No abstract

No abstract

The selectivity of 5‘-TGGGT-3‘ and 5‘-CGGGC-3‘ sequences toward photoinduced one-electron oxidation was examined experimentally and by ab initio molecular orbital (MO) calculations. It was confirmed experimentally that G2 of 5‘-TG1G2G3T-3‘ is more reactive than G1, while for 5‘-CG1G2G3C-3‘ the selectivity is reversed, that is, G1 > G2. The ab initio MO analyses were performed to elucidate the difference of the selectivities between 5‘-TGGGT-3‘ and 5‘-CGGGC-3‘ sequences. For the 5‘-TGGG-3‘ sequence, the spin densities of G1 • and G2 • in neutral radical (5‘-TG1G2G3-3‘)• have a similar pattern, and the shapes of the corresponding radical orbitals are also very similar. It was concluded that the selectivity is due to the stability of the (5‘-TG1G2G3-3‘)• neutral radicals; that is, 5‘-TG1G2 •G3-3‘ is more stable in energy than 5‘-TG1 •G2G3-3‘. For the 5‘-CGGG-3‘ sequence, it was found that the spin density on N1 of G1 • in neutral radical (5‘-CG1G2G3-3‘)• is distinguishably different from the corresponding spin density of G2 •, which has a pattern similar to those of G1 • and G2 • in 5‘-TG1G2G3-3‘. The radical orbital (SOMO) of G1 • is delocalized on guanine base and up to the paired cytosine base, while the radical orbital of G2 • is essentially localized on guanine base. This drastic difference of the electron population in the radical orbitals, caused by the stacking interaction with the 5‘-side G of the opposite strand, can explain why G1 is more reactive than G2 in the 5‘-CG1G2G3-3‘ sequence.

We synthesized a new porous coordination polymer Cu[Cu(pdt)2], which shows relatively high electrical conductivity (6 x 10(-4) S cm(-1) at 300 K) by the introduction of electron donors and acceptors as building units. This compound is applicable as a porous electrode with high power density. In addition, this compound forms a triangular spin lattice and shows spin frustration.