A Review of Crystalline Multibridged Cyclophane Cages: Synthesis, Their Conformational Behavior, and Properties.

This paper reviews the most stable conformation of crystalline three-dimensional cyclophane (CP) achieved by self-assembling based on changing the type of aromatic compound or regulating the type and number of bridging groups. [3n]cyclophanes (CPs) were reported to form supramolecular compounds with bind organic, inorganic anions, or neutral molecules selectively. [3n]cyclophanes ([3n]CPs) have stronger donor capability relative to compound [2n]cyclophanes ([2n]CPs), and it is expected to be a new type of electron donor for the progress of fresh electron conductive materials. The synthesis, conformational behavior, and properties of crystalline multi-bridge rings are summarized and discussed.

Multiple Responsive CPL Switches in an Enantiomeric Pair of Perovskite Confined in Lanthanide MOFs.

Circularly polarized luminescence (CPL) switches have attracted widespread attention due to their potential applications in advanced information technologies. However, the design and fabrication of solid-state multiple-responsive CPL switches remain challenging. Here, through self-assembly of chiral metal-organic frameworks (MOFs) and perovskite nanocrystals (NCs), a pair of crystalline enantiomeric (P)-(+)/(M)-(-)-EuMOF⊃MAPbX3 (MA = CH3 NH3 + , X = Cl- , Br- , I- ) adducts is prepared, where the achiral MAPbBr3 perovskite NCs embedded into chiral MOFs inherit the chirality of host MOFs by host-guest EuBr and PbO coordination bonds, which is demonstrated by synchrotron-radiation-based X-ray absorption spectroscopy. The chiral adducts show enhanced photoluminescence quantum yield (PLQY), good thermal stability of CPL in air, and photoswitchable CPL properties upon altering different UV irradiation. Based on two chiral emission centers and their different characteristics, reversible CPL switches are realized upon a diversity of external stimuli, for example, chemicals (water /CH3 NH3 Br solution) or temperatures (room temperature/high temperature). Benefiting from the extraordinary stimuli-responsive and highly reversible switchable CPL, multiple information encryptions and decryptions integrated with CPL, together with a chiroptical logic gate are successfully designed. This work opens a new avenue to generally fabricate solid-state CPL composite materials and develops new applications based on switchable CPL.

Intermolecular interactions, photocatalysis and THz-TDS interrelationships for lanthanide phosphine oxide complexes based on {PW12}.

A series of rare earth complexes containing (α-PW12O40)3- and PO ligand are synthesized by water bath in 70 °C, [Ln(OPPh3)4(H2O)3](PW12O40)·4CH3CN (Ln = La, Pr, Nd, Sm, Gd, Tb, Ho 1-7) (OPPh3 = Triphenylphosphine oxide, {PW12} = phosphotungstic acid). The precise structures are confirmed by X-ray single crystal diffraction and the result shows all complexes are isostructural. Complexes 1-7 are fully characterized by PXRD, FT-IR, TGA, UV diffuse reflectance spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 3 exhibits the highest photocatalytic degradation efficiency for methylene blue (MB) in this series of complexes. The experimental results showed that the photodegradation efficiency can remain constant at the level of 95% after five consecutive cycles. The photocatalytic reaction kinetics and mechanism of complexes were investigated. Additionally, complexes also exhibit photocatalytic hydrogen evolution activity. THz-TDS was used to characterize the complexes and its raw materials, the characteristic peaks of OPPh3 (broad peak at 1.20 THz) and phosphotungstic acid (sharp peaks at 0.23, 0.32 THz) were obtained.

Facile high yield, excellent catalytic performance of polyoxometalate-based lanthanide phosphine oxide complexes: Syntheses, structures, photocatalysis and THz spectra.

Water pollution, which continuously threatens human health and the sustainable development of society, has become a major concern. Photocatalytic degradation is an effective strategy to remove organic dyes from wastewater. For this strategy, it is crucial to select the appropriate catalyst. Using triphenylphosphine oxide (OPPh3) as the ligand, phosphomolybdic acid as the anion template, three new lanthanide complexes [Ln(OPPh3)4(H2O)3](PMo12O40)∙4C2H5OH (1-3) (Ln = Sm, Gd, Tb) were synthesized. The raw materials for the reaction are cheap and readily available. The convenient synthesis method is environmentally friendly, with high yield (70%-80%). Complexes 1-3 are all seven-coordinated mononuclear structures centered on lanthanide ions, [PMo12O40]3- anions and solvent molecules are not coordinated with metal ions. These mononuclear structures eventually form complicated 3D supramolecular structures through hydrogen bonds, Mo-O … π or C-H … π weak interactions. Complexes 1-3 photocatalytic degradation of MB have high removal rates, as catalysts have enough stability to be reused, and can be used as excellent catalysts for the degradation of dye molecules in sewage. Among them, the removal rate of MB by photodegradation of complex 2 was highest (99.50%). In addition, the effects of different initial concentrations of MB solution and different types of organic dyes on the photocatalysis experiment were investigated. The photocatalytic reaction mechanism of complexes 1-3 was also studied. Due to the similar structures of complexes 1-3, they have almost the same THz absorption spectra with different absorption intensity, which may be attributed to the difference of the number of weak interactions. Therefore, terahertz spectroscopy can be used as a sensitive method to distinguish and determine small differences between lanthanide-organic complexes. This is the first time that this spectrum has been used to characterize lanthanide phosphine oxide complexes modified by [PMo12O40]3-.

