pH-controlled assembly of two polyoxovanadates based on [V16O38(Cl)]8− and [V15O36(Cl)]6− building blocks
TL;DR: In this article, two new inorganic-organic hybrid polyoxovanadates, [Cu(2,2′-bipy)3]2]2[H4V16O38(Cl)]·4H2O 1 and [CU(2.2′)-Bipy 3]3]3[V15O36(Cl)], were synthesized under the same reaction condition but in different pH range.
About: This article is published in Journal of Molecular Structure.The article was published on 2006-05-08. It has received 18 citations till now.
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TL;DR: Investigation of their structural relations shows the important template role of the polyoxoanions and the synergetic interactions among the polyxoanions, transition-metal ions, and flexible ligand in the assembly process.
Abstract: By introducing the flexible 1,1‘-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the polyoxovanadate system, five novel polyoxoanion-templated architectures based on [As8V14O42]4- and [V16O38Cl]6- building blocks were obtained: [M(bbi)2]2[As8V14O42(H2O)] [M = Co (1), Ni (2), and Zn (3)], [Cu(bbi)]4[As8V14O42(H2O)] (4), and [Cu(bbi)]6[V16O38Cl] (5). Compounds 1−3 are isostructural, and they exhibit a binodal (4,6)-connected 2D structure with Schlafli symbol (34·42)(34·44·54·63)2, in which the polyoxoanion induces a closed four-membered circuit of M4(bbi)4. Compound 4 exhibits an interesting 3D framework constructed from tetradentate [As8V14O42]4- cluster anions and cationic ladderlike double chains. There exists a bigger M8(bbi)6O2 circuit in 4. The 3D extended structure of 5 is composed of heptadentate [V16O38Cl]6- anions and flexural cationic chains; the latter consists of six Cu(bbi) segments arranged alternately. It presents the largest 24-membered circuit of M24(bbi)24 so far observed made of bbi mo...
165 citations
TL;DR: A new discrete cluster, which displays the hitherto unknown 8- charge on the cluster shell and is the first to encapsulate the cyanide anion, has been synthesized and characterized by IR and UV/vis/near-IR spectroscopy, electrochemistry, and magnetic susceptibility measurements.
Abstract: A new discrete [V16O38(CN)]9– cluster, which displays the hitherto unknown 8– charge on the cluster shell and is the first to encapsulate the cyanide anion, has been synthesized and characterized by IR and UV/vis/near-IR spectroscopy, electrochemistry, and magnetic susceptibility measurements. Bond valence sum calculations conducted on the basis of the crystal structure analysis of K9[V16O38(CN)]·13H2O confirm that this new member of the polyoxovanadate series is a mixed-valence complex. The intervalence charge transfer bands arising from intrametal interactions reveal that a localized (class II) assignment is appropriate for the cluster; however, a small degree of electronic delocalization is present. Interesting possibilities exist for the incorporation of this unit into higher dimensionality framework structures, where the redox, optical, and magnetic properties can be exploited and tuned.
55 citations
TL;DR: In this paper, two supramolecular assembly hexadecavanadate derivatives of H2[Cd(phen)3]2{[cd(H2O)(phen)2](V16O38Cl)}·2.5H2
37 citations
TL;DR: Polyanion 1 exhibits blue photoluminescence with an emission maximum at 488 nm, which is characteristic of cerium(III) transitions from 5d to (2)F 5/2 states.
Abstract: A novel pentadecatungstate, [H6Ce2(H2O)Cl(W5O18)3]7− (1), constructed by a dinuclear cerium unit and 15-member ring WO6 units was prepared and characterized by single-crystal X-ray diffraction. Polyanion 1 exhibits blue photoluminescence with an emission maximum at 488 nm, which is characteristic of cerium(III) transitions from 5d to 2F5/2 states. Furthermore, the study of the electrochemical property investigation of 1 shows two reversible redox peaks ascribing to two-electron processes.
29 citations
TL;DR: The direct reaction of B with increasing amounts of DMS in both buffered and non-buffered aqueous solutions revealed the sequential formation of severalVanadium(IV), vanadium(V) and mixed-valence aggregates of different nuclearities, whose relevance to the DNA-protecting activity is discussed.
