Cyclic and multicyclic poly(ether sulfone)s by polycondensation of 5,5′,6,6′‐tetrahydroxy‐ 3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐difluorodiphenylsulfone

5.5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐difluorodiphenylsulfone (DFDPS) in DMSO with K₂CO₃ as catalyst and azeotopic removal of water. The feed ratio of DFDPS/TTSBI was varied from 1.0/1.0 to 2.0/1.0 at concentrations avoiding gelation. At feed ratios around 1.0/1.0 hyperbranched polymers were a minority and cyclic poly(ether sulfone)s were the predominant reaction products. With increasing feed ratio of DFDPS more and more multicyclic polymers were formed, and at a feed ratio of 1.9/1.0 perfect multicycles free of functional groups were the vast majority of the reaction product. Despite variation of the reaction conditions quantitative conversion was not achieved. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5597–5605, 2007     

Syntheses of multicyclic poly(ether sulfone)s from 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐bis(4‐chlorophenyl) sulfones

5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐dichlorodiphenyl sulfone (DCDPS) or with 4,4′‐bis(4‐chlorophenyl sulfonyl) biphenyl (BCSBP) in DMSO. Concentration and feed ratio were optimized to avoid gelation and to obtain a maximum yield of multicyclic polyethers free of functional groups. Regardless of these reaction conditions, only low fractions of perfect multicycles were obtained from DCDPS apparently due to steric hindrance of ring closure. Under the same conditions high fractions of perfect multicycles were achieved with the longer and more flexible DCSBP. The reaction products were characterized by MALDI‐TOF mass spectrometry, ¹H‐NMR spectroscopy viscosity, and DSC measurements. Relatively low glass transition temperatures (T_gs ≈ 160–175 °C) were found. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3732–3739, 2008     

Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169     

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     

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.     

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).     

Possible structural effect of a′,b′‐dihydroxyacetophenone units in the preformed oligoesters upon copolycondensation with isomeric c′,d′‐dihydroxyacetophenones by TsCl/dimethylformamide/pyridine

A two‐stage copolycondensation of a mixture of equal parts of isophthalic acid and terephthalic acid first with a′,b′‐dihydroxyacetophenone (a′,b′‐DHAP) and then with isomeric c′,d′‐DHAP was examined at 60 and 80 °C. A structurally selective reaction was observed. At 80 °C, the preformed oligomers from symmetrically substituted 2′,6′‐DHAP reacted better with similarly substituted 2′,6′‐ or 3′,5′‐DHAP to give the copolymers of significantly higher inherent viscosity values than from the reaction with asymmetrically substituted 2′,4′‐DHAP, whereas at 60 °C they did almost equally well with any c′,d′‐DHAP. Similarly, the reaction of oligomers from 2′,4′‐DHAP with asymmetrically substituted 2′,4′‐DHAP or 2,4‐dihydroxybenzophenone yielded better results than those from the reaction with 2′,6′‐ or 3′,5′‐DHAP at both temperatures. The copolycondensations with comonomers of the structure independent of DHAPs were not affected by the preformed oligomers from DHAPs. The results are discussed in terms of the distributions of resulting oligomers determined by gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 616–623, 2003     

Linear High Molecular Weight Ladder Polymer via Fast Polycondensation of 5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane with 1,4‐Dicyanotetrafluorobenzene

A high molecular weight ladder polymer based on 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane and 1,4‐dicyanotetraflurobenzene has been synthesized by polycondensation under high‐intensity mixing conditions at about 155 °C and cyclic‐free products were obtained in high yield with low molecular weight distribution (1.7–2.3). The reaction could be completed within a few minutes. The polymer properties were characterized by GPC, ¹H NMR, ¹³C NMR, F NMR, FT‐IR, and MALDI‐TOF MS. In addition, the mechanical properties, apparent surface areas and gas permeability are also reported. This procedure can also be used for the synthesis of other ladder polymers by irreversible polycondensations of tetraphenols with activated tetrafluoro aromatics.

     

A Novel,One‐Pot Four‐Component Route to 2′‐Thioxo‐2′,3′‐dihydrospiro[indole‐3,6′‐[1,3]thiazin]‐2‐one Derivatives

An efficient route to 2′,3′‐dihydro‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives is described. It involves the reaction of isatine, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one, and different amines in the presence of CS₂ in dry MeOH at reflux (Scheme 1). The alkyl carbamodithioate, which results from the addition of the amine to CS₂, is added to the α,β‐unsaturated ketone, resulting from the reaction between 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one and isatine, to produce the 3′‐alkyl‐2′,3′‐dihydro‐4′‐phenyl‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives in excellent yields (Scheme 2). Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses.     

