Oligomers ladder

Phenylenediamines, alkylation, 2 197 p-Phenylene diisocyanate (PPDI), 25 462 p-Phenylene ladder oligomers, sulfonio-bridged, 23 709, 716... 

Scheme 18. Synthesis of rigid ladder oligomers with [2.2]paracyclophane units by repetitive Diels-Alder reactions [43]...

Formal 1 1 copolymers incorporating PTL ladder repeat units can be prepared in excellent yield by interfacial polymerization of ladder oligomer bis-acylhalides with neopentyldiamine. The resulting polymers are soluble, processible and are thermally stable to ca. 400 C. These new polymers exhibit values exceeding 10" esu at 532 nm, and the response of these materials at other wave lengths and the mechanism of DFWM decay is currently under investigations. 

Kintzel O, Luger P, Weber M, Schliiter AD (1998) Ring-chain equilibrium between an [18] cyclacene derivative and a ladder oligomer. Eur J Org Chem 1998(1) 99-105... 

The syntheses of the first sulfonio-bridged, p-phenylene ladder oligomers (44) that have a planar ribbon-type structure have also been reported (60). 

Fig. 4.7 Five different types of PNA-dsDNA complexes. DNA is shown schematically as a ladder, and the PNA oligomers are shown in bold...

As described for the corresponding polymers, a powerful strategy for arriving at soluble oligomers with maximum conjugative interaction is incorporation of the PPP backbone into a stepladder - or ladder (see Sect. 2.2.) - framework, in... 

Template copolymerization seems to be applied to the synthesis of copolymers with unconventional sequences of units. As it was shown, by copolymerization of styrene with oligomers prepared from p-cresyl-formaldehyde resin esterified by methacrylic or acrylic acid - short ladder-type blocks can be introduced to the macromolecule. After hydrolysis, copolymer with blocks of acrylic or methacrylic acid groups can be obtained. Number of groups in the block corresponds to the number of units in oligomeric multimonomer. Such copolymers cannot be obtained by the conventional copolymerization. 

A variety of oligomers with novel drum and ladder structures have also been prepared. They have the formulas [R Sn(0)02CR]6 and [(R Sn(0)02CR)2 R Sn(02CR)3 2, and contain four- and six-membered rings. They can be synthesized by the reaction of stannoic acid with a carboxylic acid, but the reaction of RSnCl3 with the silver salt of a carboxylic acid can also be used. If diphenylphosphinic acid or dicyclohexylphosphinic acid is used instead of the carboxylic acid, oxygen-capped clusters or cubic and butterfly structures are obtained.69... 

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