Phenyl spacer

The oligothiophenes 27 bear phenyl groups in the 3 -position of the thiophene cores that are para-substituted with electronically diverse functional groups (R = CF3, H, CH3, OCH3). Here, the phenyl spacers enhance the solubility of the oligomers and warrant the electronic communication between the elements of diver-... 

In one such TTF/DNP-based bistable [2]rotaxane 54+ (Fig. 8.6a), a long, rigid p-ter-phenyl spacer was employed between the TTF and DNP recognition sites and two tetraarylmethane stoppers were employed [22a] on both ends of the dumbbell component for the solution-phase switching studies. UV-Vis spectroscopy (Fig. 8.6b), which reveals the precise location of the CBPQT4+ ring on the dumbbell... 

Having established the ability of our molecule to replicate, we became interested in the generality of this shape for autocatalysis. To probe the spacing requirements for an effective template, we examined the effects of exchanging the naphthoyl spacer in ester (5) for a longer biphenyl and a shorter phenyl spacer [33]. While lengthening the spacer had beneficial effects (discussed in Section 1), almost no catalysis was observed with the shorter (23) (Table 1, entry 9) there are clearly certain steric requirements which have to be met for effective replication to occur. 

However, it is inadequate to believe that any mixture of bis-tridentate ligands with will produce triple-stranded helicates. We already mentioned in the introduction how some competing coimter-ions or solvent molecules may prevent the fixation of the third strand, thus leading to unsaturated complexes (Section 1.3, Figure 13B). A second illustrative example is shown in Figure 53, whereby the use of a 1-4-disubstituted phenyl spacer in L33 makes the output of the assembly process extremely sensitive to the stoichiometric k L33 ratio (Ronson et al., 2007). 

SAMs offer design flexibility both at the individual molecular and at the materials level ( surface engineering ), and represent model systems to explore specific interactions and reactions at surfaces and interfaces [106-108]. Assemblies of thiol-based organic molecules self-assembled on metal substrates are a special class of SAM s. These adsorbates are composed of one or two thiol-anchor groups, custom-designed alkyl or phenyl spacer imits and, in some cases, incorporated tailored functionalities [106,109-111]. The apphcation of SAMs covers diverse areas such as adhesion [112], lubri-... 

One can also obtain mutidimensional ECPs from actual multifunctional monomers, such as bispyr-rolylazobenzene or bis(2,5-dithenylpyrrolyl)azobenzene [100]. The electropolymerization of monomers with two heterocyclic moieties (pyrrole or bisthienylpyrrole) connected through conjugated phenyl spacers gives rise to cross-linked structures [86], since it was demonstrated that both heads took part to the polymerization process [85]. Another example of cross-linked ECP can be electrochemically obtained from a chiral dicarbazole monomer [292]. 

Figure 13.32. Porphyrin triads with MgP, ZnP, and H2P components. The linking position of the MgP has been systematically varied using a p-phenyl spacer at the meso position in 39, and at a beta position in 40. In 41 and 42, m-phenyl spacers are attached at meso and beta carbons, respectively.

In both the Ru-Ru complexes, [(ttpy)Ru(tpy-ph -tpy)Ru(ttpy)] +, and the Ru-Os mixed-metal complexes, [(ttpy)Ru(tpy-ph,-tpy)Os(ttpy)] +, the lowest energy spin allowed electronic transition is an M(d7i) -> BL(ti ) CT transition, where BL = bridging ligand (Table 4). When two phenyl spacers are used, the M(d7t) tpy-ph,-tpy(7t ) CT transition is only slightly lower in energy than the M - t y for the model monometallic, [M(ttpy)2] . As the number of phenyl spacer is decreased, the M(dti) y-ph,- y(ii ) CT transition shifts to lower... 

To further investigate the ability of the phenyl spacers to electronically couple two metal centers, Sauvage et al. studied a system where an insulating, saturated hydrocarbon was used as part of the spacer between the tpy ends of the tpy-ph -tpy bridging ligand. Bicylco[2.2,2]octane (bco) was used between two phe-... 

Initially, heteroatomic anchoring groups were introduced for non-porphyrin dyes [14]. Only afterwards, these groups were introduced for porphyrins. A series of ZnPs with different numbers of anchoring groups at me o-positions [47] and one with the phenyl spacer in the A group [48] were synthesized and applied to DSSC (Scheme 26). 

Two-photcMi absorptimi and ultiafast dynamics of spin photoexcitations have been used for the characterizatimi of cmijugated polymers containing platinum atoms (Scheme 10.8). These complexes show a record intersystem crossing time of 1 ps (with one phenyl spacer) and 6 ps (with three phenyl spacers). This tunable ultrafast intersystem crossing determines the intensity ratio of the phosphorescence and fluorescence emissimi bands and is potentially useful for apphcatimis for white OLEDs [32]. 

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