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The synthesis of four derivatives and the single-crystal X-ray structures of six 9-trifluoromethylxanthenediols (TFXdiols)

Efficient and ambient synthesis of aromatic polyimides (PIs) from readily available starting materials remains a very challenging task in polymer chemistry. Herein, we report for the first time a r...

An experimental study on the superacid-catalyzed polyhydroxyalkylation of biphenyl (A2 monomer) and 1-propyl isatin (B2 monomer) at non-stoichiometric conditions is presented. The produced high-performance polymers were characterized by gel permeation chromatography matrix-assisted laser-desorption/ionization-time-of-flight (MALDI-TOF), nuclear magnetic resonance and diffusion-ordered spectroscopy (DOSY). High molecular weights (Mw > 150,000 Da) and ultra-high molecular weights (Mw ∼ 900,000 Da) are obtained when B2 is used in excess, which agrees with the behavior observed at non-stoichiometric conditions for other superacid catalyzed polyhydroxyalkylations, contrary to the case when A2 is used in excess, where a reduction in molecular weight is obtained, as reported in a previous study from our group. A, B, and M types of linear polymer molecules, as well as C-type cycles, were observed from the MALDI-TOF data.

Novel, linear, high-molecular-weight single-strand heteroaromatic polymers and copolymers containing 9H-xanthene moieties in the backbone were synthesized by metal-free superacid-catalyzed stoichiometric and nonstoichiometric step-growth polymerizations of carbonyl compounds bearing electron-withdrawing substituents with bisphenols. The electrophilic aromatic substitution reactions of ketones with phenol fragments occur exclusively in ortho-positions to the hydroxy phenol group and followed by highly efficient cyclodehydration reaction of hydroxyl-containing intermediates to give corresponding substituted 9H-xanthene-2,7-diyl polymers. The polymerizations were performed at room temperature in the Bronsted superacid trifluoromethanesulfonic acid (CF3SO3H, TFSA) and in a mixture of TFSA with methylene chloride and nitrobenzene.

Synthesis of processable, aromatic pyridine-containing polymers has always been a great challenge. Here, we report for the first time a robust, low-cost synthesis of well defined, high molecular weight, linear, wholly aromatic polymers with rigid ether-bond-free aryl backbones, where the proportion and position of pyridine moieties and spacer lengths between them in the macromolecules are fully controlled. The polymers, in nearly quantitative yields, were obtained by one-pot, room temperature, metal-free, non-stoichiometric superacid catalyzed step-polymerization of 4-acetylpyridine (and its mixtures with 2,2,2-trifluoroacetophenone) with multiring aromatic hydrocarbons: biphenyl, meta- and para-terphenyl, and para-quaterphenyl, in the mixture of trifluoromethanesulfonic acid with methylene chloride and trifluoroacetic acid. The polymers are highly soluble in most common solvents and form flexible and tough films with tensile strength in the range of 72–92 MPa. 1H and 13C NMR analyses of the synthesized polymers revealed high regio-selectivity of the polymer forming reaction affording linear structures with para-substitution in the phenylene fragments of the main chains. The molecular weights of the polymers ranged from 20 000 to 100 000 g mol−1, whereas the polydispersity is generally well below 2. The polymers exhibited also high thermostability with Tg > 400 °C, weight loss temperatures (N2, onset) ca. 485 °C, char yields of 70–75 at 800 °C and high chemical stability. Room temperature reactions of the polymers with methyl(trifluoromethylsulfonate) afford the N-methylated cationic polymers. Certain studies on the physical properties and gas separation of the polymers are highlighted.

Poly(oxindolylidene arylene)s (POXINARs), a family polymers with high performance in terms of thermal stability properties and with ether-bond-free aromatic backbones alternating with bulky, torsio...

This work studies useful routes to produce cross-linked poly(oxyindole biphenylylene) bearing a cross-linkable propargyl group, PNPr. Thus, the effect of cross-linking temperature and time on gas permeability and ideal selectivity for a non-cross-linked PNPr membrane to produce a cross-linked PNPr membrane is studied in detail in order to learn how more productive membranes, in terms of permeability–selectivity combinations, and membranes resistant to solvent swelling and CO2 plasticization may be produced. Systematic studies on structure/processing/property relationship assessed by Fourier transform infrared attenuated total reflectance (FTIR-ATR), gel content (GC [%]), swelling degree (SD [%]), specific volume, wide-angle X-ray diffraction (WAXD), and gas permeability measurements reveal that PNPr membranes cross-linked under vacuum (1 mmHg) at 190 °C for 24 h, and further vacuum-annealed for 1584 h, at 35 °C and 10–3 mmHg, produce membranes that overcome the typical trade-off between permeability and s...

A novel series of aromatic polyamides was synthesized by postpolymerization modification using a simple strategy to introduce different bulky pendant groups into a precursor polymer. The polyamides possess high thermostability with Tg values in the range of 298–312 °C and good mechanical properties. These polyamide membranes also exhibit enhanced gas separation performance, especially for CO2 and H2 separations, with plasticization resistance in the range tested (2.02–10.13 bar). The most remarkable result for gas permeability is attained with P3 bearing 4-tert-butylbenzoyl (TBB) as pendant group (PCO2 = 88.1, PH2 = 101 with selectivity (α) for CO2/CH4 = 19.2 and H2/N2 = 21.5). The highest permselectivity is obtained for P2 containing p-toluoyl (p-T) as pendant group (CO2/CH4 = 26.1 and H2/CH4 = 38.1).

