This week, I returned from the his­toric 50^th Sani­bel Sym­po­sium. Over 350 chemists and physi­cists gath­ered together to cel­e­brate half-centennial suc­cess of quan­tum and com­pu­ta­tional chem­istry. One lec­ture that caught my atten­tion was a ple­nary talk “Con­duct­ing Poly­mers: a saga of more than 50 years” by pro­fes­sor Jean-Marie Andre. Pro­fes­sor Andre empha­sized a role of the­ory in describ­ing the phe­nom­ena of poly­mer con­duc­tiv­ity. The role, unfor­tu­nately, was never prop­erly acknowl­edged… In fact, con­duct­ing poly­mers were prac­ti­cally pre­dicted in 1962 by John Pople and S.H. Walm­s­ley [1] a long before their exper­i­men­tal discovery.

In this clas­si­cal paper Pople and Walm­s­ley intro­duced con­cept of soli­tons in poly­acety­lene. The neu­tral soli­ton is a rad­i­cal mis­fit which exists in the mid­dle of a long poly­ene chain con­tain­ing an odd num­ber of con­ju­gated car­bons and which con­sists of sev­eral suc­ces­sive bonds of sim­i­lar lengths near which the unpaired elec­tron is local­ized. Authors sug­gested that such a defect could be mobile and, if charged, could be respon­si­ble of an high elec­tri­cal con­duc­tiv­ity. →

6th March, 2010 3153 Commentshttp://www.isayev.info/from-conducting-polimers-to-first-organic-superconductors/From+Conducting+Polimers+to+First+Organic+Superconductors2010-03-06+22%3A33%3A38Olexandr+Isayev

PhD Comics, didn’t include DOIs in their recent bib­li­og­ra­phy of Christmas-related cita­tions. For lazy peo­ple, com­piled list is below:

• Christ­mas Dis­ease. Biggs, R, Dou­glas, A, Mac­far­lane, R, Dacie, J, Pit­ney, W, Merskey, C & O’Brien, J, 1952, BMJ, vol. 2, no. 4799, pp. 1378 – 1382.
  DOI: http://dx.doi.org/10.1136/bmj.2.4799.1378

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29th December, 2009 Comments Off

The Brookhaven team, has been refin­ing tech­niques to use strands of arti­fi­cial DNA as a highly spe­cific kind of Vel­cro or glue to link up nanopar­ti­cles. Such DNA-based self-assembly holds promise for the ratio­nal design of a range of new mate­ri­als for appli­ca­tions in mol­e­c­u­lar sep­a­ra­tion, elec­tron­ics, energy con­ver­sion, and other fields. But none of these struc­tures has had the abil­ity to change in a pro­gram­ma­ble man­ner in response to mol­e­c­u­lar stim­uli — until now. “Now we’re using a spe­cial type of DNA-linking device — a kind of ‘smart glue’ — that affects how the par­ti­cles con­nect to make struc­tures that are switch­able between dif­fer­ent con­fig­u­ra­tions,” says Oleg Gang a team lead. This reli­able, reversible switch­ing could be used to reg­u­late func­tional prop­er­ties — for exam­ple, a material’s flu­o­res­cence and energy trans­fer prop­er­ties — to make new mate­ri­als that are respon­sive to chang­ing con­di­tions, or to alter their func­tions on demand.

a) Ide­al­ized schematic illus­trat­ing the struc­ture of the device (l_d) link­age, with A’, D’ and B’ recog­ni­tion sequences. b) A bcc unit cell rep­re­sen­ta­tion of a bulk three-dimensional super­lat­tice con­sist­ing of nanopar­ti­cles A – p and B – p inter­con­nected by l_d. © Nature Pub­lish­ing Group.

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22nd December, 2009 Comments Off