Anthracene based surface acoustic wave sensors for picomolar detection of lead ions. Correlation between experimental results and DFT calculations

104 MHz surface acoustic wave (SAW) sensors functionalized with new anthracene derivates were designed for the detection of lead ions (Pb2+) in liquid media. On the basis on quantum chemical calculations, three anthracene molecules have been synthetized and tested: 4-(9-anthrylmethoxy) benzyl[4-(9-anthrylmethoxy)phenyl]sulfone (BPS-AN); 9-{[4-({[4-(9 anthrylmethoxy) phenyl]sulfanyl}methyl)]methyl] anthracene (TDP-AN) and 2,2-bis(4 anthracenylmethoxy-1,1′-biphenyl (BP-AN). Gravimetric results indicate that the affinity of BPS-AN towards Pb2+ ions is superior to that of TDP-AN and BP-AN, confirming thus the computational approach. The designed BPS-AN SAW sensor has a sensitivity of [7.2 ± 4.6]×108 [°/M], a limit of detection (LOD) of 22 pM, and displayed very high affinity to lead ions with an apparent dissociation constant Kd of order of (1.1 ± 2.7) × 10−10. Selectivity was investigated by both gravimetry and DFT calculation. Results indicate that the designed sensor is more sensitive to lead cations than copper and mercury ones. A tetrabutylphosphonium (TBP) lactate ionic liquid (IL) solution was used to regenerate the SAW sensor, permitting its further reuse a dozen times without degrading the BPS-AN recognition layer.