Dedicated to Professor David N. Reinhoudt on the occasion of his 60th birthdayIn continuation of a previous study on the modulation of p-electron conjugation of oligo(triacetylene)s by insertion of central hetero-spacer fragments between two (E)-hex-3-ene-1,5-diyne ((E)-1,2-diethynylethene, DEE) moieties (Fig. 1), a new series of trimeric hybrid oligomers (14 ± 18 and 22 ± 24, Fig. 2) were prepared (Schemes 1 ± 3). Spacers used were both electron-deficient (quinoxaline-based heterocycles, pyridazine) and electron-rich (2,2'-bithiophene, 9,9-dioctyl-9H-fluorene) chromophores. With 19 ± 21 (Scheme 4), a series of transition metal complexes was synthesized as potential precursors for nanoscale scaffolding based on both covalent acetylenic coupling and supramolecular assembly. The UV/VIS spectra ( Fig. 3) revealed that the majority of spacers provided heterotrimers featuring extended p-electron delocalization. The new hybrid chromophores show a dramatically enhanced fluorescence compared with the DEE dimer 13 and homo-trimer 12 (Fig. 5). This increase in emission intensity appears as a general feature of these systems: even if the spacer molecule is non-fluorescent, the corresponding hetero-trimer may show a strong emission ( Table 2). The redox properties of the new hybrid chromophores were determined by cyclic voltammetry (CV) and rotating-disk voltammetry (RDV) ( Table 3 and Fig. 5). In each case, the first one-electron reduction step in the hetero-trimers appeared anodically shifted compared with DEE dimer 13 and homo-trimer 12. With larger spacer chromophore extending into two dimensions (as in 14 ± 18, Fig. 2), the anodic shift (by 240 ± 490 mV, Table 3) seems to originate from inductive effects of the two strongly electron-accepting DEE substituents rather than from extended p-electron conjugation along the oligomeric backbone, as had previously been observed for DEE-substituted porphyrins.Introduction. ± In a previous study, we had explored how the properties of oligomers made from (E)-1,2-diethynylethene (DEE, (E)-hex-3-ene-1,5-diyne) repeating units can be tuned or changed by the insertion of spacer chromophores [1]. For this purpose, a series of eleven hybrid oligomers 1 ± 11 (Fig. 1) were prepared, in which mostly aromatic hetero-spacers with different electronic characteristics were introduced between two DEE moieties. UV/VIS Studies revealed that the majority of the hetero-spacers were less effective than the homo-spacer DEE in trimeric 12 in facilitating p-electron delocalization along the linear conjugated oligomeric backbone. Electrochemical investigations by cyclic voltammetry (CV) and rotating-disk voltammetry (RDV) confirmed these results.On the other hand, fluorescence studies clearly demonstrated that a desirable function can be created or strongly enhanced upon insertion of hetero-spacers into pure DEE oligomers [2 ± 4]. Thus, the heterocyclic derivatives 7 ± 9, containing pyridine, pyrazine, or thiophene spacers, respectively, feature a strong fluorescence emission, which is present to a signi...