Five new coordination polymers, {[Co-(OAc) 2 (bpe)(H 2 O)]•0.5(dmf)} n (1), {[Co(bpy) 2 (H 2 O) 4 ]-[Co(tfa)(bpy) 2 (H 2 O) 3 ](tfa) 3 •1.5(bpy)} n (2), [Co-(tfa) 2 (dps) 4 ] n (3), {[Co(tfa) 2 (bpe) 4 ]•H 2 O} n (4), and [Co-(tfa) 2 (bpp) 4 ] n (5) (where AcO − = CH 3 CO 2 − ; tfa − = CF 3 CO 2 − ; bpy = 4,4′-bipyridine; bpe = 1,2-bis(4-pyridyl)ethane; bpp = 1,3-bis(4-pyridyl)propane; dps = 4,4′-dipyridyl sulfide; dmf = N,N′-dimethylformamide) were synthesized by the reactions of Co(OAc) 2 •4H 2 O and Co(tfa) 2 •4H 2 O with different dipyridyl ligands and characterized by elemental analysis, IR spectra, and X-ray single-crystal diffraction. Compound 1 exhibits extended two-dimensional (2D) networks through the bridging AcO − and bpe ligands. The polymeric motifs in 2−5 are exclusively based on bipyridine-type ligands and results in 1D cationic chains in 2, similar charge-neutral double tapes in 3 and 4, and a 2D polymeric network in 5. In 2−5, the tfa anions coordinate to the Co(II) center in a monodentate mode. An impact of the anion's fluorination on coordination modes and supramolecular architectures is registered. Magnetic measurements reveal almost vanishing exchange interactions in the layered materials 1 and 5. The correlation of mechanical properties and crystal structure has been demonstrated for 1.
The mechanical features of catena-{(μ 2 -adipato-O,O′)-bisIJpyridine-4-aldoxime)-copperIJII)} (1) were studied by the nanoindentation technique under different loads. The newly synthesised metal-organic material 1, with a one-dimensional coordination backbone, revealed plastic deformation evidenced by the sliding steps and nanoindentation load-displacement curves and the lack of cracks inside the indentations and in its neighborhood at all load tests. The pattern of the material movement in the crystal volume and its transfer to the surface associated with the shear-induced breakage of weak interlayer forces and the breakage of hydrogen bonds within the H-bonded layer is suggested.
In this work, the strain rate effect on the deformation processes under Berkovich indentation of Tbdoped aluminophosphate glass has been investigated. It is shown that both densification and shear flow, adopted as main mechanisms of plastic deformation for oxide glasses, are strain rate sensitive. Moreover, the shear flow is assumed to be responsible for the strain rate sensitivity of densification. The densification contribution to the total plastic deformation is found to be greater for lower strain rate, and the same tendency is observed for the plastic flow. This, in turn, leads to the influence of the strain rate on the hardness values, manifesting as a softening of the glassy matrix with the decrease of strain rate caused by more intensive development of the densification and shear flow. The decrease of hardness with load increase is attributed to the involving and increasing contribution of the shear flow and fracture to the total deformation process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.