Synthesis and properties of novel polyimides derived from 2,2′,3,3′‐benzophenonetetracarboxylic dianhydride

A new synthetic route to 2,2′,3,3′‐BTDA (where BTDA is benzophenonetetracarboxylic dianhydride), an isomer of 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA, is described. Single‐crystal X‐ray diffraction analysis of 2,2′,3,3′‐BTDA has shown that this dianhydride has a bent and noncoplanar structure. The polymerizations of 2,2′,3,3′‐BTDA with 4,4′‐oxydianiline (ODA) and 4,4′‐bis(4‐aminophenoxy)benzene (TPEQ) have been investigated with a conventional two‐step process. A trend of cyclic oligomers forming in the reaction of 2,2′,3,3′‐BTDA and ODA has been found and characterized with IR, NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and elemental analyses. Films based on 2,2′,3,3′‐BTDA/TPEQ can only be obtained from corresponding polyimide (PI) solutions prepared by chemical imidization because those from their polyamic acids by thermal imidization are brittle. PIs from 2,2′,3,3′‐BTDA have lower inherent viscosities and worse thermal and mechanical properties than the corresponding 2,3′,3′,4′‐BTDA‐ and 3,3′,4,4′‐BTDA‐based PIs. PIs from 2,2′,3,3′‐BTDA and 2,3′,3′,4′‐BTDA are amorphous, whereas those from 3,3′,4,4′‐BTDA have some crystallinity, according to wide‐angle X‐ray diffraction. Furthermore, PIs from 2,2′,3,3′‐BTDA have better solubility, higher glass‐transition temperatures, and higher melt viscosity than those from 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA. Model compounds have been prepared to explain the order of the glass‐transition temperatures found in the isomeric PI series. The isomer effects on the PI properties are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2130–2144, 2004     

A Novel Coordination Polymer, [Ag4^1 （bpdc）（H2bpdc）（Hbpdc）2]n （bpdc = 2,2＇-bipyridyl-3,3＇-dicarboxylate）： Coordination Models of bpdc Ligands

A novel coordination polymer, [Ag₄ppdc)(H₂bpdc)(Hbpdc)₂] (bpdc = 2,2′‐bipyridyl‐3,3′‐dicarboxylate), was hydrothermally synthesized at 403 K and structurally characterized by single crystal X‐ray diffraction analysis. The compound crystalizes in the monoclinic space group C2/c with a=1.9516(4) nm, b=1.9503(4) nm. c=1.2566(3) nm, and β=112.48(3)°. In the two‐dimensional crystal structure, Ag^I center is coordinated, in a scarce coordination environment, double‐capped tetrahedron, by one bpdc ligand to form N‐Ag‐N chelate bond via two pyridyl N atoms, and other two bpdc ligands to form two O‐Ag‐O chelate bonds, respectively, via two carboxyl O atoms. The bpdc ligands are present in one non‐protonated form, bpdc, and two protonated forms, Hbpdc and H2bpdc, which all act as μ3‐ligand in a hexadentate fashion (N, N′; O, O′; O, O′) to coordinate with three Ag centers, respectively, through the three chelate bonds. This coordinated fashion of bpdc ligand is first found in the title compound. W‐Us‐NIR reflectance spectroscopy study revealed insulator nature for the crystal with an optical energy gap of 3.1 eV.     

Density functional theory study on surface-enhanced Raman scattering of 4,4′-azopyridine on silver

Surface-enhanced Raman scattering (SERS) of 4,4′-azopyridine (AZPY) on silver foil substrate was measured under 1064 nm excitation lines. Density-functional theory (DFT) methods were used to calculate the structure and vibrational spectra of models such as Ag–AZPY, Ag₄–AZPY and Ag₆–AZPY complexes with B3LYP/6-31++G(d,p)(C,H,N)/Lanl2dz(Ag) basis set. The Raman bands of AZPY were identified on the ground of analog computation of potential energy distribution. The calculated spectra of Ag₄–AZPY and Ag₆–AZPY models were much approximated to the experimental results than that of Ag–AZPY model. The DFT results showed that the angles between two pyridyl rings keep 0° from AZPY to Ag–AZPY, Ag₄–AZPY and Ag₆–AZPY model. The energy gaps between the HOMO and LUMO changed from 363 to 1140 nm for AZPY-Ag complexes according to the DFT results. An conclusion was conceived that chemical enhancement mechanism may play an important role in the SERS of AZPY on silver substrate.     

