Pyridine polymer-based

Shinkai (65) exploited the boronic acid-diol motif mentioned above to self-assemble a polymer based on pyridine-magnesium porphyrin interactions. In this case, the evidence for polymerization comes from lightscattering experiments in dilute solution which yielded an average molecular weight of 109 g mol-1 for this system. 

Kureshy developed a polymer-based chiral Mn-salen complex (Figure 21). Copolymerization of styrene, divinylbenzene, and 4-vinylpyridine generated highly cross-linked (50%) porous beads loaded with pyridine ligands at 3.8 mmol g-1. Once the polymer was charged with the metal complex catalyst, enantioselective epoxidation of styrene derivatives was achieved with ee values in the range 16 46%. 79... 

The search for new coordination SCO polymers based on the assembling of iron(II) and bridging molecules other than 1,2,4-triazole- or l-i -tetrazole-based ligands has afforded a series of frameworks closely related to the 2D system [Fe(btr)2(NCX)2]-H20 (X=S, Se). This series of compounds formulated as [FeL2(NCS)2]-nSolv can be considered as derived from the formal substitution of btr by bis-monodentate pyridine-like ligands such as bispyridylethylene (bpe, n=l, Solv=MeOH), fraus-4,4 -azopyridine (azpy,... 

The preparation of polyamines directly from a monomer like pyridine has commercial interest because the resulting polymer would be a base resin with a potentially high capacity. Universal Oil has patented the process by which a polypyridine was made.41 Possible structures for pyridine polymers were proposed.42 The influence of Be2+ and Mg2+ was also studied.43... 

In addition, taper-shaped and dendritic units were connected either covalently (at the apex or at the periphery) [133,135, 383,405] or by means of self assembly (e.g., hydrogen bonding [399]) to a polymer backbone. For example, polymers based on poly[4-(3-methacryloylpropyl]pyridine] form hydrogen bonded complexes with partially fluorinated mono-, di-, or trisubstituted benzoic acids (see complex 221 in Fig. 72). The type of mesophase formed by these complexes varies from smectic via columnar to cubic, most probably micellar cubic, with rising... 

As with all supramolecular structures, one of the most important issues is whether a direct relationship between the structure of a material and its function or properties can be established. In the following, some examples of polymer systems which show such a correlation will be discussed. The materials addressed will include block copolymers, polyalkylthiophenes and a multilayer system based on the self-assembly of polyelectrolytes. Detailed studies on the electrochemical properties of redox-active polymers, based on poly(vinyl pyridine) modified with pendent osmium polypyridyl moieties, have shown that electrochemical, neutron reflectivity and electrochemical quartz crystal microbalance measurements can yield detailed information about the structural aspects of thin layers of these materials. 

In this area, recent unrelated efforts of the groups of Bhattacharya and Fife toward the development of new aggregate and polymer-based DAAP catalysts deserve mention. Bhattacharya and Snehalatha [22] report the micellar catalysis in mixtures of cetyl trimethyl ammonium bromide (CTAB) with synthetic anionic, cationic, nonionic, and zwitterionic 4,4 -(dialkylamino)pyridine functional surfactant systems, lb-c and 2a-b. Mixed micelles of these functional surfactants in CTAB effectively catalyze cleavage of various alkanoate and phosphotriester substrates. Interestingly these catalysts also conform to the Michaelis-Menten model often used to characterize the efficiency of natural enzymes. These systems also demonstrate superior catalytic activity as compared to the ones previously developed by Katritzky and co-workers (3 and 4). 

The synthetic route to acridine-containing polymers is outlined in Scheme I. 9-Methyl acridine (II) was prepared via 9-ethyl-malonate acridine by the method of Campbell et al (14), from 9-chloroacridine (I, Kodak), (mp. 117-8°C from ligroin). 9-(3hydro-xyethyl) acridine (III) was synthesized via the condensation of formaldehyde with II (15) (mp. 154-6°C, from ethanol-water). Metha-cryloylchloride, freshly distilled, was reacted with III in dry THF with pyridine as base to give IV, 2-(9-acridyl) ethylmethacrylate, purified by chromatography with silica gel/toluene to give red gum (IR 5.85 ym ester carbonyl stretch). 

Utilization of the single hydrogen bond between pyridine and benzoic acids in SLCP s has been a source of inspiration for other groups in the development of main-chain supramolecular polymers based on diacids and dipyridines.53-56 Supramolecular rod-coil polymers have been developed by assembly of 4,4 -bipyridines and telechelic polypropylene oxide with benzoic acid end-groups, which show highly ordered liquid crystalline phases.57 The use of tartaric acid derivatives in combination with bipyridine units resulted in the formation of hydrogen-bonded, chiral main-chain LCP s, as has been shown by circular dichroism measurements, optical microscopy, and X-ray data.58,59... 

Many amine-hydrofluoric acid reagents still have sufficient acidity to add to carbon-carbon double and triple bonds to yield hydrofluorination products. Olah s Reagent (70% HF-pyridine) [55] and its polymer-based analog [56] are especially widely used as less hazardous alternatives to anhydrous hydrofluoric acid. By selection of the right co-solvent it is even possible to modulate the reactivity of 70 % HF-pyridine so that highly selective, partial hydrofluorination of systems with several double bonds becomes feasible [61] (Scheme 2.21). 

The same reaction was studied with soluble polymer 38, prepared by polymerization of 4-(N,N-diallylamino)pyridine. This catalyst was even more efficient than 37 or 4-(pyrrolidino)pyridine, a base with much higher activity than DMAP [177]. 

Table 7.3 Imprinted Polymer-Based Solid-Phase Extraction Abbreviations AA acrylamide MAA methacrylic acid VPy vinyl pyridine ...

Similar to the biguanide structures, Dizman et al. created l,4-diazabicyclo[2.2.2]octane (DABCO)-based stmctures carrying two quaternary ammonium charges with butyl and hexyl alkyl extensions (C12). The monomer was assembled by multiple nucleophilic substitution reactions. Polymers were formed by free radical polymerization in water. These polymers, much like the biguanide acrylate and pyridinium polymers, combined hydrophobidty and cationic charge on the same monomer. One difference is that the cationic charge was also separated from the backbone of the polymer by a long alkyl chain. As with the pyridine polymers, the hexyl alkyl monomers were found to be the most effective biocides. 

Stenger-Smith, J. D., Lai, W. W., Irvin, D. J., Yandek, G. R., and Irvin, J. A (2012). Electroactive polymer-based electrochemical capacitors using poly(benzimidazo-benzophenanthroline) and its pyridine derivative poly(4-aza-benzimidazo-benzophenanthroline) as cathode materials with ionic liquid electrol Ae, / Power Sources, 220, pp. 236-242. 

Lu, H.-F., H.S.O. Chan, and S.C. Ng. 2003. Synthesis, characterization, and electronic and optical properties of donor-acceptor conjugated polymers based on alternating bis(3-alkylthiophene) and pyridine moieties. Macromolecules 36 (5) 1543—1552. 

Du Bois, C.J., et al. 2001. Multi-colored electrochromic polymers based on BEDOT-pyridines. Synth Met 119 321. 

Maruska et al. described the separations of polar aromatic solutes such as pyridine, 4-pyridylmethanol, 4-methoxyphenol, 2-naphthol, catechol, hydroqui-none, resorcinol, and 2,7-dihydroxynaphthalene by normal-phase micro-HPLC on acrylic polymer-based continuous beds as illustrated in Figure 8. Efficiencies of up to 150000 plates per meter were achieved on columns II and III, which only differ by their monomer composition. 

---