Synthesis, characterization and properties of coordination- and low band gap polymers for potential catalytic and photovoltaic applications

Organic/Inorganic Polymeric Materials. Four three dimensional-coordination polymers built of lanthanide ions and 2,5-TDC2- linkers along with five isostructural two-dimensional lanthanide-based coordination polymers with F4BDC linkers have been synthesized. The coordination polymers were characterized by single-crystal and powder X-ray diffraction. For Compounds 1-4, the Ln3+ metal ions are eight-coordinate, linked to other Ln3+ metal ions by six 2,5-TDC2- units and varying amounts of coordinating solvent molecules. The metal ions form a distorted sinusoidal chain which is bridged to other chains through 2,5-TDC2- linkers to form a 3D framework. The solvent molecules occupy the rhombic channels of the frameworks. For compounds 5-9, the Ln3+ metal ions are linked to an adjacent Ln3+ metal ions through the oxygen atoms of two bridging &mgr;2-F4BDC 2- ligands and two &mgr;3-F4BDC 2- bridging ligands to form a Ln2O18 dimer. The Ln2O18 dimers are linked to each-other through four F4BDC2- ligands to form 2D sheets. Compounds 1-9 were further characterized using thermogravimetric analysis and infrared spectroscopy. Studies of the photoluminescence properties of compounds 3, 5 and 7 as well as the catalytic activity of compounds 1, 7, 8 and 9 in the Biginelli reaction, are presented.;Organic Polymeric Materials. Through subtle manipulation of a solubilizing side chains on the backbone of 4,8-dialkoxybenzo[1,2- b:4,5-b']dithiophene (BDT)/2,1,3-benzothiadiazole (BT) copolymers, the molecular weight and the solution processability of the polymers can be dramatically improved. When 2-ethylhexyl side chains are attached to the 4- and 8-positions of the BDT unit, a chloroform-soluble copolymer fraction with a weight-average molecular weight (Mw) of 3.4 kg/mol is obtained (P2). By moving the ethyl branch from the 2- to the 1- position on the hexyl chain, we obtain a chloroform soluble fraction with an Mw of 68.8 kg/mol (P3). As a result of this side chain alteration, the shape of the absorption profile is dramatically altered, lambdamax is shifted from 575 to 637 nm, the hole mobility as determined by thin film transistor (TFT) measurements is improved from 9 x 10-7 to 7 x 10-4 cm2/Vs, and the solar cell power conversion efficiency (PCE) of the bulk heterojunction (BHJ) device is enhanced from 0.31 % to 2.91 %.;By further increasing the branch on the BDT backbone from a six carbon branched chain to an eleven carbon branched chain (P7-P11), soluble high molecular weight copolymers were achieved. Varying the co-monomer from 2,1,3-benzothiadiazole, to other electron withdrawing monomers (P8-P10), allowed us to lower the band gap and achieve decent efficiencies. High efficiency organic photovoltaic (OPV) devices comprised of P11 and phenyl-C71-butyric acid methyl ester (PC71BM) were fabricated by additive processing with 1-chloronapthalene (CN). When the active layer is cast from pristine chlorobenzene, the average PCE is 1.41 %. Our best condition, using 2 % chloronapthalene as a solvent additive in chlorobenzene, results in an average PCE of 5.65 %, with a champion efficiency of 6.05 %.;The donor monomer was varied from BDT to another donor monomer with a lower band gap (cyclopentadithophene, CPDT) and compared to a known BDT-based copolymer (P12) using the same thienopyrroledione acceptor monomer (P13). The polymer showed excellent solubility at room temperature in chlorinated solvents. The absorption onset for P1 is close to 740 nm as compared with ∼685 nm for PBDTTPD, corresponding to an optical band gap of 1.67 eV, which is 0.15 eV lower than PBDTTPD. The photovoltaic characteristics of the polymer were determined under AM 1.5g illumination. The P13:PCBM BHJ device showed a high Voc (0.92 V) and Jsc (8.02 mA/cm2) as well as a good PCE (2.43 %), while the best device with 2% solvent additive gave a PCE of 3.47 %.