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The selective photoreactions under mild conditions play an important role in synthetic chemistry. Herein, efficient and mild protocols for switching the photoreactions of Ir(III)-diamine complexes between the interligand C-N coupling and dehydrogenation are developed in the presence of O

Aerobic photo-oxidation of sulfide into sulfoxide in water is of great interest in green chemistry. In this study, three highly stable Ir(III)–Zr(IV) metal–organic frameworks (Ir–Zr MOFs), namely Z...

Enantiopure Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) (where dfppy is (4,6-difluoropheny)pyridine) were demonstrated to preferentially react with (S,S)-1,2-bis(arylsulfinyl)ethane and (R,R)-1,2-bis(arylsulfinyl)ethane, respectively, under thermodynamic equilibrium. Sequential treatment of Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) with C2-symmetric bis-sulfoxides led to diastereoselective formation of the corresponding diastereomers Λ-[Ir(dfppy)2(R,R)-bis-sulfoxide)](PF6) in 90-92% and Δ-[Ir(dfppy)2(S,S)-bis-sulfoxide)](PF6) in 88-90%, respectively. The uncoordinated (R,S)-bis-sulfoxides were afforded in 45% with >97% de values. Enantiopure (S,S)-bis-sulfoxides and (R,R)-bis-sulfoxides were respectively obtained by the release of sulfoxide ligands from the corresponding complexes in the presence of glycine in yields of 20-21% with 97-99% ee values. The enantioreceptors Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) can be recycled and reused in the next reaction cycle. Moreover, a protocol for asymmetric oxidation of prochiral bis-sulfide into enantiopure C2 symmetric bis-sulfoxide was also developed in a high enantioselectivity. The absolute configurations at the metal centers and sulfur atoms were determined by X-ray crystallography.

Carbazole is an important compound in pharmaceuticals and functional materials. A new Pd(II) supramolecular cage-catalyzed protocol for the synthesis of multifunctional carbazoles from indoles is described through regioselective successive oxidative Heck reactions. This new protocol is highly efficient, with a low Pd (2.4 mol%) catalyst loading and good compatibility for both N-H free and N-protected indole substrates. Moreover, it can be used to synthesize carbazoles with various functional groups by a one-pot two-step procedure. The excellent catalytic activity can be attributed to the distinct properties of the supramolecular cage structure in uniformly distributive and well-defined Pd(II) active centers on the cage surfaces.

The assembly of mixed [1,1';3',1'']terphenyl-4,5',4''-tricarboxylic acid (H3TPTC) and [1,1'-biphenyl]-4,4'-dicarboxylic acid (H2BPDC), 2,2'-diamino-[1,1'-biphenyl]-4,4'-dicarboxylic acid (H2BPDC-NH2), or 6-oxo-6,7-dihydro-5H-dibenzo[ d, f][1,3]diazepine-3,9-dicarboxylic acid (H2BPDC-Urea) with Cu2+ ion generated the corresponding copper-paddlewheel-based metal-organic framework (MOF) [Cu5(TPTC)3(BPDC)0.5(H2O)5] (1), [Cu5(TPTC)3(BPDC-NH2)0.5(H2O)5] (1-NH2), or [Cu5(TPTC)3(BPDC-Urea)0.5(H2O)5] (1-Urea). They are isostructural with hierarchical porosity, consisting of zero-dimensional cage (19.2 A × 18.9 A) and one-dimensional pillar channel (29.7 A × 15.1 A) in a manner of face sharing. Platon analyses revealed the porous volume ratios are 80.2%, 80.0%, and 77.8% for 1, 1-NH2, and for 1-Urea, respectively. Thermogravimetric measurements suggested 53, 51, and 48 wt % guest molecules in 1, 1-NH2, and 1-Urea, respectively. 1-NH2 and 1-Urea were precisely functionalized via the introduction of amino and urea functional groups into the pillar channels. The constructed MOF 1-Urea, incorporating both exposed copper active sites and accessible urea functional groups to substrates, presents high efficiency on catalytic CO2 cycloaddition with propene oxide to produce cyclic carbonate in the yield of 98% with a TOF value of 136 h-1 at 1 atm and room temperature. This synergic effect provides a new strategy for designing high-efficient catalysts for CO2 chemical conversion under ambient conditions.

