Synthesis and characterization of polythiophene block copolymer and fullerene derivative capable of “three‐point” complementary hydrogen bonding interactions and their application in bulk‐heterojunction solar cells

We report the synthesis and characterization of a polythiophene block copolymer (P4) selectively functionalized with diaminopyrimidine moieties and a thymine tethered fullerene derivative (F1). Self‐assembly between P4 and F1 through “three‐point” complementary hydrogen bonding is studied by ¹H NMR spectroscopy and differential scanning calorimetry. A large Stern‐Volmer constant (K_SV) of 1.2 × 10⁵ M^?1 is observed from fluorescence quenching experiments, revealing strong complexation between these two components. Solar cells employing P4 and F1 at different weight ratios as active layers are fabricated and tested; corresponding thin film morphologies are studied in detail by optical imaging and atomic force microscopy. Correlations between polymer complex structures, film morphologies, and device performance are discussed. Thermal stability of benchmark poly(3‐hexylthiophene) bulk heterojunction solar cells is found to be improved by the addition of a few weight percent of P4/F1 complexes as compatibilizers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3339–3350     

Association and Shape of Molecules Using Free Length Theory

Abstract

Traditionally workers engaged in calculation of the ultrasonic velocity in liquid mixtures using Jacobson's Free Length Theory (FLT) arrive at the conclusion that the predictions of FLT produce large deviations when compared with experimental velocities. Such workers seemed to have ignored the necessity of incorporating two parameters in FLT as originally suggested by Jacobson himself: one, to account for the association, and the other, for the shape of the component molecules in the mixture. By introducing the association factor and deriving explicit expressions for different shapes of the molecules, the present work has demonstrated that FLT might be made to predict ultrasonic velocities in the mixtures better. Also this approach can very well be used to account for molecular associations and shapes.     

Stereoselective photoinduced electrocyclic ring closure of aromatic enehydrazides. Asymmetric synthesis of 3-aryl dihydroisoquinolones and tetrahydroisoquinolines

A flexible route for the stereoselective synthesis of a variety of 3-aryl dihydroisoquinolones and tetrahydroisoquinolines has been developed. The key step is a diastereoselective photoinduced 6π-electrocyclic ring closure of enantiopure aromatic enehydrazides via a 1,4-remote asymmetric induction. N–N bond cleavage to release the chiral appendage from the preliminary annulated compounds and/or concomitant reduction of the lactam carbonyl group completed the synthesis of the title compounds.     

Preparation of Chiral Amino Esters by Asymmetric Phase‐Transfer Catalyzed Alkylations of Schiff Bases in a Ball Mill

The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase‐transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified.