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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

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.

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)...

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 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 ...

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.

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...

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.

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.

The reaction of 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)benzene (bib) ligand with silver(I) nitrate in a 1:1 molar ratio generated a [2 + 2] metallocyclic complex [Ag2(bib)2](NO3)2 · 2H2O, in which bib ligand displayed in cis configuration. When the additional competing ligands/counterions, such as oxlate salt, 1,2-diaminoethene (en), 1,3-diaminopropane (pn), NO 2 - and VO 3 - were introduced, respectively, to the above-mentioned reaction solution, ring-open polymerization of sliver(I) complexes {[Ag(bib)]NO3 · H2O}n (1), {[Ag(bib)2]X}n ( X = NO 3 - (2), ClO 4 - (3)), {[Ag2(bib)2(NO2)](NO2) · 19/8H2O}n (4) and {[Ag2(bib)2](V4O12)0.5 · 3H2O · 2MeCN}n (5) were generated. In compounds 1, 4 and 5, bib ligand adopts trans configuration and twists around the Ag–Ag axis, giving rise to single-stranded helical structure with short adjacent Ag⋯Ag distances of 3.56, 3.56, 3.50 and 3.63 A, respectively. Compounds 2 and 3 are 1D coordination polymers fusing the [2 + 2] metallocycle [Ag2(bib)2]2+, in which bib ligand exhibits in cis configuration and the metallocycles have longer Ag⋯Ag distances of 8.52 A in 2 and 8.61 A in 3 along with the strong intracyclicπ–π interactions between phenyl groups. Cis and trans configurations of bib coexist in solution and crystallize in complexes 1 and 2 in the solid state in the presence of en or pn. The solution of 1 and 2 can be converted into 3 via the addition of the bulky ClO 4 - counter anion or into 4 through introduction of the competing ligand/conuterion NO 2 - .

A new anion sensor [Ru(bpy)2(H2biim)](PF6)2 (1) (bpy = 2,2'-bipyridine and H2biim = 2,2'-biimidazole) has been developed, in which the Ru(II)-bpy moiety acts as a chromophore and the H2biim ligand as an anion receptor via hydrogen bonding. A systematic investigation shows that 1 is an eligible sensor for various anions. It donates protons for hydrogen bonding to Cl-, Br-, I-, NO3-, HSO4-, H2PO4-, and OAc- anions and further actualizes monoproton transfer to the OAc- anion, changing color from yellow to orange brown. The fluoride ion has a high affinity toward the N-H group of the H2biim ligand for proton transfer, rather than hydrogen bonding, because of the formation of the highly stable HF2- anion, resulting in stepwise deprotonation of the two N-H fragments. These processes are signaled by vivid color changes from yellow to orange brown and then to violet because of second-sphere donor-acceptor interactions between Ru(II)-H2biim and the anions. The significant color changes can be distinguished visually. The processes are not only determined by the basicity of anion but also by the strength of hydrogen bonding and the stability of the anion-receptor complexes. The design strategy and remarkable photophysical properties of sensor 1 help to extend the development of anion sensors.

Two manganese(II) coordination polymers, [Mn2(bpt)(pa)2(N3)]n [1; Hpa = picolinic acid, Hbpt = 3,5-bis(2-pyridyl)-4H1,2,4-triazole] and [Mn3(ina)2(pa)2(N3)2]n (2; Hina = isonicotinic acid), have been synthesized by solvothermal treatment, in which the ligands bpt and pa were generated in situ by cyclocondensation and hydrolysis of 2-pyridylamidrazone, respectively. In 1, each binuclear subunit [Mn2(bpt)(N3)] bridged by bpt and N3 – ligands is interlinked to four adjacent subunits via four tridentate pa ligands into a diamondoid 3D network, which shows spin-canting magnetism arising from

A new fluorescent chemosensor 5-( p - N , N ′-bis(2-pyridyl)amino)phenyl-10,15,20-tris( p -methoxyphenyl)porphyrin zinc has been designed and synthesized by the Ullmann-type coupling. It displays high selectivity for Cu 2+ ion and exhibits fluorescence quenching upon binding of Cu 2+ ion with an “on–off” type fluoroionophoric switching property, and its fluorescence can be revived by addition of EDTA disodium solution.

Four dimeric and polymeric coordination compounds [Zn 2 (bimb) 2 (pdc) 2 ]·6H 2 O ( 1 ), [Cd 2 (bimb) 2 (tp) 2 ]·H 2 O ( 2 ), [Cd(bimb)(ada)] ( 3 ) and [Co(bimb)(ada)] ( 4 ) (bimb, 4,4′-bis(imidazol-1-ylmethyl)biphenyl; pdc, pyridine-2,6-dicarboxylate; tp, terephthalate and ada, adipate) have been synthesized under hydrothermal conditions. Complex 1 is a discrete dinuclear metallomacrocycle featuring a 34-membered ring, in which the flexible bimb ligand acts as syn -conformation. While complexes 2 – 4 are 3D network structures connected by bimb and dicarboxylate ligands, the bimb ligand displays anti -confromation.

The facile and effective one-pot solvothermal syntheses of 3,5-disubstituted 1,2,4-triazole and its derivatives (substituted group = alkyl, aryl, and pyridyl) through cyclocondensations of organonitriles and hydrazine hydrate in the absence/presence of metal salts have been established. By control of the solvothermal conditions and/or the addition of counteranions, different intermediates and final products were derived from various organonitriles, in which an intermediate N,N'-bis(picolinamide)azine (H4bpa) has been successfully trapped in its neutral manganese(II) complexes. A systematical study shows that, after the initial formation of 2-pyridylamidrazone from 2-cyanopyridine and hydrazine, two reaction paths are involved in the formation of 1,2,4-triazoles: via the formation of 3,6-bis(2-pyridyl)-1,2-dihydro-1,2,4,5-tetrazine and H4bpa as intermediates. The tetrazine and H4bpa paths are preferred in the absence and presence of metal ions, respectively. In the presence of metal ions, metal ion binding can stabilize the tautomers, enhance the nucleophilic reactivity of the imino C atom, and inhibit the tautomerization of H4bpa, hence leading to the formation of 1,2,4-triazolates or H4bpa in complexed forms. The in situ cyclocondensation reactions of 2-pyridylamidrazone and carboxylate into asymmetric 3,5-disubstituted 1,2,4-triazolates under solvothermal conditions have also been observed for the first time. Crystal structures of the crystalline metal complexes have been obtained, including dinuclear [Mn2(bpt)2Cl2(H2O)2] (1) and [Mn2(bpt)2(SCN)2(H2O)2] (3; Hbpt = 3,5-bis(2-pyridyl)-4H-1,2,4-triazole), tetranuclear [Mn4(H3bpa)2(mpt)4(N3)2].2H2O (5; Hmpt = 3-methyl-5-(2-pyridyl)-1H-1,2,4-triazole), [Mn4(H3bpa)2(pt)4(N3)2].2C2H5OH (6; Hpt = 5-(2-pyridyl)-1H-1,2,4-triazole), and [Mn4(H3bpa)4(SCN)4].2C2H5OH (7), as well as helical [Cu(bpt)] (2). Among them, 7 is the first example of a neutral tetranuclear [2 x 2] grid manganese(II) complex. Both 5 and 7 exhibit antiferromagnetic interactions.

A new class of platinum(II) acetylide complexes with urea group, [Pt(tBu3tpy)(CCC6H4-4-NHC(O)NHC6H4-4-R)](OTf) (tBu3tpy = 4,4′,4′′-tri-tert-butyl-2,2′:6′,2′′-terpyridine; R = H (3a), Cl (3b), CF3 (3c), and NO2 (3d)), has been synthesized and characterized. The crystal structures of 3a, 3a·DMF·THF, 3b·CH3CN, and 3c·CH3CN have been determined by X-ray diffraction. Upon excitation at λ > 380 nm, the solid samples of complexes 3a–3d show orange light at 298 K. The anion binding properties of complexes 3a–3d have been studied by UV-vis titration experiments in CH3CN and DMSO. In general, the log K values of 3a–3d with the same anion in CH3CN depend on the substituent R on the acetylide ligand of 3a–3d and follow this order: R = NO2 (3d) > CF3 (3c) > Cl (3b) > H (3a). For the same complex with different anions, the log K values are in the following order: F− > OAc− > Cl− > Br− ≈ HSO4− ≈ NO3− > I−, which is in accordance with the decrease in the basicity of anions. Complex 3d with NO2 group shows a dramatic colour change towards F− in DMSO, allowing the naked eye detection of F−.

The preparation of chiral 2-(alkylsulfinyl)phenol compounds by enantioselective coordination-oxidation of the thioether ruthenium complexes with a chiral-at-metal strategy has been developed. The enantiomerically pure sulfoxide complexes Δ-[Ru(bpy)2{(R)-LO-R}](PF6) (bpy is 2,2'-bipyridine, HLO-R is 2-(alkylsulfinyl)phenol, R = Me (Δ-1a), Et (Δ-2a), iPr (Δ-3a), Bn (Δ-4a), and Nap (Δ-5a)) and Λ-[Ru(bpy)2{(S)-LO-R}](PF6) (R = Me (Λ-1a), Et (Λ-2a), iPr (Λ-3a), Bn (Λ-4a), and Nap (Λ-5a)) have been synthesized by the reaction of Δ-[Ru(bpy)2(py)2](2+) or Λ-[Ru(bpy)2(py)2](2+) with the prochiral thioether ligands 2-(alkylthio)phenol (HL-R), followed by enantioselective oxidation with m-CPBA as oxidant. The X-ray crystallography was used to verify the stereochemistry of ruthenium complexes and sulfur atoms. The configurations of the ruthenium complexes are stable during the coordination and oxidation reactions. Moreover, the chiral sulfoxide ligands are enantioselectively generated by controlling of the configuration of ruthenium centers in the course of oxidation reaction. That is, the Λ configuration at the ruthenium center generates the S sulfoxide ligand; on the contrary, the Δ configuration of the ruthenium complex originates the R sulfoxide ligand. Acidolysis of Λ-[Ru(bpy)2{(R)-LO-R}](PF6) and Δ-[Ru(bpy)2{(S)-LO-R}](PF6) complexes in the presence of TFA-MeCN afforded the chiral ligands (R)-HLO-R and (S)-HLO-R in 96-99% ee values, respectively. Importantly, the chiral ruthenium complexes can be recycled as Δ/Λ-[Ru(bpy)2(MeCN)2](PF6)2 and reused in a next reaction cycle with complete retention of the configurations at ruthenium centers.

Cocrystallizations of melamine (MA) with 1,5-naphthalenedisulfonic acid (H2NDA) from water in different molar ratios (2:1, 4:1, and 8:1) offer [(HMA+)2(NDA2-)]·4H2O (1), [(HMA+)2(MA)2(NDA2-)]·8H2O (2), and [(HMA+)2(MA)2(NDA2-)]·10H2O (3), respectively. Among them, sulfonic protons are transferred to the triazine nitrogen atoms of MA, furnishing hydrogen-bonded anionic [(NDA2-)·H2O]∞ chains. In 1, the adjacent HMA+ cations form cationic (HMA+)∞ ribbons via pairs of N−H···N hydrogen bonds ( (8) synthon), and the ribbons connect to each other through NDA2- anions as well as lattice water molecules via hydrogen bonds and C−H···π, π···π, and electrostatic interactions to form a 3D structure. In 2 and 3, only half of the MA molecules are protonated, resulting in cationic (MA·HMA+)∞ ribbons via N−H···N hydrogen bonds. In 2, hydrophilic channels (size 3.9 × 6.1 A2) enclosed by the NDA2- anions and (MA·HMA+) cations are found to host a pair of zigzag water chains, which are interlinked through sulfonate oxygen ato...

The new complex [Cd2(bpa)2Cl4]·6 H2O [bpa = N,N'-bis(picolinamide)azine] has been synthesized in which each bpa ligand is twisted into a spiral-like conformation and the two CdII ions are ligated by two bpa ligands to form a double-stranded binuclear helicate. Unprecedented water chains featuring cyclic water tetramers composed of three independent water molecules are trapped by [Cd2(bpa)2Cl4] double helicates by hydrogen bonds. The binuclear chiral helicates are interlinked into homochiral layers by hydrogen bonds with the water tapes. The layers are alternately stacked in a heterochiral fashion to yield the final racemic structure. The complex shows an endotherm at 65.7 °C in the DSC due to loss of water molecules, giving an enthalpy value of 47 kJ mol–1 per water molecule. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Two new coordination polymers [Cd(tdc)(bpy)(H2O)]n (1) and [Cd(tdc)(phen)]n (2) (H2tdc = thiophene-2,5-dicarboxylic acid, bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesized under hydrothermal condition. Their crystal structures have been established by X-ray single-crystal diffraction. Complex 1 crystallizes in the orthorhombic space group Fdd2 with a = 14.757(7), b = 45.38(2), c = 10.518(5) A, V = 7044(6) A3, Z = 16; 2 in the monoclinic space group P21/c with a = 7.262(1), b = 21.970(2), c = 10.051(1) A, β = 105.01(1)°, V = 1548.8(2) A3, Z = 4. Both of them are double-stranded chains and further assembled into three-dimensional networks by π-π stacking interactions. 1 and 2 are stable in air, and show blue photoluminescence at 415 nm and 410 nm, respectively.

This review provides an overview on the crystal structures and properties of metal carboxylate coordination compounds with 2,2′-bipyridyl-like ligands reported in the past 4 years, which exhibit interesting structural features. This covers coordination polymers in one, two and three dimensions, as well as molecular architectures assembled by hydrogen-bonding and/or π–π stacking interactions from low-dimensional entities to higher-dimensional supramolecular architectures.

A new one-dimensionally neutral coordination polymer, namely {[Pb(phen)2(ox)]·5H20}n (phen = 1, 10-phenanthroline, ox = oxalate) (1), has been synthesized under hydrothermal condition and characterized by X-ray crystallography. Complex 1 crystallizes in the orthorhombic space group Pban (No. 50) with a = 19.358(2), b = 6.8135(6), c = 9.7015(8)A, V = 1279.6(2)A3, and Z = 2. Each Pb(II) atom is eight-coordinated in a square-antiprismatic D4d geometry by four nitrogen atoms from two phen groups and four oxygen atoms from two ox ligands. The polymeric chains further constructed into a three-dimensional network via strong π—π stacking interactions and hydrogen bonds. The complex exhibits intense blue photoluminescence with an emission maximum at 403 nm at room temperature. Hydrothermale Synthese und Kristallstruktur eines neuen polymeren oxalatverbruckten Blei(II)-Komplexes {[Pb(phen)2(ox)]·5H20}n (phen = 1, 10-Phenanthrolin, ox = Oxalat) Eine neue eindimensional-polymere, neutrale Koordinationsverbindung, {[Pb(phen)2(ox)]·5H20}n (phen = 1, 10-Phenanthrolin, ox = Oxalat) (1), wurde unter hydrothermalen Bedingungen synthetisiert und durch Rontgen-Kristallstrukturanalyse charakterisiert. 1 kristallisiert orthorhombisch, Raumgruppe Pban (No. 50) mit a = 19.358(2), b = 6.8135(6), c = 9.7015(8)A, V = 1279.6(2)A3, Z = 2. Jedes Blei(II)-Atom ist achtfach koordiniert in quadratisch-antiprismatischer D4d-Geometrie von vier Stickstoffatomen der zwei Phen-Gruppen und vier Sauerstoffatomen der zwei Oxalat-Liganden. Die polymeren Ketten bilden durch starke π—π-Wechselwirkungen und Wasserstoffbruckenbindungen ein dreidimensionales Gerust. Der Komplex zeigt intensiv-blaue Photolumineszens mit einem Emissionsmaximum von 403 nm bei Zimmertemperatur.

Two new linear and V-shaped tetradentate ligands, namely 1,4-bis(2-hexahydropyrimidyl)benzene (L) and 1,3-bis(2-hexahydropyrimidyl)benzene (L′), and their silver(I) complexes, [Ag2L(μ-ONO2)](NO3) · 2H2O (1), [Ag2L(μ-pn)](NO3)2 (2), [Ag2L(μ-pn)](ClO4)2 (3) and [Ag4L′2(H2O)](NO3)4 · 5H2O (4) (pn=1,3-diaminopropane) have been synthesized in situ and structurally characterized by single-crystal X-ray diffraction. 1 and 2 were obtained from the same reaction solution but different crystallization conditions. 1 is an one-dimensional chain featuring cuboid tetranuclear silver(I) units interconnected through monoatomic nitrate bridges. Both 2 and 3 are ribbon-like helical compounds in which each L ligand acts in a tetradentate bridging mode to interconnect four metal atoms, and each pn ligand functions in a bidentate bridging mode to link a pair of metal atoms. 4 shows a truncated square-pyramidal tetranuclear motif arose by the V-shaped L′ ligand. Close Ag⋯Ag separations (2.901–2.939 A) assisted by bis(hexahydropyrimidine) bridges were observed in 1 and 4, indicating metal–metal interactions. Photoluminescence of 1–4 has also been observed in the solid state and solution at room temperature and low temperature, respectively.

Two new neutral polymeric layer compounds, [Cu3(bpy)2(Hip)2(ip)2] (1) and [Cu3(phen)2(Hip)2(ip)2] (2) (bpy = 2, 2′-bipyridine, phen = 1, 10-phenanthroline, ip = isophthalate), have been synthesized under hydrothermal conditions and characterized by X-ray crystallography. Complex 1 crystallizes triclinic, P1¯ (No. 2), a = 10.352(5), b = 10.859(6), c = 11.602(6)A, α = 83.25(1), β = 84.71(1), γ = 66.19(1)°, V = 1183.5(11)A3, Z = 1; 2 triclinic, P1¯ (No. 2), a = 10.375(1), b = 10.668(1), c = 11.758(1)A, α = 83.179(2), β = 86.228(2), γ = 71.187(2)°, V = 1222.7(2)A3, Z = 1. The complexes consist of trinuclcear copper units that are bridged via two ip ligands forming zigzag polymeric chains. These chains are further extended into layers via aromatic π-π interactions as well as hydrogen bonds between the free carboxyl groups and carboxylates. Synthese und strukturelle Charakterisierung von zwei neuen 2D-Isophthalatverbruckten Kupfer(II)-Polymeren mit Cu3-Einheiten Zwei neue polymere Schichtverbindungen, [Cu3(bpy)2(Hip)2(ip)2] (1) und [Cu3(phen)2(Hip)2(ip)2] (2) (bpy = 2, 2′-bipyridin, phen = 1, 10-phenanthrolin, ip = isophthalat), wurden unter hydrothermalen Bedingungen synthetisiert und mittels Rontgen-Kristallstrukturanalyse charakterisiert. Complex 1 kristallisiert triklin, P1¯ (No. 2), a = 10.352(5), b = 10.859(6), c = 11.602(6)A, α = 83.25(1), β = 84.71(1), γ = 66.19(1)°, V = 1183.5(11)A3, Z = 1; 2 triklin, P1¯ (No. 2), a = 10.375(1), b = 10.668(1), c = 11.758(1)A, α = 83.179(2), β = 86.228(2), γ = 71.187(2)°, V = 1222.7(2)A3, Z = 1. Die Komplexe bestehen aus dreikernigen Kupfer-Einheiten, die uber zwei ip-Liganden unter Bildung von polymeren zick-zack-Ketten verbruckt sind. Diese Ketten bilden Schichten uber aromatische π-π-Wechselwirkungen und Wasserstoffbruckenbindungen zwischen den freien Carboxyl-Gruppen und Carboxylaten.

Four novel aqua-bridged dinuclear complexes with a formula M 2 (μ-H 2 O)(μ-OAc) 2 (Im) 4 (OAc) 2 (where Im=imidazole, M=Mg 2+ 1 , Mn 2+ 2 , Ni 2+ 3 and Co 2+ 4 ) have been synthesized and characterized. Complexes 1 , 2 and 3 have been characterized by X-ray crystallography. Two M 2+ ions are bridged by an aqua molecule and two carboxylate anion with M⋯M=3.635–3.777 A, M–OH 2 =2.109–2.246 A and M–OH 2 –M=114.4–119.0°, respectively. Each complex is further stabilized by two intramolecular hydrogen bonds between the hydrogens of the bridging aqua and the oxygens of the terminal monodentate acetates with a distance of O⋯O=2.6 A. The terminal monodentate acetates display ‘reversed’ C–O distances, namely the C–O(free) distances are actually longer than the C–O(coordinating) distances. This abnormal geometry of a monodentate carboxylate would be caused by the strong ‘pulling effect’ on the terminal carboxylates by intra- and intermolecular hydrogen bonds. The O–H stretching vibration of the bridging water was identified at ca. 2328 cm −1 in IR spectra based on the deuterium isotope shift. The solid state 13 C and 15 N NMR spectra of 1 displayed two sets of peaks for acetate and Im ligands, respectively, consistent with the presence of two types of coordination modes of acetate and the two symmetrically non-equivalent Im as revealed by X-ray structure. 15 N chemical shift of NH in Im ligands underwent about 6 ppm downfield shift due to its involvement in an intermolecular hydrogen bond.

Two di- and a tetranuclear zinc−carboxylate complexes with different coordination modes, [Zn2L(μ1,3-OAc)2](ClO4) (1), [Zn2L(μ1,3-Pro)2](ClO4) (2), and [Zn2L(μ1,1-HCO2)(μ1,3-HCO2)]2(ClO4)2 (3) (wher...

Two structurally related complexes [Ru(phen)2taptp]2+ (1) and [Ru(phen)2dptatp]2+ (2), where taptp is 4,5,9,18-tetraazaphenanthreno[9,10-b]triphenylene and dptatp is 2,3-diphenyl-1,4,8,9-tetraazatriphenylene, were synthesized and characterized by elemental analyses and 1H NMR. The spectroscopic and electrochemical properties of complexes 1 and 2 were also examined. Both complexes can luminesce in organic solvent but are quenched in water to different extents. The interaction of the complexes with calf thymus DNA was studied by absorption and emission spectra, as well as viscosity and lifetime measurements. All the data indicate that both complexes bind with double-stranded calf thymus DNA via intercalative mode. Unlike its analog [Ru(bpy)2taptp]2+, [Ru(phen)2taptp]2+ shows negligible luminescence in water buffer but bright luminescence on binding to DNA, enabling it to be a sensitive probe for DNA conformation.

The reactions of divalent metal acetate (M=Cd II , Co II , Cu II , Mn II and Ni II ) with 2,2′-bipyridine (bpy) were systematically observed at a ratio of 1:1 in methanol solution. Three kinds of complexes were isolated: mononuclear [Ni(bpy)(OAc) 2 (H 2 O) 2 ] ( 6 ), binuclear [Cd 2 (bpy) 2 (OAc) 4 (H 2 O) 2 ] ( 7 ) and [Cu 2 (bpy) 2 (OAc) 4 ]·2H 2 O ( 8 ), linear trinuclear [M 3 (bpy) 2 (OAc) 6 ] (M=Co II ( 11 ) and Mn II ( 12 )). When 1.5 equivalent NaClO 4 was added to the reaction solution, respectively two kinds of complexes were obtained: mononuclear [M(bpy) 2 (OAc)](ClO 4 )· n H 2 O (M=Cd II ( 1 ), Co II ( 2 ), Mn II ( 3 ) and Ni II ( 4 )) and binuclear [M 2 (bpy) 2 (μ-OAc) 3 ](ClO 4 ) (M=Cu II ( 9 ) and Zn II ( 10 )). The structures of complexes 1 , 7 and 11 were determined by X-ray diffraction analysis. Complex 7 is the first example of a dicadmium complex linked by two monoatomic bridging acetate ligands with the longest distance of 3.380(4) A between the dangling acetate oxygen and metal atoms. Several novel structural features in complex 7 have been found in comparison with the monodentate bridging carboxylate with no or only weak interaction between the dangling acetate oxygen atom and metal atom. The structure of complex 11 consists of linear trinuclear molecules; each pair of cobalt atoms are bridged by three acetate groups, two of them acting as bidentate bridging mode and the third as a monoatomic bridge plus bidentate chelating mode, at a distance of 3.459 A. The central cobalt(II) coordinates by six oxygen atoms from six different acetate groups, and the terminal ones have a distorted environment of four oxygen atoms and two nitrogen atoms from a bpy ligand.

Two new ligands containing an intramolecular hydrogen bond, 2-(2-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline (HPIP) and 2-(2-hydroxy-1-naphthyl)imidazo[4,5-f][1,10]phenanthroline (HNAIP), and their complexes [Ru(bpy)2(HPIP)](PF6)2·H2O (1) and [Ru(bpy)2(HNAIP)](PF6)2·2H2O (2) (bpy=2,2′-bipyridine) have been synthesized and characterized by UV–Vis, IR, 1H NMR, and mass spectra. The electrochemical behaviors of the two complexes were studied by cyclic voltammetry. The binding of the two complexes with calf thymus DNA has been investigated by absorption, luminescence titrations, steady-state emission quenching, and viscosity measurements. The results suggest that complex 1 intercalates into DNA base pairs via the ligand HPIP, while complex 2 binds with DNA by partially intercalating the ligand HNAIP. Complex 1 shows higher affinity to DNA than complex 2. The intrinsic binding constants K for complexes 1 (6.5±0.3×105 M−1) and 2 (8.3±0.4×104 M−1) together with [Ru(bpy)2PIP]2+ (4.7±0.2×105 M−1, PIP=2-phenylimidazo[4,5-f][1,10]phenanthroline) were determined by absorption titration.

Two monomeric zinc complexes, [Zn(H2biim)2(H2O)2](OAc)2·OHCH2CH2OH (H2biim=2,2′-biimidazole) (1) and [Zn(bipy)2(H2O)(CF3CO2)](ClO4) (bipy=2,2′-bipyridine) (2), have been synthesized and characterized by NMR and single-crystal structural analysis. The zinc ions in both complexes are coordinated in a distorted N4O2 octahedral geometry: the zinc ion in complex 1 is surrounded by two aqua [Zn–O 2.150 (3) A] and two H2biim ligands (Zn–N 2.150 A), the acetate groups act as counter-anions and form hydrogen bonds with H2biim; the zinc ion in 2 is ligated by two bipy ligands (Zn–N 2.144 A), one aqua molecule [Zn–O 2.148(2) A] and one monodentate carboxylate [Zn–O 2.154(2) A]. In both complexes, the aqua ligand forms strong donor hydrogen bonds with the hydroxyl or carboxylate groups, being analogous to those found for the active sites of several zinc enzymes.

[Ru(bipy)2(5-R-phen)](ClO4)2 complexes have been prepared, where bipy=2,2′- bipyridine, phen=1,10-phenanthroline, and R=H, Me, NO2 or NH2. The influence of the different 5- substituted phen on the electron delocalization and ligand-ligand interactions have been investigated by solution n.m.r.. The ligand- ligand interaction has also been observed in the solid state by determining the single crystal structure of [Ru(bipy)2(5- NO2-phen)](ClO4)2. The strong steric interaction between the polypyridyl ligands was relieved neither by the elongation of Ru–N bonds (2.055–2.086A) nor by increase of N–Ru–N bite angles (77.8–79.4°), but rather by distortion of the coordination sphere by forming specific angles (δ=2.0, 3.2 and 4.2°) between the polypyridyl ligand planes and coordination planes (N–Ru–N), and larger torsion angles (5.8 and 8.2°) between the two pyridine rings for each bipy.

A novel ruthenium(II) complex of dipyridophenazine (DPPZ) with the ancillary ligand imidazole[4,5- f ] [1,10]phenanthroline (IP), [Ru(IP) 2 (DPPZ)] (PF 6 ) 2 , has been synthesized and characterized by elemental analysis, 1D and 2D 1 H NMR, fast-atom bombardment mass spectra (FABMS), electronic spectroscopy and cyclic voltammetry. The DNA-binding properties of the complex were studied by spectroscopic methods. The intrinsic binding constant, K =2.1 × 10 7 M −1 , of the complex to calf thymus DNA has been determined by absorption titration in 5 mmol dm −3 Tris-HCl, 50 mmol dm −3 NaCl buffer (pH 7.0). The excited state lifetimes and luminescence quenching with [Fe(CN) 6 ] 4− as the quencher in the presence of DNA were also tested and mono-exponentiality was observed for the emission decay curves. Viscosity measurements together with the optical titrations unambiguously proved that the complex bound with DNA intercalatively and that the binding affinity to DNA was several times larger than that of the parent complex [Ru(bpy) 2 (DPPZ)] 2+ .

Two compounds, [Ag(2,4‘-bpy)]NO3 (1) and [Ag(2,4‘-bpy)]ClO4 (2), were obtained from self-assembly of AgX (X = NO3-, ClO4-) with 2,4‘-bipyridine (2,4‘-bpy). 1 crystallizes in the orthorhombic space group Pbca, with a = 11.2884(7) A, b = 11.3981(10) A, c = 16.5299(13) A, and Z = 8, while 2 crystallizes in the monoclinic space group P21/c, with a = 10.6361(4) A, b = 9.9896(4) A, c = 11.2661(6) A, β = 98.527(4)°, and Z = 4. Both complexes consist of helical [Ag(2,4‘-bpy)]∞ chains that are surrounded by nitrate or perchlorate counterions. Adjacent helical chains are racemic. The AgI atom is linked to two nitrogen atoms of the 2-pyridyl and 4‘-pyridyl groups from two different 2,4‘-bpy ligands as well as to the oxygen atom of the counterion. In 1, another oxygen atom of the counterion is weakly coordinated to the AgI atom of an adjacent chain, thus bridging the helical chains into a wavy 2-D network structure, whereas in 2, adjacent helical chains are linked by the weak ligand-unsupported metal−metal interactio...

Two one dimension copper (II) polymer chain complexes with an identical molecular formula, [Cu (dien) (OAc) ] n (ClO4) n, but different stuctural features were synthesized through the reaction of Cu2 (OAc) 4 · 2H2O with M (dien) 2 (ClO4) 2 (M = Cu2, Ni2 and Zn2 ; dien = diethylenetriamine) . In complex 1, the geometry at each Cu (II) ion is a distorted octahedron (4+2) (D. K. Towle, et al. Inorg. Chem. 1988, 27, 394–399) ; while in complex 2, that is pentacoordinate and best described as a distorted trigonal bipyramid. The acetate groups act as monodentate bridging mode in 1, but as single syn-anti bridging fashion (Cu — O = 2.008 (10) and 2.062 (11) A) in 2. These provide a good example for the suggested pathway in the ‘‘carboxylate shift’’. The isomer can also be diagnosed by FT-IR and FT-Raman spectroscopies, and X-ray powder diffraction.

