Huiyeong Ju

Ligand-Induced Formation of Copper(I) Iodide Clusters: Exocyclic Coordination Polymers with Bis-dithiamacrocycle Isomers

A comparative study on the formation of guest clusters induced by different shapes (or sizes) of exocyclic binding sites embedded in the bis-macrocyclic host isomers is reported. CuI reacts with two regioisomers of a bis-dithiamacrocycle, o-bis-L (W-shaped binding site) and m-bis-L (U-shaped binding site), to yield one-dimensional coordination polymers {[(μ4-Cu4I4)(o-bis-L)]·2CH3CN}n (1a) and [(μ4-Cu2I2)(m-bis-L)]n (2). In 1a, the o-bis-L ligand isomer is linked by a spacious cubane [Cu4I4] cluster, while the m-bis-L ligand in 2 is linked by a smaller rhomboid [Cu2I2] cluster because of the different exocyclic binding sites. The results observed illustrate the possibility for the metal clusters including [CunIn] (n = 2 or 4) to adopt a controlled formation through the binding site alternation or design. Because of the adaptive cluster formations, the products show different photophysical properties. Additionally, sliding of the one-dimensional chains in 1a was observed upon loss of the lattice solvent molecules in ambient condition.

Cation-Selective and Anion-Controlled Fluorogenic Behaviors of a Benzothiazole-Attached Macrocycle That Correlate with Structural Coordination Modes

We report how the metal cation and its counteranions cooperate in the complexation-based macrocyclic chemosensor to monitor the target metal ion via the specific coordination modes. The benzothiazolyl group bearing NO2S2-macrocycle L was synthesized, and its mercury(II) selectivity (for perchlorate salt) as a dual-probe channel (UV-vis and fluorescence) chemosensor exhibiting the largest blue shift and the fluorescence turn-off was observed. In the mercury(II) sensing with different anions, except ClO4(-) and NO3(-), no responses for mercury(II) were observed with other anions such as Cl(-), Br(-), I(-), SCN(-), OAc(-), and SO4(2-). A crystallographic approach for the mononuclear mercury(II) perchlorate complex [Hg(L)(ClO4)2]·0.67CH2Cl2 (1) and polymeric mercury(II) iodide complex [Hg(L)I2]n (2) revealed that the observed anion-controlled mercury(II) sensing in the fluorescence mainly stems from the endo- and exocoordination modes, depending on the anion coordinating ability, which induces either the Hg-Ntert bond formation or not. The detailed complexation process with mercury(II) perchlorate associated with the cation sensing was also monitored with the titration methods by UV-vis, fluorescence spectroscopy, and cold-spray ionization mass spectrometry.

Macrocyclic isomer-dependent supramolecular silver(I) complexes via endo/exo-coordination modes: a tetranuclear bis(macrocycle) complex vs. a 2D coordination polymer

A comparative investigation of the coordination behaviour of the regio-isomers (o-L and p-L) of the tribenzo-O2S2-macrocycle (L) is reported. On silver(I) complexation, the macrocycle incorporating an o-xylyl group (o-L) yields a discrete endo/exocyclic tetranuclear bis(macrocycle) complex. On the other hand, the corresponding p-xylyl analogue (p-L) gives a 2D square-grid coordination network via exocyclic coordination.

Influence of Anion and Mole Ratio on the Coordination Behavior of an NO2S3-Macrocycle: The Formation of a Dumbbell-Shaped Macrocyclic Cadmium(II) Iodide Complex

Anion and mole ratio dependent formations of cadmium(II) complexes with an NO2S3-macrocycle (L) incorporating a pyridine subunit are reported. When the cadmium(II) salts (1-10 equiv) with different halide ions (Br(-) or I(-)) were reacted with L, CdBr2 afforded a monomer complex, [Cd(L)Br]2[Cd2Br6]·CH2Cl2 (1), with three separated parts in the whole mole ratio range: two 1:1 stoichiometric complex cation parts and one Cd2Br6 cluster anion part. After separation of 1 by filtration, [Cd(L)Br]2[CdBr4]·CH2Cl2 (2) with similar composition was afforded, except the cluster was isolated from the filtrate. Unlike the CdBr2 complexation, CdI2 afforded the mole ratio dependent products (3-5). Below 2.5 equiv of CdI2, [Cd(L)I]2[CdI4]·CH2Cl2 (3) and [Cd(L)I]2[Cd2I6]·0.5CH2Cl2 (4) with different cadmium(II) iodide clusters were isolated as kinetic (3) and a thermodynamic (4) products. Notably, the use of 3 equiv or above amount of CdI2 gave a dumbbell-shaped complex, {[Cd(L)]2(μ-Cd4I12)} (5), in which two mononuclear macrocyclic complex units are linked by a (μ-Cd4I12)(4-) cluster. To monitor the mole ratio dependency as well as their reactivities, the systematic powder X-ray diffraction (PXRD) analysis has also been applied.

