Nanostructured metal oxides derived from metal organic frameworks have been shown to be promising materials for application in high energy density lithium ion batteries. In this work, porous nanostructured ZnCo2O4 and Co3O4 were synthesized by a facile and cost-effective approach via the calcination of MOF-74 precursors and tested as anode materials for lithium ion batteries. Compared with Co3O4, the electrochemical properties of the obtained porous nanostructured ZnCo2O4 exhibit higher specific capacity, more excellent cycling stability and better rate capability. It demonstrates a reversible capacity of 1243.2 mAh/g after 80 cycles at 100 mA/g and an excellent rate performance with high average discharge specific capacities of 1586.8, 994.6, 759.6 and 509.2 mAh/g at 200, 400, 600 and 800 mA/g, respectively. The satisfactory electrochemical performances suggest that this porous nanostructured ZnCo2O4 is potentially promising for application as an efficient anode material for lithium ion batteries.Porous ZnCo2O4 with large surface area and pore volume was fabricated via annealing MOF-74 precursor, which exhibited high-performance tested as anode materials for lithium ion batteries.Download high-res image (266KB)Download full-size image

Four Cd(II)-based compounds (1–4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.

Rechargeable nonaqueous Li–O2 batteries have been considered as one of the most promising candidate energy storage devices. In this work, metal–organic framework nanomaterials with distinct sizes and morphologies were successfully synthesized via a facile solvothermal method. By using modulators in a mixed solvent system, the dimension of Co-MOF-74 could be reduced down to several unit cell lengths. Furthermore, high specific capacities (11 350 mA h g−1 at 100 mA g−1) were achieved when they were directly employed as cathode materials for Li–O2 batteries. In addition to the high density of unsaturated active sites for electrochemistry, as provided by the MOF skeleton itself, the size confinement and inherent defects of the nanocrystals have further offered efficient diffusion paths with lowered transport barriers, contributing to their high performance in Li–O2 batteries.

•Porous rod-shaped Co3O4 was simply fabricated via annealing Co-MOF-74 precursor.•The similar morphology and porous structure of precursor were retained after calcining.•It exhibited high-performance tested as anode materials for lithium ion battery due to the unique porous rod-shaped structure.Porous rod-shaped Co3O4 has been successfully synthesized by one-step thermal annealing of the as-prepared Co-MOF-74 precursor and tested as anode materials for lithium ion batteries. The porous rod-shaped Co3O4 is found to be very attractive for lithium-ion batteries. It demonstrates a reversible capacity of 683 mAh/g after 80 cycles at 100 mA/g and an excellent rate performance with high average discharge specific capacities of 1231, 1026, 733 and 502 mAh/g at 50, 100, 200 and 400 mA/g, respectively. The excellent electrochemical performance should be due to the porous structural and composition characteristics.Porous rod-shaped Co3O4 was simply fabricated via annealing Co-MOF-74 precursor. The similar morphology and porous structure of precursor were retained after calcining. The as-synthesized sample exhibited high-performance tested as anode materials for lithium ion batteries due to the unique porous rod-shaped structure.Download high-res image (114KB)Download full-size image

•Two new amino-functionalized Zn(II) coordination polymers•Structural diversity due to the flexibility of dicarboxylate ligands•Crystallographic and spectroscopic properties exploredTwo flexible V-shaped dicarboxylate coligands (H2IBG = isophthaloylbisglycine, and H2PPDA = 4,4′-(perfluoropropane-2,2-diyl)dibenzoic acid) were selected to construct two new amino-functionalized coordination polymers based on Zn salt and a rigid linear ligand L (L = 3,6-di(3-imidazolyl)benzene-1,2-diamine. Both {[Zn(PPDA)(L)]·3H2O}n (1) and {[Zn2(IBG)(L)]·2H2O}n (2) were crystallized in mononuclear structure. Complex 1 shows a 3-D super structure based on ABAB packing, while complex 2 shows a 2-D layered structure. Structural diversity was acquired due to the flexibility of dicarboxylate ligands. Crystallographic and spectroscopic properties of both complexes were explored.

