Syntheses,Structures,Luminescence and Magnetic Properties of Three New Metal-organic Frameworks Based on Rigid Carbazole Ligand

Three new metal-organic frameworks [Cd（L）（obba）]·H）2O（1）,[Co（L）（obba）]·MeCN（2） and [Cd_2（L）_2（ip）_2]·6H_2O·DMF（3）（H_2obba = 4,4？-oxybisbenzoic acid,H2 ip = m-phthalic acid） have been successfully synthesized based on the controllable self-assembly of 9-ethyl-3,6-diimidazolyl-carbazole（L）,varied carboxylates and different metal ions under solvothermal conditions,which were characterized by single-crystal X-ray diffraction,elemental analysis,IR spectroscopy and thermogravimetry. Furthermore,luminescence and magnetic susceptibility of compound 2 are also investigated in detail. Single-crystal X-ray diffraction and topology analysis reveal that complexes 1~3 exhibit similar two-dimensional（2D） networks.

Two Cd(Ⅱ)Metal-organic Frameworks(MOFs)Derived from a Triazine-based Flexible Polycarboxylate Ligand:Syntheses,Crystal Structures and Luminescence

Two new metal-organic frameworks, {[Cd2CI（HL）（H20）2＂0.5H20]}n （1） and {[Cd2L（H20）2]＇H20}n （2）, have been hydrothermally synthesized with designed ligand H4L （HaL = 1,3,5-triazine-2-iminodiacetic acid-4,6-biglycine） under the same condition except for different pH values. Single-crystal X-ray determination shows that they are 3-D frameworks. Complex 1 crystallizes in monoclinic, space group P21/n. Complex 2 crystallizes in triclinic, space group Pi. The photoluminescence properties of those two complexes have been investigated in solid state. Complexes 2 exhibited remarkable blue luminescence emissions with high quantum yield of 40.3% On the other hand, complexes 1 featured weak quantum yields of 13.7%.

Synthesis,Crystal Structure and Blue Photoluminescence of a Metal-organic Framework Constructed from Triangular [Zn_3(μ_3-OH)] Clusters with Bis(tetrazole)amine Ligands

A new metal-organic framework, {Zn[Zn3（BTA）3（μ3-OH）（H2O）3]2}n 1, has been synthesized under hydrothermal reaction of ZnCl2 and bis（5-tetrazolyl）amine （H2BTA）, and characterized by elemental analysis, FT-IR, Raman spectrum, X-ray single-crystal diffraction, TGA and photoluminescence measurements. Compound 1 crystallizes in the trigonal system, space group P-3cl, a = 13.667（3）, c = 12.981（3） A, V = 2099.6（8） A3 and Z = 2. The BTA2- ligand in 1 assumes theμ3 tetradentate mode with both 1,2- and 1,4-tetrazole bridges, generating an unusual 2-D layer, in which the [Zn3（μ3-OH）] triangular motifs act as three-connecting nodes and the mononuclear Zn atoms as six-connecting nodes that are inter-linked by organic ligands. Adjacent 2-D metal-organic layers are linked by strong hydrogen bonds to form a novel 3-D supramolecular framework. Complex 1 exhibits blue fluorescence emission in the solid state at ambient temperature.

Amplified circularly polarized luminescence of chiral metal-organic frameworks via post-synthetic installing pillars

Post-synthetic installation strategy is an effective approach to improve the functions of metal-organic frameworks(MOFs).Herein,a pair of chiral MOFs is successfully constructed through solvothermal subcomponent self-assembly and exhibit circularly polarized luminescence(CPL).These MOFs contain coordinatively unsaturated Zn sites and channels,which allow the installation of pyridyl-terminated pillars into the original structure.Such a post-synthetic installation process reinforces the MOFs'rigidity and increases the photoluminescence quantum yields(PLQYs).Furthermore,the luminescence dissymmetry factors(glum)of these post-modified MOFs are amplified after installing the pillars.This work provides an appealing strategy for boosting the CPL performance of chiral MOFs.

