Synthesis, crystal structures, luminescence and magnetic property of two complexes based on 5-nitroisophthalic acid

Based on 5-nitroisophthalic acid (5-H 2 nip) and bis(4-pyridyl)amine (dpa), the complexes {[Cd 6 (5-nip) 6 (dpa) 4 ]·EtOH} n ( 1 ) and [Co 5 (5-nip) 2 (dpa) 2 (OH) 2 (SO 4 ) 2 (H 2 O) 2 ] n ( 2 ) have been synthesized and characterized by elemental analysis, single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetry analysis, fluorescence and magnetic susceptibility. The carboxylate groups of the 5-nip 2− adopt three different bridging modes [ bis (chelate-bidentate), bis (bidentate) and bis (monodentate)]. The 5-nip 2− anions and dpa play as linkers, which connect Cd(II) or Co(II) ions to form the three-dimensional structures of 1 and 2 . Moreover, 1 exhibits intense solid-state luminescence emissions centered at 402 nm at room temperature, which mainly originates from the intraligand π – π* transitions of 5-nip 2− . Magnetic susceptibility measurement indicates that 2 shows antiferromagnetic interactions between the Co(II) ions.