A new rigid and symmetrical tetracarboxylic ligand 2,3,5,6-tetrakis(4-carboxyphenyl)pyrazine (H4TCPP) with aggregation-induced emission effect has been designed and synthesized. By using such a ligand, a novel multifunctional metal–organic framework Zn-TCPP has been successfully constructed. The cross-linkage of dinuclear Zn2(COO)4 clusters and organic TCPP4– ligands results in the three-dimensional channel structure of Zn-TCPP, which has a four connected lvt topology with the point symbol of {42.84}. Zn-TCPP not only displays bright blue luminescence arising from the matrix coordination-induced emission effect of the TCPP4– ligand, but also exhibits effective detection for picric acid and Fe3+ ions. In addition, the activated Zn-TCPP possesses a highly porous framework with a Brunauer–Emmett–Teller surface area of 984 m2 g–1 and CO2 adsorption capacity up to 135 cm3 g–1 at 273 K and 732 mmHg. This work represents a successful example of constructing metal–organic frameworks with desired functions based on the designed organic ligand.

Luminescent porous organic polymers have shown potential applications in sensing, light-harvesting, photocatalysis and photo-voltaic or electronic devices. In this paper, a luminescent porous Tröger's base polymer (LMOP-15) with a tetraphenylethene unit has been synthesized by a simple method through the reaction of 1,1,2,2-tetrakis(4-aminophenyl)ethene and dimethoxymethane in acid solution at room temperature. The N2 adsorption of LMOP-15 at 77 K reveals the type I isotherm of microporous materials, and the calculated Brunauer–Emmett–Teller surface area is 484 m2 g−1. The CO2 uptake capacity of LMOP-15 at 273 K and 1 bar is 48.8 cm3 g−1, while the isosteric heat for CO2 reaches 53.7 kJ mol−1 due to the presence of the Tröger's base moiety. The CO2/N2 adsorption selectivity calculated from the initial slopes of the CO2 and N2 adsorption isotherms at 273 K is up to 61.7. LMOP-15 also exhibits strong green luminescence (λmax = 517 nm) in ethanol suspension. Furthermore, LMOP-15 shows highly selective fluorescence quenching detection abilities for Cu2+ ions and picric acid.

Two new metal–organic frameworks based on a cationic 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium bromide (H2ipbpBr) ligand have been designed and synthesized by varying the solvents and counterions to adjust the coordination modes between organic linkers and metal ions. Both of them possess two dimensional (2D) neutral layered frameworks, which show photochromic and photo-modulated luminescence properties. Compound 1 is photo-active in response to UV light, while 2 is sensitive to visible and UV light, accompanied by color transformation from light yellow to brown and green, respectively. Furthermore, compound 1 exhibits interesting selective vapochromism to diethylamine (DEA), and the vapochromic sample can be easily recovered when washed with MeOH, which offers a simple, convenient and recyclable vapor sensor for organic gas emissions. This work provides abundant scope to explore novel MOF materials with useful photo-active and colorimetric sensor properties.

A three-dimensional microporous metal–organic framework assembled from a T-shaped pyridyl dicarboxylate ligand, 4′-(pyridin-4-yl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H2PBPD), has been successfully synthesized via solvothermal reaction with copper(II) nitrate. Compound 1 was characterized by X-ray single-crystal diffraction, elemental analysis, IR spectroscopy and thermogravimetric analyses. Single-crystal X-ray diffraction analysis indicates that compound 1 is a (3,6)-connected three-dimensional framework with the point symbol {42·6}2{44·62·86·103}. In the framework of this compound, there exist two large metal–ligand cages. Stability tests show that compound 1 keeps its crystal structure after being soaked in several organic solvents or calcined at 250 °C under air atmosphere. The N2 adsorption at 77 K shows that compound 1 is microporous with a BET surface area of 1682 m2 g−1. Compound 1 possesses high adsorption capacities for CO2 (114 cm3 g−1, 273 K) under ambient pressure. The test of CO2 cyclic adsorption and regeneration of 1 shows that it has a stable CO2 adsorption capacity and no obvious weight change after doing this ten times.

Crystalline chromic materials coupled with other functionalities are of particular interest due to their multiple external stimuli responsive properties. In this work, a new photochromic and hydrochromic metal–organic framework based on a bipyridinium carboxylate cationic 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium bromide (H2ipbpBr) ligand and a luminescent Eu3+ ion has been successfully designed and synthesized. [Eu(ipbp)2(H2O)3]·Br·6H2O (1) is photo-active under both UV and visible light irradiation accompanied by an obvious color change from light yellow to green owing to the formation of ipbp radicals under light stimulus. Meanwhile, compound 1 exhibits unique hydrochromic properties, and the reversible color change between light yellow and dark green caused by electron transfer can be induced by release/reabsorption of guest water molecules accompanied by a structure transformation. Moreover, the luminescence properties and two-dimensional layered cationic network of 1 endow it with excellent sensing ability for Cr2O72− and CrO42− anions. This work will provide a new perspective to design smart MOF materials that can serve as practical multi-responsive sensors to light, water, and chemicals.

A series of imidazole ionic liquid (IL) functionalized porous organic polymers (POPs) with high surface areas has been successfully prepared based on p-dichloroxylene (p-DCX) and N-methylimidazole (N-MI) as fundamental building blocks through the FeCl3-catalyzed Friedel–Crafts alkylation reaction. The IL-functionalized POPs show CO2 uptake up to 73.6 cm3 g−1 (273 K, 1 bar). Their isosteric heat of adsorption can be increased from 7.84 to 17.35 kJ mol−1 by adjusting the molar ratios of N-MI to p-DCX. These materials could also be used as reusable acid catalysts in the syntheses of benzimidazole derivatives from aromatic aldehydes and o-phenylene diamine in good yields (87–91%).

Two novel zinc metal–organic frameworks [Zn3(TPT)2(DMF)2]·0.5HNMe2 (1) and NH2Me2·[Zn(TPT)]·DMF (2) have been synthesized by using Zn(II) ions and p-terphenyl-3,4′′,5-tricarboxylic acid (H3TPT). The structures of these two MOFs are dependent on the solvents used in the synthetic processes. Compound 1 was synthesized in a mixture of DMF and H2O, while compound 2 was obtained in the presence of DMF and ethanol. The three-dimensional (3D) framework of 1 is constructed by the connection of Zn–carboxylate chains and TPT3− linkers. The structure of 2 can be described as a 3,6-connected network based on the assembly of binuclear zinc clusters and TPT3− ligands. These two MOFs exhibit ligand-based photoluminescence at around 375 nm, as well as high efficiency for the recyclable detection of nitroaromatic explosives.

A series of novel 3D lanthanide metal–organic frameworks based on unsymmetrical 1,2,3-triazole-containing tricarboxylic acid ligand 5-[4-(4-carboxy-phenyl)-[1,2,3]triazol-1-yl]-isophthalic (H3TAIP) has been synthesized under solvothermal conditions. The ligand was synthesized with diethyl-5-azidoisophthalate and 4-ethynyl-benzoic acid ethyl ester through the copper-catalyzed azide alkyne cycloaddition (CuAAC) reaction. Single-crystal X-ray diffraction analyses reveal that these metal–organic frameworks are isostructural. The structures are constructed by bi-nuclear lanthanide metal clusters and TAIP3− ligands and possess flu-3,6-C2/c net with point symbol (42.6)2(44.62.87.102). We explore the luminescence properties of compound 1, which shows the characteristic emission of Tb3+ and exhibits selective detection of 4-nitrophenol and Fe3+ ions in ethanol solution over other nitroaromatic compounds and metal ions.

