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.

Two [2]rotaxanes have been assembled in water from modular subunits through CuI‐catalyzed azide–alkyne “click” chemistry. For this purpose, 2,6‐disubstituted naphthalene axles with solubilizing oligo(ethylene glycol) (OEG) chains (n = 1–5) and propargyl terminal groups were synthesized and examined for their propensity to form inclusion complexes with a dicationic Diederich‐type cyclophane host. The dependence of pseudorotaxane formation on the linkers between the naphthalene core and OEG chains, and in the case of ester linkers on different spacer lengths, was analyzed by titration experiments. In addition, the inclusion complexes of two [2]rotaxanes were trapped by using a water‐soluble azide‐functionalized stopper. Repetitive chromatography finally enabled the isolation of both mechanically interlocked [2]rotaxanes.

The incorporation of a linear D-π-A “push-pull” chromophore synthesized by a Knoevenagel condensation as axle of a rotaxane is reported. While the introduction of the mechanical stoppers by the reversible...

We present the concept of electrostatic field driven supramolecular translation within electrically connected plasmonic nano-antennas. The antenna serves as anchoring point for the mechanically interlocked molecules, as electrode for the electrostatic field, and as amplifier of the antenna-enhanced fluorescence. The synthesis of a push-pull donor-π-acceptor chromophore with optical properties aligned to the antenna resonance is described and its immobilization on the surface demonstrated. Photoluminescence experiments of the chromophore on a gold nanoantenna are shown, highlighting the molecule-antenna coupling and resulting emission intensity increase. The successful synthesis of an electrostatic field sensitive [2]rotaxane in water is described and the tightrope walk between functionality and water solubility is illustrated by unsuccessful designs. In solution, enhanced fluorescence quantum yield is observed for the chromophore comprised in the mechanically interlocked [2]rotaxane in water and DMSO compared to the reference rod, ideal for future experiments in plasmonic nano-antennas.

The synthesis of two water‐soluble oligophenylene‐ethynylene (OPE)‐rods with substituted iso‐ and terephthalate end groups is presented. Both undergo slow association with a Diederich‐type cyclophane in aqueous solution. Formation of [2]pseudorotaxanes occurs with reaction half‐lives of several hours. Characterization of the supermolecules by 1H‐NMR spectroscopy reveals a high thermodynamic stability and kinetic inertness of the pseudorotaxanes. The phthalate precursors are functionalized with peripheral azide groups, which make them modular precursors for construction of mechanically interlocked molecules in water.