The chiral-recognition processes of homoproline (hpro) and [Ir(pq)2(MeCN)2](PF6) (pq is 2-phenylquinoline; MeCN is acetonitrile) are investigated, in favor of formation of the thermodynamically stable diastereomers Λ-[Ir(pq)2(d-hpro)] and Δ-[Ir(pq)2(l-hpro)]. Moreover, the diastereoselective photoreactions of Δ-[Ir(pq)2(d-hpro)] and Δ-[Ir(pq)2(l-hpro)] are reported in the presence of O2 at room temperature. Diastereomer Δ-[Ir(pq)2(l-hpro)] is dehydrogenatively oxidized into imino acid complex Δ-[Ir(pq)2(hpro-2H2)] (hpro-2H2 is 3,4,5,6-tetrahydropicalinate), while diastereomer Δ-[Ir(pq)2(d-hpro)] occurs by interligand C-N cross-coupling and dehydrogenative oxidation reactions, affording three products: Δ-[Ir(pq)(d-pqh)] [pqh is N-(2-phenylquinolin-8-yl)homoproline], Δ-[Ir(pq)2(hpro-2H2)], and Δ-[Ir(pq)2(d-hpro-2H6)] [hpro-2H6 is 2,3,4,5-tetrahydropicalinate]. The C-N cross-coupling and dehydrogenative oxidation reactions are competitive, and the dehydrogenative oxidation reactions are regioselective. By optimization of the photoreaction parameters such as the diastereomeric substrate, solvent, and temperature as well as base, each possible competitive product is selectively controlled. In addition, density functional theory calculations are performed to elucidate the distinctly chiral recognition between proline and hpro with an iridium(III) complex.

The postcoordinated interligand-coupling strategy provides a useful and complementary protocol for synthesizing polydentate ligands. Herein, diastereoselective photoreactions of Λ-[Ir(pq)2(d-AA)] (Λ-d) and Λ-[Ir(pq)2(l-AA)] (Λ-l, where pq is 2-phenylquinoline and AA is an amino acid) are reported in the presence of O2 under mild conditions. Diastereomer Λ-d is dehydrogenatively oxidized into an imino acid complex, while diastereomer Λ-l mainly occurs via interligand C-N cross-dehydrogenative coupling between quinoline at the C8 position and AA ligands at room temperature, affording Λ-[Ir(pq)(l-pq-AA)]. Furthermore, the photoreaction of diastereomer Λ-l is temperature-dependent. Mechanistic experiments reveal the ligand-radical intermediates may be involved in the reaction. Density functional theory calculations were used to eluciate the origin of diastereoselectivity and temperature dependence. This will provide a new protocol for the amination of quinoline at the C8 position via the postcoordinated interligand C-N cross-coupling strategy under mild conditions.

A diastereoselective photooxidation of α-amino acid (AA) complexes into imino acid complexes using a chiral iridium(III) complex as a photosensitizer and stereo-controller under visible light irradiation and oxygen was developed. It was found that the oxidative rate of Δ-[Ir(pq)2(L-AA)] (pq is 2-phenylquinoline) diastereomer is significantly higher than that of the corresponding Δ-[Ir(pq)2(D-AA)] diastereomer, providing a new protocol for kinetic resolution of AAs via a nonenzymatic pathway. Moreover, the thermodynamic controlled strategy offered a complemental method for the diastereoselective hydrogenation of imine bonds using NaBH4 as a reductant under the chiral Ir(III) complex as a stereo-controller. The combination of diastereoselective photooxidation and reduction processes results in a new protocol for deracemization of α-amino acids under mild conditions. Mechanism study strongly indicates that singlet oxygen is a key participant in the reaction and the α-C–H bond cleavage of AAs is the rate-dete...

On the basis of hard soft acid base theory, two neutral heterometallic M2Pd3 supramolecular cages, [Al2Pd3(L)6Cl6] (1) and [Fe2Pd3(L)6Cl6] (2) (where HL is 1-(4-(1H-imidazol-1-yl)phenyl)butane-1,3-dione), have been constructed by using the tripodal M(L)3 as metalloligands in combination with PdCl2 or Pd(MeCN)2Cl2. The supramolecular cage can be described as a trigonal bipyramid with two M3+ ions occupying at the two axial sites in ΔΔ or ΛΛ configurations and three Pd2+ ions sitting in the three equatorial positions with square planar geometry in trans configuration. The supramolecular cages exhibit high catalytic activity for the Suzuki–Miyaura coupling with arylbromide or arylchrolide and phenylboronic acid in biorenewable solvent glycerol under mild conditions. Moreover, the catalyst can be readily recycled and reused at least five times without loss of catalytic activity. The high catalytic performance may be attributed to the distinct properties of the cage structure with uniformly distributive and well-defined Pd active centres on the cage surfaces. The high stability in the cage structure also prevents Pd leaching out and agglomeration.