In the presence of guest 2,4'-bpy molecules or under acidic conditions, three compounds, [Cd(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (1), [Zn(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(2).(2,4'-bpy)(2).H(2)O (2), and [Cu(4,4'-bpy)(2)(H(2)O)(2)](ClO(4))(4).(4,4'-H(2)bpy) (3), were obtained from the reactions of the metal salts and 4,4'-bpy in an EtOH-H(2)O mixture. 1 has a 2-D square-grid network structure, crystallizing in the monoclinic space group P2/n, with a = 13.231(3) A, b = 11.669(2) A, c = 15.019(3) A, beta = 112.82(3) degrees, Z = 2; 2 is isomorphous with 1, crystallizing in the monoclinic space group P2/n, with a = 13.150(3) A, b = 11.368(2) A, c = 14.745(3) A, beta = 110.60(3) degrees, Z = 2. The square grids superpose on each other into a channel structure, in which each layer consists of two pairs of shared edges, perfectly square-planar with an M(II) ion and a 4,4'-bpy at each corner and side, respectively. The square cavity has dimensions of 11.669(2) x 11.788(2) and 11.368(2) x 11.488(2) A for 1 and 2, respectively. Every two guest 2,4'-bpy molecules are clathrated in each hydrophobic host cavity and are further stabilized by pi-pi stacking and hydrogen bonding interactions. The NMR spectra clearly confirm that both 1 and 2 contain 4,4'-bpy and 2,4'-bpy molecules in a 1:1 ratio, which have stacking interaction with each other in the solution. 3 crystallizes in the orthorhombic space group Ibam, with a = 11.1283(5) A, b = 15.5927(8) A, c = 22.3178(11) A, Z = 4. 3 is made up of two-dimensional square [Cu(4)(4,4'-bpy)(4)] grids, where the square cavity has dimensions of 11.13 x 11.16 A. Each [4,4'-H(2)bpy](2+) cation is clathrated in a square cavity and stacks with one pair of opposite edges of the host square cavity in an offset fashion with the face-to-face distance of ca. 3.95 A. Within each cavity, the [4,4'-H(2)bpy](2+) cation forms twin three-center hydrogen bonds with two pairs of ClO(4)(-) anions. The results suggest that the guest 2,4'-bpy molecules and protonated [4,4'-H(2)bpy](2+) cations present in the reaction systems serve as structure-directing templates in the formation of the crystal structures and exclude self-inclusion of the networks having larger square cavities.

Four new ruthenium(II) complexes [Ru(bpy)2(TMBiimH2)](ClO4)2 (Ru-5; bpy is 2,2'-bipyridine and TMBiimH2 is 4,5,4',5'-tetramethyl-2,2'-biimidazole), [Ru(bpy)2(L1H2)](ClO4)2·H2O (Ru-6; L1H2 is 4,5-dimethyl-2-(N,N-diacetyl)carboximidamide-1H-imidazole), [Ru(bpy)2(L2H2)](ClO4)2 (Ru-7; L2H2 is N(1),N(1),N(2),N(2)-tetrakis(acetyl)ethanediimidamide), and [Ru(phen)2(TMBiimH2)](ClO4)2 (Ru-8; phen is 1,10'-phenanthroline) have been synthesized and characterized. Their photophysical and electrochemical properties have been studied and compared to the previously reported [Ru(bpy)2(BiimH2)](PF6)2 (Ru-1), [Ru(bpy)2(BbimH2)](PF6)2 (Ru-2), [Ru(bpy)2(DMBbimH2)](PF6)2 (Ru-3), and [Ru(bpy)2(TMBbimH2)](PF6)2 (Ru-4). Under irradiation with either sunlight or household light in atmosphere, Ru-5 reacts with molecular oxygen to produce Ru-6 in an acetonitrile solution with a relatively high concentration and Ru-7 in a methanol or dilute acetonitrile solution, respectively. The mechanism studies show that singlet oxygen is the reactive oxygen species in the ring-opening reaction and the photooxidation reaction is solvent- and concentration-dependent. The photoreaction product Ru-6 is an intermediate, which has been isolated and structurally characterized by single-crystal X-ray diffraction. Ru-6 is stable in the solid state and an acetonitrile solution with a high concentration, but can be further oxidized to Ru-7 in a methanol or dilute acetonitrile solution.