Three metal–organic frameworks (MOFs) [M2(d-cam)2(bimb)2]n·3.5nH2O (M = Mn for 1, Co for 2) and [Cd8(d-cam)8(bimb)4]n (3) (d-H2cam = d-camphor acid, bimb = 4,4′-bis(1-imidazolyl)biphenyl), solvothermally synthesized, exhibit structural diversity. The charming aspect of these frameworks is that compound 3 is the very first MOF-based sensor for quantitatively detecting three different types of analytes (metal ions, aromatic molecules, and pesticides). And also, both compounds 2 and 3 show rapid uptake and ready regeneration for methyl orange (MO) and can selectively bind MO over methylene blue (MB) with high MO/MB separation ratio.Keywords: dyes separation; luminescence quenching; metal−organic frameworks; quantitative detecting

A cyano-bridged {FeIII2CoII2} complex exhibits reversible thermally and photoinduced intramolecular charge transfer. Its desolvated, MeOH-d4, and other analogues were compared to disclose the impact factors on the electron-transfer behavior of these {FeIII2CoII2} clusters.

Co/Fe Prussian Blue analogues are known to display both thermally and light induced electron transfer attributed to the switching between diamagnetic {FeIILS(μ-CN)CoIIILS} and paramagnetic {FeIIILS(μ-CN)CoIIHS} pairs (LS = low spin; HS = high spin). In this work, a dinuclear cyanido-bridged Co/Fe complex, the smallest {Fe(μ-CN)Co} moiety at the origin of the remarkable physical properties of these systems, has been designed by a rational building-block approach. Combined structural, spectroscopic, magnetic and photomagnetic studies reveal that a metal-to-metal electron transfer that can be triggered in solid state by light, temperature and solvent contents, is observed for the first time in a dinuclear complex.

Solvothermal reactions of 5-(4-pyridyl)-isophthalic acid (H2pbdc) and transition-metal centers (Ni2+/Co2+/Zn2+) in the presence (or absence) of N-auxiliary 4,4′-bis(1-imidazolyl)biphenyl (bimb) ligand produce [Ni2(pbdc)2(μ2-H2O)(H2O)2·(DMA)2.7]n (DMA = N,N′-dimethylacetamide, 1), [Ni12(pbdc)12(μ2-H2O)6(py)2(H2O)8(DMA)2·(H2O)5·(DMA)9]n (2), [Co2(pbdc)2(bimb)2·(bimb)0.5·(H2O)4·(DMF)0.25]n (3) and [Zn(pbdc)(bimb)·(H2O)]n (4), which exhibit structural diversity. Both compounds 1 and 2 display a uninodal 8-connected 3D tsi net, but feature different crystal systems and space groups from each other. Compound 3 adopts a 2-fold interpenetrating binodal (3,5)-connected 3D hms net and compound 4 features a rare 2-fold interpenetrating binodal (3,4)-connected 3D fsx architecture. In particular, activated 3 shows high-efficiency for the selective sorption of small molecules, including CO2 over N2 and CH4, H2 over N2, as well as alcohols from water. More importantly, 4 represents the first report on a MOF as a promising luminescent probe for detecting pesticides, and also the very first example for detecting both pesticides and solvent molecules simultaneously.

A cyano-bridged {Fe2Co2} complex shows reversible single crystal-to-single crystal transformation between diamagnetic and paramagnetic states switched specifically by losing and absorbing methanol at room temperature in the solid state. And the solvent loss form presents temperature- and pressure-induced intramolecular electron transfer behaviour.

A Cd(II)–MOF [Cd(L)(DMF)] (1) (H2L = 5-(4-pyridyl)-isophthalic acid) featuring high thermal and chemical stability has been solvothermally synthesized and characterized. Complex 1 is a robust multifunctional three-dimensional (3D) microporous framework possessing an unusual (4,5)-connected topological net. Activated 1 shows high-efficiency for the selective capture of CO2 over N2 and CH4 under ambient conditions, which ranks it among MOFs with the highest selectivity. In addition, desolvated 1 exhibits good separation ratios of H2 over N2 at lower temperature, as well as alcohols from water. In particular, desolvated 1 demonstrates significantly higher adsorption enthalpies for CO2 and CH4 gas molecules, which are in the range of the highest Qst values reported to date. Furthermore, complex 1 displays visible photoluminescence in the solid state under UV irradiation.