A new chiral sensor assembly with enantiomeric Ir(III) complex Δ-[Ir(ppy)2(MeCN)2](PF6) (ppy is 2-phenylpyridine) and 3-hydroxypyridine-2-carboxaldehyde as anxiliaries for chiral amines and amino derivatives, including α-amines, α-amino alcohols, α-amino esters, β-amines and β-amino alcohols as well as amino ether, was developed on the basis of 1H NMR spectroscopy. The assembly reaction is rapid and quantitative in equivalent under mild conditions, generating the corresponding diastereomers that are applied to discriminate the absolute configuration and quantitatively determine the enantiomeric excess (ee) directly without physical separation. The chelating coordination to Ir(III) ion much enhances the stability of the formed Schiff base ligand. Furthermore, more than one pair of diastereotopic resonances in wide detection regions ensures a convenient and high degree of accuracy in quantifying the ee value of chiral amines and amino derivatives. The absolute errors of the ee determinations by 1H NMR spectroscopy in different detection windows are within 1.9%. The linear relationship between the experimentally measured ee values and the gravimetrically prepared samples is found to be excellent.

Diastereoselective synthesis of bis-cyclometalated Ir(III) stereoisomers Δ/Λ-[Ir(C∧N)2(d-pro)] and Δ/Λ-[Ir(C∧N)2(l-pro)] (where C∧N is 2-phenylpyridine (Hppy), (4,6-difluorophenyl)pyridine (Hdfppy), and 2-phenylquinoline (Hpq) and pro is proline) with dual stereogenic centers at the metal and auxiliary ligand has been developed. The diastereomers Λ-l and Λ-d, and Δ-l and Δ-d exhibit distinguishable photophysical properties in both solution and the solid state. The thermodynamically stable diastereomers Λ-[Ir(ppy)2(l-pro)], Λ-[Ir(dfppy)2(l-pro)], and Λ-[Ir(pq)2(l-pro)] emit a green emission at 524 nm (Φ = 3.5% and τ = 35 ns), a blue-green emission at 480 nm (Φ = 4.5% and τ = 59 ns), and a red emission at 588 nm (Φ = 6.5% and τ = 200 ns) in DCM solution, respectively, which are blue-shifted accompanied by a large quantum yield and long lifetime relative to the corresponding unstable diastereomers Δ-[Ir(ppy)2(l-pro)] at 537 nm (Φ = 2.3% and τ = 29 ns), Δ-[Ir(dfppy)2(l-pro)] at 489 nm (Φ = 2.8% and τ = 43 ns)...

Enantiopure Λ-[Ir(dfppy)

With 2-phenylquinoline (pq) as a cyclometalated ligand, a series of cationic Ir(III) complexes [Ir(pq)2(L1)2](PF6) (L1 is pyridine (1a), 4-methoxypyridine (1b), 4-dimethylaminopyridine (1c), and 4-...

The assembly of mixed [1,1';3',1'']terphenyl-4,5',4''-tricarboxylic acid (H

The optically active Ir(III) complex Λ-[Ir(ppy)2(MeCN)2](PF6) (ppy is 2-phenylpyridine) with a chiral-at-metal was first demonstrated to preferentially react with (R)-configuration sulfoxides 2-(alkylsulfinyl)phenol (HLO-R, R = Me, Et, iPr, and Bn) rather than (S)-configuration sulfoxides under thermodynamic equilibrium due to the hydrogen-bonding interaction and the differences in the steric interference, and thus act as a highly efficient enantioreceptor for resolution of sulfoxide enatiomers. Treatment of Λ-[Ir(ppy)2(MeCN)2](PF6) with 2 equiv of rac-HLO-R offered (S)-HLO-R in yields of 46–47% with 97–99% enantiomeric excess (ee) values and Λ-[Ir(ppy)2{(S)-LO-R}] complex in yields of 89–93% with 98% diastereomeric excess (de). The (R)-HLO-R chiral sulfoxides were obtained by the acidolysis of Λ-[Ir(ppy)2{(S)-LO-R}] complexes with trifluoroacetic acid (TFA) in the presence of coordinated solvent MeCN in yields of 45–47% with 98–99% ee values. Moreover, the enantioreceptor Λ-[Ir(ppy)2(MeCN)2](PF6) can be ...

