Yun-Wu Li

Assembly of a series of d10 coordination polymers of pamoic acid through a mixed-ligand synthetic strategy: syntheses, structures and fluorescence properties

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.

A new Cd(II)-based metal–organic framework for highly sensitive fluorescence sensing of nitrobenzene

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.

Solvent- and metal-directed lanthanide-organic frameworks based on pamoic acid: observation of slow magnetization relaxation, magnetocaloric effect and luminescent sensing

Two types of lanthanide coordination polymers, namely, [Ln(PA)(NO3)(DMA)3]n (Ln=Gd (1), Dy (2), Eu (3), Tb (4)) (type I), and {[Ln2(PA)3(DMF)4]·2DMF} (Ln=Eu (5), Tb (6)) (type II) (PA=Pamoic acid, DMA=dimethylacetamide, DMF=N,N-dimethylformamide), have been synthesized by the reaction of Ln(NO3)3·6H2O with pamoic acid through layer diffusion method. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy (IR), thermogravimetric analysis (TGA), fluorescence and magnetic measurements. Solvents and lanthanide atoms in the reaction play an important role in controlling different structures. Type I demonstrated 1-D linear chain structure connected by Ln atoms and PA ligands. Type II exhibited non-interpenetrating 3-D 6-connected 43612 nets based on binuclear [Ln2(CO2)6(DMF)4] cores. Magnetic properties of complexes 1–4 were investigated in details. Complex 1 shows significant magnetocaloric effect with–ΔSm=20.37 J kg–1 K–1 at 3.0 K and 7 T. Complex 2 exhibits slow relaxation of the magnetization. Complexes 3–6 exhibit both ligand- and metal-centered fluorescent properties. Complex 6 demonstrates fluorescent sensing of DMF and Cu2+ ion.

Coexistence of self- and interpenetration in two (3,6)-connected porous coordination polymers

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.

Self-assembly, structures, magnetic properties and solution behaviors of six mixed-valence cobalt clusters

The introduction of multidentate chelating ligands and secondary small inorganic anions into a variable-valence cobalt synthesis system led to the formation of six novel mixed-valence cobalt clusters, namely, [CoII2CoIII2(mdea)2(OH)2(2,2′-bipy)2(CH3CN)4]·4ClO4·2H2O (SD/Co1), [CoII2CoIII2(dmhmp)6(CH3CN)4]·4ClO4·4CH3CN (SD/Co2), [CoIICoIII4(mdea)4(N3)4(piv)2] (SD/Co3), [CoII2CoIII2Na(mdea)2(N3)(piv)8] (SD/Co4), [CoII4CoIII2(dea)2(Hdea)4(piv)4]·2piv (SD/Co5), and [CoII2CoIII2(mdea)2(dmpea)2(OH)2(CH3CN)2(H2O)2]·4ClO4·2H2O (SD/Co6) (H2dea = diethanolamine, H2mdea = N-methyldiethanolamine, 2,2′-bipy = 2,2′-bipyridine, Hdmhmp = 3,5-dimethyl-1-(hydroxymethyl)-pyrazole, Hpiv = pivalic acid and dmpea = 1-(3,5-dimethyl-1H-pyrazol-1-yl)-ethanimine). Among them, compounds SD/Co1, SD/Co2 and SD/Co6 have a similar cationic tetranuclear core motif {Co4O6} consisting of two CoIII and two CoII mixed-valence ions. Compound SD/Co3 has two similar neutral pentanuclear {Co5O8} clusters co-crystallized in one asymmetric unit that each contains four CoIII ions and one CoII ion. Compound SD/Co4 consists of a bimetallic pentanuclear calyx-like {Co4Na} skeleton including two CoIII and two CoII ions, while compound SD/Co5 has a cationic hexanuclear rod-like cluster {Co6O8} consisting of two CoIII and four CoII ions. In addition, the high-resolution electrospray ionization mass spectrometry (HRESI-MS) technique was introduced to detect their solution behaviors and reveal their evolutional processes. Magnetic measurements indicated that these cobalt clusters show distinct magnetic behaviors at low temperature.

Solution Behavior and Magnetic Property of A Novel Nonanuclear Copper(II) Cluster

A novel nonanuclear copper(II) nanocluster (Cu9) was constructed from a well-designed multidentate pyrazole–alcohol ligand and using various small anions. The Cu9 skeleton was found to consist of two similar Cu5 cluster units sharing one central CuII ion and to be protected by the outer organic ligand and auxiliary small anions. The solution behavior of Cu9 was studied in detail by applying the ESI-MS technique. Magnetism analysis implied the presence of antiferromagnetic interactions between the CuII ions.

A pillar-layered porous CoII-MOF with dual active sites for selective gas adsorption

A pillar-layered microporous MOF (SD/Co3) has been constructed from trimeric {Co3(COO)6} clusters as SBUs and mixed ligands as linkers. It exhibits preferential selective adsorption of C2H2/C2H4, C2H2/C2H6 and CO2/N2, owing to its dual active sites including uncoordinated nitrogen sites from pyrimidine groups and unsaturated metal centres (UMCs) exposed in channels.