The Heck coupling reaction of vinyl-terminated double four-ring siloxane cages (octavinylsilsesquioxane) with aromatic bromide monomers (4,4′-dibromobiphenyl, 1,4-dibromonaphthalene, 2,6-dibromonaphthalene and 1,2-bis(4-bromophenyl)-1,2-diphenylethene) was used to construct a class of luminescent nanoporous inorganic–organic hybrid polymers (PS-n). The structures of these polymers were confirmed by solid state 13C CP/MAS and 29Si MAS NMR spectra, as well as Fourier transform infrared spectroscopy (FTIR). The results identify polymers with Brunauer–Emmett–Teller (BET) surface areas of up to 685 m2 g−1. The luminescence properties of these polymers were utilized for picric acid detection. Furthermore, PS-1-n (n = 6, 12, 24, 48 or 72 h) samples polymerized for different lengths of time were investigated for their energy transfer behaviour with Coumarin 6.

A microporous lanthanum metal–organic framework [La(TPT)(DMSO)2]·H2O (La-MOF (1)), has been synthesized using a rigid unsymmetrical tricarboxylate ligand of p-terphenyl-3,4′′,5-tricarboxylic acid (H3TPT). The structure of 1 is constructed by bi-nuclear lanthanum clusters and fully deprotonated TPT3− ligands, which can be simplified into a 3,6-connected flu-3,6-C2/c topology with a point symbol of (44·6)2(4·62·87·102). The π-electron rich ligand H3TPT enables 1 to have blue luminescence when excited at 342 nm at ambient temperature. Meanwhile, 1 exhibits the selective detection of picric acid (PA) and Fe3+ ions in ethanol solution over other nitroaromatic compounds and metal ions. The high quenching efficiency and selectivity of 1 makes it a potential bi-functional chemosensor for both PA and Fe3+ ions.

A novel metal–organic framework [Cd3(TPT)2(DMF)2]·(H2O)0.5 (1) has been solvothermally synthesized using a new rigid unsymmetrical tricarboxylate ligand p-terphenyl-3,4′′,5-tricarboxylic acid (H3TPT). Single-crystal X-ray diffraction analysis reveals that 1 possesses a three-dimensional (3D) framework with an alb-4,8-C2/c topology constructed by the combination of Cd–carboxylate chains and TPT linkers. The π-electron rich ligand H3TPT enables 1 to have an excellent luminescent property. The micrometer-sized compound 1′ dispersed in ethanol exhibits high efficiency detection for picric acid (PA). The high efficiency, stability and recyclability of 1′ make it a potential chemosensor for nitroaromatic explosives.

A series of luminescent microporous organic polymers (LMOPs) have been synthesized by a new synthetic methodology through the palladium catalyzed tandem Suzuki–Heck C–C coupling reactions of several aromatic halides with potassium vinyltrifluoroborate. These polymers are porous with the BET surface areas from 318 to 693 cm2 g−1. The formation of conjugated polymers with the incorporation of vinyl groups leads to the fluorescent properties, and the luminescence of LMOPs could be adjusted from blue to green by selecting the aromatic halides and alternating the ratio of monomers. The fluorescence quenching behaviors of these LMOPs by nitroaromatic analytes in ethanol are investigated. It is found that the fluorescence of the polymers can be effectively quenched by picric acid (PA).

A zeolitic metal–organic framework with a SOD topology, (Et2NH2)[In(BCBAIP)]·4DEF·4EtOH (H4BCBAIP: 5-(bis(4-carboxybenzyl)amino)isophthalic acid) (1), has been constructed by a 4 + 4 synthetic strategy from tetrahedral organic building units and In3+ ions. Compound 1 could adsorb organic dyes and be used as a light-harvesting antenna.

A novel class of luminescent microporous organic polymers (LMOPs) has been constructed by Heck coupling reactions of 1,3,5-tri(4-ethenylphenyl)benzene with aromatic halides. These polymers are microporous with the BET surface areas ranging from 391 to 791 m2 g−1 and possess quite narrow pore distributions at around 0.66 and 0.68 nm. The incorporation of 1,3,5-tri(4-ethenylphenyl)benzene into these polymers gives rise to the high luminescence, and the selection of aromatic halides could adjust the emissions from blue to green. The emissions of LMOPs could be quenched efficiently by picric acid, indicating that these polymers could be utilized as sensors for explosive detection.

