Two new coordination polymers, Cu(Hbsal)2(4,4′-bpy)2 (1) and Cu(bsal)(4,4′-bpy)·DMF (2), have been synthesized from 5-bromosalicylic acid (H2bsal) and the auxiliary ligand 4,4′-bipyridine (4,4′-bpy) through a slow diffusion method. Compound 1 is composed of parallel 1D linear chains, whereas compound 2 represents a non-interpenetrated 3D sod net which is constructed from left and right-handed helical chains alternately separated by 4,4′-bpy. The most interesting finding is that compound 1 can be irreversibly transformed into 2 in a crystal-to-crystal manner in the case that compound 1 is immersed in the DMF solvent. Particularly, the 1D-to-3D crystal-to-crystal structural transformation also incurs a drastic change in the magnetic properties of 1 and 2.

The reaction of Cd(NO3)2·4H2O and 4-carboxy-1-(4-carboxybenzyl)pyridinium bromide (H2LBr) under different reaction conditions generates two pseudopolymorphs, {[Cd(L)2]·2H2O}⊃C3H6O (1α) and {[Cd(L)2]·2H2O}⊃3H2O (1β). Crystal structure analysis reveals that complexes 1α and 1β feature an essentially identical 1D metallacyclic chain structure, and their structural differences mainly stem from different packing modes of the identical 2D sheets, consisting of identical 1D metallacyclic chains linked via π⋯π interactions. Corresponding to the different packing modes, complexes 1α and 1β have distinctly different space groups: the acentric orthorhombic space group Fdd2 for 1α and the centric monoclinic space group I2/c for 1β. For acentric 1α crystals, modest powder second-harmonic-generation (SHG) efficiency is observed at room temperature.

Three Cd(II)-based coordination polymers 1–3 with unique structures and topologies have been successfully constructed under solvothermal conditions by use of a newly designed N-containing rigid triangular ligand tris(4-(4H-1,2,4-triazol-4-yl)phenyl)amine (TTPA-4), wherein the structural interpenetration can be modulated by aromatic dicarboxylate coligands including thiophene-2,5-dicarboxylic acid (TDA) and terephthalic acid (TPA). Without using coligands, a noninterpenetrating porous 3-D network of 1 with nia topology was obtained. With the aid of the V-shaped TDA coligand, a 4-fold interpenetrating 3-D network of 2 resulted that is built from (2,3,7)-connecting (42.6)(44.6.88.104.124)(4)2 net. In the presence of the linear TPA auxiliary ligand, an 8-fold interpenetrating 3-D network of 3 was produced that is assembled by 3-connecting uninodal srs net. Particularly, compound 1 displays interesting dual function as the result of its unique structural attributes, which not only shows superb sensitivity for nitroaromatics (NACs) with phenolic group but also impressive removal capabilities of toxic Cr2O72– oxoanion pollutant from aqueous solution.

An anionic zeolite-like metal–organic framework (AZMOF) with a twisted partially augmented the net, known as the “Moravia” net, [(CH3)2NH2]6[Sr13(O)3(BTTC)8(OH)2(H2O)16]·xS (Sr-BTTC, where S represents non-coordinated solvent molecules, and BTTC is the abbreviation of benzo-(1,2;3,4;5,6)-tris-(thiophene-2′-carboxylic acid)), has been solvothermally synthesized and characterized, which possesses an anionic framework and nano-sized sodalite cage. Through cation-exchange, Sr-BTTC is capable of uptaking large organic cationic dyes including Rhodamine B (RB), Basic Red 2 (BR2), Crystal Violet (CV) and Methylene Blue (MB), amongst which the adsorption capability for RB (up to 545 mg g−1), and BR2 (up to 675 mg g−1) is the highest for reported absorbants to date.

Six Zn(II) coordination polymers, [Zn(H2L)(Hipa-CH3)2]·2H2O (1), [Zn2(HL)2(ipa-CH3)] (2), [Zn2(HL)2(ipa-NO2)]·2H2O (3), [Zn2(HL)2(ipa-NO2)] (4), [Zn2(HL)(BTCA)(H2O)]·H2O (5), and [Zn3(HL)3(BTCA)] (6), were synthesized by reactions of Zn(II) salts with rigid ligand 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (H2L) and different carboxylic acids, 5-methyl-isophthalic acid (H2ipa-CH3), 5-nitro-isophthalic acid (H2ipa-NO2), and 1,2,4-benzenetricarboxylic acid (H3BTCA). Complexes 1 and 2 were formed under different pH values, and 1 is a one-dimensional (1D) chain extended by hydrogen bonds and π–π stacking interactions to form a three-dimensional (3D) supramolecular polymer, while 2 exhibits a uninodal 6-connected 3D architecture with (412·63)-pcu topology based on the binuclear Zn(II) secondary building units (SBUs). Polymers 3 and 4 present a pair of pseudopolymorphs with layered-pillared framework. Polymer 3 possesses Zn2(HL–)22+ sheets pillared by the ipa-NO22– ligand to form a 3D net, while 4 builds on the [Zn2(HL)(ipa-NO2)]+ layer pillared by HL– ligand. Complex 5 is a (3,8)-connected tfz-d 3D net with point (Schläfli) symbol (43)2(46·618·84) based on the tetranuclear [Zn4(COO)4] SBUs, while the BTCA3– ligands act as three-connector pillars to link adjacent [Zn3(HL–)3]3– layers into a 3D net for 6. Complexes 1–6 exhibit intense light blue emission in the solid state at room temperature, and activated sample 6 shows highly selective CO2 uptake over N2 and H2.

