Host-Guest Recognition-Mediated Supramolecular Aggregation-Induced Electrochemiluminescence of Iridium(III) Complexes for Nucleic Acid Bioassay.

Currently reported aggregation-induced electroluminescence (AIECL) is usually based on the electrostatic integration of luminous monomers, and its application is still limited by the low ECL efficiency and poor structural stability of electrostatic integration-based AIECL emitters. Herein, host-guest recognition-mediated supramolecular AIECL was creatively developed to overcome the defects of electrostatic-integration-based AIECL. Cucurbit[8]uril (CB[8]) as the host recognized tris (2-phenylpyridine) iridium(III) [Ir(ppy)3] as the guest to form a novel supramolecular complex Ir-CB[8]. CB[8] can not only provide a large hydrophobic cavity to efficiently load Ir(ppy)3 and enrich coreactant tripropylamine but also utilize its carbonyl-laced portals to form intramolecular hydrogen bonds to stabilize the supramolecular structure, so Ir-CB[8] revealed excellent AIECL performance. The AIECL emitter Ir-CB[8] coupled the efficient DNA walker to construct a sensing system for miRNA-16 detection. Au nanoparticles@norepinephrine (AuNPs@NE) trapped by single-strand S1 was developed to significantly quench the ECL emission of Ir-CB[8]. When the target microRNA-16 (miRNA-16) existed, H1 was opened and the sequential assembly from H2 to H7 was triggered, forming "windmill"-like DNA walker with six Pb2+-dependent leg DNA. The assembled DNA walker, which was centered on DNA structure, had high efficiency and biocompatibility and can cut S1 to keep the DNA fragment-carrying quencher AuNPs@NE away from the electrode surface, thus restoring the ECL emission of Ir-CB[8] and realizing ultrasensitive detection of miRNA-16. Supramolecular AIECL mediated by host-guest recognition provides a new way for constructing AIECL emitters with excellent structural stability and AIECL efficiency, and an Ir-CB[8] coupling "windmill"-like DNA walker builds a promising ECL-sensing system for bioassay.

Calixarene-Based {Ni18} Coordination Wheel: Highly Efficient Electrocatalyst for the Glucose Oxidation and Template for the Homogenous Cluster Fabrication.

Catalyst plays a very important role in the exploration of new energy. To obtain a highly efficient electrocatalyst for the glucose oxidation and tiny metal nanocluster catalysts, a calixarene-based {Ni18} coordination wheel with sulfur atoms on the cavity surface was designed, synthesized, and used as the porous template. Contributing from the active sites of nickel cations, the as-synthesized coordination wheels can efficiently catalyze the electrochemical oxidation of glucose with the onset and peak potentials of 0.3 and 0.46 V in alkaline medium, and the catalysis does not depend on the atmosphere (N2, air, or O2), which indicates that the coordination wheel will be a promising electrocatalyst candidate for the compartmentless glucose-air fuel cell. Meanwhile, benefiting from its confined cavity and inner sulfur surface, such a coordination wheel can serve as a general template for the fabrication and encapsulation of tiny metal nanoclusters of Au, Pd, Ir, Ru, Rh, Pt, and AuPd. In electrochemical examinations, the bimetallic AuPd clusters confined in the coordination wheel show higher current density than commercial Pt/C toward hydrogen evolution reaction (HER). The present study shows that the designed coordination wheel can be used as not only a type of novel catalyst itself but also a class of templates for metal cluster catalysts.

Ultrafine Pt Nanoclusters Confined in a Calixarene-Based {Ni24} Coordination Cage for High-Efficient Hydrogen Evolution Reaction.

To obtain stable and ultrafine Pt nanoclusters, a trigonal prismatic coordination cage with the sulfur atoms on the edges was solvothermally synthesized to confine them. In the structure of {Ni24(TC4A-SO2)6(TDC)12 (H2O)6} (H4TC4A-SO2 = p-tert-butylsulfonylcalix[4]arene; H2TDC = 2,5-thiophenedicarboxylic acid), three Ni4-(TC4A-SO2) SBUs are bridged by three TDC ligands into a triangle and two such triangles are pillared by three pairs of TDC ligands to form a trigonal prism. The cage cavity has 12 sulfur atoms on the surface. Because of the porous structure and strong covalent interaction between metal and sulfur, ultrafine Pt nanoclusters composed of less than ∼18 Pt atoms can be facilely confined in the present trigonal prismatic cage (Pt@CIAC-121). The as-synthesized Pt NCs exhibit higher electrocatalytic activity than commercial Pt/C toward hydrogen evolution reaction.

Discrete {Ni40} Coordination Cage: A Calixarene-Based Johnson-Type (J17) Hexadecahedron.

We report a Johnson hexadecahedronal coordination cage, constructed via 10 Ni4-p-tert-butylthiacalix[4]arene (Ni4-TC4A) units as vertices and 16 5-(pyridin-4-yl)isophthalate (PIP) ligands as tiles. It features a gyroelongated square bipyramidal geometry, equivalent to two square pyramids pillared by a square antiprism, a J17 Johnson solid. Remarkably, the cage compound exhibits a much higher uptake capacity of C3H8 than CH4, representing a promising material for separation of these two gases. In contrast, Co4-TC4A units are linked by PIP ligands and rare {Co4O4Cl2} clusters, providing a one-dimensional bamboo stick-like polymer.

