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Two double-stranded metallo-triangles, Dy9 and Dy24, with hexaple-C10H7PO32− bridges were constructed, and their magnetic properties were explored. Compared with the field-induced relaxation phenomenon of Dy9 templated with a chloride anion, Dy24 templated with a sodium cation exhibited zero-field single-molecule-magnet behavior. [ABSTRACT FROM AUTHOR]

Constructing chiral luminescent systems with both large luminescence dissymmetry factor (glum) and high luminous efficiency has been considered a great challenge. We herein describe a highly efficient approach to sterically stabilize the helical configurations of carbo[5]helicenes for improved CPL properties in a series of π-donor and π-acceptor substituted [5]helicenes (1, 2, 3, 4 and 5). Enabled by the ortho-installation of methyl groups as well as the steric effects of triarylamine (Ar3N) and triarylborane (Ar3B) handles in meta-substituted [5]helicenes, their optical resolution into enantiomers has been accomplished using preparative chiral HPLC. The molecular chirality of [5]helicenes can be transferred to Ar3B and Ar3N as light emitters, which allowed further investigations of their chiroptics, including optical rotation, circular dichroism (CD) and circularly polarized luminescence (CPL). Remarkably, 4 has been demonstrated to display dramatically enhanced CPL performance with a much larger glum (>1.2 × 10−2) and an increased emission quantum efficiency (ΦS = 0.75) compared with the other analogues, as a result of the isomeric tuning of substitutions with differential steric and electronic effects. These experimentally observed CPL activities were rationalized by TD-DFT computations for the angle (μ,m) between electric and magnetic transition dipole moments in the excited states. In addition, the conspicuous intramolecular donor–acceptor charge transfer led to thermal responses in the emissions of 2 and 4 over a broad temperature range. [ABSTRACT FROM AUTHOR]

This paper reports a quasilinear hydrazone-based mononuclear dysprosium(III) compound, namely, {Dy(Hppyh)2(SCN)3}·2MeOH (I), where Hppyh is pyrazine-2-carboxylic acid pyridin-2-ylmethylene-hydrazide. Compound I behaves as a single-ion magnet (SIM) based on the optimal dc field application of 0.7 kOe, showing a complex magnetic relaxation phenomenon with a tunneling relaxation time of 6.1 ± 0.3 × 10−3 s and an effective spin reversal barrier of 22.6 ± 1.1 K for the low- and high-frequency regions, respectively. More importantly, detailed comparative experimental and theoretical investigations reveal that the complex magnetic relaxation was most likely associated with the single DyIII ion behavior as well as the short-range intermolecular magnetic dipolar interactions. [ABSTRACT FROM AUTHOR]

This paper reports two closely related heteropentanuclear manganese complexes, namely, {Na2Mn3(opch)3(μ4-O)(μ2-N3) (μ2-AcO)(μ2-MeO)}·6CH3OH·0.5H2O (1) and {Na2Mn3(opch)3(μ4-O)(μ2-N3)2(μ2-AcO)}·2.5CH3OH·2H2O (2), where H2opch is (E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide. Single-crystal X-ray diffraction analysis reveals that the trigonal bipyramidal skeletons in both complexes are comparable, where a perfect triangular Mn3 motif occupies the equatorial plane. Magnetic investigations suggest that overall antiferromagnetic coupling is present within the triangles of 1 and 2. However, their dynamic magnetic properties are drastically distinct. Indeed, complexes 1 and 2 show two kinds of dual slow magnetic relaxation processes that correspond to anisotropy barriers (Δ) of 9.2 cm−1 (11.4 cm−1 for 2) and 12.8 cm−1 (30.0 cm−1 for 2) for the low- and high-frequency domains, respectively. More importantly, a further comparative study of the structure and magnetism indicates that the coordination sphere of these two model complexes with the homologous hydrazone-based coordination sites undergoes an alteration from methoxide-O to azide-N upon a subtle change of the auxiliary anion accompanied by modulating octahedron geometries, leading to a further influence on different relaxation dynamics. [ABSTRACT FROM AUTHOR]

A new CuII-azide complex, {(C4H12N2)[Cu5(N3)12]·4H2O} n, has been synthesized by the reaction of piperazine, Cu(OAc)2·2H2O (OAc is acetate) and NaN3. In the structure, μ2-1,1- and μ3-1,1,1-azide anions bridge five CuII cations to form a linear pentanuclear cluster unit, which is further linked by μ2-1,1- and μ2-1,3-azide anions to form a two-dimensional condensed [Cu5(N3)12] n layer. The diprotonated piperazine and the solvent water molecules are hydrogen bonded to the coordination layers to form a three-dimensional supramolecular network. [ABSTRACT FROM AUTHOR]