A three-dimensional microporous framework, Zn(II)–MOF [Zn(HPyImDC)(DMA)]n (1) (H3PyImDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic, DMA = N,N′-dimethylacetamide), with open metal sites and small-sized pores, exhibits excellent selective capture of CO2 over N2 and CH4 at 273 K, as well as alcohols from water. The excellent CO2 adsorption selectivity of 1 allows its potential use in the capture of CO2 from industrial flue gas or the removal of CO2 from natural gas. More interestingly, compound 1 represents the rare case of porous materials separating propanol isomers, which may be caused by the relative flexibility of the linear n-propanol considering that both n-propanol and i-propanol have similar kinetic diameters.

Two three-dimensional microporous compounds, Cu6(BTTC)4(H2O)6·xS (1) and [(CH3)2NH2]3[(Cu4Cl)3(BTTC)8]·yS (2, H3BTTC = benzo-(1,2;3,4;5,6)-tris (thiophene-2′-carboxylic acid), S represents noncoordinated solvent molecules), have been solvothermally synthesized and characterized, both of which are based upon truncated octahedron subunits and contain uniform nanosized cavities but exhibit different topological frameworks. Complex 1 demonstrates high adsorption enthalpies for H2 and CO2 gas molecules, stemming principally from the presence of the exposed metal Cu(II) sites on the pore surface. In particular, activated complex 1 shows high efficiency for the separation of energy-correlated molecules, including CO2 over N2 and CH4 under ambient conditions.

Solvothermal reactions of 2-amino-1,4-benzene dicarboxylic acid (NH2bdcH2) and N-auxiliary ligands in the presence of manganese(II), zinc(II) and cobalt(II) salts have given rise to four new metal–organic frameworks, namely, [Mn5(NH2bdc)5(bimb)5·(H2O)0.5]n (bimb = 4,4′-bis(1-imidazolyl)biphenyl) (1), [Zn(NH2bdc)(bix)·(DMF)2]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (2), [Co(NH2bdc)(bix)·(DMF)·(CH3CH2OH)]n (3) and [Co(NH2bdc)(bpp)]n (4) (bpp = 1,3-bis(4-pyridyl)propane). Single-crystal X-ray diffraction analyses revealed that MOF 1 displays 5-fold interpenetrating 4-connected dia 3D net; MOFs 2 and 3 are isomorphic, which possess 3-fold interpenetrating dia 3D nets; MOF 4 exhibits 4-connected sql 2D net. Noncentrosymmetric structures and multifunctionality in 1–3 are established by varying ligands and metal centers. In the solid state, polar MOFs 1–3 exhibit nonlinear-optic (NLO) and MOF 1 demonstrates typical ferroelectric behaviour with a remnant electric polarization (Pr) of 1.2 μC cm−2 and an electric coercive field (Ec) of 0.35 kV cm−1. In addition, MOF 2 could be a potential luminescent probe for detecting nitrobenzene or 2-nitrotoluene via fluorescence enhancement and has been evaluated as a promising visible-light-driven photocatalyst for degradation of organic pollutants.

Two microporous cadmium(II) metal–organic frameworks, [Cd(cptpy)(Ac)(H2O)·(DMA)(H2O)]n (1) and [Cd(cptpy)2·(DMF)2]n (2) (Hcptpy = 4-(4-carboxyphenyl)-2,2′:4′,4″-terpyridine, DMA = N,N-dimethylacetamide, DMF = dimethylformamide) have been solvothermally synthesized under different reaction conditions. Complex 1 is a double-interpenetrating 3D network, while 2 is a noninterpenetrating (3,5)-connected 2D framework. The dehydrated forms of compounds 1 and 2 exhibit selective adsorption of CO2 over N2 and H2O over CH3OH. In addition, the adsorption value of CO2 for 2 is higher than that of 1. The contents of uncoordinated pyridine nitrogen (Lewis basic sites) per formula unit of 1 and 2 are 2.16 and 4.36%, respectively. Obviously, the grafting of more uncoordinated pyridine nitrogen into compound 2 could enhance adsorption of the acidic CO2 molecule. Notably, both 1 and 2 display strong photoluminescence. The nature of electronic transitions for complex 1 in the photoluminescent process was investigated by means of time-dependent density functional theory (TDDFT) calculations and molecular orbital analyses, which collaborates that the luminescent property is ligand-based.