With the idea of supramolecular hosts encircling monoanions, a series of urea-containing trinuclear cationic copper complexes were designed, prepared and structurally analyzed. Copper(I) acetylides [Cu3(μ-dppm)3(μ3-η1-CCC6H4-4-NHC(O)NHC6H4-4-R)2]+ (dppm = bis(diphenylphosphino)methane; R = NO2 (1), CF3 (2), Cl (3), H (4), tBu (5), and OCH3 (6)) were prepared with F−, BF4−, or NO3− present as the anion. Eight 1-D anion coordination polymers (ACPs), 1·F, 2·F, 3·BF4, 4·F, 5·F, 5·BF4, 5·NO3 and 6·0.5F·0.5BF4, were clearly determined by X-ray diffraction. Diversity in the polymeric architecture is generated by both the choice of R-group used and anion present. 2·F, 3·BF4, 4·F, and 5·F show linear 1-D structures; 5·BF4 and 5·NO3 feature single-stranded helical structures; 1·F and 6·0.5F·0.5BF4 exhibit meso-helical structures. Solid state UV-vis absorption and luminescence properties are also discussed.

A convenient and practical procedure to prepare Pd(II) metallogel as a highly efficient and recyclable catalyst for Suzuki-Miyaura coupling has been developed. Such metallogel shows highly processable and reversible responses to thermal and mechanical stimuli. The xerogel is a highly efficient (0.005 mol% Pd) heterogeneous catalyst for Suzuki-Miyaura couplings with arylhalides and phenylboronic acids in excellent yield in water or ethanol under ambient atmosphere. The reaction could be scaled up to 10 gram scale with 0.001 mol% Pd catalyst loading with 99% yield. The catalyst can be recycled and reused at least seven times without loss of activity.

Chiral precursors Λ-[Ir(ppy)2(l-pro)] (Λ-L, where ppy is 2-phenylpyridine; pro is proline), Λ-[Ir(ppy)2(MeCN)2](PF6) (Λ-1), Δ-[Ir(ppy)2(d-pro)] (Δ-D), and Δ-[Ir(ppy)2(MeCN)2](PF6) (Δ-1) were synthesized from rac-[(Ir(ppy)2)2Cl2] and l-pro or d-pro by means of the auxiliary ligand strategy with 99% de values. The enantiopure mono complexes Λ/Δ-[Ir(ppy)2(L)](PF6) (L is 2,2'-bipyridine, Λ/Δ-2; L is 2,2'-dipyrimidine (dpm), Λ/Δ-3; L is 2,2'-bibenzimidazole (H2bbim), Λ/Δ-4) with 99% ee values and binuclear complexes ΛΛ/ΔΔ-[(Ir(ppy)2)2(dpm)](PF6)2 (ΛΛ-5 and ΔΔ-5) and ΛΛ/ΔΔ-[(Ir(ppy)2)2(bbim)] (ΛΛ-6 and ΔΔ-6) with 99% de values were synthesized in one step using the corresponding chiral precursors. The absolute configurations at Ir(III) centers of precursor Δ-1, mononuclear Λ-3, and binuclear ΔΔ-6 were confirmed by single-crystal structural analysis and characterized by circular dichroism (CD) spectroscopy. The correlation between the absolute configuration at Ir(III) center and CD spectra was established. The configurations at Ir(III) centers are stable during the reactions, and the chiral precursors can be used for the asymmetric synthesis of enantiomerically pure mono- and polynuclear Ir(III) complexes. Moreover, meso ΛΔ-[(Ir(ppy)2)2(dpm)](PF6)2 (meso-5) and ΛΔ-[(Ir(ppy)2)2(bbim)] (meso-6) were also synthesized using these precursors.

Aerobic oxidation of amino acid complexes is an important process for the functionalization of amino acids. However, the reaction mechanism is still uncertain. Two enantiopure imino acid complexes Δ-[Ir(pq)2(ala-2H)] and Δ-[Ir(ppy)2(ala-2H)] (where pq is 2-phenylquinoline, ppy is 2-phenylpyridine and ala is alanine) have been synthesized respectively via the dehydrogenated oxidation reaction of the corresponding amino acid complexes Δ-[Ir(pq)2( l -ala)] and Δ-[Ir(ppy)2( l -ala)] in EtOH using visible light as the driving force and oxygen as an oxidant under mild conditions. The imino acid complexes have been fully characterized by NMR and MS techniques as well as X-ray single-crystal determination. The mechanism studies show singlet oxygen (1O2) is the main reactive oxygen species (ROS) and the carbon radical intermediate may involve in the reaction process. Therefore, a reaction mechanism involving the formation of a ligand-radical intermediate rather than the higher oxidation state of the metal center was proposed.

