From lamellar net to bilayered-lamella and to porous pillared-bilayer: reversible crystal-to-crystal transformation, CO2 adsorption, and fluorescence detection of Fe3+, Al3+, Cr3+, MnO4–, and Cr2O72– in water

An aqua-coordinated lamellar net [Zn(5-NH2-1,3-bdc)(H2O)] (1, 5-NH2-1,3-H2bdc = 5-amino-1,3-benzenedicarboxylic acid) has been found to proceed a reversible stimuli-responsive 2D-to-2D crystal-to-crystal transformation with a water-free bilayered-lamellar net [Zn(5-NH2-1,3-bdc)] (1′) upon removal and rebinding of aqua ligands, whereas a 2D porous pillared-bilayer [Zn2(5-NH2-1,3-bdc)2(NI-bpy-44)]∙DMF (2, NI-bpy-44 = N-(pyridin-4-yl)-4-(pyridin-4-yl)-1,8-naphthalimide) has been engineering tailored by introducing NI-bpy-44 to replace the coordinated aqua ligands. Pillared-bilayer 2 displayed moderate CO2 uptakes of 79.1 cm3 g–1 STP at P/P0 = 1 and 195 K with an isosteric heat of CO2 adsorption (Qst) of 37.0 kJ mol–1 at zero-loading. Noteworthy, the water suspensions of 1 and 2 both showed good fluorescence performances, which were effectively quenched by Fe3+, MnO4–, and Cr2O72– ions and shifted to long wavelength by Fe3+, Al3+, and Cr3+, even with the coexistence of equal-amount of most other interfering ions. Taken Stern–Volmer quenching constant, limit of detection, quenching efficiency, anti-interference ability, and visual observation into consideration, it is clear that 1 and 2 both are promising excellent fluorescence sensors for highly sensitive detection of Fe3+, MnO4–, and Cr2O72–.