*2.4. Dendrimers Characterization*

The UV-Vis spectrophotometric investigations of the dendrimers were performed on a UV-Vis "Thermo Spectronic Unicam UV 500" double beam spectrophotometer. Fluorescence spectra were taken on a "Cary Eclipse" fluorimeter. The absorption and fluorescence spectra were recorded using 10−<sup>6</sup> mol/L solutions of the dendrimers. The quantum yield of fluorescence was determined by comparing the areas underneath the fluorescence spectra of the dendrimers. Standard quinine bisulfate/H2SO4 1N (Φ<sup>f</sup> = 0.546) was used as standard material to calculate the dendrimer fluorescence quantum yields. ATR FT-IR spectroscopic analyses of dendrimers were performed using an IRAffinity-1 spectrophotometer (Shimadzu Co., Kyoto, Japan) equipped with a MIRacleTM ATR (diamond crystal, depth of penetration of the infrared (IR) beam into the sample was about 2 mm) accessory (PIKE Technologies, Cottonwood, WI, USA). The spectra were recorded from 4000 cm−<sup>1</sup> to 500 cm−<sup>1</sup> with a spectral resolution of 4 cm−<sup>1</sup> using a DLATGS detector equipped with a temperature controller. All spectra were corrected for H2O and CO2 using IR solution internal software. 1H (600.13 MHz) and 13C (150.92 MHz) NMR spectra were acquired on an BRUKER, AVANCE AV600 II+NMR spectrometer (Rheinstetten, Germany). The measurements were carried out in a CDCl3 solution at ambient temperature. The chemical shifts were referenced to a tetramethylsilane (TMS) standard. The EPR spectra of Cu(II) complexes were recorded as the first derivative of the absorption signal by using a Bruker EMXplus EPR spectrometer (Rheinstetten, Germany), operating in the X-band (9.4 GHz). The recording temperature was varied within the range of 120–450 K. The quantitative EPR calculations were performed by SpinCountTM software module (Bruker, Hamburg, Germany). The spectra were simulated using the program SIMFONIA (Bruker, Hamburg, Germany). The effect of the metal cations upon the fluorescence intensity was examined by adding a few L of stock solution of the metal cations to a known volume of the tripod solution (3 mL). The addition was limited to 0.1 mL, so that dilution remained insignificant.
