Abstract:
Two new 3D, Zn(II)–organic frameworks, [{Zn(BINDI)0.5(bpa)0.5(H2O)}·4H2O]n (MOF1) and
[{Zn(BINDI)0.5(bpe)}·3H2O]n (MOF2) (where H4BINDI = N,N’-bis(5-isophthalic acid)naphthalenediimide,
bpa = 1,2-bis(4-pyridyl)ethane and bpe = 1,2-bis(4-pyridyl)ethylene), have been successfully synthesized
by room temperature self-assembly and structurally characterized. Both MOF1 and 2 show 2-fold interpenetrated 3D framework structures with 1D channels of dimensions 4.4 × 9.5 and 4.6 × 2.5 Å2 respectively.
Gas adsorption studies of the MOFs revealed selective and higher CO2 uptake properties of MOF1 over 2
owing to the presence of a polar pore surface and an optimum pore size of 1 for CO2 gas molecules.
Furthermore, the high water stability and luminescence properties of MOF1 and 2 were exploited for
sensing of nitroaromatic pollutants in water. Consequently, both the MOFs exhibit highly selective
aqueous-phase sensing of 2,4,6-trinitrophenol (TNP) through a luminescence quenching mechanism.
Furthermore, MOF1 exhibits a relatively higher efficiency of TNP detection (LOD = 0.6 ppm, Ksv = 4.9 ×
104 M−1
) compared to 2 (LOD = 1.5 ppm, Ksv = 1.29 × 104 M−1
) due to higher resonance energy transfer
between MOF1 and TNP owing to their better spectral overlap. Herein, the influence of N,N’-donor
spacers on the structure, selective gas adsorption and the sensing properties of two new Zn(II) MOFs has
been demonstrated.