3-Carb-oxy-quinolin-1-ium-2-carboxyl-ate monohydrate.

The title compound, C(11)H(7)NO(4)·H(2)O, contains a 3-carb-oxy-quinolin-1-ium-2-carboxyl-ate (qda) zwitterion and one water mol-ecule. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers, and these dimers are further connected by O-H⋯O hydrogen bonds into a three-dimensional supra-molecular architecture. In addition, π-π inter-actions occur between pyridine and benzene rings from different qda ligands [centroid-centroid distance = 3.749 (1) Å] and the dihedral angles of the -CO(2)H and -CO(2) groups to the quinoline system are 8.47 (3) and 88.16 (6)°, respectively.

2,2'-Dimethyl-1,1'-[2,2-bis-(bromo-methyl)propane-1,3-di-yl]dibenzimidazole hemihydrate.

The title compound, C(21)H(22)Br(2)N(4)·0.5H(2)O, contains two benzimidazole groups which may provide two potential coordination nodes for the construction of metal-organic frameworks. The mean planes of the two imidazole groups are almost perpendicular, with a dihedral angle of 83.05 (2)°, and adjacent mol-ecules are linked into a one-dimensional chain by π-π stacking inter-actions between imidazole groups of different mol-ecules [centroid-to-centroid distances of 3.834 (2) and 3.522 (2) Å].

Bis(1,10-phenanthroline-5,6-dione-κN,N')silver(I) 2-hy-droxy-3,5-dinitro-benzoate.

In the cation of the title salt, [Ag(C(12)H(6)N(2)O(2))(2)](C(7)H(3)N(2)O(7)), the Ag(I) atom is coordinated in a distorted tetra-hedral geometry by four N atoms from two 1,10-phenanthroline-5,6-dione ligands, while the 3,5-dinitro-salicylate anion has only a short contact [2.847 (6) Å] between one of its O atoms and the Ag(I) atom. The dihedral angle between the two 1,10-phenanthroline-5,6-dione ligands is 58.4 (1)°. There is an intra-molecular O-H⋯O hydrogen bond in the 3,5-dinitro-salicylate anion.

2,4,5-Tris(pyridin-4-yl)-1H-imidazole monohydrate.

In the crystal structure of the title compound, C(18)H(13)N(5)·H(2)O, adjacent mol-ecules are linked by O-H⋯N and N-H⋯O hydrogen bonds, generating a chain propagating along [001].

Poly[[tri-µ(3)-hydroxido-tris-(µ(4)-pyridine-2,5-dicarboxyl-ato)trineodymium(III)] monohydrate].

In the title compound, {[Nd(3)(C(7)H(3)NO(4))(3)(OH)(3)]·H(2)O}(n), the Nd(III) atom is eight-coordinated by the three O atoms of three asymmetrically µ(3)-bridging hydroxide groups, by four carboxyl-ate O atoms of four different pyridine-2,5-dicarboxyl-ate (2,5-pydc) ligands, and by the N atom of a 2,5-pydc ligand. Six Nd atoms are connected by six hydroxide groups, forming an [Nd(6)(µ(3)-OH)(6)] cluster unit of symmetry -3 and a slightly compressed octa-hedral geometry. Adjacent [Nd(6)(µ(3)-OH)(6)] clusters are connected by the 2,5-pydc ligands, via O and N atoms, forming chains along the c axis. The remaining O atoms of the 2,5-pydc ligands link these chains into a three-dimensional framework. A disordered water molecule, located on a threefold rotation axis at the opposite side of the [Nd(6)(µ(3)-OH)(6)] cluster and exposed to each of the three Nd atoms, completes the structure.

cyclo-Tetra-kis{µ-2,2'-dimethyl-1,1'-[2,2-bis-(bromo-meth-yl)propane-1,3-di-yl]di(1H-benzimidazole)-κN:N}tetra-kis-[bromidocopper(I)].

The title compound, [Cu(4)Br(4)(C(21)H(22)Br(2)N(4))(4)], features a macrocyclic Cu(4)L(4) ring system in which each Cu(I) atom is coordinated by one bromide ion and two N atoms from two 2,2'-dimethyl-1,1'-[2,2-bis-(bromo-meth-yl)propane-1,3-di-yl]di(1H-benzimidazole) (L) ligands in a distorted trigonal-planar geometry. The L ligands adopt either a cis or trans configuration. The asymmetric unit contains one half-mol-ecule with the center of the macrocycle located on a crystallographic center of inversion. Each bromide ion binds to a Cu(I) atom in a terminal mode and is oriented outside the ring. The macrocycles are inter-connected into a two-dimensional network by π-π inter-actions between benzimid-azole groups from different rings [centroid-centroid distance = 3.803 (5) Å.

Poly[(µ(2)-quinoline-3-carboxyl-ato-κN:O)(µ(2)-quinoline-3-carboxyl-ato-κN:O,O')cadmium].

