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Bare Clusters Derived from Protein Templates: Au 25 + , Au 38 + and Au 102 +
Author(s) -
Baksi Ananya,
Pradeep Thalappil,
Yoon Bokwon,
Yannouleas Constantine,
Landman Uzi
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201200927
Subject(s) - gold cluster , chemistry , crystallography , cluster (spacecraft) , binding energy , colloidal gold , delocalized electron , electronic structure , chemical physics , covalent bond , atom (system on chip) , nanoparticle , atomic physics , nanotechnology , materials science , computational chemistry , physics , organic chemistry , computer science , embedded system , programming language
A discrete sequence of bare gold clusters of well‐defined nuclearity, namely Au 25 + , Au 38 + and Au 102 + , formed in a process that starts from gold‐bound adducts of the protein lysozyme, were detected in the gas phase. It is proposed that subsequent to laser desorption ionization, gold clusters form in the gas phase, with the protein serving as a confining growth environment that provides an effective reservoir for dissipation of the cluster aggregation and stabilization energy. First‐principles calculations reveal that the growing gold clusters can be electronically stabilized in the protein environment, achieving electronic closed‐shell structures as a result of bonding interactions with the protein. Calculations for a cluster with 38 gold atoms reveal that gold interaction with the protein results in breaking of the disulfide bonds of the cystine units, and that the binding of the cysteine residues to the cluster depletes the number of delocalized electrons in the cluster, resulting in opening of a super‐atom electronic gap. This shell‐closure stabilization mechanism confers enhanced stability to the gold clusters. Once formed as stable magic number aggregates in the protein growth medium, the gold clusters become detached from the protein template and are observed as bare Au n + ( n =25, 38, and 102) clusters.