Five new metal–organic frameworks [M(btec)0.5(bimb)]n (1) (M = Co (1), Ni (2), Cu (3), Zn (4)) and [Cd(btec)0.5(bimb)0.5]n (5), were obtained by reactions of the conjugated 1,2,4,5-benzenetetracarboxylic acid (H4btec) and 4,4′-bis(1-imidazolyl)biphenyl (bimb) with corresponding metal salts under hydrothermal conditions, respectively. MOFs 1-5 show different structures and topologies: compounds 1 and 4 are isomorphic, which possess typical PtS 3D nets; compound 2, 3 and 5 exhibit 2D layer structure, NbO 3D network and (4,6)-connected 3D binodal topology, respectively. Notably, compounds 1, 2, and 5 represent the rare example of MOFs-based visible-light-driven photocatalysts and show good stability toward photocatalysis. Furthermore, compound 5 is photocatalytically more active than 1 and 2 because of the relatively narrower band gap calculated from LMCT transitions. In addition, the formation rate of •OH radicals on compound 5/H2O interface via photocatalytic reactions is much higher than that of 1 and 2, implying that the formation rate of •OH radicals during photocatalysis is in agreement with photocatalytic activity and the formation rate of •OH radicals is an important factor influencing photocatalytic performance.

A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)CrIII(C≡CSiMe3)2(µ3-pz)]2·(n-pentane)2 (Tp = hydridotris(pyrazolyl) borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structure analysis shows that the complex contains a Li2Cr2 core bridged by two µ3-pyrazolates. The magnetic data exhibit the existence of weak antiferromagnetic interaction in the cluster.

The treatment of Fe(ClO4)2·6H2O or Fe(ClO4)3·9H2O with a benzimidazolyl-rich ligand, N,N,N′,N′-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,2-ethanediamine (medtb) in alcohol/MeCN gives a mononuclear ferrous complex, [FeII(medtb)](ClO4)2·½CH3CN·½CH3OH (1), and four non-heme alkoxide–iron(III) complexes, [FeIII(OMe)(medtb)](ClO4)2·H2O (2, alcohol = MeOH), [FeIII(OEt)(Hmedtb)](ClO4)3·CH3CN (3, alcohol = EtOH), [FeIII(OnPr)(Hmedtb)](ClO4)3·nPrOH·2CH3CN (4, alcohol = n-PrOH), and [FeIII(OnBu)(Hmedtb)](ClO4)3·3CH3CN·H2O (5, alcohol = n-BuOH), respectively. The alkoxide–iron(III) complexes all show 1) a Fe(III)–OR center (R = Me, 2; Et, 3; nPr, 4; nBu, 5) with the Fe–O bond distances in the range of 1.781–1.816 Å, and 2) a yellow color and an intense electronic transition around 370 nm. The alkoxide–iron(III) complexes can be reduced by organic compounds with a cis,cis-1,4-diene moiety via the hydrogen atom abstraction reaction.

Three metal-organic frameworks based on the connectivity co-effect between rigid aromatic dicarboxylic acids and flexible linear linkers have been synthesized and characterized. [Cd(3-NO2-bdc)(bbi)]n (1) and [Co(3-NO2-bdc)(bbi)]n (2) (3-NO2-bdcH2 = 3-nitro-1,2-benzenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) are isostructural, which exhibit two-dimensional (2D) layer frameworks; [Co(3,5-pdc)(bbi)·2H2O]n (3) (3,5-pdcH2 = pyridine-3,5-dicarboxylic acid) has 2D 6-connected network with a Schäfli symbol of (344653). In addition, compounds 1 and 2 exhibit good photocatalytic activities under visible irradiation, and their different photocatalytic activities have also been analyzed based on the diffuse-reflectance UV/Vis spectra.Metal-organic frameworks 1 and 2, derived of rigid aromatic dicarboxylic acid and flexible linear linkers, are isostructural, which possess two-dimensional layer frameworks and exhibit good photocatalytic activities under visible irradiation. Different photocatalytic activities have been analyzed based on the diffuse-reflectance UV/Vis spectra.Research Highlights► Three metal-organic frameworks based on the connectivity co-effect between rigid aromatic dicarboxylic acids and flexible linear linkers have been synthesized. ► Compounds 1 and 2 exhibit good photocatalytic activities under visible irradiation. ► Different photocatalytic activities for 1 and 2 have been analyzed based on the diffuse-reflectance UV/Vis spectra.

