Five Cd(II) metal–organic
frameworks (MOFs), [Cd(HL)
2
] (
1
), [Cd(HL)
2
(H
2
O)
2
] (
2
), [Cd
3
(HL)
2
(obda)
2
] (
3
), [Cd
2
(HL)
2
(ohmbda)(DMA)(H
2
O)] (
4
),
and [Cd
2
(HL)(btc)(H
2
O)
2
]·3H
2
O (
5
), were prepared
by reactions of Cd(NO
3
)
2
·4H
2
O with 1-(1
H
-imidazol-4-yl)-4-(4
H
-tetrazol-5-yl)benzene (H
2
L) or mixed carboxylate ancillary
ligands of 1,2-benzenedicarboxylic acid (H
2
obda), 5-hydroxy-1,3-benzenedicarboxylic
acid (H
2
ohmbda), and 1,3,5-benzenetricarboxylic acid (H
3
btc), respectively. Their structures have been characterized
by single-crystal X-ray diffraction, elemental analysis, infrared
spectroscopy (IR), thermogravimetric analysis, and powder X-ray diffraction.
Compounds
1
and
2
are supramolecular isomeric
frameworks without consideration of the solvent molecules. Complex
1
exhibits a binodal (3, 5)-connected two-dimensional (2D)
layer structure with the point (Schläfli) symbol of (5
2
·6)(5
5
·6
4
·7), while complex
2
shows a 2D + 2D → 3D (three-dimensional) framework.
Complex
3
is a (3, 5, 6)-connected tetranodal 3D net
with the point (Schläfli) symbol of (4·8
2
)
2
(4
5
·6·8
4
)
2
(4
5
·6
5
)
2
(4
8
·6
6
·8). Compound
4
is a (3, 3, 8)-connected
trinodal 3D net with the point (Schläfli) symbol based on a
binuclear [Cd
2
N
2
O] subunit, while
5
is a 2-nodal (3, 4)-connected 2D V
2
O
5
-type
network based on [Cd
2
N
2
(COO)
2
] SBU.
The studies of molecular sensing properties show that the luminescent
MOFs can be employed as fluorescent sensors for the detection of Fe
3+
and nitro compounds. Compound
1
and
3
exhibit quenching responses for Fe
3+
in dimethylformamide
solution with detection limits of 2.3 × 10
–6
an...
