Xiao-Ming Lin

Lithium-Ion-Battery Anode Materials with Improved Capacity from a Metal–Organic Framework

We present a porous metal-organic framework (MOF) with remarkable thermal stability that exhibits a discharge capacity of 300 mAh g(-1) as an anode material for a lithium-ion battery. Pyrolysis of the obtained MOF gives an anode material with improved capacity (741 mAh g(-1)) and superior cyclic stability.

Two series of Ln(III)–Ag(I) heterometallic–organic frameworks constructed from isonicotinate and 2,2′-biphenyldicarboxylate: synthesis, structure and photoluminescence properties

Two new series of two-dimensional (2-D) lanthanide–silver heterometallic–organic frameworks with the formula [Ln2Ag(IN)2(BPDC)2(H2O)4]·(NO3)·2H2O (1-Ln) (Ln = Nd 1, Eu 2, Tb 3, and Dy 4) and [Ln2Ag(IN)2(BPDC)2(H2O)2]·(NO3)·2H2O (2-Ln) (Ln = Ho 5, Yb 6, HIN = isonicotinic acid, H2BPDC = 2,2′-biphenyldicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). In the structures of these six compounds, BPDC2− ligands link Ln3+ through their carboxylate groups, resulting in the formation of one-dimensional (1-D) {Ln(BPDC)}n infinite chains. These adjacent chains are further connected to each other via the coordination interaction between Ln3+ and carboxylate groups of IN− ligands, as well as the pillared Ag(IN)2 units, giving rise to 2-D layered structures. Although they have similar secondary building units (SBUs), the whole open frameworks of these two types of HMOFs that may be produced by the lanthanide contraction effect are quite different. Isostructural compounds 1–4 (1-Ln) crystallize in the monoclinic C2/c space group and possess a (6,3)-connected topology containing 1-D hexagonal microporous channels along the c axis, while isostructural compounds 5 and 6 (2-Ln) crystallize in the triclinic P space group and present a 2-D network of (4,4)-connected topology with 1-D rhombic channels along the b axis. Meanwhile, solid-state photoluminescence studies of compounds 1–3 and 6 were also conducted at room temperature and the luminescence intensity of 3 and 6 are found to be sensitive to small molecules.

Structural diversity of Mn(II), Zn(II) and Pb(II) coordination polymers constructed from isomeric pyridylbenzoate N-oxide ligands: structures and electrochemical properties

Several new coordination polymers (CPs), [Mn(4,3-opybz)2(H2O)2]n (1), [Zn(4,3-opybz)(OH)]n (2), {[Pb(4,3-opybz)(H2O)]·(NO3)}n (3), {[Mn3(4,4-opybz)4(HCOO)2(H2O)4]·6H2O}n (4), Zn(4,4-opybz)2(H2O)2 (5) and {[Pb(4,4-opybz)(4,3-opybz)]·3DMF·7H2O}n (6) (4,4-Hopybz = 4-(4-pyridyl)benzoic acid N-oxide, 4,3-Hopybz = 4-(3-pyridyl)benzoic acid N-oxide), have been successfully synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single crystal X-ray diffraction. Structural analysis shows that complex 1 features a two-dimensional (2D) layer with a 63 topology. Complexes 2 and 3 present a 2D layer architecture with a 4·82 topology. Complex 4 presents an unusual one-dimensional (1D) chain constructed with linear trinuclear secondary building units (SBUs). Complex 5 has a zero-dimensional (0D) structure which is further connected to form a 2D supramolecular network through O–H⋯O hydrogen bonding. Complex 6 exhibits a 2D layer which is further connected by π⋯π interactions to produce a three-dimensional (3D) supramolecular framework with 1D opening channels. Moreover, as an anode material, complex 6 exhibits a relatively high irreversible capacity of about 860 mA h g−1 in the first discharge process and a reversible lithium storage capacity of up to 405 mA h g−1 at 100 mA g−1 after 100 cycles. The observation of good storage performance demonstrates that CPs are a prospective class of electrode materials for lithium ion batteries (LIBs).

Four metal–organic frameworks based on a semirigid tripodal ligand and different secondary building units: structures and electrochemical performance

Four new metal–organic frameworks (MOFs), [Co3(TCPB)2(CH3OH)4]·4DMF (1), [Cd3(TCPB)2(H2O)4]·3DMF·19H2O (2), [Mn3(TCPB)2(H2O)2(DMF)2]·2DMF (3), and [Zn2(μ3-OH) (TCPB)(H2O)(DEF)]·3DEF (4) (H3TCPB = 1,3,5-tri(4-carboxyphenoxy)benzene), have been successfully synthesized and structurally characterized. Structural analyses show that complexes 1–3 present two-dimensional (3,6)-connected kgd net topology with the Schlafli symbol of (43)2(46·66·83) based on linear trinuclear M3(COO)6 (M = Co, Cd, and Mn) secondary building units (SBUs) and display distinct one-dimensional (1-D) channels. Complex 4 (Zn-TCPB) exhibits a rare three-dimensional twofold interpenetrated (3,6)-connected rutile topology with the Schlafli symbol of (42·610·83) (4·62)2 based on the tetranuclear Zn4(μ3-OH)2(COO)6 clusters, which shows three different types of 1-D opening channels. In addition, as an anode material, the complex 4 (Zn-TCPB) electrode exhibits an irreversible high capacity in the first discharge process and a reversible lithium storage capacity of up to about 455 mA h g−1 at 0.1 A g−1 after 100 cycles. This might provide a new method for finding a promising candidate for the electrode materials in lithium-ion batteries.

A versatile CuII/CuI metal–organic framework for selective sorption and heterogeneous catalysis

A three-dimensional (3-D) multi-functional mixed valence CuII/CuI-MOF, {[Cu(CuI)2(2-pyzc)2H2O]2·H2O}n (Hpyzc = pyrazine-2-carboxylic acid), has been solvothermally synthesized and successfully characterized by FT-IR spectroscopy, elemental analysis, powder X-ray diffraction, thermal gravimetric analysis (TGA) and single-crystal X-ray diffraction. The structure posesses a 3-D open framework containing 1-D channels and shows a tcj topological network with the Schlafli symbol (43·612)(43)2. This MOF exhibits selective adsorption of CO2/H2 over CH4/N2 and excellent catalytic activity in the oxidation of benzylic compounds and three-component coupling reactions of aromatic alkynes, tosyl azide and diisopropylamine as a cooperative catalyst. The catalyst could be reused several times without significant degradation in catalytic activity.

A series of variable coordination polymers based on flexible aromatic carboxylates

Six coordination polymers (CPs), namely, [Ag(tmb)]n (1), [Cu(tmb)2(H2O)]n (2), [Eu(HCOO)(tmb)2]n (3), [Ag(bimb)(Hbimb)]n (4), [Cu(bimb)2]n (5) and [Eu(bimb)3]n (6) (Htmb = 4-((1H-1,2,4-triazol-1-yl)methyl)benzoic acid), Hbimb = 4-((1H-benzo[d]imidazol-1-yl)methyl)benzoic acid), have been successfully synthesized under similar solvothermal conditions and characterized by elemental analysis, IR, thermogravimetric analysis and single-crystal X-ray diffraction. 3-D complex 1 presents a binodal (3,6)-connected rutile topology with the Schlafli symbol (42·610·83) (4·62)2. Previously reported complex 2 shows a 3-D framework of pcu topology, in which the inorganic ⋯Cu–O–Cu–O⋯ chains are connected to each other through the tmb− ligands. In 3, Eu(III) atoms are connected by carboxylate groups to form a double-helical chain, which further expands to a 3-D framework of tsi topology with the Schlafli symbol (36·416·56). Complex 4 exhibits a 1-D chain structures which are further connected by O–H⋯O hydrogen bonding and π⋯π interactions to form a 3-D supramolecular framework. Complex 5 features a two-dimensional 44 layer. In 6, Eu3+ ions are bridged by bimb− ligands to form a 1-D three-strand double-helical chain which is further connected by ligands to produce a 2-D layer with a 4·82 topology. The different structural dimensions of the six complexes (1–6) are closely related to the steric effect of the triazole ring or benzimidazole ring in the ligands. Furthermore, the fluorescence properties of 1, 3, 4, and 6 are studied in the solid state at room temperature.

From 1D to 3D lanthanide coordination polymers constructed with pyridine-3,5-dicarboxylic acid: synthesis, crystal structures, and catalytic properties

Three series of lanthanide coordination polymers with formula [Ln2(PDC)3(H2O)2(DMF)]·4H2O (type I) (Ln = La 1, Pr 2, Sm 3), [(CH3)2NH2][Ln2(PDC)3(HCOO)(H2O)3]·2H2O (type II) (Ln = Tb 4, Ho 5) and [Ln(HPDC)3(H2O)2]·H2O (type III) (Ln = Er 6, Lu 7) (H2PDC = pyridine-3,5-dicarboxylic acid), have been successfully synthesized by the solvothermal reaction of pyridine-3,5-dicarboxylic acid (H2PDC) with the corresponding lanthanide nitrate. Compounds 1–3 are isomorphous and all crystallize in triclinic space group P, showing a 3D microporous framework of pcu topology with square channels along the b-axis. Isostructural compounds 4 and 5 show the same 2D layer network of (4,4)-grid in the monoclinic P21/c space group. Isomorphic 6 and 7 crystallize in the monoclinic Cc space group and present 1D zigzag chains which expand to a 3D supramolecular structure through π⋯π stacking interactions. The structural diversity of these three classes of compounds may be attributed to the effect of lanthanide contraction. They were characterized by infrared spectra (IR), elemental analysis (EA), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and X-ray single crystal diffraction. Furthermore, the catalytic properties of these compounds were investigated and experiments revealed that compounds 1–3 show size-selective catalytic performance for cyanosilylation reactions and could be reused without losing their catalytic activity.