An efficient approach for direct carbamoylation of terminal alkynes with formamides affording propiolamides has been developed by copper-catalyzed oxidative cross coupling of C(sp)-H and C(sp2)-H bonds in the presence of a pincer ligand with two imidazolyl groups. The catalytic reaction is compatible with diverse functional groups but sensitive to the electronic effect of terminal alkyne and the steric effect of formamides. KIE study indicates the cleavage of the carbamoyl C–H bond affording formamide radical is the rate-determining step.

The enantioselective oxidation synthesis of chiral modafinil acid and its analogues with high enantiomeric excess has been developed by means of a chiral-at-metal strategy. Treatment of ruthenium complexes cis-[Ru(bpy)2Cl2] or Δ/Λ-[Ru(bpy)2(MeCN)2](PF6)2 (bpy is 2,2′-bipyridine) with the appropriate prochiral thioether ligands afforded thioether complexes rac-1, Δ/Λ-1, rac-2, Δ/Λ-2, rac-3, and Δ/Λ-3. Diastereoselective oxidation of the thioether complexes in situ produced the corresponding sulfoxide complexes rac-1a, Δ/Λ-1a, rac-2a, Δ/Λ-2a, rac-3a, and Δ/Λ-3a. The configuration at the metal center in each case is stable during the coordination and oxidation reactions, and dictates the chirality of the sulfoxide ligand in the oxidation process. The chiral modafinil acids were obtained with ee values greater than 98 % upon their removal from the corresponding sulfoxide complexes in the presence of TFA/MeCN. Moreover, the chiral ruthenium precursors Δ/Λ-[Ru(bpy)2(MeCN)2](PF6)2 are recyclable and reusable with complete retention of the configurations.

A three-component protocol involving enantiopure Δ-[Ir(ppy)2(MeCN)2](PF6) (ppy is 2-phenylpyridine) and salicylaldehyde as chiral auxiliaries was successfully applied to discriminate the absolute configuration and determine the enantiopurity of primary amines and amine alcohols via 1H NMR spectroscopy. The assembly reaction is rapid and quantitative, generating a pair of diastereomers that can be determined directly without physical separation. Single crystal structural analyses indicate that the shielding effects on the ligands imposed by a pair of diastereomers are different and generate sufficient resolution NMR signals for identification. The enhancement of stability via chelating coordination to Ir(III) ion and more than one pair of diastereotopic resonances in different detection regions of the three-component protocol ensure a high degree of accuracy in quantifying the ee value of chiral amines. The absolute errors in the ee determinations by 1H NMR spectroscopy in different detection windows are w...

Treatment of cis-[Ru(bpy)2Cl2]⋅2 H2O or Δ/Λ-[Ru(bpy)2(py)2]2+ (bpy=2,2′-bipyridine, py=pyridine) with the prochiral thioether ligands 2-alkylthiobenzoic acid (HOSR) produces the corresponding thioether complexes rac-[Ru(bpy)2(OSR)](PF6) (R=Me (rac-1), iPr (rac-2), 2-benzylthiobenzonate (Bn) (rac-3)) and Δ/Λ-[Ru(bpy)2(OSR)](PF6) (R=Me (Δ-1/Λ-1), iPr (Δ-2/Λ-2), Bn (Δ-3/Λ-3)) with retention of the configurations at chiral metal centers. In situ oxidation of the thioether complexes by meta-chloroperoxybenzoic acid provides the corresponding sulfoxide complexes rac-[Ru(bpy)2(OSOR)](PF6) (OSOR is 2-alkylsulfinylbenzonate, R=Me (rac-1 a), iPr (rac-2 a), Bn (rac-3 a)), Δ-[Ru(bpy)2{(R)-OSOR}](PF6) (R=Me (Δ-1 a), iPr (Δ-2 a), Bn (Δ-3 a)), and Λ-[Ru(bpy)2{(S)-OSOR}](PF6) (R=Me (Λ-1 a), iPr (Λ-2 a), Bn (Λ-3 a)) in yields of 95 % with 98 % ee values. The absolute configurations at the metal centers and sulfur atoms were determined by means of X-ray crystallography. The results indicate that the configurations of the metal centers are retained and have the function of controlling sulfoxide chirality during the oxidation process. The Δ metal-centered configuration enantioselectively generates an R-configuration sulfoxide, and the Λ configuration enantioselectively forms an S-configuration sulfoxide in the course of the in situ oxidation reaction, thereby resulting in a predetermined chirality of the sulfoxide ligands. The predetermined chirality of sulfoxides (S)-HOSOR and (R)-HOSOR were obtained by the treatments of the corresponding sulfoxide complexes Δ-[Ru(bpy)2{(R)-OSOR}](PF6) and Λ-[Ru(bpy)2{(S)-OSOR}](PF6) with trifluoroacetic acid in yields of 90 % with 83.5–92.9 % ee values.

