Xin-Yi Cao

Organically templated metal–organic framework with 2-fold interpenetrated {33.59.63}-lcy net

A new organic cation templated Zn(II) complex (Et3NH)[Zn4(ip)3(bta)3] (, ip = isophthalate, Hbta = benzotriazole) which consists of plate-like Zn4(bta)3 units bridged by ip ligands is reported; it is the first example of a 6-connected uninodal {3(3).5(9).6(3)}-lcy net which has never been observed previously in MOFs but has been theoretically anticipated.

Scorpion-shaped carboxylate ligand tailored molecular square, bilayer, self-threading and (3,6)-connected nets

A novel designed scorpion-shaped 5-oxyacetateisophthalic acid (H3OABDC) was used to construct a series of luminescent metal–organic frameworks, namely [Zn2(HOABDC)2(phen)2(H2O)2]n·nH2O (1), [Zn2(OABDC)(4,4′-bipy)(μ2-OH)(H2O)]n·4/3nH2O (2), [Cd3(OABDC)2(4,4′-bipy)4(H2O)4]n·2nH2O (3), [Cd2(OABDC)(phen)2(μ3-OH)]n·1/3nH2O (4), and [Zn8(OABDC)4(2,2′-bipy)4(μ2-OH)4]n·2nH2O (5) (bipy = bipyridine, phen = 1,10-phenanthroline). Complex 1 features a discrete molecular square and π–π and C–H⋯π interactions between molecular squares give rise to a 2D sheet. Complex 2 shows an unusual 2D bilayer architecture with (3,5)-connected topology. A prominent structural feature in 3 is the self-threading 2D layered structure. Both 4 and 5 exhibit (3,6)-connected topology. In 4, an extraordinary folded four-step-ladder Cd4(OH)2 unit acts as 6-connected node and the framework is 2D (3,6)-connected net. While in 5, the Zn2(OH) unit adopts octahedral geometry and the whole framework features a 3D (3,6)-connected rutile (rtl) topology. Photoluminescence studies revealed that these complexes are interesting blue, green and orange luminescent materials. The thermal stabilities of these complexes are also discussed.

Unusual parallel entanglement of metal–organic 2D frameworks with coexistence of polyrotaxane, polycatenane and interdigitation

Three novel luminescent metal–organic frameworks [Zn(1,2-BBOMB)(4,4′-bipy)1/2]n (1), [Zn2(1,3-BBOMB)2(4,4′-bipy)]n (2) and [Zn4(1,2-BBOMB)4(bpp)2]n (3) have been synthesized by combining the conformationally flexible V-shaped long multicarboxylate ligands and the rigid 4,4′-bipy or flexible bpp ligands with zinc ions under hydrothermal conditions. It is worth mentioning that the layers observed in the three compounds can be reduced to the same 6-connected topological net with (22·48·65) symbol. These complexes display a structural evolution from a two-dimensional (2D) polyrotaxane and polycatenane framework to a three-dimensional (3D) architecture with coexistence of polyrotaxane, polycatenane and interdigitation. The three species contain loops and rods that are interlaced in a highly rare parallel fashion, but with twofold (2D → 2D), triply (2D → 2D) and triply (2D → 3D) entangled features in complexes 1, 2 and 3, respectively. Furthermore, the rotaxane-like interactions between the loops and the rods exhibit a progressive change from one loop interacting with a single rod, to one loop interacting with two identical rods, to finally one loop interacting with two conformationally different rods in complexes 1, 2 and 3, respectively. Photoluminescence studies revealed that these complexes are potential violet, blue and green luminescent materials. The thermal stabilities of these complexes were also discussed.

Single- or double-stranded helices-sustained molecular bilayer architecture

Although pillared layered structures are well-known, helices sustained bilayer motif has not been reported to date. Two metal–organic frameworks [Zn2(OABDC)(OH)]n (1; OABDC = 5-oxyacetateisophthalate) and [Cd3(OABDC)2(bpp)2]n·2nH2O (2; bpp = 1,3-bis(4-pyridyl)propane), have been synthesized on the basis of the assembly of a scorpion-shaped carboxylate and auxiliary pyridine-based ligands with d10 metal ions under hydrothermal conditions. Complex 1 demonstrates an interesting 3D MOF, which is alternately assembled by 2D metal–organic bilayers and 1D inorganic cylindrical 21 helices along the b axis. Complex 2 gives a novel example of 3D MOF comprised of the intra-bilayer and double-stranded helices of interlayer mutual racemization. Photoluminescence studies revealed that both complexes are potentially blue luminescent materials. The thermal stabilities of these complexes were also discussed.

Co-chelation of a scorpion-shaped carboxylate ligand and phenanthroline lead to a 2-D interpenetratively tubular architecture

A novel zinc coordination supramolecular complex, {[Zn3(OABDC)2(phen)3]·2H2O}n, with an open-ended nanotube architecture based on a nano-sized tetranuclear Zn4(OABDC)4 metallacycle repeating unit, is strategically designed and synthesized using a unique scorpion-shaped carboxylate ligand (5-oxyacetate isophthalic acid = H3OABDC) and phenanthroline.

