π-Conjugated and Light Emitting Poly(4,4‘-dialkyl-2,2‘-bithiazole-5,5‘-diyl)s and Their Analogues Comprised of Electron-Accepting Five-Membered Rings. Preparation, Regioregular Structure, Face-to-Face Stacking, and Electrochemical and Optical Properties

Abstract

Poly(4,4‘-dialkyl-2,2‘-bithiazole-5,5‘-diyl)s (PRBTz, alkyl = methyl (PMeBTz), butyl (PBuBTz), and heptyl (PHepBTz)) and their analogues comprised of 33−150 thiazole rings have been prepared by organometallic polycondensation, and their chemical and physical properties are compared with those of π-conjugated poly(thiophene-2,5-diyl) (PTh) and poly(pyridine-2,5-diyl) (PPy). Electrochemical n-doping of PRBTz takes place at E° = −1.77 to −2.30 V vs Ag/Ag+ and is accompanied by the appearance of a new absorption band in the near-infrared. PMeBTz assumes a relatively stiff structure in solution and shows a large refractive index increment of 0.55 cm3 g-1; powder X-ray diffraction analysis of PMeBTz supports a face-to-face type stacking of the polymer chains in the solid state. All of the polymers show photoluminescence in solutions and in the solid, and an electroluminescence device using PMeBTz as the emitting layer gives emission of light at λmax = 680 nm with 100 cd m-2 at 8 V. A thin film of PMeBTz gives an optical third-order nonlinear susceptibility χ(3) of 2.5 × 10-11 esu, which is larger than observed with PTh and PPy films, and comparison of the χ(3) value with that (0.3 × 10-11 esu) of nonregioregular poly(4-methylthiazole-2,5-diyl) (PMeTz) reveals the importance of the regioregular structure of PMeBTz to give the larger χ(3) value.

Comparison of Packing Modes of Poly(thiophene)s and Poly(thiazole)s

“…To the reaction mixture was added Me 3 SnCl, and stirring at -50°C for 1 h followed by distillation (66-67°Cj 1. 5 HH-PTz was prepared analogously by using 5,5'-bis-(trimethylstannyl)-2,2'-bithiazole (Me 3 Sn-Tz-Tz-SnMe 3 ) and 5,5'-dibromo-2,2'-bithiazole (Br-Tz-Tz-Br) (eq 2). Me 3 Sn-Tz-Tz-SnMe 3 was prepared according to the literature.…”

Self-assembly of rod-coil block copolymers from weakly to moderately segregated regimes

“…The rod-coil block copolymer case is by far more complex, as liquid crystalline behaviour is induced by the presence of a rigid block in the block copolymer backbone, which can compete with or even dominate the classical microseparation arising from the positive enthalpy of mixing of the two different blocks. Further degrees of complexity in self-assembly of rod-coil block copolymer systems arise from intermolecular forces frequently occurring among rod-like polymers: in the cases of rod polymers realized by alpha-helices secondary structures in polypeptides, H-bonding can arise in between contiguous rods; similarly, in π-conjugated polymer rods, π-π interactions may form among closely packed rods [16][17][18]. Both types of intermolecular forces are expected to greatly affect the phase separation mechanisms.…”

Acceleration Effect of a π-Conjugated Polymer-Modified Electrode for Electrolytic Evolution of H2 in H2SO4(aq)

“…9 P4HepBTz was soluble in organic solvents, and painting a platinum plate (φ = 6.1 mm) with a trifluotoacetic acid solution of P4HepBTz and drying up under vacuum gave a smooth thin film on the platinum plate, which was purchased from Tokuriki Co, Ltd. Pt and washed with concd HNO 3 , formic acid, acetone, and hexane in this order in an ultrasonic cleaner. Figure 1 exhibits a sketch of the cell constructed with the P4HepBTz-modified platinum electrode.…”

“…8 However, they could not observe the acceleration effect, either. We now report that a recently prepared π-conjugated polymer, poly(4,4 -diheptyl-2,2 -bithiazole-5,5 -diyl), P4HepBTz, 9 gives such an acceleration effect for cathodic evolution of H 2 in 0.5 M H 2 SO 4 . P4HepBTz is one of typical n-type conducting polymers, and susceptible to electrochemical reduction to generate negative carriers in its film by † To whom correspondence should be addressed.…”