A new ruthenium biimidazole-like anion receptor featuring two “chelating” N H⋯O intramolecular hydrogen bonds, [Ru(bpy)2(DNBbimH2)](PF6)2 (2·(PF6)2) (bpy = 2,2′-bipyridine; DNBbimH2 = 5,5′,6,6′-tetramethyl-7,7′-dinitro-2,2′-bibenzimidazole), has been synthesized. Its anion-binding ability towards different anions in acetonitrile has been studied.

Three novel coordination polymers have been synthesized via hydrothermal reactions at different temperatures, namely [Cu2(H2tcbi)(H2O)4] (1), [Cd3(H3tcbi)2(H2O)6]·2H2O (2) and [Ca(H4tcbi)(H2O)2] (3) (H6tcbi = 4,4′,5,5′-tetracarboxyl-2,2′-biimidazole). This is the first report on complexes of the Hntcbi ligand. Single crystal X-ray analyses reveal that they have rich structural chemistry, ranging from one-dimensional (1), to two-dimensional (2 and 3). Three different coordination modes of the H6tcbi ligand, μ2, μ3 and μ4, have been observed. The coordination geometries of the metal sites vary from five-coordinate square pyramidal, six-coordinate octahedral to seven-coordinate pentagonal bipyramidal. The H6tcbi ligand in complexes 1, 2 and 3 is tetra-deprotonated to H2tcbi4−, tri-deprotonated to H3tcbi3− and bi-deprotonated to H4tcbi2−, and coordinates to the metal ions as a tetradentate, pentadentate and pentadentate ligand respectively, resulting in the formation of 1D, 2D and 2D coordination polymers. Photoluminscent investigation of complexes 2 and 3 shows intense blue and green fluorescent emissions respectively.

Two isostructural 1D coordination polymers {[Ln(OAc)2(H2O)(OBPT)]·3H2O}n (HOBPT = 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol, Ln = Eu(3+), 1; Tb(3+), 3) and two discrete complexes [Ln(OAc)2(DMF)2(OBPT)] (Ln = Eu(3+), 2; Tb(3+), 4) have been synthesized in H2O-MeOH or DMF solvents, respectively. Their structures were identified by powder X-ray diffraction. Single-crystal X-ray studies for complexes 1 and 2 revealed that the coordination geometries of the Eu(3+) ions are similar and can be described as a distorted tricapped trigonal prism with six oxygen atoms and three nitrogen atoms. The difference between them is that one aqua ligand and one oxygen atom from the OBPT ligand complete the coordination sphere in complex 1, whereas two DMF molecules complete the coordination sphere in complex 2. Interestingly, the solvent-mediated, reversible crystal-to-crystal transformation between them was achieved by immersing the crystalline samples in the corresponding solvent (H2O or DMF) or by exposing them to solvent vapor. Complex 1 shows a highly selective luminescence enhancement in response to DMF in comparison to that observed in response to other examined solvents such as acetone, ethyl acetate, ethanol, acetonitrile, methanol, and THF.

The novel three-dimensional chiral framework of the four-coordinate zinc complexes, [Zn 4 (biim) 3 (ina) 2 ] ( 1a and 1b ) (H 2 biim = 2,2′-biimidazole, ina = isoniconate), has been prepared via hydrothermal reaction. X-ray single crystal diffraction analysis shows the biim 2− in title complexes acts as a tetradentate ligand and links four different Zn 2+ ions. Spontaneous chiral resolution occurs in solvo-thermal reaction, which was confirmed by solid-state circular dichroism spectra. Photoluminescent spectra of compound 1 exhibit an intense blue emission at 440 nm.