Three ferrous/ferric complexes of a N6 hexadentate ligand, N,N,N′,N′-tetrakis(2-benzimidazolyl-methyl)ortho-diamine-trans-cyclohexane (ctb), [FeII(ctb)](ClO4)2·EtOH (1), [FeIII(OEt)(Hctb)](ClO4)3·EtOH (2), and [FeIII(OMe)(Hctb)](ClO4)3·3MeOH·4.5H2O (3), were synthesized and characterized as models of lipoxygenase. The lipoxygenase activities of the complexes were checked and the results indicate that ferrous complex 1 is inactive while ferric alkoxide complexes 2 and 3 show catalytic activity via the hydrogen atom abstraction reaction mechanism.

Six metal−organic coordination polymers, [Cu(bdc)(bimb)]n (H2bdc = 1,4-benzenedicarboxylate; bimb = 4,4′-bis(1-imidazolyl)biphenyl) (1), [Cu3(btc)2(bimb)2·(H2O)3]n (H3btc = 1,3,5-benzenetricarboxylate) (2), [M3(btc)2(bimb)2·(H2O)4]n (M = Mn for 3, Co for 4, Cd for 5), and [Cd(btcH)(bimb)]n (6) were obtained under hydrothermal conditions and characterized structurally. The networks exhibit a variety of topologies: compound 1 exhibits a triply interpenetrating three-dimensional (3D) framework with a distorted primitive cubic (α-Po) single net; compounds 2−5 are isomorphic, which possess a trinodal 4-connected 3D framework; compound 6 has a two-dimensional (3,4)-connected framework. In addition, the thermal stabilities for 1−6 and the photoluminescence properties for 5 and 6 were examined. An anionic organic dye X3B was selected as a model pollutant in aqueous media to evaluate the photocatalytic effectiveness of isostructural compounds 3 and 4, and the results indicated compounds 3 and 4 represent rare examples of coordination polymers that exhibit high photocatalytic activity for dye degradation under UV light and show good stability toward photocatalysis. The difference in catalytic activity between 3 and 4 arises from the discrepancy in central metal ions of the two compounds.

A new metal-organic framework, [Zn5(trencba)2(OH)2Cl2·4H2O] (1) [H3trencba=N,N,N′,N′,N′′,N′′-tris[(4-carboxylate-2-yl)methyl]-tris(2-aminoethyl)amine], constructed from a flexible tripodal ligand based on C3 symmetric tris(2-aminoethyl)amine, has been synthesized hydrothermally and characterized by elemental analysis, IR, TG, XRD and single-crystal X-ray diffraction analysis. Compound 1 contains an unprecedented linear penta-nuclear zinc cluster fragment. Each ligand links four penta-nuclear fragments, and every fragment links eight ligands to generate a three-dimensional non-interpenetrated porous framework. The uncoordinated water molecules were observed trapped in the void pores. Compound 1 represents the first example of (6,8)-connected 3D bi-nodal framework based on a single kind of organic ligand. The photoluminescence measurements showed that complex 1 exhibits relatively stronger blue emissions at room temperature than that of the ligand.The MOF [Zn5(trencba)2(OH)2Cl2·4H2O] (H3trencba=N,N,N′,N′,N′,N′-tris[(4-carboxylate-2-yl)methyl]-tris(2-aminoethyl)amine) reveals a (6,8)-connected bi-nodal three-dimensional porous framework with unprecedented penta-nuclear fragment, which appears to be a good candidate of hybrid inorganic-organic photoactive materials.

Two 1D inorganic–organic hybrid frameworks, namely, [Zn(5-NO2-bdc)(MIM)3·H2O]n(1) and [Cd(MIM)2Br2]n(2) (5-NO2-bdcH2 = 5-nitro-1,3-benzenedicarboxylic acid, MIM = N-methyl imidazole) were synthesized via ionothermal reactions with ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) as solvent and template. Both compounds have been characterized by elemental analyses, spectroscopic analyses, thermogravimetric analysis (TGA) and the single crystal diffraction. The zinc(II) center in compound 1 is a slightly distorted five-coordinate trigonal bipyramid, 5-NO2-bdc2− anions and MIM moieties effectively bridge Zn centers to result in 1D zigzag chains. While Cd(II) center in compound 2 is in an octahedral coordination environment, and two μ2-bridge bromine link two [Cd(MIM)2] moieties to form a 1D chain structure. In addition, complex 2 exhibits strong fluorescent emission in the solid state at room temperature.