Two novel porous copper-based metal–organic frameworks with nbo and agw topologies have been designed and synthesized using tetracarboxylate and tricarboxylate ligands, respectively. They possess large surface areas and high CO2 adsorption capacities (up to 170 cm3/g or 7.59 mmol/g at 0 °C under ambient pressure).

A novel metal–organic framework [Cd3(CPEIP)2(DMF)3]·solvent (1) based on a neutral non-oxo triangular [Cd3(COO)6] secondary building unit (SBU), was synthesized under solvothermal conditions by using a rigid unsymmetrical tricarboxylate ligand 5-((4-carboxyphenyl)ethynyl)isophthalic acid (H3CPEIP). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group C2/c. The crystal structure exhibits a rare (3,3,6)-connected three-dimensional (3-D) framework with vertex symbol of (42.6)(43)(45.64.86). The incorporation of CPEIP3+ into 1 gives rise to high luminescence in solid state. The emission of micrometer-sized compound 1 (1′) dispersed in ethanol could be quenched efficiently by picric acid (PA), indicating that this compound could be utilized as a chemosensor for detection of aromatic explosives.

A novel decanuclear Co(II) cluster, [Co10(Q)12(μ6-CO3)4]·2.5DMF (1) (Q = 8-hydroxyquinoline), has been synthesized under solvothermal conditions and characterized by powder XRD, TGA and IR spectroscopy. Single-crystal X-ray diffraction analysis shows that 1 represents a new type of decanuclear cobalt cluster with an approximate supertruncated tetrahedral shape coordinated with coexisted Q ligands and in situ formed μ6-bridging CO32− anions. Meanwhile, 1 is the largest aggregate in metal–Q coordination chemistry. Another distinguishing feature of 1 is the adamantane-like metallic skeleton with point symbol {63}2{6}3, which is observed in the polynuclear metal complexes for the first time. Furthermore, it is considered that the in situ formed CO32− anions have a crucial effect on the formation of the resultant unexpected polynuclear structures. The magnetic studies show that antiferromagnetic (AF) interactions exist within 1.

A family of 3D lanthanide metal–organic frameworks, [La(HTADIP)(H2O)4]·xH2O (2 < x < 2.5) (1), [Eu(HTADIP)(H2O)4]·H2O (2), [Tb(HTADIP)(H2O)3]·2H2O (3), and [Er(HTADIP)(H2O)3]·2H2O (4) (H4TADIP = 5,5′-(1H-1,2,3-triazole-1,4-diyl)diisophthalic acid), have been hydrothermally synthesized and characterized. The unsymmetrical 1,2,3-triazole-containing tetracarboxylate ligand was synthesized through the copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction of diethyl-5-azidoisophthalate (M1) and diethyl-5-ethynylisophthalate (M2). Single-crystal X-ray diffraction analyses for 1–4 reveal that they are isostructural. These compounds crystallize in the monoclinic P21/c space group with the rutile topology. The luminescent properties of compounds 2 and 3 were investigated and characteristic Eu(III) and Tb(III) emissions are observed. Compound 3 exhibits selective luminescent sensing behavior for Cu2+ ions in aqueous solution. The magnetic properties of compounds 3 and 4 were studied.

A new 3D lanthanide metal-organic framework with rare flu-3,6-C2/c topology, [Tb(CPEIP)(DMF)(H2O)]·2H2O (1) (DMF = N, N-dimethylformamide), has been synthesized using novel tricarboxylate ligand 5-((4-carboxyphenyl)ethynyl)isophthalic acid (H3CPEIP). It crystallizes in monoclinic space group C2/c. The structure is constructed from metallic 6-connected and organic 3-connected building units with point symbol of (426)2(446287102). The fluorescent properties of compound 1 and organic ligand were studied.A new 3D lanthanide metal-organic framework with rare flu-3,6-C2/c topology, [Tb(CPEIP)(DMF)(H2O)]·2H2O (1) (DMF = N, N-dimethylformamide), has been synthesized using novel tricarboxylate ligand 5-((4-carboxyphenyl)ethynyl)isophthalic acid (H3CPEIP). It possesses 3D cross-linked channels.Research Highlights► A new 3D lanthanide MOF has been synthesized using novel tricarboxylate ligand. ► The (3,6)-connected net of compound 1 has been rarely observed in MOFs. ► Compound 1 possesses three dimensional channel system.

A novel inorganic–organic hybrid compound [Mn(teta)][Mn(teta)(H2O)2]2{V18O42(Cl)}·8H2O (1) (teta: triethylenetetramine) has been hydrothermally synthesized and characterized by TGA, IR and XPS analysis. Its structure is determined by single-crystal X-ray diffraction analysis. Compound 1 exhibits a rare 2-D planar square lattice (sql net), which was constructed by the well known {V18O42} cluster as node and two distinct Mn (II) complexes, [Mn(teta)] and [Mn(teta)(H2O)2], as single/double μ2-bridging linkers. This type sql net with two distinct Mn (II) complexes is the first example found in polyoxovanadates. The magnetic study shows that there exists antiferromagnetic interaction within 1.A novel inorganic–organic hybrid solid [Mn(teta)][Mn(teta)(H2O)2]2{V18O42(Cl)}·8H2O (1) (teta: triethylenetetramine) has been synthesized. It features 2-D planar network constructed by {V18O42(Cl)} cluster and two distinct Mn (II) complexes: [Mn(teta)] and [Mn(teta)(H2O)2] as single/double μ2-bridging linkers, which is the first example found in polyoxovanadates.Highlights► 1 was constructed by {V18O42(Cl)} cluster and distinct Mn (II) complexes. ► 1 contains two distinct Mn (II) complexes as single/double μ2-bridging linkers. ► The sql net with two distinct Mn (II) complexes is rare in polyoxovanadates.

A novel decanuclear Co(II) cluster, [Co10(Q)12(μ6-CO3)4]·2.5DMF (1) (Q = 8-hydroxyquinoline), has been synthesized under solvothermal conditions and characterized by powder XRD, TGA and IR spectroscopy. Single-crystal X-ray diffraction analysis shows that 1 represents a new type of decanuclear cobalt cluster with an approximate supertruncated tetrahedral shape coordinated with coexisted Q ligands and in situ formed μ6-bridging CO32− anions. Meanwhile, 1 is the largest aggregate in metal–Q coordination chemistry. Another distinguishing feature of 1 is the adamantane-like metallic skeleton with point symbol {63}2{6}3, which is observed in the polynuclear metal complexes for the first time. Furthermore, it is considered that the in situ formed CO32− anions have a crucial effect on the formation of the resultant unexpected polynuclear structures. The magnetic studies show that antiferromagnetic (AF) interactions exist within 1.

Two new metal–organic frameworks based on a cationic 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium bromide (H2ipbpBr) ligand have been designed and synthesized by varying the solvents and counterions to adjust the coordination modes between organic linkers and metal ions. Both of them possess two dimensional (2D) neutral layered frameworks, which show photochromic and photo-modulated luminescence properties. Compound 1 is photo-active in response to UV light, while 2 is sensitive to visible and UV light, accompanied by color transformation from light yellow to brown and green, respectively. Furthermore, compound 1 exhibits interesting selective vapochromism to diethylamine (DEA), and the vapochromic sample can be easily recovered when washed with MeOH, which offers a simple, convenient and recyclable vapor sensor for organic gas emissions. This work provides abundant scope to explore novel MOF materials with useful photo-active and colorimetric sensor properties.

