Clarifying the Electronic Structure of Anion-Templated Silver Nanoclusters by Optical Absorption Spectroscopy and Theoretical Calculation
Yusuke Horita, Sakiat Hossain, Mai Ishimi, Pei Zhao, Miyu Sera, Tokuhisa Kawawaki, Shinjiro Takano, Yoshiki Niihori, Toshikazu Nakamura, Tatsuya Tsukuda, Masahiro Ehara, Yuichi Negishi
Abstract
High Resolution Image Download MS PowerPoint Slide Electronic structures of anion-templated silver nanoclusters (Ag NCs) are not well understood compared to conventional, template-free Ag NCs. In this study, we synthesized three new anion-templated Ag NCs, namely [S@Ag 17 (S-4CBM) 15 (PPh 3 ) 5 ] 0, [S@Ag 18 (S-4CBM) 16 (PPh 3 ) 8 ] 0, and [Cl@Ag 18 (S-4CBM) 16 (PPh 3 ) 8 ][PPh 4 ], where S-4CBM = 4-chlorobenzene methanethiolate, and single-crystal X-ray crystallography revealed that they have S@Ag 6, S@Ag 10, and Cl@Ag 10 cores, respectively. Investigation of their electronic structures by optical spectroscopy and theoretical calculations elucidated the following unique features: (1) their electronic structures are different from those of template-free Ag NCs described by the superatomic concept; (2) optical absorption in the range of 550–400 nm for S 2– -templated Ag NCs is attributed to the charge transitions from S 2– -templated Ag-cage orbitals to the s-shaped orbital in the S 2– moiety; (3) the Cl – -templated Ag NCs can be viewed as [Cl@Ag 18 (S-4CBM) 16 (PPh 3 ) 8 ] 0 [PPh 4 ] 0 rather than the ion pair [Cl@Ag 18 (S-4CBM) 16 (PPh 3 ) 8 ] − [PPh 4 ] +; and (4) singlet-coupled singly occupied orbitals are involved in the optical absorption of the Cl – -templated Ag NC.