Cation-directed assembly of polyrotaxane and polycatenane

Divalent metal (Pb or Zn) coordination polymers containing 1,4-bis(4-pyridyl)piperazine (bpp) and 4,4′-sulfonyldibenzoic acid (H2sdb) exhibit different interlocked topologies. In [Pb2(sdb)2(bpp)]n (1), two Pb(II) generate Pb2(sdb)2 metallacycles connected by bpp ligands, leading to the formation of a 1D + 1D → 1D polyrotaxane. In contrast, in {[Zn2(sdb)2(bpp)2]·2DMA}n (2), tetrameric metallacycles Zn4(sdb)4 are interlocked, generating 1D polycatenated chains in a parallel manner and are further pillared by bpp ligands to build a 3D framework.

Guest-triggered assembly of zinc(II) supramolecular isomers with accompanying dimensional change and reversible single-crystal-to-single-crystal transformation

Solvent-directed assembly of two-dimensional (2D) and 3D supramolecular isomers as well as guest-exchange induced transformation of the 2D isomer accompanied by photoluminescence switching are reported. Solvothermal reaction of Zn(NO3)2·4H2O, 1,4-bis(4-pyridyl)piperazine (bpp), and benzene-1,3-dicarboxylic acid (H2bdc) in dimethylformamide (DMF) afforded a self-penetrated 3D coordination polymer, {[Zn2(bpp)2(bdc)2]·4DMF·4H2O}n (1), adopting a firewood-like stacking structure. When the above synthetic procedure was repeated employing dimethylacetamide (DMA) as a solvent, a 2D coordination polymer, {[Zn2(bpp)2(bdc)2]·4DMA·6H2O}n (2), was obtained, whose structure shows a crinkled square (4,4) grid type, as a supramolecular isomer of 1. The dimensional difference between isomers 1 and 2 stems mainly from the directional arrangement and the conformation of the bpp ligand. In the guest-exchange experiment, isomer 2 with the crinkled square grid structure not only represents a reversible spreading–folding conversion due to the conformational change of the bpp ligand but also displays a photoluminescence switching behaviour.

Guest-Induced 2-D Metallopolycapsular Networks Based on a 1,3-Alternate Calix[4]arene Derivative

Solvothermal reactions of the calix[4]arene tetraacetic acid (H4 CTA) with zinc nitrate in the presence of α,ω-diaminoalkanes afford two-dimensional metallopolycapsular networks of the formula {[Me2 NH2 ]2 [G@(Zn2 (CTA)2 )]⋅(DMF)2 ⋅(H2 O)4 }n (G=(+) NH3 -(CH2 )n -NH3 (+) , n=2, 3, 4; DMF=N,N-dimethylformamide). These metallopolycapsular networks are built up of metallocapsules that consist of two CTA and two Zn(II) ions. Short alkanediyldiammonium ((+) NH3 -(CH2 )n -NH3 (+) , n=2, 3, 4) guest ions are accommodated in each capsule of the metallopolycapsular network through a variety of supramolecular interactions. The thermal behaviours and the solid-state photoluminescent properties of these complexes were also investigated.

