A series of nine CoII, CuII, and CdII mixed-ligand coordination complexes with a 3,3′-dipyridyl connector 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) have been achieved, by changing the incorporated benzenedicarboxylic co-ligands from isophthalic acid (H2ip) to its 5-substituted derivatives 5-nitroisophthalic acid (–NO2, H2nip) and trimesic acid (–COOH, H3tma). All compounds have been structurally determined by the X-ray diffraction technique. It is indicated that most of them are coordination polymers, with the ligands of benzenecarboxylic acids being doubly deprotonated to compensate the charge and bridge the metal ions, except for a monomeric ion-pair product [Co(3-bpt)2(H2O)4]·(H2tma)2·(H2O)2 (1c). These polymers display a variety of coordination frameworks, such as 1-D double-strand chain, 2-D layer with (4,4) topology, 2-D double layer, 2-D layer with (6,3) topology and 1-D molecular ladder etc. The results evidently reveal the profound substituent effect of the R-isophthalate building blocks on engineering such coordination arrays, in virtue of the versatility of 3-bpt with diversiform configurations and binding fashions. Nevertheless, the choice of metal ion is also significant in the structural assembly, and the low-dimensional coordination networks are further extended to diverse 3-D supramolecular crystalline lattices via noncovalent interactions especially hydrogen bonding. Solid-state properties such as thermal stability and fluorescence have also been investigated.
A new family of ZnII and CdII coordination complexes 1–8 with a multifunctional building block trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (bpe) have been prepared at ambient conditions in water–methanol solution, by varying the auxiliary benzenedicarboxyl co-ligands from the familiar isophthalic acid (H2ip) and terephthalic acid (H2tp) to their derivatives 5-hydroxylisophthalic acid (H2hip) and tetrabromo-terephthalic acid (H2tbta). Single-crystal X-ray diffraction indicates that these complexes display a variety of coordination motifs, from the discrete mononuclear species (8) to infinite 1-D (1 and 7), 2-D (3, 5, and 6), and 3-D (2 and 4) metal–organic networks. Furthermore, extended supramolecular architectures are constructed for these complexes via predictable secondary interactions such as hydrogen bonding and aromatic stacking. A comprehensive structural analysis and comparison of 1–8 reveals that their crystalline lattices can be properly regulated by a selection of different metal ions (ZnII or CdII) and benzenedicarboxyl co-ligands, as well as the versatile building functionality of the bpe tecton , which can be readily involved in both coordination and secondary interactions. Notably, this work first demonstrates that bpe can also be applied as an angular bridging spacer by using both the 4- and 2-pyridyl groups to construct novel CdII coordination frameworks.
Nine 5-methylnicotinate (L–CH3−) coordination complexes, namely, {[Ni(L–CH3)2(H2O)2](H2O)}n (1), [Ni2(L–CH3)4(H2O)]n (2), Ni(HL–CH3)2Cl2 (3), [Cd2(L–CH3)2(SO4)(H2O)6]n (4), [Cd(L–CH3)2(H2O)]n (5), {[Cu(L–CH3)2(H2O)2](H2O)}n (6), {[Co(L–CH3)2(H2O)2](H2O)}n (7), [Mn(L–CH3)2(H2O)2]n (8), and [Pb(L–CH3)2]n (9), were synthesized with different metal salts. For complexes 1–3, the use of different NiII salts (SO42−, OAc−, or Cl−) leads to three distinct coordination motifs, including a 3D lvt framework, a 3D self-interpenetrating (3·4·5)(32·43·53·6·74·82) network, and a mononuclear species, respectively. For CdII, two different 1D chain complexes can be assembled from HL–CH3 with CdSO4 (4) and Cd(OAc)2 or CdCl2 (5). However, such an anion effect has not been observed for the CuII (6), CoII (7), MnII (8), and PbII (9) complexes, which show a 3D lvt network for 6 and 7, a 2D (4,4) layer for 8, and a 3D (3,5)-connected (4·62)(4·67·82) network for 9. These results demonstrate that the diverse coordination motifs for 1–9 (from 0D, 1D, 2D, to 3D) can be effectively adjusted by the metal-ligating tendency and metal-dependent counter-anion effect. Thermal stability and solid-state fluorescence have also been investigated.
This work focuses on coordination chemistry of a heteroalicyclic dicarboxylate ligand 5,6-dihydro-1,4-dithiin-2,3-dicarboxylate (L) with transition metals in the presence of N-donor co-ligands. A series of five CuII and MnII coordination complexes with L building blocks and different chelating/bridging co-ligands have been prepared, namely [Cu(L)(phen)]n (1), [Cu(L)(4bpy)(H2O)]n (2), {[Cu2(L)2(μ3-OH)](H2dabco)0.5(H2O)}n (3), {[Mn2(L)(phen)4](H2O)2(ClO4)2}2 (4), and {[Mn2(L)(2bpy)4](2bpy)0.5(ClO4)2}2 (5) (phen = 1,10-phenanthroline, 4bpy = 4,4′-bipyridine, dabco = 1,4-diazabicyclo[2,2,2]octane, 2bpy = 2,2′-bipyridine), in which the ligand L is obtained by an in situhydrolysis reaction of 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydride in the presence of lithium hydroxide. Single-crystal X-ray diffraction reveals that these complexes display a variety of coordination motifs, from the discrete tetranuclear species (4 and 5) to infinite 1-D arrays (1 and 3) and 2-D → 3-D polycatenated architecture (2), which are regulated by the multiple coordination modes of L. Furthermore, the introduction of auxiliary N-heterocyclic ligands plays a critical role in extending the dimensionality of these metallosupramolecular systems via coordination and/or secondary interactions such as hydrogen bonds and aromatic stacking. The magnetic properties and thermal stability of these complexes have also been investigated and discussed in detail.
A novel PtS-type porous Cu(II) complex, {[Cu3(dmtrz)2(OX)2(H2O)2]·8.5H2O}n (1) was synthesized through diffusion reaction, which showed single-crystal-to-single-crystal transformation during a reversible dehydration and rehydration process accompanied by a colour change.
Chlorine, bromine and iodine substituted derivatives of 5,5′-bisdiazo-dipyrromethane have been synthesized and their crystal structures were studied by X-ray crystallography. In the three structures, the 5,5′-bisdiazo-dipyrromethanes form interlocked dimers through quadruple N–H⋯N hydrogen bonds. The halogen⋯π synthons also provide a significant contribution to the resulting supramolecular motifs.
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