196,890 research outputs found
Shakespeare's metaphorical swarms in The Two Gentlemen of Verona: textual and pragmatic features and their impact on the Italian translation
No full textThis chapter focuses on the theoretical concept of “metaphorical swarm” and its implications for translation. The analysis of some excerpts from Shakespeare’s text and their translation into Italian offers a starting point for Rizzato to stress that metaphorical occurrences in literary texts cannot and must not be considered in isolation from each other but must rather be read as part of the network of conceptual metaphors that integrates the entire work. Only in this way will it be possible to translate the metaphorical swarms that underlie Shakespeare’s text and make it unique
Crystal growth of coordination polymers by gel diffusion
No full textThe use of gels or viscous materials as growth media for a wide range of compounds, including proteins, inorganic and organic compounds has already been reported in the literature. In the presence of a gel, sedimentation and convection currents are greatly suppressed and the mass transport of the molecules occurs mainly by diffusion. As a result, a lower nucleation density and a better crystal quality are usually observed.[1a] We report, here, new interesting phenomena observed in crystallization experiments ofcoordination compounds by using gels as diffusion media.[1b].
We have tested a variety of gel and resin-like systems as dispersion matrixes to crystallize a special class of polymeric and porous inorganic compound: the “coordination polymers”. We have used the gel technique to increase the size and quality of the crystals and as a mean to modify the crystal habit and get new crystalline species. [1b] In our experiments, we have observed some new phenomena of gel inclusion and morphological alteration of crystal surfaces.
Diffraction, optical observations and interferometric measurements have been used for in situ monitoring the mass transport in the gelled/fluid phase during the crystallization process and for studying the crystallization kinetic.
Funding from the Cariplo Foundation grant ‘‘2012‐0921” is gratefully acknowledged.
[1] a) K.H. Henisch, Crystals in Gels and Liesegang Rings, Cambridge University Press, Cambridge, 1998; b) L.
Carlucci, G. Ciani, J. M. Garcìa-Ruiz, M. Moret, D. M. Proserpio and S. Rizzato Cryst. Growth Des., 2009, 9(12),
5024-5034.
[2] S.Rizzato et al., unpublished results
Esordio polmonare ed extrapplmonare della sarcoidosi: Confronto tra una casistica prospettica e quella del registro RIPID
No full textBackground and aim: RIPID (Registro Italiano Pneumopatie Interstiziali Diffuse) is a register started May 98 to pull together a number of data (age, gender, race, diagnosis, diagnostic criteria, symptoms at presentation and other data) of patients with interstitial lung diseases. Aim of this work is to compare the data of two italian series of sarcoid patients, one recently published from an Internal Medicine Division (Rizzato et al 2004), the other one from the RIPID Pneumological Centers. Results: The major differences regard the percentage of extrapulmonary presentation (Rizzato 36%, RIPID 8%), the percentage of Lofgren syndrome (Rizzato 21%, RIPID 10%), the presentation with respiratory symptoms (Rizzato 13%, RIPID 60%), the prentation with Chest X ray by chance (Rizzato 25%, RIPID 14%), the percentage of histologically proven cases (Rizzato 80%, RIPID 60%), the pulmonary (versus non pulmonary) histological approach to diagnosis (Rizzato 42%, RIPID 91%). Most of the above differences may be explained on the basis of 3 factors: a) the Rizzato report has been perspective, while the RIPID is simply a register; b) the case mix of patients visiting the Pneumological Centres is more lung-oriented in respect to patients visiting an Internal Medicine Division; c) probably the pneumologists are more likely to use transbronchial biopsy, while the internists are more likely to use extra-pulmonary biopsies. Conclusion: In the Pneumological Centres the clinical approach to the patient is different in respect to what happens in an Internal Medicine Division, perhaps due to a different case mix of the patients
Morphological and structural effects of gels on coordination polymers crystallization
No full textThe use of gels or viscous materials as growth media for a wide range of compounds, including proteins and inorganic and organic compounds has been reported in the literature. In the presence of gel, sedimentation and convection currents are greatly suppressed and the mass transport of the molecules mainly occurs by diffusion, resulting, usually, in a lower nucleation density and a better crystal quality.[1a]
Here we report some new interesting phenomena observed in crystallization experiments of coordination compounds, such as, “coordination polymers”, by using gels as diffusion media.[1b]
By using a semi-liquid silica-gel system as a dispersion matrix, we were able to increase the quality of the crystals but also slow down the solvent loss, stabilizing the partially dehydrated structure of a very flexible porous framework. This has enabled an accurate determination of the dynamic behavior of the system during the desolvation process by using single crystal X-ray diffraction. Unit cells and structure solution has been obtained at any point during the process.
The improved stability of the crystals and the large flexibility of the network have also made possible to carry out in-situ high-pressure diffraction measurements.
Other important results concern the effects of gels on the macroscopic crystal shape and on the micromorphology of the crystal surfaces (Figure), and the capacity of gel media to promote the concomitant crystallization of topological isomers with a monotropic relationship.[2]
Funding from the Cariplo Foundation under the grant ‘‘2012‐0921” is gratefully acknowledged.
[1] a) K.H. Henisch, Crystals in Gels and Liesegang Rings, Cambridge University Press, Cambridge, 1998; b) L. Carlucci, G. Ciani, J. M. Garcìa-Ruiz, M. Moret, D. M. Proserpio and S. Rizzato Cryst. Growth Des., 2009, 9(12), 5024-5034.
[2] S.Rizzato et al., unpublished results
Porosity and crystal morphology of heterometallic coordination networks from β-diketonate ligands
No full textPorous coordination polymers (PCPs) or metal-organic-frameworks (MOFs) are considered very promising porous materials that can be exploited in many different technological fields such as gas storage, heterogeneous catalysis and separation of mixtures. In the field of MOF materials, many efforts are devoted to the search of rational synthetic procedures. Among others, a useful synthetic strategy is the so-called Metalloligand (MLs) approach. MLs are coordination complexes containing suitably oriented exo donor-groups that, used in place of organic linkers, can orient the formation of desired homo and heterometallic polymeric architectures [1]. Functionalized chelating ligands suited to obtain useful MLs are -diketonate molecules.[2]
We report the synthesis and the structural characterization of two families of coordination frameworks obtained through the use of different -diketonate ligands with copper salts of several counter-ions. The first family of polymers have a two-dimensional layered structure whereas the members of the second family adopt a three-dimensional flexible framework structure.
We have focused our attention to the correlations between the crystal structure, the dimensionality, the topology and porosity of the networks and the crystal morphologies, as well as to the investigation of the surface phenomena during the crystal growing process. Moreover, we have mapped a continuous set of crystal morphologies by controlling experimental variables such as the solvent system, the metal-ligand molar ratio and the nature of the counter-anion. The aim is to develop a method to tune the crystal habit according to the specific requirement of some important applications.[3]
[1] S. Kitagawa, R. Kitaura, S. Noro Angew. Chem., Int. Ed., 43 (2004) 2334.
[2] L. Carlucci, G. Ciani, S. Maggini, D.M. Proserpio, M. Visconti, Chem. Eur. J, 16 (2010) 12328.
[3] L. Carlucci, G. Ciani, J. M. Garcìa-Ruiz, M. Moret, D. M. Proserpio and S. Rizzato , Cryst. Growth Des., 2009, 9(12), 5024-5034
Neutrons in chemistry : contributions of single crystal neutron diffraction to coordination chemistry
No full text1. Introduction
Single crystal neutron diffraction is the technique of choice for unambiguously and accurately locating hydrogen atoms even in the presence of nearby “heavy atoms”. Recent advances in instrumentation and neutron sources are opening up new possibilities: in particular the use of fairly small crystals and short data collection times.
2. Results and Discussion
We will report three examples to illustrate the power of this technique in inorganic chemistry:
1) the first unambiguous structural evidence for non-conventional hydrogen bonding between a water molecule and a metal center in trans-[PtCl2(NH3)(N-glycine)]∙H2O.[1]
2) The coordination geometries of the binary platinum hydrides [Pt2(P-P)2(H)3]+ (P-P = dppb: 1,4–Bis(diphenylphosphino)butane and dpe: 1,2–Bis(diphenylphosphino)ethane).
