A series of p,p‘-disubstituted 7-phenyl-7-(2-fluorophenyl)norbornanes 5xy has been prepared, and the barrier (ΔG #) to 160° libration around the 2-fluoroaryl-norbornane bond has been measured by DNMR. There is spectroscopic evidence of strong homoconjugative and charge-transfer (CT) interactions between both aryl groups of 5xy. However, the relationship between ΔG # and the nature of the substituents X and Y is accounted for only by electrostatic interactions between both aryl groups in the ground state as well as in the transition state of the libration. Therefore, the notion of CT and aromatic homoconjugation as strong attractive forces between aryl groups should be definitively rejected.

A methodology for the synthesis of monodisperse homoconjugated oligomers (dimer, trimer, and tetramer) derived from cofacial 7,7-diphenylnorbornane (DPN) is described. Extended aromatic homoconjugation is observed in these oligomers as revealed by the electronic spectra. The effective homoconjugation length (EHL) is in the range of 4-5 DPN subunits.

The use of a thiol-functionalized nonionic surfactant to stabilize spherical gold nanoparticles in water induces the spontaneous formation of polyrotaxanes at the nanoparticle surface in the presence of the macrocycle α-cyclodextrin. Whereas using an excess of surfactant an amorphous gold nanocomposite is obtained, under controlled drying conditions the self-assembly between the surface supramolecules provides large and homogenous supercrystals with hexagonal close packing of nanoparticles. Once formed, the self-assembled supercrystals can be fully redispersed in water. The reversibility of the crystallization process may offer an excellent reusable material to prepare gold nanoparticle inks and optical sensors with the potential to be recovered after use.

composition of donor : acceptor = 1 : 0.4, its upper bands are not half-filled. Whereas all other k-type superconductors have the composition of donor : acceptor = 2 : 1 and therefore, half-filled upper bands. The deviation from halffilling makes the on-site Coulomb repulsion comparatively unimportant; this stabilizes the metal state, but is disadvantageous with respect to superconductivity. [15] The same situation has been found in (EOET±TTP) 3 AsF 6 , [5b] and (CH± TTP)(I 3 ) 0.31 . [5c] In summary, we have found a k-type organic metal based on a newly prepared TTP derivative CPEO±TTP. To our knowledge, there is no report on metallic k-type salt base on ethylenedioxy-substituted TTF. [16] In contrast, CPEO± and EOET±TTP afford k-type salts retaining metallic conductivity down to low temperature. Therefore, combination of TTP framework and ethylenedioxy substituent would be suitable for exploring new k-type metals. The preparation of radical-cation salts based on the other ethylenedioxy substituted TTPs is actively in progress. Experimental CPEO±TTP: Red microcrystals; m.p. = 246±247 C (decompose.); 1 H NMR (270 MHz, CS 2 -[ 2 H 6 ]benzene) d 4.17 (s, 4H), 2.49±2.56 (m, 4H), 2.35± 2.45 (m, 2H); I.R. (KBr) u (cm ±1 ) 1653, 1452, 1168. (CPEO±TTP)(SbF 6 ) 0.4 : C 15 F 2.4 H 10 O 2 S 8 Sb 0.4 , M = 573.02, monoclinic, space group C2/c, a = 45.144(3), b = 7.984(4), c = 10.999(5) . b = 99.72 (2), V = 3907(2) 3 , Z = 8, D c = 2.235 g/cm 3 , Mo Ka radiation, l = 0.71069 , m = 23.06 cm ±1 , F(000) = 2576.00. The data were collected on a Rigaku AFC7R diffractometer equipped with graphite monochromated Mo Ka radiation using the o±2y scan technique to a maximum 2y of 55. The structure was solved by direct methods and refined by full-matrix least squares analysis (anisotropic for non-hydrogen atoms) to R = 0.065, R w = 0.070 for 1359 observed (I ³ 3s (I)) reflections from 4816 unique data. All calculations were performed using the teXsan crystallographic software package of Molecular Structure Corporation. Atomic coordinates, bond distances and angles, and thermal parameters have been deposited at the Cambridge Crystallographic Data Center.

A new donor-bridge-acceptor (D-B-A) dyad consisting of ruthenium(II) and iridium(III) species separated by an homoconjugated bridge derived from 7,7-diphenylnorbornane [Ir-Nor-Ru](3+) has been synthesised. The photophysical and electrochemical properties of the heterodinuclear complex have been compared with those of the analogous homodinuclear complexes [Ru-Nor-Ru](4+) and [Ir-Nor- Ir](2+) . Transient absorption spectra on the nanosecond and sub-picosecond timescales show, for the first time, that an homoconjugated bridge can mediate efficiently in the photoinduced energy transfer from the iridium(III) to the ruthenium(II) centres according to a Dexter-type mechanism.