Synthesis,Crystal Structures,and Photoluminescence of Lanthanide Coordination Polymers with 4‐Acetamidobenzoate

The reactions of Ln(NO₃)₃ · 6H₂O and 4‐acetamidobenzoic acid (Haba) with 4,4′‐bipyridine (4,4′‐bpy) in ethanol solution resulted in three new lanthanide coordination polymers, namely {[Ln(aba)₃(H₂O)₂] · 0.5(4,4′‐bpy) · 2H₂O}_∞ [Ln = Sm ( 1 ), Gd ( 2 ), and Er ( 3 ), aba = 4‐acetamidobenzoate]. Compounds 1 – 3 are isomorphous and have one‐dimensional chains bridged by four aba anions. 4,4′‐Bipyridine molecules don’t take part in the coordination with Ln^III ions and occur in the lattice as guest molecules. Moreover, the adjacent 1D chains in the complex are further linked through numerous N–H ··· O and O–H ··· O hydrogen bonds to form a 3D supramolecular network. In addition, complex 1 in the solid state shows characteristic emission in the visible region at room temperature.     

Regioselective Photochemical Cycloaddition Reactions of Diolefinic Ligands in Coordination Polymers

The pure diolefinic ligand 1,4‐bis(pyridin‐4‐yl)‐1,3‐butadiene (bpbde) is photostable in the crystalline state. With the assistance of coordination‐driven metal‐organic assemblies, the photoreactivity of this diolefinic ligand can be significantly enhanced. A hydrothermal reaction of bpbde with Cd(NO₃)₂?4 H₂O and the auxiliary ligand adipic acid resulted in the formation of a two‐dimensional photoreactive coordination polymer (CP), [Cd(adipate)(bpbde)]_n ( 1 ). When the aliphatic carboxylic acid was replaced by pimelic acid, another photoreactive CP [Cd(pimelate)(bpbde)]_n ( 2 ) with a three‐dimensional framework was obtained. With irradiation of 365 nm UV light, the bpbde ligands in crystalline 1 and 2 underwent a regioselective photochemical [2+2] cycloaddition reaction and converted to 3,4,7,8‐tetra(pyridin‐4‐yl)tricyclo[4.2.0.0^2,5]octane (tptco) and 1,3‐bis(pyridin‐4‐yl)‐2,4‐bis(2‐(pyridin‐4‐yl)vinyl)cyclobutane (bpbpvcb), respectively. The results provide an interesting insight into the rational design of highly regio‐ or stereoselective photocatalytic reactions for the formation of special organic molecules.     

Dynamics and Proton Conduction of Heterogeneously Confined Imidazole in Porous Coordination Polymers

The nanoconfinement of proton carrier molecules may contribute to the lowing of their proton dissociation energy. However, the free proton transportation does not occur as easily as in liquid due to the restricted molecular motion from surface attraction. To resolve the puzzle, herein, imidazole is confined in the channels of porous coordination polymers with tunable geometries, and their electric/structural relaxations are quantified. Imidazole confined in a square-shape channels exhibits dynamics heterogeneity of core-shell-cylinder model. The core and shell layer possess faster and slower structural dynamics, respectively, when compared to the bulk imidazole. The dimensions and geometry of the nanochannels play an important role in both the shielding of the blocking effect from attractive surfaces and the frustration filling of the internal proton carrier molecules, ultimately contributing to the fast dynamics and enhanced proton conductivity.     

Three New Lanthanide Coordination Polymers Built from H2bpdc Ligands: Syntheses,Structures, and Properties

Three new lanthanide‐organic coordination polymers, {[Ln₂(bpdc)₂(H₂O)₆(NO₃)] · NO₃} [Ln = La ( 1 ), Ce ( 2 ), Pr ( 3 )] (H₂bpdc = 2, 2′‐bipyridine‐6, 6′‐dicarboxylic acid) were synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy as well as single‐crystal and powder X‐ray diffraction. Single‐crystal X‐ray diffraction analysis revealed that compounds 1 – 3 are isostructural, composed of two dimensional honeycomb network linked by bpdc ligands. The magnetic property of compound 3 was investigated.     

