Toshinobu Ohno

Design of Fullerene Derivatives for Stabilizing LUMO Energy using Donor Groups Placed in Spatial Proximity to the C60 Cage

A series of arylated dihydrofullerene derivatives were synthesized to elucidate the effective design of fullerene derivatives for enhancing the performance of organic photovoltaics. The LUMO energy of the fullerenes was estimated by the first reduction potential and theoretical calculations. The results showed that the methoxy groups substituted at spatial proximity to the fullerene core offered significant stabilization of the LUMO level. The stabilizing effect of the directly arylated fullerenes is more significant than that of conventional methanofullerenes. The theoretical investigation was performed with regard to the electronic interaction between the methoxy and fullerene moieties.

Electroreductive silylation of activated olefins using a reactive metal anode

Abstract Electroreductive acylation of 3-aryl substituted α,β-unsaturated esters and nitriles in the presence of aliphatic carboxylic anhydrides using areactive metal anode (Mg, Al, Zn) in an undivided cell afforded the corresponding β-acyl compounds in moderate to good yields. It was found that anionic species formed by electron transfer from a cathode may be stabilized by metal ions freshly formed from an anode and undergo electrophilic attack of carboxylic anhydrides to give the β-acyl products in high yields as compared with the previously reported method using a divided cell.

Facile synthesis of silyl enol ethers by Mg-promoted coupling of aliphatic carbonyl compounds with trimethylsilyl chloride

Abstract Treatment of aliphatic carbonyl compounds with trimethylsilyl chloride with Mg turning for Grignard reaction without any pre-treatment in N,N-dimethylformamide at room temperature brought about highly facile, effective and stereoselective coupling to give the corresponding silyl enol ethers in good yields.

Electroreductive acylation of activated olefins using a reactive metal anode

Abstract Electroreductive acylation of 3-aryl substituted α,β-unsaturated esters and nitriles in the presence of aliphatic carboxylic anhydrides using areactive metal anode (Mg, Al, Zn) in an undivided cell afforded the corresponding β-acyl compounds in moderate to good yields. It was found that anionic species formed by electron transfer from a cathode may be stabilized by metal ions freshly formed from an anode and undergo electrophilic attack of carboxylic anhydrides to give the β-acyl products in high yields as compared with the previously reported method using a divided cell.

Synthesis of 1,2-disubstituted benzenes and biphenyls from phthalic acids through electroreduction followed by electrocyclic reaction with alkynes

Abstract Various substituted 1,2-dihydrophthalic acids were synthesized by electroreduction of phthalic acids in excellent yields. The electrocyclic reaction of 1,2- dihydrophthalic acids or the methyl ester with alkynes gave 1,2-disubstituted benzenes and biphenyls in good yields together with fumaric acid or methyl fumarate.

Catalysis of cyclopropenylidene palladium (II) complexes for the isomerization of quadricyclane to norbornadiene

Abstract New palladium complexes of cyclopropenylidenes of the type of trans-Cl2Pd(CP)(Py-X) have been synthesized, where CP is di-t-butylcyclopropenylidene or bis(diisopropylamino)cyclopropenylidene, and Py-X is 4-substituted pyridines (X = H, CH3, CN). The complexes revealed high catalytic activity toward the cycloreversion of quadricyclane (Q) to norbornadiene (NBD). Based on a detailed kinetic study, it is concluded that liberation of Py-X is prerequisite for the metal to interact with Q, The rate of the reaction obeys a rate expression d[NBD]/dt = kcat[cat] 1 2 [Q]. The apparent catalytic activity (kcat) can be related to the catalytic activity (k*) of the coordinatively unsaturated species Cl2Pd(CP) and the dissociation constant (K) for pyndine liberation by kcat= k*K 1 2 . The values k* and K are discussed in relation to the nature of ligands.

Controlling the Polarity of Fullerene Derivatives to Optimize Nanomorphology in Blend Films

Developing a design strategy to establish the compatibility of acceptor materials with donor materials is important for the rational development of organic solar cells. We synthesized 2,6-dimethoxyphenyl methanofullerene derivatives to realize an enhanced open-circuit voltage, and we investigated polarities and their effects on the film morphology of the active layer. The polarities of the synthesized fullerene derivatives were affected significantly by the presence of functional groups, such as methoxy, ether, and ester groups. Macro/nanoscopic morphological investigation and spectroscopic analysis of the blend films of the poly(3-hexylthiophene)(P3HT)/fullerene derivatives showed that a balanced polarity between materials results in the formation of optimized nanomorphology without grains and robust phase separation. Measurements of the device performance of the photovoltaic cells composed of P3HT and the fullerene derivatives confirmed the same tendency as that shown in the morphological analysis. This finding enables us to obtain an improved power conversion efficiency because of the enhanced open circuit voltage derived from the fullerene derivatives.

Synthesis of thienyl analogues of PCBM and investigation of morphology of mixtures in P3HT

Summary Novel [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) analogues containing benzo[b]thiophene (3a, 3b) and thieno[3,2-b]thiophene (3c, 3d) were synthesized and characterized. The morphology of the thin films prepared from the mixtures of these methanofullerenes with regioregular poly(3-hexylthiophene) (P3HT) was investigated by AFM measurement and UV-Vis absorption spectroscopy. A solubility test of these methanofullerenes was performed by using dichloromethane as a solvent. es-TThCBM (3d) exhibited 1.4 times greater solubility in dichloromethane than PCBM.

Cobalt(II) tetraphenylporphyrin-catalyzed isomerization of electronegative substituted quadricyclanes

Abstract Co(II)TPP 1 - catalysed isomerization of a series of electronegative substituted quadricyclanes( 1 ) to the corresponding norbornadiene( 2 ) was found to proceed via radicophilic attack of the metal to 1 .

Co(II)porphyrin catalyzed isomerization of bicyclobutanecarbonitrile

Abstract In the presence of catalytic amount of TPPCo(II), bicyclobutane-1-carbonitrile easily isomerized to cyclobutene-1-carbonitrile in 60–70 % yield. Reaction behavior of other electronegative substituted bicyclobutanes in the presence of TPPCo(II) was also investigated.