Six new complexes [Zn2(L1)4]·2H2O·DMF (1), [Zn2(L2)4]3·13H2O (2), [Zn1.5(L3)3]2 (3), Zn(L4)2·2H2O (4), Zn(L5)2·2CHCl3 (5), and [Zn(L6)2]2 (6) (where HL1 = 1-(4-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL2 = 1-(4-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione, HL3 = 1-(4-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione, HL4 = 1-(3-(1H-imidazol-1-yl)phenyl)butane-1,3-dione, HL5 = 1-(3-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione and HL6 = 1-(3-(1H-pyrazol-1-yl)phenyl)butane-1,3-dione) have been synthesized by the reaction of the bifunctional ligands and Zn(II) salts under similar experimental conditions. Structural analyses show that the ligands act as a tridentate and bind to two Zn(II) ions as a two-connected linker, generating a variety of geometries from discrete binuclear [2 + 2] metallomacrocycles (3 and 6) to a one-dimensional looped-chain coordination polymer (4) and two-dimensional (4,4) network (5) as well as three-dimensional frameworks with lvt (1) and NbO (2) topologies. The results demonstrate that ...

Two new mercury(II) complexes [Hg(TDMPT)Cl2] (1) and [Hg37(TDMPT)12Br74] (2) (TDMPT = 2,4,6-tris(3,5-dimethylpyrazolyl)-1,3,5-triazine) have been prepared and characterized by X-ray structural analysis. Mercury(II) complex 1 is a mononuclear coordination compound. Meanwhile, mercury(II) complex 2 is the first example of the 3D coordination polymer with a 1D inorganic chain based on the Lindqvist-type [Hg6Br19]7− anion as building blocks. Furthermore, the bromide anions act as terminal, μ2- and μ6-bridge ligands.

Seven complexes based on the ligands 4,6-bis(4-pyridyl)-1,3,5-triazin-2-ol (4-HOBPT) and 4,6-bis(3-pyridyl)-1,3,5-triazin-2-ol (3-HOBPT), namely, [Fe(4-OBPT)2(H2O)2]·6H2O (2), M(4-OBPT)(INA)(H2O) (M = Co(II) (3a), Fe(II) (3b), Zn(II) (3c), HINA = isonicotinic acid), [Co(3-OBPT)2(H2O)2]·H2O (4), and [M(3-OBPT)(NA)(H2O)]·0.5CH3OH (M = Co(II) (5a), Ni(II) (5b), HNA = nicotinic acid), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The thermal stability and coordination model of the ligands are extremely dependent on the reaction temperature and the presence of metal ions. In the range of 90−120 °C, unique complexes 2 and 4 were obtained and the ligands are a N,O-bimonodentate coordination model. At 130 °C, complexes 3 and 5 were afforded in yields of 12−48% depending on the metal ions, in which both of the ligands act as a N,N,O-trimonodentate triangular ligand and the INA and NA anions are generated in situ by hydrolysis of the corresponding parents...

The complexes [Pd(phen)(aa)]Cl·3H2O, where phen is 1,10-phenanthroline and as is the anion of glycine (gly), DL-alanine (ala), DL-serine (ser) or DL-asparagine (asn), were synthesized and characterized by spectroscopies. The NMR signals were assigned completely on the basis of the double irradiation, 1H-1 H COSY and 1H-13C COSY techniques. In the 1H NMR spectra of phen in the complexes, the signals of 2-H and 9-H show upfield shifts 0.8–1 ppm, while the signals of 4-H and 3-H show downfield shifts or almost no shift, as compared to the free phen ligand, and the signal of 4-H appears in the lowest field. The signals of ring B which is trans to the carboxyl group show significant upfield shirts as compared to those of ring A. The probable structures were described on the basis of a metal-non-bonded hydrogen interaction, trans effect and ligand-ligand interaction. There may exist three conformation isomers in the [Pd(phen)(asn)]Cl·3H2O complex at room temperature. The preferred conformation isomer is about 75% in terms of the relative peak areas in the α-CH part of the spectra.

