ABSTRACT
Luminescent materials play an important role in anticounterfeiting applications due to their superior properties of visual convenience and high concealment. However, traditional luminescent materials usually exhibit monochromatic emission and are easily counterfeited. Therefore, in this work, we report a multicolor long persistent luminescence (PersL) material, NaCa2GeO4F:Tb3+ (abbreviated as NCGOF:Tb3+), where the color of PersL can be tuned from blue to cyan and bright green by changing the concentration of Tb3+, and the afterglow (concentration) can last for 5.62 h (0.1%), 8.52 h (0.4%) and 7.14 h (0.8%) at the corresponding concentrations of Tb3+, respectively. Investigation revealed that the multicolor PersL is essentially associated with the opportune traps and cross-relaxation effect of Tb3+ in NCGOF. Based on the unique features of PersL, anticounterfeiting devices have been fabricated, and the results indicate that their multicolor features can be easily detected using a portable ultraviolet lamp, and that they are impossible to counterfeit using any substitute so far, meaning that they provide a high level of security for use in practical applications.
ABSTRACT
A novel chemosensor 2-((Z)-(((E)-quinolin-2-ylmethylene)hydrazono)methyl)phenol PX has been successfully designed and synthesized, which showed both colorimetric and "turn-on" fluorescence responses for CN- in DMSO/H2O (3:2, v/v; pH=7.20) solution. The sensor could respond effectively to the stimulation of CN- ions via deprotonation and sensing mechanism of intramolecular charge transfer (ICT). Moreover, the sensor PX was successfully utilized to detect CN- in bitter almond, and the detection limit on fluorescence response of PX towards CN- was down to 4.5×10-7M. Test strips containing PX were also prepared, which could act as a practical colorimetric tool to detect CN- in aqueous media.
ABSTRACT
In this paper, we have designed and synthesized a novel sensor L1 based on asymmetric double-azine derivatives, which showed both "naked eye" recognition and fluorescence responses for CN- in DMSO/H2O (v/v=4:1, pH=7.20) solution. This simple sensor L1 could distinguish CN- from coexisting anions via the way of deprotonation and sensing mechanism of intramolecular charge transfer (ICT), and the minimum detection limit on fluorescence response of the sensor L1 towards CN- was down to 9.47×10-7M. Moreover, we have successfully utilized the sensor L1 to detect CN- in bitter almond. Test strips containing L1 were also prepared, which could act as a practical colorimetric tool to detect CN- in aqueous media.
