Guanidine-based dual-responsive ̀turn on ́ fluorometric probes for the selective detection of Zn2+ cation and F ̅ anion: Spectral and theoretical investigations, smartphone-assisted colorimetric detection, and applications in bio-imaging of Artemia salina animal model and molecular logic gate operation

Abstract

Two dual-responsive probe molecules 1,3-bis(5-bromo-2-hydroxyphenyl methylideneamino)guanidine hydrochloride (P1) and 1,3-bis(3-ethoxy-2-hydroxyphenyl methylideneamino)guanidine hydrochloride (P2) have been synthesized for the detection of inorganic ions in solution at room temperature. These dual-responsive sensor molecules showed colorimetric responses toward Cu2+ and Fe3+ cations, and F @#x0305; anion, and also demonstrate the ̀turn on ́ fluorometric responses to Zn2+ cation and F @#x0305; anion in CH₃CN:DMSO (9:1, v/v) solution. The probe molecules demonstrated reversible binding to Zn2+ cation in the presence of EDTA, thus enhancing its versatility. The smartphone-based RGB analysis validated the rapid colorimetric on-site detection Zn2⁺ cations using probes coated test strips. The density functional theory calculations elucidate the nature of interaction between probe molecules and the sensed ions. The probes were successfully employed for Zn2+ and F @#x0305; detection in in vitro bio-imaging of HaCaT and MDA-MB-231 cell lines and in vivo imaging of Artemia salina nauplii. Furthermore, they have been employed for the construction of an INHIBIT molecular logic gate, facilitating precise monitoring for various analytical and biomedical applications.