A New 3-Fold Interpenetrating 3D Zn(Ⅱ) Metal-organic Framework: Synthesis,Structure and Luminescent Property

A new Zn（Ⅱ） coordination polymer,namely {[Zn_（1.5）（1,3,5-btc^（3-））（dtb）（H_2O）]（H_2O）_2}_n（1）（1,3,5-H_3btc = 1,3,5-benzenetricarboxylic acid,dtb = 1,3-di-（1,2,4-triazole-4-yl）benzene）,has been hydrothermally synthesized and structurally characterized. X-ray single-crystal diffraction determination reveals that 1 crystallizes in the monoclinic C2/c space group with a = 33.811（12）,b = 8.406（2）,c = 17.296（4） ？,β = 120.593（2）°,V = 4232（2） ？~3,Z = 4,Mr = 1142.88,Dc = 1.794 Mg/m^3,μ = 1.783 mm^（-1）,F（000） = 2320,the final R = 0.0338 and wR = 0.0827 for 3043 observed reflections with I 〉 2σ（I）. Compound 1 exhibits 1D Zn（Ⅱ）-carboxylate chains,which are connected into a 3D porous framework with large channels by dtb,and then three identical 3D networks are interpenetrated with each other. In addition,the luminescence property of the complex has also been investigated.

Breaking Mirror Circularly Polarized Luminescence of Chiral Metal-Organic Frameworks by High-Pressure Stimulation

Understanding high-pressure-stimulated circularly polarized luminescence(CPL)of enantiomers remains a challenging but significant task in fundamental research and optical applications.Here,we combined in situ high-pressure photoluminescence with circularly polarized light to study how high pressure stimulated the CPL of crystalline enantiomers.Chiral lanthanide(Ln)-tartrate(Tar)metal-organic frameworks(MOFs;Ln=Eu,Tb)were synthesized to study their CPL from atmospheric pressure to 10 GPa.Under atmospheric pressure,D-and L-Eu(Tar)showed strong andmirror CPL.CPL intensity changes,emission wavelength shifts,and signal inversions were induced by increasing pressure.Note that the D-Eu(Tar)enantiomer showed strong CPL with a maximal dissymmetric factor(g_(lum))of 0.69 under 3 GPa,which is much higher than that under atmospheric pressure and of other reported MOF-based CPL materials.More interestingly,D-and L-Ln(Tar)enantiomers display obvious asymmetric CPL signals with increasing pressure,demonstrating that high pressure can break the mirror CPL of the MOF enantiomers.Our findings provide a critical understanding on in situ high-pressure CPL of chiral materials and establish a new optical phenomenon where high pressure can break the mirror CPL of enantiomers.

Construction of a Pillared-layer Framework Based on Charge Balance:CO2 Adsorption and Luminescence

Via the strategy of charge balance,one new pillared layered metal-organic framework [Zn2（TNB）（2-nim）]（H3TNB = 4,4？,4？？-nitrilotribenzoicacid,2-nim = 2-nitroimidazole）（1） was successfully synthesized based on mixed ligands,where binuclear [Zn2（CO2）3]~＋ cluster-based cationic layers [Zn2（TNB）]~＋ are connected by deprotonated 2-nitroimidazole.Meanwhile,CO2 adsorption bahaviors and luminescent property of compound 1 were investigated.

Water-sensitive multicolor luminescence in lanthanide-organic framework for anti-counterfeiting

The developme nt of high-level an ti-co un terfeiti ng tech niq ues is of great sig nifica nee in econo mics and security issues.However,i ntricate read ing methods are required to obta in multi-level info rmati on stored in differe nt colors,which greatly limits the applicati on of an ti-co un terfeit ing tech no logy on sol ving real world problems.Here in,we realize multicolor information anti-counterfeiting under simply external stimulation by utilizing the functional groups and multiple emission centers of lanthanide metal organic framework(Ln-MOFs)to tune luminescence color.Water responsive multicolor luminescence represented by both the tunable color from red to blue within the visible region and high sensitive responsivity has bee n achieved,owing to the in creased nonr adiative decay pathways and enhan ced Eu3+-to-liga nd en ergy back tra nsfer.Remarkably,i nfo rmatio n hidde n in differe nt colors n eeds to be read with a specific water content,which can be used as an en crypti on key to en sure the security of the info rmati on for high-level an ti-co un terfeiti ng.

Synthetic Control of Thorium Metal-Organic Frameworks for Sequencing and Sensing of Radioiodine Species

Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste accumulation.However,unlocking the full potential of these materials is largely crippled by the radiotoxicity of the actinides.We report here two porous and luminescent thorium-based metal-organic frameworks(Th-BITD-1 and Th-BITD-2)that serve as a bifunctional platform for sequencing and sensing of radioiodine,a much more radioactive fission product discharged during the nuclear fuel reprocessing.In particular,Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g,respectively.Fur thermore,Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant(Ksv)of 6.6(5)×10^(3) M^(-1)and a detection limit of 2.02μM,respectively,outperforming 2.96(6)×10^(3)M^(-1)and 10.5μM of Th-BITD-2.Moreover,a positive correlation between the sensing efficacy and the iodate adsorption capacity has been revealed.This work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields,e.g.,radionuclide separation and detection.