Solvent‐regulated Assembly of 1D and 2D CdII Coordination Polymers with Tetrafluorophthalate: Syntheses,Structures and Properties

Two new coordination polymers [Cd(1,2‐BDC‐F₄)(H₂O)₂(py)]_n ( 1 ) and {[Cd(1,2‐BDC‐F₄)(H₂O)₂](DMF)}_n ( 2 ) were prepared from the vapor diffusion reactions of Cd^II acetate with tetrafluorophthalic acid (1,2‐H₂BDC‐F₄) under different solvent atmospheres, and structurally characterized by single‐crystal diffraction technique. Both complexes reveal polymeric coordination architectures. Complex 1 is a one‐dimensional (1D) double chain, which crystallizes in the space group, P2₁2₁2₁. In 1 , each Cd^II ion is hexacoordinate by five oxygen atoms from two terminal water and three 1,2‐BDC‐F₄ anions with a μ₃‐bridging mode, as well as one nitrogen donor from one pyridine molecule. Complex 2 is a two‐dimensional (2D) layered network, which crystallizes in the P\bar{1} space group. In 2 , each Cd^II ion is heptacoordinate by seven oxygen atoms from two terminal water and four 1,2‐BDC‐F₄ anions with a μ₄‐bridging mode. The results clearly suggest that the judicious choice of solvent systems does play a critical role in the construction of coordination frameworks with distinct dimensionality and connectivity. Their spectroscopic, thermal, and fluorescence properties have also been investigated.     

Two New Lead(II) Coordination Polymers with (Substituted) Bipyridine and Auxiliary Nitrate Ligands

The reaction of lead(II) nitrate with 4,4′‐bipyridine (4,4′‐bpy) and 4,4′‐dimethyl‐2,2′‐bipyridine (4,4′‐dm‐2,2′‐bpy) or 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐dm‐2,2′‐bpy) resulted in the fomation of single crystals of [Pb₂(4,4′‐bpy)(5,5′‐dm‐2,2′‐bpy)₂(NO₃)₄] ( 1 ) and [Pb₃(4,4′‐bpy)₂(4,4′‐dm‐2,2′‐bpy)₂(NO₃)₆] ( 2 ). The new compounds have been characterized by single‐crystal X‐ray diffraction structure analysis as well as through elemental analysis, IR, ¹H‐NMR and ¹³C‐NMR spectroscopy and their stability has been studied by thermal analysis. In the crystal structure of ( 1 ) formula‐like dimers are further connected to a 2‐D network through the auxiliary nitrate ligands. The crystal structure of ( 2 ) exhibits two crystallographically independent Pb^II central atoms (in a ratio of 1:2). With the aid of the 4,4′‐bpy and the nitrate ions, a 3‐D polymeric structure is achieved.     

One‐dimensional Salen‐type Chain‐like Lanthanide(III) Coordination Polymers: Syntheses,Crystal Structures,and Fluorescence Properties

Four salen‐type lanthanide(III) coordination polymers [LnH₂L(NO₃)₃(MeOH)_x]_n [Ln = La ( 1 ), Ce ( 2 ), Sm ( 3 ), Gd ( 4 )] were prepared by reaction of Ln(NO₃)₃ · 6H₂O with H₂L [H₂L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine]. Single‐crystal X‐ray diffraction analysis revealed that H₂L effectively functions as a bridging ligand forming a series of 1D chain‐like polymers. The solid‐state fluorescence spectra of polymers 1 and 2 emit single ligand‐centered green fluorescence, whereas 3 exhibits typical red fluorescence of Sm^III ions. The lowest triplet level of ligand H₂L was calculated on the basis of the phosphorescence spectrum of Gd^III complex 4 . The energy transfer mechanisms in the lanthanide polymers were described and discussed.     

Synthesis,Characterization and Fluorescent Properties of Three One‐Dimensional Coordination Polymers Derived from Polypyridyl Ligands

Three one‐dimensional coordination polymers, [MnCl₂(4‐pyterpy)]∙2CHCl₃ ( 1 ), [Mn(NO₃)₂(4‐pyterpy)]∙CHCl₃ ( 2 ) and [Ag(NO₃)(3‐pyterpy)]∙H₂O ( 3 ) (4‐pyterpy = 4′‐(4‐pyridyl)‐2,2′:6′,2″‐terpyridine and 3‐pyterpy = 4′‐(3‐pyridyl)‐2,2′:6′,2″‐terpyridine) were synthesized and characterized by X‐ray diffraction. All three compounds exhibit a rare “head‐to‐tail” coordination of the multidentate ligand, but differ significantly in their polymer chain conformations. Additionally, the fluorescent properties of all three compounds were investigated and show a weak, ligand‐centered fluorescence at 416–418 nm.     