Copper(I) bromide complexes of two 15-memberd O2S2-macrocycles with different sulfur-to-sulfur separations: dimer and one-dimensional coordination polymer

Abstract A comparative study on the exo-coordination-based networking of 15-membered O2S2-macrocycle isomers (L1 and L2) induced by interdonor distances is reported. In copper(I) bromide complexation, the isomer L1 incorporating a shorter sulfur-to-sulfur separation yielded a discrete dimer complex [(μ-Cu2Br2)(L1)2] (1) in which two macrocycles are bridged by a Cu2Br2 square cluster. While, the reaction of copper(I) bromide with the isomer L2 incorporating a longer sulfur-to-sulfur separation afforded a double-stranded one-dimensional (1D) coordination polymer {[(μ4-Cu2Br2)(L2)2]·CH2Cl2}n (2) as a kinetic product which converted to [(μ4-Cu2Br2)(L2)2]n (3) with different 1D connectivity pattern as a thermodynamic product. The results indicate as examples of programmed self-assembly that the proposed interdonor distances and the ligand isomerism play decisive roles cooperatively in the topologies of the supramolecular products via different coordination modes.

Endocyclic and Endo–Exocyclic Silver(i) Complexes of Thiaoxaaza Macrocycles: Crystallographic and NMR Studies

A comparative investigation of the coordination behaviour of a 19-membered NO2S2-macrocycle (L1) and a 20-membered NO2S3-macrocycle (L2) is reported. On silver(i) complexation, L1 yields a discrete endocyclic mononuclear complex, whereas L2 affords a one-dimensional coordination polymer in which the endo-coordinated macrocyclic complex units are linked by silver(i) ions outside the cavity via endo–exo-coordination. The larger ring cavity along with the flexible nature of L2 may induce the weaker endocyclic complexation and contribute to exocyclic coordination as well. In NMR titration studies for the corresponding complex system, however, no evidence of exocyclic coordination was observed. Instead, L1 and L2 form a stable endocyclic 1 : 1 silver(i) nitrate complex, with a higher affinity for the former ligand.

Endo- and Exocyclic Coordination of a 20-Membered N2O2S2-Macrocycle and Cascade Complexation of a 40-Membered N4O4S4-Macrocycle

A 20-membered N2O2S2-macrocycle (L1) and a 40-membered N4O4S4-macrocycle (L2) were employed as a [1:1] and a [2:2] cyclization product, respectively, for the preparation of diverse types of supramolecular complexes including a cascade complex. Six complexes (1-6) of the smaller macrocycle L1 including discrete to continuous forms, mono- to heteronuclear, and endo- to exo- and endo/exocoordination were prepared and their coordination modes were discussed systemically. First, the reaction of L1 with CuI in the presence of trifluoroacetic acid afforded an exocyclic 1-D coordination polymer {[(μ4-Cu4I4)(HL1)2](CF3COO)2} n (1). Meanwhile, the reaction of L1 with Cu(ClO4)2·6H2O afforded a typical endocyclic mononuclear complex [CuII(L1)](ClO4)2·H2O (2). In the reactions of L1 with CdX2 (X = Br and I), isostructural sandwich-type complexes [Cd(L1)2Br2] (3) and [Cd(L1)2I2] (4) were isolated. The treatment of L1 with Hg(ClO4)2 also afforded a sandwich-type complex [Hg(L1)2](ClO4)2 (5). One-pot reaction of L1 with a mixture of HgI2 and CdI2 afforded a dumbbell-type heteronuclear complex {[Cd(L1)]2(μ-Hg2I6)}[Hg2I6] (6), in which the Cd(II) ion occupies the macrocyclic cavity. Further, such two endocyclic Cd(II) complex units are bridged by a square-type (μ-Hg2I6)2- cluster remaining another same cluster separately. The comparative NMR data exhibited a higher affinity of Cd(II) over Hg(II) toward L1, in the parallel to the situation occurred in the solid state. Meanwhile, complexations of the extra-large macrocycle L2 is more challenging to afford some interesting dimercury(II) coordination products including a cascade complex. In solution, the dimercury(II) perchlorato complex of L2 as a metalloligand shows a preferential binding of dabco (1,4-diazabicyclo[2,2,2]octane), but its dimercury(II) iodo complex has a much smaller affinity for dabco. In order to explain these results, the solid dimercury(II) complexes with different anions [Hg2(L2)X4] (7: X = I, 8: X = ClO4) were prepared and characterized. Further, the dimercury(II) perchlorato complex 8 reacts with dabco to forms a cascade complex [Hg2(L2)(μ-dabco)(ClO4)2](ClO4)2·2DMF·2ether (9), exhibiting its formation being metal-driven and coordinated anion-regulated. The observed cascade complexation both in solution and solid states is an example of the adaptive guest binding.