Induced Absolute Configuration of Achiral Tetradentate Ligands in Metal–Organic Frameworks for Circularly Polarized Luminescence

The crystallization of chiral molecules is of great significance to understand the origin and evolution of hierarchical chirality and reveal the relationships between structural chirality and circularly polarized luminescence(CPL)activity.Here,we report two pairs of chiral metal–organic frameworks(MOFs)(DCF-17/LCF-17,DCF-18/LCF-18)by utilizing tetradentate ligands tetra(3-imidazoylphenyl)ethylene(TIPE)and 4,4'-[4',5'-bis[4-(4-pyridinyl)phenyl][1,1':2',1”-terphenyl]-4,4”-diyl]bis[pyridine](TPPP)as linkers.It can be observed that the spontaneous resolution of the achiral ligands is converted into the induced resolution,and the ligands form the absolute configuration by using enantiopure camphoric acid(cam)as chiral induced reagent(CIR).As a result,the racemate MOFs can be driven to generate absolute homochiral crystallization.Another two achiral MOFs[Cd(D-cam)(TPPP)_(0.5)](AF-1,AF=achiral framework)and[Cd(L-cam)(TPPP)_(0.5)](AF-2)were prepared.The position disorder of D/L-cam skeleton causes the generation of nonchiralization,further leading to disappearance of symmetry breaking of TPPP.For the perspective of structure,this is the first report which reveals the chiral transfer and nonchiralization between chiral induced agents and tetradentate ligands.Besides,DCF-17 and LCF-17 show CPL with luminescence dissymmetry factor(glum)of–1.0×10^(-2)and+9.2×10^(–3),respectively.This work provides the useful evidences to reveal the induced chiral crystallization and the construction of CPL-active crystalline materials.

A Three-dimensional Tm(Ⅲ)-Zn(Ⅱ)Heteronuclear Metalorganic Framework Based on Imidazole-dicarboxylate Ligand:Synthesis,Crystal Structure and Luminescence Property

A d-f heteronuclear metal-organic framework（MOF）,{[Tm3Zn6（bipy2）2（mimda）7（H2O）3]·（H2O）5}n（1,H3 mimda = 2-methyl-1-H-imidazole-4,5-dicarboxylic acid,and bipy = 4,4？-bipyridine）,has been synthesized under solvothermal conditions,and structurally characterized by elemental analysis,IR spectra and X-ray single-crystal diffraction.It crystallizes in orthorhombic system,space group Pnma with a = 16.1102（9）,b = 33.5805（19）,c = 16.8593（10） ？,β = 97.344（11）°,V = 9120.7（9） ？-3,Z = 4,F（000） = 5184,the final R = 0.0530 and w R = 0.1306.In complex 1,the Tm（Ⅲ） ions adopt two types of coordination fashions.Complex 1 shows onedimensional（1-D） Tm-Zn heteronuclear zigzag chains,and these chains are further linked by H3 mimda ligands into Tm-Zn heteronuclear 2-D lattice-like arrays.The 2-D heteronuclear units were connected through [Zn6（mimda）6] rings to give rise to the Tm-Zn heteronuclear cages.Finally,H3 mimda ligands connected the cages into a 3-D heterometallic framework by the combination of [TmO7]n and Tm-Zn heteronuclear cages.In addition,the thermal stability and luminescent property have been investigated.

Visual and portable detection of metronidazole realized by metal-organic framework flexible sensor and smartphone scanning

Metronidazole(MNZ)is a type of antibiotic that can help people and animals cure bacterial in fections,however,abuse of MNZ has posed a threat to human health.Hence,portable and vi sual detection of MNZ is meaningful for food safety and rational administration of drugs,bu full of challenges.Hence,a porous three-dimensional Tb-based metal-organic framework(MOF{(CH_(3))_(2)NH_(2)·[Tb_(5)(TDA)_(8)(H_(2)O)_(2)]·6DMF·2C_(2)H_(5)OH}_n(TDA-Tb)with good solvent and p H stabilities was pre pared,and the framework possesses one-dimensional channels with a diameter of 12 A along the c-axis Experiment results suggest that the synthesized TDA-Tb can selectively and sensitively detect MNZ in water,and the limit of detection(LOD)is as low as 4.1×10^(-7)mol/L.Moreover,a flexible sensor TDA Tb-M was also constructed by incorporating TDA-Tb into membrane materials for convenient usage.And the TDA-Tb-M firstly realized portable and visual detection of MNZ through smartphone scanning,which may inspire more probes with wide application ranges.