Coordination Chemistry of Lanthanides at “High” pH: Synthesis and Structure of the Pentadecanuclear Complex of Europium(III) with Tyrosine

A five-coordinate chloride ion is believed to template the assembly of a pentadecanuclear lanthanide complex of europium(III ). This cluster (see picture) has been prepared by coordination of europium(III ) perchlorate with tyrosine at about pH 6. Single crystal X-ray analysis established an unprecedented structure in which 15 constituent europium(III ) ions are organized into three parallel pentagonal layers.     

Two‐Dimensional and Three‐Dimensional Lanthanide Coordination Polymers Built from 4‐Hydroxypyridine‐2,6‐dicarboxylic Acid Ligand

4‐Hydroxypyridine‐2,6‐dicarboxylic acid (H₃CAM) reacts with Ln₂O₃(Ln = La, Ce) or Ln(NO₃)₃ (Ln = Sm, Dy, Gd, Ho) in hydrothermal reactions to form a series of lanthanide coordination polymers 1 – 6 . Elemental analysis, IR spectra and X‐ray crystal structure analysis were carried out to determine the composition and crystal structure of 1 – 6 . Compounds 1 and 2 are isostructural and contain tetranuclear metallic ring unit and 3D framework. 4 – 6 are isostructural contain 2D network. Furthermore, the photoluminescent properties of 3 and 4 at room temperature were also studied.     

Coordination Polymers with Different Dimensionalities: from 2D Layer to 3D Framework

Two coordination polymers, namely [Cd(HL)₂]_n · nH₂O ( 1 ) and [Zn(L)]_n ( 2 ) (H₂L = benzimidazole‐2‐butanoic acid), were prepared by solvothermal reaction of Cd(NO₃)₂ or Zn(NO₃)₂ and H₂L. The structures of these two compounds were determined by the single‐crystal X‐ray diffraction analyses and further characterized by IR spectroscopy, elemental analyses, powder X‐ray diffraction analyses, and thermal analyses. Compound 1 is a two‐dimensional (2D) layer framework, which is further packed into a 3D supramolecular framework by intermolecular hydrogen bonds, whereas compound 2 is a three‐dimensional (3D) framework with 3‐connected etb topology. The H₂L ligand in compounds 1 and 2 displays two different anionic forms (HL^– and L^2–), which then adopt two different coordination modes. Moreover, thermal stabilities and luminescent properties of these two compounds were also investigated.     

Coordination Polymers based on the Neutral Ditopic Ligand (C6H4PO(OCH3)2)2 Involving some f‐Block Elements

An improved synthesis using microwave heating affords (C₆H₄PO(OCH₃)₂)₂ in excellent isolated yield (95 %). The ligand properties of this bisphosphonateester were explored towards hard metal centers M²⁺ (M = Ca, UO₂) and M³⁺ (M = La, Ce, Sm, Eu) resulting in coordination polymers, for which the reduction of ionic size of the central metal atom resulted in lower‐dimensional structural motifs as opposed to higher dimensional networks obtained for the larger ions. All coordination polymers were characterized by single‐crystal X‐ray diffraction, IR spectroscopy, and combustion analysis. The ligand was furthermore characterized with multinuclear NMR spectroscopy.     

Non‐centrosymmetric CuSCN Based Coordination Polymers with Substituted Pyrazine and Pyrimidine Ligands

