posted on 2022-01-20, 18:07authored byAkashdeep Nath, Gegari M Thomas, Shivali Hans, Sivaranjana Reddy Vennapusa, Sukhendu Mandal
A soft
acid-soft base interaction is highly predictable. However,
we demonstrate how the crystal packing of the newly synthesized zinc
framework [Zn2(5-AIA)2(DPTTZ)]·DMF (where
5-AIA = 5-aminoisophthalic acid, DPTTZ = N,N′-di(4-pyridyl)thiazolo-[5,4-d]thiazole, DMF = N,N′-dimethylformamide) directs an unexpected interaction
between the soft acid Hg(II) and the hard base oxygen instead of having
a soft center like nitrogen and sulfur in the system attributed to
a strong solvent interaction and a favorable ionic radius of Hg(II)
ion for oxygen chelation. This engenders selective Hg(II) ion sensing
through a “turn-off” emission quenching in water (limit
of detection = (2.174 ± 0.06) × 10–9 M)
along with natural water resources and in a broad pH range. A quantum-chemical
calculation elucidates the turn-off quenching mechanism and favorable
Hg(II) interaction with encompassed oxygen atoms inside the framework.