Optical sensors for detection of nano-molar Zn2+ in aqueous medium: Direct evidence of probe- Zn2+ binding by single crystal X-ray structures

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2019-01, Vol.368, p.52-61
• Main Authors: Mahiuddin, Md, Banerjee, Mahuya, Shaikh, Ahad, Shyam, Tandrim, Taniya, Seikh, Ghosh, Avijit, Adhikary, Arghya, Brandão, Paula, Félix, Vítor, Das, Debasis
• Format: Article
• Language: English
• Subjects: Bare eye; Cell imaging; Crystal structure; Fluorescence; Nano-molar; Sensors; Zn2
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2018.09.009

Nano-molar level optical detection of Zn2+ is established by spectroscopic techniques and confirmed by single crystal X-ray structures of resulting Zn2+ complexes. Intra-celullar Zn2+ imaging in HeLa and MDA-MB-468 cells have been achieved. DFT studies unveil the energy parameters involved in probe- Zn2+ interaction. [Display omitted] •Single crystal X-ray structural evidence of Zn2+ binding.•Nano-molar level optical detection of Zn2+ in aqueous medium.•Intra-celullar imaging of Zn2+ in HeLa and MDA-MB-468 cells.•DFT studies unveil the energy parameters involved in probe- Zn2+ interaction. Two simple probes, derived by condensation of ethylenediamine with 3-ethoxysalicylaldehyde (L) and salicylaldehyde (L1) have been exploited for selective recognition of Zn2+. The interaction between probes and Zn2+ has been established by spectroscopic techniques and confirmed by single crystal X-ray structures of the resulting Zn2+ complexes. It is proposed that Zn2+ inhibits the PET process, originally responsible for non-emissive nature of free ligand and turns the fluorescence ON through CHEF process. The L and L1 probes respectively detect as low as 1.8 nM and 1.16 nM Zn2+, while corresponding binding constants are 2.9 × 106 M−1 and 4.57 × 105 M−1. L1 is very effective for intra-celullar imaging of Zn2+ in HeLa and MDA-MB-468 cells. The density functional theoretical studies unveil the energy parameters involved in the probe-Zn2+ interaction process.