Synthesis Of Novel Fused Thiophene-Based Materials And Study On Chirality Of Thiophene-Based Naphthalene Cored Double Helicenes

In recent years, thiophene helicene compounds due to their conjugation and chiral features in asymmetric catalysis, organic photovoltaic materials in the field have a certain prospect, has aroused more and more attention, In this article, some novel compounds have been designed and synthesized based on dithieno[2,3-b:3’,2’-d]thiophene, and these compounds are characterized specifically as follows:Part Ⅰ:chiral resolution and racemization of double helicene (11)In this section, we conducted the synthesis of double helicene (11) based on the our reported method, resolution by chiral column and the study on the formation mechanism of the enantiomer of racemic and racemization, and it was found that the double helicene racemate can be resoluted by the RC-SCDP5semipreparative column (mobile phase, hexane:isopropanol=98:2(v:v); flow rate:1.0mL/min). After chiral separation, the enantiomers were named as ypp-1-78-col-HPLC2-col1and ypp-1-78-col-HPLC2-col2, respectively characterized ypp-1-78-col-HPLC2-col1ee=84%,[a]D17=273°(c=0.07g/100mL, spectroscopically pure chloroform) and ypp-1-78-col-HPLC2-col2ee>99%,[a]D17=+505°(c=0.04625g/100mL, spectroscopically pure chloroform) and a good mirror relationship was shown up in the CD spectra of the enantiomers. Meanwhile, our group measured by the photochemical synthesis of the racemate lla and mesomer (R,S)-11a, the half-life for ypp-1-78-col-HPLC2-col2is of57.6h at232℃. However, the racemic (R,S)-11a even heated at250℃for10days without transforming to the racemic (R,R)-11a, or (S,S)-11a, through the study of mechanism of11a racemization, it was found that the double helic in the ends in double helicene could invert simultaneously when heated, rather than rollover occurs at one of the end.Part Ⅱ:synthesis and study spectroscopic behavior of D-A compounds based on dithieno[2,3-b:3’,2’-d] thiopheneIn this chapter, starting from fused dithieno[2,3-b:3’,2’-d]thiophene, compound5was obtained by NBS from dithieno[2,3-b:3’,2’-d]thiophene; after Li/Br exchange reaction, compound8was formed with the addition of N,N-dimethylformamide (DMF). The target compound12was synthesized via Knoevenagel condensation of compound8and malononitrile, and13was obtained by the Li/Br exchange of 5-bromo-2-trimethyl-silanyldithieno[2,3-b:3’,2’-d]thiophene(5) and quenched with N,N-dimethylformamide; compound14was got from13and malononitrile via the Knoevenagel condensation. With2,5-dibromodithieno[2,3-b:3’,2’-d]thiophene (6) as the starting material, compound15was obtained via the Li/Br exchange and quenching with the aldehyde of the dithieno[2,3-b:3’,2’-d]thiophene. Through the oxidization of the pyridinium chlorochromate (PCC), the final compound17was obtained. All of the compoud12,14,17was characterized by1H NMR,13C NMR, MS, HRMS and IR.In the UV-visible spectra of compounds12,14,17, each compound in solvents of different polarity in the UV absorption peak did not change significantly, the maximum absorption peak is respectively409nm,428nm and428nm, Compound12(ε:3.9×104),14(ε:3.6x104),17(ε:4.8×104) of the absorption intensity belong to π-π*transition, compound14and12exhibited similar red-shift compared with17and the similar absorption beheviors were due to cross-conjugation structures of compound14and17, which didn’t increase conjugation length1of the corresponding compound.Part III:synthesis of thiophene [7]helicene based on dithieno[2,3-6:3’,2’-d]thiopheneAiming at a new type of thiophene [7]helicene from3-bromothiophene was utilized as materials, via several steps the precursor was obtained but the target molecule was not obtained. Compound5was synthesized by NBS from dithieno[2,3-b:3’,2’-d]thiophene,then after bromine dancing reaction under LDA, compound7was obtained Via the Li/Br exchange of7and with (PhSO2)2S, compound18was obtained with a yield of40%. Following by the deprotonation with LDA for18and coupling with CuCl2, compound19was supposed to be formed, but there is no evidence for the successful formation of this compound. Compound18was characterized by1H NMR,13C NMR, MS, HRMS, and analyzed by X-ray crystallographic analysis.