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     

Multicyclic polyethers with pendant keto groups by polycondensation of silylated 1,1,1‐tris(4‐hydroxyphenyl)ethane

1,1,1‐Tris(4‐trimethylsiloxyphenyl)ethane, (silylated THPE), was polycondensed with 2,4‐difluoroacetophenone and 2,4‐difluorobenzophenone. All polycondensations were performed in N‐methylpyrrolidone with K₂CO₃ as promotor. The feed ratio THPE/difluoroaromat was varied from 1.0:1.3 to 1.0:1.5. Instead of hyperbranched polymers or gels, soluble multicyclic oligo‐ and polyethers were identified as main reaction products by MALDI‐TOF mass spectrometry in all experiments. At feed ratios around 1.0:1.5 multicycles free of functional group were the main products. However, when isomeric a₂‐monomers such as 2,6‐difluoroacetophenone, 2,6‐difluorobenzophenone (or 2,6‐difluorodiphenylsulfone) were used, gelation occurred at feed ratios as low as 1.0:1.1. An explanation of the different cyclization tendencies on the basis of different conformations is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6233–6246, 2005     

Two Bulky Conjugated 4′‐(4‐Hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine‐based Layered Complexes: Synthesis,Structure, and Photocatalytic Hydrogen Evolution Activity

Two new layered complexes with the formulas of {[Cu(H₂O)(HL)₂Cl](NO₃)}_n ( 1 ) and {[Cu(H₂O)₂(HL)₂](NO₃)₂}_n ( 2 ) were solvothermally synthesized by the reactions of the bulky conjugated 4′‐(4‐hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine ligand (HL) with different Cu^II salts, which were further used as photocatalysts to achieve hydrogen production from water splitting. Single‐crystal structural analyses reveal that both complexes feature coplanar (4 4) layers with different connection manners between the HL extended Z‐shaped chains. More interestingly, 1 possessing more negative conduction band potential and higher structural stability exhibits a large hydrogen production rate of 2.43 mmol · g^–1 · h^–1, which is four times higher than that of 2 . Thus, the Cu^II‐based coordination polymers modified by the bulky conjugated organic ligand can become potentially promising non‐Pt photocatalysts for hydrogen production from water splitting.     

Nucleosides 4: Synthesis of 2′,3′-Didehydro-2′,3′-dideoxydoridosine and 2′,3′-Dideoxydoridosine as Potential Antihypertensive Agents

To measure the hydrophobic character of the ribose moiety of doridosine on the adenosine receptors, 2′,3′-didehydro-2′,3′-dideoxydoridosine (2) and 2′,3′-dideoxydoridosine (3) were prepared. Initial treatment of doridosine with N,N-dimethylformamide diethylacetal, and subsequently with tert-butyldimethylsilyl chloride gave 5. Compound 5 was then reacted with 1,1′-thiocarbonyldiimidazole and the resulting thionocarbonate 6 was heated with triethyl phosphite at 135°C to afford 7. Treatment of compound 7 with tetrabutylammonium fluoride and methanolic ammonia furnished compound 2 in good yield. Compound 2 was subjected to catalytic hydrogenation affording compound 3 in 85% yield.     

Preparation and physical properties of poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) films

To prepare thermally stable and high‐performance polymeric films, new solvent‐soluble aromatic polyamides with a carbamoyl pendant group, namely poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) (p‐PDCBTA) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) (m‐PDCBTA), were synthesized. The polymers were cyclized at around 200 to 350 °C to form quinazolone and benzoxazinone units along the polymer backbone. The decomposition onset temperatures of the cyclized m‐ and p‐PDCBTAs were 457 and 524 °C, respectively, lower than that of poly(p‐phenylene terephthalamide) (566 °C). For the p‐PDCBTA film drawn by 40% and heat‐treated, the tensile strength and Young's modulus were 421 MPa and 16.4 GPa, respectively. The film cyclized at 350 °C showed a storage modulus (E′) of 1 × 10¹¹ dyne/cm² (10 GPa) over the temperature range of room temperature to 400 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 775–780, 2000     

An Efficient Synthesis of 1′,7′,8′,9′‐Tetrahydrospiro[indoline‐3,4′‐pyrazolo[3,4‐b]quinoline]‐2,5′(6′H)‐dione Derivatives in Aqueous Medium

An efficient and green reactions of isatins, 3‐amine‐1H‐pyrazole (5‐methyl‐1H‐pyrazol‐3‐amine) and 1,3‐diketone in aqueous medium for the synthesis of novel 1′,7′,8′,9′‐tetrahydrospiro[indoline‐3,4′‐pyrazolo[3,4‐b]quinoline]‐2,5′(6′H)‐dione derivatives were reported in this research. The advantages of this reaction are simple operation, mild‐reaction conditions, wide scope substrate, high yields, and friendly environment. The products were confirmed by IR, ¹H NMR, ¹³C NMR, and HRMS.     