Non‐centrosymmetric one‐ to three‐dimensional CuSCN‐based coordination polymers with substituted pyrazine or pyrimidine spacer ligands can be prepared by self‐assembly in acetonitrile solution at 100 °C. Both [CuSCN(2 NCpyz)₂] ( 1 ) (2 NCpyz = 2‐cyanopyrazine) and [CuSCN(4 HOpym)₂] ( 3 ) (4 HOpym = 4‐hydroxypyrimidine) contain single zigzag CuSCN chains as their central backbone and crystallise in polar space groups (monoclinic Cm and orthorhombic Ama2). In [(CuSCN)₂(μ‐2 Mepyz)] ( 2 ) (2 Mepyz = 2‐methylpyrazine), [(CuSCN)₂] staircase double chains are connected by bridging 2 Mepyz ligands to afford a lamellar polymer (triclinic P 1). Whereas [CuSCN(5 Brpym)] ( 4 ) (5 Brpym = 5‐bromopyrimidine) with its honeycomb [CuSCN] layers is chiral (monoclinic P2₁), both 3 D polymers [(CuSCN)₂(μ‐pym)] ( 5 ) and [(CuSCN)₃(μ‐4 Mepym)] ( 6 ) (4 Mepym = 4‐methylpyrimidine) contain polar coordination networks (orthorhombic Fdd2 and monoclinic Pc). The CuSCN framework in ( 5 ) consists of thiocyanate bridged [CuS] chains, that in 6 of interlocked [CuSCN] and [Cu₂S(SCN)] sheets.     

N,N′‐Bis(Salicylidene)‐1,2‐Cyclohexanediamine Lanthanide(III) Coordination Polymers: Syntheses,Crystal Structures,and Luminescence Properties

The salen‐type ligand H₂L [H₂L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine] was utilized for the synthesis of two lanthanide(III) coordination polymers [LnH₂L(NO₃)₃MeOH]_n [Ln = Eu ( 1 ) and Ln = Lu ( 2 )]. The single‐crystal X‐ray diffraction analyses of 1 and 2 revealed that they are isomorphous and exhibit one‐dimension neutral structure, in which H₂L effectively functions as a bridging ligand and give rise to a chain‐like polymer. The luminescent properties of polymers in solid state and in solution were investigated and 1 exhibits typical red luminescence of Eu^III ions in solid state and dichloromethane solution and 2 emits the ligand‐centered blue luminescence. The energy transfer mechanisms in these luminescent lanthanide polymers were described through calculation of the lowest triplet level of ligand H₂L.     

Syntheses,Structures, and Photoluminescence of Lanthanide Coordination Polymers Based on 4‐Oxo‐1,4‐dihydro‐2,6‐pyridinedicarboxylic acid

Investigating the coordination chemistry of H₂CDA (4‐oxo‐1,4‐dihydro‐2,6‐pyridinedicarboxylic acid) with rare earth salts Ln(NO₃)₃ under hydrothermal conditions, structure transformation phenomenon was observed. The ligand, H₂CDA charged to its position isomer, enol type structure, H₃CAM (4‐hydroxypyridine‐2,6‐dicarboxylic acid). Six new lanthanide(III) coordination polymers with the formulas [Ln(CAM)(H₂O)₃]_n [Ln = La ( 1 ), Pr, ( 2 )] and {[Ln(CAM)(H₂O)₃] · H₂O}_n [Ln = Nd, ( 3 ), Sm, ( 4 ), Eu, ( 5 ), Y, ( 6 )] were synthesized and characterized. The X‐ray structure analyses show two kinds of coordination structures. The complexes 1 and 2 and 3 – 6 are isostructural. Complexes 1 and 2 crystallize in the monoclinic C₂/c space group, whereas 3 – 6 crystallize in the monoclinic system with space group P2₁/n. In the two kinds of structures, H₃CAM displays two different coordination modes. The Sm^III and Eu^III complexes exhibit the corresponding characteristic luminescence in the visible region at an excitation of 376 nm.     

Assembly of Chiral Two- and Three-dimensional Copper(I) Pseudohalide Based Coordination Polymers with Asymmetrically Substituted Pyrazine and Pyrimidine Ligands

The coordination polymers [(CuCN)₂(μ-2 Mepyz)], [CuCN(μ-2 Mepyz)] and [CuCN(μ-4 Mepym)] ( 1 – 3 ) (2 Mepyz = 2-methylpyrazine; 4 Mepym = 4-methylpyrimidine) may be prepared by self-assembly in acetonitrile solution at 100 °C ( 1 , 3 ) or without solvent at 20 °C ( 2 ). All three contain [CuCN] chains that are bridged by the bidentate aromatic ligands into sheets in 1 and 3 D frameworks in 2 and 3 . Reaction of CuSCN with these heterocyclic diazines at 100 °C leads to formation of the lamellar coordination polymers [(CuSCN)(μ-2 Mepyz)] ( 4 ) and [CuSCN · (4 Mepym-κN1)] ( 5 ), which contain respectively [CuSCN] chains and trans-trans fused [CuSCN] sheets as substructures. The presence of an asymmetric substitution pattern in 2 Mepyz and 4 Mepym induces the adoption of a chiral structure by 2 and 5 (space groups P2₁2₁2₁ and P1).     

