Monthly Archive for May, 2007

Luminescent compounds

Published
by
Dan Michael
on 18. May 2007
in chemistry
. 0 Comments

Colorful chemistry is great, but luminescent chemistry is even better. This week we synthesized two luminescent compounds: Alq3 with q = 8-quinolinolate and Eu(tta)3(phen) with tta=theonyltrifluoracetone, phen = 1,10-phenantroline.

Europium complex in solution

We tested the compounds under UV-light, where Alq3 emitted green light and Eu(tta)3(phen) red, due to fluorescence. The compounds would produce the same light in an electric field (electroluminescence), which is the basic principle behind OLED-displays, but unfortunately this requires a more complex setup.

Al kompleks pulver under UV-lysAlq3 emits green light when radiated with UV-light. This is a typical main group luminescent compound, where the luminescence comes from π-π*-transitions in the conjugated system (the other common transition is n-π*. As the transitions take place in molecular orbitals, there is a large gap between the many vibrational states and the emission peak is broad. Also, it’s only slightly shifted from the absorption peak.

Eu kompleks pulver under UV-lysEu(tta)3(phen) emits red light when radiated with UV-light. Eu is a rare-earth metal and the luminescence come from f-f-transitions on the metal. This gives very sharp emission-peaks (because the transitions take place in atomic orbitals), which is good. Also, the absorption peak is shifted a large difference from the absorption peak. This ensures the compound is really white when no stimuli is added, while Alq3 is slightly yellowish.

A fun fact is that an Europium (Eu) compound is used in the Euro banknotes for anti-counterfeiting.

Debt for carbon

Published
by
Dan Michael
on 2. May 2007
in rainforest
. 0 Comments

Maria is at a debt conference in Equador this week and tipped me about this very interesting case.

Ecuador is burdened with over 15 billion dollars of external debt. The Ecuadorian state-owned oil company Petroecuador have just discovered the largest untapped oil field in Equador (ITT), estimated to contain ~ one billion barrels of oil equivalent. With todays oil price, that is worth ~ 70 billion USD. Of course, there are also lots of costs linked with oil production (Petrobar estimates 5 billion USD), but still tapping the field would make a huge difference for the Equadorian economy!

Unluckily the oil field is located in the Equadorian rainforest, part of the Amazon-belt. But the Equadorian government have come up with an original solution: they will leave the oil field untapped if the international community offers to compensate the country with half of the forecasted lost revenues! President Correa estimates the compensation at around .35 billion USD per year.

“Ecuador doesn’t ask for charity,” said Correa, “but does ask that the international community share in the sacrifice and compensates us with at least half of what our country would receive, in recognition of the environmental benefits that would be generated by keeping this oil underground.”.

Read more at Environmental Newswire