Solvothermal reaction of a TCA (TCA = 4,4′,4′′-tricarboxytriphenylamine) ligand with Cd(NO3)2 yielded a unique 3D 12-connected metal–organic framework of 1, which can be simplified as a (3,3,12)-connected 3-nodal net with a Schläfli symbol of {416·636·814}{42·6}2{43}2 based on a 12-connected node of a pentanuclear Cd(II) cluster and a three-connected organic linker of TCA. Compound 1 exhibits both photoluminescence and proton conductivity. The luminescence properties of 1 originate from the triphenylamine chromophore of the TCA ligand. The proton conductivity of 1 is supposed to be relevant to the structure attributes of 1. On the one hand, the curved narrow channels lined with a hydrophilic pentanuclear Cd(II) cluster in 1 can improve the water affinity of framework and facilitate the water absorption under humid conditions. On the other hand, the coordinated water molecules within the pentanuclear Cd(II) cluster can produce a mobile H+ proton due to coordination activation. At 80 °C and 85% RH (relative humidity), compound 1 shows the proton conductivity of 1.45 × 10−6 S cm−1.

Solvothermal reaction of the H3BTTC (benzo-(1,2;3,4;5,6)-tris(thiophene-2′-carboxylic acid)) ligand with Pb(NO3)2 produced a unique 3-D polycatenated architecture that was constructed by octuple intercatenation of discrete icosahedral coordination cages.

The first two families of homodinuclear lanthanide(III) complexes, formulated as [(LOEt)2Ln2(L1)] and [(LOEt)2Ln2(L2)] (Ln3+ = Dy3+, Tb3+, Ho3+, Gd3+, and Y3+; L14− = 2,2′,2′′,2′′′-[1,2,4,5-benzenetetrayltetrakis(nitrilomethylidyne)]tetrakisphenolate; L24− = 2,2′,2′′,2′′′-[[1,1′-biphenyl]-3,3′,4,4′-tetrayltetrakis(nitrilomethylidyne)]tetrakis(4-chlorophenolate); LOEt− = (η5-cyclopentadienyl)tris(diethylphosphito-p)cobaltate(III)), were successfully synthesized based on Kläui's tripodal building block NaLOEt and two dinucleating Schiff base ligands, H4L1 and H4L2, respectively. Single-crystal X-ray analyses show that these lanthanide complexes have two seven-coordinated metal binding sites, linked to each other with a phenyl or biphenyl bridge. Variable temperature dc magnetic measurements reveal the weakly antiferromagnetic coupling between paramagnetic lanthanide ions, while ac magnetic data exhibit the field-induced relaxation of magnetization for the corresponding Dy2 complexes 1 and 6. A further magnetic dilution study for 1 suggests that the slow magnetic relaxation originates from the single-ion magnetic behaviour of Dy3+ ions.

