Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo[1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of −5.38 and −5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10−8 cm2 V−1 s−1 in PBDF to 1.0 × 10−5 cm2 V−1 s−1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm−2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

A tandem directed metalation has been successfully applied to the preparation of thieno[2,3-f]benzofuran-4,8-dione, providing an efficient and facile approach to symmetrically and unsymmetrically functionalize the thieno[2,3-f]benzofuran core at the 2,6 positions as well as to introduce the electron-withdrawing or -donating groups (EWG or EDG) at its 4,8 positions. The presence of various functional groups makes late-stage derivatization attainable.

Heteroatom substitution into the cores of alternant, aromatich ydrocarbons containing only even-membered rings is attracting increasing interesta samethod of tuning their electrical conductance.H ere, the effect of heteroatom substitution into molecular cores of non-alternant hydrocarbons, containing odd-membered rings,i se xamined. Benzodichalcogenophene (BDC) compounds are rigid, planar p-conjugated structures,w ith molecular cores containing five-membered rings fused to as ix-membered aryl ring. To probe the sensitivity or resilience of constructive quantumi nterference (CQI) in these non-bipartite molecular cores,t wo C 2 -symmetric molecules (I and II) and one asymmetric molecule (III) were investigated. I( II) contains S( O) heteroatoms in each of the five-membered rings, while III containsa nSin one five-membered ring anda nOin the other.D ifferences in their conductances arise primarily from the longerS ÀCa nd shorterO ÀCb ond lengths compared with the CÀCbond and the associatedc hangesint heir resonancei ntegrals. Although the conductanceo fI II is significantlyl ower than the conductances of the others, CQI was found to be resilientand persist in all molecules.[a] Dr.

The synthesis and characterization of zwitterionic molecular [c2]- and [a2]-daisy chains are described, relying on recognition of a positively charged cyclophane and a negatively charged oligo(phenylene-ethynylene) (OPE) rod in aqueous medium. For this purpose, syntheses of an acetylene-functionalized macrocyclic receptor and a water-soluble OPE-rod as the guest component are presented, from which a heteroditopic daisy chain monomer was prepared. This monomer aggregated strongly in water/methanol 4:1 and formed molecular daisy chains, which were isolated as interlocked species from a stoppering reaction at 1 mm concentration. The cyclic dimer [c2] was the main product with an isolated yield of 30 % and consisted of a mixture of diastereomers, as evidenced by H NMR spectroscopy.