Masking of Lewis acidity trends in the solid‐state structures of trichlorido‐ and tribromido(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)gallium(III)

The molecular structures of trichlorido(2,2′:6′,2′′‐terpyridine‐κ³N,N′,N′′)gallium(III), [GaCl₃(C₁₅H₁₁N₃)], and tribromido(2,2′:6′,2′′‐terpyridine‐κ³N,N′,N′′)gallium(III), [GaBr₃(C₁₅H₁₁N₃)], are isostructural, with the Ga^III atom displaying an octahedral geometry. It is shown that the Ga—N distances in the two complexes are the same within experimental error, in contrast to expected bond lengthening in the bromide complex due to the lower Lewis acidity of GaBr₃. Thus, masking of the Lewis acidity trends in the solid state is observed not only for complexes of group 13 metal halides with monodentate ligands but for complexes with the polydentate 2,2′:6′,2′′‐terpyridine donor as well.     

New organo‐soluble aromatic polyimides based on 3,3′,5,5′‐tetrabromo‐2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride and aromatic diamines

New aromatic tetracarboxylic dianhydride, having isopropylidene and bromo‐substituted arylene ether structure 3,3′,5,5′‐tetrabromo‐2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride, was synthesized by the reaction of 4‐nitrophthalonitrile with 3,3′,5,5′‐tetrabromobisphenol A, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). The novel aromatic polyetherimides having inherent viscosities up to 1.04 dL g⁻¹ were obtained by either a one‐step or a conventional two‐step polymerization process starting from the bis(ether anhydride) and various aromatic diamines. All the polyimides showed typical amorphous diffraction patterns. Most of the polyimides were readily soluble in common organic solvents such as N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), pyridine, and even in less polar solvents like chloroform and tetrahydrofuran (THF). These aromatic polyimides had glass transition temperatures in the range of 256–303°C, depending on the nature of the diamine moiety. Thermogravimetric analysis (TGA) showed that all polymers were stable, with 10% weight loss recorded above 470°C in nitrogen. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1673–1680, 1999     

One‐dimensional CuII coordination polymers containing C2h‐symmetric 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate linkers

Two new one‐dimensional Cu^II coordination polymers (CPs) containing the C_2h‐symmetric terphenyl‐based dicarboxylate linker 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate (3,3′‐TPDC), namely catena‐poly[[bis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ⁴O,O′:O′′:O′′′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂]·H₂O}_n, (I), and catena‐poly[[aquabis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ²O³:O^3′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂(H₂O)]·H₂O}_n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours, i.e. violet plates for (I) and blue needles for (II), both of which were analysed by X‐ray crystallography. The 3,3′‐TPDC bridging ligands coordinate the Cu^II ions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one‐dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutually trans positions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one‐dimensional coordination polymer chains, forming a two‐dimensional network in (I) and a three‐dimensional network in (II).     

Structural and theoretical characterization of a new twisted 4′‐substituted terpyridine compound: 4′‐(isoquinolin‐4‐yl)‐2,2′:6′,2′′‐terpyridine

4′‐Substituted derivatives of 2,2′:6′,2′′‐terpyridine with N‐containing heteroaromatic substituents, such as pyridyl groups, might be able to coordinate metal centres through the extra N‐donor atom, in addition to the chelating terpyridine N atoms. The incorporation of these peripheral N‐donor sites would also allow for the diversification of the types of noncovalent interactions present, such as hydrogen bonding and π–π stacking. The title compound, C₂₄H₁₆N₄, consists of a 2,2′:6′,2′′‐terpyridine nucleus (tpy), with a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus deviates slightly from planarity, with interplanar angles between the lateral and central py rings in the range 2.24 (7)–7.90 (7)°, while the isq group is rotated significantly [by 46.57 (6)°] out of this planar scheme, associated with a short H_tpy…H_isq contact of 2.32 Å. There are no strong noncovalent interactions in the structure, the main ones being of the π–π and C—H…π types, giving rise to columnar arrays along [001], further linked by C—H…N hydrogen bonds into a three‐dimensional supramolecular structure. An Atoms In Molecules (AIM) analysis of the noncovalent interactions provided illuminating results, and while confirming the bonding character for all those interactions unquestionable from a geometrical point of view, it also provided answers for some cases where geometric parameters are not informative, in particular, the short H_tpy…H_isq contact of 2.32 Å to which AIM ascribed an attractive character.     