Physical aging in amorphous polymers causes a decrease in specific volume and thus in the gas transport properties of their membranes. In this work, the effect of simultaneous thermal decomposition of a thermolabile tert-butyl carbonate group, BOC, and cross-linking by a propargyl group (−CH2–C≡CH) on the gas selectivity–permeability properties of the resulting membranes is studied to learn how membranes with mitigated variations in the gas permeability coefficients with aging time may be produced. The model copolymer is a poly(oxyindole biphenylylene) that bears BOC and propargyl groups, [(PN-BOC)x-(PN-Pr)y]n. Systematic studies on the structure/processing/property relationship assessed by TGA, DSC, and permeation measurement using pure gases reveal that a single thermal treatment for 1 h at 240 °C on a neat copolymer membrane, 12–20 μm thickness, is enough to produce chemically robust membranes (insoluble in NMP and DMSO) and that are physically more resistant to aging since the permeability reduction r...

Summary We used chemical modification to obtain new polymers that contain pyrrole units in the main chain, with electron-withdrawing groups acting as potential organic semiconductors, by means of chemical modification of the diacetylene-containing precursors. These were prepared by oxidative coupling of terminal diacetylenes or by superelectrophilic polycondensation of diphenoxydiacetylene with isatin. Diacetylenic fragments in the precursors reacted with aromatic amines that bore electron-withdrawing substituents in the presence of copper chloride, in order to yield the corresponding diphenyl-pyrrole polymers. These were then fully characterized by NMR, IR and thermal analysis. The molecular weights of the polymers were also determined by GPC. We used UV–vis spectroscopy to derive the optical band gap of the polymers. The band gap values of synthetized polymers can be modulated by modifying the position and type of substituent. Band gaps obtained in wafer form range from 1.35 to 2.8 eV; the range required for polymer semiconductors, if they are to be employed in optoelectronic devices.

In this document, we report an efficient synthesis of well-defined, soluble, high molecular weight, film-forming aromatic multifunctional homopolymers bearing two distinct functional groups per repeating unit. The polymers were obtained in nearly quantitative yields by a one-pot, room-temperature, non-stoichiometric superacid-catalyzed step-polymerization of derivatives of pyruvic acid with aromatic hydrocarbons. It was found that thin gold films (2–12 nm) sputtered onto the surface of a multifunctional homopolymer (PTBC) containing carboxy- and bromomethyl- functionalities in every repeating unit undergo spontaneous, solvent-free, room-temperature, quantitative transformation into nanoparticles. For the first time, the key factors affecting film-to-particle transformation were revealed. Internal factors are dependent on the polymer structure, its homogeneity, and the composition of the polymer/metal interface, while external factors include gold-film thickness, temperature and ageing atmosphere. By varying the functional-group combinations and aromatic fragments, a set of multifunctional homopolymers has been synthesized and it was found that the presence in the homopolymer of a repeating unit of two phenylene rings and two functional groups – bromomethyl and carbonyl – attached to the same carbon backbone atom (forming a so-called “Reactive site”) is critically important for film-particle transformation. The process is accelerated with increasing temperature, proceeds in ambient air, and is halted in a vacuum. The average grain size of the nanoparticles increased from 3 to 18 nm over a week at room temperature and from 5 to 27 nm over the same period at 40 °C. The size and shape of the nanoparticles are modulated by controlling the thickness of the gold film, the temperature and the ambient atmosphere. The transformation represents a very simple, one-step, environmentally-friendly process that is not dependent on any other chemical reagents, requires no previous temperature or high-energy processing, and can easily be scaled up to fabricate high-purity, fully accessible polymer-(film- or nanofiber-) supported gold nanoparticles of long-term stability.

Polymeric membranes are highly advantageous over their ceramic counterparts in terms of the simplicity of the manufacturing process, cost and scalability. Their main disadvantages are low stability at temperatures above 200 °C, and in organic solvents. We report for the first time porous polymeric membranes manufactured from poly(oxindolebiphenylylene) (POXI), a polymer with thermal stability as high as 500 °C in oxidative conditions. The membranes were prepared by solution casting and phase inversion by immersion in water. The asymmetric porous morphology was characterized by scanning electronic microscopy. The pristine membranes are stable in alcohols, acetone, acetonitrile and hexane, as well as in aqueous solutions with pH between 0 and 14. The membrane stability was extended for application in other organic solvents by crosslinking, using various dibromides, and the efficiency of the different crosslinkers was evaluated by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). POXI crosslinked membranes are stable up to 329 °C in oxidative conditions and showed organic solvent resistance in polar aprotic solvents with 99% rejection of Red Direct 80 in DMF at 70 °C. With this development, the application of polymeric membranes could be extended to high temperature and harsh environments, fields currently dominated by ceramic membranes.