28 citations
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8,158 citations
TL;DR: In this article, the authors show that crystal engineering is a new organic synthesis, and that rather than being only nominally relevant to organic chemistry, this subject is well within the mainstream, being surprisingly similar to traditional organic synthesis in concept.
Abstract: A crystal of an organic compound is the ultimate supermolecule, and its assembly, governed by chemical and geometrical factors, from individual molecules is the perfect example of solid-state molecular recognition. Implicit in the supramolecular description of a crystal structure is the fact that molecules in a crystal are held together by noncovalent interactions. The need for rational approaches towards solid-state structures of fundamental and practical importance has led to the emergence of crystal engineering, which seeks to understand intermolecular interactions and recognition phenomena in the context of crystal packing. The aim of crystal engineering is to establish reliable connections between molecular and supramolecular structure on the basis of intermolecular interactions. Ideally one would like to identify substructural units in a target supermolecule that can be assembled from logically chosen precursor molecules. Indeed, crystal engineering is a new organic synthesis, and the aim of this article is to show that rather than being only nominally relevant to organic chemistry, this subject is well within the mainstream, being surprisingly similar to traditional organic synthesis in concept. The details vary because one is dealing here with intermolecular interactions rather than with covalent bonds; so this article is divided into two parts. The first is concerned with strategy, highlighting the conceptual relationship between crystal engineering and organic synthesis and introduces the term supramolecular synthon. The second part emphasizes methodology, that is, the chemical and geometrical properties of specific intermolecular interactions.
4,237 citations
TL;DR: Inorganic metal-oxygen cluster anions form a class of compounds that is unique in its topological and electronic versatility and is important in several disciplines, such as analytical and clinical chemistry, catalysis (including photocatalysis), biochemistry, and medicine (antitumoral, antiviral, and even anti-HIV activity) as mentioned in this paper.
Abstract: Inorganic metal–oxygen cluster anions form a class of compounds that is unique in its topological and electronic versatility and is important in several disciplines. Names such as Berzelius, Werner, and Pauling appear in the early literature of the field. These clusters (so-called isopoly- and heteropolyanions) contain highly symmetrical core assemblies of MOx units (M = V, Mo, W) and often adopt quasi-spherical structures based on Archimedean and Platonic solids of considerable topological interest. Understanding the driving force for the formation of high-nuclearity clusters is still a formidable challenge. Polyoxoanions are important models for elucidating the biological and catalytic action of metal–chalcogenide clusters, since metal–metal interactions in the oxo clusters range from very weak (virtually none) to strong (metal–metal bonding) and can be controlled by choice of metal (3d, 4d, 5d), electron population (degree of reduction), and extent of protonation. Mixed-valence vanadates, in particular, show novel capacities for unpaired electrons, and the magnetic properties of these complexes may be tuned in a stepwise manner. Many vanadates also act as cryptands and clathrate hosts not only for neutral molecules and cations but also for anions, whereby a remarkable “induced self-assembly process” often occurs. Polyoxometalates have found applications in analytical and clinical chemistry, catalysis (including photocatalysis), biochemistry (electron transport inhibition), medicine (antitumoral, antiviral, and even anti-HIV activity), and solid-state devices. These fields are the focus of much current research. Metal–oxygen clusters are also present in the geosphere and possibly in the biosphere. The mixed–valence vanadates contribute to an understanding of the extremely versatile geochemistry of the metal. The significant differences between the chemistry of the polyoxoanions and that of the thioanions of the same elements is of relevance to heterogeneous catalysis, bioinorganic chemistry, and veterinary medicine.
3,202 citations
TL;DR: A blueprint for the design of oxide materials is provided by nature and members of the ever-expanding class of polymeric coordination complex cations, novel molybdenum oxide substructures, such as the one shown, may be prepared.
Abstract: A blueprint for the design of oxide materials is provided by nature. By borrowing from nature's ability to influence inorganic microstructures in biomineralization processes and in the hydrothermal synthesis of complex minerals, a new class of materials in which organic components exert a role in controlling inorganic microstructure is evolving. By employing members of the ever-expanding class of polymeric coordination complex cations, novel molybdenum oxide substructures, such as the one shown, may be prepared.
2,371 citations
1,689 citations