Conformations and rotational barriers of 2,2′‐bithiazole and 4,4′‐dimethyl‐2,2′‐bithiazole semiemperical,ab initio,and density functional theory calculations

Conformational properties of 2,2′‐bithiazole and 4,4′‐dimethyl‐2,2′‐ bithiazole have been studied by using AM1 and PM3 semiemperical methods and ab initio HF/6‐311+G* and B3LYP/6‐311+G* calculations. All methods agree that the planar s‐trans conformation is the global minimum and the perpendicular conformation is the transition state. Additional local minima were found using the Hartree–Fock (HF) and B3LYP levels for 2,2′‐bithiazole while for 4,4′‐dimethyl derivative the minima was located only at the MP2//B3LYP level. The barrier heights for rotation are 1.72, 7.69, and 7.88 kcal/mol at the PM3, HF, and B3LYP levels, respectively, and methyl substitution did not affect appreciably this value. Fourier expansion terms and bond orders were used to explain the origins of the rotational barrier in terms of π conjugation, electrostatic interaction, and steric effects, which represent the main factors in the shape of the rotational barrier. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 367–377, 2000     

Syntheses,Structures and Characterization of Four Metal‐Organic Frameworks constructed by 2,2′,6,6′‐Tetramethoxy‐4,4′‐biphenyldicarboxylic Acid

Four metal‐organic frameworks (MOFs), {[Mn_3.5L(OH)(HCOO)₄(DMF)] · H₂O} ( 1 ), {[In_2.5L₂O(OH)_1.5(H₂O)₂] · DMF · CH₃CN · 2H₂O} ( 2 ), {[Pb₄L₃O(DMA)] · CH₃CN} ( 3 ), and {[LaL(NO₃)(DMF)₂] · 2H₂O} ( 4 ) were synthesized by utilizing the ligand 2,2′,6,6′‐tetramethoxy‐4,4′‐biphenyldicarboxylic acid (H₂L) via solvothermal methods. All MOFs were characterized by single‐crystal X‐ray diffraction, powder X‐ray diffraction, thermogravimetric analysis, and infrared spectroscopy. In 1 , the Mn²⁺ ions are interconnected by formic groups in situ produced via DMF decomposition to form a rare 2D macrocyclic plane, which is further linked by L^2– to construct the final 3D network. In 2 , 1D zip‐like infinite chain is formed and then interconnected to build the 3D framework. In 3 , a [Pb₆(μ₄‐O)₂(O₂C)₁₀(DMA)₂] cluster with a centrosymmetric [Pb₆(μ₄‐O)₂]⁸⁺ octahedral core is formed in the 3D structure. In 4 , the La³⁺ ions are connected with each other through carboxylate groups of L^2– to generate 1D zigzag chain, which is further linked by L^2– to construct a 3D network with sra topology. Solid photoluminescence properties of 3 and 4 were also investigated.     