The synthesis and properties of novel aromatic poly- and co-polyisopthalamides bearing –OH, -tert-butyl (TERT) and 3,5-bis(trifluoromethyl) benzoyl (BTFB) groups are reported. All synthesized aramides are highly soluble in aprotic solvents, thermally stable up to 400 °C and present good film forming ability. The combination at random of -OH group with TERT or BTFB groups in copolymers CPA 1 and CPA 2 is highly effective for improving gas permeability ( P ) for all tested gases (CO 2 , O 2 , N 2 , CH 4 ) and selectivity (α) for CO 2 /CH 4 and CO 2 /N 2 . Copolymer CPA 2b containing OH and BTFB groups exhibited high gas permeability and good selectivity (P CO2 =60.17 and P CH4 =2.67, α=22.53) in comparison with analogous polyamides and some polyimides. These results are well correlated with both the increase in fractional free volume (FFV) and interchain d -spacing.

Novel fluorinated aromatic polymers were obtained by one-pot, metal-free, superacid-catalyzed step-polymerization of trifluoromethylalkyl 1(a-b) and trifluoromethylaryl (1c) ketones with p-quaterphenyl (A). The room temperature polymerizations performed in a mixture of trifluoromethanesulfonic acid (CF3SO3H, TFSA) with methylene chloride gave polymeric particles. Thermogravimetric analysis for the particles revealed insignificant weight loss below 500 °C confirming their polymeric nature. Studies of solid state NMR revealed the incorporation of p-quaterphenyl in the polymer chain. The regioselectivity of polymerizations involving p-quaterphenyl and fluoroketones has been confirmed by the preparation and NMR characterization of soluble copolymers of trifluoroacetophenone (1c) with p-terphenyl/quaterphenyl mixtures. Conformational rigidity and free volume calculations confirm polymers with medium hardness and with free volumes around 0.205–0.221 cm3/g. Scanning electron microscopy show rough surfaces with pore sizes around 20–50 nm. The H2, N2 and CO2 adsorption isotherms show that these polymers may possess intrinsic microporosity making them potential molecular sieves.

The gas permeability and ideal selectivity in poly(oxyindole biphenylylene) polymers that bear a tert-butyl carbonate side group, PN-BOC, have been measured, at 35 °C and 2 bar. It is found that the thermal degradation of the thermo-labile side group, BOC, at moderate temperatures and times, is useful for designing membranes that overcome the typical trade-off between permeability and selectivity. TGA, FTIR-ATR, and DSC analysis reveal that thermal treatments of PN-BOC at 150 °C and short periods of time, 5–60 min, allow the design of membranes with better selectivity–permeability combinations than the pure PN-BOC precursor. For the gas pairs O2/N2 and CO2/N2, the PN-BOC5 thermally treated membranes for 5 min show O2 and CO2 permeability coefficients higher by a factor of 2.3 with respect to that measured in PN-BOC, while retaining their selectivity. For the gas pairs H2/CH4 and CO2/CH4, the PN-BOC60 thermally treated membranes for 60 min show a H2 and CO2 permeability coefficient higher by a factor of 1....

The effect on the J–V behavior of polymer solar cells (PSCs) based on the active layer PTB7:PC71BM under a previous application of an external electric field (Eext) is presented. The active layer is doped with 0.01–0.04 wt. ratio (with respect to PTB7) of poly(9-vinylcarbazole) (PVK) as a photoconductor, and/or 0.25–0.5 wt. ratio of 9-ethylcarbazole (ECZ) as plasticizer. The general PSC structure was Glass-ITO/PEDOT:PSS/PTB7:PC71BM:dopant/PFN/FM where dopant means PVK, ECZ or a mixture of them. Field’s metal (FM) is an eutectic alloy with a melting point above 62 °C, which is deposited in a vacuum free atmosphere. Electric fields of 5 or −70 V/μm (forward and reversed polarity, respectively) are applied. For PSCs doped with PVK, under forward polarity, it is observed a remarkable variation (36 %) on Jsc: from 7.7 to 4.9 mA/cm2, while Voc remains almost constant: ~0.76 V; whereas with the reversed polarity, a drastic variation of 95 % is observed on Voc: from 0.76 to 0.04 V; while Jsc value changes from 7.4 to 5.6 mA/cm2 (24 %). On the other hand, PSCs doped with the combination of ECZ and PVK, an increase of 10 % in Jsc is reached for reversed bias (Eext = −70 V); and without applying any field, and keep them under N2 atmosphere, a slower photovoltaic degradation, with respect to that one from all the other studied samples, is shown over 57 days of monitoring them: FF variation is of just 6 % and PCE decays only 21 %.

Three novel fluorinated polymers with ether-bond-free aryl backbones were obtained by one-pot, metal-free, room temperature superacid catalyzed non-stoichiometric step polymerization of 1,1,1-trifluoromethyl acetone with carbazole (CBZ), fluorene (FLN) and 9,9-dimethylfluorene (DFL). 1H and 13C NMR analyses of the polymers revealed their linear structure and high regioselectivity of the polymer forming reaction. The polymers also possess high thermostability with decomposition temperature up to 387 °C for CBZ and up to 530 °C for FLN and DFL as well as reasonable mechanical properties. The gas transport properties of six pure gases and binary gas mixture CO2/CH4 (10/90 mol%) are reported. These polymers present a good combination of permeability and selectivity up to 10 bar at 35 °C for CO2/CH4 mixed-gas feed. DFL exhibits the best pure-gas permeability and selectivity (PCO2 = 78.0, PH2 = 151.5, CO2/CH4 = 22.3 and H2/CH4 = 43.3) and mixed-gas permeability and selectivity CO2/CH4 (PCO2 = 71.3, CO2/CH4 = 23.7) at 35 °C and 2 bar with a slight decrease in selectivity at 10 bar. The highest permselectivity is obtained for FLN (CO2/CH4 = 36.7 and H2/CH4 = 88.4) with a separation performance close to the 2008 upper bound trade off.