A hydrogen-bonded organic framework containing fluorescent carbazole and responsive pyridyl units for sensing organic acids

Hydrogen-bonded organic frameworks(HOFs)are a promising candidate for optical sensing,but the lack of effective design strategies poses significant challenges to the construction of HOFs for organic acid sensing.In this work,the first HOF for organic acid sensing is reported by constructing a multiplepyridine carbazole-based dense HOF,namely HOF-FJU-206,from a tripyridine-carbazole molecular 3,6-bis(pyridin-4-yl)-9-(4-(pyridin-4-yl)phenyl)-9H-carbazole(CPPY)with carbazole center for luminescence,pyridyl sites for its responsive of hydrogen proton,and narrow channels in the dense framework for the diffusion of hydrogen protons.HOF-FJU-206 exhibits differential responsively fluorescence sensing and recovery properties to formic,acetic,and propionic acids with different molecular sizes and p Kavalue(acid dissociation constant).The dissociation degree of various acids can be determined by analyzing the slope of changes in both peak wavelength and intensity of in-situ fluorescence,which easily enables the dual-corrective recognition of different acids.The varying degree of protonation at pyridine sites is proved to be the reason for differential sensing of various acids,as demonstrated by1H NMR spectra,X-ray photoelectron spectroscopy(XPS)characterization,and modeling studies.

Europium-bearing organic framework with excellent X-ray scintillating luminescence

Two europium-bearing organic frameworks,termed as EuTPO-1 and EuTPO-2(H_(3)TPO=tris(4-carboxylphenyI)-phosphineoxide),are reported in this work.A series of characterizations of EuTPO-1and EuTPO-2,such as X-ray crystallography and photoluminescence spectroscopy,was performed to expatiate their structure and physicochemical properties.Both of them are constructed by dimers of the europium-oxygen subunit of [Eu_(2)O_(16)] and TPO molecule.Benefiting from high X-ray stopping attenuation and excellent luminescence efficiency,they emit sufficient luminescence when irradiated with Xrays.Meanwhile,they possess stable light outputs when exposed to high humidities and strong radiation dose,outperforming the commercial scintillator CsI:Tl.This result paves the way for developing new scintillator and enriches the compound of europium-bearing organic framework with X-ray scintillating luminescence.

Crystal Structure,Fe^(3+) Luminescence Sensing and Color Tuning of 2D Lanthanide-metal-organic Frameworks Constructed from Tricarboxylic Acid Ligand

A new lanthanide metal-organic framework (MOF)[Eu(BTB)(phen)(DMF)]·DMF (1,DMF=N,N-dimethylformamide) was synthesized using H_(3)BTB (1,3,5-tri(4-carboxyphenyl)benzene) and phen(1,10-phenanthroline) under solvothermal conditions.The structure of the prepared MOF was characterized by single-crystal X-ray diffraction analyses,elemental analysis,fluorescence spectrum,FT-IR spectroscopy,powder X-ray diffraction and thermogravimetric analyses.The structure of 1 can be viewed as a 3-D supramolecular network,which is formed by the stacking of 2D layers throughπ-πinteraction.The luminescence explorations revealed that 1 possesses favorable selectivity and sensitivity for testing Fe^(3+).Additionally,color tuning was achieved by varying Eu^(3+):Tb^(3+)ratios in the reaction mixtures.

Synthesis,structure and luminescence properties of metal-organic frameworks based on benzo-bis(imidazole)

Metal-organic frameworks(MOFs)constructed from conjugated organic ligands are candidates for hybrid photoactive materials with potential applications.Compared to that from the ligands only,the intensity and wavelength of the luminescence could be tuned after they were incorporated in extended framework.In this report,by using an organic ligand with azolate moiety,benzo-bis(imidazole)(H2BBI),we synthesized two new MOF structures.Framework 1([Co(H2BBI)(DMSO)2Cl2]n,DMSO=dimethyl sulfoxide),constructed from tetrahedral Co(II)and H2BBI,exhibits zigzag 1D structure.Meanwhile,framework 2([Cu2(H2BBI)3(DMSO)6(NO3)4]n),a layered structure with hcb topology,was assembled from tetragonal pyramidal Cu(II)and H2BBI.Furthermore,2 exhibits strong luminescence emission(ex=280 nm).A blue shift of 40 nm(from 359 nm to 319 nm)was observed in framework 2 compared to the free ligand,which could be explained by the ligand-to-metal charge transfer in the network.

