Structural variation from linear, layer to 3D framework: Syntheses, structures and luminescence

Abstract

Self‐assembly of Zn (II) or Cd (II) nitrates, flexible bis (pyridyl)‐diamine, as well as arenesulfonic acids, leads to the formation of ten coordination polymers, namely, [Zn(L1)(H2O)3]·2(p‐TS)·2H2O (1), [Zn(L1)(H2O)2]·2(p‐TS)·2H2O (2), [Zn(L1)2(p‐TS)2] (3), [Zn(H2L1)(H2O)4]·2(1,5‐NDS)·2H2O (4), [Zn(H2L2)(H2O)4]·2(1,5‐NDS)·4MeOH (5), [Cd(L1)(p‐TS)(NO3)]·H2O (6), [Cd(L1)(1,5 ‐NDS)0.5(H2O)]·0.5(1,5‐NDS)·H2O (7), [Cd(L2)(H2O)2]·(p‐TS)·(NO3)·3H2O (8), [Cd(L2)(1,5‐NDS)] (9) and [Cd(L2)(1,5‐NDS)]·MeOH (10) (L1 = N,N′‐bis (pyridin‐4‐ylmethyl) ethane‐1,2‐diamine, L2 = N,N′‐bis (pyridin‐3‐ylmethy l)ethane‐1,2‐diamine, p‐HTS = p‐toluenesulfonic acid, 1,5‐H2NDS = 1,5‐naphthalene disulfonic acid), which have been characterized by elemental analysis, IR, TG, PL, powder and single‐crystal X‐ray diffraction. Complexes 1, 4, 5 and 6 present linear or zigzag chain structures accomplished by the interconnection of adjacent M (II) cations through L1 ligands or protonated H2L12+/H2L22+ cations, while complexes 2, 3 and 8 show similar (4,4) layer motifs constructed from the connection of M (II) cations through L1 and L2. The same coordination modes of L1 and L2 in complexes 7 and 9 join adjacent Cd (II) cations to form double chain structures, which are further connected by bis‐monodentate 1,5‐NDS2− dianions into different (6,3) and (4,4) layer motifs. The L2 molecules in complex 10 join adjacent Cd (II) cations together with 1,5‐NDS2− dianions to form 3D network with hxl topology. Therefore, the diverse coordination modes of the bis (pyridyl) ligand with chelating spacer and the feature of different arenesulfonate anions can effectively influence the architectures of these complexes. Luminescent investigation reveals that the emission maximum of these complexes varies from 374 to 448 nm in the solid state at room temperature, in which complexes 4, 5, 7, 9 and 10 show average luminescence lifetimes from 7.20 to 14.82 ns. Moreover, photocatalytic properties of complexes 7–10 towards Methylene blue under Xe lamp irradiation are also discussed.