Organic light emitting diodes (OLEDs) based on a new polymer; are reported. This new polymer; Poly[(Benzo[c] [1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl))-3,3-diyl(1-(3-(trifluoromethyl)phenyl)-2-oxindole)] (PF-2F), was used as emissive layer (EML), with a relatively simple architecture ITO/PEDOT:PSS/polymer/(LiF or PFN)/A, which is a modified version of our previously reported; PF-1: Poly[(Benzo[c] [1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl(1-phenyl-2-oxindole)], applied in OLEDs and lasing devices. The main difference between these two polymers, is the trifluoromethyl (CF3) group addition to the PF-2F. CF3 leads to improved OLEDs electroluminescence and better EQEmax; due to enhanced mechanical properties, higher solubility and higher fluorescence quantum yield (FLQY). PF-1 and PF-2F polymers have an excellent FLQY: ~1. Polymer films (by spin coating) show low roughness value (~1–2 nm), just like polymers in OLEDs. OLEDs based on the modified polymer (with yellow-green electroluminescence (EL) emission) showed luminances of up to 1937 cd/m2, current efficiencies of up to 35 cd/A and maximum external quantum efficiency (EQEmax) of up to 2.6%. Additionally, promising preliminary results on flexible OLEDs using PF-2F and PEDOT: PSS conductive (PH1000) (as anode) are reported.

In this work, OLEDs based on a new modified polymer PMC 300* (as emissive layer: EML) were manufactured with the structure ITO/PEDOT:PSS/Polymer (PMC 300*)/LiF or PFN/Al. This new polymer PMC 300*: Poly[(Benzo[c][1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl))-3,3-diyl(1-(3- (trifluoromethyl)phenyl)-2-oxindole)], is a modified version of PF-1 polymer that was synthesized and used previously in our group for non-linear optical properties and in OLED devices. The CF3 additional group on PMC 300* showed an improved electroluminescence and current efficiency on OLED devices. PF-1 and PMC 300* polymers have a fluorescence quantum yield (FLQY) of approximately 1. Film formation of the hole injection layer (HIL) and the EML were made by spin coating and subsequently evaporating LiF (or PFN by spin coating) and Al as cathode. Polymer films show a very low roughness (~ 1-2 nm), as most of the polymers used in OLEDs. Due to PMC 300* excellent properties like high solubility, very high QY, high conjugation and mechanical characteristics, OLEDs based on this new modified polymer (with emission in green-yellow wavelengths) showed luminances up to 1937 cd/m2, high current efficiencies of 35 cd/A and a maximum external quantum efficiency (EQEmax) of 2.6 %. Additionally, preliminary tests of flexible OLEDs by using this polymer are currently carrying out, results are promising.

A novel series of linear, high-molecular-weight polymers and copolymers were synthesized by one-pot, metal-free superacid-catalyzed polymerization of aliphatic 1,2-diketones (2,3-butanedione (1a), 2,3-hexadione (1b), 3,4-hexadione (1c), 2,3-butanedione monoxime (1d), pyruvic acid (1e), 1,4-dibromo-2,3-butanedione (1f), 2-bromopyruvic acid (1g), and methyl-3,3,3-trifluoropyruvate (1h) with linear, nonactivated, multiring aromatic hydrocarbons terphenyl (A), biphenyl (B), fluorene (C), and N-ethyl carbazole (D). Depending on the reaction system, the polymerizations were carried out as stoichiometric or non stoichiometric, with direct or inverse monomer addition. Copolymers were obtained by polymerization of 1,2-diketones with a mixture of aromatic hydrocarbons. In the course of the polymerization only one carbonyl group of a 1,2-diketone reacts to form C–C bonds with aromatic fragments while the other functional groups (including the second carbonyl group) are incorporated unchanged into polymer chain. The ...

This work presents the results of polymer membranes whose permeability and selectivity combination of properties can be defined through the chemical modification, in the solid state, of the repeating unit of a poly(oxindolebiphenylyene) that bears a −CH2OH group, PN–CH2OH. The chemical modifications are promoted by moderate thermal treatments (160–180 °C) and short times (