A zinc(II) metal–organic framework with a novel topology formed from 4,4′,4′′‐nitrilotribenzoate and 4,4′‐bipyridine ligands

A metal–organic framework with a novel topology, poly[sesqui(μ₂‐4,4′‐bipyridine)bis(dimethylformamide)bis(μ₄‐4,4′,4′′‐nitrilotribenzoato)trizinc(II)], [Zn₃(C₂₁H₁₂NO₆)₂(C₁₀H₈N₂)_1.5(C₃H₇NO)₂]_n, was obtained by the solvothermal method using 4,4′,4′′‐nitrilotribenzoic acid and 4,4′‐bipyridine (bipy). The structure, determined by single‐crystal X‐ray diffraction analysis, possesses three kinds of crystallographically independent Zn^II cations, as well as binuclear Zn₂(COO)₄(bipy)₂ paddle‐wheel clusters, and can be reduced to a novel topology of a (3,3,6)‐connected 3‐nodal net, with the Schläfli symbol {5.6²}₄{5².6}₄{5⁸.8⁷} according to the topological analysis.     

Synthesis of novel hyperbranched poly(ester‐amide)s based on neutral α‐amino acids via “AD + CBB′” couple‐monomer approach

A series of novel hyperbranched poly(ester‐amide)s (HBPEAs) based on neutral α‐amino acids have been synthesized via the “AD + CBB′” couple‐monomer approach. The ABB′ intermediates were stoichiometrically formed through thio‐Michael addition reaction because of reactivity differences between functional groups. Without any purification, in situ self‐polycondensations of the intermediates at elevated temperature in the presence of a catalyst afforded HBPEAs with multihydroxyl end groups. The degrees of branching (DBs) of the HBPEAs were estimated to be 0.40–0.58 and 0.24–0.54 by quantitative ¹³C NMR with two different calculation methods, respectively, depending on polymerization conditions and structure of monomers. The influences of catalyst, temperature, and intermediate structure on the polymerization process and molecular weights as well as properties of the resultant polymers were investigated. FTIR, NMR, and DEPT‐135 NMR analyses revealed the branched structure of the resultant polymers. The HBPEAs possess moderately high molecular weights with broad distributions, glass transition temperatures in the range of ?25.5 to 36.5 °C, and decomposition temperatures at 10% weight loss under nitrogen and air in the regions of 243.4–289.1 °C and 231.4–265.6 °C, respectively. Among them, those derived from D ,L ‐phenylalanine display the lowest degree of branching, whereas the highest glass transition temperature and the best thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Iodine‐Catalyzed Synthesis of Spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones under Mild Conditions

The I₂‐catalyzed preparation of spiro[1,3,4‐benzotriazepine‐2,3′‐indole]‐2′,5(1H,1′H)‐diones from 2‐aminobenzohydrazide and isatins in MeCN at room temperature in good‐to‐excellent yields is described. The structure of 3 was corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS data). A plausible mechanism for this type of reaction is proposed (Scheme 2).     

Synthesis and Properties of N,N′‐Bis(difuroxano [3,4‐b:3′,4′‐d]phenyl)oxalic Amide

N,N′‐Bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide was synthesized via acylation, nitration, azidation, and pyrolysis‐denitrogenation from the starting materials of oxalyl chloride and 3,5‐dichloroaniline, under mild reaction conditions, with the yields of 81.0%, 82.0%, 86.0% and 81.7% respectively. The title compound and its precursors were characterized by ¹H NMR, IR, MS, and elemental analysis. The title compound has a density of 1.92 g·cm^?3 by a suspension method, a standard formation enthalpy of 979 kJ·mol^?1 calculated by Gaussian programs, a detonation velocity of 8.17 km·s^?1, and a detonation pressure of 31 GPa obtained by Kamlet Equation. The thermal decomposition reactions of the title compound at different heating rates were tested by differential scanning calorimetry (DSC). The kinetics parameters of the pyrolysis of the compound were calculated by Kissinger's method. The values of apparent activation energy (E_a) and pre‐exponential constant (A) were 226.7 kJ·mol^?1 and 10^23.17 s^?1 respectively. It was presupposed that N,N′‐bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide would be a promising high energetic explosive with low sensitivity.     

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.