•Three new amino-functionalized coordination polymers from mononuclear to multinuclear coordination modes were constructed.•The structural diversity in assembly process is determined by the flexibility of dicarboxylate ligands.Three amino-functionalized coordination polymers with different flexible V-shaped dicarboxylate ligands have been synthesized based on Cd salt and a rigid linear ligand L (L = 3,6-di(3-imidazolyl)benzene-1,2-diamine, H2HIP = 5-hydroxyisophthalic acid, H2ABA = bis(4-carboxylphenyl)amine, H2IBG = isophthaloylbisglycine): {[Cd(L)1.5(HIP)]·(H2O)}n (1), {[Cd2(L)(ABA)2(H2O)]·(H2O)2}n (2) and {[Cd(L)0.5(IBG)]·(H2O)2}n (3). Complex 1 crystallizes in a mononuclear structure with a 3D hxg-d net. Complex 2 crystallizes in a tetranuclear fashion with a layer structure. Complex 3 shows an infinite rod-shaped secondary building unit (SBU) structure. It implies that the structural diversity in assembly process is determined by the flexibility of dicarboxylate ligands. These complexes were characterized by single crystal X-ray diffraction, infrared spectra, thermogravimetric analysis, elemental analysis, and powder X-ray diffraction measurements. Additionally, luminescent properties of 1–3 have also been explored and all exhibit significant red-shifted emission in the solid state at room temperature compared with free L ligand.Three new amino-functionalized coordination complexes from mononuclear to multinuclear coordination were generated. The structural diversity in assembly process is determined by the flexibility of dicarboxylate ligands.

Reducing the particle size of active component in electrode material could significantly improve the electrochemical performance of lithium-ion batteries. Herein, we report a facile method for preparing cobalt oxide nanoparticles–reduced graphene oxide (Co3O4–RGO) nanocomposite, which was composed of ultra-small Co3O4 nanoparticles (∼12.5 nm in size) anchored on RGO nanosheets, as anode material for lithium-ion batteries. Both of the Co3O4–RGO nanocomposite and Co3O4 nanoparticles showed very high specific surface areas of ∼149.5 m2 g−1 and ∼107.4 m2 g−1. The Co3O4–RGO nanocomposite showed excellent coulombic efficiency, high lithium storage capacity and good rate capability. With an optimum weight percentage of RGO (∼40 wt%), the nanocomposite displayed a high reversible discharge capacity of 830.7 mA h g−1 after 75 cycles at 200 mA g−1, and a reversible capacity of 680.9 mA h g−1 after 30 cycles at 200 mA g−1 and 100 consecutive cycles at 500 mA g−1. After each eight cycles at 50, 100, 200, and 500 mA g−1, the nanocomposite showed high reversible specific capacities of about 1153.2, 961.0, 851.4 and 736.4 mA h g−1, respectively. These results show the importance of anchoring ultra-small nanoparticles on graphene nanosheets for maximum utilization of electrochemically active Co3O4 nanoparticles and graphene for energy storage applications in high-performance lithium-ion batteries.

Two Zn(II)-based metal–organic frameworks, namely, [Zn3(Hbptc)2(DMF)2]·2DMF(1) and [Zn5(bptc)3(H2O)]((CH3)2NH2)2(2), (H4bptc = 3,3′,5,5′-biphenyltetracarboxylic acid, DMF = N,N′-dimethylformamide), have been synthesized using different amounts of nitric acid under mixed-solvothermal conditions. 1 and 2 display different coordination geometries and donor ligands for the Zn2+ ions. In 1, only three carboxylic acid groups of H4bptc take part in the construction of the three-dimensional (3-D) framework with Zn2+, and one remains uncoordinated that can bind to other metal ions. Postsynthetic exchange of 1 with Ln3+ cations demonstrates that 1 can effectively capture metal cations and sensitize the visible-emitting Ln3+.

