A new perspective on the beryllium sensor platform: Low symmetry phthalocyanine-based molecular design and ultra trace amount Be2+ ion recognition in aqueous media

Abstract New multichannel sensors based on unsymmetrical phthalocyanines (P—A3BZnPc (1) and its water-soluble form Q—A3BZnPc (2)) were developed for Be2+ determination in water and THF. The structures of the sensors were elucidated by single-crystal X-ray diffraction and spectroscopic methods such as 1H- and 13C-NMR, IR, MALDI-TOF-MS, UV–vis, and steady-state fluorescence. The sensors (1) and (2) are dual-channel sensors and operate in the NIR region with  λabs-λemm wavelengths of 685 nm –702 nm and 690 nm–706 nm, respectively. The selectivity of the sensors against Be2+ was explored in the presence of different metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Al3+, Hg2+, Ni2+, Cd2+, Zn2+, Fe2+, Co2+, and Fe3+) and no significant interference was reported except Co2+, causing an interference only for sensor (2). Limit of Detection (LOD) measurements gave LOD values around 2.9 ppb, which is lower as compared to the threshold value in aqueous solution (4 ppb), determined by the World Health Organization (WHO). The response times of the sensors, estimated by UV–vis and fluorescence spectroscopy techniques, were found to be 0.7 s and 0.6 s, respectively. Owing to these short response times, the sensors can be included in the class of fast sensors when compared with other sensors given in the literature. The results prominently indicate that the sensors developed in this work are highly selective and sensitive to Be2+ and have a potential of usage in the detection of Be2+ in aqueous media.