Enantiomeric MOF Crystals Using Helical Channels as Palettes with Bright White Circularly Polarized Luminescence.

The host-guest chemistry of metal-organic frameworks (MOFs) has enabled the derivation of numerous new functionalities. However, intrinsically chiral MOFs (CMOFs) with helical channels have not been used to realize crystalline circularly polarized luminescence (CPL) materials. Herein, enantiomeric pairs of MOF crystals are reported, where achiral fluorophores adhere to the inner surface of helical channels via biology-like H-bonds and hence inherit the helicity of the host MOFs, eventually amplifying the luminescence dissymmetry factor (glum ) of the host l/d-CMOF (±1.50 × 10-3 ) to a maximum of ±0.0115 for the composite l/d-CMOF⊃fluorophores. l/d-CMOF⊃fluorophores in pairs generate bright color-tunable CPL and almost ideal white CPL (0.33, 0.32) with a record-high photoluminescence quantum yield of ≈30%, which are further assembled into a white circularly polarized light-emitting diode. The present strategy opens a new avenue for propagating the chirality of MOFs to realize universal chiroptical materials.

Two Nanometer-Sized High-Nuclearity Homometallic Bromide Clusters (M26Br38)12- (M = Cu, Ag): Syntheses, Crystal Structures, and Efficient Adsorption Properties.

The spontaneous formation of discrete spherical nanosized molecules is ubiquitous in nature; however, the actual structural imitation of such high-symmetry polyhedra from the edge sharing of regular polygons has still proved to be elusive. Herein, two high-nuclearity metal clusters, namely (TTB)4·M26Br38 (M = Cu (1), Ag (2), TTB·Br3 = 1, 3, 5-tris(triethylammoniomethyl)benzene tribromide), have been rationally and solvothermally synthesized and structurally characterized. Single-crystal X-ray analysis confirmed that 1 has I4̅3m symmetry with a (Cu25Br34)12- anion shell enwrapping a CuBr4 tetrahedron and 2 has I4̅3m symmetry with a [Ag26Br34]12- anion shell enwrapping a Br4 pyramid. The diffuse-reflectance UV-vis measurements showed that both compounds possess proper semiconductor behaviors with tunable band gaps of 1.87 eV for 1 and 1.90 eV for 2. Interestingly, all the samples feature distinct adsorption speed and compound 1 shows good adsorption activity for methyl orange (MO) under the same reaction conditions. The effects of pH, temperature, and cyclicity on dye adsorption, together with the thermal stabilities and luminescence properties of the compounds, were also studied. From the cyclic adsorption of compound 1 to the anionic dye MO, it was found that the adsorption of MO was good over three cycles, and the third adsorption rate was still 93.90%.

Hybrid Supramolecules for Azolium-Linked Cyclophane Immobilization and Conformation Study: Synthesis, Characterization, and Photocatalytic Degradation.

In this paper, one imidazole macrocyclic divalent cation with a flexible configuration was chosen with the aim of the immobilization of its conformation. Six novel organic-inorganic hybrid supramolecules {([syn/anti-did](CdI4)(C2H3N)} (1), {([syn/anti-did](HgI4)(C2H3N)} (2), {([syn/syn-did](Pb2I8)(PbI5)} (3), {([syn/syn-did](Bi2I8)(BiI5)} (4), {([syn/syn-did](Ag4Br6)} n (5), and {([syn/anti-did](Ag2I4)} (6) [did2+ = (12z, 52z)-11H, 51H-1, 5(1, 3)-diimidazol-3-iuma-3, 7(1, 2)-dibenzenacyclooctaphane-13, 53-diium] have been synthesized through the self-assembly reaction of did2+ with different metals under solvothermal reaction. These compounds have been unambiguously confirmed by powder X-ray diffraction, IR, thermogravimetric and X-ray single-crystal diffraction. Crystallographic analysis shows that the anions of compounds 1 and 2 are isostructural with mononuclear anion structure, the anions of compounds 3, 4, and 6 are of binuclear structure, and compound 5 anion is a one-dimensional anionic chain structure. Imidazole cyclophanes of organic cations may exist in a syn/syn-conformation in 3-5 or syn/anti conformation in 1, 2, 6, but tilting angles in compounds 1-6 were different. This article described the photocatalytic degradation of organic dye in waste water and the optical band gap of compounds 1-6. The calculated semiconductor band gap of compounds 1-6 is smaller than that of TiO2, so compounds 1-6 have semiconductor properties. Compound 1 has the smallest band gap value, and the photocatalytic performance is the best.