Five new metal–organic frameworks (MOFs), {[Zn2(BPPA)2(BDC)2]·6H2O}n (1), {[Cd3(BPPA)(BDC)2(DMF)2]·DMF·3H2O}n (2), {[Zn(BPPA)(NDC)1/2(HCO2)]}n (3), {[Zn3(BPPA)3(TFBDC)3]·H2O}n (4), and {[Cd2(BPPA)2(TFBDC)2]}n (5), have been synthesized from the self-assembly of the “V-shape” BPPA ligand with Zn/Cd metal salts, incorporating coligands (H2BDC = 1,4-benzenedicarboxylic acid, H2NDC = 2,6-naphthalenedicarboxylic acid, TFBDC = 2,3,5,6-tetrafluoroterephthalic acid, BPPA = bis(4-(pyridine-4-yl)phenyl)amine, DMF = N,N-dimethylformamide). Compound 1 is a 4-fold interpenetrated three-dimensional (3D) network with sra topology. Compound 2 is the first 2-fold interpenetrated sxa topology, which is reported only non-interpenetration before. Compound 3 is a one-dimensional chain by utilizing a “longer” rigid H2NDC coligand. Via a “fatter” rigid TFBDC ligand, we control interpenetration by one-pot synthesis. Both compounds 4 and 5 are non-interpenetrated 3D 6T8 frameworks, and the 6T8 topology has rarely been reported in MOFs before. Interestingly, carboxyl groups in 1–5 adopt various coordinate modes. Luminescent properties of 1–5 have also been explored, and the emission decay lifetimes of 4 and 5 are longer than compounds 1–3 and free ligands because of a fluorescent synergistic effect. This may provide an feasible way to exploit materials with long emission decay lifetimes.

Nanocrystals of ZIF-8 have been successfully prepared in the presence of non-ionic triblock copolymers P123 and F127 under microwave irradiation. Noticeably, the reaction time could be significantly reduced down to 1 min. The obtained ZIF-8 nanocrystals had sizes of sub-104 nm and exhibited a high BET surface area of 1599 m2 g−1. This approach is expected to be an efficient and environmentally friendly method for the preparation of ZIF-8.

Three new manganese coordination polymers, {[Mn2(1,4-NDC)2(phen)2](H2O)}n (1), [Mn2(1,4-NDC)2(phen)(H2O)]n (2) and {[Mn4(1,4-NDC)4(phen)4](DMF)2}n (3) (1,4-H2NDC = 1,4-naphthalene dicarboxylic acid; phen = 1,10-phenanthroline; DMF = N,N-dimethylformamide), have been synthesized solvo/hydrothermally. 1,4-NDC2− ligands adopt different coordination modes under different solvents and concentrations which promotes different crystal structure formation. X-ray crystal structural data reveal that compounds 1, 2 and 3 crystallize in monoclinic space groups C2/c, P21/c and C2/c, respectively. Compound 1 has Mn2 dimers connected by 1,4-NDC2− linkers, packing into a 2D structure in a grid pattern. Compound 2 has a three-dimensional (3D) structure which is constructed by Mn2 dimers and 1,4-NDC2− linkers. Each MnO4N2 node of compound 3 is linked to another by 1,4-NDC2− ligands to form a two-dimensional (2D) structure. Variable-temperature magnetic susceptibilities of compounds 1–3 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.

A new three-dimensional (3D) manganese coordination polymer, [Mn2(IP)1.5(HCOO)(DEF)]n (1) (H2IP = isophthalic acid, DEF = N,N-diethylformamide), has been solvothermally synthesized in DEF. X-ray single crystal structural data reveal that compound 1 crystallizes in orthorhombic space group Fdd2 and was constructed with infinite zig-zag chains of corner- and edge-sharing octahedral (MnO6)n units interconnected by isophthalate to form a 3D framework. The in situ generated formate ions from the hydrolysis of DEF adopt a special bridging mode to build the secondary building units (SBUs). Variable-temperature magnetic susceptibility of compound 1 exhibits overall weak antiferromagnetic coupling between the adjacent Mn2+ ions.A new 3D manganese coordination polymer [Mn2(IP)1.5(HCOO)(DEF)]n (H2IP = isophthalic acid) has been solvothermally synthesized in N,N-diethylformamide (DEF) with in situ generated formate ions.

•The first successful synthesis of ZIF-8 in aqueous system under microwave irradiation•The products exhibit high surface area and large micropore volume.•This strategy can be widely used in synthesis of other ZIFs.Herein we report a new strategy to synthesize zeolitic imidazolate framework-8 (ZIF-8) at a relatively low molar ratio of ligand to metal ion in aqueous solution under microwave irradiation for the first time. The products possess high surface area and large micropore volume. The molar ratio of ligand to metal ion and the salt anion play an important role on the size and shape of ZIF-8.Zeolitic imidazolate framework-8 (ZIF-8) was successfully synthesized by a new microwave irradiation method in aqueous solution for the first time.