Reactions of metal ions with a rigid linear ligand 4-H2IBA incorporating 4-imidazolyl and carboxylate functional groups [4-H2IBA = 4-(1H-imidazol-4-yl)benzoic acid] under variable reaction conditions gave 11 new coordination polymers, [Cu(4-HIBA)2(H2O)4] (1), [CuIICuI(4-HIBA)(4-IBA)(H2O)2]·2.3H2O (2), [Cu(4-HIBA)(Cl)] (3), [Cu3(4-HIBA)6]·7.8H2O (4), [Cd(4-HIBA)2(H2O)]·2H2O (5), [Cd(4-HIBA)2] (6), [Cd(4-HIBA)2]·2DMF (7), [Cd2(4-HIBA)4]·H2O (8), [Zn(4-HIBA)2]·H2O (9), [Zn(4-HIBA)2]·C2H5OH·DMF (10), and [Co(4-HIBA)2]·2DMF (11). The copper complexes 1–4 are discrete molecules to three-dimensional (3D) infinite networks. Complexes 1 and 2 formed in different reaction temperatures exhibit a mononuclear motif and one-dimensional (1D) chain, respectively. Compounds 3 and 4 were obtained through controlling reaction solvent systems, and 3 features a two-dimensional (2D) (4,4) network by taking the binuclear [Cu2(Cl)2] as 4-connecting nodes, whereas 4 is a 3-fold interpenetrating mog net with Point (Schläfli) symbol of (4·64·8)2(42·62·82). The 4-HIBA– ligands act as rod-type two-connectors to connect metal Cd(II) centers into 4-connected 3D frameworks with different topologies: binodal 4-connected network with a Point (Schläfli) symbol of (86) (5) and uninodal (65·8) net (6), uninodal 4-connected [2 + 2] interpenetrating (66) dia net (7), and 5-fold interpenetrating dia net (8), respectively. Complex 9 has a 1D double chain structure, while 10 and 11 are isostructural as 7. Fluorescence and gas adsorption properties of the compounds have also been explored.

By the combination of different metal salts and solvents, four unprecedented in situ reactions have been discovered for heterocyclic disulfide of 2-ppds (2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide). In the CH3CN–DMF solvent, reaction of 2-ppds with AgNO3 produced a one-dimensional chain structure of {[Ag2(1L)2]·2CH3CN}n (1), wherein 2-ppds was converted into its sulfonate of 1L by means of oxidative cleavage of the S–S bond. In the CH3CN–DCM solvent, reaction between 2-ppds and Cu(ClO4)2 yielded a discrete mononuclear Cu(II) coordination structure of [Cu(2L)2H2O)](ClO4)2 (2), of which 2-ppds was turned into a totally unexpected zwitterion product of 2Lvia C–S bond scission followed by O substitution. In the MeOH–DCM solvent, reaction of 2-ppds with Co(ClO4)2 resulted in a mononuclear Co(III) coordination structure of [Co(3L)2]ClO4·2CH3OH·H2O (3), in which 2-ppds was transformed into its persulfide of 3Lvia selective single C–S bond rupture. In the CH3CN–DMF solvent, reaction between 2-ppds and CuI afforded a binuclear mixed-valence CuICuII coordination structure of [Cu2I(4L)2] (4), wherein 2-ppds was converted into its thiolate of 4L through homolytic S–S bond cleavage. The reaction mechanisms of these reactions have also been discussed on the basis of these in situ generated coordination structures coupled with our previous observations on 2-ppds.

Six new coordination polymers [Cd2(HL)2(pbda)(H2O)2]·4H2O (1), [Cd2(HL)2(mbda)(H2O)2]·6H2O (2), [Cd(H2L)(mmbda)(H2O)] (3), [Cd2(H2L)2(btca) (H2O)2]·4H2O (4), [Zn2(H2L)2(btca)] (5) and [Zn6(H2L)6(btca)3] (6) were synthesized by reactions of cadmium(II)/zinc(II) salts with a rigid ligand 1-(1H-imidazol-4-yl)-3-(4H-tetrazol-5-yl)benzene (H2L) and different carboxylic acids of 1,4-benzenedicarboxylic acid (H2pbda), 1,3-benzenedicarboxylic acid (H2mbda), 5-methyl-1,3-benzenedicarboxylic acid (H2mmbda), 1,2,4,5-benzenetetracarboxylic acid (H4btca), respectively. The structures of the complexes were determined by single crystal X-ray diffraction analysis. Although complexes 1 and 2 possess the same two-dimensional (2D) network with (4·82)-fes topology built from Cd(II)–(HL)− moieties, different coordinated orientation of auxiliary carboxylates of pbda2− and mbda2− pillar the 2D layer into distinct frameworks. Complex 1 is an unusual binodal (3,4)-connected three-dimensional (3D) dmc net with Point (Schläfli) symbol of (4·82)(4·85) while 2 is a rare binodal (3,4)-connected 3D architecture with a (4·6·8)(4·62·83) fsc-3,4-C2/c topology. Complexes 3 and 4 have the same 2D networks with (4,4) topology, and H-bonding or π–π stacking interactions extending the 2D layers into 3D supramolecular frameworks, respectively. Complexes 5 and 6 present a pair of pseudopolymorphs, and 5 is an uninodal (4,4)-connected 3D net with Point (Schläfli) symbol of (62·84)(64·82)2 while 6 is an unprecedented penta-nodal 4-connected net with (4·62·83)2(4·64·8)2(62·84)(64·82)4 topology. The thermal stability and photoluminescent property of the complexes were investigated.

