Four New Cd(II) Coordination Polymers with Mixed Multidentate N‑Donors and Biphenyl-Based Polycarboxylate Ligands: Syntheses, Structures, and Photoluminescent Properties

Four new cadmium­(II) coordination polymers (CPs), {[Cd­(Hpptpd)­(H2bptta)]·8H2O}n (1), {[Cd2(Hpptpd)2(bptta)­(H2O)2]·4H2O}n (2), {[Cd2(pptpz)­(bpta)­(H2O)]·H2O}n (3), and {[Cd­(Hpptpz)­(bpba)]·2H2O}n (4) (Hpptpd = 2-(3-(4-(pyridin-4-yl)­phenyl)-1H-1,2,4-triazol-5-yl)­pyridine, Hpptpz = 2-(3-(4-(pyridin-4-yl)­phenyl)-1H-1,2,4-triazol-5-yl)­pyrazine, H4bptta = 3,3′,5,5′-biphenyltetracarboxylic acid, H3bpta = 3,4′,5-biphenyltricarboxylic acid, H2bpba = 3,4′-biphenylbicarboxylic acid), were synthesized under hydrothermal conditions. The CPs were structurally characterized by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complex 1 exhibits an unusual 2D + 2D → 2D parallel interpenetrated 63-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting three-dimensional (3D) supramolecular architecture through the interbilayer π···π stacking between Hpptpd ligands and nonclassical C–H···O hydrogen bonds. Complex 2 is a one-dimensional (1D) molecular ladder along the a direction and further extended via hydrogen bonds into the 3D supramolecular framework. Complex 3 exhibits a novel complicated 3D (3,4,4,5)-connected framework with the Schläfli symbol of (4·65)­(4·67·82)­(63)­(64·82). Complex 4 manifests an intriguing layered structure with 5-connected cadmium atom as a unique node and can be simplified to an Archimedean (33·44·53) cem topology with triangular and rectangular circuits. The topology of 4 could be alternately simplified to a 3,4-connected binodal layer with a V2O5-type network. The thermal stabilities and photoluminescence behaviors of them were also discussed

Four New Cd(II) Coordination Polymers with Mixed Multidentate N‑Donors and Biphenyl-Based Polycarboxylate Ligands: Syntheses, Structures, and Photoluminescent Properties

Four new cadmium­(II) coordination polymers (CPs), {[Cd­(Hpptpd)­(H₂bptta)]·8H₂O}_<i>n</i> (<b>1</b>), {[Cd₂(Hpptpd)₂(bptta)­(H₂O)₂]·4H₂O}_<i>n</i> (<b>2</b>), {[Cd₂(pptpz)­(bpta)­(H₂O)]·H₂O}<i>_n</i> (<b>3</b>), and {[Cd­(Hpptpz)­(bpba)]·2H₂O}_<i>n</i> (<b>4</b>) (Hpptpd = 2-(3-(4-(pyridin-4-yl)­phenyl)-1<i>H</i>-1,2,4-triazol-5-yl)­pyridine, Hpptpz = 2-(3-(4-(pyridin-4-yl)­phenyl)-1<i>H</i>-1,2,4-triazol-5-yl)­pyrazine, H₄bptta = 3,3′,5,5′-biphenyltetracarboxylic acid, H₃bpta = 3,4′,5-biphenyltricarboxylic acid, H₂bpba = 3,4′-biphenylbicarboxylic acid), were synthesized under hydrothermal conditions. The CPs were structurally characterized by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complex <b>1</b> exhibits an unusual 2D + 2D → 2D parallel interpenetrated 6³-<b>hcb</b> network. The adjacent 2D networks are interdigitated with each other to form the resulting three-dimensional (3D) supramolecular architecture through the interbilayer π···π stacking between Hpptpd ligands and nonclassical C–H···O hydrogen bonds. Complex <b>2</b> is a one-dimensional (1D) molecular ladder along the <i>a</i> direction and further extended via hydrogen bonds into the 3D supramolecular framework. Complex <b>3</b> exhibits a novel complicated 3D (3,4,4,5)-connected framework with the Schläfli symbol of (4·6⁵)­(4·6⁷·8²)­(6³)­(6⁴·8²). Complex <b>4</b> manifests an intriguing layered structure with 5-connected cadmium atom as a unique node and can be simplified to an Archimedean (3³·4⁴·5³) <b>cem</b> topology with triangular and rectangular circuits. The topology of <b>4</b> could be alternately simplified to a 3,4-connected binodal layer with a V₂O₅-type network. The thermal stabilities and photoluminescence behaviors of them were also discussed