Two novel inorganic–organic hybrid frameworks of [Co(2,5-pydc)(4,4′-bipyo)0.5(H2O)3 · 3H2O]n (1) and [Cu1.5Gd(2,5-pydc)3(2,2′-bipyo)(H2O)4 · 2H2O]n (2) (2,5-pydc = pyridine-2,5-dicarboxylic acid; 4,4′-bipyo = 4,4′-bipyridine-N,N′-dioxide; 2,2′-bipyo = 2,2′-bipyridine-N,N′-dioxide) were prepared. Both compounds have been characterized by the elemental analyses, IR spectra, TG analysis and the single crystal diffraction. The salient structural feature for both compounds 1 and 2 is that the 1D chain and the mononuclear fragment are connected by strong hydrogen bond interactions to form 2D structure.

The reactions of tricyanometallate precursors, (Ph3PMe)[(Tp4-Me)Fe(CN)3·0.5CH3CN] (1) (Tp4-Me = tri(4-methyl-pyrazol-1-yl)borate) and (NBu4)[(MeTp)Fe(CN)3] (MeTp = methyltris(pyrazolyl)borate) with the presence of the tetradentate tpa ligand (tpa = tris(2-pyridylmethyl)amine) and Fe(ClO4)2·6H2O afford two new cyano-bridged mixed-valence {FeIII2FeII2} molecular squares: [(Tp4-Me)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·H2O (2·H2O) and [(MeTp)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·CH3OH (3·CH3OH). Solvent-exchange compounds of 3·CH3OH, [(MeTp)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·2H2O (3·2H2O), and their solvent-free form (2 and 3) are also obtained, respectively. The spin crossover (SCO) properties of all compounds are confirmed by detailed structural analyses of the coordination environments of the FeII centres and magnetic susceptibility measurements. All compounds exhibit SCO behaviour near room temperature (T1/2 = 320 K for 2·H2O; 302 K for 2; 292 K for 3·CH3OH; 306 K for 3·2H2O and 290 K for 3) and reversible single-crystal to single-crystal (SC–SC) transformations induced by guest desorption and resorption or solvent exchange. The transition temperature close to room temperature can be tuned by the dehydration and re-hydration processes. The structure–property analysis discloses that the distorted {Fe4(μ-CN)4} core and deviations of bent ∠Fe−NC angles play a key role in tuning the transition temperature of these similar mixed-valence {FeIII2FeII2} complexes.

A cyano-bridged {Fe2Co2} complex shows reversible single crystal-to-single crystal transformation between diamagnetic and paramagnetic states switched specifically by losing and absorbing methanol at room temperature in the solid state. And the solvent loss form presents temperature- and pressure-induced intramolecular electron transfer behaviour.

A three-dimensional microporous framework, Zn(II)–MOF [Zn(HPyImDC)(DMA)]n (1) (H3PyImDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic, DMA = N,N′-dimethylacetamide), with open metal sites and small-sized pores, exhibits excellent selective capture of CO2 over N2 and CH4 at 273 K, as well as alcohols from water. The excellent CO2 adsorption selectivity of 1 allows its potential use in the capture of CO2 from industrial flue gas or the removal of CO2 from natural gas. More interestingly, compound 1 represents the rare case of porous materials separating propanol isomers, which may be caused by the relative flexibility of the linear n-propanol considering that both n-propanol and i-propanol have similar kinetic diameters.

A Cd(II)–MOF [Cd(L)(DMF)] (1) (H2L = 5-(4-pyridyl)-isophthalic acid) featuring high thermal and chemical stability has been solvothermally synthesized and characterized. Complex 1 is a robust multifunctional three-dimensional (3D) microporous framework possessing an unusual (4,5)-connected topological net. Activated 1 shows high-efficiency for the selective capture of CO2 over N2 and CH4 under ambient conditions, which ranks it among MOFs with the highest selectivity. In addition, desolvated 1 exhibits good separation ratios of H2 over N2 at lower temperature, as well as alcohols from water. In particular, desolvated 1 demonstrates significantly higher adsorption enthalpies for CO2 and CH4 gas molecules, which are in the range of the highest Qst values reported to date. Furthermore, complex 1 displays visible photoluminescence in the solid state under UV irradiation.

