Tuning of Valence States, Bonding Types, Hierarchical Structures, and Physical Properties in Copper/Halide/Isonicotinate System

Seven cupric halide coordination
polymers, namely [Cu5(OH)3­Br3(ina)4] (1), [Cu5(OH)3­Cl3(ina)4] (2), [Cu2(OH)­Cl­(ina)2]
(3), [Cu3(OH)2­Cl2(ina)2]·2H2O (4), [Cu3(OH)2­Br2(ina)2]·2H2O (5), [Cu2Cl2­(ina)2(H2O)2] (6), [Cu2Cl­(ina)2­(gca)­(H2O)] (7),
cupric complex templated cuprous halide [CuII(Me-ina)2(H2O)]­[CuI5Br7] (8), and organic templated cuprous halide Me2-ina­[Cu2Br3] (9) (Hina = isonicotinic
acid), were prepared from the starting materials of cupric halide
and Hina via fine-tuning solvothermal reactions. According to valence
states of copper, 1–7 are copper­(II)
complexes, 8 is a mixed-valent Cu­(I,II) complex, while 9 is a Cu­(I) compound. According to bonding types of halides,
nine complexes can be classified as three types: complexes 1–3 include only normal X–Cu bond (X =
halide); complexes 4–7 include normal
X–Cu bond and X···Cu weak bond; complexes 8 and 9 include normal X–Cu bond and X···H–C
halogen hydrogen bonds. Complexes 1 and 2 are isomorphic three-dimensional (3D) pcu topological metal organic
frameworks (MOFs) with butterfly-like Cu4(μ3-OH)2X2 and steplike Cu6(μ3-OH)4 cores as nodes, showing strong ferromagnetic
couplings. Complex 3 also is a pcu topological MOF with
only butterfly-like Cu4(μ3-OH)2Cl2 clusters as nodes, presenting spin canting antiferromagnetic
behavior. Isostructural 4 and 5 are Cu3(OH)2 clusters based two-dimensional (2D) (4,4)
layers, which are extended into 3D eight-connected networks via weak
Cu···X bonds, showing ferromagnetic coupling. Antiferromagnetic 6 is a simple one-dimensional coordination polymer, which
is extended via weak Cu···Cl bonds into 3D (3,4)-connected
networks. Paramagnetic 7 is a ladderlike polymer, which
is extended into 2D (3,4)-connected layer via weak Cu···Cl
bonds. The syntheses of polymeric cupric complexes 1–7 mainly result from differences in reactant ratio and pH
value. Utilization of reducing methanol generated novel cubane-containing
[Cu5Br7]2– chain templated
by paddlewheel-like [CuII(Me-ina)2]2+ 8 and face-shared dimer-containing [Cu2Br3]− chain templated by N-methylated and O-esterificated
Me2-ina 9. Complex 9 exhibits
a strong red emission and a weaker green emission upon excitation.