Metal-organic frameworks of lanthanide iminodiacetates and tartrates:Synthesis,structural characterization and luminescence properties——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Two series of lanthanide-containing metal-organic frameworks(Ln-MOFs)of the general formula{[Ln(HIDA)_(2)H_(2)O]ClO_(4)·H_(2)O}_n(Ln=La(1),Nd(2),Eu(3),Gd(4),Tb(5),Eu:Tb(6);H_(2)IDA=iminodiacetic acid)and[Ln(TT)(HTT)(H_(2)O)_3]_n(Ln=Eu(7),Gd(8),Tb(9),Dy(10),and Eu:Tb(11);H_(2)TT=tartaric acid)were synthesized by reacting Ln(ClO_(4))_3 with iminodiacetic acid and L-tartaric acid,respectively.All compounds were structurally characterized by single-crystal X-ray diffraction.Elemental analyses are co nsistent with the corre sponding crystallographically generated formulas.Mo reover,the luminescence properties of both the single and mixed-lanthanide complexes were studied.Near infrared,red,and green emissions that are characteristic of Nd(Ⅲ),Eu(Ⅲ),and Tb(Ⅲ)are observed for 2,3/7,and 5/9,respectively.For the two mixed-lanthanide complex systems 6 and 11,depending on the relative amount of Eu(Ⅲ)and Tb(Ⅲ),the color of emission can be fine-tuned.It is found that a small amount of Eu(Ⅲ)is adequate for the observation of the most intense transition of Eu(Ⅲ).This is believed to be a result of energy transfer from Tb(Ⅲ)to Eu(Ⅲ)within the same complex-a conclusion supported by the significantly shortened lifetime of Tb(Ⅲ)and the accompanying enhanced lifetime of Eu(Ⅲ)in the mixedlanthanide complex with respect to the corresponding values for the pure Tb(Ⅲ)and Eu(Ⅲ)complexes with the same ligand.

Planar Chiral[2.2]Paracyclophane-Based Zr(IV)Metal-Organic Frameworks

Self-assembly has been widely explored to improve the circularly polarized_(lum)inescence(CPL)activities of molecular chromophores,but it is hard to amplify CPL while maintaining strong emissions.Optically pure,planar-chiral[2.2]paracyclophane(pCp)is one of the most important sources of chirality for electronic and optoelectronic materials,but the photo_(lum)inescence of its derivatives is significantly quenched after forming aggregates.Here we demonstrate that reticulation of pCp chromophores into highly stable Zr(IV)metal-organic frameworks(MOFs)can simultaneously boost the dissymmetry factor(|g_(lum)|)and_(lum)inescence efficiency(Φ_(PL)).Functionalization of pCp enables the synthesis of two tetracarboxylate linkers with different side arms,which are assembled into two highly stable Zr-MOFswith different topological structures.Geometrical constraints and segregated arrangements of the pCp chromophores imposed by the framework inhibit the aggregation-caused quenching effect and boost their CPL behaviors.Both Zr-MOFs display strong CPL emissions,affording|g_(lum)|andΦ_(PL)values of up to 8.3×10^(-3)and 87%,respectively,which are amplified by∼18-and 52-fold compared to the corresponding free ligands.This work highlights the potential of optimizing CPL performances of chiral chromophores by using MOFs as support structures.

Recent advances in luminescent metal-organic frameworks for chemical sensors

Metal-organic frameworks(MOFs),comprised of metal ions/clusters and organic ligands,have shown promising potential for numerous applications.Recently,luminescent MOFs(LMOFs),with the superiorities of inherent crystallinity,definite structure,tunable pore,and multiple functionalizations,have bloomed out as sensors for the detection.Numerous LMOFs have been synthesized and used for sensing applications.Herein,the recent advances of LMOFs as chemical sensors for the detection of diverse targets,including metal ions,anions,small molecules,volatile organic compounds,nitro-aromatic explosives,gases,and biomolecules,have been summarized.Additionally,the detection mechanisms and the relationship between structure and properties of the materials are also illustrated.This review could be useful reference for the rational construction and sensing applications of LMOFs.

Luminescent metal-organic frameworks for nitro explosives detection

Metal-organic frameworks （MOFs） have been emerging as important multifunctional hybrid materials, not only due to the diversify framework architectures, but also contribute to the rich interactions among metals, ligands and guests. Nitro explosives have important influences tbr environmental protection and national homeland security, in this review, a brief description of luminescent MOFs is presented, accompanied by a short comment on the four types of metal-based luminescent MOFs as sensing materials for nitro explosives detection. Then the trends and challenges of luminescent MOFs as sensing materials ibr nitro explosives are also prospected.