The first two families of homodinuclear lanthanide(III) complexes, formulated as [(LOEt)2Ln2(L1)] and [(LOEt)2Ln2(L2)] (Ln3+ = Dy3+, Tb3+, Ho3+, Gd3+, and Y3+; L14− = 2,2′,2′′,2′′′-[1,2,4,5-benzenetetrayltetrakis(nitrilomethylidyne)]tetrakisphenolate; L24− = 2,2′,2′′,2′′′-[[1,1′-biphenyl]-3,3′,4,4′-tetrayltetrakis(nitrilomethylidyne)]tetrakis(4-chlorophenolate); LOEt− = (η5-cyclopentadienyl)tris(diethylphosphito-p)cobaltate(III)), were successfully synthesized based on Kläui's tripodal building block NaLOEt and two dinucleating Schiff base ligands, H4L1 and H4L2, respectively. Single-crystal X-ray analyses show that these lanthanide complexes have two seven-coordinated metal binding sites, linked to each other with a phenyl or biphenyl bridge. Variable temperature dc magnetic measurements reveal the weakly antiferromagnetic coupling between paramagnetic lanthanide ions, while ac magnetic data exhibit the field-induced relaxation of magnetization for the corresponding Dy2 complexes 1 and 6. A further magnetic dilution study for 1 suggests that the slow magnetic relaxation originates from the single-ion magnetic behaviour of Dy3+ ions.

By the combination of different metal salts and solvents, four unprecedented in situ reactions have been discovered for heterocyclic disulfide of 2-ppds (2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide). In the CH3CN–DMF solvent, reaction of 2-ppds with AgNO3 produced a one-dimensional chain structure of {[Ag2(1L)2]·2CH3CN}n (1), wherein 2-ppds was converted into its sulfonate of 1L by means of oxidative cleavage of the S–S bond. In the CH3CN–DCM solvent, reaction between 2-ppds and Cu(ClO4)2 yielded a discrete mononuclear Cu(II) coordination structure of [Cu(2L)2H2O)](ClO4)2 (2), of which 2-ppds was turned into a totally unexpected zwitterion product of 2Lvia C–S bond scission followed by O substitution. In the MeOH–DCM solvent, reaction of 2-ppds with Co(ClO4)2 resulted in a mononuclear Co(III) coordination structure of [Co(3L)2]ClO4·2CH3OH·H2O (3), in which 2-ppds was transformed into its persulfide of 3Lvia selective single C–S bond rupture. In the CH3CN–DMF solvent, reaction between 2-ppds and CuI afforded a binuclear mixed-valence CuICuII coordination structure of [Cu2I(4L)2] (4), wherein 2-ppds was converted into its thiolate of 4L through homolytic S–S bond cleavage. The reaction mechanisms of these reactions have also been discussed on the basis of these in situ generated coordination structures coupled with our previous observations on 2-ppds.

Solvothermal reaction of a TCA (TCA = 4,4′,4′′-tricarboxytriphenylamine) ligand with Cd(NO3)2 yielded a unique 3D 12-connected metal–organic framework of 1, which can be simplified as a (3,3,12)-connected 3-nodal net with a Schläfli symbol of {416·636·814}{42·6}2{43}2 based on a 12-connected node of a pentanuclear Cd(II) cluster and a three-connected organic linker of TCA. Compound 1 exhibits both photoluminescence and proton conductivity. The luminescence properties of 1 originate from the triphenylamine chromophore of the TCA ligand. The proton conductivity of 1 is supposed to be relevant to the structure attributes of 1. On the one hand, the curved narrow channels lined with a hydrophilic pentanuclear Cd(II) cluster in 1 can improve the water affinity of framework and facilitate the water absorption under humid conditions. On the other hand, the coordinated water molecules within the pentanuclear Cd(II) cluster can produce a mobile H+ proton due to coordination activation. At 80 °C and 85% RH (relative humidity), compound 1 shows the proton conductivity of 1.45 × 10−6 S cm−1.

An anionic zeolite-like metal–organic framework (AZMOF) with a twisted partially augmented the net, known as the “Moravia” net, [(CH3)2NH2]6[Sr13(O)3(BTTC)8(OH)2(H2O)16]·xS (Sr-BTTC, where S represents non-coordinated solvent molecules, and BTTC is the abbreviation of benzo-(1,2;3,4;5,6)-tris-(thiophene-2′-carboxylic acid)), has been solvothermally synthesized and characterized, which possesses an anionic framework and nano-sized sodalite cage. Through cation-exchange, Sr-BTTC is capable of uptaking large organic cationic dyes including Rhodamine B (RB), Basic Red 2 (BR2), Crystal Violet (CV) and Methylene Blue (MB), amongst which the adsorption capability for RB (up to 545 mg g−1), and BR2 (up to 675 mg g−1) is the highest for reported absorbants to date.