Conjugated block copolymers via functionalized initiators and click chemistry

Conjugated block copolymers are potentially useful for organic electronic applications and the study of interfacial charge and energy transfer processes; yet few synthetic methods are available to prepare polymers with well‐defined conjugated blocks. Here, we report the synthesis and thin film morphology of a series of conjugated poly(3‐hexylthiophene)‐block‐poly(9,9‐dioctylfluorene) (P3HT‐b‐PF) and poly(3‐dodecylthiophene)‐block‐poly(9,9‐dioctylfluorene) (P3DDT‐b‐PF) block copolymers prepared by functional external initiators and click chemistry. Functional group control is quantified by proton nuclear magnetic resonance spectroscopy, size‐exclusion chromatography, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The thin film morphology of the resulting all‐conjugated block copolymers is analyzed by a combination of grazing‐incidence X‐ray scattering, atomic force microscopy, and transmission electron microscopy. Crystallization of the P3HT or P3DDT blocks is present in thin films for all materials studied, and P3DDT‐b‐PF films exhibit significant PF/P3DDT co‐crystallization. Processing conditions are found to impact thin film crystallinity and orientation of the π–π stacking direction of polymer crystallites. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 154–163     

tert‐Amino effect at a coumarin and a 2‐quinolone system: Synthesis of 1,2 fused 5H‐chromeno[4,3‐b]pyridin‐5‐ones and a 6H‐benzo[h][1,6]naphthyridin‐5‐one

Some novel 1,2‐fused 5H‐chromeno[4,3‐b]pyridin‐5‐ones ( 5a,b ) and a 6H‐benzo[h][1,6]naphthyridin‐5‐one ( 5c ) have been synthesized starting from the 4‐chlorocoumarin‐3‐carbaldehyde ( 1a ) or its N‐methyl‐2‐quinolone analogue ( 1b ) via subsequent Knoevenagel condensation and ring closure reaction known as the ‘tert‐amino effect’. These are rare examples of the tert‐amino effect occurring at 2‐pyrone and 2‐pyridone ring. An unusual intramolecular redox reaction of the iminium ion 6 , reported earlier, most probably follows analogous mechanism as the tert‐amino effect reactions leading to 5 .     

Homologous Silver Bismuth Chalcogenide Halides (N,x)P. II. The (2, x)P and (3, x)P Structure Families of Modular Compounds with Tunable Composition and Structure

The crystal structures of two members of the solid solution series Ag_3xBi_5?3xS_8?6xCl_6x?1 (x = 0.52 (I) , x = 0.67 (II) ) and three compounds of the Ag_4xBi_6?4xQ_10?8xBr_8x?2 series (Q = S: x = 0.70 (III) , x = 0.84 (IV) ; Q = Se: x = 0.72 (V) ) were determined by single‐crystal X‐ray diffraction. The compounds crystallize in the monoclinic space group C2/m (No. 12) with a = 1326.7(3), b = 403.9(1), c = 1176.7(2) pm, β = 107.83(3)° for (I) ; a = 1325.4(3), b = 403.3(1), c = 1170.6(2) pm, β = 108.14(3)° for (II) ; a = 1338.9(4), b = 407.7(1), c = 1426.4(4) pm, β = 113.95(2)° for (III) ; a = 1346.7(4), b = 409.3(1), c = 1440.7(4) pm, β = 114.40(1)° for (IV) ; and a = 1370.9(2), b = 417.64(4), c = 1480.4(2) pm, β = 114.92(2)° for (V) . (I) and (II) adopt the PbBi₄S₇ structure type, (III) to (V) crystallize in the CuBi₅S₈ type. All five compounds belong to the homologous series with general formula [BiQX]₂[Ag_xBi_1?xQ_2?2xX_2x?1]_N+1 (Q = S, Se; X = Cl, Br; 1/2 ≤ x ≤ 1)), which resemble minerals of the pavonite series. They are characterized by the parameters N and x and are denoted ^{(N, x)}P. In the crystal structures, two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face‐sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M = Ag/Bi) between them. Modules of type B are composed of chains of edge‐sharing [MZ₆] octahedra (M = Ag/Bi; Z = Q/X). These NaCl‐type fragments are of thickness N = 2 in Ag_3xBi_5?3xS_8?6xCl_6x?1 and N = 3 in Ag_4xBi_6?4xQ_10?8xBr_8x?2. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions and Q/X mixed occupation of some anion positions.     

Homologous Silver Bismuth Chalcogenide Halides (N,x)P. III. The (4, x)P, (5, x)P,and (7, x)P Structure Families of Modular Compounds with Tunable Composition and Structure

The crystal structures of six members of the homologous series with general formula [BiQX]₂[Ag_xBi_1?xQ_2?2xX_2x?1]_N+1 (Q = S, Se; X = Cl, Br; 1/2 ≤ x ≤ 1) and N = 4, 5, or 7 were determined by single‐crystal X‐ray diffraction. The series are characterized by the parameters N and x and are denoted ^{(N, x)}P. Ag₃Bi₄S₆Cl₃ (x = 0.60) (I) , Ag_3.5Bi_3.5S₅Br₄ (x = 0.70) (II) and Ag_3.65Bi_3.35Se_4.70Br_4.30 (x = 0.73) (III) belong to ^{(4, x})P series Ag_5xBi_7?5xQ_12?10xX_10x?3 and adopt the AgBi₆S₉ structure type. The ^{(5, x)}P compound Ag_3.66Bi_4.34S_6.68Br_3.32 (IV) , which corresponds to x = 0.61 in Ag_6xBi_8?6xS_14?12xBr_12x?4, crystallizes isostructurally to AgBi₃S₅. The compounds Ag_4.56Bi_5.44Se_8.88Br_3.12 (x = 0.57) (V) and Ag_5.14Bi_4.86S_7.76Br_4.24 (x = 0.64) (VI) , which are members of ^{(7, x)}P series Ag_8xBi_10?8xQ_18?16xBr_16x?6, adopt the Ag₃Bi₇S₁₂ structure type. In the monoclinic crystal structures (space group C2/m) two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face‐sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M = Ag/Bi) between them. Modules of type B are composed of [MZ₆] octahedra, which are arranged in NaCl‐type fragments of thickness N. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions as well as Q/X mixed occupation of some anion positions. Corresponding to their black color, all compounds are narrow‐gap semiconductors (E_g = 0.35 eV for (II) ). General characteristics of the entire class of ^{(N, x)}P compounds are gathered in a catalogue.     

Cobalt‐Catalyzed Cross‐Coupling of Functionalized Alkylzinc Reagents with (Hetero)Aryl Halides

A combination of 10 % CoCl₂ and 20 % 2,2′‐bipyridine ligands enables cross‐coupling of functionalized primary and secondary alkylzinc reagents with various (hetero)aryl halides. Couplings with 1,3‐ and 1,4‐substituted cycloalkylzinc reagents proceeded diastereoselectively leading to functionalized heterocycles with high diastereoselectivities of up to 98:2. Furthermore, alkynyl bromides react with primary and secondary alkylzinc reagents providing the alkylated alkynes.     

Synthesis and antimicrobial activity of a series of optically active quaternary ammonium salts derived from phenylalanine

We synthesized nine quaternary ammonium compounds (QUATs) starting from phenylalanine, N-alkyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromides, which were prepared as optically pure substances. Five compounds were prepared as S-enantiomers and four compounds as R-enantiomers. These compounds were evaluated by their activities against bacteria and fungi. Three microbial strains were used in the study: the gram-negative bacteria Escherichia coli, the gram-positive bacteria Staphylococcus aureus and the fungi Candida albicans. The activities were expressed as minimum bactericidal or fungicidal concentrations (MBC). The most active compounds were (2S)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide and (2R)-N-tetradecyl-N,N-dimethyl-(1-hydroxy-3-phenylpropyl)-2-ammonium bromide, with MBC values exceeding those of commercial benzalkoniumbromide (BAB) used as standard. The relationships between structure and biological activity of the tested QUATs were quantified by the bilinear model (QSAR) and are discussed.