Syntheses and Properties of Unsymmetrically Substituted Bi- and Quaterthiophenes

Abstract

The unsymmetrically substituted bi- and quaterthiophene derivatives were synthesized. The unsymmetrically substituted bithiophenes carrying the electron-withdrawing substituent X on one of the outer thiophene rings exhibited the maxima of absorption bands at the longer wavelengths than the symmetrically disubstituted bithiophene derivatives, while the unsymmetrical quaterthiophenes had such maxima at the shorter wavelengths than the corresponding symmetrical ones. The trend of bathochromic shift of the longest wavelength absorption bands due to the electron-withdrawing substituent X was more pronounced in case of bi- or quaterthiophenes bearing push–pull substituents. The unsymmetrical quaterthiophenes exhibited the greater third-order nonlinear optical (TNLO) properties than the corresponding bithiophenes, similarly to the case between the symmetrical bi- and quaterthiophenes. However, the TNLO properties of the unsymmetrical bi- and quaterthiophenes showed no dependence on the electron-withdrawing strength of the substituent X, unlike those of the symmetrical ones.

Syntheses and electronic properties of the nickel and palladium complexes of the octaethylporphyrin(M1)–(dihexylbithiophene) n –octaethylporphyrin(M2) system [OEP(M1)–(DHBTh) n –OEP(M2)] connected with the diacetylene linkage. A methodology for molecular design of the particular electronic structure

“…One dimensionally extended OEP(M) -(DHBTh) n -OEP(M) derivatives (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) also bring about some finding for the present peculiar system. As derived from the previous study, 11 it is further confirmed that the Pd complexes as well as the Ni ones show the unique spectral features with simple regularity.…”

“…Thus, it is shown that all the compounds 8 -25 in both HH and TT series possess the ring currents of OEP(M) almost the same as those for 36 and 37, regardless of the number of DHBTh, exhibiting meso-H at around 9.4 ppm for the Ni complexes and 9.9 -10 ppm for the Pd complexes (Table 1). This result exactly indicates that all the DHBTh constituents in [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] have no abilities to perturb the ring current of OEP(M), similarly to the case for 1 -7. Such a structural property indicates that the area of influence from the anisotropic effect of OEP(M) could be estimated accurately by the chemical shift analysis of Th-H, because all the DHBTh constituent are fixed both independently and regularly with a rigid diacetylene linkage in one direction.…”

“…So far, a variety of the DHBTh derivatives have been demonstrated from the viewpoint of the structure -property relationship, regarding the orientation effect of DHBTh on the conformational planarity of the molecule as a controller tool for the material function. 4,7,8,10,11 In short, the HH(DHBTh) constituent interrupts the p-electronic conjugation by increasing the dihedral angle (DA) 6 between the two HTh rings of DHBTh, in contrast with the TT(DHBTh) constituent with a fairly planar conformation convenient for transmission of the p-electronic conjugation throughout the molecule. Thus, in case of the HH series, it may be as well to explain that the electronic structures gradually separate into the two main characteristic features with increases of n; one arises from the OEP(M) -HTh component like 54 and 55, another arises from the remaining HTh-HH(DHBTh) n22 -HTh component, resulting in their combined broad spectra (Fig.…”

“…The residue obtained after removal of the solvent was chromatographed on Al 2 O 3 (3.2£20 cm) with hexane to afford 40 (135 mg, 20%) and 30 17 (297 mg) successively, together with recovery of 39 (27 mg). 40: Yellow oil; Mass (EI) m/z 456 (M þ þ1) for C 27 H 38 S 2 Si, MW¼454.8; 1 H NMR (400 MHz) d¼7.12 (1H, s, Th-H), 7.10 (1H, s, Th-H), 3.38 (1H, s, CuCH), 2.45 (4H, br t, J¼8 Hz, CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 ), 1.6-1.1 (8H, m, CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 ), 0.9 -0.7 (6H, br t, J¼6 Hz, CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 ), 0 3,7,8,12,13,17,-5-yl]-1,3-butadiynyl}-3,3 0 -dihexyl-2,2 0 -bithiophene (41) (Route A). To a solution of Cu(OAc) 2 (1.0 g, 5.5 mmol) in Py (36 cm 3 ) was added the solution of 29 (83 mg, 0.13 mmol) and 40 (258 mg, 0.57 mmol) in Py (200 cm 3 ) at 40 8C for 1 d. Stirred for additional 5 h, the reaction mixture was poured into water and extracted with CHCl 3 .…”

“…7 In particular, from the studies of the donor -acceptor DHBTh derivatives was exhibited experimentally a structure -property relationship of the higher third-order nonlinear optical (NLO) behavior with the more conjugation planarities, though qualitatively. 8 Very recently, in connection with a wide-ranging utility of the least-bulky, rigid and straight linkage of acetylene, 9 an extended p-electronic conjugation system of the DHBTh derivatives 1 and 3 combined with the nickel (Ni) complex of octaethylporphyrin [OEP(Ni)] has been synthesized to figure out the feature as a function unit for optoelectronic devices, 10 in which all the chromophores are connected with 1,3-butadiyne (diacetylene) (Chart 1). In the OEP(Ni) -DHBTh -OEP(Ni) system, these DHBTh isomers including the HT isomer 2 were also found to afford the characteristic absorption spectra of the OEP nuclei in a region of 400-500 nm, but to split their Soret bands regularly into two main bands in response to the respective orientations of DHBTh.…”