4th EucheMs chemistry congress

Poster Session 1
s953
chem. Listy 106, s587–s1425 (2012)
Poster session 1 - inorganic Chemistry
P - 0 1 8 4
CirCuLAr heLiCAteS And A MoLeCuLAr
PentAfoiL Knot
J. e. BeveS 1 , J. f. AyMe 2 , d. A. LeiGh 2 ,
r. t. MCBurney 2 , K. riSSAnen 3
1 Nanjing University, Key State Laboratory for Coordination
Chemistry School of Chemistry, Nanjing, China
2 University of Edinburgh, School of Chemistry, Edinburgh,
United Kingdom
3 University of Jyväskylä, Department of Chemistry, Jyväskylä,
Finland
Knots are being discovered with increasing frequency in
both biological and synthetic macromolecules and have been
fundamental topological targets for chemical synthesis for the past
two decades. Here we present the synthesis of the most complex
non-DNA molecular knot prepared to date: [1, 2] the self-assembly
of five bis-aldehyde and five bis-amine building blocks about five
metal cations and one chloride anion to form a 160-atom-loop
molecular pentafoil knot (five crossing points). The structure and
topology of the knot is established by NMR spectroscopy, mass
spectrometry and X-ray crystallography, revealing a symmetrical
closed-loop double helicate with the chloride anion held at the
centre of the pentafoil knot by ten CH...Cl– hydrogen bonds. The
one-pot self-assembly reaction features an exceptional number of
different design elements.
The synthesis of eleven pentameric related cyclic helicates
is also reported. The factors influencing the assembly process
(reactant stoichiometry, concentration, solvent, nature and amount
of anion) were studied in detail: the role of chloride in the
assembly process appears not to be limited to that of a simple
template and larger circular helicates observed with related
tris(bipyridine) ligands with different iron salts are not produced
with the imine ligands. Using certain chiral amines, pentameric
cyclic helices of single handedness could be isolated and the
stereochemistry of the helix determined by circular dichroism.
We anticipate that the strategies and tactics used here can be
applied to the rational synthesis of other higher-order interlocked
molecular architectures.
references:
1. J. -F. Ayme, J. E. Beves, D. A. Leigh, R. T. McBurney,
K. Rissanen, D. Schultz, Nature Chem., 2012, 4, 15-20.
2. J. -F. Ayme, J. E. Beves, D. A. Leigh, R. T. McBurney,
K. Rissanen, D. Schultz, J. Am. Chem. Soc, 2012,
accepted.
Keywords: Supramolecular chemistry; Circular dichroism;
Bridging ligands; Self-assembly; Anions;
4 th EucheMs chemistry congress
P - 0 1 8 5
Low teMPerAture SyntheSiS of
GeL-nAnoStruCtured SiLver vAnAdiuM
oxideS CAthode MAteriALS
r. fernández de LuiS 1 , M. i. ArriortuA 1
1 Universidad del País Vasco., Mineralogy and Petrology,
Leioa-Bizkaia, Spain
Silver vanadium oxides (SVO) have potential applications
in rechargeable high-energy density lithium batteries and
photo-catalysis due to their excellent electrochemical and
photophysical properties. Recently, several researching groups
have obtained different nanostructured SVO via hydrothermal
treatments.
The main aim of this work is to determine the effect of initial
synthesis conditions on the particle size and morphology of
α-AgVO and β-AgVO SVO. The solution and hydrothermal
3 3
AgNO /NaVO /H O systems were studied, considering the
3 3 2
economic cost versus the health hazards and environmental risks
of the initial reagents with respect to V O , NH VO or Ag O.
2 5 4 3 2
The particle size and morphology were checked by particle size
analyzer, X-ray diffraction and electron microscopy.
With regard to the α-AgVO and β-AgVO compounds
3 3
obtained at room temperature, the α-AgVO compound
3
transformation to β-AgVO depends on the stirring time. The
3
electron microscopy images indicate that in a first step tabular
micro-sized crystals agglomerated in spherical particles
crystallize, and in the second step nano-tubular morphologies
of 300-400nm x10nm x 10nm grow. If ethanol is used as
co-dissolvent, the tabular like single crystals are completely
recovered by 300-30x200-20x10 nm nano-tabular crystals. The
α-AgVO to β-AgVO transformation does not seem to affect the
3 3
particle morphology. For the hydrothermal treatments at 120 and
180ºC, the β-AgVO obtained at neutral pH conditions crystallize
3
as orange powders; however those ones synthesized at slightly
acidic pHs, and with a starting vanadium rich stoichiometry
crystallize as orange-red gels. The electron microscopy images
indicate that nano-tubular (100-200x0.5x0.5 nm) samples of
β-AgVO are obtained after one hour of hydrothermal treatment
3
at 120ºC.
Acknowledgments: This work was financially supported by the
“Ministerio de Ciencia e Innovación” (MAT2010-15375) and
the Bask Country Government (IT-177-07), which we gratefully
acknowledge. R. Fernández thanks to “Ministerio de Ciencia e
Innovación” for funding. The authors thanks to the technicians
of SGIKer (UPV/EHU) for the support.
Keywords: Silver Vanadium Oxide; Hydrothermal synthesis;
Nanotubes; Li-Ion Batteries;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc