A Silver Complex of 6,7-Dicyanodipyridoquinoxaline:π-Stacking Interactions and Luminescence

The reaction of 6,7-dicyanodipyridoquinoxaline （DICNQ） with AgNO3 in a 1：1 molar ratio by solution method gave a new complex [Ag（DICNQ）2]NO3 1. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the space group Ibca of orthorhombic system with eight formula units in a cell. Crystal data for 1： a = 15.7055（17）, b = 18.411（2）, c = 20.680（2）A, V = 5979.7（11）A3, Z = 8, C32Hl2AgN13O3, Mr = 734.42, Dc = 1.632 g/cm3, μ= 0.734 mm-1, F（000） = 2928, S = 1.023 and T= 293（2） K. The final R = 0.0659 and wR = 0.1927 for 2118 observed reflections with I 〉 2σ（I）, and R = 0.0801 and wR = 0.2196 for all data. The complex builds up a packing structure by π-π stacking interactions and shows a luminescent feature.

A New Cadmium(Ⅱ) Coordination Polymer Extended through Hydrogen Bonds and π-π Stacking Interactions: Synthesis and Photoluminescence Property

A new coordination polymer, {[Cd(OPY)(tdc)(HO)]·H2 O}n(OPY = 4,4?-(oxybis(4,1-phenylene))dipyridine, H2 tdc = thiophene-2,5-dicarboxylic acid), has been synthesized hydrothermally based on a V-shaped ligand OPY. The structure was fully characterized by elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction analysis. In1, two OPY ligands and one water molecule acted as terminal ligands coordinating to Cdcation to form [Cd(OPY)HO]units, which are then linked by tdc2-ligands to generate a one-dimensional chain. Every two adjacent chains linked by extensive O–H···O hydrogen bonds constitute one-dimensional double-chains, and such chains are extended into two-dimensional layers via O–H···N hydrogen bonds. These layers are further connected to form a three-dimensional supramolecular architecture via π-π stacking interactions. In addition, the thermal stability and solid state fluorescence property of 1 were also investigated.

Thermal Stability Improved by π–π Stacking Interactions: Synthesis, Crystal Structure and Thermal Decomposition of Sodium Nitroformate

An energetic salt, sodium nitroformate （NaNF）, was synthesized and characterized by elemental analysis, IR and UV spectra, and its crystal structure was first determined by single crystal X-ray diffraction. The structure exhibits two types of π-π stacking interactions between the nitroformate anions, i e, the parallel-displaced and T-shaped confgurafions. Furthermore, the thermal decomposition mechanism was investigated by DSC, TG-DTG and FTIR techniques. The kinetic parameters of the thermal decomposition were also calculated by using Kissinger＇s and Ozawa-Doyle＇s methods. The results show that NaNF has a good thermal stability, which is attributed to the π-π stacking interactions.

Metastability of π-π stacking between the closed-shell ions of like charges

Planar cations or anions can form stacks in crystals or solutions,where the surrounding or environment plays a decisive role as demonstrated in previous studies.However,it remains unclear whether these counterintuitive interactions possess any inherent stability or are thoroughly repulsive if the constraint of environment is removed.In this work,we explored the inherent stability ofπ-πstacking between closed-shell ions of like charges with prototypes derived from experimental studies.The inherent metastability was identified by the characteristic local minima and the transition states preventing their dissociation and verified by ab initio molecular dynamics(AIMD)simulations.The nature of involved interactions was deciphered with the energy decomposition approach based on the block-localized wavefunction method(BLW-ED).Like the conventional neutralπ-πstacking interactions,electron correlation is the most attractive energy component.But it is overturned by the Coulombic repulsion between net charges for all modes of dimerization,resulting in the overall repulsive inter-cation or anion in-teractions.Contributions from van der Waals interactions were also observed in the reduced density gradient analysis.The origin of the metastability was elucidated by examining the contributions of individual physical factors to the well-depths.The inherent metastability originates from the electron correlation,which dramatically increases due to the enhanced overlap between ions from a transition state to its corresponding minimum.

Intramolecular stacking interaction in mixed-ligand complexes containing ATP4-and aromatic N-heterocyclic ligands

The stability constants of the binary ML2+ and ternary M(ATP)L2? complexes, where L=Iq (isoquinoline) or BIm (benzimidazole) and M=Zn2+ or Cd2+, have been determined by potentiometric pH titration in aqueous solution at I=0.1 mol/L (NaClO4), T=25°C. The stability of the ternary complexes characterized by ΔlogKM=logKM(ATP)LM(ATP)L- logKMML corresponding to the equilibrium M(ATP)2? + ML2+ = M(ATP)L2? + M2+ in higher than what would be expected on statistical grounds. The increase may be related to the stacking interaction between the aromatic ring of the ligands L and the purine moiety of ATP4–. 1H NMR studies of Zn2+/ATP4?/L confirm the presence of stacking in the ternary complexes. It is concluded that the strength of the intramolecular stacking interaction ia dependent on the structure of the aromatic ring of the ligand L and the formation of a metal ion bridge. Possible implications an discussed briefly.

Crystal Structure of 2,6-Dihistidine Dimethyl Ester Pyridine Acylamine Monohydrate

The crystal structure of the title compound,C21H25N7O7,has been determined in the orthorhombic space group C222（1） with a=8.993（10）,b=12.149（14）,c=22.20（2）A and Z=4.There exist intramolecular C-H…O and N-H…N hydrogen bonds in the title crystal structure.The intermolecular N-H…N and C-H…O hydrogen bonds together with π-π stacking interactions（face-to-face） link the molecules into an infinite three-dimensional supramolecular network.

Solvothermal Synthesis and Crystal Structure of a 1D Helical-chain Cobalt(II) Complex Containing (Quinolin-8-yloxy)acetate

The cobalt（II） complex with （quinolin-8-yloxy）acetate, [CoCl（C11H8NO3）]n （1）, has been prepared via the solvothermal method and characterized by IR, elemental analysis, UV- Vis diffuse-reflection spectra and single-crystal X-ray diffraction analysis. Complex 1 is a novel carboxylate-bridged one-dimensional helical cobalt（II） polymer, and the Co（II） centre exhibits an approximately square pyramidal CoClNO3 coordination geometry. It crystallizes in monoclinic, space group P21/n, with a = 9.1594（10）, b = 6.8864（7）, c = 17.290（2） , β = 102.629（3）o, C11H8ClCoNO3, Mr = 296.56, V = 1064.2（2） 3, Z = 4, Dc = 1.851 g/cm3, F（000） = 596, μ = 1.856 mm-1, the final R = 0.0308 and wR = 0.0807. Interestingly, the chain complexes are assembled to form two-dimensional networks through intermolecular face-to-face π-π stacking interactions with the centroid-to-centroid distance of 3.559（1） and the dihedral angle of 8.4（1）° between the aromatic rings.

A One-dimensional Cd(Ⅱ)Coordination Polymer Constructed from 1,4-Benzene-dicarboxylic Acid and 3-(2,6-Di(pyrazin-2-yl)pyridin-4-yl)-1H-indole:Synthesis,Structure and Photoluminescence

A new coordination polymer {[Cd（C_（21）H_（14）N_6）（C_8H_4O_4）]·H_2O}_n（1） was synthesized by an elaborate design via the reaction of 3-（2,6-di（pyrazin-2-yl）pyridin-4-yl）-1H-indole（bppi）,1,4-benzene-dicarboxylic acid（H2bdc） and cadmium（Ⅱ） nitrate in CH_3OH/H_2O mixed solvents. Complex 1 crystallizes in orthorhombic,space group Ccca with a = 20.012（4）,b = 31.881（6）,c = 19.808（4） ？,V = 12638（4） ？~3,Z = 16,C_（29）H_（20）CdN_6O_5,M_r = 644.91,D_c = 1.356 g·cm^（-3）,μ = 0.735 mm^（-1）,F（000） = 5184,GOOF = 1.046,the final R = 0.0405 and wR = 0.1063 for 6870 observed reflections（I 〉 2σ（I））. The Cd（Ⅱ） centre is hepta-coordinated by three N and four O atoms from one bppi terminal ligand and two bdc2– ligands,respectively,displaying a capped trigonal prism geometry. Structure extension gives coordination polymeric chains,in which the bdc2– linkers connect Cd（Ⅱ） cations into a one-dimensional（1D） coordination polymer along the c axis,giving zigzag chains with the Cd···Cd separation of 11.178（1） ？. The adjacent bppi terminal ligands in the chains are anti-periplanar conformation. The three-dimensional（3D） structure is stabilized by π···π stacking and hydrogen-bonding interactions to form a supramolecular self-penetrating network with 1D channels. In 1,there are voids 2999.7 ？~3 with 23.7% of per unit cell volume. Thermal analysis indicates that the framework of 1 is stable until 651 K and the photoluminescence of 1 in the solid shows very weak fluorescence at 382 and 560 nm upon excitation at 310 nm.

Preparation and Crystal Structure of 3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H- 1,2,4-triazolo[3,4-b][1,3,4 ]thiadiazine

3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4] thiadiazine, C 16H 11N 5O 3S, was prepared by the cyclization of 3-(2-hydroxyphenyl)-4-amino-5-mercapto-1,2,4-triazole with 2-bromo-4-nitroacetophenone. The compound was characterized by means of elemental analysis, IR, 1H NMR, 13C NMR, mass spectrometry, and X-ray diffraction. The compound crystallizes in a monoclinic system with space group C c, a=2.1853(4) nm, b=2.1192(5) nm, c=1.3526(3) nm, β=95.21(2)°, V=6.238(2) nm3 , D calcd.=1.505 Mg/m3, Z=16, F(000)=2916, R 1=0.0501, wR 2=0.0427. A comparison between the crystal structures of 1,2,4-triazolo[3,4-b] [1,3,4] thiadiazine and 1,2,4-triazolo[3,4-b][1,3,4] thiadiazole was made in the structural view. A two-dimensional network is formed by hydrogen bonds and π-π stacking interactions.

Crystal Structures and Photoluminescence of Two New Tetrazole-based Complexes

The solution reactions of the metal salts with 2,2＇-bipyfidine （2,2＇-bipy） and ethyl tetrazole-5-carboxylate （Hetzc） afforded two new tetrazole-based complexes M（2,2＇-bipy）2（etzc）2 （M=Mn 1, Zn 2）, and their crystal structures were determined by single-crystal X-ray diffraction analyses. Crystallographic data for 1： C28H26MnN12O4, Mr = 649.55, monoclinic, space group C2/c, a= 19.326（15）, b = 11.051（6）, c = 16.388（13）А,β= 117.38（4）° V= 3108（4） А^3, Z= 4, Dc = 1.388 g/cm^3, F（000） = 1340, R = 0.0557 and wR = 0.1269; and those for 2： C28H26ZnN12O4, Mr = 659.98, monoclinic, space group C2/c, a = 19.173（4）, b = 11.006（2）, c = 16.266（4） А, β= 118.11（3）°, V= 3027.4（11） А^3, Z = 4, Dc=1.448 g/cm3, F（000） = 1360, R = 0.0428 and wR = 0.1000. The structures of 1 and 2 are isomorphic and consist of isolated neutral mononuclear units. The metal atoms have highly distorted octahedral coordination environments with two N atoms from two etzc ligands and four N atoms from two 2,2＇-bipy molecules. The isolated mononuclear units are connected by π…π stacking interactions to generate one-dimensional chains. The thermal stability and photoluminescence have also been discussed.

Synthesis and Crystal Structure of (5-Hydroxy-6-methoxybenzofuran-3-yl)-(4-methoxyphenyl)methanone

Compound 1 （5-hydroxy-6-methoxybenzofuran-3-yl）（4-methoxyphenyl）metha- none, C17H1405, as a potential anti-breast cancer agent has been synthesized under microwave irradiation, which was further converted to （5,6-dihydroxybenzofuran-3-yl）（4-methoxyphenyi）me- thanone （2）. The compounds were characterized by MS and NMR spectra. Meanwhile, the crystal of 1 was obtained and determined by X-ray single-crystal diffraction. Crystal data： monoclinic system, space group P2/n, a = 8.908（6）, b = 10.505（7）, c = 15.452（11） A, β = 105.043（9）, V = 1396.4（16） A3, Z = 4, F（000） = 624, Dc = 1.419 g/cm3, p = 0.105 mm-1, R = 0.0513 and wR = 0.1246 for 14459 independent reflections （Rint = 0.0647） and 2488 observed ones （I〉 2σ（/））. lntermolecular O-H...O and π-π stacking interactions contributed to the stability of the structure.