3) The unambiguous location of deuterium atoms in the deuterated form of RuH2(η2-H2)2(PCyp3)2 (Cyp = cyclopentyl) complex as a proof of the metal-mediated C-H activation.[2]
3. References
[1] Silvia Rizzato, Jacqueline Bergès, Sax A. Mason, Alberto Albinati and Jiří Kozelka, Angew. Chem. Int. Ed., in press.
[2] M. Grellier, L. Vendier, B. Chaudret, A. Albinati, S. Rizzato, S. A. Mason and S. Sabo-Etienne J. Am. Chem. Soc., 2005,127 (50), 17593
A crystallographic route to understand drug solubility: the case of 4- aminoquinoline antimalarials
No full textMost Active Pharmaceutical Ingredients (API) can be prepared in various crystalline forms [1] displaying largely different physical/chemical properties and bioavailability. Salt formation represents the most common and simplest chemical way to modify the overall features but also the toxicity and biopharmaceutical availability of a drug substance. However, it is often unclear how and why the chemical and crystallographic characters can cooperate in determining these changes. We here face the problem from the perspective of the antiplasmodial drug piperaquine (PQ, C29H32Cl2N6) [2]. Being highly lipophilic, both neutral PQ and its commercial hydrogen phosphate tetrahydrate salt are poorly soluble in water, resulting in a reduced oral bioavailability. We synthesized five novel PQ salts and characterized them by both single crystal X–ray diffraction methods and T-dependent (20 – 50 oC) UV–Vis spectroscopy. Our aim was to explore possible relationships among non-covalent interaction networks in the crystals and measured solubilities. We also estimated changes in thermodynamic state functions related to the solvation process by DFT simulations, both in vacuo and in the solid state. We found that solubilities of PQ salts conform in most cases to the Hard and Soft Acid and Bases (HSAB) rules, i.e. less soluble compounds bear ions of comparable hardness. Crystal packing plays a far less important role, even though disorder-related entropic effects can influence the response of solubility to temperature. A possible take-home message is that intensive thermodynamic properties stem from a non-trivial cooperation several physicochemical effects. A first-principle understanding of the drug solubility cannot rely just on the description of the crystal packing, but must take into account the explicit evaluation of interaction energetics and pertinent electronic factors. [1] R. Hilfiker and M. von Raumer, Polymorphism in the Pharmaceutical Industry: Solid Form and Drug Development. 2019, Wiley-VCH, Weinheim (Germany). ISBN: 978-3-527-34040-8. [2] P. Sacchi, L. Loconte, G. Macetti, S. Rizzato and L. Lo Presti Crystal Growth Des. 2019. 19, 139
“Presentazione” a Quaderni del CIRM Centro Interuniversitario di Ricerca sulle Metafore: Numero 1
No full textCrystallization Behavior of Coordination Polymers. 2. Surface Micro-Morphology and Growth Mechanisms of [Cu(bpp)3Cl2] 3 2H2O by in Situ Atomic Force Microscopy
No full textCrystal growth of the one-dimensional coordination polymer [Cu(1,3-bis(4-pyridyl)propane)3Cl2]·2H2O was investigated in aqueous solutions by in situ atomic force microscopy. Details about the growth mechanisms of the {001} form at low supersaturation were obtained. In particular, growth hillocks due to simple and complex dislocation sources were observed as the only active mechanism. The thinnest steps observed on {001} faces and delimiting growth hillocks were d002 layers, in accordance with the elementary growth layer expected from the systematic extinction conditions of space group I2/a and hence from Bravais−Friedel−Donnay−Harker rules and Hartman and Perdok periodic bond chains theory. This feature of the {001} faces suggests that small oligomeric species can be involved in the crystal growth processes. The effects of unknown impurities in the organic ligand upon the growth of crystals of the title compound were also studied
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