In the title compound, [Cd(C(10)H(6)NO(2))(2)](n), the Cd(II) atom is coordinated by three O atoms and two N atoms from four quinoline-3-carboxyl-ate (L(-)) ligands, leading to a distorted trigonal-bipyramidal geometry. The L(-) ligands link the Cd(II) atoms into a plane parallel to (100), with one ligand being tridentate, coordinating via the N atom and chelating a second Cd atom, and the other being bidentate, bridging two Cd atoms via the N and one O atom.. This two-dimensional network extends into a double-layer network by π-π inter-actions, with centroid-centroid distances of 3.680 (2) and 3.752 (2) Å. Another type of π-π inter-action between pyridine rings [centroid-centroid distance = 3.527 (2) Å] leads to a three-dimensional supra-molecular architecture.

A coordination cage hosting ultrafine and highly catalytically active gold nanoparticles.

Ultrafine metal nanoparticles (MNPs) with size <2 nm are of great interest due to their superior catalytic capabilities. Herein, we report the size-controlled synthesis of gold nanoparticles (Au NPs) by using a thiacalixarene-based coordination cage CIAC-108 as a confined host or stabilizer. The Au NPs encapsulated within the cavity of CIAC-108 (Au@CIAC-108) show smaller size (∼1.3 nm) than the ones (∼4.7 nm) anchored on the surface of CIAC-108 (Au/CIAC-108). The cage-embedded Au NPs can be used as a homogeneous catalyst in a mixture of methanol and dichloromethane while as a heterogeneous catalyst in methanol. The homogeneous catalyst Au@CIAC-108-homo exhibits significantly enhanced catalytic activities toward nitroarene reduction and organic dye decomposition, as compared with its larger counterpart Au/CIAC-108-homo and its heterogeneous counterpart Au@CIAC-108-hetero. More importantly, the as-prepared Au@CIAC-108-homo possesses remarkable stability and durability.

Poly[[diaqua-bis-(µ(3)-3-carboxyl-ato-4-hy-droxy-benzene-sulfonato)-tri-µ(2)-pyrazine-tetra-silver(I)] dihydrate].

The title coordination polymer, {[Ag(4)(C(7)H(4)O(6)S)(2)(C(4)H(4)N(2))(3)(H(2)O)(2)]·2H(2)O}(n), contains two independent Ag(I) ions. One Ag(I) ion is coordinated by one O atom from a 3-carboxyl-ato-4-hy-droxy-benzene-sulfonate (L) ligand, two N atoms from two pyrazine ligands and a water mol-ecule. The other Ag(I) ion is coordinated by two O atoms from two L ligands and one N atom from a pyrazine ligand. One of the pyrazine ligands lies on an inversion center. The L and pyrazine ligands link the Ag(I) ions into polymeric layers parallel to the ac plane. The layers are connected by inter-molecular O-H⋯O hydrogen bonds. An intra-molecular O-H⋯O hydrogen bond is also present in the L ligand.

Organoamine-induced isomerism of calixarene-based complexes: from 1D to 2D.

Two isomers of the calixarene-based cobalt complex [Co4Cl(TC4A)(BCPT)2]- (H4TC4A = p-tert-butylthiacalix[4]arene; H2BCPT = 3,5-bis (4'-carboxy-phenyl)-1,2,4-triazole) were obtained under the solvothermal conditions with tetramethylammonium/tetraethylammonium hydroxide (CIAC-236) and triethylamine (CIAC-237). Single crystal X-ray diffraction reveals that CIAC-236 has a 1D zigzag aggregate constructed by bridging the shuttlecock-like Co4-TC4A secondary building units (SBUs) with two pairs of opposite V-shaped BCPT ligands while CIAC-237 possesses a 2D layer assembly with each Co4-TC4A SBU bonded by four BCPT ligands in a same direction (clockwise or counterclockwise), which indicates that different shapes of the organoamines lead to different assembly of the BCPT ligands and the formation of different extended aggregates. For comparison, only the 1D structure ([Fe4Cl(TC4A)](BCPT)2]-, CIAC-238) was obtained for the iron complexes with all these three organoamines, which would be attributed to different property and coordination of iron element. Magnetic properties of all these three compounds were studied.

A metal-calixarene coordination nanotube with 5-(pyrimidin-5-yl)isophthalic acid.

A metal-organic nanotube (MONT) was assembled by bridging the truncated metal-calixarene octahedra with coordinating water molecules. Remarkably, the tubular compound exhibited a much higher sorption capacity for C2H6 and C3H8 than for CH4, and hence represents a promising material for separating these gases. The addition of a little NiSO4 into the reaction system led to the formation of a 2D metal-calixarene network.

A tetragonal prismatic {Co32} nanocage based on thiacalixarene.

A novel coordination nanocage was obtained with in situ-generated tetrazole ligands from the cobalt-thiacalix[4]arene system. Four in situ-generated 1,3-bis(2H-tetrazol-5-yl)benzene ligands bolster eight Co4-calix shuttle-cock-like secondary building units (SBUs) into a hollow tetragonal prism with a high surface area. The unprecedented {Co32} nanocage presents the highest nuclearity example.