360 research outputs found
Homoleptic metal complexes of 4'-(5-pyrimidinyl)-2,2':6',2''-terpyridine : tetrafurcated expanded ligands
No full textWith iron(II) and ruthenium(II), 4`-(5-pyrimidinyl)-2,2`: 6`,2 ``-terpyridine (L) preferentially coordinates through the tpy domain to give octahedral [ML2](2+) (M Fe, Ru) complexes. Treatment of [RuL2][PF6](2) with CuCl2 center dot 2H(2)O leads to [Ru(2)(2)][CuCl2(OH2)][CuCl3]Cl center dot 3MeCN center dot 7H(2)O(n) which exhibits a two-dimensional coordination network with copper(II) centres interconnecting [RuL2](2+) motifs. Magnetic susceptibility data for the material are consistent with a one-dimensional S = 1/2 antiferromagnetic chain
Structural diversity in the reactions of 4 '-(pyridyl)-2,2 ':6 ',2 ''-terpyridine ligands and bis{4 '-(4-pyridyl)-2,2 ':6 ',2 ''-terpyridine}iron(II) with copper(II) salts
No full textWe have demonstrated that treatment of [Fe(1)(2)](2+) (1 = 4'-(4-pyridyl)-2,2':6',2 ''-terpyridine) with an excess of CuCl2 center dot 2H(2)O leads to competition between coordination of copper(II) by the pendant pyridine donors in [Fe(1)(2)](2+), and transfer of ligand 1 from iron(II) to copper(II) to yield [{Cl3Cu(mu-1)Fe(mu-1)}(2)CuCl2(OH2)(2)]Cl-2 center dot 4H(2)O and [Cu(H1)Cl-2]Cl center dot 4H(2)O, respectively. Direct reaction of 1 with CuCl2 center dot 2H(2)O and variation in crystallization conditions results in the formation of either monomeric or polymeric complexes: [Cu(1)Cl-2]center dot 4.75H(2)O, [Cu(1)Cl-2]center dot H2O center dot MeOH and [Cu(1)Cl-2 center dot 2H(2)O](n). The reaction of 1 with Cu(NO3)(2)center dot 3H(2)O gives the coordination polymer [Cu(1)(ONO2)(2)center dot H2O](n). Magnetic data for [Cu(1)Cl-2 center dot 2H(2)O](n) and [Cu(1)(ONO2)(2)center dot H2O](n) are consistent with antiferromagnetically- coupled chains. Reactions of CuCl2 center dot 2H(2)O with ligands 2 and 3 (2 = 4'-(3-pyridyl)-2,2':6',2 ''-terpyridine, 3 = 4'-(2-pyridyl)-2,2':6',2 ''-terpyridine) lead to monomeric complexes. With the exception of [Cu(3)Cl-2], the mononuclear complexes show a propensity for the incorporation of water into their crystal lattices; in the case of [Cu(H1)Cl-2]Cl center dot 4H(2)O and [Cu(H1)Cl-2]Cl center dot 4.75H(2)O, the small change in water content leads to the assembly of (5.8(2))(2)(5.6.8)(4)(5(2).6)(2) or (4(2).6(2))(3)(4.6(2))(6) water-chloride ion nets
The global food chain
No full textJonathon Porritt is Founder Director of Forum for the Future www.forumforthefuture.org.uk; Chairman of the UK Sustainable Development Commission www.sd-commission.org.uk; and author of Capitalism as if the World Matters (Earthscan, 2007)
Reversibly Tuning the Viscosity of Peptide-Based Solutions Using Visible Light
No full textLight can be used to design stimuli–responsive systems. We induce transient changes in the assembly of a low molecular weight gelator solution using a merocyanine photoacid. Through our approach, reversible viscosity changes can be achieved via irradiation, delivering systems where flow can be controlled non-invasively on demand.</p
A Bridge Too Far: Testing the Limits of Polypyridyl Ligands in Bridging Soluble Subunits of a Coordination Polymer
No full textStarting with a coordination polymer, {[Cu(L)]2}n (1 where H2L = salicylidene-2-aminophenol), we have explored the ability of polypyridyl ligands (P) to bridge the monomer complex to form nine {[Cu(L)]2(P)} complexes. The identity and solution stability of the [Cu(L)] units has been investigated through a novel combined UV–vis/EPR experiment and it has been found to be a stable supramolecular building unit for the construction of discrete complexes and coordination polymers. The reorganization of [Cu(L)] units to a new coordination polymer on addition of 4,4′-bipyridine markedly changes the connectivity of the structure and the magnitude of the antiferromagnetic interactions through reorientation of the Cu(II) orbitals. We also present the structure of 1, 80 years after its synthesis was first reported
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Destination-Based Brand Equity: The Impact of Destination Image on the destination stakeholders
No full textDr Jonathon Day
Dr Jonathon Day is an Associate Professor in Purdue’s School of Hospitality and Tourism Management. In addition to over 45 academic articles and chapters, he is the author of “Introduction to Sustainable Tourism and Responsible Travel” and co-author of “The Tourism System 8th Edition” . Dr Day’s research interests focus on sustainable tourism and responsible travel.