We describe the first observation of the quantitative and rapid synthesis ofa (10,3)-b three-dimensional hydrogen bonded network {[Ru(H 2 biim) 3 ](TMA)}·5H 2 O(1·H 2 O)(H 2 biim = 2,2'-biimidazole; H3TMA = trimesic acid) via a "liquid-assisted" solid-state reaction approach. The reaction occurs within minutes of grinding together [Ru(H 2 biim) 3 ](PF 6 ) 2 and Na 2 HTMA with a few drops of H 2 O 2 as an oxidant and solvent, concomitant with a color change from yellow (Ru(II) ion) to blue-green (Ru(III) ion). The characterization of the solid-state product was achieved by a combination of a single crystal obtained via seeding and powder diffraction experiments. To compare with the solid-state reaction, similar reactions were also carried out in an EtOH solution. Two complexes {[Ru(H 2 biim) 3 ](TMA)}·10H 2 O(2·H 2 O) and [Ru(H 2 biim) 3 ](HTMA) (3) were isolated in the presence of a polypyridine base, such as 2,2-dipyridylamine or 2,2':6',2"-terpyridine or 1,10-phenanthroline. Complex 2 is a (6,3) honeycomb two-dimensional hydrogen-bonded network. Complexes 1 and 2 are topological isomers. The formation of multiple robust hydrogen bonds between [Ru(H 2 biim) 3 ] 3+ and TMA may trigger the proton transfer from H 2 biim to TMA, then electron transfer, resulting in Ru(III) status. This may provide an effective approach for the generation of high status metal complexes via supramolecular interactions. Importantly, our experiments suggest that solution crystallization may at times offer more product diversity than grinding.

A nanocage complex [Co(H2O)6⊂Co8L12](NO3)6·12H2O (1) (HL = 2-amino-4,6-bis(2-pyridyl)-1,3,5-triazin) has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction. A [Co(H2O)6]2+ ion as a guest is included in the central cavity of the cubelike nanocage [Co(H2O)6⊂Co8L12]6+ cation, assembled by 8 cobalt ions at the corners and 12 bis-bidentate ligands L at the edges, via the formation of 12-fold strong hydrogen bonds between the six coordinated water molecules and the nitrogen atoms of 12 L ligands. When compound 1 cocrystalizes with KHCO3 and trimesic acid (H3TMA), complexes [Co(H2O)6⊂Co8L12](HCO3)6·24H2O (2) and [Co(H2O)6⊂Co8L12](H2TMA)6·6EtOH·3H2O (3) are obtained, respectively. In 2, a planar [(HCO3)2]2− dimer motif R22(8) synthon plus six lattice water molecules constitute a planar supramolecular synthon R88(20), which acts as a 4-connector, generating a three-dimensional (3D) hydrogen-bonded NbO net with an approximately 20 A diameter cavity. In 3, the R44(24...

Five different cobalt complexes were synthesized by the combination of the multidentate ligand 2,2′-bibenzimidazole (H2bbim) and the coordination plasticity of cobalt ion in the presence of 4-cyanopyridine under hydrothermal conditions using temperature as the only independent variable. The structural features of theses complexes, which ranged from zero-dimensional (0D) in [Co(Hbbim)3]·3H2O (1) and [Co(ina)2(H2O)4] (5) to two-dimensional (2D) layer in {[Co4(Hbbim)4(bbim)2]·2H2O}n (2) or three-dimensional (3D) networks in [Co2(Hbbim)(bbim)2(H2O)]n (3) and [Co5(Hbbim)(bbim)3(ina)2(μ3-OH)]n (4), were extremely dependent on the reaction temperature. At 130 °C, discrete 1 was the unique product. However, 4 was the main product when the reaction temperatures were set in the range of 160−200 °C. 2 and 3 yielded at 140 °C as main products. In spite of the structural diversity of this system, crystallographic studies reveal that the H2bbim ligand typically displays tridentate (Hbbim−) and/or tetradentate (bbim2−) ...

Six complexes containing the 2,2′-biimidazole-like ligand and chloride, namely, trans-[Ni(H2biim)2(H2O)2]Cl2 (1), trans-[Co1.5(H2biim)3(H2O)3]Cl3 (2), [Zn(H2biim)2Cl]Cl (3), [Ni2(H2bbim)4(bbim)]Cl2 (4), [Co(H2bbim)3]Cl2·2H2O (5), and [Zn2(Hbbim)2(bbim)0.5Cl] (6) (where H2biim = 2,2′-biimidazole, H2bbim = 2,2′-bibenzimidazole) have been synthesized by the reactions of the H2biim or H2bbim ligand with the metal chloride salts. The structures of the complexes were determined by single-crystal X-ray diffraction analyses, and the results revealed that the distances of N···Cl varied from 3.10 to 3.29 A and the angles of N−H···Cl varied from 148 to 169°, O···Cl varied from 3.09 to 3.16 A, O−H···Cl varied from 151 to 178°, C···Cl varied from 3.49 to 3.69 A, and C−H···Cl varied from 122 to 167°. The chloride may act as a multi hydrogen bonded acceptor varying from 3 to 6, resulting in an important collective contribution to cohesion. The data observed in this study seem to suggest that a variety of X−H···Cl (X = N...