All commercially available reagents were used as received from
suppliers. Solvents (Sigma-Aldrich) were dried when required using
an appropriate drying agent. Reactions requiring anhydrous conditions
were carried out using Schlenk-line techniques under an atmosphere
of dry argon. Water refers to high purity H2O obtained
from the “Millipore Elix 10” purification system. Eu(CF3SO3)3 (Aldrich, 98%) was stored under
vacuum for several days at 80 °C and then transferred to the
glovebox. All other chemicals were purchased from Alfa Aesar. Thin-layer
chromatography was carried out on neutral alumina plates (Fluka Analytical)
or silica plates (Sigma-Aldrich) and visualized under UV lamp (254
nm). The cationic exchange chromatography was performed on SCX cartridges
(1 g) purchased from “Agilent Technologies-Sample Prep solutions”.
4-Morpholinepropanesulfonic acid (MOPS) buffer (purity 99%) was dissolved
in 0.9% w/v NaCl water solution. The pH value was corrected to the
physiological value (7.4) by dropwise addition of freshly prepared
NaOH 10 M. Stock solution of BSA (purity ≥99%, purchased from
Sigma-Aldrich) was freshly prepared and used (2 × 10–4 mol L–1) by dissolving the protein in MOPS buffer.
The solution was kept in the dark at 4 °C before use.
suppliers. Solvents (Sigma-Aldrich) were dried when required using
an appropriate drying agent. Reactions requiring anhydrous conditions
were carried out using Schlenk-line techniques under an atmosphere
of dry argon. Water refers to high purity H2O obtained
from the “Millipore Elix 10” purification system. Eu(CF3SO3)3 (Aldrich, 98%) was stored under
vacuum for several days at 80 °C and then transferred to the
glovebox. All other chemicals were purchased from Alfa Aesar. Thin-layer
chromatography was carried out on neutral alumina plates (Fluka Analytical)
or silica plates (Sigma-Aldrich) and visualized under UV lamp (254
nm). The cationic exchange chromatography was performed on SCX cartridges
(1 g) purchased from “Agilent Technologies-Sample Prep solutions”.
4-Morpholinepropanesulfonic acid (MOPS) buffer (purity 99%) was dissolved
in 0.9% w/v NaCl water solution. The pH value was corrected to the
physiological value (7.4) by dropwise addition of freshly prepared
NaOH 10 M. Stock solution of BSA (purity ≥99%, purchased from
Sigma-Aldrich) was freshly prepared and used (2 × 10–4 mol L–1) by dissolving the protein in MOPS buffer.
The solution was kept in the dark at 4 °C before use.