperature in the 5-85-degrees (2theta) range. The structure, which consists of a polymeric stack of staggered trans-D4h Ru(CO)4 fragments separated by a Ru-Ru contact of 2.860(1) angstrom, is the first polymeric binary metal carbonyl compound so far characterized. Strain and particle-size broadening effects have been observed, and the microstructural properties of the compound are discussed

THE MULTIPHASE NATURE OF THE CU(PZ) AND AG(PZ) (HPZ=PYRAZOLE) SYSTEMS - SELECTIVE SYNTHESES AND AB-INITIO X-RAY-POWDER DIFFRACTION STRUCTURAL CHARACTERIZATION OF COPPER(I) AND SILVER(I) PYRAZOLATES

Copper(I) and silver(I) pyrazolates, depending on the synthetic method used, appear in two distinct crystalline phases each. The crystal and molecular structures of the polymeric alpha-[Cu(pz)](n) and [Ag(pz)](n) and of the trimeric [Ag(pz)](3) complexes (Hpz = pyrazole) have been determined ab-initio using X-ray powder difrraction data from conventional laboratory equipment and refined with the Rietveld technique. Crystals of alpha-[Cu(pz)](n) are orthorhombic, space group Pbca (no. 61), with a = 6.6684(4) A Angstrom, b = 19.829(1) Angstrom, c = 6.0847(4) Angstrom, and Z = 8; [Ag(pz)](n) crystallizes in the orthorhombic space group Pbca (no. 61) with a = 6.5295(4) Angstrom, b = 20.059(2) Angstrom, c 6.4675(4) Angstrom, and Z = 8. A 1:1 mixed metal phase, [(Cu,Ag)(Pz)](n), has also been prepared which shows high crystallinity with lattice parameters intermediate between those of the pure Cu and Ag phases. [Ag(pz)](3) crystallizes in the orthorhombic space group Pbcn (no. 60) with a = 13.147(1) Angstrom, b = 10.570(1) Angstrom, c = 8.792(1) Angstrom, and Z = 4. For sake of comparison, the crystal structure of the polymeric beta-[Cu(pz)](n) phase has also been refined from X-ray powder diffraction data, using prior knowledge from a single crystal X-ray determination. Crystals of beta-[Cu(pz)](n), are orthorhombic, space group Pbcn (no. 60), with a = 9.933(2) Angstrom, b = 13.348(2) Angstrom, c 5.954(1) Angstrom, and Z = 8. All four polymeric complexes consist of infinite chains of linearly coordinated copper or silver atoms, bridged by bidentate pyrazolato anions, running parallel to the crystallographic c directions. As a result, the alpha-[Cu(pz)](n) and beta-[Cu(pz)](n) phases differ mainly in the interchain Cu...Cu contacts, which are as low as 2.972(6) Angstrom in the beta phase, and in the crystal packing of the polymeric chains. Of the two silver phases, [Ag(pz)](n) is isostructural with alpha-[Cu(pz)](n), while [Ag(pz)](3) is a trimeric complex of idealized D-3h symmetry, topologically similar to that already reported for the 3,5-diphenyl derivative

POWDER ROUTE TO CRYSTAL-STRUCTURES - X-RAY-POWDER DIFFRACTION DETERMINATION OF POLYMERIC SILVER IMIDAZOLATE

Silver imidazolate has been synthesized and its solid-state structure determined, ab initio. from conventional X-ray powder diffraction data only. The crystals are orthorhombic, space group P2(1)2(1)2(1), with a = 5.5759(4), b = 6.7452(4), c = 22.174(1) Angstrom, U = 834.0(1) Angstrom>(3), Z = 8, D-c = 2.786 g cm(-3). The structure was solved by a real-space scavenger technique and refined by the Rietveld method down to R(p) and R(F) values of 0.062 and 0.027, respectively, for 4401 data points (1262 reflections) measured at room temperature in the 17-105 degrees (2 theta) range. The crystal structure of [Ag(im)(n)] (Him = imidazole) consists of a complex packing of polymeric chains folding about the crystallographic c axis, containing linearly co-ordinated silver atoms joined by imidazolate fragments. Short interchain Ag ... Ag contacts [3.161(4) Angstrom] were observed

Dual action Smac mimetics-zinc chelators as pro-apoptotic antitumoral agents

Dual action compounds (DACs) based on 4-substituted aza-bicyclo[5.3.0]decane Smac mimetic scaffolds (ABDs) linked to a Zn(2+)-chelating moiety (DPA, o-hydroxy, m-allyl, N-acyl (E)-phenylhydrazone) through their 10 position are reported and characterized. Their synthesis, their target affinity (XIAP BIR3, Zn(2+)) in cell-free assays, their pro-apoptotic effects and cytotoxicity in tumor cells with varying sensitivity to Smac mimetics are described. The results are interpreted to evaluate the influence of Zn(2+) chelators on cell-free potency and on cellular permeability of DACs, and to propose novel avenues towards more potent antitumoral DACs based on Smac mimetics and Zn(2+) chelation

4-Connected azabicyclo[5.3.0]decane Smac mimetics-Zn2+ chelators as dual action antitumoral agents

Putative dual action compounds (DACs 3a-d) based on azabicyclo[5.3.0]decane (ABD) Smac mimetic scaffolds linked to Zn2+-chelating 2,2'-dipicolylamine (DPA) through their 4 position are reported and characterized. Their synthesis, their target affinity (cIAP1 BIR3, Zn2+) in cell-free assays, their pro-apoptotic effects, and their cytotoxicity in tumor cells with varying sensitivity to Smac mimetics are described. A limited influence of Zn2+ chelation on in vitro activity of DPA-substituted DACs 3a-d was sometimes perceivable, but did not lead to strong cellular synergistic effects. In particular, the linker connecting DPA with the ABD scaffold seems to influence cellular Zn2+-chelation, with longer lipophilic linkers/DAC 3c being the optimal choice

Application of the Ugi reaction with multiple amino acid-derived components: Synthesis and conformational evaluation of piperazine-based minimalist peptidomimetics

The concurrent employment of α-amino acid-derived chiral components such as aldehydes and α-isocyanoacetates, in a sequential Ugi reaction/cyclization two-step strategy, opens the door to the synthesis of three structurally distinct piperazine-based scaffolds, characterized by the presence of l-Ala and/or l-Phe-derived side chains and bearing appropriate functionalities to be easily applied in peptide chemistry. By means of computational studies, these scaffolds have been demonstrated to act as minimalist peptidomimetics, able to mimic a well defined range of peptide secondary structures and therefore potentially useful for the synthesis of small-molecule PPI modulators. Preliminary biological evaluation of two different resistant hepatocellular carcinoma cellular lines, for which differentiation versus resistance ability seem to be strongly correlated with well defined types of PPIs, has revealed a promising antiproliferative activity for selected compounds. © The Royal Society of Chemistry 2015

Improving in vivo plant nitrogen content estimates from digital images: trueness and precision of a new approach as compared to other methods and commercial devices

Operational tools to support nitrogen (N) management in cropping systems are increasingly needed to maximise profit, minimise environmental impact, and to cope with market requirements. In this study, a new method (18%-grey DGCI) for estimating leaf and plant N content from digital photography was evaluated and compared with others based on image processing (DGCI and Corrected DGCI) and with commercial tools (leaf colour chart, SPAD-502, and Dualex 4). All methods were evaluated for rice using data collected in northern Italy in 2013, by adapting the ISO 5725-2 validation protocol. 18%-grey DGCI was further validated on independent data collected in 2014. Dualex achieved the best performances for trueness (R2 = 0.96 and 0.92 for leaf and plant N contents), although it presented partly unsatisfying values for precision (12.33% for repeatability and 14.81% for reproducibility). SPAD, instead, demonstrated the highest precision (repeatability = 4.51%, reproducibility = 4.98%), even if it was ranked third for trueness (R2 = 0.82 and 0.81 for leaf and plant N contents). 18%-grey DGCI was ranked second for trueness (R2 = 0.83 for both leaf and plant N contents) and third for precision (11.11% and 14.47% for repeatability and reproducibility). The good performances of the new method were confirmed during the 2014 experiment (R2 = 0.87 for leaf N content). The 18%-grey DGCI method has been implemented in a smartphone app (PocketN) to provide farmers and technicians with a low-cost diagnostic tool for supporting N management at field level in contexts characterised by low availability of resource