Acta Phys. -Chim. Sin. ›› 2018, Vol. 34 ›› Issue (7): 776-780.doi: 10.3866/PKU.WHXB201711091

Special Issue: Toward_Atomically_Precise_Nanoclusters_and_Nanoparticles

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[Ag25(SC6H4Pri)18(dppp)6](CF3SO3)7·CH3CN (HSC6H4Pri = 4-t-isopropylthiophenol, and dppp = 1, 3-bis(diphenyphosphino)propane) Cluster Containing a Sandwich-like Skeleton: Structural Characterization and Optical Properties

An XIE1,Zhi WANG2,Qiaoyu WU3,Liping CHENG2,3,Genggeng LUO3,*(),Di SUN2,*()   

  1. 1 Key Laboratory of Functional Materials and Applications of Fujian Province, School of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024, Fujian Province, P. R. China
    2 Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R. China
    3 College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, Fujian Province, P. R. China
  • Received:2017-10-18 Published:2018-03-26
  • Contact: Genggeng LUO,Di SUN E-mail:ggluo@hqu.edu.cn;dsun@sdu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21641011);the National Natural Science Foundation of China(21571115);the National Natural Science Foundation of China(21701133);the Natural Science Foundation of Fujian Province, China(2015J01053);the Fujian Key Laboratory of Functional Materials and Applications(fma2017107)

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Abstract:

Crystalline silver cluster compounds are highly interesting owing to their intriguing structure and potential technological application in luminescence, semiconductivity, and as precursors for nonlinear optical materials. Typically, the synthesis of silver clusters involves the use of protecting ligands such as thiolates, phosphines, and alkynes, which have been found to be critical for cluster size and shape tuning. Among these nanoclusters, pentacosanuclear silver clusters (Ag25) have only been reported with either thiolate ligands or phosphine ligands, while those bearing mixed protecting ligands are rather rare. In the course of our exploration of novel silver clusters, a new silver thiolate precursor (iPrC6H4SAg)n was used to construct nanosized silver clusters. In the presence of 1, 3-bis(diphenyphosphino)propane (dppp) and CF3SO3Ag, the pentacosanuclear silver cluster [Ag25(SC6H4Pri)18(dppp)6](CF3SO3)7·CH3CN (designated as Ag25, HSC6H4Pri = 4-t-isopropylthiophenol) ligated both by thiolate and phosphine ligands was obtained under ultrasonic reaction conditions. Yellow block crystals were isolated from the solution, whose molecular structure was elucidated by single-crystal X-ray analysis. The skeleton of the Ag25 cluster comprises a sandwich-like motif containing two structurally very similar cylinders sharing a metal-cluster plane. The core of each cylinder presents the overall shape of a twisted hexagonal cylinder made of two connected Ag3S3 units, with six sulfur atoms and six silver atoms alternating on a puckered drum-like surface. The metal-cluster plane contains one type of pure-Ag tetragons showing significant Ag…Ag argentophilic interactions. The optical properties of Ag25 were investigated in the solid state. A band gap of ~2.5 eV was estimated for Ag25 from the optical absorption spectrum, suggesting this cluster to be a potential wide-gap semiconductor. This Ag25 cluster was also found to emit green luminescence at λ = 505 nm and room temperature.

Key words: Silver cluster, Crystal structure, Optical property, Luminescence, Argentophilicity