- Photochromism of Benzylviologens Containing Methyl Groups on Pyridinium Rings and Embedded in Solid Poly(N-vinyl-2-pyrrolidone) Matrix
-
Benzylviologens with 2,2'- and 3,3'-dimethyl groups embedded in poly (N-vinyl-2-pyrrolidone) matrix indicate reversible photochromisms with absorption maxima at 605 and 775 nm under light, respectively, which are different from those (610, 570 nm) of conventional benzylviologens.
- Kamogawa, Hiroyoshi,Sugiyama, Masashi
-
-
Read Online
- Synthesis of crown-ester-bipyridines and crown-ester-viologens
-
Six novel 4,4′-bipyridine-crown-esters, derived from [4,4′]bipyridinyl-3,3′-dicarboxylic acid, [4,4′]bipyridinyl-2, 2′-dicarboxylic acid and [4,4′]bipyridinyl-2,2′,6,6′- tetra-carboxylic acid were synthesized employing a procedure closely related to the 'cesium carbonate method'. The 4,4′-bipyridine-crown-esters differ in their substitution positions of the aromatic bipyridine-units, as well as in the geometric extensions of their crown-ester moieties. Addition of 1,3-propane sultone to the 4,4′-bipyridine-crown-esters resulted in five novel propanesultonated 4,4′-bipyridine-crown-ester viologens. Georg Thieme Verlag Stuttgart.
- Bossmann, Stefan H.,Duerr, Heinz,Pokhrel, Megh Raj
-
-
Read Online
- A Molecular Switch for Control of Conformation: Strained Intramolecular Co-ordination in 4,4'-Bipyridyl-capped Zinc Porphyrins
-
Intramolecular co-ordination between the nitrogens of the cap and the central metal ion in the title compounds forces the porphyrin and bipyridyl groups to be perpendicular: addition of an external ligand releases the bipyridyl ligand which then lies parallel to the porphyrin.
- Leighton, Philip,Sanders, Jeremy K. M.
-
-
Read Online
- Synthesis of Bipyridyl-, Viologen-, and Quinone-bridged Porphyrins
-
Mesoporphyrin-II has been bridged by several 2,2'-hydroxymethyl-substituted 4,4'-bipyridine compounds.N-Methylation of the bipyridine bridge groups yielded viologen-bridged porphyrins which have unusual aggregation and fluorescence properties.An improved route to quinone-bridged porphyrins is also reported.
- Leighton, Philip,Sanders, Jeremy K. M.
-
p. 2385 - 2394
(2007/10/02)
-
- The Synthesis and Electrochemical Study of New Electrochromic Viologen-based Materials
-
A range of diquaternary salts of 4,4'-bipyridine and 3,8-phenanthroline were prepared and subsequently screened using electrochemical and spectroscopic techniques.It was determined that the stability of the radical film deposited on cathodic reduction of aqueous solutions of these salts may be strongly influenced by symmetry, steric, and electronic factors.From this basis, it was possible to design a viologen, 1,1'-bis-(2-methylbenzyl)-2-methyl-4,4'-bipyridinium dibromide (9), having electrochromic properties for electronic display applications superior to those already in existence.A radical film of mixed composition was found to be less susceptible to ageing effects than films generated from the individual dicationic salts.
- Barltrop, John A.,Jackson, Andrew C.
-
p. 367 - 372
(2007/10/02)
-
- Studies on Organometallic Compounds. III. Reaction of Trimethylstannylazines with Acyl Chlorides. A Novel C-C Bond Formation of Pyridine Nuclei
-
Introduction of an acyl group at the α-, β-, and γ-positions of pyridine nuclei was accomplished. 2-Trimethylstannyl-pyridine and -quinoline and 1-trimethylstannylisoquinoline directly reacted with various acyl chlorides to give the corresponding 2-pyridyl, 2-quinolyl, and 1-isoquinolyl ketones, respectively.Reaction of 3-trimethylstannylpyridine, -quinoline, and -isoquinoline with acyl chlorides proceeded smoothly under catalysis by PdCl2 or PdCl2(PPh3)2 to afford the corresponding ketones in good yields.Similary, 4-pyridyl, -quinolyl, and -isoquinolyl ketones were prepared from corresponding 4-trimethylstannyl derivatives and acyl chlorides.Keywords--trimethylstannylazine; palladium-catalyzed reaction; acylation; palladium dichloride; dichlorobis(triphenylphosphine)palladium(II)
- Yamamoto, Yutaka,Yanagi, Akihiko
-
p. 2003 - 2010
(2007/10/02)
-
- Process for substituting and dequaternizing pyridylethyl quaternary salts of pyridine and bypyridine bases
-
A process for dequaternizing a 2-(2-pyridyl)ethyl or 2-(4-pyridyl)ethyl quaternary salt of a pyridine or bipyridine base comprising the step of heating or reacting the pyridylethyl quaternary salt with a caustic material such as sodium hydroxide. Also included is a process for preparing a second pyridine base (or a bipyridine base) in which a first pyridine base is initially selected and its 2-(2-pyridyl)ethyl or 2-(4-pyridyl)ethyl quaternary salt or its acid salt prepared. An electrophilic, nucleophilic or coupling reaction can then be performed on the quaternary salt to change the substituent or to form the bipyridyl coupling and the resultant salt dequaternized with a caustic material, such as sodium hydroxide, to produce a second pyridine or a bipyridine base.
- -
-
-