Near-Infrared Emitters: Stepwise Assembly of Two Heteropolynuclear Clusters with Tunable Ag^I:Zn^II Ratio

Two 3d–4d heteropolynuclear clusters with Ag–Zn ratios of 9:2 and 9:4 were stepwise constructed from a robust nonanuclear silver cluster. Their crystal structures consist of a common bucket-shaped [Ag₉(mba)₉]^9– (H₂mba = 2-mercaptobenzoic acid) core with different numbers of Zn^II connected by different <i>exo</i>-oriented carboxylates. Most fascinating is the observation of emission (∼703 nm) in the near-infrared (NIR) region at 300 K that may be compared to the related Ag₉Zn₃ cluster with aliphatic polyamine as auxiliary ligand that emits from the visible (∼580 nm). The shift is associated with the change of ligand field of the 2,2′-bipyridine. The emission intensity and lifetime were dramatically enhanced along with the slight bathochromic shift upon cooling from 300 K to 80 K. The results raise two significant issues: (a) the structural and electronic effects of the secondary metal binding to the metalloligand and the factors influencing the heteropolynuclear cluster assembly and (b) the use of NIR fluorescence, introduced by integrating two luminophores into one heteropolynuclear entity, in detecting free-moving zinc in biological systems both in vivo and in vitro

Hierarchical Assembly of a {Mn^II₁₅Mn^III₄} Brucite Disc: Step-by-Step Formation and Ferrimagnetism

In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn₇) to nonadecamer (Mn₁₉) satisfying the relation 1 + Σ_<i>n</i>6<i>n</i>, where <i>n</i> is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn₁₀, Mn₁₂, and Mn₁₄, were identified. Furthermore, the Mn₁₉ disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn₁₉­(<i>L</i>)_<i>x</i>­(OH)_<i>y</i>­(N₃)_{36–<i>x</i>−<i>y</i>}]²⁺ (<i>x</i> = 18, 17, 16; <i>y</i> = 8, 7, 6; H<i>L</i> = 1-(hydroxy­methyl)-3,5-dimethylpyrazole) indicating progressive exchange of N₃^– for OH^–. The high symmetry (<i>R</i>-3) Mn₁₉ crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn^II₁₅Mn^III₄]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH₃CN. The moment of nearly 50 Nμ_B suggests Mn^II–Mn^II and Mn^III–Mn^III are ferromagnetically coupled while Mn^II–Mn^III is antiferromagnetic which is likely if the Mn^III are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules

Hierarchical Assembly of a {Mn^II₁₅Mn^III₄} Brucite Disc: Step-by-Step Formation and Ferrimagnetism

In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn₇) to nonadecamer (Mn₁₉) satisfying the relation 1 + Σ_<i>n</i>6<i>n</i>, where <i>n</i> is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn₁₀, Mn₁₂, and Mn₁₄, were identified. Furthermore, the Mn₁₉ disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn₁₉­(<i>L</i>)_<i>x</i>­(OH)_<i>y</i>­(N₃)_{36–<i>x</i>−<i>y</i>}]²⁺ (<i>x</i> = 18, 17, 16; <i>y</i> = 8, 7, 6; H<i>L</i> = 1-(hydroxy­methyl)-3,5-dimethylpyrazole) indicating progressive exchange of N₃^– for OH^–. The high symmetry (<i>R</i>-3) Mn₁₉ crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn^II₁₅Mn^III₄]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH₃CN. The moment of nearly 50 Nμ_B suggests Mn^II–Mn^II and Mn^III–Mn^III are ferromagnetically coupled while Mn^II–Mn^III is antiferromagnetic which is likely if the Mn^III are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules