Time-Dependent Density Functional Molecular Orbital and Excited State Calculations on Bis(porphyrinyl)butadiynes in the Monocationic, Neutral, Monoanionic, and Dianionic Oxidation States

We report a theoretical study of the multiple oxidation states (1+, 0, 1−, and 2−) of a meso,meso-linked diporphyrin, namely bis[10,15,20-triphenylporphyrinatozinc(II)-5-yl]butadiyne (4), using Time-Dependent Density Functional Theory (TDDFT). The origin of electronic transitions of singlet excited states is discussed in comparison to experimental spectra for the corresponding oxidation states of the close analogue bis{10,15,20-tris[3‘,5‘-di-tert-butylphenyl]porphyrinatozinc(II)-5-yl}butadiyne (3). The latter were measured in previous work under in situ spectroelectrochemical conditions. Excitation energies and orbital compositions of the excited states were obtained for these large delocalized aromatic radicals, which are unique examples of organic mixed-valence systems. The radical cations and anions of butadiyne-bridged diporphyrins such as 3 display characteristic electronic absorption bands in the near-IR region, which have been successfully predicted with use of these computational methods. The radicals are clearly of the “fully delocalized” or Class III type. The key spectral features of the neutral and dianionic states were also reproduced, although due to the large size of these molecules, quantitative agreement of energies with observations is not as good in the blue end of the visible region. The TDDFT calculations are largely in accord with a previous empirical model for the spectra, which was based simplistically on one-electron transitions among the eight key frontier orbitals of the C4 (1,4-butadiyne) linked diporphyrins.

Security of Two-Party Identity-Based Key Agreement

Identity-based cryptography has become extremely fashionable in the last few years. As a consequence many proposals for identity-based key establishment have emerged, the majority in the two party case. We survey the currently proposed protocols of this type, examining their security and efficiency. Problems with some published protocols are noted.

Party 25

Party 25 involved the conception and public launch of a radically new form of political party during that year’s Australian general election. The entire project was also intentioned as a conceptual artwork. Party 25 avoided conventional party-political approaches and was neither a protest group nor an advocacy organisation, but rather a new form of political association that confronted what we understood as the debilitating limits and impotence of contemporary parliamentary democracies in transitioning our societies towards ecological sustainability.----- Party 25 was based on responding to one fundamental question which all of its policies served - “how does humanity get to the 25th century?” By basing itself on a dramatically long-term approach uncommon within conventional politics it raised the proposition that humanity does not have an assured future. Party25 therefore shaped its agendas around the idea that any future now lies in human hands and so how humanity treats the ecologies on which it depends innately determines the quality of the inseparable relationship between its being, and the being of the biophysical world.----- The project was conceived through a number of discussion papers, workshops and creative works and was launched publicly at the Judith Wright Centre Brisbane accompanied by a full length showing of evocative imagery, text and sound, a series of speeches and the launch of a succinct web presence. Through the website and this party launch a community of interested participants and creative practitioners was sought who then would form the basis of a nascent community of change.