Synthesis and Crystal Structure of Novel Coordination Polymers with Nitrilotripropionic Acid

A novel three‐dimensional (3D) lanthanide‐organic framework [Pr₃(NTP)₃(H₂O)₆] · 10H₂O ( 1 ), (H₃NTP = 3,3′,3′‐nitrilotripropionic acid) was synthesized and characterized by elemental analyses, IR spectroscopy, and X‐ray diffraction analyses. The results show that complex 1 is connected through NTP ligands to form a 3D network with microchannels. The coordination mode of the NTP ligand was found for the first time. In order to investigate the temperature effects on controlling the dimensionality of the complexes, another two complexes, namely, [Nd(NTP)(H₂O)₂] · H₂O · HBr ( 2 ) and [Pr(H₂O)][⁺NH₃(CH₂CH₂COO^–)][OOCCOO]_1.5 ( 3 ) were synthesized and characterized. Notably, in complex 3 , the NTP ligand lost its two arms because of the high temperature. Furthermore, the thermogravimetric analyses of the three complexes are discussed in detail.     

Complexation of 1,4‐Bis(phenylthio)butane on Mercury(II) Salts: Formation of Extended 2D Coordination Polymers

Two novel two‐dimensional (2D) coordination polymers of stoichiometry [{PhS(CH₂)₄SPh}Hg₂X₄]_n (X = Cl, 2a ; X = Br, 2b ) have been prepared by treatment of HgX₂ with PhS(CH₂)₄SPh 1 , acting as bridging dithioether ligand. The extended 2D structures result from bridging coordination of 1 between two mercury atoms and intermolecular Hg–X interactions, thus linking the HgX₂ units in two dimensions. As established for 2a,b by single‐crystal X‐ray diffraction, the coordination around the Hg centers in both isomorphous compounds (monoclinic, space group P2₁/c) is distorted tetrahedral, with quite short Hg‐thioether bonds of 2.4780(19) ( 2a ) and 2.499(3) Å ( 2b ), respectively.     

Mathematical Correction for Polyatomic Isobaric Spectral Interferences in Determination of Lanthanides by Inductively Coupled Plasma Mass Spectrometry

The determination of lanthanides by Inductively Coupled Plasma Mass Spectrometry (ICP‐MS) is complicated by several spectral overlaps from M⁺, MO⁺ or MOH⁺ ions formed in the ICP. Especially, it is essential to avoid the spectral interferences from lighter lanthanide and Ba polyatomic ions on middle or heavier lanthanides. To tackle this problem, we have developed a mathematical correction method, which reduces all the spectral overlaps from oxide species of Pr, Nd, Ce and Sm over Gd, Tb, Dy and Ho, and Gd, Tb over Yb and Lu. It can also successfully correct the oxide and hydroxide interference of Ba over Eu. The effectiveness of the proposed the mathematical correction scheme is demonstrated for the USGS Standard Rock samples AGV‐1 and G‐2. The results show that the experimental data obtained by applying the mathematical correction scheme for lanthanides is in good agreement with the reported values, using pneumatic and ultrasonic nebulisation methods, for their ICP‐MS analysis.     

Syntheses and Characterization of Two Coordination Polymers Constructed by the Ligand 3,5‐Bis(pyridin‐4‐ylmethoxy)benzoic Acid

Two coordination polymers, namely [Zn(L1)(OAc)]·H₂O ( 1 ) and [Cd(L1)₂] ( 2 ), where L1 = 3,5‐bis(pyridin‐4‐ylmethoxy)benzoic acid, have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction analysis. Complex 1 has a 2D layer structure in which the hydrogen bonds between lattice water molecules and uncoordinated carboxylate oxygen atoms of the ligand L1 in the adjacent layers extend the 2D layer into a 3D supramolecular architecture. The structure of 2 is a 2D (3,5)‐connected net with (3·5²)(3²·5³·6⁴·7) topology. In addition, the luminescent properties of complexes 1 and 2 have been studied in the solid state at room temperature.