Steric Hindrance Ligand Strategy to Aluminum Porphyrin Catalyst for Completely Alternative Copolymerization of CO_2 and Propylene Oxide

Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide（PO）, but they suffer from relatively poor poly（propylene carbonate）（PPC） selectivity. Herein, steric hindrance porphyrin ligand was used to enhance the PPC selectivity. Typically, a bulky anthracene-like group was incorporated into the porphyrin ring to form 5,10,15,20-tetra（1,2,3,4,5,6,7,8-octahydro-1,4：5,8-dimethanoanthracen-9-yl）porphyrin, the aluminum porphyrin complex with this ligand, in combination with bis（triphenylphosphine）iminium chloride as a co-catalyst, produced completely alternate PPC. Additionally, the obtained PPC showed high regioselectivity, with a head-to-tail linkage content（HT） of 92%. Therefore, we demonstrated that introduction of bulky steric ligand into the porphyrin ring could reduce the propylene oxide homopolymerization activity leading to excellent PPC selectivity, and improve regioselectivity for the PO ring-opening during the copolymerization.

SYNTHESIS, CHARACTERIZATION AND SOLAR CELL APPLICATION OF A D-A COPOLYMER WITH CYCLOPENTADITHIOPHENE AND FLUORENE AS DONOR UNITS

In this paper, a new D-A copolymer, PFDBCPDT, which consists of benzo-2,1,3-thiadiazole as acceptor units and cyclopentadithiophene and fluorene as donor units, was synthesized. The thermal, electrochemical, photophysical and photovoltaic properties of PFDBCPDT were studied. PFDBCPDT showed a low optical band gap of 1.84 eV, and relatively low HOMO level of-5.69 eV. The best device performance was obtained by PFDBCPDT/PC61BM （1：3） with 0.5 vol% DIO. The device exhibited a power conversion efficiency of 3.06%, with a relatively high open circuit voltage of 0.87 eV.

Acceptor-Donor-Acceptor Conjugated Oligomers Based on Diketopyrrolopyrrole and Thienoacenes with Four, Five and Six Rings for Organic Thin-film Transistors

Three acceptor-donor-acceptor （A-D-A） conjugated oligomers, i.e., O1, 02 and 03, have been synthesized using diketopyrrolopyrrole （DPP） as an electron-acceptor unit, and naphtho[1,2-b：5,6-b＇]dithiophene （NDT）, anthra[1,2-b：5,6- b＇]dithiophene （ADT） or dithieno[3,2-b：Y,2＇-b＇]naphtbo[1,2-b：5,6-b＇]dithiophene （DTNDT） as electron-donor unit. These oligomers exhibit identical highest occupied molecular orbital （HOMO） and lowest unoccupied molecular orbital （LUMO） energy levels, which were ca. -5.1 and -3.3 eV, respectively. Upon thermal annealing, all three oligomers formed thin films with ordered microstructures, and their organic thin film transistors （OTFTs） exhibited p-type transport behavior. The mobility was increased with an extension of the size of D-units. 03 showed the best OTFT performance with the mobility of up to 0.20 cm2·V-1 ·s-1. The film quality of 03 was improved by adding 1 wt% poly（methylmethacrylate） （PMMA）. In consequence, the mobility of the O3-based devices was further enhanced to 0.30 cm2·V-1 ·s-1.