РОССИЙСКАЯ АКАДЕМИЯ НАУК

УРАЛЬСКОЕ ОТДЕЛЕНИЕ

ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА
   
| | | | |
| | | |
 27.01.2010   Карта сайта     Language По-русски По-английски
Новые материалы
Экология
Электротехника и обработка материалов
Медицина
Статистика публикаци


27.01.2010


Boron cluster forms unique ring system



24 January 2010



Clusters of nineteen boron atoms gather together in a ring structure unlike any other seen, with two planar Pi-bonded aromatic systems nestled inside one another.   


Lai-Sheng Wang at Brown University and Alexander Boldyrev at Utah State University in the US made the discovery: 'I was really excited when my postdoc, Wei Huang, first showed it to me,' Wang told Chemistry World. 'It's so beautiful, so circular.' 


The US chemists found that the lowest energy form of B19- boasts a pentagonal six-atom group sharing two Pi-electrons, surrounded by thirteen boron atoms sharing ten electrons. Although concentric Pi-systems have been seen in organic molecules, none have exactly this electronic configuration.   












B19- features a central 6-atom pentagon that shares two pi-electrons, surrounded by thirteen boron atoms that share 10 pi-electrons



© Nature Chemistry



Xiao Cheng Zeng, an expert in modelling molecular clusters at the University of Nebraska-Lincoln, US, points out that this is actually 'the first time a concentric doubly ?-aromatic system is shown to exist in a non-carbon based structure'. He calls the work 'a significant advance in aromatic chemistry'.


Replacing the central B6 unit with transition metals might produce boron-based nanosystems with tunable optical, electronic and magnetic properties, Wang and Boldyrev suggest. However Wang admits that they currently don't even know whether  the B19- ring's structure is stable. 'It's like the buckyball, which was first discovered in the gas phase,' Wang pointed out. 'It wasn't until it was synthesised in the bulk form that it was realised it was stable.' 


Wang's group had actually generated the B19 cluster  years before, using a laser to vaporise a 10B-enriched disc target. They then measured the cluster's photoelectron spectrum to produce an 'electronic fingerprint'. From then on, the puzzle was which structure generated the correct spectrum.  


The breakthrough came when Huang used a so-called Basin-Hoping algorithm to search for the most stable atomic arrangement of the 19-atom cluster. Then Boldyrev's group performed more accurate calculations to generate a theoretical spectrum confirming the proposed concentric ring structure, and analysed its chemical bonding to discover the double Pi-system.  


The teams are now continuing on to ever larger boron clusters, to determine when they become three-dimensional.  


Andy Extance



Дизайн и программирование N-Studio 
А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

  • © 2004-2019 ИХТТ УрО РАН
    беременность, мода, красота, здоровье, диеты, женский журнал, здоровье детей, здоровье ребенка, красота и здоровье, жизнь и здоровье, секреты красоты, воспитание ребенка рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок медицина, клиники и больницы, болезни, врач, лечение, доктор, наркология, спид, вич, алкоголизм православные знакомства, православный сайт творчeства, православные рассказы, плохие мысли, православные психологи рождение ребенка,пол ребенка,воспитание ребенка,ребенок дошкольного возраста, дети дошкольного возраста,грудной ребенок,обучение ребенка,родить ребенка,загадки для детей,здоровье ребенка,зачатие ребенка,второй ребенок,определение пола ребенка,будущий ребенок