A new highly Selective, sensitive and NIR spectrophotometric probe based on A2B2-Type of unsymmetrical phthalocyanine for hazardous Be2+ recognition.

The aim of this work is to construct a new A2B2-type of unsymmetrical and ratiometric phthalocyanine (Pc) based-probe O-A2B2ZnPc to provide an effective solution to critical inadequacy to be experienced for the detection of hazardous Be2+. O-A2B2ZnPc enabling strong absorption and emission in Near-Infrared region (λabs-λem wavelengths of 694-712 nm) showed excellent selectivity and sensitivity toward Be2+ among competitive metal ions by both spectrophotometric and fluorometric methods. The probe with oligomeric Pc form in THF was degraded with the addition of aqueous Be2+ and arranged to J-aggregation form, resulting in a remarkably diminishing in Q-band at 694 nm as well as a new band formation at 746 nm, and a considerably decreasing in fluorescence emission. The probe has superior features for the determination of Be2+ such as high quantum efficiency and photochemical stability, rapid response (1 s), high selectivity and very low Limit of Detection (0.26 ppb and 1.5 ppb) for UV-Vis and fluorescence, respectively which are quite good values according to the permissible amount of Be2+ (4 ppb) in water as specified by World Health Organization. O-A2B2ZnPc can be shown among the best performing probes with its unique properties according to previous studies in the literature. In addition, the geometrical and spectral features of the O-A2B2ZnPc were analyzed in detail by DFT calculations.