Synthesis and Crystal Structure of N-Benzyl-N'-(2-pyridyl)urea and Its Mononuclear Cu(Ⅱ) Complex

A new ligand of N-benzyl-N＇-（2-pyridyl）urea L and its self-assembly product with CuCl2, [Cu（Ⅱ）LCl2]∞ 1, have been synthesized and structurally characterized by IR, 1H NMR and single-crystal X-ray diffraction analysis. In the structure of L, the urea groups adopt Z,E conformation to form dimers through intermolecular hydrogen bonds; while in complex 1, it assumes Z,Z conformation to fit for the coordination sphere of the Cu（Ⅱ） ions. The coordinated units are connected through intermolecular N-H...Cl hydrogen bonds to form an extended 2D framework. Finally, a 3D structure is obtained via π-π stacking interactions between pyridyl rings

1-D Open-channeled 3-D Supramolecular Frameworks Built with 2,3-Dihydroxybutanedioic Acid (H_4dhbd) and 2,2':6',2'-Terpyridine (tpy)~i

The complex [Cu2（H2dhbd）2（tpy）2]·CH3OH·4H2O 1 （H4dhbd =2,3-dihydroxybutanedioic acid, tpy = 2,2＇：6＇,2＇＇-terpyridine） has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal is of triclinic, space groups Pi with a= 8.6859（17）, b = 11.223（2）, c = 12.275（2）A, α = 112.454（3）, β= 98.435（3）, γ = 105.593（3）°, V= 1022.5（3） A^3, Z = 1, C38H42Cu2N6O18, Mr = 997.86, Dc = 1.621 g/cm^3, μ= 1.127 mm^-1, F（000） = 514, T = 293（2） K, the final R = 0.0539 and wR = 0.1394 for 3550 observed reflections with I 〉 2σ（I）. In the dinuclear unit, two Cun atoms are bridged by two H2dhbd chelate anions, forming a 14-membered ring, in which the distance of Cu…Cu atoms is 7.0526（12）A. Adjacent dinuclear units are constituted through π-π interactions and C-H…O hydrogen-bonding interactions, fashioning the final 3-D supramolecular framework with 1-D open channels. Variable-temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic exchange interactions between Cu^II ions.

From Dinuclear to Mononuclear:Co(Ⅱ) Complexes with Pyridine-2,6-Dicarboxylic Acid(H_2PDA)

Reactions of pyridine-2,6-dicarboxylic acid（H2PDA） with cobalt（Ⅱ） acetate resul-ted in two cobalt（Ⅱ） complexes,[Co（HPDA）2].2H2O.0.5CH3OH（1） and [Co2（PDA）2（H2O）5].2H2O（2）,which were characterized by single-crystal X-ray diffraction,IR and electronic absorption spectra.For both complexes,every cobalt atom lies in peudo-octahedral coordination geometry,and the whole structures present 3D frameworks linked by π-π stacking interactions and extensive hydrogen bonds.Magnetic studies showed λ =-83.38 cm-1 for（1） and g = 2.50 and J =-1.38 cm-1 for（2）.

Synthesis and Crystal Structure of Dichlorobis-(1-methylimidazoline-2(3H)-thione-S) Cobalt(II)

The reaction of anhydrous cobalt(II) dichloride with 1-methylimidazoline-2(3H)- thione in dichloromethane solution gave the title complex, [Co(C4H6N2S)2Cl2]. X-ray single-crystal analysis revealed that the complex crystallizes in a monoclinic system, space group P21/c, a = 13.9707(10), b = 10.0435(7), c = 10.3910(6) ?, β = 91.181(3)o, V = 1457.70(17) ?3, Z = 4, C8H12Cl2N4S2Co, Mr = 358.17, Dc = 1.632 g/cm3, μ = 1.813 mm–1, F(000) = 724, the final R = 0.0710 and wR = 0.1224 for 1549 observed reflections with I > 2σ(I). The Co atom is coordinated by two S atoms from two 1-methylimidazoline-2(3H)-thione ligands and two chloride ions in a slightly distorted tetrahedral geometry. The intramolecular classical hydrogen-bonding interactions involving chloride ions and N–H groups of the heterocyclic thione ligands are observed. The offset π-π stacking interactions between the imidazole rings of adjacent molecules with a face-to-face dis- tance of 3.604 ? are found in the packing diagram.

Synthesis and Crystal Structure of 4-(4,6-Dimethoxylpyrimidin-2-yl)-3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.

