2,21-p-Phenylene-bis-

Fig. 15. A branched [4]rotaxane from self-assembly of the triply-branched trisfbipyridini-um)derivative and bis-p-phenylene-34-crown-lO...

The macrocyclic polyether bis-p-phenylene-34-crown-10 (4) has a cavity large enough to accommodate [11] (Figure 6) simultaneously two acyclic guests 2 PF6, affording the [3]pseudorotaxane [(2)2-4][PF6]2. In this instance, however, the equi-... 

Over the last decade, noncovalent bonding interactions between appropriate Jt-elec-tron-deficient and Jt-electron-rich recognition sites have been exploited in our laboratories for the synthesis of catenanes and rotaxanes. 271 In the example illustrated in Figure 10, the bis(hexafluorophosphate) salt 11-2PF6 was treated 28 with trons-bis(pyridine)ethylene (12) in the presence of the previously formed macrocyclic polyether bis-p-phenylene-34-crown-10 (13). The resulting [2]catenane 14-4PF6 was isolated in 43 % yield after counterion exchange. 

Bis-p-phenylene-34-crown-10 synthesis—a receptor for n-electron-deficient aromatics... 

Figure 4.1 1 1 Adduct formed between paraquat and bis-p-phenylene-2>A-crown- (f...

Parallel studies involving the symmetrical crown, bis-p-phenylene-34-crown-lO, and the corresponding three tetracationic cyclophanes (Figure 5.6) derived from... 

Figure 5.6 Three tetracationic cyclophanes used to prepare catenaries with bis-p-phenylene-34-crown-lQ...

In contrast, when a larger tetracationic cyclophane ring was employed in another set of experiments, the formation of new [3]-catenanes was found to be more facile. ° The expanded ring was obtained by replacing the phenylene linker units in the normal tetracationic cyclophane with biphenylene units. This larger ring was found to form readily around two threaded crowns when the latter are present in the acetonitrile reaction mixture in several-fold excess. Both bis-p-phenylene-34-crown-lO and l,5-dinaphtho-38-crown-10 were successfully employed in separate reactions to produce the corresponding [3]-catenanes in 20 and 31% yields, respectively. 

Gibson et al. reported that the copolymerization of poly(THF) and a diol-pseudorotaxane consisting of 4,4/-bipyridinium salt and bis-p-phenylene crown ether with diisocyanate afforded the corresponding polyurethane with the interlocked structure [48] (Scheme 6). Although this polyurethane has a pseudopolyrotaxane structure, the interlocked structure is stable because the interaction between 4,4/-bipyridinium salt and bis-p-phenylene crown ether is strong enough to keep the inclusion complex. In this elastic polyurethane, the rotaxane unit acted as a hard segment. 

Since the inclusion complex between 4,4/-bipyridinium salt and bis-p-phenylene crown ether is stable, oligorotaxane can be prepared from oli-go(4,4 -bipyridinium salt) quantitatively. Stoddart et al. reported that olig-orotaxanes were prepared when oligo(4,4/-bipyridinium salt) bearing the pyridine groups at the termini were alkylated by bulky alkylation agent in the presence of bis-p-phenylene crown ether [49-51]. 

Figure 3.16 Electronic energy level diagram of Pt diynes and polyynes containing group 16 main group elements determined from absorption and PL data. Dashed lines represent the levels for the Pt diynes and polyyne containing bi(p-phenylene) spacer. The levels are arbitrarily shown to be of equal energy and aU energy values are quoted in eV...

Poly(urethane-rofaxa-bis(p-phenylene)- 34-crown-10 Segmented polyurethane host-guest complexation approach 80% threading efficiency. [240]... 

Synonyms 4,4 -diphenyl methane diisocyanate 4,4 -diisocyanodiphenylmethane MBI 4,4 -methylenediphenyl diisocyanate PMDI methylene bis(phenylisocyanate) diphenyl methane diisocyanate 4,4 -methylene bisphenyl isocyanate methylene diphenyl diisocyanate i,i -methylene bis(4-isocyanato)-benzene methylenebis(4-isocyanatobenzene) bis(p-isocyanatophenyl)methane i,i-methylenebis(4-isocyanatobenzene) bis(i,4-isocyanatophenyl)methane methylene bis(p-phenylene isocyanate) Caradate 30 Desmodur 44 4,4 diisocyanatodiphenylmethane Hylene M50 Isonate 125M Isonate 125MF methylene bis(p-phenyl isocyanate) methylene di-p-phenylene diisocyanate 4,4 -methylene diphenylene isocyanate Nocconate 300 methylene di-p-phenyl diisocyanate diphenylmethyl diisocyanate methylene bisphenyl isocyanate MDI... 

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