A novel series of linear, high-molecular-weight polymers and copolymers was synthesized by one-pot, metal-free superacid-catalyzed reaction of trifluoromethylalkyl (1a-1c) and trifluoromethylaryl (1d-1h) ketones with the linear, nonactivated, multiring aromatic hydrocarbons biphenyl (A), p-terphenyl (B), and p-quaterphenyl (C).The polymerizations were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CF3SO3H, TFSA) and in a mixture of TFSA with methylene chloride. Polymerizations of trifluoromethyl ketones (1c, 1f-1h) bearing functional groups gave polymers with reactive lateral groups such as bromomethyl, 4-(N,N-dimethylamino)phenyl-, 3-sulfophenyl-, and 2,3,4,5,6-pentafluorophenyl. The polymers obtained were soluble in most common organic solvents and flexible transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear structure with para-substitution in the phenylene fragments of the main chain. The molecular weights (Mw) of the polymers based on trifluoromethylalkyl ketones and aromatic are very high and reach 1 000 000, while the molecular weights of the polymers based on trifluoromethylaryl ketones and aromatic ranged from 30 000 to 300 000 g/mol. The polydispersity of the polymers is generally less than 2. The polymers also possess high thermostability. Mechanistic aspects of polymerization mechanism have been discussed, and a new approach for monomer design has been proposed. © 2013 American Chemical Society., Financial support from CONACYT Mexico (Grant 151842) and from DGAPA-UNAM (PAPIIT IN 104211)

Metal nanoparticles have unusual optical, electronic, sensing, recognition, catalytic, and therapeutic properties. They are expected to form the basis of many of the technological and biological innovations of this century. A prerequisite for future applications using nanoparticles as functional entities is control of the shape, size, and homogeneity of these nanoparticles and of their interparticle spacing and arrangement on surfaces, between electrodes, or in devices. Here, we demonstrate that thin films of gold, silver, and copper sputter-deposited onto the surface of an organic polymer poly[[1,1':4',1″-terphenyl]-4,4″-diyl(2-bromo-1-carboxyethylidene)] (PTBC) undergo spontaneous solid-solid transformation into nanoparticles. Furthermore, we show that, by varying the thickness of the films, the volume-to-surface ratio of the polymer substrate, and the amount of plasticizer, it is possible to control the rate of transformation and the morphology of the nanoparticles formed. PTBC containing Au nanoparticles was found to enhance the cell adhesion and proliferation. To the best of our knowledge, our findings constitute the first experimental evidence of spontaneous, room-temperature, solid-solid transformation of metal films sputtered onto the surface of an organic polymeric substrate into nanoparticles (crystals).

Light emission properties of a fluorene cross-conjugated polymer (PF–1) based on the monomer 4,7-bis[2-(9,9-dimethyl)fluorenyl] benzo[1,2,5]thiadiazole are reported. This polymer exhibits solubility at high concentrations, good processability into thin solid films of good quality and a broad emission band with a fluorescence quantum yield of approximately 1. Based on these features, in this paper we implemented the use of PF–1 as an active layer in polymer light-emitting diodes (PLEDs) and as a laser gain medium in solution. To get insight on the conducting properties of PF–1, two different electron injectors, poly [(9,9-bis(3′-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9–dioctylfluorene)] (PFN) and lithium fluoride (LiF), were used in a simple PLED architecture. PLEDs with the PFN film were found to exhibit better performance with a maximum luminous efficiency of 40 cd/A, a turn-on voltage (Von) of approximately 4.5 V and a luminance maximum of 878 cd/m2 at 5.5 V, with a current density of 20 A/m2. For the lasing properties of PF–1, we found a lasing threshold of around 75 μJ and a tunability of 20 nm. These values are comparable with those of rhodamine 6G, a well-known laser dye.

A reliable and practical approach is offered for the two critical fundamental challenges that remain in step-growth polymerization: synthesis of narrow polydispersity and ultrahigh molecular weight polymers. The polymers are obtained by superacid catalyzed polyhydroxyalkylation involving two consecutive steps – slow and fast. Polymer syntheses with decrease in reactivity of intermediates lead to narrow polydispersity polymers, while nonstoichiometric reactions result in polymers of high and ultrahigh molecular weight. Linear aromatic polymers with ultra high molecular weight Mn > 1 000 000 and narrow polydispersity (Mw/Mn = 1.15–1.16) have been obtained. An unusual step-selective mechanism is suggested for the formation of these polymers.

Super acid catalysis offers the syntheses of a rich variety of similar but different polymer structures otherwise not easily attainable. By this synthetic method, a set of 22 polymers was prepared and their gas permeability coefficients for pure gases, with their associated ideal selectivity, were measured. An analysis of their selectivity and permeability combination protocol revealed that their membranes have combinations, specifically for the O 2 /N 2 , CO 2 /CH 4 and CO 2 /N 2 separations, that are in the same order of magnitude as those reported for the polysulfone and some polyimide families. For CO 2 /N 2 separations, polymers CF 3 PhSO 3 H-T and CF 3 Ph-T offer membranes with CO 2 permeability coefficients of 83 and 220 Barrer, with corresponding selectivity of 31 and 24 . In addition, by the systematic incorporation of Me, Ph, flouro atoms or CF 3 groups into their chemical structure it is possible to understand the structure/properties relationship of gas transport for this series of polymers.

Complementary theoretical and experimental studies of the consecutive steps of superacid catalyzed polyhydroxyalkylation reactions have been carried out. Calculations for the superacid catalyzed polyhydroxyalkylation of trifluoroacetone and trifluoroacetophenone with aromatic hydrocarbons explained a number of experimental facts within a single theoretical framework of monoprotonation. The principal factors affecting kinetics of superacid mediated hydroxyalkylation were shown to be as follows: (i) the acidity of the superacid affecting protonation energy of carbonyl components; (ii) the electrophilicity of carbonyl components; and (iii) the nucleophilicity of aromatic components. The modification of those factors allows for tuning of the reactivity of carbonyl and aromatic components; thereby, reaction kinetics are controlled. The conclusions were confirmed by the experiments. Theoretically predicted stoichiometrically imbalanced polymerizations of trifluoroacetone, trifluoroacetophenone, octafluoroacetop...

