第四种晶相最密排列方式

The fourth crystallographic closest packing

迄今为止,在晶体中共发现了三种最密排列方式。金属纳米团簇研究的兴起,为发现新的晶相排列提供了契机,这是因为金属纳米团簇粒子具有亚纳米尺寸和组成结构的多样性。近年来,我们在研究金属纳米团簇内部结构的基础上,开展了金属纳米团簇的外部结构(晶相排列)研究,继在Au_(92)团簇中发现4H最密排列后,最近合成了一个新的团簇Au_(60),并在它的晶体结构中发现了一种独特的晶相最密排列方式6HLH,这是继1979年第三种晶相最密排列方式发现后的一种新的最密排列方式。6HLH排列导致Au_(60)固态荧光的显著衰减。另外,我们在这种团簇的结构中发现了6个四面体配位的μ4-S和一对巨型Au20S3(SCH2Ph)18长钉。我们的工作不仅对金属纳米团簇研究,而且对晶相排列的研究具有重要的启发意义。

Three crystallographic closest packings have been reported so far. The emerging of metal nano- clusters research provides opportunities for the finding of novel crystallographic arrangement since metal nanoclusters are sub-nano-sized in diverse compositions and structures. Basing on the research on internal structure of metal nanocluster, we recently conducted the research on external structure （crystallographic arrangement） of metal nanocluster. Following the revealing of 4H arrangement in the crystals of Augz nanoclusters, very recently we synthesized a novel nanocluser-Au60 and found a unique closest packing- 6HLH, which is novel since the finding of the third closest packing in 1979. The 6HLH arrangement re- sults in the obvious loss of solid photoluminescence of amorphous Au60. Other interesting findings include that there are six tetrahedral-coordinate μ4-S atoms and a pair of Au20S3（SCH2Ph）ls giant staple motifs in the atomic structure of Au60. Our work has important implications to not only nanoclusters but also crys- tallographic arrangement research.