The treatment of Fe(ClO4)2·6H2O or Fe(ClO4)3·9H2O with a benzimidazolyl-rich ligand, N,N,N′,N′-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,2-ethanediamine (medtb) in alcohol/MeCN gives a mononuclear ferrous complex, [FeII(medtb)](ClO4)2·½CH3CN·½CH3OH (1), and four non-heme alkoxide–iron(III) complexes, [FeIII(OMe)(medtb)](ClO4)2·H2O (2, alcohol = MeOH), [FeIII(OEt)(Hmedtb)](ClO4)3·CH3CN (3, alcohol = EtOH), [FeIII(OnPr)(Hmedtb)](ClO4)3·nPrOH·2CH3CN (4, alcohol = n-PrOH), and [FeIII(OnBu)(Hmedtb)](ClO4)3·3CH3CN·H2O (5, alcohol = n-BuOH), respectively. The alkoxide–iron(III) complexes all show 1) a Fe(III)–OR center (R = Me, 2; Et, 3; nPr, 4; nBu, 5) with the Fe–O bond distances in the range of 1.781–1.816 Å, and 2) a yellow color and an intense electronic transition around 370 nm. The alkoxide–iron(III) complexes can be reduced by organic compounds with a cis,cis-1,4-diene moiety via the hydrogen atom abstraction reaction.

Three ferrous/ferric complexes of a N6 hexadentate ligand, N,N,N′,N′-tetrakis(2-benzimidazolyl-methyl)ortho-diamine-trans-cyclohexane (ctb), [FeII(ctb)](ClO4)2·EtOH (1), [FeIII(OEt)(Hctb)](ClO4)3·EtOH (2), and [FeIII(OMe)(Hctb)](ClO4)3·3MeOH·4.5H2O (3), were synthesized and characterized as models of lipoxygenase. The lipoxygenase activities of the complexes were checked and the results indicate that ferrous complex 1 is inactive while ferric alkoxide complexes 2 and 3 show catalytic activity via the hydrogen atom abstraction reaction mechanism.

Solvothermal reactions of 5-(4-pyridyl)-isophthalic acid (H2pbdc) and transition-metal centers (Ni2+/Co2+/Zn2+) in the presence (or absence) of N-auxiliary 4,4′-bis(1-imidazolyl)biphenyl (bimb) ligand produce [Ni2(pbdc)2(μ2-H2O)(H2O)2·(DMA)2.7]n (DMA = N,N′-dimethylacetamide, 1), [Ni12(pbdc)12(μ2-H2O)6(py)2(H2O)8(DMA)2·(H2O)5·(DMA)9]n (2), [Co2(pbdc)2(bimb)2·(bimb)0.5·(H2O)4·(DMF)0.25]n (3) and [Zn(pbdc)(bimb)·(H2O)]n (4), which exhibit structural diversity. Both compounds 1 and 2 display a uninodal 8-connected 3D tsi net, but feature different crystal systems and space groups from each other. Compound 3 adopts a 2-fold interpenetrating binodal (3,5)-connected 3D hms net and compound 4 features a rare 2-fold interpenetrating binodal (3,4)-connected 3D fsx architecture. In particular, activated 3 shows high-efficiency for the selective sorption of small molecules, including CO2 over N2 and CH4, H2 over N2, as well as alcohols from water. More importantly, 4 represents the first report on a MOF as a promising luminescent probe for detecting pesticides, and also the very first example for detecting both pesticides and solvent molecules simultaneously.

Solvothermal reactions of 2-amino-1,4-benzene dicarboxylic acid (NH2bdcH2) and N-auxiliary ligands in the presence of manganese(II), zinc(II) and cobalt(II) salts have given rise to four new metal–organic frameworks, namely, [Mn5(NH2bdc)5(bimb)5·(H2O)0.5]n (bimb = 4,4′-bis(1-imidazolyl)biphenyl) (1), [Zn(NH2bdc)(bix)·(DMF)2]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (2), [Co(NH2bdc)(bix)·(DMF)·(CH3CH2OH)]n (3) and [Co(NH2bdc)(bpp)]n (4) (bpp = 1,3-bis(4-pyridyl)propane). Single-crystal X-ray diffraction analyses revealed that MOF 1 displays 5-fold interpenetrating 4-connected dia 3D net; MOFs 2 and 3 are isomorphic, which possess 3-fold interpenetrating dia 3D nets; MOF 4 exhibits 4-connected sql 2D net. Noncentrosymmetric structures and multifunctionality in 1–3 are established by varying ligands and metal centers. In the solid state, polar MOFs 1–3 exhibit nonlinear-optic (NLO) and MOF 1 demonstrates typical ferroelectric behaviour with a remnant electric polarization (Pr) of 1.2 μC cm−2 and an electric coercive field (Ec) of 0.35 kV cm−1. In addition, MOF 2 could be a potential luminescent probe for detecting nitrobenzene or 2-nitrotoluene via fluorescence enhancement and has been evaluated as a promising visible-light-driven photocatalyst for degradation of organic pollutants.