The new ligand 2,9-bis[(6-methyl-2,2@-bipyridin-6@-yl)methyleneoxymethylen-yl]-1,10-phenanthroline (1) was prepared and was shown to self-assemble into double-stranded helicates upon reaction with Cu`, Ag`and Zn2`, thus a †ording the Ðrst trinuclear double-stranded zinc helicate. The [M \ Cu`(n \ 1), Ag`(n \ 1) or [(1) 2M 3 ]3nZ n2`(n \ 2)] helicates were characterized by 1D, 2D and di †usion NMR. FAB mass spectrometry corroborated the structure of the silver and the copper helicates and was characterized by X-ray crystallography. [(1) 2Cu 3 ]3T he detailed assignments of the 1H NMR spectra of these helicates have shown that H-10 absorbs at a much higher Ðeld when compared to the other protons of these complexes. This high-Ðeld shift is a unique characteristic of the helicates of 1 and is not found in structurally related helicates. The NMR spectra of these helicates, at room temperature, are consistent with an average solution structure having a symmetry. Variable-temperature D 2 1H NMR (VT-NMR) reveals that the silver helicate of 1 is much more labile than its copper helicate. From the VT-NMR spectra it seems that two, nearly separate, stages are observed in the dissociation process of [(1) 2Ag 3 ]3`. The activation energy of the Ðrst process for in was found to be 16.6 ^0.2 kcal mol~1. As [(1) 2Ag 3 ]3`DMSO-d 6 expected, the energy barriers for the respective copper helicate are even higher. The crystal structure of [(1) 2Cu 3 ]3s hows that the total length and the pitch length are B17 and 12 respectively.Ó,

The ligands 2,9-bis[(6-methyl-2, 2'-bipyridin-6'-yl)methyleneoxymethylenyl]-1,10-phenanthroline (6), 6' ',6' "-bis[(6-methyl-2, 2'-bipyridin-6'-yl)methyleneoxymethylenyl)]-2' ',2' "-bipyridine (2), 5,5'-bis[(6-methyl-2,2'-bipyridin-6'yl)methyleneoxymethylenyl]-2, 2'-bithiophene (7), and 6,6'-bis[(6-methyl-2, 2'-bipyridin-6'-yl)methyleneoxymethylenyl]-2,2'-biphenyl (8) and their respective homo- and heteroleptic double-stranded copper(I) complexes were prepared and characterized in order to estimate the importance of self-recognition in the self-assembly processes of double-stranded copper complexes. The homoleptic double-stranded copper complexes of 2, 6, 7, and 8 were characterized by NMR, FAB-MS, and electrochemistry. It was found that 6 and 2 each form a single double-stranded helicate having the structure of [(L)(2)Cu(3)](3+) (L = 2 or 6), 7 forms two double-stranded [(7)(2)Cu(3)](3+) complexes, and 8 results in a mixture of at least two [(8)(2)Cu(2)](2+) complexes. The potential shift, DeltaE degrees (,) of the Cu(+)/Cu(2+) redox process of these complexes reflects the binding affinity of the different binding sites to the copper cation. The electrochemical data show that the central units have a higher affinity to Cu(+) as compared to the off-center binding sites. NMR was used to determine the actual complex composition obtained from different mixtures of 2, 6, or 7 with Cu(+). Interestingly, we have found that, although 6, 2, and 7 each form homoleptic double-stranded complexes, no heteroleptic double-stranded copper complexes were formed from the mixtures of 7 with either 6 or 2. However, when mixtures of 6 and 2 are used, helicate distributions seem to follow simple statistics. These results are discussed in terms of the relative importance of self-recognition in the self-assembly of double-stranded helicates.

The calculations of polarization diagrams of photoluminescence for pair centres in azincblende lattice, e.g. donor-acceptorpairs, are presented. Theclassical dipoleapproximation is applied for three types of pair spectra. The extreme values of the polarization diagram are expressed via coordinates of the corresponding pair centre in a lattice. I1 is possible to identify the different typesof pair spectra and to provide enumeration ofthe pairs from their polarization characteristics. The calculations represent a theoretical basis for the new method of selectively excited polarized luminescence of pair lines.

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