The title compound, [CuMo4O13(C21H15N3)2] n, was synthesized by the reaction of ammonium molybdate, copper acetate and 4-[3,5-bis(pyridin-4-yl)phenyl]pyridine (DPPP) in an aqueous medium under hydrothermal conditions. The two unique molybdenum centers and the copper center adopt MoO4 tetrahedral, MoO5N octahedral and CuO4N2 octahedral geometries, respectively. These polyhedra are connected to each other through corner-sharing to form a two-dimensional Cu-Mo-O layer, which is further linked by the DPPP ligands to form the three-dimensional inorganic-organic hybrid framework. [ABSTRACT FROM AUTHOR]

Crystals of the title compound {(H2pip) [Cu5(N3)12] ·4H2O}n (pip: piperazine) are synthesized by slow diffusion between an aq. [ABSTRACT FROM AUTHOR]

Constructing chiral luminescent systems with both large luminescence dissymmetry factor ( g lum ) and high luminous efficiency has been considered a great challenge. We herein describe a highly efficient approach to sterically stabilize the helical configurations of carbo[5]helicenes for improved CPL properties in a series of π-donor and π-acceptor substituted [5]helicenes (1, 2, 3, 4 and 5). Enabled by the ortho -installation of methyl groups as well as the steric effects of triarylamine (Ar 3 N) and triarylborane (Ar 3 B) handles in meta -substituted [5]helicenes, their optical resolution into enantiomers has been accomplished using preparative chiral HPLC. The molecular chirality of [5]helicenes can be transferred to Ar 3 B and Ar 3 N as light emitters, which allowed further investigations of their chiroptics, including optical rotation, circular dichroism (CD) and circularly polarized luminescence (CPL). Remarkably, 4 has been demonstrated to display dramatically enhanced CPL performance with a much larger g lum (>1.2 × 10 -2 ) and an increased emission quantum efficiency ( Φ S = 0.75) compared with the other analogues, as a result of the isomeric tuning of substitutions with differential steric and electronic effects. These experimentally observed CPL activities were rationalized by TD-DFT computations for the angle ( θ μ,m ) between electric and magnetic transition dipole moments in the excited states. In addition, the conspicuous intramolecular donor-acceptor charge transfer led to thermal responses in the emissions of 2 and 4 over a broad temperature range.

This paper reports two closely related heteropentanuclear manganese complexes, namely, {Na 2 Mn 3 (opch) 3 (μ 4 -O)(μ 2 -N 3 ) (μ 2 -AcO)(μ 2 -MeO)}·6CH 3 OH·0.5H 2 O (1) and {Na 2 Mn 3 (opch) 3 (μ 4 -O)(μ 2 -N 3 ) 2 (μ 2 -AcO)}·2.5CH 3 OH·2H 2 O (2), where H 2 opch is ( E )- N '-(2-hydroxy-3-methoxybenzylidene)pyrazine-2-carbohydrazide. Single-crystal X-ray diffraction analysis reveals that the trigonal bipyramidal skeletons in both complexes are comparable, where a perfect triangular Mn 3 motif occupies the equatorial plane. Magnetic investigations suggest that overall antiferromagnetic coupling is present within the triangles of 1 and 2. However, their dynamic magnetic properties are drastically distinct. Indeed, complexes 1 and 2 show two kinds of dual slow magnetic relaxation processes that correspond to anisotropy barriers ( Δ ) of 9.2 cm -1 (11.4 cm -1 for 2) and 12.8 cm -1 (30.0 cm -1 for 2) for the low- and high-frequency domains, respectively. More importantly, a further comparative study of the structure and magnetism indicates that the coordination sphere of these two model complexes with the homologous hydrazone-based coordination sites undergoes an alteration from methoxide-O to azide-N upon a subtle change of the auxiliary anion accompanied by modulating octahedron geometries, leading to a further influence on different relaxation dynamics.

In the title compound, {[Zn(C(4)H(4)O(6))(H(2)O)]·2H(2)O}(n), the l-tartrate ligands adopt μ(4)- and μ(2)-coordination modes. The Zn(II) atom adopts an octa-hedral geometry and is chelated by two kinds of l-tartrate ligands through the hydr-oxy and carboxyl-ate groups and coordinated by one unchelating carboxyl-ate O atom and one water mol-ecule. In the crystal, the l-tartrate ligands link the Zn(II) atoms, forming a two-dimensional coordination layer; these layers are futher linked into a three-dimensional supra-molecular network by O-H⋯O hydrogen bonds between the two-dimensional coordin-ation layers and the uncoordinated water mol-ecules. The latter are equally disordered over two positions.