Two new magnesium coordination polymers, [Mg(9,10-ADC)(H2O)2(DMF)2]n(1) and [Mg6(1,4-NDC)5(HCO2)4(DMF)(H2O)]n·2n[H2N(CH3)2]·2n(DMF) (2) (9,10-ADC = 9,10-anthracenedicarboxylate; 1,4-NDC = 1,4-naphthalenedicarboxylate) have been solvothermally synthesized. Compound 1 displays a one-dimensional linear chain structure, which is orderly constructed from magnesium metal cations connecting with carboxylic oxygen atoms of 9,10-H2ADC along the a axis. Compound 2 exhibits a three-dimensional framework composed of infinite chains of corner-sharing octahedral MgO6 with 1,4-NDC ligands forming one-dimensional channels along the a axis, where guest molecules reside. When guest molecules are removed, no structural transformation is found to occur, generating a robust structure with permanent porosity. The studies of CO2 absorption suggest that compound 2 is a promising adsorbent material for CO2.Graphical abstractHighlights► Two magnesium coordination polymers were prepared. ► Compound 1 adopts a one-dimensional linear chain structure. ► Compound 2 exhibits a three-dimensional Porous structure. ► Compound 2 is a good adsorbent material for CO2.

Two manganese coordination polymers, [Mn2(ip)2(dmf)]·dmf (1) and [Mn4(ip)4(dmf)6]·2dmf (2) (ip=isophthalate; dmf=N,N-dimethylformamide), have been synthesized and characterized. X-ray crystal structural data reveal that compound 1 crystallizes in triclinic space group P−1, a=9.716(3) Å, b=12.193(3) Å, c=12.576(3) Å, α=62.19(2)°, β=66.423(17)°, γ=72.72(2)°, Z=2, while compound 2 crystallizes in monoclinic space group Cc, a=19.80(3) Å, b=20.20(2) Å, c=18.01(3) Å, β=108.40(4)°, Z=4. Variable-temperature magnetic susceptibilities of compounds 1 and 2 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.Graphical abstractThree-dimensional porous and two-dimensional layered manganese isophthalates have been prepared. Magnetic susceptibility measurements exhibit overall weak antiferromagnetic interactions between the Mn(II) ions in both compounds.Highlights► Two manganese isophthalates have been prepared. ► Compound 1 adopts a three-dimensional porous structure. ► Compound 2 adopts a two-dimensional layered structure. ► Magnetic properties of both compounds are investigated.

Two new complexes, namely, Co(IDC)(phen) (1) and [Co(PrIDC)(phen)]n⋅nH2O (2) (H3IDC = 4,5-imidazoledicarboxylic acid, H3PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, and phen = 1,10-phenanthroline) have been hydrothermally synthesized and structurally characterized. Complex 1 crystallizes in a tetranuclear fashion with a square ring-like structure. Complex 2 shows an infinite one-dimensional chain structure, in which the six-coordinated Co3+ exhibits distorted octahedral geometry. It is particularly worth noting that the existence of the substitute group of 2-position in the 4,5-imidazoledicarboxylate ligand plays a critical role in the formation of the resulting diverse topological structures. The fluorescence properties of complexes 1 and 2 in the solid state have also been investigated.Two cobalt-imidazole-based dicarboxylate complexes have been prepared. The substitute group plays a critical role in the formation of the resulting structures. The fluorescence properties of both compounds are investigated.Highlights► Two cobalt-imidazole-based dicarboxylate complexes have been prepared. ► Compound 1 adopts square ring-like structure. ► Compound 2 adopts a one-dimensional chain structure. ► The substitute group plays a critical role in the formation of the resulting structures.

•Hierarchical ZIF-67 with micro-, meso-, and macropore was conducted.•The pore size and proportion of meso- and macropore increased as TMB increased.•The particle size was enlarged under the effect of 1,3,5-trimethylbenzene.A hierarchically porous ZIF-67 was successfully synthesized by using non-ionic block copolymers P123 as a supramolecular templating surfactant and 1,3,5-trimethylbenzene (TMB) as a swelling agent. It was noted that TMB was an effective swelling agent to expand the pore size. Pore size distribution analyses reveal that the as-synthesized hierarchical ZIF-67 has a typical trimodal pore size distribution showing simultaneous micro-, meso- and macropore channel systems. Due to the effect of TMB and P123, the diameter of ZIF-67 nanoparticles was about twice of that synthesized with P123 only and larger pores were formed among the enlarged nanoparticles. This strategy is expected to be a facile and efficient method for the preparation of hierarchical ZIF-67.Hierarchical ZIF-67 with micro-meso-macroporous structure was synthesized under the effects of P123 and 1,3,5-trimethylbenzene (TMB). The pore size was increased under the swelling effect of TMB.

