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Heterometallic cluster-organic frameworks with fascinating architectures and multi-functionality have the potential to be applied in various fields. However, in comparison with p–d, d–d, and d–f heterometallic cluster-organic frameworks, p–f heterometallic cluster-organic frameworks are far less explored even though they possess multiple merits. Herein, two novel isomorphic 4p–4f heterometallic cluster-organic frameworks based on high-nuclear [Ln11Ge12] (Ln = Pr, L1 and Nd, L2) second building units have been successfully synthesized via a hydrothermal approach by using bis(carboxyethylgermanium) sesquioxide (H2E2Ge2O3, E = –CH2CH2COO–). The [Ln11Ge12] cluster is constructed with two Ln-capped Ge6-rings sandwiching a gear-like [Ln9] unit. The as-prepared 4p–4f heterometallic [Ln11Ge12] cluster-organic frameworks possess two-dimensional (2D) layered structures. Moreover, the property study reveals the selective and sensitive luminescence sensing of Fe3+ with L1, exhibiting its promising application in environmental monitoring.

Six novel heterobimetallic cyanide-bridged complexes formulated as {[Cu(dmpn)2]2[Fe(bpb)(CN)2]}[Fe(bpb)(CN)2](ClO4)2·2H2O (1), [Cu(dmpn)2][Fe(bbp)(CN)3]n·0.5nDMF·2.5nH2O (2), {[Cu(dmpn)2]1.5[Cr(CN)5(NO)]}n·3nH2O (3), {[Cu(dmpn)2]2[Fe(CN)6]}n·10nH2O (4), {[Cu(dmpn)2]4[Mo(CN)8]2}·CH3CN·2H2O (5), and {[Cu(dmpn)2]4[W(CN)8]2}·CH3CN·2H2O (6) (bpb = 1,2-bis(pyridine-2-carboxamido)benzenate, bbp = 2,6-bis(benzimidazoi-2-yl)pyridine, dmpn = 2,2-dimethyl-1,3-diaminopropane, DMF = N,N-dimethylformamide) were synthesized with one amine copper compound as an assembly segment and six polycyanometallates containing two, three, five, six or eight cyanide groups as building blocks. All of the six complexes have been characterized using elemental analysis, IR spectra, and powder and single crystal X-ray diffraction. Structural analysis revealed diverse structural types of complexes 1–6, ranging from discrete polynuclear entities (1) to a 1D single chain (2) to 2D (3, 5 and 6) and 3D (4) networks, clearly indicating the important role of the building block in tuning the structures of the target complexes. The magnetic properties of the reported cyanide-bridged complexes have been experimentally studied and theoretically simulated, disclosing ferro- or antiferromagnetic coupling between the low spin Fe(III) ion and Cu(II) ion and the antiferromagnetic interaction between the Cr(I) ion and the Cu(II) ion through the cyanide bridge. Furthermore, the nature of the magnetic coupling has been analysed based on the magneto-structural correlation.

Assembled from a reduced Schiff base tricarboxylate ligand H3L, two novel Cd-MOFs with the formulae {[Cd(HL)(bpy)]·1.25H2O·1.5DMF}n (LCU-107) and {[Cd(HL)(bpea)·H2O]·H2O·DMF}n (LCU-108) (where LCU stands for Liaocheng University, H3L = 5-(4-carboxybenzylamino)isophthalic acid, bpy = 4,4′-bipyridine, and bpea = 1,2-di(4-pyridyl)ethane), were obtained. LCU-107 possesses a 3D pcu framework based on dinuclear units. LCU-108 demonstrates an interesting 2D → 2D interdigitating and penetrating structure. The flexible carboxylate ligands can all bend in these complexes due to the rotation of –CH2–NH– groups. Luminescence measurements indicated that these two Cd-MOFs show highly selective and sensitive sensing activities toward acetylacetone (acac) and Cr2O72− through a luminescence enhancement and a quenching effect, respectively. The detection limits toward acac are as low as 0.136 and 0.058 ppm, respectively. To our knowledge, these two Cd-MOFs may represent very rare examples of special turn-on acac sensors, as well as being dual-responsive chemosensors for both acac and Cr2O72−.

Two Cd(II) coordination polymers (CPs) were assembled from the mixed ligand strategy of π-conjugated aromatic polycarboxylates and bis(imidazole) linkers, with the structures being a 2-fold interpenetrating 3D bbf net for 1 and a 2D hxl sheet for 2. The fluorescence measurements revealed that both Cd(II) CPs were promising luminescent sensors for the detection of nitrofuran/nitroimidazole antibiotics (ABXs) with low detection limits. Besides, the luminescence quenching of the two Cd(II) CPs toward ABXs was investigated by using DFT calculations and spectral overlap experiments.

Two isostructural (3,6)-connected porous coordination polymers topologically featuring both self- and interpenetration have been successfully synthesized. The porous material shows a reversible crystalline-to-amorphous transition associated with the removal and recapture of guest molecules. Particularly, the porous material demonstrates selective detection of nitrobenzene through fluorescence quenching.

A Cd(II)-based metal–organic framework, {[Cd2L(H2O)2]·DMF·H2O}n (1), has been successfully constructed from a new flexible antler-like multidentate ditopic ligand (H4L). This metal–organic framework shows highly sensitive fluorescence sensing of nitrobenzene.

Eight mixed-ligand coordination compounds, [Zn(PA)(bpp)]n (1), {[Cd(PA)2(Hbpp)2(H2O)2]·2H2O}n (2), [Zn(PA)(bbi)]n (3), [Cd(PA)(bbi)(H2O)]n (4), {[Cd3(PA)2(bbi)3(Cl)2]}n (5), {[Zn6(PA)5(datrz)2(Hdatrz)2(H2O)2]·16DMF}n (6), [Cd2(PA)(datrz)2(DMF)2]n (7), and {[Cd2(PA)2(bix)2(DMF)2]·4DMF}n (8) (bpp = 1,3-bi(4-pyridyl)propane, bbi = 1,4-bis(imidazol-1-yl)butane, H2datrz = 3,5-diamino-1,2,4-triazole, bix = 1,4-bis(imidazol-1-ylmethyl)benzene), have been synthesized through the reaction of zinc and cadmium salts with pamoic acid (H2PA) and different N-donor ligands. The assembly of the ligands in different coordination modes and conformations leads to fascinating structures. 1 and 3 afford an interpenetrating polythreaded 2D → 3D motif composed of 44 sql undulated sheets, while right- and left-helices are alternatively arranged in 3. 2 possesses an interesting 3-D supramolecular network with 1-D hydrogen-bonded chains spanning different directions. 4 and 5 display both polyrotaxane and polycatenane characteristics. In 4, two 2,4-connected (4·85) nets interlocked with each other, forming a 2D → 2D polycatenating network. 5 exhibits a twofold interpenetrated (3,5,6)-connected (3·5·6)(3·52·67)(32·54·66·72·9) topology. 6 and 7 represent rare pentanodal (3,4)-connected and binodal (3,4)-connected frameworks with topologies of (4·5·6)(4·8·10)(52·6·8·9·11)(4·5·6·8·92)(4·5·7) and (4·6·8)(4·62·83), respectively. 8 displays 3-fold interpenetrated 4-connected SrAl2 topology with flexible bix ligands bridging Cd centers to form right- and left-helices. The mixed-ligand effect of the conformations of the PA ligand and N-heterocyclic coligands as well as the metal centers on the assembly of frameworks is unravelled in detail. Solid-state luminescence properties of all compounds were reported as well. Moreover, fluorescence properties of compounds 6 and 8 in various solvent suspensions at room temperature have also been investigated.

Two genuine supramolecular isomers of Cd(II) coordination polymers with an identical formula of [Cd(pptp)(ox)]n (1a and 1b) (pptp = 2-(3-(4-(pyridin-4-yl)phenyl)-1H-1,2,4-triazol-5-yl)pyridine, H2ox = oxalic acid) have been hydrothermally synthesized and characterized. Both compounds possess the rod-like binuclear [Cd2(pptp)2] subunit, which are linked by the ox ligand to afford either a flat or wavy two-dimensional (2D) 63-hcb network, depending upon whether the additive agent is used for the reaction. The photoluminescence behaviour of the compounds was also discussed.

Five coordination polymers with four different typological structures have been obtained based on 2,3,5,6-tetramethyl-1,4-benzenedicarboxylate acid (H2TBDC) and bipyridine ligands: 1D zigzag chain Cd(2,2′-bpy)(TBDC)(H2O)·H2O (1), 2D grid with (4,4)-net Co(H2O)2(4,4′-bpy)(TBDC)·2H2O (2), 3D interpenetrating frameworks with diamond topology Ni(4,4′-bpy)(TBDC) (3) and Cu(4,4′-bpy)(TBDC) (4), 3D porous framework with pcu network Co2(4,4′-bpy)(TBDC)2·2H2O·5DMF (5). Especially, complexes 2 and 5 with different topologies were obtained by use of the same reactant but change of the solvents. The gas sorption of complex 5 has also been studied.

Solvothermal reactions of aromatic quaterphenyl-2,5,2′,5′-tetracarboxylic acid (H4qptc) ligand and transitional metal cations of MII (M = Co, Ni, Mn, Cu, Zn) in the presence of 1,10-phenanthroline (phen) afford five new coordination polymers (CPs), namely, {[M(H2qptc)(phen)(H2O)2]·2H2O}n (M = Co (1), Ni (2)), [Mn(qptc)0.5(phen)(H2O)]n (3), [Cu(qptc)0.5(phen)]n (4) and [Zn3(Hqptc)2(phen)2(H2O)2]n (5). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Complexes 1 and 2 are isostructures and each displays a one-dimensional (1D) zigzag chain, which further forms a 2D supramolecular architecture via inter-chain π⋯π interactions. Complex 3 possesses a (3,6)-connected CdI2 layered architecture incorporating left- and right-handed helical chains. Complex 4 exhibits a 3D porous structure with rare (3,6)-connected ant topology. Complex 5 shows a 3D (3,4,5)-connected network with (42.6)2(43.62.8)(45.64.8)2 topology. The results show that the conformations and coordination modes of H2qptc2−/qptc4− ligand are crucial factors for the formation of the different structures. Moreover, the photoluminescence of 5 has been investigated.

Three supramolecular isomeric metal–organic frameworks (MOFs) have been synthesized at different temperatures, exhibiting a structural progression from 2D (4,4) layer structures (α and β) to a 3D acentric 3-fold diamondoid network (γ).