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Abstract: Molecular structural mechanics based finite element method is applied to study the influence of the two types of Stone–Wales defects on the elastic properties of monolayer and multilayer graphene nanofilms. Models with spatial frame structures are developed to simulate the graphene crystal with Stone–Wales defects based on the linkage between the inter-atomic potential energy in molecular mechanics and the strain energy in classical structural mechanics. Several possible influencing factors, including the number and types of Stone–Wales defects, the distance between two defects and the position of defects in the graphene, are taken into account to evaluate Young''s moduli and Poisson''s ratios of armchair and zigzag monolayer graphene nanofilms. It is shown that the Stone–Wales defects have remarkable influence on the elastic properties of monolayer graphene. In addition, the size-dependent Young''s moduli and Poisson''s ratios of multilayer graphene nanofilms are also investigated when the Stone–Wales defects in surface layers are taken into consideration. [Copyright &y& Elsevier]

Abstract: This work presents six CuII, CoII, and NiII supramolecular complexes assembled from a bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and R-isophthalic acids (R =–CH3 for 5-methylisophthalic acid or R =–OCH3 for 5-methoxyisophthalic acid), which have been prepared using the layer-separation diffusion method and fully characterized by IR, elemental analysis, and powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates that these complexes show 1-D tube-like (for CuII complexes 1 and 2) or discrete cage-like dinuclear (for CoII and NiII complexes 3–6) coordination patterns. Furthermore, extended 3-D supramolecular architectures are constructed via secondary interactions between the coordination arrays, and three types of packing fashions are observed for the dinuclear species 3–6. Structural diversification for these complexes can be properly attributed to the inherent discrepancy of metal ions and the substituent effect of R-isophthalate tectons. [Copyright &y& Elsevier]

Abstract: Assemblies of an angular dipyridyl ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo) with a series of metal perchlorate afford five new supramolecular complexes with the general formula of [M(4-bpo)2(H2O)4]·(4-bpo)2 ·(anion)·(solvent), in which M=MnII for 1, FeII for 2, CoII for 3, ZnII for 4, and FeIII for 5. Although similar molecular structures and compositions are found for these mononuclear complexes, they display two types of supramolecular lattices. Complexes 1, 4 and 5 similarly crystallize in space group P2/n or P2/c. The complex cations, free 4-bpo and lattice water are linked to generate 2D layered frameworks with the aid of hydrogen bonding, and the counter anions are located within and between (also methanol in 5) these 2D arrays. However, complexes 2 and 3 are isostructural in space group . Two types of alternate 2D layers consisting of complex cations and free 4-bpo components, respectively, are observed with the anions and lattice water locating between them. These motifs are interlinked by complicated hydrogen-bonding to form a 3D intercalated network. Moreover, when Co(NO3)2 is used instead of Co(ClO4)2 in the assembly of 3, a 1D polymeric chain complex {[Co(4-bpo)(H2O)2(NO3)2](H2O)3} n (6) is generated. These results indicate that the choice of metal ion and anion exerts a significant influence on governing the target complexes. A comparison of the structural features for all metal perchlorate complexes with 4-bpo is also briefly discussed. [Copyright &y& Elsevier]