Four (2,2′‐bipyridyl)(ferrocenyl)boronium derivatives

Crystal structures are reported for four (2,2′‐bipyridyl)(ferrocenyl)boronium derivatives, namely (2,2′‐bipyridyl)(ethenyl)(ferrocenyl)boronium hexafluoridophosphate, [Fe(C₅H₅)(C₁₇H₁₅BN₂)]PF₆, (Ib), (2,2′‐bipyridyl)(tert‐butylamino)(ferrocenyl)boronium bromide, [Fe(C₅H₅)(C₁₉H₂₂BN₃)]Br, (IIa), (2,2′‐bipyridyl)(ferrocenyl)(4‐methoxyphenylamino)boronium hexafluoridophosphate acetonitrile hemisolvate, [Fe(C₅H₅)(C₂₂H₂₀BN₃O)]PF₆·0.5CH₃CN, (IIIb), and 1,1′‐bis[(2,2′‐bipyridyl)(cyanomethyl)boronium]ferrocene bis(hexafluoridophosphate), [Fe(C₁₇H₁₄BN₃)₂](PF₆)₂, (IVb). The asymmetric unit of (IIIb) contains two independent cations with very similar conformations. The B atom has a distorted tetrahedral coordination in all four structures. The cyclopentadienyl rings of (Ib), (IIa) and (IIIb) are approximately eclipsed, while a bisecting conformation is found for (IVb). The N—H groups of (IIa) and (IIIb) are shielded by the ferrocenyl and tert‐butyl or phenyl groups and are therefore not involved in hydrogen bonding. The B—N(amine) bond lengths are shortened by delocalization of π‐electrons. In the cations with an amine substituent at boron, the B—N(bipyridyl) bonds are 0.035 (3) Å longer than in the cations with a methylene C atom bonded to boron. A similar lengthening of the B—N(bipyridyl) bonds is found in a survey of related cations with an oxy group attached to the B atom.     

3,3′‐Diamino‐N‐methyldipropylamine as a versatile affinity ligand

Currently, in biomedicine and biotechnology fields, there is a growing need to develop and produce biomolecules with a high degree of purity. To accomplish this goal, new purification methods are being developed looking for higher performance, efficiency, selectivity, and cost‐effectiveness. Affinity chromatography is considered one of the most highly selective methods for biomolecules purification. The purpose of this work is to explore a new type of a structurally simple ligand immobilized onto an agarose matrix to be used in affinity chromatography. The ligand in this study, 3,3′‐diamino‐N‐methyldipropylamine has shown low toxicity and low cost of preparation. Moreover, the ability of the ligand to be used in affinity chromatography to purify proteins and nucleic acids was verified. An increasing sodium chloride gradient, using salt concentrations up to 500 mM, was suitable to accomplish the purification of these biomolecules, meaning that the new support allows the recovery of target biomolecules under mild conditions. Thus, the 3,3′‐diamino‐N‐methyldipropylamine ligand is shown to be a useful and versatile tool in chromatographic experiments, with very good results either for proteins or supercoiled plasmid isoform purification.     

Synthesis and characterization of new soluble polyamides derived from 3,3′,5,5′-tetramethyl-2,2-bis[4-(4-carboxyphenoxy)phenyl]propane

A series of new soluble polyamides having isopropylidene and methyl-substituted arylene ether moieties in the polymer chain were prepared by the direct polycondensation of 3,3′,5,5′-tetramethyl-2,2-bis[4-(4-carboxyphenoxy)phenyl]propane and various diamines in N-methyl-2-pyrrolidinone (NMP) containing CaCl₂ using triphenyl phosphite and pyridine as condensing agents. Polymers were produced with moderate to high inherent viscosities of 0.85–1.47 dL g⁻¹ while the weight-average molecular weight and number-average molecular weight were in the range of 86,700–259,000 and 43,300–119,000, respectively. All the polymers were readily dissolved in polar aprotic solvents such as NMP, N,N-dimethylacetamide, and N,N-dimethylformamide, as well as less polar solvents such as m-cresol and pyridine, and even soluble in tetrahydrofuran. These polymers were solution-cast into transparent, flexible and tough films. All of the polymers were amorphous and the polyamide films had a tensile strength range of 82–122 MPa, an elongation at break range of 6–18%, and a tensile modulus range of 2.0–2.8 GPa. These polyamides had glass transition temperatures between 233–260°C and 10% weight loss temperatures in the range of 450–489 and 459–493°C in nitrogen and air atmosphere, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1997–2003, 1999     

Synthesis and characterization of thermally stable sulfonated polybenzimidazoles obtained from 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone

A novel sulfonated aromatic diacid, 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone (DSDCDPS), was successfully synthesized from 4,4′‐dimethyldiphenylsulfone by sulfonation and further oxidation. A series of sulfonated polybenzimidazoles (sPBI‐SS) with various sulfonation degrees was prepared from DSDCDPS, 4,4′‐sulfonyldibenzoic acid and 3,3′‐diaminobenzidine by solution copolycondensation in poly(phosphoric acid). The chemical structure of the resulting sPBI‐SS was confirmed by FTIR and ¹H NMR. The DSDCDPS‐based sPBI‐SS with the number‐average molecular weights of 32,000–55,000 were easy to dissolve in polar aprotic solvents such as DMF, DMSO, and DMAc, and could be cast into transparent, tough, and flexible membranes. The membranes presented good thermal stabilities (5% weight loss temperatures higher than 430 °C), and the thermal degradation activation energies of the sulfonic group of sPBI‐SS40 evaluated under N₂ by both Ozawa and Kissinger methods were 266.06 and 264.79 kJ/mol, respectively. The membranes also exhibited high storage moduli, glass transition temperatures (above 238 °C) and tensile strengths (～80 MPa), in addition to water uptakes (22.3–25.2%) and low swelling degrees (<14.0%). © 2005 Wiley Periodicals, Inc. J Polym Sci A: Polym Chem 43: 4363–4372, 2005     

Building Functionality into 4′‐Hydrazone Derivatives of 2,2′: 6′,2″‐Terpyridine

The syntheses of the five 2,2′: 6′,2″‐terpyridine (tpy) ligands 5 – 9 functionalized in the 4′‐position with a hydrazone substituent RR′C?N? NH (R=R′=Me; R=H, R′=4‐BrC₆H₄, 4‐O₂NC₆H₄, 4‐MeOC₆H₄, or 3,5‐(MeO)₂C₆H₃) are described. Protonation of the tpy domain of the ligands is facile. Solution behaviour has been studied by NMR and electronic spectroscopies. Representative structural data are presented for neutral and monoprotonated ligands, and illustrate that H‐bonding involving the formal amine NH unit is a dominant structural motif in all cases.     

Synthesis,Crystal Structures and Fluorescent Properties of Two 2,2′‐Biquinoline‐4,4′‐dicarboxylate‐based Cadmium(II) and Cobalt(II) Complexes

Two metal‐organic coordination polymers with one‐dimensional infinite chain motif, [Cd(bqdc)(phen)₂]_n ( 1 ) and [Co(bqdc)(phen)(H₂O)₂]_n ( 2 ) (H₂bqdc = 2,2′‐biquinoline‐4,4′‐dicarboxylic acid, phen = 1,10‐phenanthroline), have been synthesized under similar solv/hydrothermal conditions and fully structural characterized by elemental analysis, IR, and single‐crystal X‐ray crystallography. Their thermal stability and photoluminescence properties were further investigated by TG‐DTA and fluorescence spectra. In both complexes, the adjacent metal ions (Cd^II for 1 and Co^II for 2 ) are linked together by dicarboxylate groups of bqdc dianions in chelating bidentate and monodentate modes, respectively, generating a zigzag chain for 1 and linear chain for 2 . The relatively higher thermal stability up to 324 °C for 1 and strong fluorescence emissions jointly suggest that they are good candidates for luminescent materials.     

Interaction of dimethyltin(IV) dichloride with 5′‐IMP and 5′‐UMP

The formation constants of the species formed in the systems H⁺ + dimethyltin(IV) + 5′‐IMP and 5′‐UMP, H⁺ + 5′‐IMP and H⁺ + 5′‐UMP have been determined in aqueous solution in the pH range 1.5–9.5 at constant temperature (25 °C) and constant ionic strength (0.1 mol dm⁻³ NaClO₄), using spectrophotometric and potentiometric techniques. ¹H and ³¹P NMR investigations in aqueous solution confirmed the species formation. The precipitated complexes of IMP and UMP by Me₂Sn(IV)²⁺ at low pH values were characterized by elemental analysis and FTIR spectroscopy methods, the bonding sites of the ligands were determined and ruled out purine and pyrimidine moieties (N‐7 and N‐1 in IMP and N‐3 in UMP, respectively) while a bidentated coordination of the phosphate group is concluded in both cases. Finally, the experiments revealed the existence of complexes with trigonal bipyramidal structures that is in agreement with similar systems resulted previously. Copyright © 2008 John Wiley & Sons, Ltd.     

