- Helical pitch of m-phenylene ethynylene foldamers by double spin labeling
-
To investigate the helical conformation of oligo(m-phenylene ethynylene)s, a pair of TEMPO spin labels were appended to the backbone. The two TEMPO radicals were separated by the four, five, and six repeating units. ESR spectra of the labeled oligomers were measured in chloroform and in ethyl acetate solvents in which the oligomers are disordered and folded, respectively. The measurement and analysis of ESR spectra revealed that six repeating units make one helical turn. Copyright
- Matsuda, Kenji,Stone, Matthew T.,Moore, Jeffrey S.
-
-
Read Online
- Synthesis of a novel dinuclear ruthenium polypyridine dye for dye-sensitized solar cells application
-
A new dinuclear ruthenium(II) polypyridine complex has been successfully synthesized. The new compound has been characterized by spectroscopic and electrochemical methods. Its potential application as a sensitizing dye in dye-sensitized solar cells has been checked under AM 1.5 G irradiation conditions (100 mW cm-2) and its performance was compared to that of a commercially available mononuclear analogous dye. The overall light-to-electricity conversion efficiency of the photovoltaic device sensitized by the new dinuclear dye has been found to be over 2.5 times lower than that sensitized by the commercial analogue, despite a much higher extinction coefficient of the former dye. The probable reasons for the lower photovoltaic activity are discussed.
- Zalas,Gierczyk,Klein,Siuzdak,P?dziński,?uczak
-
p. 381 - 387
(2013/11/06)
-
- Synthesis of new dendritic antenna-like polypyridine ligands
-
An efficient synthesis of multidentate polypyridine ligands, 3,5-bis(2,2′-bipyridin-4-ylethynyl)benzoic acid and 3,5-bis(2,5-bis(2- pyridyl)-pyridin-4-ylethynyl)benzoic acid, with potential application in the production of ruthenium dyes for dye-sensitised solar cells was developed. Isolation of intermediate products and final compounds is simple and the yields are very high. The ligands obtained can be used in the synthesis of dendritic analogues of well known and very efficient N3 dye and "black dye".
- Zalas, Maciej,Gierczyk, Blazej,Ceglowski, Michal,Schroeder, Grzegorz
-
p. 733 - 740
(2013/07/26)
-
- m-Diethynylbenzene macrocycles: Syntheses and self-association behavior in solution
-
m-Diethynylbenzene macrocycles (DBMs), buta-1,3-diyne-bridged [4n]metacyclophanes, have been synthesized and their self-association behaviors in solution were investigated, Cyclic tetramers, hexamers, and octamers of DBMs having exo-annular octyl, hexadecyl, and 3,6,9-trioxadecyl ester groups were prepared by intermolecular oxidative coupling of dimer units or intramolecular cyclization of the corresponding open-chain oligomers. The aggregation properties were investigated by two methods, the 1H NMR spectra and the vapor pressure osmometry (VPO). Although some discrepancies were observed between the association constants obtained from the two methods, the qualitative view was consistent with each other. The analysis of self-aggregation by VPO revealed unique aggregation behavior of DBMs in acetone and toluene, which was not elucidated by the NMR method. Namely, the association constants for infinite association are several times larger than the dimerization constant, suggesting that the aggregation is enhanced by the formation of dimers (a nucleation mechanism). In polar solvents, DBMs aggregate more strongly than in chloroform due to the solvophobic interactions between the macrocyclic framework and the solvents. Moreover, DBMs self-associate in aromatic solvents such as toluene and o-xylene more readily than in chloroform. In particular, the hexameric DBM having a large macrocyclic cavity exhibits extremely large association constants in aromatic solvents. By comparing the aggregation properties of DBMs with the corresponding acyclic oligomers, the effect of the macrocyclic structure on the aggregation propensity was clarified. Finally, it turned out that DBMs tend to aggregate more readily than the corresponding phenylacetylene macrocycles, acetylene-bridged [2n]metacyclophanes, owing to the withdrawal of the electron density from the aromatic rings by the butadiyne linkages which facilitates π-π stacking interactions.
- Tobe, Yoshito,Utsumi, Naoto,Kawabata, Kazuya,Nagano, Atsushi,Adachi, Kiyomi,Araki, Shunji,Sonoda, Motohiro,Hirose, Keiji,Naemura, Koichiro
-
p. 5350 - 5364
(2007/10/03)
-