[en] The transport properties of the three scenarios of the strained graphene magnetic barriers, where the first one is composed of the strained stripe in the positive magnetic field and the pristine stripe in the negative magnetic field on the left and right sides respectively, the second one is just the result of exchanging the stripes in the first one, and the last one contains the fully strained stripes on both sides, have been investigated. It is found that the first two configurations own the same evolution behavior both in transmission and conductance versus the strain, the joint contributions from the strains in the first two configurations lead to the enhancement both in transmission and conductance in the third one. The strain tends to devastate the regular shape of the energy bands within the scope of higher momentum/energy, where the more severe damage is observed in the superlattices with the fully strained periodic unit cell. The uniformity of the periodic unit between the left and right stripes in the third scenario makes the energy gaps of the superlattices diminish and even disappear in contrast to its first two counterparts, where the discrepancy between the strained stripe on the left side and pristine stripe on the right side increases the inhomogeneity, and thus the energy gaps.

[en] Highlights: • Four alkaline earth metal MOFs were constructed by a tetracarboxylic acid ligand. • The ligand shows versatile coordination modes and leads to various topologies. • The MOFs reveal selective fluorescent sensors for specific heavy metal ions. -- Abstract: A series of new alkaline earth-metal organic frameworks (AE-MOFs), i.e. {[Mg₂(μ₆-L)(μ₂-OH₂)(H₂O)₄]·DMF}_n (1), [Ca₂(μ₁₀-L)(EtOH)]_n (2), [Sr(μ₆-H₂L)(MeOH)]_n (3) and {[Ba_1.5(μ₅-H₂L)(μ₄-H₃L)(H₂O)₃]·2(H₂O)}_n(4) were synthesized under solvothermal reaction by employing a symmetrical V-shaped multicarboxylic acid ligand H₄L (H₄L = 5,5′-oxydiisophthalic acid), resulting in versatile coordination modes as well as various topologies. 1 forms a uninodal 4-connected (6⁶)-dia 3D topology based on dinuclear Mg₂(COO)₂(μ₂-OH₂) clusters. 2 displays an unprecedented 3-nodal (5,5,10)-connected 3D net with (4²⁴·6²¹)(4⁸·6²)₂ topology based on 1D [Ca(COO)]_n chains and dinuclear Ca₂(COO)₂ clusters. 3 indicates a uninodal 6-connected 3D net with (4¹⁰·6⁵)-sma topology based on 1D [Sr(COO)]_n chains. 4 features a new 4-nodal (4,5,6,6)-connected net with (4³·6³)₂(4⁶·6⁴)₂(4⁶·6⁸·8)(4⁶·6⁹)₂ topology based on two types of 1D chains. 1-4 show solid-state fluorescent properties at ambient temperature. Especially, 1 and 2 have multiresponsive recognition of Fe³⁺ and Pb²⁺ ions, Fe³⁺ and Cu²⁺ ions, respectively, while 3 and 4 show single selective detection for Fe³⁺ ion, signifying that they could be potential fluorescent sensors for specific heavy metal ions in water system. The sensing mechanism has also been discussed in detail.