Synthesis and Adsorption Property of Two Polymeric Adsorbents with Pendent Ether Bonds

Two polymeric adsorbents, poly(methyl p-vinylbenzyl ether) and poly(phenyl p-vinylbenzyl ether), were synthesized from chloromethylated polystyrene. Their adsorption property for phenol in hexane solution was investigated. The results showed that the two adsorbents adsorb phenol from hexane solution through hydrogen-bonding and π-π stacking interaction.

Synthesis and Crystal Structure of a New Nickel(II) Complex with Unsymmetric Quadridentate Schiff Base Containing Oxime

The title complex, C18H15N3NiO3, has been prepared and characterized by X-ray diffraction analysis. It crystallizes in the monoclinic system, space group Cc with a = 10.939(2), b = 22.909(5), c = 6.907(1) ?, β = 116.75(3)°, V = 1545.7(5) ?, Z = 4, Mr = 380.04, F(000) = 784, Dc = 1.633 g/cm3 and μ(MoKα) = 1.279 mm–1. The structure was refined to R = 0.0472 and wR = 0.0893 for 2571 observed reflections with I > 2σ(I). The absolute structure Flack parameter X is 0.01(2). In this crystal structure, strong face-to-face π-π stacking interactions between adjacent molecules lead to a one-dimensional chain structure.

Selective Construction of Borromean Rings and Tweezer-Like Molecular Assembly Featuring Cp^(*)Rh/Ir Clips for Near-Infrared Photothermal Conversion

Making full use of coordination-driven self-assembly strategy,we herein described the selective synthesis of a molecular Borromean rings and two cases of “U”-shaped tweezer-like molecular assemblies in high yield by using bipyridyl ligands based on biphenyl unit and half-sandwich binuclear rhodium(III)/iridium(III) building blocks.The selective synthesis was realized by adjusting the length of dipyridyl arms.The utilization of curved U-shaped bipyridyl ligand L1 led to tweezer-like molecular assemblies.Subsequently,olefinic bonds were introduced to elongate dipyridyl arms obtaining ligand L2.The ligand L2 has two stable conformations,U-shape and Z-shape,which facilitated the formation of different topologies including the tetranuclear macrocycle and Borromean rings with different building blocks in this work.These structures in solid and solution all have been further confirmed by single-crystal X-ray diffraction,NMR analysis,and mass spectrometry.In addition,as an important driving force,π-π stacking interactions not only played a significant role in the stability of structures but also further triggered photothermal conversion in solution.The experimental results demonstrated that compounds 1a and 2 had good NIR photothermal conversion efficiency (11.83% and 17.76%),and further analysis found the photothermal conversion efficiency had a gradual increase in the trend with the π-π stacking interactions increasing.This research expands the application of topological structures in materials science and provides a new idea for the synthesis of novel photothermal conversion materials.

新型Cu(II)-邻菲咯啉-丁二酸三元配合物:[Cu(phen)_2L](H_2L)·5H_2O(1)和[(phen)_2CuLCu(phen)_2]L·10H_2O(2)的合成及晶体结构(H_2L=丁二酸(C_4H_6O_4))

合成了两种新型Cu(II) 邻菲咯啉 丁二酸三元配合物,即[Cu(phen)2L](H2L)·5H2O(1)和[(phen)2CuLCu(phen)2]L·10H2O(2),它们均属三斜晶系,空间群为P1(no.2),晶胞参数分别为:(1)a=10.282(3),b=12.141(3),c=14.233(4) ,α=78.55(2)°,β=76.50(2)°,γ=84.29(2)°,V=1690.7(9) 3,Z=2,R=0.1021,wR2=0.1387;(2)a=12.943(2),b=14.436(2),c=17.974(3) ,α=75.128(9)°,β=69.030(9)°,γ=69.02(1)°,V=2896.2(9) 3,Z=2,R=0.0976,wR2=0.2240.结构分析表明,每个Cu原子与分属于2个邻菲咯啉配体的4个N原子和来自丁二酸根的2个O原子形成配位数为6的畸变八面体CuN4O2.配合物(1)中配位分子间通过芳环堆积作用形成平行[011]方向的一维超分子链,超分子链之间通过结晶水分子的氢键作用形成二维层,并进而堆积形成一维隧道和三维骨架,丁二酸分子和其余结晶水分子位于隧道内.配合物(2)中丁二酸根桥联的双核配阳离子借助芳环堆积作用形成平行于(010)面的正电性二维层,C4H4O42-离子和结晶水分子位于正电层之间并形成负电性二维网络层.