ANS fluorescence as a tool to monitor cross-linking polymerization of acrylamide

A method based on monitoring the fluorescence intensity of 1-anilinonaphthalene-8-sulphonate (ANS) has been introduced to follow the cross-linking polymerization of acrylamide initiated by ammonium persulfate-TEMED redox initiator system. There is about a 20-fold increase in the fluorescence intensity of ANS accompanying polymerization. Preferential location of ANS molecules near the hydrophobic regions of the polymer surface appears to explain the fluorescence intensity enhancement. The method is found to be consistent with the conventional dilatometric method.     

Strain-promoted azide-alkyne cycloaddition polymerization as a route toward tailored functional polymers

The preparation of polymers under mild conditions, using highly efficient reactions, allows the incorporation of new, functional monomer units. Here, we explore the use of strain-promoted azide-alkyne cycloaddition (SPAAC) as a polymerization tool. We show that a polymer library with diverse thermal and stimulus-responsive properties can be rapidly prepared in minutes. This polymerization proceeds without heating or the addition of catalyst, which enables the preservation of sensitive moieties, such as stimulus-responsive spiropyran structures. Solid- and solution-state stimulus-responsiveness from these sensitive groups are demonstrated within the SPAAC-polymerized products.     

Highly Active La(III)-Based Metal-Organic Framework as a Heterogeneous Lewis Acid Catalyst for Friedel-Crafts Alkylation

In this study, a novel La(III)-based two-dimensional (2D) metal-organic framework, [La_2/3(qptca)_1/2] (referred to as SLX-2), from LaCl₃ and 1,1′ : 4′,1′′ : 4′′,1′′′ : 4′′′,1′′′′-quinquephenyl]-2,2′′,2′′′′,5′′-tetracarboxylic acid (H₄qptca) was synthesized by conventional solvothermal method and thoroughly characterized by using X-ray single-crystal diffraction, powder X-ray diffraction, and thermogravimetric analyses. The 2D SLX-2 features a unique lanthanum center exposed to the skeleton and was used as an efficient Lewis acid catalyst for the Friedel-Crafts alkylation of indole and pyrrole with β-nitrostyrene along with a wide substrate scope, giving the desired products in good-to-high yields under the optimal reaction conditions. Furthermore, the catalyst was used for twenty cycles, with nearly no effect on its activity, and the reaction was heterogeneous in nature. Moreover, compared to the previous hydrogen-bond-donating MOF catalysts for such alkylation reactions, SLX-2 showed an excellent stability toward harsh acidic and basic environment, and gave comparable catalytic activities.     

A novel pyrrolidinium ionic liquid with 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoroethoxy)ethanesulfonate anion as a recyclable reaction medium and efficient catalyst for Friedel-Crafts alkylations of indoles with nitroalkenes

A series of pyrrolidinium-based salts with new fluorine-containing anions were synthesized. Different melting points could be obtained by changing the length of the fluoroalkyl chain of the anions. The pyrrolidinium 1,1,2,2-tetrafluoro-2-(1,1,2,2-tetrafluoroethoxy)ethanesulfonate ([C₄H₈NH₂][H(CF₂)₄O(CF₂)₂SO₃]) is highly fluid even below room temperature. It can be used both as a recyclable solvent and as an efficient catalyst for Friedel-Crafts alkylations of indoles with nitroalkenes.     

Ball milling: a green mechanochemical approach for synthesis of Ni (II), Co (II) and Cu (II) complexes

A series of Ni (II), Co (II) and Cu (II) complexes were synthesized with excellent yields via a one‐pot ball milling chelation reaction of those metals and β‐diketone. The process offers numerous advantages, such as better yield, short reaction time and mild reaction conditions. The computational studying was estimated to approve the geometry of the isolated solid compounds by applying density functional theory. The synthesized compounds were interpreted by using various spectroscopic techniques [infrared (IR), ¹H‐NMR, ¹³C‐NMR, UV–visible, electron spin resonance (ESR) and mass spectrometry] together with some physical studies (molar conductance and magnetic susceptibility). The outcomes data displayed that the (HD¹), (HD²) and (HD³) acted as neutral and/or mononegative bidentate ligands. The ESR as well as electronic spectra suggested the octahedral configuration for all isolated complexes, expect [Cu (HD2)(OAc)2]·2H₂O has square planar structure. Also, the in vitro antimicrobial assay was done by using the well diffusion method for HD¹, HD², HD³ and their complexes.     

Direct arylation polymerization toward ultra‐low bandgap poly(thienoisoindigo‐alt‐diketopyrrolepyrrole) conjugated polymers: The effect of β‐protection on the polymerization and properties of the polymers

Direct arylation polymerization between derivatives of dibromodiketopyrrolopyrrole (DPP) and thienoisoindigo (TIIG) resulted in two π‐conjugated copolymers with average molecular weights up to 24.0 kDa and bandgaps as low as 0.8 eV. The structural analysis of the obtained two polymers revealed well‐defined alternating conjugation backbones without obvious structural defects. The introduction of hexyl‐group in the β‐position of thiophene rings in the DPP units not only reduces the bandgap of conjugated polymer compared to a similar polymer containing bare‐thiophene flanked DPP but also affects polymer morphology in thin films. P‐type charge‐transport characteristics were observed for two polymers in organic field‐effect transistors with comparable hole mobilities. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3205–3213     

Application of the Doehlert experimental design to molecularly imprinted polymers: surface response optimization of specific template recognition as a function of the type and degree of cross-linking

We propose the use of Doehlert’s experimental design, a second-order uniform shell design, for the optimization of molecularly imprinted polymers (MIPs). We have chosen a simple model system where the influence of kind and degree of cross-linking on template recognition was studied using S-propranolol as the template. We found that Doehlert’s design allows—with very few experiments—one to screen the evolution of the binding capacity of a MIP as a function the different parameters, and thus appears to be a powerful means to screen for the best composition and synthesis method for MIPs. We believe that this chemometric tool can significantly accelerate the development of new MIPs as synthetic recognition elements, particularly in the context of a given application, and will be a versatile complement or alternative to first-order designs to fit complex processes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Influence of functionality on direct arylation of model systems as a route toward fluorinated copolymers via direct arylation polymerization (DArP)

A screening of direct arylation conditions on a model small molecule system is carried out to develop suitable conditions for the direct arylation polymerization (DArP) of fluorinated copolymers, which are incompatible with conditions previously utilized successfully for nonfluorinated systems. The model system features a coupling between a 2‐substituted thiophene and a pentafluorobenzene, where one of the partners was brominated. A substantial difference in reactivity is observed, demonstrating that the optimal functionalization for direct arylation between a thiophene‐based donor and a highly fluorinated acceptor is a halogenated thiophene and an unfunctionalized fluorinated unit, which is opposite of typical cross coupling reactions, where the acceptor is typically halogenated. The best conditions are applied to the copolymerization of 1,2,4,5‐tetrafluorobenzene and 2,2'‐(2,5‐bis((2‐hexyldecyl)oxy)?1,4‐phenylene)dithiophene. Polymers are free of β‐defects and significant homocoupling. This work further underscores the attractive simplicity, relevance, and ease of DArP while reconfirming its broad compatibility with increasingly popular fluorinated copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2598–2605     

The organic ligands as template: the synthesis, structures and properties of a series of the layered structure rare-earth coordination polymers

A series of new 2D-layered structural rare-earth coordination polymers with the general formal [Ln(C₈H₄O₅)(H₂O)₅]·(H₂O)·(C₈H₄O₅)_1/2 (Ln=Eu for (1); Gd for (2); Tb for (3); Dy for (4); and Er for (5)) have been yielded by hydrothermal synthesis. The coordination polymers crystallize in monoclinic space group C/2c with a=19.838(16), b=10.529(8), c=17.752(14) Å, β=107.503(14)° for (1), with a=19.823(7), b=10.552(4), c=17.762(6) Å, β=107.443(6)° for (2), with a=19.770(4), b=10.519(2), c=17.698(4) Å, β=107.52(3)° for (3), with a=19.632(2), b=10.492(2), c=17.617(3) Å, β=107.470(12)° for (4), with a=19.648(7), b=10.480(3), c=17.598(6) Å, β=107.502(6)° for (5), respectively. And the metal ions (Ln³⁺) are located in nine-member coordination environment. The carboxyl groups from 5-hydroxyisophthalate chelate the metal ions to form 1D helical cation chains. It is interesting that these helical cation chains are arranged to form 2D anion–cation layers by the uncoordinated ligands' anions as template. And the luminescence properties of the rare-earth ions are studied in the paper.     

The suzuki–heck polymerization as a tool for the straightforward obtainment of poly(fluorenylene‐vinylene) sensitizers for dye‐sensitized solar cells

This article describes the synthesis and properties of the first poly(arylene‐vinylene)‐based sensitizers for application in dye‐sensitized solar cells (DSSC). The polymers were prepared by the Suzuki–Heck copolymerization of potassium vinyltrifluoroborate (PVTB) with a mixture of dibromoaryl comonomers designed to obtain macromolecules able to bind onto the photoelectrode by means of carboxyphenylene units. The copolymerization reactions were carried out in the presence of an excess of PVTB to lower the molecular weights of the polymers, which were obtained as soluble materials. The polymers poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene] ( P1 ), poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐(4,7‐benzothiadiazolylene)‐vinylene] ( P2 ), and poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐2,5‐thienylene‐vinylene] ( P3 ) were used in DSSC devices, obtaining conversion efficiencies up to 0.88% ( P3 ). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and cationic ring-opening polymerization of mono- and bifunctional spiro orthoesters containing ester groups and depolymerization of the obtained polymers: An approach to chemical recycling for polyesters as a model system

A spiro orthoester having an ester moiety, 2-acetoxymethyl-1,4,6-trioxaspiro[4.6]undecane (4) was synthesized, and its cationic polymerization and depolymerization of the obtained polymer (5) were carried out. The monomer 4 underwent cationic polymerization with a cationic catalyst to afford the corresponding poly(cyclic orthoester) 5. The obtained polymer 5 could be depolymerized with a cationic catalyst to regenerate the monomer 4 in an excellent yield. Further, bifunctional spiro orthoesters (6, 8, 9) having diester moieties were synthesized from terephthalic acid, succinic acid, and 1,4-cyclohexanedicarboxylic acid, and their acid-catalyzed reversible crosslinking–decrosslinking was examined. The bifunctional monomer 6 derived from terephthalic acid underwent cationic crosslinking to afford the corresponding network polymer (7), which could be also depolymerized to regenerate the original bifunctional monomer 6. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2551–2558, 1999