recorded on a Bruker AMX 400 instrument. The UV/vis
spectroscopic studies were performed using a Varian Cary
100 UV-Vis spectrophotometer. Mass spectra were recorded
using a Thermo-Finnigan LCQ Advantage Max electrospray
ionization instrument. For pH-spectrophotometric titrations,
an ORION 420A pH meter equipped with a HANNA Instru-
ments electrode was used. For protonation and complexation
equilibrium constant determination an automated Radiometer
Titralab TIM 900 titration apparatus was used. The synthesis
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of ligand
L starting from 1,3,5-tris(bromomethyl)-2,4,6-
triethylbenzene12a is described in the ESI.w
pH-spectrophotometric titrations
Spectra were recorded in the range 300–800 nm. pH variations
were obtained by the addition of a standard 0.1 M NaOH
solution (mL quantities) to a solution (20 mL, 5 ꢀ 10ꢁ4 M in
water/dioxane 1 : 4, 0.05 M NaNO3 as the ionic medium) of the
fully protonated ligand (obtained by adding a known excess of
acid), with the addition of 3 equivalents of CuII(OTf)2 and
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Spectrophotometric titrations with anions at fixed pH
Spectra were recorded in the range 300–800 nm. To a 5 ꢀ 10ꢁ4 M
solution of L in water/dioxane 1 : 4 and 0.05 M MES were added
3 equivalents of CuII(OTf)2. The pH was then corrected to pH 5.8
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ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008
1842 | New J. Chem., 2008, 32, 1839–1842