Canted antiferromagnetic behaviours in isostructural Co(II) and Ni(II) frameworks with helical lvt topology

The hydrothermal reaction of the versatile ligand 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (Hmtpo), and cobalt/nickel acetate afforded two isostructural Co(II) and Ni(II) frameworks [M(mtpo)2(H2O)]n (M = Co (1Co) or Ni (2Ni)). Both of them consist of heterochiral helical meshes fused together into a non-interpenetrated lvt topological network containing only planar four-coordinate nodes. The frameworks can be rationalized to a rare 6-c crs net if the water-donated hydrogen-bonds are considered. Two isomorphous complexes exhibit spin-canted antiferromagnetism, with the critical temperature Tc of ca. 3.0 K for 1Co and 19 K for 2Ni. The additional magnetic measurements (after the removal of guest molecules), IR, TGA and XRPD of the complexes were also discussed.

Trapping in situ scission products of C–O ester bonds by unique coordination supramolecular architectures

Various decomposition products of C–O ether bond cleavage have been trapped in supramolecular architectures as templates based on hydrothermal reaction of three-component metal–carboxylate–phen, which not only results in the formation of [5]pseudorotaxane structure, 3D porous framework and supramolecular structure, but also provides directly crystallographic evidence to explain how the C–O ether bond breaks during decomposition.

Poly[[[(1,10-phenanthroline-κ2N, N')-zinc(II)]-μ3-5-hydroxyisophthalato-κ4O, O' :O'':O'''] monohydrate]

In the title compound, [[Zn(C8H4O5)(C12H8N2)].H2O]n or [[Zn(OH-BDC)(phen)].H2O]n (where OH-H2BDC is 5-hydroxyisophthalic acid and phen is 1,10-phenanthroline), the Zn atoms are coordinated by two N atoms from the phen ligands and by four O atoms from hydroxyisophthalate ligands in a highly distorted octahedral geometry, with Zn-O distances in the range 2.042 (4)-2.085 (5) A and Zn-N distances of 2.133 (5) and 2.137 (5) A. The [[Zn(OH-BDC)(phen)].H2O]n infinite zigzag polymer forms a helical chain of [Zn2(OH-BDC)2]n units. Face-to-face pi-pi interactions (3.60-3.75 A) occur between two phen rings belonging to the same helical chain. Consolidation of the packing structure is achieved by O-H...O hydrogen-bonding interactions between the carboxylate O atoms, the hydroxyl group and the water molecule, forming two-dimensional sheets.

Poly­[[[(1,10-phenanthroline-κ2N,N′)­zinc(II)]-μ3-5-hydroxy­isophthalato-κ4O,O′:O′′:O′′′] monohydrate]

In the title compound, [[Zn(C8H4O5)(C12H8N2)].H2O]n or [[Zn(OH-BDC)(phen)].H2O]n (where OH-H2BDC is 5-hydroxyisophthalic acid and phen is 1,10-phenanthroline), the Zn atoms are coordinated by two N atoms from the phen ligands and by four O atoms from hydroxyisophthalate ligands in a highly distorted octahedral geometry, with Zn-O distances in the range 2.042 (4)-2.085 (5) A and Zn-N distances of 2.133 (5) and 2.137 (5) A. The [[Zn(OH-BDC)(phen)].H2O]n infinite zigzag polymer forms a helical chain of [Zn2(OH-BDC)2]n units. Face-to-face pi-pi interactions (3.60-3.75 A) occur between two phen rings belonging to the same helical chain. Consolidation of the packing structure is achieved by O-H...O hydrogen-bonding interactions between the carboxylate O atoms, the hydroxyl group and the water molecule, forming two-dimensional sheets.

Poly[[[(1,10-phenanthroline-kappa2N,N')zinc(II)]-mu3-5-hydroxyisophthalato-kappa4O,O':O":O"'] monohydrate].

In the title compound, [[Zn(C8H4O5)(C12H8N2)].H2O]n or [[Zn(OH-BDC)(phen)].H2O]n (where OH-H2BDC is 5-hydroxyisophthalic acid and phen is 1,10-phenanthroline), the Zn atoms are coordinated by two N atoms from the phen ligands and by four O atoms from hydroxyisophthalate ligands in a highly distorted octahedral geometry, with Zn-O distances in the range 2.042 (4)-2.085 (5) A and Zn-N distances of 2.133 (5) and 2.137 (5) A. The [[Zn(OH-BDC)(phen)].H2O]n infinite zigzag polymer forms a helical chain of [Zn2(OH-BDC)2]n units. Face-to-face pi-pi interactions (3.60-3.75 A) occur between two phen rings belonging to the same helical chain. Consolidation of the packing structure is achieved by O-H...O hydrogen-bonding interactions between the carboxylate O atoms, the hydroxyl group and the water molecule, forming two-dimensional sheets.