Gurpreet Kour
Gurpreet is an assistant professor at the Indian Institute of Management, Shillong. Her research interests include destination barnding and destination governance. Destination image has been an important topic in tourism research. The appeal of a destination’s image can contribute to a destination’s competitiveness. A wide range of factors contribute to the strength of the destination image, and the value extends beyond consumers to destination stakeholders. While a range of issues around destination image have been examined, there remains much to be explored. There is a paucity of research on the value created for these stakeholders by the brand image. There is also a gap in our understanding of the impact of destination image on destination stakeholder behavior. It is anticipated that operators in destinations with an image that emphasizes nature, and the environment will be more likely to undertake environmentally sustainable activities. This study aims to understand how the stakeholder perceives the value of the destination image and the impact of image considerations on stakeholders' actions in a destination
A conceptual review of interprofessional expertise in child safeguarding
No full textIt is increasingly accepted that practitioners across a range of professional fields must work together in order to promote children's welfare and protect them from harm. However, it has also become apparent that interprofessional working is a challenging area of practice that cannot simply be prescribed through protocols and procedures, nor acquired as a set of technical competences. This article develops the concept of interprofessional expertise in order to explain how practitioners become more proficient at working with others to manage complex child welfare issues. Key principles are outlined with reference to relevant theoretical frameworks, including models of skill acquisition. The article concludes by discussing some potential implications for future research and contemporary developments in child safeguarding practice
New discrete metallocycles incorporating palladium(II) and platinum(II) corners and dipyridyldibenzotetraaza[14]annulene side units
No full textMetal Template Synthesis of Molecular Knots and Links
No full textThe use of metal ions as templates to direct the assembly of complex architectures and topologies is briefly reviewed, highlighting milestones in the field from [2]catenanes, through to trefoil knots, Solomon links, Borromean rings and most recently to a molecular pentafoil knot
Crystal engineering with 2,2':6',2"- terpyridine derivatives and their metal complexes : from simple building blocks to coordination polymers and networks
No full textThis thesis concerns the design of ligands for use in the construction of larger
supramolecular systems, with emphasis on the application of 4'-substitured 2,2',6',2''-
terpyridine ligands and their iron(II) and ruthenium(II) complexes in crystal engineering.
The first section considers 4'-hydrazone functionalized 2,2',6',2''-terpyridines and their
dynamic behaviour in solution and structural characteristics in the solid state, with respect
to protonation. Neutral, mono- and di-protonated ligands are considered. The iron(II) and
ruthenium(II) complexes of these ligands are reported and their properties studied by
variable temperature NMR, UV-visible spectroscopy and single crystal X-ray
crystallography. Subtle changes in substituents were found to have dramatic effects on
crystal packing and some common packing arrangements were identified. A range of
potential ‘expanded ligands’ (complexes which can themselves act as ligands for additional
metal centres), are introduced in the next section. These can be potentially used to bridge
metal centres to form both discrete and infinite structures, in particular in the solid state. In
a systematic study of single crystal X-ray crystal structures of these complexes many were
found to be more flexible than they first appear, and that the crystal packing arrangements
were often sensitive to solvent. The next section describes the first crystallographically
characterized coordination polymers and networks which include metal bis(terpyridine)
units. Self-complementary hydrogen bonding was also found to be a stabilizing motif, with
a number of such structures prepared. The final chapter blends the ideas of previous
sections: 4'-(x-pyridyl) functionalized 2,2',6',2''-terpyridine ligands are used to form
‘expanded ligands’ with iron(II) and ruthenium(II) centres. These were characterized in
solution, with protonation of the distant pendant pyridyl ring found to significantly
influence the MLCT absorption of the complexes. These complexes were incorporated into
two larger structures and characterised by single crystal X-ray crystallography. A selfcomplementary
hydrogen bonded polymer which possesses nanopores through the crystal
lattice is reported. Iron bis(thiocyanate) was also used to form a bridged coordination
polymer
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