Pore environment modulation with
polarizing groups is one of the
essential prerequisites for selective carbon dioxide (CO2) adsorption in metal–organic frameworks (MOFs), wherein judicious
installation of the photocatalytic feature can promise visible light-triggered
degradation of toxic organic dye molecules. However, astute amalgamation
of both these attributes over a single MOF is rather rare, yet much
anticipated in view of sustainable applications. Pore engineering
is effectively harnessed in a Zn(II)-based three-dimensional (3D)
MOF, CSMCRI-16 (CSMCRI = Central Salt and Marine Chemicals
Research Institute), through mixed-ligand assembly of a N-rich linker
(L), 4,4′-oxybis(benzoic acid) (H2oba)
ligand, and [Zn2(CO2)4N2] paddle-wheel secondary building units (SBUs). The noninterpenetrated
structure contains unbound nitrogen and accessible oxygen atom-decorated
porous channels and exhibits admirable stability in diverse organic
solvents, open air, and at elevated temperatures. The heteroatom-decorated
porous channels facilitated excellent CO2 uptake in the
activated MOF (16a) with high selectivity over N2 (CO2/N2: 155.3) at 273 K. The framework
further exhibits reasonable CO2 affinity and multicyclic
CO2 sorption recurrence without a significant loss in the
uptake capacity. Benefitting from the presence of the [Zn2(CO2)4N2] cluster in conjugation
with π-conjugated organic ligands, the extended 3D network revealed
an optical band gap energy of 2.55 eV, which makes the MOF an efficient
photocatalyst toward the degradation of the cationic dyes crystal
violet (CV) and methylene blue (MB) in the presence of a simple 40
W visible light lamp without any assistance of external oxidants.
The catalyst exhibits multicyclic performance and short reaction time
in addition to the fact that catalytic efficiencies (CV: 97.2%, MB:
97.8%) are comparable to those of contemporary materials.