Rechargeable nonaqueous Li–O2 batteries have been considered as one of the most promising candidate energy storage devices. In this work, metal–organic framework nanomaterials with distinct sizes and morphologies were successfully synthesized via a facile solvothermal method. By using modulators in a mixed solvent system, the dimension of Co-MOF-74 could be reduced down to several unit cell lengths. Furthermore, high specific capacities (11350 mA h g−1 at 100 mA g−1) were achieved when they were directly employed as cathode materials for Li–O2 batteries. In addition to the high density of unsaturated active sites for electrochemistry, as provided by the MOF skeleton itself, the size confinement and inherent defects of the nanocrystals have further offered efficient diffusion paths with lowered transport barriers, contributing to their high performance in Li–O2 batteries.

Three new manganese coordination polymers, {[Mn2(1,4-NDC)2(phen)2](H2O)}n (1), [Mn2(1,4-NDC)2(phen)(H2O)]n (2) and {[Mn4(1,4-NDC)4(phen)4](DMF)2}n (3) (1,4-H2NDC = 1,4-naphthalene dicarboxylic acid; phen = 1,10-phenanthroline; DMF = N,N-dimethylformamide), have been synthesized solvo/hydrothermally. 1,4-NDC2− ligands adopt different coordination modes under different solvents and concentrations which promotes different crystal structure formation. X-ray crystal structural data reveal that compounds 1, 2 and 3 crystallize in monoclinic space groups C2/c, P21/c and C2/c, respectively. Compound 1 has Mn2 dimers connected by 1,4-NDC2− linkers, packing into a 2D structure in a grid pattern. Compound 2 has a three-dimensional (3D) structure which is constructed by Mn2 dimers and 1,4-NDC2− linkers. Each MnO4N2 node of compound 3 is linked to another by 1,4-NDC2− ligands to form a two-dimensional (2D) structure. Variable-temperature magnetic susceptibilities of compounds 1–3 exhibit overall weak antiferromagnetic coupling between the adjacent Mn(II) ions.

Four Cd(II)-based compounds (1–4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.

Reducing the particle size of active component in electrode material could significantly improve the electrochemical performance of lithium-ion batteries. Herein, we report a facile method for preparing cobalt oxide nanoparticles–reduced graphene oxide (Co3O4–RGO) nanocomposite, which was composed of ultra-small Co3O4 nanoparticles (∼12.5 nm in size) anchored on RGO nanosheets, as anode material for lithium-ion batteries. Both of the Co3O4–RGO nanocomposite and Co3O4 nanoparticles showed very high specific surface areas of ∼149.5 m2 g−1 and ∼107.4 m2 g−1. The Co3O4–RGO nanocomposite showed excellent coulombic efficiency, high lithium storage capacity and good rate capability. With an optimum weight percentage of RGO (∼40 wt%), the nanocomposite displayed a high reversible discharge capacity of 830.7 mA h g−1 after 75 cycles at 200 mA g−1, and a reversible capacity of 680.9 mA h g−1 after 30 cycles at 200 mA g−1 and 100 consecutive cycles at 500 mA g−1. After each eight cycles at 50, 100, 200, and 500 mA g−1, the nanocomposite showed high reversible specific capacities of about 1153.2, 961.0, 851.4 and 736.4 mA h g−1, respectively. These results show the importance of anchoring ultra-small nanoparticles on graphene nanosheets for maximum utilization of electrochemically active Co3O4 nanoparticles and graphene for energy storage applications in high-performance lithium-ion batteries.

A high quality crystalline porous coordination polymer (PCP), Fe(OH)(1,4-NDC)·2H2O (1,4-NDC = 1,4-naphthalenedicarboxylate), was successfully prepared using a rapid and efficient microwave irradiation method (hereafter termed M-PCP-Fe). It was noteworthy that the microwave irradiation method reduced the reaction time considerably to 1 min, while it took three days for the conventional hydrothermal method to prepare non-uniform crystal morphologies in a one-pot manner (hereafter termed H-PCP-Fe). The effects of microwave irradiation time, temperature and concentration were also investigated. According to the CO2 adsorption isotherms, it was found that M-PCP-Fe had a better performance on CO2 adsorption than H-PCP-Fe under the same conditions. This approach is expected to be widely used in large scale production of PCPs.