Building block libraries and structural considerations in the self-assembly of polyoxometalate and polyoxothiometalate systems

Inorganic metal-oxide clusters form a class of compounds that are unique in their topological and electronic versatility and are becoming increasingly more important in a variety of applications. Namely, Polyoxometalates (POMs) have shown an unmatched range of physical properties and the ability to form structures that can bridge several length scales. The formation of these molecular clusters is often ambiguous and is governed by self-assembly processes that limit our ability to rationally design such molecules. However, recent years have shown that by considering new building block principles the design and discovery of novel complex clusters is aiding our understanding of this process. Now with current progress in thiometalate chemistry, specifically polyoxothiometalates (POTM), the field of inorganic molecular clusters has further diversified allowing for the targeted development of molecules with specific functionality. This chapter discusses the main differences between POM and POTM systems and how this affects synthetic methodologies and reactivities. We will illustrate how careful structural considerations can lead to the generation of novel building blocks and further deepen our understanding of complex systems

Gendered patterning of relationships: Insights from reproductive health networks in Bangladesh

Purpose: Social capital has become a general tool for policy interventions in developing countries – often put forward as empowering and improving women’s socioeconomic position. Using the framework of gendered manifestations of networks in patriarchal setting of Bangladesh, the authors argue that while networks are crucial building blocks of social capital they are bound to manifest differently depending on the context in which they are embedded. The paper aims to discuss this issue. Design/methodology/approach: By combining methods of social networks and spatial analysis, this study provides insights into the embeddedness of networks in gender norms. The authors conduct the study in the context of reproductive health networks in rural Bangladesh. Findings: The findings suggest that networks mirror the structure of the society in which they evolve, reproducing rather than challenging disadvantage. Research limitations/implications: The authors call for a more nuanced view of social capital leading to policy design that is sensitive to different manifestations of networks. Originality/value: This study is the first to combine novel methods of social networks and spatial analysis to quantify the complex interplay between social networks and gender norms. This study further contributes to the diffusion literature by providing the first comparative view of women’s and men’s reproductive health networks that extend beyond actors’ direct tie

The nature of fair trade exchanges and their outcomes: Producer voices in Vietnam and India

This paper brings insights to Fair Trade exchanges by casting commodities beyond material and pecuniary gains to include interpersonal relations. Although numerous studies have highlighted that Fair Trade brings benefits beyond the economic, the process through which ‘material things’ may become imbued with non-pecuniary value remains under-explored. Our analysis of interviews with Fairtrade certified smallholder farmers in Vietnam and in India provides insight into the discursive constructs of their participation in Fair Trade exchanges. Social exchange theory enables us to reconceptualise exchanges in the Fairtrade market to take into account interpersonal processes and long-term relations of exchange between actors. We find that Fair Trade is associated with benefits to both community and individuals and that these are intertwined and linked to participation in a democratic process in the cooperative. The pecuniary and non-pecuniary value generated and sustained by farmer democratic organizations needs to be recognised by Fairtrade importing businesses

Mesolabii expositio Bern. Salignaco authore.

GLN-2521CDM, p. 82Drummond, Aberdeen, n° 3573Linet-Hillard, Ste-Geneviève, n° 181

Mechanistic changeover for the water substitution on fac-[(CO)(3)Re(H(2)O)(3)](+) revealed by high-pressure NMR

Copyright © 2004 American Chemical SocietyPascal V. Grundler, Bernadette Salignac, Sonia Cayemittes, Roger Alberto, and André E. Merbac

Mechanistic changeover for the water substitution on fac-[(CO)3Re(H2O)3]+ revealed by high-pressure NMR.

The complex formation in water between the stable tricarbonyltriaqua fac-[(CO)(3)Re(H(2)O)(3)](+) (1) complex and N- and S-donor ligands has been studied by high-pressure (1)H NMR. Rate and equilibrium constants for the formation of [(CO)(3)Re(Pyz)(H(2)O)(2)](+), [(CO)(3)(H(2)O)(2)Re(mu-Pyz)Re(H(2)O)(2)(CO)(3)](2+), [(CO)(3)Re(THT)(H(2)O)(2)](+), and [(CO)(3)Re(DMS)(n)()(H(2)O)(3-n)](+) (n = 1-3) (Pyz = pyrazine, THT = tetrahydrothiophene, DMS = dimethyl sulfide) have been determined and are in accord with previous results (Salignac, B.; Grundler, P. V.; Cayemittes, S.; Frey, U.; Scopelliti, R.; Merbach, A. E.; Hedinger, R.; Hegetschweiler, K.; Alberto, R.; Prinz, U.; Raabe, G.; Kölle, U.; Hall, S. Inorg. Chem. 2003, 42, 3516). The calculated interchange rate constant k(1)' (Eigen-Wilkins mechanism) increases from the hard O- and N-donors to the soft S-donors, as exemplified by the following series: TFA (trifluoroacetate) (k(1)' = 2.9 x 10(-3) s(-1)) < Br(-) < CH(3)CN < Pyz < THT < DMS < TU (thiourea) (k(1)' = 41.5 x 10(-3) s(-1)). On the other hand, values remain close to that of water exchange k(ex) on 1 (k(ex) = 6.3 x 10(-3) s(-1)). Thus, an I(d) mechanism was assigned, suggesting however the possibility of a slight deviation toward an associatively activated mechanism with the S-donor ligands. Activation volumes determined by high-pressure NMR, for Pyz as Delta V(++)(f,1) = +5.4 +/- 1.5, Delta V(++)(r,1) = +7.9 +/- 1.2 cm(3) mol(-)(1), for THT as Delta V(++)(f,1) = -6.6 +/- 1, Delta V(++)(r,1) = -6.2 +/- 1 cm(3) mol(-1), and for DMS as Delta V(++)(f,1) = -12 +/- 1, Delta V(++)(r,1) = -10 +/- 2 cm(3) mol(-1) revealed the ambivalent character of 1 toward water substitution. Hence, these findings are interpreted as a gradual changeover of the reaction mechanism from a dissociatively activated one (I(d)), with the hard O- and N-donor ligands, to an associatively activated one (I(a)), with the soft S-donor ligands

Les aventures de Télémaque /

"Notes sur quelques éditions de Télémaque": v. 1, p. ciii-cxxv.At head of title: Fénelon.Mode of access: Internet

Reactivity of the organometallic fac-[(CO)(3)Re(1)(H(2)O)(3)](+) aquaion. Kinetic and thermodynamic properties of H(2)O substitution

Copyright © 2003 American Chemical SocietyBernadette Salignac, Pascal V. Grundler, Sonia Cayemittes, Urban Frey, Rosario Scopelliti, André E. Merbach, Roman Hedinger, Kaspar Hegetschweiler, Roger Alberto, Ulrich Prinz, Gerhard Raabe, Ulrich Kölle, and Syd Hal