Assembly and Adsorption Properties of Seven Supramolecular Compounds with Heteromacrocycle Imidazolium.

Seven supramolecular compounds comprising multivalent imidazolium macrocycles and metal halides, {[MC-IM][Ag2I4]} n (1), {[PC-IM]2[Ag7I11]} n (2), {[ODC-IM][Ag3I7]} (3), {[ODC-IM][Bi2I10]} (4), {[MDC-IM][Bi2I10]} (5), {[PDC-IM][Bi2I10]} (6), and {[MDC-IM][HgI4]} (7), have been synthesized by solvothermal reactions and structurally characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Notably, the three tetravalent imidazolium macrocycles were introduced for the first time and the extended anion structures are featured with three-dimensional coordination networks, one-dimensional chains, or zero-dimensional oligomers. This new study attempts to not only fill the gap in this supramolecular hybrid area that has been neglected but also enrich the type of imidazolium cyclophane. It is important that good efforts were devoted to study the adsorption properties of supramolecular compounds. Compound 5 exhibited great adsorption performance for organic dyes methylene blue, methyl orange, and rhodamine B (RhB) and can be evaluated as a potential candidate for industrial wastewater treatment.

2,3,3-Trimethyl-1-[4-(2,3,3-trimethyl-3H-indol-1-ium-1-yl)but-yl]-3H-indol-1-ium diiodide.

In the crystal of the title salt, C(26)H(34)N(2) (2+)·2I(-), the dication lies on a center of inversion that exists along the mid-point of the butyl chain; its five-membered ring is approximately planar (r.m.s. deviation = 0.011 Å). In the crystal, the iodide anion is disordered over two positions in a 1:1 ratio.

4,5-Dihydro-3a,5a-diazo-niapyrene triiodidocuprate(I).

In the dianion of the title salt, (C(14)H(12)N(2))[CuI(3)], the Cu(I) atom is coordinated by three I(-) ions that define a nearly trigonal-planar geometry; the Cu(I) atom lies 0.1407 (6) Šout of the plane. With the exception of the methyl-ene C atoms, the dication is essentially planar (r.m.s deviation = 0.067 Å). The most significant inter-action between the ions is a C-H⋯I contact.

1,1'-Di-n-butyl-4,4'-bipyridinium 2.375-bromido-1.625-chloridocadmate.

The title salt, (C(18)H(26)N(2))[CdBr(2.375)Cl(1.625)], consists of non-inter-acting cations and tetra-hedral cadmate(II) anions. The halogen atoms are all disordered, the bromine components being in 0.9035 (17):0.0965 (17), 0.6581 (18):0.3419 (18), 0.5019 (19):0.4981 (19) and 0.6847 (19):0.3153 (18) ratios. The aromatic rings of the cation are twisted by 25.0 (1)°.

1,1'-Methyl-enedipyridinium dichloride monohydrate.

In the crystal structure of the title salt, C(11)H(12)N(2) (2+)·2Cl(-)·H(2)O, the dication adopts a butterfly shape [dihedral angle between rings = 69.0 (1)°] with the water mol-ecule lying in the V-shaped cavity. Each O-H bond of the water molecule lies parallel to an aromatic ring and forms an O-H⋯Cl inter-action to a chloride anion. The methyl-ene C atom in the dication and the water O atoms lie on special positions of twofold site symmetry.

6,7-Dihydro-5H-1,4-diazepino[1,2,3,4-lmn][1,10]phenanthroline-4,8-diium tris-(thio-cyanato-κN)cuprate(I).

The title copper(I) salt, (C(15)H(14)N(2))[Cu(NCS)(3)], exists as non-inter-acting cations and trigonal-planar anions. The cation is buckled, the r.m.s. deviation of the atoms passing through the phenanthroline portion being 0.16 Å. The Cu(I) atom is displaced by 0.019 (2) Šout of the N(3) triangle. The crystal studied was a non-merohedral twin with twin domains in an approximate ratio of 55:45.

Catena-poly[[bis[5-(4-pyridyl-kappaN)-2-(2-pyridylmethylsulfanyl)-1,3,4-oxadiazole]cadmium(II)]-di-mu-thiocyanato-kappa2N:S;kappa2S:N].

The title compound, [Cd(NCS)(2)(C(13)H(10)N(4)OS)(2)](n), contains SCN(-) anions acting as end-to-end bridging ligands which utilize both S and N atoms to link cadmium(II) centers into one-dimensional double chains. The multidentate 5-(4-pyridyl)-2-(2-pyridylmethylsulfanyl)-1,3,4-oxadiazole ligands behave as monodentate terminal ligands, binding metal centers only through the N atoms of the 4-pyridyl groups. Two types of eight-membered rings are formed by two SCN(-) anions bridging Cd(II) centers, viz. planar and chair conformation, which are alternately disposed along the same chain. Finally, chains define a two-dimensional array through two different interchain pi-pi stacking interactions.