Quality control of PET radiopharmaceuticals by high‐performance liquid chromatography with tris(2,2′‐bipyridyl)ruthenium(II) electrogenerated chemiluminescence detection

A highly sensitive reversed‐phase liquid chromatographic (HPLC) method was investigated to analyze a range of positron emission tomography (PET) radiopharmaceuticals using electrogenerated chemiluminescence (ECL) detection. ECL is based on the reaction of PET molecules with tris(2,2′‐bipyridyl)ruthenium(III) [Ru(bpy)₃³⁺], which is generated through the on‐line electro‐oxidation of Ru(bpy)₃²⁺. In 21 different radiopharmaceuticals studied, 18 compounds could be detected with detection limits (signal‐to‐noise ratio = 3) of 0.12–72 ng/mL per 20 μL injection. Sufficient reproducibility and linearity were obtained for the quantitative determination of PET molecules in pharmaceutical fluid. This method could be successfully applied to quality control tests of PET radiopharmaceuticals with ultra‐high specific radioactivity. Copyright © 2009 John Wiley & Sons, Ltd.     

pH‐Dependent conjugate addition of arylboronic acids to α,β‐unsaturated enones catalyzed by a reusable palladium(II)/cationic 2,2′‐bipyridyl system in water under air

A reusable Pd(NH₃)₂Cl₂/cationic 2,2′‐bipyridyl system for the catalysis of the conjugate addition of arylboronic acids to α,β‐unsaturated enones in water under air was developed. Addition of arylboronic acids to both cyclic and acyclic enones progressed smoothly, providing the products in good to high yields, the best result being obtained when HBF₄ was used to adjust the pH value to 1.0. After the reaction, the residual aqueous solution could be reused several times, making the reaction greener and reducing wastage of precious metals. Copyright © 2010 John Wiley & Sons, Ltd.     

Two complexes of PtIV and AuIII with 2,2′‐dipyridylamine and 2,2′‐dipyridylaminide ligands

Two noble metal complexes involving ancillary chloride ligands and chelating 2,2′‐bipyridylamine (Hdpa) or its deprotonated derivative (dpa), namely [bis(pyridin‐2‐yl‐κN)amine]tetrachloridoplatinum(IV), [PtCl₄(C₁₀H₉N₃)], and [bis(pyridin‐2‐yl‐κN)aminido]dichloridogold(III), [AuCl₂(C₁₀H₈N₃)], are presented and structurally characterized. The metal atom in the former has a slightly distorted octahedral coordination environment, formed by four chloride ligands and two pyridyl N atoms of Hdpa, while the metal atom in the latter has a slightly distorted square‐planar coordination environment, formed by two chloride ligands and two pyridyl N atoms of dpa. The difference in conjugation between the pyridine rings in normal and deprotonated 2,2′‐dipyridylamine is discussed on the basis of the structural features of these complexes. The influence of weak interactions on the supramolecular structures of the complexes, providing one‐dimensional chains of [PtCl₄(C₁₀H₉N₃)] and dimers of [AuCl₂(C₁₀H₈N₃)], are discussed.     

Effect of Metal Ions on the Structures of Coordination Polymers Based on Biphenyl‐2,2′,4,4′‐Tetracarboxylate

Two new coordination polymers, {[Cd₂(btc)(2,2′‐bpy)₂] · H₂O}_n ( 1 ) and [Zn₂(btc)(2,2′‐bpy)(H₂O)]_n ( 2 ) (H₄btc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid, 2,2′‐bpy = 2,2′‐bipyridine), were synthesized hydrothermally under similar conditions and characterized by elemental analysis, IR spectra, TGA, and single‐crystal X‐ray diffraction analysis. In complexes 1 and 2 , the (btc)^4– ligand acts as connectors to link metal ions to give a 2D bilayer network of 1 and a 3D metal‐organic framework of 2 , respectively. The differences in the structures are induced by diverging coordination modes of the (btc)^4– ligand, which can be attributed to the difference metal ions in sizes. The results indicate that metal ions have significant effects on the formation and structures of the final complexes. Additionally, the fluorescent properties of the two complexes were also studied in the solid state at room temperature.