Linear oligomerization of 3,5-dimethyl benzyl alcohol is induced by a montmorillonite clay (Tonsil Optimum Extra), producing 1,3,5,7-tetramethyl-9,10-dihydro-anthracene, which, by loss of protons results in the product 1,3,5,7-tetramethylanthracene. It was also found that the compounds 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetramethyl-9,10-dihydroanthracece and 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetra-methylanthracene were formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene. 1,3,5,7-Tetramethylanthryl radical cation was formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene, it was characterized by Electronic Paramagnetic Resonance (EPR). On the other hand, a theoretical analysis was performed, allowing the rationalization of the observed products and some of the key reaction steps.

A novel series of linear, high-molecular-weight polymers was synthesized by one-pot, metal-free superacid-catalyzed reaction of isatins (1a−d) with linear, nonactivated, multiring aromatic hydrocarbons: biphenyl (A), p-terphenyl (B), p-quaterphenyl (C), 2-(4-biphenylyl)-6-phenylbenzoxazole (D), 9H-fluorene (E), 9,9-dimethyl-9H-fluorene (F), 2,2′-[2,5-bis(trifluoromethyl)-1,4-phenylene]bis(9,9-dimethyl-9H-fluorene) (G), oligo-9,9-bis(2,6-ethylhexyl)-9H-fluorene (H), biphenol (I), and bi-2-napththol (J). The reactions were performed at room temperature in the Bronsted superacid trifluoromethanesulfonic acid (CF3SO3H, TFSA) and in a mixture of TFSA with methylene chloride or TFA tolerant of hydroxyl, carboxy, and cyano groups. The polymers obtained were soluble in most common organic solvents, and flexible transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear structure with para-substitution in the phenylene fragments of the main chain. ...

We designed and synthesized two novel fluorene monomers of D – A – D (donor–acceptor–donor) type ( M1 and M2 ), and their two corresponding polymers ( PM1 and PM2 ) and a copolymer ( CPM ). These high molecular weight, film-forming polymers were obtained from metal-free, superacid-catalyzed reactions of the monomers with N -phenylisatin. The cubic NLO response ( χ (3) ) for these new compounds, in solid thin films, was measured through the use of third-harmonic generation (THG) Maker-Fringes technique at IR wavelengths given values of the order of 10 −12 esu from which, the corresponding second hyperpolarizabilities ( γ ) were estimated to be of the order of 10 −33 esu for monomers and 10 −31 esu for polymers. Second hyperpolarizabilities have also been estimated theoretically at B3LYP/6-31G(d) level of theory in gas phase and related with the electronic structure of the synthesized molecules.

Energies of mono- and multiprotonation for 1,2,3-indanetrione and ninhydrin in triflic acid (TFSA) media were estimated at PBE0/aug-cc-pvtz//6-31+G** level of theory. The reactivity of formed intermediates in the reaction of aromatic electrophilic substitution has been studied at the same level of theory. It appears that the basicity of carbonyl groups in 1,2,3-indanetrione is extremely low due to mutual influences of carbonyl groups. Carbonyl 2 is the least basic but the most reactive in accordance with experiment. Calculations demonstrated that monoprotonated intermediates are the principal reactive species in the reaction of hydroxyalkylation of 1,2,3-indanetrione in TFSA. A new isomerization mechanism of 2,2-diaryl-1,3-indanediones to 3-(diarylmethylene)isobenzofuranones in TFSA media has been proposed. Copyright © 2010 John Wiley & Sons, Ltd.

A systematic study was undertaken of the EPR of sodium hydroxide solutions of Benzoin, Anisoin and Thenoin in both ethanol and DMSO as well as their corresponding ionised species of varying colours. In all cases, the EPR consist of symmetric spectra, resulting from the generation of a free radical-anion. Furthermore, theoretical DFT methods were applied in order to study the radical anions, revealing the reason for the colour change in the solutions and in the case of benzoin, found to be related to the interaction between the cis and trans-isomers with the molecules in the two solvents. We have defined the structure of the cis-isomer and for the first time we have described how the adduct between the cis-isomer and the solvent molecule, results in a stable conformer. This corresponds with the EPR results which indicated a significant difference between the cis and trans-isomers. Both the theoretical and experimental results inspired similar descriptions of the significant differences between the cis and trans-isomers in solution.

New polysulfone (PSF) copolymers from bis(4-fluorophenyl)sulfone and based on equimolar mixtures of the rigid/compact naphthalene moiety with bulky connectors from bisphenols: tetramethyl, hexafluoro, and tetramethyl hexafluoro, respectively, were synthesized to measure significant physical properties related to the gas separation field. The flexible and transparent polymer dense films TM-NPSF, HF-NPSF and TMHF-NPSF show high glass transition temperatures Tg congruent to 230 degrees C and high decomposition temperatures To congruent to 400 degrees C (10wt.% loss, in air). Free volume cavity sizes, as determined by PALS, are in the range of 94-139 angstrom(3). Their gas permeability and selectivity combinations of properties, measured at 35 degrees C and 2 atm, are very attractive since their selectivity for the pair of gases H-2/CH4,O-2/N-2, and CO2/CH4 are higher than those for commercial PSF membranes, having similar or superior permeability coefficients for the most permeable gases H-2, O-2, and CO2. Especially important is the tetramethyl naphthalene polysulfone TM-NPSF membrane which reports selectivities for H-2/CH4, O-2/N-2 and CO2/CH4 of 122, 7.6 and 38 with corresponding permeability coefficients (in Barters) of 17 for H-2, 1.2 for O-2, and 5.2 for CO2. These results are interpreted in terms of free volume size and glass transition temperature together with the respective contribution of gas solubility and diffusivity to the overall selectivity coefficients. (C) 2009 Elsevier B.V. All rights reserved.

The stability and reactivity of mono- and multi-protonatred N-substituted isatin derivatives were studied at PBE0/aug-cc-pvtz//PBE0/6-31+G** level of theory in triflic acid (TFSA) solution. Calculations showed that the monocationic intermediates are the principal reactive species in the reaction of hydroxyalkylation of isatin derivatives in TFSA media. Electron-withdrawing substituents on the nitrogen atom increase the reactivity of isatin-containing electrophiles towards aromatic hydrocarbons, in accordance with their expected electronic influence. Steric factors also play an important role in the reactivity of isatin-containing electrophiles, especially in the second reaction step, due to their more sterically hindered reactive center.

A novel series of linear, high-molecular-weight polymers was synthesized by one-pot, superacid-catalyzed reaction of pentafluorobenzaldehyde (PFBA) (1) with nonactivated aromatic hydrocarbons: biphenyl, diphenyl ether, p-terphenyl, 4,4′-diphenoxybenzophenone, and 1,3-bis- and 1,4-bis(4′-phenoxybenzoyl)benzenes. The reactions were performed at room temperature in the Bronsted superacid trifluoromethanesulfonic acid (CF3SO3H, TFSA) and in a mixture of TFSA with methylene chloride. The polymer-forming reaction was highly dependent upon the acidity of the reaction medium, as judged from the molecular weights of the polymers obtained. A possible reaction mechanism is suggested. The polymers obtained were soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear structure. The pendent pentafluorophenyl groups react regioselectively with nucleophiles under basic conditions in polar, aprotic so...

New aromatic 3F polymers were obtained from condensations of 2,2,2-trifluoroacetophenone (1) with biphenyl (a), terphenyl (b), a mixture of biphenyl with terphenyl (ab), phenyl ether (c) and diphenoxybenzophenone (d). The reactions were performed at room temperature in the Bronsted superacid trifluoromethanesulfonic acid (TFSA) and in a mixture of TFSA with dichloromethane. The polymers show high glass transition temperatures >170 °C, excellent thermal stability (decomposition temperatures ≥475 °C) and good solubility in chlorinated solvents and strong acids. The 3F polymer structures based on biphenyl and terphenyl show attractive permeability coefficients for CO2 (∼200 Barrers) and H2 (∼120 Barrers), whereas the 3F polymers that contain ether linkages have permeability coefficients in the typical range of regular polysulfone and polycarbonate. However, in sharp contrast to polysulfone and polycarbonate families, new 3F polymers possess high chemical stability and they have advantages since their reactions, based on commercially available monomers, can be carried out in one-pot at room temperature and offer a large variety of structures not possible to prepare by other synthetic methods.

A novel series of linear, high molecular weight high performance and functional polymers were synthesized by a one-pot, superacid-catalyzed polyhydroxylakylation reaction of carbonyl compounds containing electron-withdrawing substituents, adjacent or relatively close to a carbocation center with non-activated aromatic hydrocarbons. The reactions were performed at room temperature in the Brønsted superacid CF3SO3H (trifluoromethanesulfonic acid, TFSA) and in a mixture of TFSA with methylene chloride, which was used as both solvent and a medium for generation of electrophilic species from the carbonyl component. Polycondensations of 1,1,1-trifluoroacetone, 2,2,2-trifluoroacetohenone, 2,7-dinitrofluorenone, acenaphthenequinone and isatin with aromatic hydrocarbons proceed readily in the presence of superacid at room temperature. The polymers obtained were found to be soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. 1H and 13C NMR analyses of the polymers synthesized revealed their linear, highly regular structure. The polymers also possess high thermostability.

Mono- and diprotonated reaction intermediates involved in the acid-catalyzed polyhydroxyalkylation of aldehydes and ketones of the general formula R 1 COR 2 , (R 1 =H, CH 3 , CF 3 and R 2 =Ph, CH 3 , CF 3 ) with benzene and biphenyl, were studied theoretically at PBEO/aug-cc-PVTZ//PBEO/6-31+G** level of theory. The calculations performed for sulfuric acid and TFSA-catalyzed reactions showed that for all studied reactions the enhancement of the reactivity of diprotonated species is not sufficient to compensate for the large positive Gibbs energy of second protonation. An alternative mechanism has been proposed for the reaction between benzene and benzaldehyde in TFSA involving only monoprotonated species. The low reactivity of carbonyl compounds with electron donating substituents is due to excessive stabilization of monoprotonated species rendering the reaction thermodynamically impossible.