A novel metal–organic framework [Cd3(TPT)2(DMF)2]·(H2O)0.5 (1) has been solvothermally synthesized using a new rigid unsymmetrical tricarboxylate ligand p-terphenyl-3,4′′,5-tricarboxylic acid (H3TPT). Single-crystal X-ray diffraction analysis reveals that 1 possesses a three-dimensional (3D) framework with an alb-4,8-C2/c topology constructed by the combination of Cd–carboxylate chains and TPT linkers. The π-electron rich ligand H3TPT enables 1 to have an excellent luminescent property. The micrometer-sized compound 1′ dispersed in ethanol exhibits high efficiency detection for picric acid (PA). The high efficiency, stability and recyclability of 1′ make it a potential chemosensor for nitroaromatic explosives.

A novel metal–organic framework [Cd3(CPEIP)2(DMF)3]·solvent (1) based on a neutral non-oxo triangular [Cd3(COO)6] secondary building unit (SBU), was synthesized under solvothermal conditions by using a rigid unsymmetrical tricarboxylate ligand 5-((4-carboxyphenyl)ethynyl)isophthalic acid (H3CPEIP). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group C2/c. The crystal structure exhibits a rare (3,3,6)-connected three-dimensional (3-D) framework with vertex symbol of (42.6)(43)(45.64.86). The incorporation of CPEIP3+ into 1 gives rise to high luminescence in solid state. The emission of micrometer-sized compound 1 (1′) dispersed in ethanol could be quenched efficiently by picric acid (PA), indicating that this compound could be utilized as a chemosensor for detection of aromatic explosives.

A family of 3D lanthanide metal–organic frameworks, [La(HTADIP)(H2O)4]·xH2O (2 < x < 2.5) (1), [Eu(HTADIP)(H2O)4]·H2O (2), [Tb(HTADIP)(H2O)3]·2H2O (3), and [Er(HTADIP)(H2O)3]·2H2O (4) (H4TADIP = 5,5′-(1H-1,2,3-triazole-1,4-diyl)diisophthalic acid), have been hydrothermally synthesized and characterized. The unsymmetrical 1,2,3-triazole-containing tetracarboxylate ligand was synthesized through the copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction of diethyl-5-azidoisophthalate (M1) and diethyl-5-ethynylisophthalate (M2). Single-crystal X-ray diffraction analyses for 1–4 reveal that they are isostructural. These compounds crystallize in the monoclinic P21/c space group with the rutile topology. The luminescent properties of compounds 2 and 3 were investigated and characteristic Eu(III) and Tb(III) emissions are observed. Compound 3 exhibits selective luminescent sensing behavior for Cu2+ ions in aqueous solution. The magnetic properties of compounds 3 and 4 were studied.

A microporous lanthanum metal–organic framework [La(TPT)(DMSO)2]·H2O (La-MOF (1)), has been synthesized using a rigid unsymmetrical tricarboxylate ligand of p-terphenyl-3,4′′,5-tricarboxylic acid (H3TPT). The structure of 1 is constructed by bi-nuclear lanthanum clusters and fully deprotonated TPT3− ligands, which can be simplified into a 3,6-connected flu-3,6-C2/c topology with a point symbol of (44·6)2(4·62·87·102). The π-electron rich ligand H3TPT enables 1 to have blue luminescence when excited at 342 nm at ambient temperature. Meanwhile, 1 exhibits the selective detection of picric acid (PA) and Fe3+ ions in ethanol solution over other nitroaromatic compounds and metal ions. The high quenching efficiency and selectivity of 1 makes it a potential bi-functional chemosensor for both PA and Fe3+ ions.

A zeolitic metal–organic framework with a SOD topology, (Et2NH2)[In(BCBAIP)]·4DEF·4EtOH (H4BCBAIP: 5-(bis(4-carboxybenzyl)amino)isophthalic acid) (1), has been constructed by a 4 + 4 synthetic strategy from tetrahedral organic building units and In3+ ions. Compound 1 could adsorb organic dyes and be used as a light-harvesting antenna.