A series of novel, linear, soluble, high-molecular-weight, fluorinated aromatic polymers has been obtained for the first time using a superacid-catalyzed polyhydroxyalkylation reaction of fluorinated carbonyl-containing compounds: 1,1,1,-trifluoroacetone (1), 2,2,2-trifluoroacetophenone (2), 2,3,4,5,6,-pentafluorobenzaldehyde (3), and octafluoroacetophenone (4) with aromatic hydrocarbons such as biphenyl (a), phenyl ether (b), terphenyl (c), and 4,4'-diphenoxybenzophenone (d). These Friedel-Crafts-type aromatic electrophilic substitution reactions are performed at room temperature in trifluoromethane sulfonic acid or in its mixtures with dichloromethane. The polymers obtained are soluble in common organic solvents, and colorless transparent films could be cast from the solutions. 1 H and 13 C NMR analyses of the polymers synthesized reveal their linear, highly regular structure. The polymers also possess high thermostability.

New cardo poly(aryl ether ketone)s containing side phthalide groups and aryl ether ketones in different lengths have been synthesized and characterized in terms of their thermal, volumetric and gas transport properties to H 2 , O 2 , N 2 , CH 4 and CO 2 . The polymers show high glass transition temperature (218–420 °C), good solubility in chlorinated solvents and strong acids as well as excellent thermal stability (decomposition temperatures above 510 °C). The most permeable membrane studied shows permeability coefficients of 11 to O 2 and 72 to CO 2 , with ideal selectivity factors of 4.6 for the pair O 2 /N 2 and 25 for CO 2 /CH 4 . The results, interpreted in terms of chain rigidity and chain packing ability, show that decreasing the length of the connector moieties between the cardo groups increases the fractional free volume, the glass transition temperature and the gas permeability coefficients.

New polymers containing pyrrole units in the main chain were obtained by chemical modification of diacetylene-containing polymers, which were prepared by oxidative coupling of terminal diacetylenes or superelectrophilic polycondensation of diphenoxydiacetylene with isatin. Diacetylenic fragments in the polymers thus obtained reacted with aromatic amines in the presence of copper chloride to yield the corresponding pyrroles. The reaction between diacetylenic compounds and amines was studied to determine the proper reaction conditions for introduction of pyrrole groups into the polymer backbone. The new polymers and their model compounds were fully characterized by NMR, IR and thermal analysis.

A pH controllable molecular “shuttle,” comprising of dibenzo24crown-8 (DB24C8) macroring bound to a “finger” molecule possessing two different recognition sites has been studied at the density functional theory (DFT) and Moller-Plesset second-order (MP2) levels of theory. The calculation confirmed experimental results that translational conformer with DB24C8 located around NH station has the lowest energy, while the conformer with DB24C8 located around NH station shows the highest energy. It has been found that Bpym2+ unit consists of two “substations” separated by an energy barrier of 3–17 kcal/mol depending on the state of the NH–NH station. The translational conformers are stabilized by NH…O, +NH…O, +NCH…OH-bonds, and π–π stacking with different contributions, depending on the conformer type. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem 2007

For the first time possible reaction pathways of superelectrophilic polycondensation of 2,2,2-trifluoroacetophenone and biphenyl in trifluoromethanesulfonic acid (TSFA) have been studied theoretically at B3LYP/aug-cc-pvtz(-f)//B3LYP/6-31G* level. The reaction graph reveals the existence of four different reaction routes for polycondensation process. The analysis of the reaction pathways shows that kinetically most favorable pathway involves the successive reaction between protonated 2,2,2-trifluoroacetophenone and neutral oligomers. The reactivity indexes best correlated with calculated thermodynamic and kinetic parameters are these based on the energy difference between the ionization potential of a nucleophile and the electron affinity of a electrophile showing correlation coefficients up to 0.95. These reactivity indexes can be successfully used for the prediction of the most favorable reaction pathways in the superelectrophilic polycondensation. The calculations established basic rules for efficient design of monomers for superelectrophilic polycondensation.

A novel series of linear, high molecular weight polymers were synthesized by one-pot, superacid-catalyzed reaction of acenaphthenequinone (1) with aromatic hydrocarbons. The reactions were performed at room temperature in the Bronsted superacid CF3SO3H (trifluoromethanesulfonic acid, TFSA) and in a mixture of TFSA with methanesulfonic acid (MSA) and trifluoroacetic acid (TFA), which was used as both solvent and a medium for generation of electrophilic species from acenaphthenequinone. The polymer-forming reaction was found to be dependent greatly on the acidity of the reaction medium, as judged from the viscosity of the polymers obtained. Polycondensations of acenaphthenequinone with 4,4‘-diphenoxybenzophenone (f), 1,3-bis(4-phenoxybenzoyl)benzene (g), 1,4-bis(4-phenoxybenzoyl)benzene (h), 1,10-bis(4-phenoxyphenyl)decane-1,10-dione (i), 2,6-diphenoxybenzonitrile (j), 2,6-diphenoxybenzoic acid (k), and 2-(4-biphenylyl)-6-phenylbenzoxazole (l) proceeded in a reaction medium of wide range of acidity, includi...